The new Pembury Hospital, Kent, provides an example of

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The new Pembury Hospital, Kent, provides an example of Powered By Docstoc
					             The new Pembury Hospital, Kent, provides an example of the benefits to be gained from
             using post-tensioned suspended concrete floors. These benefits are being increasingly
             recognised by UK designers.

             Concrete Structures 09 provides an insight to concrete innovation, design solutions
             and project examples.




EurocodEs:                thE sustainablE                 Economic                         Visual
all changE                WholE                           concrEtE FramE                   concrEtE
Eurocode 2                More than just                  ElEmEnts                         Your questions
resources                 CO2 emissions                   A designer’s guide               answered
    Eurocode 2 Resources
    The concrete sector, through The Concrete Centre, has been leading the transition
    from British Standards to Eurocode 2 through its range of courses and publications.




    In addition, it has developed an online information resource                            document for those studying for the IStructE Chartered Membership Examination
    www.eurocode2.info and The Concrete Centre’s technical team has been                    and as a scheme design manual for building design. This publication is currently
    visiting practices to give specifically tailored in-house presentations.                being updated to Eurocode 2.

    The design guidance and resources available from The Concrete                           For more information on these publications visit
    Centre include:                                                                         www.concretecentre.com/publications

    Technical Design Guidance                                                               For information relating to Eurocode 2 guidance for precast concrete elements
    The How to series for designing to Eurocode 2 has been widely praised by                visit: www.britishprecast.org
2   structural engineers and the compendium continues to be updated. The latest
    chapter soon to be added is Chapter 12: Structural Fire Design (see page 15).           Training and CPD
    The current publication that can be viewed online at www.concretecentre.com/            Whatever you need to know, whether you have 45 minutes, a day or a specific
    publications includes previous chapters on:                                             project where you require assistance, we can help.

    •   Introduction to Eurocodes    •   Getting Started                                     CPD presentation in your office
    •   Slabs                        •   Beams                                              • Building design to Eurocode 2
    •   Columns                      •   Foundations                                        • Design of civil engineering structures to Eurocode 2
    •   Flat slabs                   •   Deflections
    •   Retaining Walls              •   Detailing                                          Many other topics refer to Eurocode 2, for more information visit
    •   BS 8500                                                                             www.concretecentre.com/cpd

    The Concise series has a new addition, Concise Eurocode 2 for Bridges. This             In house courses for Building Design to Eurocode 2
    is a sister publication to the Concise Eurocode 2 for Building Structures. Both         • Essential elements – 3.5 hours
    publications summarise the material that will be commonly used in the design of         • Theory and Background – 6 CPD hours
    reinforced and prestressed concrete bridges and concrete buildings respectively.        • Theory and Worked Examples – 6.5 CPD hours
    The Concise guides include extensive clause referencing and readers are guided          • Theory and Hands-on workshop – 13 CPD hours
    through Eurocode 2, other relevant European standards and non-contradictory
    complementary information.                                                              To request more information email buildings@concretecentre.com

    Also available to assist designers in the use of Eurocode 2 is Economic Concrete        Courses in partnership with IStructE
    Frame Elements (see page 7), this publication acts as a pre-scheme design               For more information and to book visit www.prosols.uk.com/engineers_main.htm
    handbook for the rapid sizing and selection of reinforced concrete frame elements in    Discounts available for IStructE members. Courses include:
    multi-storey buildings designed to Eurocode 2. RC Spreadsheets v3 is also updated
    to Eurocode 2 and is intended to help with the rapid production of clear and accurate   Building design to EC2 - theory and background to the UK Annex
    design calculations for reinforced concrete elements. These Excel spreadsheets          Building design to EC2 - theory and hands-on workshop
    are intended as aids for design to both BS 8110-1:1997 and Eurocode 2.
                                                                                            For further information: www.concretecentre.com/events
    For engineers requiring information on concrete behaviour and how to optimise
    the use of the material aspects of concrete there is Properties of Concrete for         Webcasts
    use in Eurocode 2.                                                                      Also available online is Optimising the Properties of Concrete to Eurocode
                                                                                            2. The filming of a recent seminar that draws on the notable features of the
    In addition there is a series of How to’s for Eurocode 6, the design of masonry         technical guidance from Properties of Concrete to Eurocode 2.
    structures and coming soon is the first volume of Worked Examples to
    Eurocode 2, and the Concrete Scheme Design Manual, which is a vital                     For more information visit www.concretecentre.com/webcasts
Contents
	 2		      Eurocode	2	Resources                                                            	 11	    Using	Visual	Concrete
           Resources to aid the transition to Eurocode 2                                            Visual concrete – your questions answered

	 3	       Eurocodes:	all	change                                                           	 12	    A	Winning	Combination
           March 2010 sees the withdrawal of BS 8110                                                Hybrid concrete construction combines the best of precast and in-situ concrete

	 4	       The	Sustainable	Whole                                                           	 14	    Higher	Strength	Concrete
           Sustainability is a complex interaction of many parts                                    Cost benefits of higher strength concretes

	 6	       Post-tensioned	approach	for	Pembury	Hospital                                    	 15	    Fire	Guidance
	          New hospital demonstrates the benefits of post-tensioned concrete                        New guidance on designing concrete structures to Eurocode 2

	 7	       Economic	Concrete	Frame	Elements	to	Eurocode	2                                  	 16	    Concrete	Information
	          Achieving the most efficient concrete frames                                             A round-up of new publications from The Concrete Centre




                                      The focus on sustainability and on the
                                                                                      Eurocodes: all change
                                      economy has increased the appreciation          March 2010 sees the withdrawal of BS 8110, it having been superseded
                                      of concrete for its potential to provide        by Eurocode 2. Although the withdrawn standard will be still be available
                                      long-term, holistic sustainable construction    and remain in the BSI catalogue for historical information purposes, it will
                                      that offers a wide range of built-in benefits   no longer be maintained by a BSI committee. This means that although BS
                                                                                      8110 will still have an acceptable level of safety it will increasingly become
                                     Increasingly, real sustainability is being       outdated and therefore will not represent current best practice. The same is
                                     seen to be greater than the sum of its           true for a number of other structural standards.
                                     constituent parts. The wide range of
                                                                                      The transition to the new Eurocodes is a major event for codified structural
        environmental and long-term performance benefits of concrete                                                                                                          3
                                                                                      design. The Concrete Centre has developed a comprehensive range of
        means that it can provide a sustainable whole. Concrete is a locally
                                                                                      resources to assist the designer with their familiarisation and use (see
        sourced product that has many inherent benefits all of which                  opposite page). These include a dedicated website, www.eurocode2.info,
        contribute to whole life sustainability.                                      a series of ‘How to’ guides and concise guides to the code as well as a
                                                                                      programme of training.
        The Concrete Centre aims to enable engineers to realise the
        benefits of concrete and so deliver the optimum structural solution.          There are of range of benefits to be gained from using the new Eurocodes. They
        Compared with other structural materials concrete offers a huge               tend to be less prescriptive and more principle-based and this allows more scope
        range of potential structural options. Tight deadlines and limited fees       for innovation. They will also harmonise research and development across the
        means that this can prove onerous for the engineer, however tools             European Community. There are also economic benefits. For concrete design it
        such as the Economic Concrete Elements to Eurocode 2, enable the              is expected that there will be material costs savings due to more efficient design
        examination of possible options quickly and efficiently. Meanwhile            allowed in the code. Furthermore, the Eurocodes are organised to avoid repetition,
                                                                                      are technically advanced and should offer more opportunities for UK-based
        resources from The Concrete Centre assist with the familiarisation and
                                                                                      designers to work throughout Europe.
        use of Eurocode 2 and so make the transition from BS 8110, much
        easier. In addition, technical guidance on construction techniques that       Designers should not be intimidated by the new Eurocodes. They are different
        are relatively new to the UK, such as post-tensioned concrete and             but not difficult. The resources available from The Concrete Centre will assist
        hybrid concrete construction, give the engineer the information and           designers to make the transition.
        confidence to examine the potential of these solutions. A network of
        regional engineers and a programme of courses and seminars further
        support this technical guidance.

        Engineers have significant demands placed upon them to provide
        the best, most cost-efficient and effective structural solution. The
        Concrete Centre has developed the resources to assist the engineer
        meet those demands.                                                           The Concrete Centre
                                                                                      Riverside House, 4 Meadows Business Park,
        Andrew Minson                                                                 Station Approach, Blackwater, Camberley, Surrey GU17 9AB
        Executive Director, The Concrete Centre                                       Tel: 01276 606800
                                                                                      www: concretecentre.com

                                                                                      The Concrete Centre is part of the Mineral Products Association, the
                                                                                      trade association for the aggregates, asphalt, cement, concrete, lime,
                                                                                      mortar and silica sand industries. www.mineralproducts.org
    The Sustainable Whole
    Sustainability is a complex whole of many constituent parts. The achievement
    of real long-term sustainability is inhibited by the concentration on traditional
    headline criteria, such as embodied CO2 and recycled contents. Other criteria
    that are evolving in significance and impact need to be given due weight.




    Recycling crushed demolition waste for use as secondary aggregate is just one part of the sustainability jigsaw.
    Photo: Tarmac



4
    A consequence of the growing recognition of the complexity of sustainability                                       Part of responsible sourcing is to allow the specifier/purchaser to identify the
    is an appreciation of the wide range of environmental benefits and credentials                                     source of the key components and therefore the conditions under which the
    of concrete construction. These arise from the material being a locally                                            material was extracted or harvested. This requires a raw material inventory
    sourced product that has many inherent benefits: robustness, durability, fire                                      management system which is also known as the ‘chain of custody’. While it
    resistance, acoustic performance, flood resilience and thermal mass – all of                                       is important to know the origins of the components it is equally important to
    which contribute to whole life sustainability. Historically, one of the main                                       know that any ‘added value’ steps in the supply chain are equally committed
    sustainability issues has been that of the embodied impact of a material.                                          to improve their sustainable performance. Certification to recognised
    However, this is only a small part of the overall picture. Indeed, the direct                                      management systems and performance reporting helps ensure that
    embodied impacts of materials only contribute to 7% of the Code for                                                consistent values are present along the supply chain.
    Sustainable Homes and to a similar amount in BREEAM assessments for
    buildings. Since concrete can make constructive contributions to whole life                                        Under the Code for Sustainable Homes and BREEAM,
    performance, notably in increased energy efficiency through its thermal mass,
    it can have a positive impact to a significant part of the remaining 93%.                                          concrete accredited to responsible sourcing standard BRE
    Responsible Sourcing                                                                                               BES 6001 can score maximum points, placing concrete
    The complexity of real sustainability is demonstrated by the issue’s ongoing
    evolution as new criteria are recognised and addressed. One such criterion is                                      on a level playing field with timber stewardship schemes.
    that of responsible sourcing. Responsible sourcing is embedded in the Code for
    Sustainable Homes and BREEAM and will almost certainly be included in the                                          The concrete industry provides employment opportunities and skill
    Code for Sustainable Buildings. It contributes about a third to the material impacts                               development to its staff throughout the UK. Responsible sourcing also
    and is likely to become more significant. The development of the BRE responsible                                   requires the demonstration of active health and safety programmes within
    sourcing standard, BES 6001 Framework Standard for the Responsible Sourcing of                                     the supply chain. Working together with the Health and Safety Executive, the
    Construction Products, provides a benchmark for construction products to gain                                      concrete industry has made significant improvements over the last decade
    credit under BREEAM and the Code for Sustainable Homes.                                                            towards its target of zero incidents.

    Concrete’s supply chain and material benefits provide it with a range of                                           The local availability of concrete and all the major components helps to
    responsibly sourced credentials. The components of concrete are extracted                                          minimise the CO2 emissions that can be associated with the transport of
    from extensive naturally occurring UK mineral deposits either in the ground                                        construction materials.
    or from the sea bed. The industry works with stakeholders and communities
    to ensure best practice is maintained during extraction and restoration to                                         Responsible sourcing is just one component part of the sustainability jigsaw.
    mitigate impacts and enhance biodiversity. The Government sets stringent                                           The sustainability strategies and management schemes being implemented
    regulations and conditions for aggregates extraction to ensure that their                                          by the concrete industry will forward the material’s built-in embedded
    supply is sustainably managed. Operating predominantly within the UK                                               credentials. This, together with its performance benefits, will ensure that
    all activities within the concrete supply chain have to conform to some                                            concrete is a solution for whole life sustainability which designers can use
    of the most stringent global environmental legislation.                                                            their skills to exploit.
The issue of sustainability and the built environment is forever developing. The
overview below is aimed at helping engineers know the current state of play.

 Strategy for Sustainable Construction, 2007

 Published by the Government and the Strategic Forum for Construction in response to European union requirements, the Strategy comprises ‘means’ and ‘ends’. One of
 the ‘means’ is the provision of 10 ecotowns, one of the ‘ends’ is a 26% reduction of UK CO2 emission, compared to 1990, by 2020.


 The direct affect of this document upon structural engineers will be seen through the Code for Sustainable Homes and the Code for Sustainable Buildings.


 Code for Sustainable Homes, 2007

 The Code comprises 9 categories. For each of these categories points are scored and the overall total results in a rating from 1 to 6, 6 being the best. In addition, higher
 ratings require achieving a certain number of points in particular categories. A subset of the material category is dictated by the BRE Green Guide for Homes.


 The impact upon structural engineers is the introduction of responsible sourced material credits and, in effect, prescription of available structural solutions if the Green
 Guide is closely followed. For example, neither the Code for Sustainable Homes or the BRE Green Guide was designed for residences over 4 storeys and hence the latter
 does not adequately cover the range nor provide useful rating comparisons for multi-storey structural solutions. For further information see ‘Concrete and the Code for
 Sustainable Homes’ and ‘Concrete and the Green Guide’ available as a free download from www.concretecentre.com/publications


 Code for Sustainable Buildings

 The Code for Sustainable Buildings has been trailed in the Strategy for Sustainable Construction. It is expected that it will be similar to BREEAM. Most structural
 engineers are aware that the maximum contribution of the Green Guide to Specification to a BREEAM score is low at typically less than 5%. It would be reasonable to
 expect a similar percentage in the Code for Sustainable Buildings.


 The impact upon structural engineers, according to a cynic, will be that they will more frequently be asked to complete sustainability questionnaires seemingly
 drafted by people who have not actually built anything. In time, hopefully, the process will improve and the expectation amongst structural engineers will be that the
 assessment is very simplistic because the structure is only a small part of the whole and also because the assessment needs to be widely applicable and yet remain             5
 usable.


 Part L (Fuel and Energy Conservation) Building Regulations

 Part L, like several Building Regulations parts, will be revised in 2010. Part L is a key tool for government to achieve its energy and CO2 targets, and once revised,
 is likely to include greater consideration of the benefits of thermal mass and more stringent criteria on overheating.


 This will mean that architects and services engineers will want to expose structural surfaces more, require good concrete finishes and even pass air through the structure
 for active cooling of slabs and walls. There may also be a move towards more solidity in facades which could then be used as vertical structure thereby eliminating
 perimeter columns. All this will have a significant impact upon structural engineers.


 Responsible Sourcing Material Credits

 Increasingly, structural engineers are getting involved in responsible sourcing of materials. The Code for Sustainable Homes (Code) and BREEAM allocate a maximum
 of around 3% for responsibly sourced materials and a similar percentage is foreseen for the Code for Sustainable Buildings. Responsible sourcing of a product means
 that environmental, social and economic criteria will have been met during the extraction/harvesting, manufacturing/processing and transport of all the necessary
 components. With concrete being a predominantly UK sourced product a lot of the criteria are already being met due to regulatory and legislative requirements.
 A major development in BREEAM and the Code is that concrete now has parity with timber in being able to achieve the maximum number of responsible sourcing
 points. The publication by BRE of BES 6001 together with the concrete industry guidance documents supports the accreditation of products to achieve these points.


 Part of the process will be to ensure that the materials and products selected for the design can demonstrate the highest level of responsible sourcing, are cost
 competitive and have security of supply. Responsible sourcing performance against the BES 6001 and BS 8902, which is currently under development, will become
 increasingly important requirements for materials and products.


 Zero Carbon Buildings

 The definition of zero carbon buildings has been much debated. The government consultation, Definition of Zero Carbon Homes and Non-Domestic Buildings, issued in
 December 2008 marks a critical stage in the transition towards zero carbon. All new homes and schools will have to be zero carbon by 2016 and other buildings by 2019.


 The effect on structural engineers will include the wider use of structure for thermal mass, more renewable power generation appendage to allow for in the structural
 design and more solid facades to reduce solar gain, which will provide different space for perimeter vertical structure.
    Post-tensioned approach for Pembury Hospital
    UK designers are increasingly taking note of the potential of post-
    tensioned (PT) suspended concrete floors.




      The clear soffits of PT slabs enable service flexibility




    PT offers several benefits, not least of which is the fact that the PT floor slabs   The structure is braced by concrete shear walls to the stair/lift cores. The
    are generally thinner than an ordinary reinforced concrete slab. They can be         structure’s height is constrained between the rock line and maximum
6
    up to 300mm thinner over one-storey than a steel frame. This minimises the           planning level restrictions hence the benefits of PT thinner floor slabs. Due
    building’s height to the extent that this could mean an extra storey on a ten-       to the sloping site and planning restrictions, the hospital has been designed
    storey building.                                                                     to vary between three and seven storeys.

    PT slabs can economically span further than a reinforced concrete slab. This in      Approximately 20% of the hospital is naturally ventilated, including most
    turn reduces the required number of columns and foundations and increases            consulting examination rooms and all of the bedrooms. Bedrooms are
    flexibility for space planning. Flexibility is further enhanced by a PT slab being   designed not to exceed 28oC for more than 50 hours a year. In addition, to
    able to accommodate irregular grids. The clear flat soffits of PT slabs enable       the thermal mass benefits of the concrete structure, the use of PT floor slabs
    complete flexibility of service layout. The absence of trimming beams around         provides generous floor-to-ceiling heights that give a light and airy feeling to
    service cores avoids conflicts between services and structure. There is also         the hospital. The hospital is due to open in 2011.
    flexibility in positioning holes through the slab because tendons are widely
    spaced and can be positioned around openings.                                        For further information see ‘Post-tensioned Concrete Floors’
                                                                                         Available as a free download: www.concretecentre.com/publications
    In addition to all the above benefits, PT equals rapid construction. There is less
    reinforcement which reduces fixing time and early stressing of the concrete
    allows the formwork to be struck quickly.
                                                                                          Project team
    The benefits of post-tensioned concrete, particularly the fast, cost-effective        Client:                              Maidstone and Tunbridge Wells NHS Trust
    construction, reduced frame height and flexibility for space planning and             Structural engineer:                 Gifford
    service layout made it an obvious structural choice for the new 512-bed,
    £227m PFI Pembury Hospital in Kent for the Maidstone and Tunbridge Wells              Architect:                           Anshen and Allen
    NHS Trust. The new seven-storey hospital, which will cover the equivalent of          Main contractor:                     Laing O’Rourke
    13 football pitches, will provide all in-patient accommodation in single en
                                                                                          Frame contractor:                    Expanded PT
    suite bedrooms, making it the first of its kind in the UK.
                                                                                          PT Specialist designer:              Alliance Design UK Limited
    The main hospital building, which has a total floor area of 66,000m2, has             PT Specialist contractor:            Strongforce Engineering
    an in-situ concrete frame on RC pad foundations with flat post-tensioned
                                                                                          M&E Engineer:                        DSSR
    bonded floor slabs of 275mm and concrete columns and retaining walls.
    Many of the concrete columns were precast off site thus further reducing the
    floor-to-floor cycle whilst providing high quality finishes. In addition, many of
    the walls adopted precast hybrid construction comprising two precast leaves
    connected by lattices of reinforcing. The wall core is cast on site to tie the
    leaves together and provide continuity at the joints. The off site manufacture
    of the column and wall elements led to improved quality, reductions in site
    labour and improved health and safety performance.
Economic Concrete Frame Elements to Eurocode 2
A new handbook published by The Concrete Centre aims to help the structural
engineer achieve the right sizes for the most efficient concrete frames.




‘Economic Concrete Frame Elements to Eurocode 2’ acts as a pre-scheme                The charts and data works on loads as follows:
design handbook for the rapid sizing and selection of reinforced concrete
                                                                                     For slabs – economic depths are plotted against span for a range of                      7
frame elements in multi-storey buildings. It is an update of the very popular
                                                                                     characteristic imposed loads.
BS 8110 version published by the Reinforced Concrete Council in 1997.
                                                                                     For beams – economic depths are plotted against span for a range of ultimate
When conceiving a design for a multi-storey structure there are many                 applied uniformly distributed loads, uaudl (uaudl is the summation of ultimate
concrete framed options which can be considered. The handbook aims to                loads from slabs, cladding, etc, with possible minor adjustment for beam
overcome the sheer volume of choice that is offered by reinforced concrete.          self-weight and cladding).
Many view this choice as being a major advantage over other structural
materials as it allows the most optimum solution to be developed. However,           For internal columns – Load:size charts are avaliable. Ultimate axial loads in
the amount of choice can make reinforced concrete a victim of its own                columns may be determined from data given for slabs and beams.
success as tight deadlines and rigorous fee competition often limits the             For perimeter columns – Moment and moment:load charts are available.
time that can be spent on examining all possible options.                            Design moments for edge and corner columns may be determined from
                                                                                     the moment charts. Moments for an assumed size are checked against the
Taking the guess-work and effort out of initial schemes when the fundamental         appropriate moment:load chart.
decisions are being made, the handbook provides charts and data that present
economic sizes for many types of concrete elements over a range of common            Example charts for slabs, beam and columns are shown in pages 8-10.
loadings and spans. The main emphasis is on floor plates as these commonly
represent 85% of superstructure costs. It does not cover lateral stability as        Design assumptions
stability is presumed to be provided by other means (e.g. by shear walls) and will   In producing the charts and data many assumptions have been made. The
be checked independently, nor does it cover foundations. The charts and data have    assumptions are more fully described in the publication but include: Design to
been derived from design spreadsheets that carry out designs to Eurocode 2 and,      EN 1992-1-1: and its National Annex. Post-tensioned design to Concrete Society
as appropriate, other Eurocodes, European and British Standards.                     TR43. Loads For slabs, 1.5kN/m2 has been allowed in addition to self-weight
                                                                                     for finishes and services. Exposure-Mild exposure conditions and one hour fire
                                                                                     resistance. Materials:In-situ C30/37 concrete, main steel FCK=500MPa. Precast as
                                                                                     determined by specialist spreadsheets. Post-tensioned C32/40 concrete and 12.9
   The handbook helps designers identify the most                                    diameter superstrand FpU=1860Mpa. Dimensions:Post-tensioned flat slabs P/A
   cost-effective option by:                                                         = 2.0MPa. Troughed slab: level soffits, 150mm wide ribs at 750 mm cc, 100 mm
                                                                                     topping, internal beam width = beam span/3.5. Flat slab: one 150 mm square hole
   • Presenting a range of feasible, economic concrete options
                                                                                     adjoining each column assumed, columns>=size indicated. If design parameters
   • Providing preliminary sizing of concrete frame elements                         stray outside these limits, the sizes and data should be used with caution. All
   • Providing first estimates of reinforcement quantities                           advice or information from The Concrete Centre is intended for those who will
   • Outlining the effects of using different types of concrete elements             evaluate the significance and limitations of its contents and take responsibility
                                                                                     for its use and application. No liability (including that for negligence) for any loss
   • Helping to ensure that the right concrete options are considered
                                                                                     resulting from such advice or information is accepted.
     for scheme design.
                     Charts for slabs, taken from Economic Concrete Frame Elements to Eurocode 2
                     In-situ slabs offer economy, versatility and inherent robustness. They can                                                                                                                                                           easy to construct. Each type has implications on overall costs, speed, self-
                     easily accommodate large and small service holes, fixings for suspended                                                                                                                                                              weight, storey heights and flexibility in use: the relative importance of these
                     services and ceilings, and cladding support details. Also, they can be quick and                                                                                                                                                     factors must be assessed in each particular case.
                                                                                                                                                                                                                 Key

                     Slabs requiring support from beams                                                                                                                                                Characteristic
                                                                                                                                                                                                     imposed load (IL)                    2.5 kN/m2                   5.0 kN/m2                     7.5 kN/m2                     10.0 kN/m2   Single span     Multiple span


                           One-way in-situ solid slabs Span: depth chart
                                                     600                                                                                                                                                                                                                                                                                             One way in-situ solid slabs are the most
                                                                                                                                                                MULTIPLE Span, m              4.0                          5.0                           6.0                         7.0                           8.0
                                                                                                                                                                                                                                                                                                                                                     basic form of slab. Deflection usually
                                                                                                                                                                Overall depth, mm
                                                     500                                                                                                                                                                                                                                                                                             governs the design and steel content is
                                                                                                                                                                IL = 2.5 kN/m²                125                          141                           167                         195                           236                               usually increased to reduce service stress
                                                                                      Single span
                                                     400
                                                                                                                                                                IL = 5.0 kN/m²                128                          156
                                                                                                                                                                                                                               Key
                                                                                                                                                                                                                                                         184                         216                           257                               and increase span capacity. Generally used
                                                                                                                                                                IL = 7.5 kN/m²                136                         166
                                                                                                                                                                                                                      Characteristic                     198                         227                           273                               for utilitarian purposes in office buildings,
                                                                                                                                                                                                                   imposed load (IL)
                                                                                                                                                                IL = 10.0 kN/m²               144                          176
                                                                                                                                                                                                                          2.5 kN/m2
                                                                                                                                                                                                                                                         206                         237                           293                               retail developments, warehouse etc.
                                                     300
                                                                                                                                                                Ultimate load to supporting beams, internal (end), kN/m
                                                                                                                                                                                                              5.0 kN/m2
                                                                                                                                                                                                                          7.5 kN/m2
                                                                                                                                                                                                                                                                                                                                                     Economic span range: 4-6m.
                          Slab depth, mm




                                                                                                                                       Multiple span
                                                                                                                                                                IL = 2.5 kN/m²                38 (19)                      50 (25)
                                                                                                                                                                                                                         10.0 kN/m2                      65 (33)                     82 (41)                       104 (52)
                                                     200
                                                                                                                                                                IL = 5.0 kN/m²                53 (27)                    71 span
                                                                                                                                                                                                                      Single (36)                        91 (45)                     113 (56)                      139 (70)
                                                                                                                                                                                                                     Multiple span
                                                                                                                                                                IL = 7.5 kN/m²                69 (35)                      92 (46)                       116 (58)                    141 (71)                      173 (87)
                                                     100
                                                        4.0         5.0         6.0         7.0            8.0           9.0     10.0           11.0     12.0   IL = 10.0 kN/m²               88 (44)                      115 (57)                      144 (72)                    175 (88)                      215 (108)
                                                                                                                                                   Span, m


                           Hollow core slabs with 50mm topping Span: depth chart
                                                     500                                                                                                                                                                                                                                                                                             Hollow core floor slabs are used in
                                                                                                                                                                Span, m                       5.0           6.0            7.0           8.0             9.0          10.0            11.0            12.0          13.0           14.0
                                                                                                                                                                                                                                                                                                                                                     conjunction with structural topping
                                                     450                                                                                                        Overall depth, mm, unpropped (propped)
                                                                                                  Unpropped                                                                                                                                                                                                                                          where enhanced performance is required.
                                                                                                                                                                IL = 2.5 kN/m²                200 (200) 200 (200) 200 (200) 200 (200) 250 (250) 300 (250) 300 (300) 350 (300) 350 (350) 400 (400)                                                    The units act compositely with in-situ
                                                     400
                                                                                                                                                                IL = 5.0 kN/m²                200 (200) 200 (200) 200 (200) 250 (250) 300 (250) 300 (300) 350 (350) 350 (350) 400 (400) 450 (450)                                                    structural topping usually 50mm thick, to
                                                     350
                                                                                                                                       Propped
                                                                                                                                                                IL = 7.5 kN/m²                200 (200) 200 (200) 250 (250) 250 (250) 300 (300) 350 (350) 350 (350) 400 (400) 450 (450)                                                              create a robust, high-capacity composite
                                                                                                                                                                IL = 10.0 kN/m²Key
                                                                                                                                                                      Characteristic
                                                                                                                                                                                              200 (200) 250 (250) 250 (250) 300 (300) 350 (300) 350 (350) 400 (400) 450 (450)                                                                        floor. Overall thicknesses are given.
                                                     300
                                                                                                                                                                  imposed load
                                                                                                                                                                Ultimate load (IL) supporting beams, internal (end), kN/m
                                                                                                                                                                               to
                                                                                                                                                                          2.5 kN/m2
                                                     250                                                                                                        IL = 2.5 kN/m²                53 (27)      64 (32)         75 (37)       86 (43)         103 (51) 121 (60) 133 (66) 154 (77) 167 (83) 190 (95)                                       Economic span range: 5-16m.
                                 Overall depth, mm




                                                                                                                                                                         5.0 kN/m  2


                                                                                                                                                                          7.5 kN/m2
                                                                                                                                                                         kN/m²
                                                                                                                                                                IL = 5.010.0 kN/m  2          72 (36)      87 (43)         101 (51) 122 (61) 142 (71) 158 (79) 182 (91) 199 (99) 225 (113) 253 (126)
                                                     200
                                                                                                                                                                        Unpropped
                                                                                                                                                                IL = 7.5 kN/m²
                                                                                                                                                                          Propped
                                                                                                                                                                                              91 (45)      109 (55) 133 (66) 152 (76) 176 (88) 203 (102) 223 (112) 253 (126) 284 (142)
                                                     150                                                                                                        IL = 10.0 kN/m²               112 (56) 140 (70) 163 (82) 192 (96) 223 (112) 248 (124) 282 (141) 317 (158)
                                                       5.0        6.0     7.0     8.0       9.0     10.0         11.0    12.0   13.0     14.0     15.0   16.0
                                                                                                                                                   Span, m


                           Two-way solid slabs Span: depth chart
                                                 600                                                                                                                                                                                                                                                                                                 Two-way solid slabs are utilitarian and
                                                                                                                                                                MULTIPLE span, m              4.0            5.0              6.0              7.0              8.0           9.0              10.0           11.0               12.0
                                                                                                                                                                                                                                                                                                                                                     generally used for retail developments,
                                                 500
                                                                                                                                                                Overall depth, mm                                                                                                                                                                    warehouses, etc. Can be difficult to form
                                                                                                                                                                IL = 2.5 kN/m²                125            125              125              141              166           191              220            250                282                 when used with a grid of downstand
                                                                                                                                                                                             Key
                                                                                                                                                                IL = 5.0 kN/m² Characteristic
                                                                                                                                                                                          125                125              137              157              183           213              243            275                313                 beams but useful where heavy loads are
                                                 400
                                                              10.0 kN                                                                                           IL = 7.5 kN/m²
                                                                                                                                                                              imposed load (IL)
                                                                                                                                                                                              125            126              148              169              199           229              262            299                335                 envisaged. Design is usually governed
                                                                                                                                                                                        2.5 kN/m2
                                                                                                  Single span                                                   IL = 10.0 kN/m²                125
                                                                                                                                                                                        5.0 kN/m2            136              158              182              213           249              284            321                360                 by deflection. Steel content is usually
                                                 300                                                                                                                              7.5 kN/m      2
                                                                                                                                                                Ultimate load to supporting beams, internal (end), kN/m                  Note: see section 8.3.4                                                                                     increased to reduce service stress and
                                                                                                                                                                                       10.0 kN/m
                                                                                                                                                                                          2
                                                                                                                                                                                                                                                                                                                                                     increase span capacity.
                        Slab depth, mm




                                                                                                                                                                IL = 2.5 kN/m²              38
                                                                                                                                                                                   Single span (19)          48 (24)          57 (29)          70 (35)          86 (43)       104 (52)         125 (62)       148 (74)           173 (87)
                                                                                                                                       Multiple span
                                                 200
                                                                                                                                                                IL = 5.0 kN/m²Multiple span (27)
                                                                                                                                                                                         53                  66 (33)          82 (41)          100 (50)         121 (60)      144 (72)         170 (85)       198 (99)           230 (115)
                                                                                                                                                                                                                                                                                                                                                     Economic span range: 6-12m.
                                                                                                                                                                IL = 7.5 kN/m²                68 (34)        85 (43)          106 (53)         129 (64)         155 (77)      182 (91)         213 (107) 247 (124) 283 (141)
                                                 100
                                                    4.0             5.0         6.0         7.0            8.0           9.0     10.0           11.0     12.0
                                                                                                                                                                IL = 10.0 kN/m²               85 (42)        108 (54)         134 (67)         162 (81)         194 (97)      229 (114) 266 (133) 306 (153) 350 (175)
                                                                                                                                                   Span, m
              8
                                                                                                                                                                                                                  Key

                     Slabs requiring support from columns                                                                                                                                               Characteristic
                                                                                                                                                                                                      imposed load (IL)                      2.5 kN/m2                    5.0 kN/m2                   7.5 kN/m2                   10.0 kN/m2   Single span      Multiple span



                           Troughed slabs Span: depth chart
                                                     700
                                                                                                                                                                MULTIPLE span, m              6.0                  7.0                 8.0                  9.0                10.0                   11.0                 12.0                      Troughed slabs are popular in spans up to
                                                                                                                                                                Overall depth, mm                                                                                                                                                                    12m as they combine the advantages of
                                                     600
                                                                                                                                                                IL = 2.5 kN/m²                250                  270                 329                  404                487                    580                  693
                                                                                                                                                                                                                                                                                                                                                     ribbed slabs with level soffits. The profile
                                                                                                                                                                                             Key                                                                                                                                                     may be expressed architecturally and/or
                                                                                                                                                                                         250
                                                                                                                                                                IL = 5.0 kN/m²Characteristic                       290                 352                  426                512                    616                  722
                                                     500                                                                                                                     imposed load (IL)
                                                                                                                                                                                                                                                                                                                                                     used for passive cooling. Economic depths
                                                                                                                                                                IL = 7.5 kN/m²                258                  301                 366                  444                538                    636                  745
                                                                                                                                                                                       2.5 kN/m2                                                                                                                                                     depend upon the widths of the beams
                                                                                                                                                                IL = 10.0 kN/m²               271                  311                 381                  465                556                    657                  773
                                                     400
                                                                                                                                                                                       5.0 kN/m2                                                                                                                                                     used. Deflection usually is critical to the
                                                                                                                                                                                       7.5 kN/m2
                                                                                                                                                                Ultimate load to supporting columns, internal (edge*) per storey, kN:                     *excludes cladding loads                                                                   beam design, which tend to be wide and
                                                                                                                                                                                    10.0 kN/m2
                         Slab depth, mm




                                                                                                                                                                IL = 2.5 kN/m²                390 (280)            545 (370)           765 (500)            1050 (655)         1400 (845)             1830 (1080)          2420 (1390)               heavily reinforced.
                                                     300
                                                                                                                                                                IL = 5.0 kN/m²                525 (350)            740 (475)           1030 (635)           1380 (825)         1810 (1060)            2350 (1340)          3030 (1700)
                                                                                                                                                                IL = 7.5 kN/m²                665 (425)            935 (575)           1280 (765)           1710 (995)         2220 (1270)            2840 (1600)          3620 (2010)               Economic span range: 6-12m.
                                                     200
                                                        6.0         7.0         8.0         9.0        10.0             11.0     12.0           13.0     14.0
                                                                                                                                                                IL = 10.0 kN/m²               830 (510)            1160 (690)          1580 (920)           2100 (1200)        2710 (1520)            3450 (1910)          4390 (2400)
                                                                                                                                                   Span, m



                           Flat Slabs Span: depth chart
                                                     600
                                                                                                                                                                MULTIPLE span, m              4.0                  5.0                 6.0                  7.0                8.0                    9.0                  10.0                      Flat slabs are quick and easy to construct,
                                                                                                                                                                Overall depth, mm                                                                                                                                                                    but punching shear, deflections and holes
                                                     500
                                                                                                                                                                IL = 2.5 kN/m²                200                  200                 206                  227                250                    286                  343
                                                                                                                                                                                                                                                                                                                                                     around columns need to be considered.
                                                                                                                                                                                             Key                                                                                                                                                     Nonetheless, flat slabs are popular for
                                                                                                                                                                                         200
                                                                                                                                                                IL = 5.0 kN/m²Characteristic                       200                 215                  246                284                    347                  427
                                                     400                                                                                                                    imposed load (IL)
                                                                                                                                                                                                                                                                                                                                                     office buildings, hospitals, hotels, blocks
                                                                                                                                                                IL = 7.5 kN/m²            200                      220                 253                  305                342                    404                  460
                                                                                                                                                                                       2.5 kN/m2                                                                                                                                                     of flats as they are quick, allow easy service
                                                                                                                                                                IL = 10.0 kN/m²               200                  236                 278                  327                399                    452                  533
                                                 300
                                                 700
                                                                                                                                                                                       5.0 kN/m2                                                                                                                                                     distribution.
                                                                                                                                                                                  7.5 kN/m      2
                                                                                                                                                                Ultimate load to supporting columns, internal (edge*) per storey, kN:                     *excludes cladding loads
                                                                                                                                                                                    10.0 kN/m2
                         Slab depth, mm




                                                                                                                                                                IL = 2.5 kN/m²                190 (95)             297 (148)           434 (217)            623 (311)          859 (430)              1179 (589)           1633 (817)                Economic span range: 4-12m.
                                                 600
                                                 200
                                                                                                                                                                IL = 5.0 kN/m²                250 (125)            390 (195)           579 (290)            836 (418)          1167 (584)             1637 (818)           2270 (1135)               Assuming column sizes are greater than
                                                 500                                                                                                            IL = 7.5 kN/m²                310 (155)            500 (250)           757 (378)            1110 (555)         1523 (762)             2085 (1042)          2748 (1374)               span/20
                                                 100
                                                                                                                                                                IL = 10.0 kN/m²               380 (190)            625 (312)           951 (475)            1375 (688)         1951 (976)             2615 (1307)          3501 (1751)
                                                    4.0             5.0         6.0         7.0            8.0           9.0     10.0           11.0     12.0
                                                 400
                                                                                                                                                   Span, m
                        Slab depth, mm




                             300
                           Post-tensioned flat slabs Span: depth chart
                                                500
                                                200                                                                                                             MULTIPLE span, m              6.0          7.0              8.0              9.0               10.0          11.0            12.0            13.0             14.0                   Post-tensioned flat slabs are ideally
                                                   6.0              7.0         8.0         9.0        10.0             11.0     12.0           13.0     14.0
                                                450                                                                                                Span, m      Overall depth, mm                                                                                                                                                                    suited to fast and economic multi-storey
                                                                                                                                                                IL = 2.5 kN/m²               200          200              200               217            249             283              318             387              515
                                                                                                                                                                                                                                                                                                                                                     construction. Used in apartment blocks,
                                                400
                                                                                                                                                                IL = 5.0 kN/m²          200
                                                                                                                                                                                         Key              200              216               249            284             320              394             508              660
                                                                                                                                                                                                                                                                                                                                                     office buildings, hospitals, hotels and other
                                                                                                                                                                                Characteristic                                                                                                                                                       similar buildings, these slabs are easy and
                                                350                                                                                                             IL = 7.5 kN/m²          200
                                                                                                                                                                             imposed load (IL)            202              235               270            307             364              464             596
                                                                                                                                                                                         2.5 kN/m2
                                                                                                                                                                                                                                                                                                                                                     fast to construct especially where there is
                                                                                                                                                                IL = 10.0 kN/m²              200          232              270               308            378             478              604
                                                300                                                                                                                                      5.0 kN/m2                                                                                                                                                   a regular column grid.
                                                600                                                                                                             Ultimate load to supporting2 columns, kN, internal (edge*), per storey: *excludes cladding loads
                                                                                                                                                                                   7.5 kN/m
                                                                                                                                                                                        10.0 kN/m2
                                                250                                                                                                             IL = 2.5 kN/m²               430 (215) 580 (290)           760 (380)         1000 (500) 1340 (670) 1750 (875) 2240 (1120) 2990 (1500) 4320 (2160)                                    Economic span range: 6-13m
                        Slab depth, mm




                                                               Key
                                                                                                                                                                                         Range for 5.0 kN/m2 multiple span
                                                500 Characteristic
                                                200
                                                   imposed load (IL)
                                                                                                                                                                IL = 5.0 kN/m²                 1.5–2.5 MPa) P/A = prestressing force/area, 1390 (695)
                                                                                                                                                                                         (PA =560 (280) 765 (385)         1030 (515) MPa                    1825 (910) 2340 (1170) 3120 (1560) 4260 (2130) 6220 (3110)                               Assuming column sizes are greater than
                                                400
                                                         2.5 kN/m2                                                                                              IL = 7.5 kN/m²               700 (350) 950 (475)           1310 (655) 1750 (875) 2270 (1140) 2960 (1480) 3980 (1990) 5360 (2680)                                                     span/19 for IL = 5.0kN/m2 etc
                                                         5.0 kN/m2
                                                150                                                                                                             IL = 10.0 kN/m²              856 (430) 1220 (610)          1670 (835) 2220 (1110) 2980 (1490) 4110 (2010) 5390 (2690)
                                                    6.0              kN/m
                                                                 7.57.0    2
                                                                                8.0         9.0       10.0              11.0     12.0       13.0         14.0
                                                 300            10.0 kN/m2
                                                                                                                                                   Span, m
                                                                 Range for 5.0 kN/m multiple span
                        Slab depth, mm




                                                                                        2

                                                                 (PA = 1.5–2.5 MPa) P/A = prestressing force/area, MPa
                                                 200


                                                 100
12.0   13.0   14.0                                  4.0             5.0         6.0         7.0            8.0           9.0     10.0           11.0     12.0
Charts for beams, taken from Economic Concrete Frame Elements to Eurocode 2
In building structures beams generally transfer loads from slabs to columns                                                                         In-situ beams offer strength, robustness and versatility, for instance in
walls. They are designed to resist resulting ultimate bending moments and                                                                           accommodating cladding support details. In overall terms for in-situ
shear forces and then checked against serviceability requirements.                                                                                  construction wide flat beams are less costly to construct then narrow deep
                                                                                                                                                    beams because the formwork is more simple to erect.
                                                                                                Key

Internal or ‘T’ beams (in-situ)                                                     Ultimate applied
                                                                                         udl (uaudl)                50 kN/m             100 kN/m                200 kN/m            400 kN/m


        ‘T’ beams, 600 mm wide web Span: depth chart
                       800
                                                                                     MULTIPLE span, m         4.0                5.0                6.0               7.0              8.0           9.0                 10.0           11.0                    12.0
                                                                                     Depth, mm
                       700
                                                                                     uaudl = 50 kN/m          250                250                276               314              388           463                 541            621                     701
                       600                                                           uaudl = 100 kN/mKey 250                     271                312               363              448           537                 627            730                     833
                                                                                           Ultimate applied
                                                                                     uaudl = 200udl (uaudl)
                                                                                                 kN/m         288                345                388               436              515           619                 727            839
                       500                                                                         50 kN/m
                                                                                     uaudl = 400 kN/m         378                456                540               626              711           798                 951
                                                                                                  100 kN/m
                                                                                                 200 supports/columns, internal (end), kN ult
                                                                                     Ultimate load tokN/m
                       400                                                                        400 kN/m
     Beam depth, mm




                                                                                     uaudl = 50 kN/m          211 (106)          264 (132)          320 (160)         378 (189)        443 (222)     511 (256)           583 (291)      657 (329)               735 (368)

                       300                                                           uaudl = 100 kN/m         411 (206)          516 (258)          624 (312)         735 (367)        852 (426)     974 (487)           1099 (549)     1230 (615)              1365 (682)
                                                                                     uaudl = 200 kN/m         814 (407)          1023 (511)         1232 (616)        1444 (722)       1662 (831)    1888 (944)          2118 (1059)    2352 (1176)
                       200                                                           uaudl = 400 kN/m         1621 (810)         2033 (1017)        2450 (1225)       2869 (1435)      3292 (1646)   3718 (1859)         4160 (2080)
                         4.0   5.0   6.0   7.0   8.0    9.0    10.0   11.0   12.0
                                                                        Span, m


        ‘T’ beams, 1200 mm wide web Span: depth chart
                       800
                                                                                     MULTIPLE span, m         6.0                7.0                8.0               9.0              10.0          11.0                12.0           13.0                     14.0

                       700
                                                                                     Depth, mm
                                                                                     uaudl = 50 kN/m          250                269                326               391              454           519                 589            662                      748
                                                                                                     Key
                       600                                                           uaudl = 100 kN/m         269                308                375               449              536           622                 715            814
                                                                                           Ultimate applied
                                                                                                udl (uaudl)
                                                                                     uaudl = 200 kN/m         314                350                428               514              609           710                 821
                       500                                                                        50 kN/m
                                                                                     uaudl = 400 kN/m         398                457                522               576              693           811
                                                                                                 100 kN/m
                                                                                                 200 supports/columns, internal (end), kN ult
                                                                                     Ultimate load tokN/m
                       400                                                                       400 kN/m
    Beam depth, mm




                                                                                     uaudl = 50 kN/m          334 (167)          394 (197)          468 (234)         548 (274)        633 (316)     723 (361)           820 (410)      924 (462)                1040 (520)

                       300                                                           uaudl = 100 kN/m         638 (319)          755 (377)          883 (441)         1018 (509)       1164 (582)    1315 (658)          1477 (738)     1648 (824)               1826 (913)
                                                                                     uaudl = 200 kN/m         1248 (624)         1466 (733)         1698 (849)        1940 (970)       2191 (1095)   2452 (1226)         2724 (1362)    3007 (1504)
                       200                                                           uaudl = 400 kN/m         2467 (1234)        2894 (1447)        3327 (1663)       3761 (1880)      4222 (2111)   4693 (2347)         5177 (2588)
                         6.0   7.0   8.0   9.0   10.0   11.0   12.0   13.0   14.0
                                                                        Span, m


        ‘T’ beams, 2400 mm wide web Span: depth chart
                       800                                                           MULTIPLE span, m         6.0                7.0                8.0               9.0              10.0          11.0                12.0               13.0                 14.0
                                                                                     Depth, mm
                       700
                                                                                     uaudl = 50 kN/m          250                250                275               324              375           429                 486                548                  613
                                                                                     uaudl = 100 kN/m
                                                                                                    Key       250                269                325               386              453           527                 597                671                  748
                       600
                                                                                                                                                                                                                                            796
                                                                                           Ultimate applied
                                                                                     uaudl = 200 kN/m
                                                                                                udl (uaudl)
                                                                                                              269                307                375               446              532           615                 703                                     895
                       500                                                           uaudl = 400 kN/m
                                                                                                 50 kN/m      317                360                419               503              593           689                 793                903
                                                                                                 100 kN/m
                                                                                     Ultimate load to supports/columns, internal (end), kN ult
                                                                                                 200 kN/m
                       400                                                           uaudl = 50 kN/m
                                                                                                400 kN/m      368 (184)          429 (214)          505 (253)         601 (301)        706 (353)     821 (411)           947 (474)          1087 (543)           1239 (619)
      Beam depth, mm




                                                                                     uaudl = 100 kN/m         668 (334)          789 (394)          935 (468)         1093 (547)       1265 (632)    1452 (726)          1647 (824)         1857 (928)           2080 (1040)
                       300
                                                                                     uaudl = 200 kN/m         1276 (638)         1509 (754)         1765 (883)        2034 (1017)      2324 (1162)   2625 (1312)         2943 (1471)        3279 (1639)          3635 (1817)
                                                                                             Multiple span
                                                                                     uaudl = 400 kN/m         2498 (1249)        2937 (1468)        3391 (1696)       3872 (1936)      4370 (2185)   4886 (2443)         5424 (2712)        5983 (2991)
                       200
                         6.0   7.0   8.0   9.0   10.0   11.0   12.0   13.0   14.0
                                                                        Span, m
                                                                                                                                                                                                                                                                               9
                                                                                                 Key

Perimeter or ‘L’ beams (in-situ)                                                     Ultimate applied
                                                                                          udl (uaudl)                  25 kN/m                50 kN/m             100 kN/m             200 kN/m



        ‘L’ beams, 300 mm wide web Span: depth chart
                       800
                                                                                     MULTIPLE span, m         4.0                5.0                6.0                7.0             8.0           9.0                 10.0               11.0                 12.0
                                                                                     Depth, mm
                       700
                                                                                     uaudl = 25 kN/m          250                250                266                307             377           455                 540                620                  700
                       600                                                           uaudl = 50 kN/m Key 250
                                                                                            Ultimate applied
                                                                                                                                 262                309                363             446           535                 630                727                  830
                                                                                     uaudl = 100udl (uaudl) 276
                                                                                                kN/m                             331                378                447             544           674                 831
                       500                                                                         25 kN/m
                                                                                                  50 kN/m 371
                                                                                     uaudl = 200 kN/m                            454                592                777
                                                                                                  100 kN/m
                                                                                     Ultimate load to supports/columns, internal (end), kN ult
                       400                                                                        200 kN/m
    Beam depth, mm




                                                                                     uaudl = 25 kN/m          106 (53)           132 (66)           159 (80)           189 (94)        221 (110)     255 (127)           291 (146)          329 (164)            368 (184)
                       300                                                           uaudl = 50 kN/m          206 (103)          258 (129)          312 (156)          367 (184)       426 (213)     487 (243)           550 (275)          615 (307)            682 (341)
                                                                                     uaudl = 100 kN/m         407 (203)          511 (255)          616 (308)          723 (361)       833 (417)     948 (474)           1069 (534)
                       200
                         4.0   5.0   6.0   7.0   8.0     9.0   10.0   11.0   12.0
                                                                                     uaudl = 200 kN/m         810 (405)          1017 (508)         1228 (614)         1444 (722)
                                                                        Span, m


        ‘L’ beams, 600 mm wide web Span: depth chart
                       800
                                                                                     MULTIPLE span, m         6.0                      7.0                      8.0                  9.0                   10.0                 11.0                      12.0
                                                                                     Depth, mm
                       700
                                                                                     uaudl = 25 kN/m          250                      270                      327                  388                   463                  529                       598
                       600                                                                   50 kN/m Key
                                                                                     uaudl =Ultimate applied 278                       306                      378                  457                   536                  622                       715
                                                                                     uaudl = 100 udl (uaudl) 312
                                                                                                 kN/m                                  364                      436                  522                   615                  719                       828
                       500                                                                          25 kN/m
                                                                                                  50 kN/m 406
                                                                                     uaudl = 200 kN/m                                  468                      524                  576                   698                  815
                                                                                                   100 kN/m
                       400
                                                                                     Ultimate load to supports/columns, internal (end), kN ult
                                                                                                   200 kN/m
  Beam depth, mm




                                                                                     uaudl = 25 kN/m          167 (83)                 197 (99)                 234 (117)            274 (137)             318 (159)            363 (182)                 412 (206)
                       300                                                           uaudl = 50 kN/m          320 (160)                377 (189)                442 (221)            510 (255)             582 (291)            658 (329)                 738 (369)
                                                                                     uaudl = 100 kN/m         624 (312)                735 (367)                850 (425)            971 (486)             1097 (548)           1228 (614)                1364 (682)
                       200
                         6.0   7.0   8.0   9.0   10.0   11.0   12.0   13.0   14.0
                                                                                     uaudl = 200 kN/m         1234 (617)               1448 (724)               1664 (832)           1880 (940)            2112 (1056)          2347 (1174)
                                                                        Span, m


        ‘L’ beams, 1200 mm wide web Span: depth chart
                       800
                                                                                     MULTIPLE span, m         6.0                7.0                8.0               9.0              10.0          11.0                12.0               13.0                 14.0

                       700
                                                                                     Depth, mm
                                                                                     uaudl = 25 kN/m          250                250                275               329              380           434                 496                566                  632
                       600                                                           uaudl = 50 kN/m Key 250
                                                                                           Ultimate applied
                                                                                                                                 269                325               387              464           538                 609                683                  760
                                                                                     uaudl = 100udl (uaudl) 269
                                                                                                 kN/m                            309                373               444              532           615                 703                796                  895
                       500                                                                         25 kN/m
                                                                                                  50 kN/m 319
                                                                                     uaudl = 200 kN/m                            361                419               503              593           691                 795                906
                                                                                                  100 kN/m
                       400
                                                                                     Ultimate load to supports/columns, internal (end), kN ult
                                                                                                  200 kN/m
    Beam depth, mm




                                                                                     uaudl = 25 kN/m          184 (92)           214 (107)          253 (126)         302 (151)        355 (178)     413 (206)           478 (239)          552 (276)            629 (315)
                       300                                                           uaudl = 50 kN/m          334 (167)          394 (197)          468 (234)         547 (273)        637 (318)     731 (365)           829 (415)          934 (467)            1047 (523)
                                                                                     uaudl = 100 kN/m         638 (319)          755 (377)          882 (441)         1016 (508)       1162 (581)    1312 (656)          1471 (736)         1639 (820)           1817 (909)
                       200
                         6.0   7.0   8.0   9.0   10.0   11.0   12.0   13.0   14.0
                                                                                     uaudl = 200 kN/m         1249 (625)         1469 (734)         1696 (848)        1936 (968)       2185 (1092)   2444 (1222)         2713 (1356)        2993 (1496)
                                                                        Span, m
              Charts for columns, taken from Economic Concrete Frame Elements to Eurocode 2
              Column design depends on ultimate axial load, NEd, and ultimate design                                                                                                                                    For an assumed column size, this moment and the ultimate axial load are
              moment, MEd. For internal columns moments may generally be assumed                                                                                                                                        used to interrogate moment:load charts – firstly to check the validity of the
              to be nominal. Therefore the design chart for braced internal columns                                                                                                                                     assumed column size and secondly to estimate the amount of reinforcement
              (Figures A and B) give square sizes against total ultimate axial load NEd for                                                                                                                             required in that column size (as illustrated in Figures C and D). Some iteration
              a range of reinforcing steel contents for to concrete grades for both in-situ                                                                                                                             may be required.
              and precast columns.
                                                                                                                                                                                                                        As a first step, edge and corner columns sizes may be estimated from Figures
              However, in perimeter columns moments are generally critical. In the                                                                                                                                      A or B adjusting the axial load by:
              publication, charts are provided so that first order moments, M, in edge
              and corner columns may be estimated. For in-situ columns this is according                                                                                                                                •          Adding 50% of axial load for edge columns
              to whether they occur in beam-and-slab or flat slab construction.                                                                                                                                         •          Adding 150% of axial load for in--situ corner columns
                                                                                                                                                                                                                        •          Adding 80% of axial load for precast corner columns


                                                                                                              Key

              Internal Columns                                                                         Percentage
                                                                                                    reinforcement           0.2%        1.0%              2.0%                                             3.0%                  4.0%




                                                  Figure A: Load:size chart for internal columns, C30/37                                                                                                                                                 Figure B: Load:size chart for internal columns, C40/50


                Key                               800
                                                                                                                            0.2%
          Percentage
      reinforcement
               0.2%                               700                                                                                                                                                           Key
                                                                                                                                                    1.0%
               1.0%
                                                                                                                                                                                                          Percentage                                     600
                                                                                                                                                                                                       reinforcement
               2.0%                                                                                                                                 2.0%                                                                                                                                                  Min.
                                                  600                                                                                                                                                              Min.                                  550                                                     1.0%
               3.0%                                                                                                                                 3.0%                                                                                                                                                           2.0%
                                                                                                                                                                                                                  1.0%                                                                                                3.0%
               4.0%                                                                                                                                 4.0%                                                                                                 500                                                            4.0%
                                                                                                                                                                                                                  2.0%
                                                                                                                                                                                                                                                                                                                              C50/60
                                                                                                                                                                                                                                                                                                                         4.0% C40/50
                                                  500                                                                                                                                                             3.0%                                   450
                                                                                                                                                                                                                  4.0%
                                                                                                                                                                                                       4.0% C50/60
                                                                                                                                                                                                                                                         400
                                                  400
                                                                                                                                                                                                                                      Size, mm square




                                                                                                                                                                                                                                                         350
                               Size, mm square




                                                                                                                                                                                                                                                         300
                                                  300
  10                                                                                                                                                                                                                                                     250

                                                  200                                                                                                                                                                                                    200
                                                                            0         1000 2000 3000 4000 5000 6000 7000 8000 9000 10000                                           Figure 4.19a                                                                0    1000 2000     3000   4000   5000   6000   7000 8000      9000 10000
        Figure 3.35                                                                                                                                                          Load:size chart for                                                                                                        Ultimate axial load, NEd, kN
Load :size chart for                                                                                                                                 , kN
                                                                                                                             Ultimate axial load, NEdprecast internal columns
  internal columns




              Perimeter Columns: Example

                                                  Figure C: Moment deviation chart for edge column                                                                         Figure D: Moment:load chart for edge columns
                                                  in flat slab construction                                                                                                in flat slab construction

                                                  150                                                                                                                      3000
                                                                                                                                                                                                                             Mmin                                                               For the case of an assumed
                                                  125                                                                                                                                                                                                                                           300mm square edge column in
                                                                                                                                                                           2500 3000
                                                                                150
                                                                                                                                                                                                                            Mmin                                                                a flat slab, where the bays are
                                                  100                                                                                                                      2000 2500                                                                                                            75m square, the imposed load
                                                                                125
                                                                                                                                                                                                   2000
                                                                                                                                                                                                                                                                                                = 5.0 kN/m2 , FCK = 30 MPa and
                          Column moment, M, kNm




                                                   75                           100
                                                                                                                                                                           1500                                                                                                                 NED = 1000kN. The moment in
                                                                                                                                                                                                   1500
                                                                                                                                                                                                                                                                                                the column is assessed as being
                                                    Column moment, M, kNm




                                                                                75
                                                                                                                                                     Axial load, NEd, kN




                                                   50
                                                                                                                                                                             Axial load, NEd, kN




                                                                                50
                                                                                                                                                                           1000 1000                                                                                                            100kNm from Figure C and
                                                                                25
                                                                                                                                                                                                    500
                                                                                                                                                                                                                  0.5% 1%
                                                                                                                                                                                                                  0.5% 1%
                                                                                                                                                                                                                   (min.)
                                                                                                                                                                                                                                    2%
                                                                                                                                                                                                                                             2%
                                                                                                                                                                                                                                                    3%       4%
                                                                                                                                                                                                                                                            3%       4%                         from Figure D the amount of
                                                   25                                                                                                                       500                                   (min.)
                                                                                                                                                                                                       0
                                                                                                                                                                                                                                                                                                reinforcement is assessed as being
                                                                                 0

                                                      0
                                                                                      4   6     8          10          12
                                                                                                                                                                                                           0    20 40       60   80 100 120 140 160 180
                                                                                                                                                                                                                                                                                                3.0% (as shown by the black line).
                                                                                                            Slab span, m                                                             0
                                                                                                                                                                                    300 mm square                                                       Moment, M, kNm
                                                             300 mm square
                                                                            4             6           8  10          12                                                                            0           20 40        60      80 100 120 140 160 180
                                                  Figure 3.41                                                                                                              Figure 3.42
                                                                                                          Slab span, m                                                                                                    Moment,
                                                                                                                                                                           Moment:load charts for edge columns in flat slab                                              M, kNm
                                   300 mm square  Moment derivation charts for edge columns in flat slab                                                    300 mm square  construction
                                                  construction

                       Figure 3.41
                               Key                                                                                                                 Figure 3.42
                                                                                                                                                          Key
                                derivation charts for edge columns in flat slab
                       MomentBeam uaudl                                                                                                                   Percentage reinforcement
                                                                                                                                                   Moment:load charts for edge columns in flat slab
                                        2    5 kN/m2    7.5 kN/m2
                                   2.5
                       construction kN/m                          10 kN/m2                                                                                    Min.
                                                                                                                                                   construction            1.0%    2.0% 3.0%     4.0%
                                                                  Columns below only                Columns above & below                                                                   fck = 30 MPa                         fck = 50 MPa


                       Key                                                                                                                         Key
                       Beam uaudl                                                                                                                  Percentage reinforcement
                                        2.5 kN/m2     5 kN/m2                                             7.5 kN/m2     10 kN/m2                                  Min.         1.0%                                                2.0%          3.0%                        4.0%
                                        Columns below only                                                Columns above & below                                   fck = 30 MPa                                                      fck = 50 MPa
              C H Goodchild, R M Webster and K S Elliot, Economic Concrete Frame Elements to Eurocode 2, The Concrete Centre, 2009
Answering your questions
on how to achieve high quality visual concrete
Increasingly, designers want to expose in-situ or precast concrete structures                                Is there anything else that I should do to ensure a quality finish?
and make them visual. This is for a variety of reasons including increased                                   Many factors can affect the final finish and visual look, these include:
thermal mass, provision of low maintenance finishes and structural aesthetics.
                                                                                                                                                                                             11
However, making concrete ‘visual’, particularly for on site construction, gives                              • Panel layouts: the joints between the formwork panels will often be
rise to a number of specification questions, some of which are addressed below.                                visible. The architect should make clear how the panels should be laid
                                                                                                               out in order to meet the project brief.
What type of formwork should I use?                                                                          • Spacers: the reinforcement spacers should be chosen to minimise
The type of formwork that should be used depends upon the required finish.                                     visual impact.
If a particular finish, such as board marking, is required then clearly the                                  • Falsework: deflection of the formwork and falsework under the weight
appropriate formwork should be used. If you are seeking a plain, flat finish                                   of the concrete will be visible in the final finish and can be particularly
then ideally you should describe the finish required in terms of permissible                                   noticeable in plain finishes. The falsework design should minimise
blemishes and irregularities and seek recommendations from the formwork                                        potential deflections.
supplier. For further information there are two major standard in-situ concrete
finish description specifications.1,2                                                                        Can I eliminate blemishes?
                                                                                                             High quality finishes are successfully achieved in concrete. However, a
Do I need special concrete?                                                                                  completely uniform and blemish-free concrete finish as struck is unrealistic.
Concrete is usually specified by the structural engineer based on strength                                   Some blemishes are unavoidable and should be considered as being part
and durability requirements. However, for visual concrete the mix design will                                of the visual character of concrete. If a completely blemish-free surface is
often have to be adjusted to aid placing and compaction in order to achieve                                  required then the designer should consider a plain concrete finish, allow for
a consistent quality finish. The location of the project will be an important                                blowholes to be filled and the surface made good with a finishing coat.
factor because the constituents of concrete are locally sourced and vary
depending on the local geology. Concrete suppliers experienced in producing                                  For further information on visual concrete visit: www.concretecentre.com
visual concrete will be able to offer advice for particular projects.

A coordinated concrete specification should be prepared giving both structural
and architectural requirements. It is best practice at the early stages of a
project to consider having test panels made up.




1. National Building Specification. NBS Building, BNBS 2008
2. CONSTRUCT. National Structural Concrete Specification for Building Construction. Concrete Society 2004.
     A Winning Combination
     Hybrid concrete construction (HCC) combines the benefits of precast
     concrete with those on in-situ concrete thereby enabling the optimum
     structural solution to be realised.




     Precast column and floor units with cast in-situ beams. Homer Road, Sollihull.                               In-situ columns or walls and beams with precast floor units. West Quay car park, Southampton
     Photo: Foggo Associates                                                                                      Photo: Hanson Concrete Products


     The overall advantage of HCC is that it brings together the particular benefits                          Hybrid options
     of precast and in-situ concrete into one total solution. These solutions                                 The ideal combination of precast and in-situ concrete is influenced by project
12   tend to be simple, buildable and cost effective and result in safer and faster                           requirements. There is a wide range of possible options. A current
     construction. The benefits of HCC are summarised below:                                                  UK representation of these and their benefits are highlighted below:


     Table1: Benefits of hybrid concrete construction                                                         n In-Situ n Precast


           Precast concrete                        Precast or                         In-situ concrete
                                                in-situ concrete

                Economic for                                                            Economic for
                                              Inherent fire resistance
             repetitve elements                                                         bespoke areas


              Long clear spans                        Durability                          Continuity                          Type 1                                        Type 2
                                                                                                                 Precast twin wall and lattice girder           Precast column and edge beam
                                                                                                                     slab with in-situ concrete                      with in-situ floor slab
             Speed of erection                     Sustainability                     Inherent robustness



                  Buildability                Acoustic performance                        Flexibility

                                              Thermal mass that can
                                                                                 Servics coordinatoin later
           High-quality finishes               be utilised for fabric
                                                                                       in programme
                                                 energy storage
                                                                                                                               Type 3                                        Type 4
                                                                                        Locally sourced
             Consistent colour                      Prestressing                                                   Precast column and floor units             In-situ columns or walls and beams
                                                                                           materials
                                                                                                                      with cast in-situ beams                        with precast floor units


                   Accuracy                         Mouldability                      Short lead-in times


                                                   Low vibration
        Reducted propping on site
                                                   characteristics

               Reduced skilled
                labour on site                                                                                                  Type 5                                       Type 6
                                                                                                                    In-situ column and structural                 In-situ columns with lattice
                                                                                                                     topping with precast beams                    girder slabs with optional
                                                                                                                            and floor units                          spherical void formers
Table 2: Specific benefits for typical HCC options
                      Ease of services




                                         storey height




                                                                                                                                                    construction
                                                                                                                                 Soffit can be
                                                                        Clear Spans




                                                                                                                                                                   Temporary
                                                                                                                                                    Maximises
                                                                                      Deflection




                                                                                                                                                                   minimised
                                                         Suitability
                                         Minimises




                                                                                                               materials
                                                                                                               Minimise
                                                         for holes




                                                                                                                                 exposed



                                                                                                                                                    off-site
                                                                                      control




                                                                                                                                                                   works
     Type 1          aa                  aa              aa            m              aa                         a               aa                     a           aa
     Type 2          aa                  aa                a           aa                 a                      a                 a                    a             m
     Type 3           a                  aa                a           aa             aa                      aa                    m                   aa          aa
     Type 4           a                  aa                a           aa             aa                      aa                    m                   a           aa
     Type 5            m                    m              a           aa             aa                      aa                    m                   aa          aa
     Type 6          aa                     a              a           aa                 m                   aa                 aa                     a             a

     KEY aa Excellent                       a Good            m Can be used




Design
The initial sizing of the elements for HCC can be carried out using normal
methods (see page 7). These elements can be designed as for a normal                                                                                                           13
reinforced concrete building, with full composite action between in-situ and
precast elements. The design should also consider the construction phase, for
instance one of the load cases could be precast concrete elements supporting
the weight of wet in-situ concrete. An additional stage may be considered if
de-propping happens before the in-situ concrete develops its design strength.

The interface between precast and in-situ concrete elements should be
considered in the design process. Particular areas to consider are bearings,
movements, differential shrinkage and restraint.

Procurement
Many UK engineers are experienced in using in-situ concrete, but would feel
less confident specifying precast concrete. However, the UK precast industry
has years of experience working on a vast range of projects. To obtain the
maximum benefit of this experience, it is advisable to involve the precast
concrete manufacturer at the earliest opportunity. The precast industry is            Precast twin wall and lattice girder slab with in-situ concrete
pleased to give initial advice.                                                       Photo: John Doyle Construction Ltd


                                                                                      Further guidance
A Partners in Innovation research project was carried out to identify best
                                                                                      The Concrete Centre has developed a number of resources to assist
practice in the procurement of HCC. The research found that the benefits
                                                                                      designers in making the most of HCC.
result from:
                                                                                      •    Hybrid Concrete Buildings – General guidance on HCC that explains
•   early involvement of specialist contractors
                                                                                           the benefits of the components and the options presented here.
•   using a lead frame contractor
                                                                                      •    Design of Hybrid Concrete Buildings – A detailed design guide written
•   using best value philosophy
                                                                                           for the structural engineer using HCC for the first time.
•   holding planned workshops
                                                                                      •    Best Practice Guidance for Hybrid Concrete Construction – A guide
•   measuring performance
                                                                                           to using the results of the research into procurement of HCC.
•   trust
•   close cooperation – with an emphasis on partnering.
                                                                                      These publications are available for download from The Concrete Centre
                                                                                      website, visit: www.concretecentre.com/publications
     Using higher strength concretes can offer
     distinct cost benefits
     There are cost benefits to be gained by using higher strength concretes for
     tall buildings. This can be shown by comparing three alternative options to
     the base option of a reinforced concrete frame using C32/40 concrete.

     The Concrete Centre has commissioned a number of cost model studies that             Table 1 shows that the most cost effective option in terms of overall
     compare the overall building costs when a variety of steel and concrete frames       building cost is option 2, C50/60 concrete throughout, which would save
     are used. The studies cover offices, schools, hospitals and, soon to be published,   nearly £30,000 on a £14.4M building. The increase in the net lettable area
     a 21-storey residential building. The residential study shows that the in-situ       has been shown for each option too. It is not possible to evaluate this in
     concrete flat slab option with concrete columns gives the lowest cost building.      monetary terms because it will vary from project to project. Unsurprisingly,
                                                                                          the biggest increase in floor area comes from using the highest
     A further study using alternative concrete classes to the base option of             strength concrete.
     Class C32/40, has been undertaken to establish the benefits of using higher
     strength concrete.                                                                   In general terms, member companies of the British Ready-Mixed Concrete
                                                                                          Association, part of the Mineral Products Association, can produce and
     Option 1 uses a class C50/60 concrete to reduce the cross section of the             supply C50/60 class concrete or above from any ready-mixed concrete
     vertical elements. The reduced area of the walls is due to their increased           plant, given sufficient notice and preparation time.
     stiffness arising from the higher strength concrete having an increased
     elastic modulus.                                                                     Carrying out these comparisons, it would appear to show that by using a
                                                                                          C50/60 concrete throughout the structure, savings can be made in the overall
14   Option 2 uses the C50/60 concrete for the slabs as well as the walls. When           frame cost as well as for other building elements. Using the same concrete
     designing to Eurocode 2 the increased stiffness of the higher strength               mix throughout makes the construction easier too. Finally, it is worth noting
     concrete can be used to reduce the deflection or to reduce the depth for             that Eurocode 2 treats it as a normal strength concrete so this means that the
     the same deflection (an effect that was ignored in BS 8110). By reducing             engineer does not have to make special provisions in the design. Consideration
     the slab thickness there are savings to be made in other elements of the             of the increase in the net lettable area may show that Option 3 is even more
     building, for instance the area of the cladding and the internal partitions;         cost effective.
     saving materials and therefore reducing the overall building cost.
                                                                                          Table 1
     Option 3 makes use of a C60/75 concrete to reduce the volume of the
                                                                                          Comparison of thee high strength concrete options.
     vertical elements still further and is used in combination with a C50/60
     concrete for the floors. This option minimises the floor area of the verticals,
     but uses a higher strength concrete for the slabs to avoid having a large                                     Base
                                                                                                                               Option 1        Option 2     Option 3
     differential in concrete strength at the slab/column junction.                                               Option

                                                                                              Concrete class
                                                                                                                  C32/40         C32/40         C50/60       C50/60
                                                                                                 for slab

                                                                                            Concrete class for
                                                                                                                  C32/40         C50/60         C50/60       C60/75
                                                                                            vertical elements

                                                                                              Change from
                                                                                                                     £0          £-4,190        £-9,650       £-200
                                                                                              base option

                                                                                                Change in
                                                                                                                     £0            £0          £-16,120     £-16,120
                                                                                              cladding cost

                                                                                            Change in internal
                                                                                                                     £0            £0           £-4,040      £-4,040
                                                                                             partition costs

                                                                                              Total change
                                                                                                                     £0         £-4,190        £-29,810     £-20,360
                                                                                                in costs

                                                                                              Change in net
                                                                                                                   0.0%           1.2%           1.2%         1.8%
                                                                                              lettable area
                                                                                                 Concrete is a non-combustible
                                                                                                 material that has a slow rate of heat
                                                                                                 transfer. For most applications it can
                                                                                                 meet the required fire resistance
                                                                                                 without the need for any additional
                                                                                                 measures and design.




Fire Guidance
To aid the transition to Eurocode 2, The Concrete Centre is publishing new guidance: ‘How to
Design Concrete Structures using Eurocode 2 – Structural Fire Design’. This new guide is the
12th part of the popular ‘How to’ series of guides to Eurocode 2.
                                                                                                                                                                 15
Fire design to Eurocode 2, Part 1 – 2 can be approached in three ways:             The final option for simplified calculations is the zone method. This is
• Tabular methods                                                                  considered to be a more accurate approach than the isotherm method,
• Simplified calculation methods                                                   especially for columns. Concrete in the ineffective zone at fire exposed
• Advanced calculation.                                                            surfaces is ignored and the remaining section is divided up into parallel
                                                                                   rectangular zones. The properties and behaviour for each zone is calculated
Tabular methods                                                                    and used to determine the overall resistance.
The tables generally allow the designer to look up minimum dimensions and
cover for a particular type of element. There are a number of tables covering      Advanced calculation
all the typical elements, but some do come with limitations and here the           The advanced methods are for use by specialists. Further guidance on the
‘simplified calculation methods’ may have to be used.                              performance of concrete in fire including use of advanced methods is given
                                                                                   in the forthcoming Concrete Centre publication ‘Guide to the Performance
Simplified calculation methods                                                     of Concrete Structures in Fire’.
There are a number of simplified methods available. For beams and slabs it
allows the designer to determine whether the axis distance (the distance from      Recommended reading:
the face of the concrete to the centre of the bar under consideration) can be      1. Fraser, A.S and Jones, A.E.K., How to design concrete structures using
justified and this is based on detailed examination of the flexural capacity. It      Eurocodes2 – Structural Fire Design. The Concrete Centre, 2009.
does not allow the designer to reduce the minimum section size.                    2. British Standards Instutition. BS EN 1992-1-2, Eurocode 2: design of
                                                                                      concrete structure. General Rules – structural fire design. BSI, 2004.
For structural members that are subject to axial loads and where their             3. Baily,C and Khoury, G. Guide to the performance of concrete structures
behaviour is influenced by second order effects, there is a calculation method        in fire. The Concrete Centre, 2009
(Annex B.3) but given its complexity tables have also been produced (Annex
C). This approach is particularly useful for columns which fall outside the        For information on publications from The Concrete Centre,
limitation on eccentricity for the column tabular methods.                         visit: www.concretecentre.com/publications

The isotherm method assumes that all concrete that has reached a critical
temperature of 500oC should be neglected and that the section resistance
can be based on the rest of the concrete which is assumed to retain its full
strength. The section resistance can then be calculated in the normal way.
Concrete information
The Concrete Centre is the central development organisation for the UK concrete industry. Its aim is to assist all those involved in design and construction to
realise the full potential of concrete. In particular, The Concrete Centre offers a comprehensive range of publications, seminars, and courses and online resources.
For further information visit: www.concretecentre.com

The Concrete Centre has published a number of titles that can assist designers in achieving optimum structural solutions. Downloads or ordering details of all of
the publications feature below can be found on: www.concretecentre.com/publications




                   Design of Hybrid Concrete Buildings                                                    Concrete Logistics

                   This design guide is intended to provide the structural engineer                       The UK is unusual in its preponderance of the ubiquitous
                   with essential guidance for the design of structures that                              steel shed. However, this could change as the demand for
                   combine precast and in-situ concrete in a hybrid concrete                              ever more cost-effective construction of industrial buildings is
                   structure. It introduces the options available for hybrid concrete                     coupled with a number of construction drivers that question
                   structures and goes on to explain the key considerations in the                        the assumption that steel portal frames and cladding offer the
                   design of this type of structure.                                                      best structural solution. This publication outlines the benefits
                                                                                                          of concrete construction for industrial buildings including
                                                                                                          flexibility, speed of construction and long-term performance.




                   Cost Model Study – School Buildings                                                    School Construction

                   This publication covers a comprehensive and independent                                Concrete construction can provide cost-effective, comfortable,
                   cost study comparing six structural frame options for a typical                        flexible and fire resistant schools, with good acoustics and
                   secondary school. Budget costings were assigned to all elements of                     minimal vibration. This publication covers concrete solutions for
                   construction and adjustments were made to reflect time-related                         school construction. Four case studies are also included, one of
                   costs attributable to differences in the construction programme.                       which is a detailed cost comparison on school design.
                   There was a relatively small cost variation between the options.
                   However, the study highlighted the extent to which elements other                      Also available:
                   than the structure can be affected by the frame material chosen.                       • Hospital Construction
                                                                                                          • Concrete Framed Buildings
                   Also available:
                   • Cost Model Study – Hospitals
                   • Cost Model Study – Commercial Buildings




                   Concrete Credentials: Sustainability                                                   Thermal Mass Explained

                   Concrete is the robust construction material that provides a                           Until recently, the use of thermal mass was often disregarded
                   vital resource in the development of sustainable solutions. The                        in favour of a largely services based solution to the heating and
                   UK is almost completely self-sufficient in concrete and the                            cooling of buildings, which is not suprising in an age when cheap
                   constituent materials needed for its manufacture, which makes                          energy was plentiful and the effects of climate change had yet
                   it, both economically and environmentally, an option for any                           to be felt. However, the time to re-evaluate the contribution
                   project. The tables within this document present the perfor-                           that thermal mass can make to building performance has come.
                   mance benefits of concrete that designers can utilise to create                        To do this, it is important to have a basic working knowledge
                   sustainable projects and sustainability credentials of concrete                        of thermal mass and how to best use it. That is the purpose of
                   products and their constituent materials.                                              this guide

                                                                                                          Also available:
                                                                                                          • Utilisation of Thermal Mass in Non-Residential Buildings




                         To download these free publications visit www.concretecentre.com/publications