Supply and Erection of Prestressed Concrete Girders by iih17598

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   Supply and Erection of
Prestressed Concrete Girders




                        MRS11.75
                            12/99
Department of Main Roads                                                                                                                   MRS11.75
Standard Specification                                                  Supply and Erection of Prestressed Concrete Girders



                                                   Table of Contents
                                                                                                                                                         Page

1   INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.1

2   MEASUREMENT OF WORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.1
    2.1 Standard Work Items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.1
    2.2 Work Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.1

3   DEFINITION OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.2

4   QUALITY SYSTEM REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.2
    4.1 Hold Points, Witness Points and Milestones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.2
    4.2 Construction Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.2

5   PRESTRESSED CONCRETE GIRDERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                  75.3
    5.1 Supply of Girders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .             75.3
    5.2 Manufacture of Prestressed Concrete Girders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                               75.3
    5.3 Girders Supplied by the Principal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                     75.3
        5.3.1 Supply Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .               75.3
        5.3.2 Time of Delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                75.3
        5.3.3 Acceptance of the Girders by the Contractor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                 75.3
        5.3.4 Damage to Girders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                 75.3
    5.4 Handling, Transport and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                       75.3
        5.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         75.3
        5.4.2 Lifting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         75.3
        5.4.3 Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .           75.4
              5.4.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                 75.4
              5.4.3.2 Certification of Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                           75.4
              5.4.3.3 Mass of Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                     75.4
              5.4.3.4 Escorts and Pilots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                      75.4
              5.4.3.5 Support of Girders During Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                   75.4
        5.4.4 Support of Girders During Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                           75.4

6   MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         75.4
    6.1 Cement Mortar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .             75.4
    6.2 Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        75.4
    6.3 Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    75.4
    6.4 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     75.4
    6.5 Proportions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         75.4
    6.6 Epoxy Putty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         75.4
    6.7 Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      75.4
    6.8 Girder Restraint Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                 75.4
    6.9 Girder Restraint Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                75.5

7   ERECTION OF PRESTRESSED CONCRETE GIRDERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                                  75.5
    7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       75.5
    7.2 Installation of Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .              75.5
        7.2.1 Preparation of Bearing Seat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                     75.5
        7.2.2 Installation of Laminated Elastomeric Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                  75.5
        7.2.3 Installation of Pot-Type Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                         75.5
    7.3 Installation of Prestressed Concrete Girders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                          75.5
        7.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         75.5
        7.3.2 Seating Girders on Laminated Elastomeric Bearings . . . . . . . . . . . . . . . . . . . . . . . . . .                                       75.5
        7.3.3 Seating on Pot-Type Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                        75.5
        7.3.4 Fixed End Restraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                  75.6

                                                                                                                                                 Page i of ii
                                                                                                                                                 MRS11.75
                                                                                                                                                     12/99
MRS11.75                                                                                                        Department of Main Roads
Supply and Erection of Prestressed Concrete Girders                                                                Standard Specification



                                                      Table of Contents
                                                                                                                                               Page
                    7.3.5 Temporary Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.6

8         LOADING OF T GIRDERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.6

9         CAST IN SITU DECK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.6




    Page ii of ii
    MRS11.75
    12/99
Department of Main Roads                                                                               MRS11.75
Standard Specification                                Supply and Erection of Prestressed Concrete Girders

Supply and Erection of Prestressed
Concrete Girders
1            INTRODUCTION                                    2.2       Work Operations
This specification applies to the supply and/or              Item 8201        Prestressed concrete I girders,
erection of prestressed concrete I girders and                                supply on Site, [depth] mm deep,
prestressed concrete T girders for a bridge                                   [length] metres long
superstructure.                                              Item 8211        Prestressed concrete T girders,
This specification shall be read in conjunction with                          supply on Site, [girder type], [depth]
Standard Specifications MRS11.01 Introduction to                              mm deep, [length] metres long
Standard Specifications, MRS11.50 Specific Quality           These items are used only where prestressed concrete
System Requirements and other specifications as              girders are supplied by the Contractor. Work
appropriate.                                                 Operations incorporated in the above items include —
This specification forms part of the Standard                (a)   Work Operations listed in Clause 2.2.5 of
Specifications Roads Manual.                                       MRS11.01 Introduction to Standard
                                                                   Specifications;
2            MEASUREMENT OF WORK                             (b)   Manufacture of prestressed concrete girders;
2.1          Standard Work Items                             (c)   Transport to the Site;
                                                             (d)   Preparation of the Site storage area;
In accordance with the provisions of Clause 2 of
MRS11.01 Introduction to Standard Specifications,            (e)   Unloading at the Site; and
the Standard Work Items incorporated in this                 (f)   Storage at the Site.
specification are listed in Table 1.
Table 1 - Standard Work Items
 Standard                                                                                           Unit of
                                                Description
 Item No.                                                                                         Measurement
                                      Prestressed Concrete I Girders
      8201      Prestressed concrete I girders, supply on Site, [depth] mm deep, [length]               each
                metres long
      8202      Transport of prestressed concrete I girders to the Site, [depth] mm deep,               each
                [length] metres long, ex works [location]
      8203      Erection of prestressed concrete I girders, [depth] mm deep, [length]                   each
                metres long
                                     Prestressed Concrete T Girders
      8211      Prestressed concrete T girders, supply on Site, [girder type], [depth] mm               each
                deep, [length] metres long
      8212      Transport of prestressed concrete T girders to the Site, [girder type], [depth]         each
                mm deep, [length] metres long, ex works [location]
      8213      Erection of prestressed concrete T girders,[girder type], [depth] mm deep,              each
                [length] metres long
                                                  Bearings
      8221      Laminated elastomeric bearings, [length] x [breadth] x [depth]                          each
      8222      Pot-type bearings, [rated load capacity], [fixed / sliding]                             each
                                             Girder Restraints
      8231      Girder restraints                                                                       each


                                                                                                        Page 75.1 of 6
                                                                                                           MRS11.75
                                                                                                                12/99
MRS11.75                                                                          Department of Main Roads
Supply and Erection of Prestressed Concrete Girders                                  Standard Specification

Item 8202          Transport of prestressed concrete I     (a)   Work Operations listed in Clause 2.2.5 of
                   girders to the Site, [depth] mm deep,         MRS11.01 Introduction to Standard
                   [length] metres long, ex works                Specifications;
                   [location]                              (b)   Supply and fabrication of bearings including
Item 8212          Transport of prestressed concrete T           compensator plates, where required;
                   girders to the Site, [girder type],     (c)   Supply of holding-down bolts and sockets;
                   [depth] mm deep, [length] metres
                   long, ex works [location]               (d)   Protective coating of bearings;

These items are used only where prestressed concrete       (e)   Testing of bearings;
girders are supplied by the Principal for collection by    (f)   Supply of epoxy putty;
the Contractor at the place of manufacture. Work
                                                           (g)   Preparation of bearing seat; and
Operations incorporated in the above items include —
                                                           (h)   Installation of bearing.
(g)    Work Operations listed in Clause 2.2.5 of
       MRS11.01 Introduction to Standard                   Item 8231     Girder restraints
       Specifications;
(h)    Taking delivery of girders at the location and      Work Operations incorporated in the above item
       by the mode nominated in the schedules;             include —
(i)    Transport to the Site;                              (a)   Work Operations listed in Clause 2.2.5 of
                                                                 MRS11.01 Introduction to Standard
(j)    Unloading at the Site; and                                Specifications;
(k)    Storage at the Site.                                (b)   Supply and fabrication of girder restraint
                                                                 angles and fastening bolts, nuts and washers;
Item 8203          Erection of prestressed concrete I
                   girders, [depth] mm deep, [length]      (c)   Supply of epoxy putty;
                   metres long                             (d)   Temporary installation during erection of
Item 8213          Erection of prestressed concrete T            girders; and
                   girders,[girder type], [depth] mm       (e)   Permanent installation after completion of
                   deep, [length] metres long                    deck.
Work Operations incorporated in the above items
include —                                                  3         DEFINITION OF TERMS
(a)    Work Operations listed in Clause 2.2.5 of           The terms used in this specification shall be as
       MRS11.01 Introduction to Standard                   defined in Clause 3 of MRS11.01 Introduction to
       Specifications;                                     Standard Specifications.
(b)    Removal of advertising labels; and
(c)    Installing girders on substructure.                 4         QUALITY SYSTEM REQUIREMENTS

Item 8221          Laminated elastomeric bearings,         4.1       Hold Points, Witness Points and
                   [length] x [breadth] x [depth]                    Milestones

Work Operations incorporated in the above item             General requirements for Hold Points, Witness
include —                                                  Points and Milestones are specified in Clause 5 of
                                                           MRS11.01 Introduction to Standard Specifications.
(a)    Work Operations listed in Clause 2.2.5 of
       MRS11.01 Introduction to Standard                   The Hold Points, Witness Points and Milestones
       Specifications;                                     applicable to this specification are summarised in
                                                           Table 2.
(b)    Supply of bearings;
(c)    Supply of epoxy putty;                              4.2       Construction Procedures
(d)    Preparation of bearing seat; and                    Construction procedures which are required to be
                                                           submitted by the Contractor to the Superintendent in
(e)    Installation of bearing.
                                                           accordance with Clause 5 of MRS11.50 Specific
Item 8222  Pot-type bearings,          [rated load         Quality System Requirements are listed in Table 3.
           capacity], [fixed / sliding]
Work Operations incorporated in the above item
include —
  Page 75.2 of 6
  MRS11.75
  12/99
Department of Main Roads                                                                             MRS11.75
Standard Specification                                Supply and Erection of Prestressed Concrete Girders

Table 2 - Hold Points, Witness Points and Milestones

       Clause                    Hold Point                   Witness Point                   Milestone
         5.4.1          1 Approval of handling,                                        Submit handling,
                          transport and storage of                                     transport and storage
                          girders                                                      procedure (14 days)
            7.1         2 Approval of erection            Erection of girders          Submit erection
                                                                                       procedure (21 days)
         7.2.3          3 Installation of bearings

Table 3 - Construction Procedures                           5.3.3     Acceptance of the Girders by the
                                                                      Contractor
    Clause                  Procedure
                                                            The Contractor shall check the girders for quantity
      5.4.1       Handling transport and storage of         and condition upon taking delivery and shall
                  girders                                   immediately report to the Superintendent any defect
      7.1         Erection of girders                       or deficiency Nonconformance .

                                                            5.3.4     Damage to Girders
5             PRESTRESSED CONCRETE                          In the event of a girder sustaining damage after the
              GIRDERS                                       girder has been accepted by the Contractor, such as
                                                            cracking and spalling or deformation of projecting
5.1           Supply of Girders                             reinforcement or bolts or damage to cast-in sockets
Where listed in the Principal Supplied Materials List       and formwork cones, the girder shall be set aside
(Form C6827), prestressed concrete girders will be          until it has been inspected by the Superintendent
supplied by the Principal. Where not so listed,              Nonconformance . The cost of repairs to damaged
prestressed concrete girders shall be supplied by the       girders and the cost of replacing rejected girders
Contractor.                                                 shall be borne by the Contractor.

5.2           Manufacture of Prestressed                    5.4       Handling, Transport and Storage
              Concrete Girders                              5.4.1     General
Prestressed concrete girders shall be of the lengths        Girders shall at all times during handling, transport
and dimensions shown on the Drawings and shall be           and storage, be kept in such a position that the lifting
manufactured in accordance with the requirements            loops are uppermost and the girder is vertical.
of MRS11.73 Manufacture of Prestressed Concrete
Members and Stressing Bars.                                 The method of handling, transport and storage shall
                                                            be such as to avoid the danger of fracture by impact,
5.3           Girders Supplied by the Principal             undue bending, twisting and whipping. Girders shall
                                                            be moved only while fully suspended. In no case
5.3.1         Supply Location                               shall they be moved by dragging across the terrain.
Girders supplied by the Principal will be made              The Contractor shall submit its procedure for the
available at the point of delivery and by the transport     handling, transport and storage of girders not less
mode shown in the Principal Supplied Materials List         than 14 days prior to commencement of any such
(Form C6827).                                               activities Milestone .
5.3.2         Time of Delivery                              Handling, transport and/or storage of girders shall
                                                            not proceed until the procedure has been approved
The time of delivery will generally conform to the          by the Superintendent Hold Point 1 .
construction program supplied by the Contractor
with its tender.                                            5.4.2     Lifting
Should on-site construction be delayed, the                 Prestressed concrete girders are provided with in-built
Contractor may be required to accept delivery of the        lifting devices. Girders shall be lifted only by these
girders at any time after the programmed date and to        lifting devices and no other means of lifting shall be
store the girders at no expense to the Principal.           used at any stage during handling unless prior written
                                                            approval has been given by the Superintendent.


                                                                                                       Page 75.3 of 6
                                                                                                          MRS11.75
                                                                                                               12/99
MRS11.75                                                                         Department of Main Roads
Supply and Erection of Prestressed Concrete Girders                                 Standard Specification

Cranes shall work within their rated capacity. If         ground beneath the girders shall be levelled so as to
requested by the Superintendent, the Contractor shall     maintain the same clearance as at the supports. Girders
make available for inspection the crane                   shall be independently braced laterally to prevent
manufacturer’s load chart for the crane which is          overturning.
proposed for handling and/or erection with details of
counterweight, jib length and rigging.
                                                          6         MATERIALS
5.4.3        Transport                                    6.1       Cement Mortar
5.4.3.1            General                                6.2       Cement
The Contractor shall assess the route from the place      Cement shall be Type GP or Type HE complying
of manufacture to the Site and, in its submission to      with the requirements of AS 3972.
the Superintendent in accordance with Clause 5.4.1,
shall include full details of the transport               6.3       Sand
arrangements, including means of limiting torsional
forces on the units during transport to prevent           Sand shall consist of sharp, coarse, clean siliceous
                                                          sand, free from dust, clay, organic matter or other
torsional cracking. The Contractor shall also supply
                                                          deleterious substances. Grading and fineness shall
details of anticipated arrival time of the girders on     be such that the mortar produced shall be impervious
the Site and the planned rate of delivery.                to moisture.
Girders shall be transported only after all inspections
required by the Superintendent have been                  6.4       Water
satisfactorily completed.
                                                          Water shall be free from matter injurious to
                                                          concrete, mortar and embedded items.
5.4.3.2            Certification of Vehicles
Prime movers shall display a current Certificate of       6.5       Proportions
Inspection issued by the Queensland Department of         Mortar shall consist of a mixture of 1 part of cement
Transport.                                                to 3 parts of sand uniformly mixed so that no
Prime movers and trailing equipment shall display a       segregation occurs.
current Licence to Hire issued by the Queensland          The water/cement ratio shall be the minimum
Department of Transport.                                  required, to allow placement as specified for the
                                                          particular application.
5.4.3.3            Mass of Loads
All road transport shall comply with the vehicle          6.6       Epoxy Putty
limits prescribed by the Transport Operations (Road       Epoxy putty shall consist of a proprietary two-part
Use Management) Act and Regulations 1995.                 epoxy product capable of gap filling between the
                                                          restraint angle and the headstock, and between the
5.4.3.4            Escorts and Pilots                     bearing and the girder soffit.
All road transport shall comply with the relevant         A certificate from the manufacturer shall be
clauses of the Traffic Regulations pertaining to          provided to verify the suitability of the product for
provision of pilot vehicles and/or police escorts.        the intended purpose.

5.4.3.5            Support of Girders During              6.7       Bearings
                   Transport
                                                          Laminated elastomeric bearings and pot-type
During transport, concrete girders shall be supported     bearings shall comply with the requirements of
at their ends on bearers placed vertically under the      MRS11.81 Bridge Bearings.
lifting devices and they shall be braced against
overturning and lateral whipping.                         6.8       Girder Restraint Angles
                                                          Girder restraint angles shall be fabricated to the
5.4.4        Support of Girders During Storage            details shown on the Drawings.
Girders shall be stored on timber support bearers         Fabrication shall be in accordance with the
positioned one at each end vertically under the lifting   requirements specified in MRS 11.78 Fabrication of
devices. The contact surface between girders and          Structural Steelwork.
bearers shall have a minimum plan area of 0.1 m2. The
bearers shall be sufficiently high to store the girders   Girder restraint angles shall be hot-dipped galvanised
clear of the ground even if subsidence occurs. The        after fabrication in accordance with AS 4680.
  Page 75.4 of 6
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  12/99
Department of Main Roads                                                                               MRS11.75
Standard Specification                                  Supply and Erection of Prestressed Concrete Girders

6.9       Girder Restraint Fasteners                         bearing shall not be installed until approved by the
                                                             Superintendent Hold Point 3 .
Girder restraint to girder fastening bolts, nuts and
washers shall be supplied and fabricated as shown            The PTFE surface shall be coated with an approved
on the Drawings and hot-dipped galvanised in                 release agent prior to installation of the bearing.
accordance with AS 1214.
                                                             Sliding bearings shall be set central to the range of
                                                             movement.
7         ERECTION OF PRESTRESSED
          CONCRETE GIRDERS                                   Sockets for holding down bolts shall be installed in
                                                             the bearing pedestal as shown on the Drawings to a
7.1       General                                            tolerance of ± 2 mm of the dimensions relative to the
                                                             bearing pedestal.
The Contractor shall submit its procedure for the
erection of girders not less than 21 days prior to           Pot-type bearings shall be seated on epoxy putty or
commencement of such erection Milestone .                    cement mortar as shown on the Drawings.
For a structure incorporating T girders, the Contractor      Where the bearings are seated on cement mortar,
may be required to submit to the Superintendent, a           wedges shall be used to temporarily support the
certificate, signed by a Registered Professional             bearings at the correct level. Wedges shall be
Engineer of Queensland, verifying that the Contractor’s      removed when the mortar has cured and the
proposed construction methods will not compromise            remaining voids shall be filled with cement mortar.
the structural adequacy or the long term durability of
the completed structure. The Superintendent may              Surplus epoxy putty or cement mortar squeezed out
request such a certificate up to 7 days after the receipt    during placement of bearings shall be removed
by the Superintendent of the Contractor’s erection           immediately before it has set.
procedure. The certificate will be considered to be part
of the Contractor’s erection procedure.                      7.3       Installation of Prestressed
                                                                       Concrete Girders
Erection of girders shall not proceed until the
erection procedure has been approved by the                  7.3.1     General
Superintendent Hold Point 2 .                                Unless shown otherwise, prestressed concrete
Erection of girders shall be a Witness Point                 girders shall not be seated at any position other than
Witness Point .                                              at the bearing points.

The Superintendent shall have the right at all times         All holding down bolts and cored holes shall be
to stop any handling deemed injurious to the girders.        carefully aligned during placing of prestressed
                                                             concrete girders.
Girders shall not be placed on reinforced concrete
headstocks until the concrete in the headstock and           7.3.2     Seating Girders on Laminated
bearing pedestals has attained a compressive                           Elastomeric Bearings
strength of 70% of the characteristic strength.
                                                             Where the Drawings show that the prestressed
7.2       Installation of Bearings                           concrete girder is to be seated on a laminated
                                                             elastomeric bearing, the top surface of the bearing
7.2.1     Preparation of Bearing Seat                        shall be coated with epoxy putty.
The bearing seat shall be thoroughly cleaned prior to        The prestressed concrete girder shall be placed on the
installation of the bearing. If a curing compound has        bearing and the periphery of the bearing checked to
been applied to the bearing seat, it shall be removed        ensure that the entire interface between the prestressed
by grinding or sandblasting then cleaned of dust and         concrete girder and bearing is filled with putty. Surplus
laitance with clean water.                                   putty squeezed out shall be removed before it has set.

7.2.2     Installation of Laminated                          If the putty sets before completion of this operation,
          Elastomeric Bearings                               the girder shall be lifted and all contact surfaces
                                                             cleaned before repeating the process.
Elastomeric bearings shall be placed within ± 3 mm
of the correct plan position on the bearing seat.            7.3.3     Seating on Pot-Type Bearings

7.2.3     Installation of Pot-Type Bearings                  The prestressed concrete girder shall be placed
                                                             squarely on the bearing and the attaching bolts
Prior to installation, pot-type bearings, including          inserted. Bolts shall not be tightened until both ends
sliding surfaces, where applicable, shall be inspected       of the prestressed concrete girder have been placed
and, notwithstanding any previous approval, the              in their correct positions of their respective bearings.
                                                                                                         Page 75.5 of 6
                                                                                                            MRS11.75
                                                                                                                 12/99
MRS11.75                                                    Department of Main Roads
Supply and Erection of Prestressed Concrete Girders            Standard Specification

7.3.4          Fixed End Restraints
The fixed ends of prestressed concrete girders shall
be lowered slightly ahead of the expansion end to
ensure that the holes in the girders align with the
corresponding holes in the girder restraints.
The nuts and washers shall be assembled on the girder
restraint holding-down bolts, and the girder restraint to
girder fastener bolts, nuts and washers shall be
installed. All nuts shall be securely tightened before
removing the load on the lifting gear.

7.3.5          Temporary Bracing
When no restraint angles are shown on the
Drawings, before fully removing the load from the
lifting gear, prestressed concrete girders shall be
braced independently so that they cannot be
overturned accidentally.

8              LOADING OF T GIRDERS
Constructional Plant or vehicles of any type shall not
be placed on the surface of T girders prior to casting
the concrete deck.

9              CAST IN SITU DECK
A cast in situ reinforced concrete deck shall be
constructed in accordance with the requirements of
MRS11.77 Bridge Deck.




    Page 75.6 of 6
    MRS11.75
    12/99

								
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