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NEW BUILDING CONSTRUCTION METHODS PRE ENGINEERED STEEL BUILDINGS PEB (DOC)

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NEW BUILDING CONSTRUCTION METHODS PRE ENGINEERED STEEL BUILDINGS PEB (DOC) Powered By Docstoc
					By Francis Gichuhi KamauWe are increasingly seeing the effects of
building collapse due to earthquakes in regions such as Haiti and
collapse due to poor workmanship such as the recent building collapses in
Kiambu. With rapid urbanization, more high-rise buildings are coming up
in major towns creating perfect recipes for disaster as people get
trapped underneath tons and tons of concrete incase the building
unfortunately collapses -either due to an earthquake or poor workmanship.
There are solutions to avoid this kind of disaster by having flexible
steel grid supported buildings with light-weight sandwich panel wall
infill. Several major towns in Kenya such as Nakuru sit right in the
middle of the Rift Valley which is a seismically unstable region and
earthquakes are not known to give notice before they strike.Measures
should be taken to ensure that there are mechanisms in place to give
early warning to avoid disasters.Countries that are prone to earthquakes
such as Japan have an average of 40% of new high-rise buildings coming up
in Steel structural frames-one of the world's highest-this is partly dues
to steel's ability to resist the impact of severe earthquakes. Past
earthquakes in USA [San Francisco-1906, Long Beach-1933, and Japan [Kanto
-1923] during the first part of this century gave engineers confidence in
steel as a reliable material for earthquake resistant design. During
these events, there were typically fewer problems observed in steel
structures as compared with concrete and masonry buildings of similar
size and scale. PEB system of construction is based on the U.S.A Building
code. PEB system originated from U.S.A which produces over 1 million PEB
Structures per year.In Kenya, we mainly rely on the British Building code
and standards for construction. The British Standard is mainly Reinforced
-Concrete based as in most structures such as columns and beams are
designed to be concrete-based with twisted steel reinforcement of between
8 mm to 20mm thickness in the inside. This is the type of building
construction that you will see every day in Kenya and East Africa in
general.The PEB system replaces the concrete columns and beams with I
Section steel beams and columns. With the rapidly increasing price of
cement for making the concrete, this design is certainly more cost-
effective.The floor surface can be made of concrete or
steel.International Casino Car Park, Chiromo road roundabout. A good
example of this in Kenya is the Car Pak at the International Casino hotel
next to the Chiromo road roundabout near Westlands.This car park has a
concrete surface suspended and supported by steel I beams and columns as
shown below.The car park is very strong-it has supported the weight of
cars for very man years and it has not a slight sign of failure.This
means that if used to support a building where the loading is mainly
human and furniture e.g. offices and residential buildings, the PEB
system will work excellently since if it can support the heavy load of
cars, then it can support the light load of humans and
furniture.Earthquake Loading design.The structural design of the PEB will
depend on the Live loads, Earthquake, collateral and wind loads that are
specified by the consultant structural engineer in conjunction with the
relevant Local Authority Building approval department.PEB subsystemsThe
main building structure comprises of 2 subsystems:-[1]a rigid steel
frame including columns,rafters,beams and purlins and [2] wall and roof
panels.The roof and walls are made of Sandwich panels. Sandwich panels
comprise of an exterior metal skin, a polyurethane interior core and an
interior flat skin made of metal. The core thickness is available in 35,
50, 75 and 100mm.The density of the polyurethane is 35-40Kg/m3.Design
Code.The design code used is in accordance with the Steel Construction
Manual published by the American Institute of Steel Construction
[AISC].All welding is done in accordance with the Structural Welding
Code-Steel D1.1 of the American Welding Society[AWS].PEBs are designed
using guidelines published by Metal Building Manufacturers Association of
U.S.A which is a world-recognized authority on pre-engineered steel
buildings and its guidelines are accepted as standard practice in his
industry.The Universally recognized code is the International Building
Code published by the International Code Council of U.S.A.In Kenya,
recently, a commission was formed under he Ministry of Hosing to review
the country's Building Code which was published in 1963 and is out-dated.
This code is based on the British Building code and hence effectively
discourages other cost-effective methods of construction such as PEB in
Kenya. Once the new Building Code is published, we hope that it will
include other innovative building construction methods found all over the
world especially now that we have seen a few buildings collapsing around
Kenya.Available SuppliersMore technical details and cost estimates can be
obtained by contacting Mr. Anis Gafoor of Mabani Steel -Tanzania [+255
688 025125] which is an U.A.E company with a branch in Tanzania.
www.mabanisteel.com. Mr. Gafoor was recently in Nairobi in the week of
January 17th 2010 to January 23rd 2010.Frank
Gichuhi.Architect.www.a4architect.com


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