Document Sample
					By Francis Gichuhi Kamau

We 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 subsystems

The 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 Suppliers

More 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. Mr. Gafoor was recently in Nairobi
in the week of January 17th 2010 to January 23rd 2010.

Frank Gichuhi.


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