www.sefindia.org

[macesundar at yahoo.com]

Dear Friends,

I was involved in a project 2 years back where the client requested a Pre-Engineered Steel Building in compliance with IS. PEB uses built-up main structural sections (mostly portal frames) and cold-formed secondary members.

Most of the foreign Companies we contacted gave us attractive prices for US based ASCI codes and MBMA guidelines. However, they stated that the steel quantity increases enormously if IS was followed and increased the price 1.5 to 2 times the original quotes!! Is our code so conservative?

There were also a few issues which were never resolved such as -

1. Automated fabrication finds welding on only one side of the I section more economical & experiments have proven these to be effective. IS 800 is silent on the fabrication detail, even if some illustrations indicate the flange welded to both sides of the web!

2. Buckling behaviour (both local & overall buckling) of non-prismatic members (which are the norm in PEB) are not detailed in IS 800. What factors are to be used?

3. Most of the PEB systems rely on experimental values determined & published by MBMA for the entire system behaviour (including diaphragm action of the wall / roof cladding) and safety factors / coefficients used accordingly. This results in substantial savings in material & cost. This is part of the pioneering work done by an eminent Engineer of Indian origin in the US. Can these results be used as a basis to design systems which deviate from IS 800?

Regards,
Sundar



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