Response to an American engineer's query

[G Vishwanath]

List,   I received the following friendly mail and inquiry from a fellow member of the seaint list.   I am reproducing his questions and my answer in the belief that it will be of  interest to others too. Regards Vish ===========  Vish, Now I think of some other questions.  I hope you know you’re dealing with one of those parochial Americans that doesn’t know too much of what’s outside the US. Do you not use the metric system in India?  Do you use steel sections available here in the US, the ones listed in the AISC manual?  Are the model steel codes based on the AISC specifications?  Do you use the ASD specification, or are you required to use the LRFD spec.  Are the building codes modeled on British or US IBC codes? Regards, **** ******* ======================= Dear Parochial American,   Here are the answers.   This problem was not referred to me from an Indian customer. The query came from an American Customer who knows I am a qualified structural engineer though I last did serious design over 15 years ago and am now totally involved in running a detailing set up catering exclusivlely to US fabricators.   Yes, we use the metric system in India for local jobs. But when I work on US detailing we have to use imperial units. We are now truly "ambidexterous" and switch from Imperial to Metric and vice versa quite naturally and without any strain. It took some time to get used to this constant switching.   In India ,we gave up Imperial units sometime in 1955 after getting the British out of our country. We became Independent in 1947   No, we don't use steel sections listed in the Aisc manual for local jobs. We use locally rolled sections. We have very very very limited variety Just 7 sections to choose for beams. Makes it simple. I knew all the properties by heart and never needed to look up a table or manual The available sections  range from 4" in depth to 24" in depth. The flanges are narrow, not like your W sections. The properties are not at all attractive, compared to the weight. They are close to your S sections.   But no one minds. We use steel in very limited quantities. Almost all construction uses reinforced concrete. Steel is used only by the Railways and in heavy industrial structures.   When we need sections above 24" in depth, we fabricate them from plates. Welding is cheap in India. No one minds the extra labour. We also use extensive field welding. The bolts are only for erection and most often they dont match up at site but that's not important. We just somehow keep them in position and weld it. The skills of the erection crews here are amazing. Without cranes and other sophisticated equipment that you use, they do an amazing job, though they take more time.     We use ASD only, not LRFD for steel design. For the past 25 years, the Bureau of Indian standards has been trying to finalize the Draft code for LRFD design but no one seems to be interested in expediting this. Everyone is comfortable with ASD and none of us are waiting with bated breath for the LRFD code.   The first draft code for steel structures (IS:800 - came out in 1956 and it was an exact copy of the British code (that we used till then)  except that the units were changed from Imperial to Metric. Later there was revision in 1962 and one more in 1984.   The next one has been coming out "any time now" for the past 23 years! To the best of my knowledge it is still not out. I have with me a copy of the  draft that is still being debated and discussed and this draft is nearly 15 years old.  I stopped following up what is happening on this front every since I gave up design and switched to detailing. In case there has been an update I would like to know.     We use Steel that conforms to A36 mostly. Only in heavy industrial buildings do we use steel equivalent to your 50Ksi steel and that too only for plates.   While labor is cheap and plentiful, Raw Steel is VERY Costly here in India. People here grudge paying even for A36 steel. Catch thyem spending on A572 or A992? Who needs it? Hardly anyone.   Concrete/Cement/reinforcement bars are available in plenty and are the material of choice for most of our construction.   I trust you now know a little more about us and have become less parochial!   Regards Vish PS: I am posting this to the group (after editing out your name)  as others too may be interested in your question and my answer.

[Harold Sprague]

Vish,
Thanks.  This is interesting.  We do work all over the world and indigenous design and construction practices are of interest to me.  It has been my experience in many countries a lot of heavy industrial steel structures are constructed of plate shapes that are welded to form a similar shape that generally conforms to US, British or Japanese shapes. 
 
Is that practice used in India?

Regards, Harold Sprague


 

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Date: Sun, 22 Nov 2009 22:17:37 -0800
From: gvsh...@yahoo.com
Subject: Response to an American engineer's query
To: sea...@seaint.org; steel-...@yahoogroups.com; misciro...@yahoogroups.com

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