STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

perwez at lntecc.com · Guest

Dear Mr. Sukanta
Please see an excerpt from an article of Dr. SK Jain in ICJ - November
2003.

In Clause 7.8.2.1, the code specifies damping to be used for steel
buildings as 2 percent of critical, and for RC buildings as 5 percent of
critical. This leads to a steel building being designed for about 40
percent higher seismic force than a similar RC building. While it is
true that in a RC building the damping may be higher due to development
of micro cracks in concrete; however, steel buildings have inherent
advantages of better seismic performance. Moreover, both an RC building
and a steel building may have the same types
of partitions and other non-structural elements which will contribute
same material damping. Hence, it cannot be justified that steel
buildings should be designed for 40 percent higher design forces than
similar RC buildings. Clearly, specification of damping has a direct
bearing on the seismic design force level and considering this, it is
recommended that the code should require both steel and RC buildings to
be designed for 5 percent damping.

Kind Regards
Perwez Ahmad
==========================
Perwez Ahmad
Senior Design Engineer
L&T ECC Division
山Poonamallee路
Manapakkam, PB No. 979
Chennai-89
Mobile: +91-9840619804
Office: +91-44-22528486
perwez[AT]gma...
ahmad_perwez[AT]yah...
===========================

-----Original Message-----
Message From sukanta.adhikari[AT]gma... [mailto:sukanta.adhikari[AT]gma...]
Sent: Wednesday, December 06, 2006 8:49 PM
To: Perwez Ahmad
Subject: seismic

Dear sefians,

I want to know why does a steel structure experiences 40% more seismic
forces compared to R.C.C structure.

Regards,
S.Adhikari

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