Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

FEMA Tier3 Analysis - Seismic Factor

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Hello:
 
I wanted a clarification on one of the issue mentioned in FEMA 310 which is currently the ASCE standard 31-03. 
 
Referring to sec5.2.1, it states that 75% of the calculated seismic force can be used for a Tier 3 analysis. 
Q1. Is this only for the evaluation or the retrofit design which follows?
 
It suggests that FEMA 356 be used for this evaluation.  It says that the 75% force is taken since the documents (FEMA356) are intended for design. 
 
Q2. What force level should be considered when upgrading the structure - 100%?
 
Suppose during evaluation, a few beams (say 10) do not meet the suggested criteria and were found 20% overstressed under the 75% seismic force level.  But while using 100% seismic level for the retrofit, several more members might fail?  How do you justify this unless you did a 100% analysis during the evaluation and reported the cost to the client.
 
-  Aswin
_________________________________
Aswin Rangaswamy, P.E.
Jacobs Facilities Inc. (www.jacobs.com )
(714) 503-3772 (P); (714) 503-3865 (F)