Analysis does not stop even when collapse mechanism forms

04-Unexpected behaviour/errors
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emreakin
Posts: 15
Joined: 08 Aug 2017, 13:55

Analysis does not stop even when collapse mechanism forms

Post by emreakin »

I am performing nonlinear time history analyses of two different types of reinforced concrete frame buildings. One is ductile and designed according to the seismic design principles. The other one is nonductile and have certain deficiencies in terms of seismic response. I also use "number of story" as a variable. I have 3, 5 and 8 stories buildings which are designed as either ductile or nonductile. I apply Kocaeli Yarımca EQ motion (no scaling) and use lumped masses. The number of integration sections for the columns is 5 and number of section fibers is 100. As a result, I checked ultime inter-story drift ratio (IDR) at all story levels. And I saw that the ultimate IDR for the first floor may go up to 5%-6% for the ductile and 9%-12% for the nonductile building models. It was interesting to observe such high IDR values. Then I checked stress/strain values at the firsty story column ends for one building model. And what I saw was that all first story column reinforcements (at the top and bottom) has already yielded and plastic hinges formed long before these IDR values were reached. It is very interesting because collapse mechanism should have taken place before I saw these IDR values. It looks like Seismostruct does not stop the analysis when mechanism (plastic hinge formations at both ends of all first story columns) take place. Do I have to make any arrangement in analysis setup? Or is there anything that I am missing?
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seismosoft
Posts: 930
Joined: 06 Jul 2007, 04:55

Re: Analysis does not stop even when collapse mechanism form

Post by seismosoft »

The question was answered at the following post:
http://seismosoft.com/forum/viewtopic.php?f=4&t=4158

Please try not to post the same question more than once.
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