Regarding ductility criteria

03-Analytical/modelling capabilities
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mangesh shendkar
Posts: 25
Joined: 02 Dec 2016, 19:31

Regarding ductility criteria

Post by mangesh shendkar »

Hello, I have done pushover analysis of RC infilled frame so , I have to calculate the ductility of RC infilled frame . Is there any difference in method for calculation of ductility for bare & infilled frame??? and generally which method should I used ?? if anybody help me it will be very beneficial for me as well as our institution..
Thanks
huffte
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Re: Regarding ductility criteria

Post by huffte »

There are various measures of ductility - curvature ductility, displacement ductility. You likely intend to calculate the displacement ductility, which is equal to the maximum displacement divided by the yield displacement. So you simply need to use some engineering judgment to establish the yield displacement. The maximum displacement is easily obtained form SeismoStruct. The best reference for such computations is the book by Priestley, Calvi, and Kowalsky - Direct Displacement Based Seismic Design of Structures, pages 12-14 (ISBN: 88-6198-000-6). You may also be able to find assistance using a web search on 'yield displacement seismic design'. Basically, a line is drawn from the origin to the point on the pushover curve at first yield of reinforcing. This line is extended to the nominal capacity line to establish a yield displacement from the pushover curve. The maximum displacement is taken as the lesser of the peak displacement and the displacement at which a strength drop of 20% occurs. These are really not SeismoSoft specific questions, mangesh shendkar, but I hope the above will get you going in the right direction and I encourage you to consult the textbook referenced and online materials. Best of luck.
Tim Huff
mangesh shendkar
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Joined: 02 Dec 2016, 19:31

Re: Regarding ductility criteria

Post by mangesh shendkar »

thank you so much sir. and other question is that ductility for infilled rc frame we can calculate by the method like we use for rc bare frame...
huffte
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Re: Regarding ductility criteria

Post by huffte »

Displacement ductility is the maximum displacement divided by the yield displacement, regardless of structure type. Both values require some engineering judgment when detailed finite element analysis (as opposed to bi-linear idealizations, in which case engineering judgment is still required, but on the front end instead of after the analysis) is used.
Tim Huff
mangesh shendkar
Posts: 25
Joined: 02 Dec 2016, 19:31

Re: Regarding ductility criteria

Post by mangesh shendkar »

thank you so much sir...
mangesh shendkar
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Joined: 02 Dec 2016, 19:31

Re: Regarding ductility criteria

Post by mangesh shendkar »

I have to calculate response reduction factor from pushover analysis of RC infilled frame so how can I calculate it??? give me some suggestions please
THANKS
huffte
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Joined: 22 Jul 2011, 10:19
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Re: Regarding ductility criteria

Post by huffte »

The force reduction factor is the ratio of the force which would have been experienced had the structure remained elastic divided by the force experienced by the inelastic structure. So, for an approximation, you could extend the initial, linear portion of the pushover curve to the desired level of displacement and read the corresponding inelastic displacement from the pushover curve. Then, divide the two values of force.
Tim Huff
mangesh shendkar
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Joined: 02 Dec 2016, 19:31

Re: Regarding ductility criteria

Post by mangesh shendkar »

Actually sir i calculated the stiffness , strength , ductility etc.from pushover curve but now I am confused while calculating R factor so can u explain in details?? IF it is possible then it will be too much beneficial for my project.
THANKS
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seismosoft
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Re: Regarding ductility criteria

Post by seismosoft »

Mangesh,
You need to refer to the relevant Regulations and literature for this. For example, have a look at the ASCE 41-13 regulations, eq. (7-31).
Unfortunately, this is a forum for the use of Seismosoft's application, it is not a general forum for earthquake engineering.
Issues such as the calculation of the R-factor should be better discussed with your supervisor.

Seismosoft Support
mangesh shendkar
Posts: 25
Joined: 02 Dec 2016, 19:31

Re: Regarding ductility criteria

Post by mangesh shendkar »

OK
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