Probably you are using Response reduction factor 'R' much greater than 1.0. The response reduction factor that is a combination of the ductility factor, redundancy factor and overstrength should be automatically accounted for in the pushover analysis (capacity curve). Therefore, you should set R=1 while defining the demand curve (or demand spectrum). The capacity spectrum already should include all the influences for R-factor.

Hi dear Azeel Pk

You need to assign 0.5*I/R*g for DBE evaluations and I/R*g for MCE evaluations.

Akanshu Sharma

I used R=1 and scale factor =2*g (MCE) while defining inbuilt demand spectrum of IS 1893 2016. but still my performance point is coming on elastic range (capacvity is higher than demand). What should i do then??

If your capacity curve is correctly determined then your structure is too strong and it remains linear elastic range under MCE. Perhaps you can share a picture of your results to understand it better.

Akanshu Sharma I am using IS 1893 2016(inbuilt) response spectra for defining demand spectra taking R=1 and SF=2*g=19.62 (MCE). While doing push over analysis using FEMA 440 equiavalent linearisation method the performance point lies in the elastic range(demand is low as compared to capacity). I used ISMB 450 and ISMB 500 for beams (as per UPBD) and rectangular hollow columns. The elastic design result is also attached along with the pushover curves and demand spectrum function.

Azeel Pk , probably your structure is too strong. Try using smaller member sizes and see whether your procedure otherwise is fine or not.

As u can see from the image attached, i used the minimum column sizes and demand capacity ratio of all columns is on the range of 0.9. If i reduce the size of columns for reducing the structure capacity, the demand capacity ratio exceeds 1 and it is not preferable.

Sir I am using auto hinge as per ASCE 41-17 for the beams and the details is also attached here.. Is it okey?? Or i need to define hinges manually? Akanshu Sharma

While calculating the demand-capacity ratio, what are you considering as the response reduction factor R?

The whole idea of pushover analysis is that some structural elements should yield in order to allow the re-distribution of the forces and utilizing the ductility to ensure the safety against collapse. If you would not allow any structural members to yield, your structure will remain in the elastic range, as you are getting in your results.

by applying hinges to the structural members we are allowing them to yeild right?

could you please explain the first first part of your answer. Is it rergarding design part or pushover analysis part? Akanshu Sharma