Hi!
I am working on FEMA 440 Procedure C for pushover analysis. If you check point C12 on page 6-8 it says: "Increase or decrease the assumed performance point and repeat the process to generate a series of possible performance points". Does it mean we have to repeat from step 6? I ask because as we change the assumed performance point, the alpha stiffness changes as well. Potentially it can change from positive to negative, in which case are we supposed to change the assumed hysteretic system from say bilinear hysteretic to strength degrading? This causes weird jumps in locus of performance points. Are we also supposed to change coefficients A-L when calculating the effective damping and effective period?
When I draw locus of performance points using hand calculations and SAP2000 results, I get slight deviations. This is mainly when alpha value changes between 0/2/5/10/20 ranges, I get a feeling SAP2000 only calculate the coefficients A-L once using equal displacement rule and reuse them for other trial performance points.
Thanks
I am working on FEMA 440 Procedure C for pushover analysis. If you check point C12 on page 6-8 it says: "Increase or decrease the assumed performance point and repeat the process to generate a series of possible performance points". Does it mean we have to repeat from step 6? I ask because as we change the assumed performance point, the alpha stiffness changes as well. Potentially it can change from positive to negative, in which case are we supposed to change the assumed hysteretic system from say bilinear hysteretic to strength degrading? This causes weird jumps in locus of performance points. Are we also supposed to change coefficients A-L when calculating the effective damping and effective period?
When I draw locus of performance points using hand calculations and SAP2000 results, I get slight deviations. This is mainly when alpha value changes between 0/2/5/10/20 ranges, I get a feeling SAP2000 only calculate the coefficients A-L once using equal displacement rule and reuse them for other trial performance points.
Thanks
