hello,
I am doing Pushover analysis of a G+15 Storied building by ETABS Software. I want to check the structural ductility according to FEMA 440 and level of structural performance according to ATC-40 of this building. I would very grateful if anyone share calculation process by using ETABS software Results.
hi Md. Sohidul Islam
Here are the steps to check structural ductility and performance level according to FEMA 440 and ATC-40 using ETABs results for a G+15 building pushover analysis:
Run pushover analysis in ETABS up to the target displacement. Make sure to record base shear and roof displacement at each analysis step.
Plot the pushover curve of base shear vs roof displacement. From this curve, determine the yield and ultimate displacement (Δy and Δu).
Calculate ductility factor μ as Δu/Δy.
Check ductility requirements for seismic force-resisting systems according to FEMA 440 Table C2-3. Requirement is ductility factor μ ≥ 2 for Special Moment Frames.
Determine performance point as the intersection of demand curve with design spectrum. Note the spectral displacement SD1 and acceleration SA1.
Calculate post-yield stiffness degradation index Iγ using equation from FEMA 440.
Plot Iγ vs ductility factor μ on ATC-40 Figure 6.2-1 graph. Read off the expected performance level.
Cross check performance level does not exceed the Collapse Prevention (CP) level for Life Safety objective as per ATC-40 Section 6.4.1.
Tabulate results including pushover curves, μ, Iγ values and determined performance level for reporting.
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