Inelastic seismic demand spectrum with A_y-D_y format and its application in performance based seismic design

Inelastic seismic demand spectrum with yield spectral acceleration-yield displacements format is introduced to the improved capacity spectrum method in order to consider multiple performance objectives in displacement based seismic design,because it has the advantage of that structural periods represented by radial lines intersecting demand spectra with different ductility factors are all the same.The multiple performance objectives are usually expressed as that designed structures can resist against minor earthquake without any damage,resist against moderate earthquake with repairable structural damage and resist against strong earthquake without collapse.Seismic performance evaluations of a RC frame using pushover analysis and capacity spectrum method under different earthquake design levels are illustrated as an example.