A Critical Look at the Use of Design Spectrum Shape for Seismic Risk Assessment

The effects of using design spectrum shape over actual response spectra on earthquake damage estimates has been investigated. A series of numerical simulations were conducted to estimate the expected damage. The simulations were conducted with four different spectral shapes, two different ground-motion prediction equations (GMPEs) and three different soil classes. As a result of the numerical simulations, it was observed that the use of design spectrum shape leads to over- or underestimation of damage estimates relative to those obtained from the actual spectrum computed using GMPE. The damage estimates were observed to be sensitive to the selected design spectrum shape, the GMPE used to compute the spectral values, the soil type, and the fundamental period of the building typology. It was also observed that Eurocode- and IBC-type design spectrum shapes led to significantly different damage estimates compared to one another.