What is Response Spectrum Analysis?
Response spectrum analysis (RSA) is a procedure for computing the statistical maximum response of a structure to a base excitation (or earthquake). Each of the vibration modes that are considered may be assumed to respond independently as a single-degree-of-freedom system. Design codes specify response spectra which determine the base acceleration applied to each mode according to its period (the number of seconds required for a cycle of vibration). The diagram below shows the Basic Seismic Hazard Acceleration Coefficient specified in NZS 4203 for deep soil sites (the most severe site category). Each curve represents a different ductility factor. The design response spectrum is obtained by multiplying these curves by a structural performance factor, a risk factor, a zone factor, and limit state factor. Other earthquake loading codes have similar provisions. Click here if you want to download a Microsoft Excel spreadsheet file containing Australian and New Zealand design code response s
