Direct Generation of Seismic Floor Response Spectra for Classically and Nonclassically Damped Structures

摘要

Floor response spectra are commonly used as seismic inputs for the design of secondary systems. Here several direct approaches based on the method of mode displacement as well as mode acceleration have been developed for generation of floor spectra for classically and non-classically damped systems. The mode displacement approaches require pseudo acceleration and relative velocity spectra whereas the mode acceleration approaches require relative acceleration and velocity spectra as their seismic inputs. These proposed approaches have been validated by a comprehensive numerical simulation study involving several ensembles of time histories. For structural systems with dominant high frequency modes, the mode displacement approaches may give inaccurate results if only a first few modes are used in the analysis, whereas the mode acceleration approaches will still predict the response accurately. Therefore, the mode acceleration approaches are proposed as better alternatives to the mode displacement approaches which are currently used.