Rigid-Plastic Pseudo-Spectra: Peak Response Charts for Seismic Design

PORCU, MARIA CRISTINA;M. MASCIA

2006-01-01

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Abstract

Seismic design generally involves the assessment of the maximum plastic displacement of elastoplastic structures under given earthquakes. Recent studies show that this displacement can be evaluated by referring to a simple rigid-plastic model. This can be done with the help of an appropriate rigid-plastic response chart, called here pseudo-spectrum. For a given earthquake it plots the peak displacement of a rigid-plastic oscillator as a function of its acceleration at the yield limit. Despite their simplicity, rigid-plastic pseudo-spectra have not been studied extensively. The present paper discusses the main features of such spectra and presents the rigid-plastic pseudo-spectra relevant to some 38 earthquakes of the last 50 years. These spectra show that the methods currently available to estimate the seismic response of a rigid-plastic oscillator may fail to give accurate results. To facilitate comparison between different earthquakes, the rigid-plastic pseudo-spectra are also presented in a non-dimensional form. The latter may come in handy when constructing conventional rigid-plastic pseudo-spectra for design purposes.