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On Inelastic Response Spectra for Aseismic Design.
Lai, S. S. P.; Biggs, J. M.; Vanmarcke, E. H.
National Science Foundation, Washington, D.C. Div. of Advanced Environmental Research and Technology., July 1978, 155 p.
Identifying Number(s)
['R78-18', 'MIT-CE-R78-18']
The sources of variability in inelastic response spectra, namely, strong ground motion duration, ductility level, and viscous damping ratio, are investigated. From time history analysis, it is concluded that the Newmark inelastic response spectrum for elasto-plastic systems are unconservative for 5% damping, and conservative for 2% damping. By comparing the 'inelastic response ratios,' new inelastic response spectra are proposed. Based upon simulation studies, semi-empirical modifications to an elasto-plastic random vibration model are suggested. The resulting probabilistic predictions of the inelastic response are quite compatible with those obtained by time history analysis. Three steel moment-resisting frames are analyzed to assess the validity of the modal analysis-based inelastic frame design procedure. The results indicate that this design procedure of using the proposed inelastic response spectra yields better frame designs than those based upon the Newmark spectra. However, the procedure results in conservative design for interior columns and girders, and unconservative design for upper story exterior columns.
FRIEDA computer program; Seismic design; Earthquake resistant structures; Framed structures; Earth movements; Elastic analysis; Dynamic response; Ground motion; Earthquake engineering; Seismic risk analysis; Buildings; Random vibrations; Computer aided design; Soil mechanics; Earthquakes; Dynamic structural analysis