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Approximate Modal Analysis of Bilinear MDF Systems Subjected to Earthquake Motions.
Tansirikongkol, V.; Pecknold, D. A.
National Science Foundation, Washington, DC. Research Applied to National Needs., August 1978, 221 p.
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The study investigated two approximate methods of modal analysis for hysteretic multi-degree-of-freedom lumped mass structural models subjected to earthquakes. The methods were (1) approximate modal analysis using elastic response spectra, and (2) approximate modal analysis using inelastic response spectra. Both modal analysis procedures were iterative and used a perturbation method to successively modify the original elastic mode shapes at each iterative step to reflect yielding in the system. The procedures were developed and evaluated only for shear beam structural systems consisting of members with bilinear hysteresis. Extensive comparisons of exact and approximate responses were made for various 1-, 3- and 10-degree-of-freedom systems. Four existing earthquakes were used, and several structural stiffness and strength parameters were varied. Maximum story displacements were generally predicted within about 5-40 percent accuracy. The equivalent nonlinear approach using inelastic response spectra appeared to give generally better accuracy than the equivalent linear approach using elastic response spectra.
One degree of freedom; Structures; Ten degrees of freedom; Three degrees of freedom; Mechanical hysteresis; Dynamic response; Degrees of freedom; Earthquake engineering; Buildings; Theses; Elastic properties; Earthquakes; Dynamic structural analysis