09-10-2014, 02:37 PM
In this study, a new set of response spectra are proposed using a series of vertical cantilever beams discredited as MDOF systems. This is in contrast to the response spectra derived based on a series of SDOF systems. Three strong ground motions having different characteristics have been analysed. The proposed spectra based on MDOF systems also incorporate the type of deformation induced in the structure, i.e., flexure-type, shear-type or combined flexure-shear type. For the ground motions studied, the ratio of the spectral displacement (and the pseudo spectral acceleration) from the MDOF spectra to that from the SDOF spectra is about 1.75 in flexure-type buildings and about 1.4 in shear-type buildings. The spectral displacements from the MDOF spectra decreases with increase in , a parameter reflecting the relative translation stiffness contributed by flexural and shear deformations, and is about 1.25 times more in case of flexural-type buildings than those in shear-type buildings. The ratio is reasonably constant in the long period range suggesting that the PSA spectra