Postprint version. Published in Earthquake Spectra, Volume 21, Issue 3, August 1, 2005, pages 653-654.
Copyright © 2005 Earthquake Engineering Research Institute. This article may be downloaded for personal use only. Any other use requires prior permission of the Earthquake Engineering Research Institute. The definitive version is available at http://dx.doi.org/10.1193/1.1979501.
The objective of this investigation is to evaluate the FEMA-356 Nonlinear Static Procedure (NSP) and a recently developed Modal Pushover Analysis (MPA) procedure using recorded motions of four buildings that were damaged during the 1994 Northridge earthquake. For this purpose, displacements and drifts from the FEMA-356 NSP and the MPA procedures are compared with the values “derived” from the recorded motions. It is found that the FEMA-356 NSP typically underestimates the drifts in upper stories and overestimates them in lower stories when compared to the recorded motions. Among the four FEMA-356 distributions considered, the “Uniform” distribution led to the most excessive underestimation or overestimation indicating that the need to carefully reevaluate the usefulness of this distribution in the FEMA-356 NSP. Furthermore, FEMA-356 distributions failed to provide accurate estimates of story drifts for a building that satisfied the FEMA-356 criterion for detecting the presence of higher mode effects indicating the need to carefully re-examine this criterion. The MPA procedure, in general, provides estimates of the response that are much closer to the values from the recorded motion compared to those from the FEMA-356 NSP. In particular, the MPA procedure, unlike the FEMA-356 NSP, is able to capture the effects of higher modes. For a building that exhibits dominant effects of “soft” first story, however, neither the MPA procedure nor the FEMA-356 NSP led to reasonable estimate of the response.
Civil and Environmental Engineering