Seismic evaluation of unreinforced masonry structures with flexible diaphragms

A discrete linear-elastic, multi-degree-of-freedom (MDOF) dynamic model developed for the dynamic analysis of unreinforced masonry (URM) structures with flexible diaphragms is presented. The discrete MDOF dynamic model represents the dynamic response of the structure in a given direction by a reduced number of discrete masses associated to translational degrees of freedom acting in that direction. The discrete model considers the flexibility of the diaphragms and the rotations of the walls, which are included into the global translational degrees of freedom through static condensation. Soil-structure interaction effects can be easily incorporated in the method. The applicability of the method in the study of the dynamic response of a URM structure with flexible diaphragms is presented. The structure, an old firehouse located at Gilroy, California, has been instrumented by California Strong Motion Instrumentation Program (CSMIP). Instrumented records of the dynamic response of the firehouse of Gilroy during the Loma Prieta Earthquake are available. The firehouse survived the earthquake with little damage. The discrete dynamic model presented in this work has been able to reproduce well the recorded dynamic response of the firehouse of Gilroy during the Loma Prieta Earthquake. © 1992 Earthquake Spectra.