SEISMIC VULNERABILITY OF FLAT SLAB-CORE BUILDINGS

This paper presents the seismic vulnerability evaluation of a 27-story reinforced concrete fiat slab-core building, which had not been desig ned for seismic forces. The evaluation is based on the FEMA-178 handbo ok in conjunction with structural identification by modal testing and sensitivity analyses. Experimentally determined dynamic characteristic s and lateral flexibility are used to develop and calibrate a three-di mensional (3D) analytical model. Response spectrum sensitivity studies are conducted. The parameters that influence the degradation of the l ateral stiffness under seismic loading are considered for predicting p ossible demand envelopes under expected and maximum credible earthquak es. Evaluation of demands versus capacities at the element level indic ates that the building is adequate for FEMA-178 specified forces but v ulnerable to the maximum credible earthquake. Exterior slab-column con nections are found to be the weakest links in the building. Investigat ion of the failure behavior of the building during its implosion is al so presented. Problems in the application of FEMA-178 to buildings typ ical of the midwestern and eastern United States are and suggestions f or improvement are presented.