NONLINEAR DYNAMIC MODEL FOR SEISMIC ANALYSIS OF NON-STRUCTURAL CLADDING

The seismic behavior of moment-frame structures with non-structural cladding in moderate to severe earthquakes has shown that the cladding panels and connections have a significant influence on the overall building response. However, analytical models that simulate the seismic response of structures with cladding have not been fully developed. In this paper we present a finite element model for nonlinear static and dynamic analyses of moment frame structures with cladding elements. These non-structural elements are attached to the structure using a small number of connectors intended to carry gravity loads, in-plane shear, and out-of-plane shear. The attachments are made using all-thread rods with double nuts or field fillet welds between angles, pipes, or plates embedded in non-structural panels and attached to the structure. In the proposed model, the panels are assumed to be rigid elements with a known mass. The attachments are modeled as multi-directional spring elements with cyclic force-deformation properties derived from attachment test data. The characteristics of the proposed model are examined in nonlinear static pushover and nonlinear dynamic time history analyses of the SAC Joint Venture 3-story building. The results show that the inclusion of cladding in the analytical model significantly affects the seismic response of the building.