Effect of nonlinear modeling approaches used for composite elements on seismic behavior of composite framed buildings

This study aims to assess the effect of nonlinear modeling approaches used for frame elements while appraising the seismic performance of the composite moment resisting frame (CMRF) buildings. To this, the accuracy and efficiency of two representative numerical models (namely, inelastic force-based frame element-distributed plasticity (DP) and inelastic force-based frame element-plastic hinge length (PHL) (lumped-plasticity)) for the columns and beams of CMRFs are evaluated comparatively. The number of stories of the buildings of the case study ranges from 5 to 15 and consists of columns made of concrete-filled steel tube sections and CMRFs designed with composite beams consisting of a combination of solid reinforced concrete slabs and steel beams. The structures are designed by considering high ductility level. Seismostruct software is used for design and performance analysis. During the performance evaluation of the structures, the nonlinear static pushover analysis is utilized as well as the incremental dynamic analysis. While performing the nonlinear static pushover analysis, the lateral loadings with uniform and triangular load distributions are used, and moreover, a series of earthquake ground motions are used in the incremental dynamic analysis. To evaluate the effect of the modeling approaches, the seismic response of the structures is assessed by comparing the load-displacement response, energy consumption, performance limit. Additionally, the behavior factor, dynamic behavior factor, inherent strength and overstrength factors, ductility factor and global yield value are discussed.