Assessment of Seismic Behavior Factor of Code-Designed Steel–Concrete Composite Buildings

In this study, the seismic behavior factor of steel–concrete composite buildings was examined. For this purpose, 5-, 10-, 15- and 20-story composite moment-resisting frame (CMRF) buildings having concrete-filled steel tube columns and composite beams were designed at medium ductility (DCM) and high ductility (DCH) levels as per the regulations of Eurocode 8. Examined DCM structures were designed for a PGA of 0.2 g while DCH structures were designed for a PGA of 0.4 g. SeismoStruct software was utilized in the design and performance assessment of the case study structures. Nonlinear static pushover and incremental dynamic analyses were used. In the pushover analysis, the uniform and triangular load distributions were adopted while 12 earthquake ground motions were employed in the dynamic analysis. The effect of ductility levels and number of stories on the seismic behavior of CMRFs was studied using the results of the nonlinear analysis. To this, the variation in the lateral response, global yielding value, code-based behavior factor and component, and dynamic behavior factor were presented for CMRF structures with DCM and DCH. It was observed that the behavior factor of all CMRFs exhibited well above the design assumptions, especially DCM class CMRFs.