Seismic behaviour of steel Chevron bracing systems by non-linear dynamic analyses

The paper focuses on steel Chevron concentric bracing systems (CBF-V) as seismic resistant structures, presenting the evaluation of the structural seismic performance through dynamic analyses, aimed at improving the design methods. A wide numerical study is carried out. Different CBF-V configurations are designed, for a total number of 12 structures, by varying number of storeys (3, 6, 10), design methods (linear and dynamic analysis) and braces sections (H-shaped and circular hollow sections). Nonlinear Incremental Dynamic Analyses (IDA) are performed by the SeismoStruct software, considering 7 earthquakes records, in order to investigate the seismic response. The most relevant evaluation parameters are shown and discussed, IDA curves are caught and the behavior factors calculated. Results show that expected collapse modes, involving the braces only, according to the Capacity Design, are not in agreement with the noted mechanisms, in which damage also involves non-dissipative elements, in particular the beams. Hence, it is needed to deepen such key issue, through further experimental and numerical investigations in order to optimize the design procedure.