Enhancing the seismic performance of building structures equipped with composite braces in mega bracing configuration

Abstract

SummaryIn this research, a new passive vibration control system for building structures is presented. The proposed system improves the seismic performance of non‐moment steel structures using the ultra‐high‐performance concrete‐filled steel tube (UHPCFT) braces. In this system, pre‐tensioned tendons are considered to equalize the tensile and compressive capacity of the brace members which are installed as large scale concentrically braced frames (CBFs) (i.e., mega bracing frames [MBFs]) in order to minimize the induced forces in the other structural elements (i.e., beams, columns and slabs). To investigate the feasibility of the proposed system, three 8‐, 12‐, and 15‐story structures are considered. Also, buckling restrained braced frames (BRBFs) and normal concrete filled steel tube (NCFT) braces are considered for the comparison purposes. Furthermore, the effectiveness of the proposed technique is evaluated considering the performance point values and fragility assessment results calculated using a near‐field pulse‐like earthquake record set. Comparison of the simulation results demonstrates that, for all the considered earthquake records, the proposed system remarkably attenuates the structural demand value and collapse probability for all the considered structures. Also, it has demonstrated that type of the nonlinear analysis affects the damage mode.