A new friction–slip brace damper to improve seismic performance of braced frames

Abstract

Global buckling in compression braces results in compression strength degradation, compression stiffness degradation, brace local buckling, and finally brace fracture. Consequently, the braces cannot achieve high energy dissipation capacity. The current study proposes a novel friction−slip damper employed in the middle of square−Hollow Structural Section (square−HSS) and H−shaped braces to prevent the strength and stiffness degradation of braces and improve their seismic responses. In these braces, slip prevents the global buckling of brace and friction dissipates a large portion of energy. To assess the performance of proposed damper, the hysteresis behaviors of square−HSS and H−shaped braces with the proposed friction−slip damper were compared with those of conventional braces both in bracing elements and in diagonal and chevron Special Concentrically Braced Frames (SCBFs) through modeling the numerical models in ABAQUS finite element software validated with two experimental studies. The study findings showed that in the models equipped with the friction−slip damper, the braces experienced no global buckling, local buckling, yielding, plastic hinge, damage, and fracture. Additionally, the obtained results indicated that no degradation was observed in the strength and stiffness of the models with the friction−slip damper than the conventional models. Consequently, a 186.3% increase in energy dissipation capacity was experienced by installing the proposed damper in the middle of braces. Moreover, the results showed that the beams of chevron SCBFs with the friction−slip damper experienced no unbalanced force and thus, no deflection resulting in the stiffness and strength degradation in the tension and compression braces was observed in the chevron beams.