Improving the performance of concentrically braced frame utilizing an innovative shear damper

Abstract

Concentrically braced structures are one of the most common resistant systems in steel structures due to their high stiffness and lateral strength. However, when these structures are subjected to moderate and severe earthquakes, their compression member begins to buckle. Also, buckling of compression members in Concentrically Braced Frames (CBFs) decreases ductility and degradation of the hysteresis curve. Numerous studies have been performed to improve the behavior of CBFs. Using steel dampers is considered one of the appropriate ways to improve the behavior of CBFs. Although steel dampers improve the hysteretic behavior of the CBFs, they impose additional costs on structures. Therefore, in this paper, a steel damper with a shear yield mechanism is introduced, which in addition to being economical, has the ease of construction and replacement after an earthquake. The numerical results indicate an enhancement of the hysteretic behavior of the CBFs utilizing the proposed damper. The main goal of equipping CBFs with the proposed damper is to control the possible damage in the damper and to ensure the elastic behavior of other structural components. The results indicate that the proposed damper can act as a structural fuse by dissipating more than 99% of the system energy and concentrating most of the plasticity and damage, which effectively protect the main structural components from damage while being subjected to seismic excitations. Necessary relations are presented for designing this damper. Besides, a simple method is presented for estimating the nonlinear behavior of the braces equipped with the proposed damper without any need for finite element modeling.