Performance of the Cold-Bending Channel-Angle Buckling-Restrained Brace under Cyclic Loading

Kun Wang,Bo Xu,Junwu Xia,Xiaomiao Chen,Xiangzhou Liang,Jian Wang

doi:10.1155/2019/9710529

Abstract

In this study, three restricted cold-bending channel-angle buckling-restrained brace (CCA-BRB) specimens were experimentally characterised by a low-reversed cyclic loading test. Three specimens had steel cores with cruciform cross section. Two restraining units were assembled to form an external constraint member, each of which was composed of an equilateral cold-bending channel and two equilateral cold-bending angles via welding. A gap or a thin silica gel plate was set between the internal core and the external constraint member to form an unbonded layer. Several evaluation parameters on the seismic performance, hysteretic behaviour, and energy dissipation capability of the CCA-BRB was investigated, including hysteresis curve, skeleton curve, compression strength adjustment factor, measured and computed stiffness, energy dissipation coefficient, equivalent viscous damping ratio, ductility coefficient, and cumulative plastic deformation. The test results and evaluation indices demonstrated that the hysteretic performance of braces with a rigid connection was stable. A Ramberg–Osgood model and two model parameters were calibrated to predict, with fidelity, the skeleton curve of CCA-BRB under cyclic load. The initial elastic stiffness of the brace used in practice should contain overall portions of the brace instead of the yielding portion of the brace. Finally, all the tested CCA-BRBs exhibited a stable energy absorption performance and verified the specimens’ construction was rational.

Highlights

As a kind of structure system with excellent ductility, the braced frame is often used in seismic structures
Diverse experiments show that buckling-restrained brace (BRB) have a substantial energy absorption capability under cyclic loading [7, 8]
In 1976, an early buckling-restrained attempt to propose a brace with dissipating energy yet does not buckle was reported in an experimental study [9]. e brace consisted of a single flat plate as the internal core and a square steel pipe filled with mortar as the external constraint member

Summary

Introduction

As a kind of structure system with excellent ductility, the braced frame is often used in seismic structures. A buckling-restrained brace (BRB) is an energy dissipation damper of metal yielding which has advantages of stable energy dissipation capacity, easy construction and fabrication with low cost, etc. A BRB can provide stable lateral stiffness and load-carrying capacity for a frame structure. Various structural forms and experimental studies of traditional BRBs were proposed by investigators around the world [10,11,12,13]. There were a series of issues affecting the traditional BRBs, in which the core buckling restrained by steel tube filled with concrete or mortar, such as the need for higher precision control between the external concrete member and the core steel member, and the complex processes of wet concrete pouring, further

Methods

Results

Conclusion