Performance Testing and Cyclic Behavior of Buckling-Restrained Braces with H Cross Section Unrestrained Segments

Abstract

The hysteretic behavior of four buckling-restrained braces (BRBs) with H cross section unrestrained segment was tested under cyclic load. The transformation of the unrestrained segment's section from crisscross shape to H shape can improve the moment-resistance capacity of unrestrained segment significantly and avoid buckling instability of unrestrained segment effectively due to evident stiffness enhancement. BRBs were designed according to Chinese codes, the load-carrying elements of BRBs were fabricated with Chinese Q235 steel. In the process of experiment, BRBs did not buckle, BRBs could undergo fully-reversed axial yielding cycles without loss of stiffness and strength, the ductility and energy absorption capacity of BRBs are large enough to withstand major earthquake. The resilience model can be simplified to a symmetrical bilinear resilience model. The ratio of width to thickness of inner core has a little influence on the mechanical behavior and energy-dissipation capacity of BRBs. A suggestion for design improvement of BRBs was proposed according to the failure modes of BRBs.

Experimental investigation of miniature buckling restrained braces for use as structural fuses

“…The cross-sectional shape of the inner steel core can vary (e.g. Jia et al [9]), but typically the yielding segment of the core is a plate with rectangular section. To minimize friction between the core and restraining member, several kinds of debonding material [10,11] or air gap have been used [12][13].…”

Low-cycle fatigue life evaluation of buckling-restrained braces based on cumulative plastic deformation curves

“…In addition, it was suggested that when steel moment-resistant frames (SMRFs) were subjected to design-based earthquakes (DBE) ground motions (10% in 50 years), the residual drifts of SMRFs were varied from 0.5% to 1.2% (Adeli et al, 2012). Many research results show that the low-cycle fatigue failure of steel in structures will eventually be caused by cumulative damage (Afsar et al, 2018; Jia et al, 2014; Krawinkler and Zohrei, 1983; Li et al, 2019). In view of this, the low-cycle fatigue life of BRBs needs to be extensively and quantitatively investigated.…”

Performance testing and comparison of buckling-restrained braces with H and crisscross cross section unrestrained segments

“…Results from a comprehensive experimental program (Merritt et al, 2003;Xie, 2005;Jia et al, 2014) BRBs deliver ductile, stable, and repeatable hysteretic behavior, and the plastic deformation capacity of the braces exceeds the specified requirements in terms of both ultimate deformation and cumulative plastic strain. Ju et al (2009) conducted component tests on the effect of the thickness of the constraining tube and the length of the unconstrained length of the H-shaped core ends on the maximum strength and the energy dissipation capability of BRB.…”