Performance and design of double cross-arm cable-stayed buckling-restrained braces with fix-ended stays

Abstract

As inspired from a double-arm pre-tensioned cable stayed column (PCSC), a concept of a double-arm pre-tensioned cable stayed buckling-restrained brace (DPCS-BRB) is put forward through adding the core inside PCSC. But a previously published paper only limited into the DPCS-BRBs that have pin-ended stays and their practical application is limited undoubtedly. Therefore, this paper focuses on DPCS-BRBs with fix-ended stays and investigates into their structural performance and design through theoretical derivation and Finite Element Analysis (FEA). With fix-ended stays in the DPCS-BRBs, flexural rigidity and deformations of the stays must be considered in both elastic and elastoplastic FEA of DPCS-BRBs. The design method in obtaining the lower limit value of restraining ratios should be re-established by considering the fix-ended stays. Firstly, this study explores elastic buckling behavior of DPCS-BRBs, focusing on explicit formula prediction of the elastic buckling load under either symmetric and antisymmetric buckling mode by using energy method. The obtained theoretical formulas are then validated through FEA. And then, the static load-carrying behavior and hysteretic performance of DPCS-BRBs are investigated by employing elastoplastic FE models that were validated by experimental tests conducted previously by the authors. Finally, because the possible existence of asymmetric imperfection interaction between two possible aforementioned buckling modes would lead to reduction in the load-carrying capacity, therefore, interactive buckling must be considered for establishing conservative design method of DPCS-BRBs, particularly where prestressing force of cables is involved. The research outcomes attained would provide structural design guidance in engineering applications of DPCS-BRBs with fix-ended stays.