LAUSR

Abstract The influence of steel brace buckling on inelastic torsion of steel braced concrete frame structure is studied. On the background of a project, the shaking table test results of two structural models with ordinary steel brace (BRC) and buckling-restrained brace (BRB) are compared, and the inelastic torsion and sudden increase caused by steel brace buckling is confirmed. Finite element analysis models with BRC, BRB and floor load eccentricity are established, in which the restoring force model of steel brace considered the asymmetry of tensile and compressive bearing capacity, and the concrete beam and column members considered M3 and PMM hinge respectively to study the process and characteristics of the influence of BRC buckling on the nonlinear torsion of the structure. The mechanism of inelastic torsion of steel braced concrete frame structure (F-BRC) induced by BRC buckling is studied, and the principle that the dynamic BRC buckling makes the structure acquire inertial force as well as inertial torsion moment is found out. It is more reasonable to explain the inelastic torsional process and the mechanical characteristics of the structure by this principle than by the theory of strength eccentricity and stiffness eccentricity. Finally, based on the principle, six numerical examples with different brace schemes under the excitation of eight earthquake waves are calculated, and the changing rules of the torsional moment are studied. Some design limitation suggestions are put forward.