Experimental study on cyclic behavior and failure mechanism of self-centering braced steel frame

This paper presents an experimental study of a 1/2-scale, 3-story, 1-bay self-centering braced frame (SBF) under quasi-static cyclic loading. The working mechanism of the self-centering (SC) brace from activation to destruction is described. The seismic performance, damage development, and failure mode of the SBF were investigated. The influence of the inner tube's yielding and the flattening of the disc springs on the SBF's seismic performance and SC behavior was analyzed. The test results indicated that the SC braces maintained the residual story drift ratio of the SBF within the repair limit when the inner tube of the SC brace was in an elastic state despite column yielding. The disc springs flattened only when the SC brace was in compression, substantially increasing the brace's stiffness and force. The yielding of the inner tube in tension limited an increase in the brace force, resulting in increased residual deformation and double activation of the SC brace. The SC brace exhibited an asymmetric hysteretic response when the inner tube yielded. The chevron bracing pattern ensured a high story shear of the SBF but resulted in the beam's vertical deformation and yielding. The hysteretic response of the SBF in Story 1 changed from flag-shaped to parallelogram-shaped with an increase in plastic deformation of the columns and inner tubes. The SC braced system is an alternative to traditional braced systems for building resilient cities because it exhibits lower damage and residual deformation.