Seismic robustness of self-centering braced frames suffering tendon failure

Abstract

This paper comprehensively discusses the behavior and failure risk of self-centering braced frames suffering tendon fracture. The fundamental mechanism of tendon failure in self-centering braces (SCBs) is first introduced, followed by the design and analysis of a series of prototype buildings with different tendon materials and brace configurations. Assuming a normal distribution of tendon fracture strain, the dynamic behavior of the frames is then assessed by a suite of ground motion records, covering both far-field and near-fault ones. The collapse and residual deformation fragilities of the frames are further evaluated, and the study ends with a risk assessment considering a 50-year service period. Among other findings, the study indicates that tendon fracture tends to increase the peak interstory drift, especially for the structure with smaller tendon fracture strains. Tendon fracture also compromises the self-centering capability significantly, although there is no obvious statistical correlation between tendon fracture and the peak floor acceleration. The probability of collapse and that of exceedance of certain residual drift both increase evidently when tendon fracture is considered. The failure probabilities are closely related to the available deformability of the SCBs, where dual-core SCBs show less sensitivity to tendon fracture. The probability of collapse of the considered frames over 50 years of service increases from 1.25-2.12% to 3.58-6.52% when tendon fracture is considered. Considering a residual drift threshold of 0.5%, the probability of exceedance of the same structures over the same life span increases from 1.78-3.54% to 5.46-9.71%.