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%.

Self-Centering Shape Memory Alloy-Viscoelastic Hybrid Braces for Seismic Resilience

“…Therefore, the SMA cables always remain in tension no matter what condition state the brace is in, giving full play to the performance of the SMA cables. Previous studies have verified that the SMA-based elements/components are expected to exhibit a flag-shaped response [ 67 , 74 , 75 , 76 ]. An idealized/simplified force-displacement relationship is adapted here to capture this unique hysteresis evolutionary path (see Figure 3 a), where four stiffness parameters, namely k 1 for loading stage, k 2 for loading plateau stage, k 3 for unloading stage, and k 4 for unloading plateau stage, are considered [ 77 ].…”

Probabilistic seismic evaluation of SMA‐based self‐centering braced structures considering uncertainty of regional temperature

“…These factors contribute to added flexibility of SCB and affect its initial stiffness 51 . According to a comprehensive survey of the existing experimental programs, 52 the initial “elastic” deformation of a single‐core SCB seems to fall in a range between 2.0 and 3.0 mm. Therefore, an initial deformation of 3.0 mm is consistently employed for all the braces to estimate the value of the initial stiffness .…”

The effect of vertical near-field ground motions on the collapse risk of high-rise reinforced concrete frame-core wall structures

“…Then, IDA curves, in which an engineering demand parameter (EDP) is plotted as a function of IM, can be generated (Vamvatsikos and Cornell, 2002). IDA procedure has been widely accepted and used to assess the seismic performance of various structural systems, including steel SMRF (Elkady and Lignos, 2014; Vahedi et al, 2021), braced steel frames (Karavasilis et al, 2007), RC SMRF (Goulet et al, 2007), foundations (Zafeirakos et al, 2013), corroded RC frames (Dizaj et al, 2018), high-rise towers (He and Lu, 2019) and self-centering braced frames (Ping et al, 2021). Conducting IDAs, fragility curves, which are the conditional probability of exceeding the limit state capacity for a given level of IM, can be derived as a cumulative distribution function (CDF) (Ibarra and Krawinkler, 2004).…”