Seismic collapse capacity and dispersion spectra for self‐centering braced frames considering uncertainty propagation

Abstract

AbstractThis paper presents the development and application of seismic collapse capacity and dispersion spectra for self‐centering (SC) systems considering uncertainty propagation. A methodology for uncertainty evaluation is proposed to investigate the influence of material‐to‐system uncertainty on the collapse capacity of SC systems. The probability distributions and the correlation of SC system parameters are derived from statistical data obtained via generating non‐deterministic structural models and performing static push‐over and push‐pull analysis. Based on the uncertainty analysis, the influences of system hysteretic parameters, P‐Δ effect and near‐fault ground motions on the collapse capacity of SC systems are comprehensively investigated. Aided by an extensive parametric study on single‐degree‐of‐freedom (SDOF) systems, predominant factors controlling the collapse capacity of SC systems are revealed. The total dispersion of collapse capacity stemming from various sources including the record‐to‐record (RTR) variability and uncertainty in hysteretic parameters is subsequently quantified. Different definitions of RTR variability are discussed, highlighting the necessity of utilizing the RTR variability involving collapse state. The contribution of RTR variability and the uncertainty in hysteretic parameters are then evaluated by the first‐order second‐moment (FOSM) approach. Furthermore, the design collapse capacity spectra and design dispersion spectra, are developed. The results indicate that the design spectra are capable of estimating the collapse capacity of SC systems, and provide an easy‐to‐use quantification tool for probabilistic seismic assessment.