Uniform fragility spectra for the performance‐based seismic design of structures considering variabilities in structural properties

Abstract

Summary This paper presents a new methodology based on structural performance to determine uniform fragility design spectra, i.e., spectra with the same probability of exceedance of a performance level for a given seismic intensity. The design spectra calculated with this methodology provide directly the lateral strength, in terms of yield‐ pseudo‐accelerations, associated with the rate of exceedance of a specific ductility characterizing the performance level for which the structures will be designed. This procedure involves the assessment of the seismic hazard using a large enough number of seismic records of several magnitudes; these records are simulated with an improved empirical Green function method. The statistics of the performance of a single degree of freedom system are obtained using Monte Carlo simulation considering the seismic demand, the fundamental period, and the strength of the structure as uncertain variables. With these results, the conditional probability that a structure exceeds a specific performance level is obtained. The authors consider that the proposed procedure is a significant improvement to others considered in the literature and a useful research tool for the further development of uniform fragility spectra that can be used for the performance‐based seismic design and retrofit of structures.

Estimation of Uniform Risk Spectra Suitable for the Seismic Design of Structures

“…Such seismic source is the Guerrero Gap, one of the most studied seismic zones by seismologist and civil engineers [58,59]. The earthquake generation model for the subduction zone of Guerrero is described using a characteristic earthquake model [60], whose parameters are T00 = 80 years, Mo = 7.0, Mu = 8.4, D = 7.5, F = 0, σM = 0.027, and T o = 39.7 years [39,60]. Figure 3 shows the estimated exceedance rate of magnitudes curve for the Guerrero Gap.…”

“…Other types of spectra are oriented to achieve uniform rates of exceedance of engineering design parameters [33][34][35][36][37][38][39], such as damage indexes, damage states, or fragility approaches. These spectra are obtained from a statistical analysis of the SDOF response under seismic actions derived from seismic records, and they predict, with a good ap-proximation level, the seismic performance in terms of physical damage.…”