Quantifying the effects of various uncertainties on seismic risk assessment of CFS structures

This paper systematically investigates the various uncertainties involved in seismic analysis of cold-formed steel (CFS) structures, and aims to provide information for seismic risk assessment and risk-based decision-making of CFS structures. Numerical model of a typical 6-story CFS building is established in this paper, the various uncertainties are analyzed and quantified. The seismic risk of the building in servicing life is calculated, including: (a) the uncertainty in defining the performance limit is proposed, and it is quantified by statistical analysis on cyclic test data; (b) the error on displacement response between the test and the prediction is selected to calculate the modelling uncertainty taking the basis of statistical analysis; (c) the logarithmic standard deviation of the structural uncertainty is recommended as 0.15–0.25 due to the calculating process is complicate and the value has certain regularity, and the engineers could select the final value according to the constructional conditions and environment of the buildings. The results show that the effects of the uncertainty in defining the performance limit and the record-to-record uncertainty on seismic risk of the CFS building are larger than the effect of the structural uncertainty; more efforts are desired in improving the modelling method; in contrast to the case considering the record-to-record uncertainty only, the collapse probability in 50 years of the case considering various uncertainty increases 133%. This paper recommends that the various uncertainties should be considered in seismic risk assessment of CFS structures, and the methods for calculating these uncertainties are proposed in this paper.