Reliability evaluation in seismic design:: A response surface methodology

Performance-based seismic design requires consideration of the uncertainties in corresponding demands and capacities. A response surface methodology is used to evaluate the annual exceedance probability in each specified, damage-related performance level. The nonlinear dynamic response of the structure to the seismic action is studied considering, among the uncertainties, the peak acceleration and the frequency content of the ground motion. Advantages and disadvantages of two types of response surface formulations are discussed, including two ways of considering dispersion produced by different ground motions. The procedure is illustrated with two examples: an elevated water tank and a five-story portal frame. Finally, the method is applied to the calibration of a deterministic, factored design code approach with multiple performance objectives.