CHOICE OF A VECTOR OF GROUND MOTION INTENSITYMEASURES FOR SEISMIC DEMAND HAZARD ANALYSIS

摘要

Among the challenges of performance-based earthquake engineering is estimation of the demand on astructure from a given earthquake. This is often done by calculating an 'Intensity Measure' (IM) for agiven earthquake ground motion, and then computing the probability that the earthquake will cause agiven level of demand in the structure as a function of this IM. Traditional IMs include peak groundacceleration and spectral acceleration at the first-mode period of vibration. These IMs consist of a singleparameter. In this paper, IMs consisting of two parameters are proposed: spectral acceleration at the firstmodeperiod of vibration along with a measure of spectral shape (the ratio of spectral acceleration at asecond period to the original spectral acceleration value). A method for predicting the probabilitydistribution of demand using a vector IM is presented. This method accounts for the effect of collapses onthe distribution of demand. Two complimentary methods for determining the optimum second period at agiven intensity level are described, and an improvement in the accuracy of demand predictions is shown.