Developing structural design criteria with specified response reliability

The objective of developing response-based risk-consistent design criteria is to ensure that design combinations of environmental or load variables are chosen in such a way that one or more structural response variables meet a target level of reliability. Four general approaches are identified: the method of response statistics, methods based on iterative forward reliability analysis, methods based on inverse reliability analysis, and contour methods. The last approach is the only one that provides uncoupling between the probabilistic processing of the environmental and loading variables and the structural response analysis. Two contour methods are described, one based on the inversion of FORM spheres and the other on linearization of an arbitrary response function. Contour methods can easily provide compensation for the effect of uncertain statistical, loading, analysis, and resistance models as well. This is the technique of "inflated contours." Examples are provided describing the use and the quality of the iso-reliability contour techniques. A valuation of criteria such as computational ease, uncoupling between environmental statistics and structural response, repeated use, and incorporation of secondary uncertainties leads to the conclusion that the method of iso-reliability contours is the most effective tool for developing response-based risk-consistent design criteria.