Model‐Correction‐Factor Method in Structural Reliability

Under general conditions reliability analyses of elaborate structural models can be replaced by much simpler equivalent reliability analyses of corresponding idealized structural models such as those based on rigid‐plastic theory. The equivalence is in the sense of being with respect to probability of failure and is obtained by applying a random factor correction of the strength variables of the simple model. This model‐correction factor is called the effectivity factor, and it is approximated to the zeroth order by a constant or to the first order by an inhomogeneous linear function of all the basic variables in the realistic model. The coefficients of this function are calculated from the elaborate model (e.g., by finite element calculations) with values of the input variables chosen on the basis of a first‐order reliability analysis of the simple model (FORM). The model‐correction‐factor method is a special type of response‐surface method based on mechanical principles. It is illustrated quantitatively on a yield hinge frame model with strain softening mutual rotation‐moment behavior in the hinges upon the onset of yielding.