Structural system reliability: A study of several important issues.

摘要

Three important issues in structural reliability analysis and design are studied in this thesis.; A prerequisite for reliability-based code calibration is the ability to compute modal failure probabilities. Three definitions for modal failure probability which are currently used by engineers, explicitly or implicitly, are shown to yield quite different results. A methodology based on mathematical programming techniques is proposed to identify systematically the dominant failure modes of a complex structure when the loads are stochastic processes.; Despite the inherent advantage of providing an upper bound on the system failure probability, {dollar}Psb{lcub}f{rcub}{dollar}, the static approach for reliability analysis of rigid-plastic structures has received very limited attention compared to the kinematic approach. The static approach is studied in detail, with particular attention given to its relationship to the kinematic approach. A mathematical programming algorithm is developed to compute an upper bound for {dollar}Psb{lcub}f{rcub}{dollar}. Many properties of this bound observed from numerical examples are readily explained in the basic variable space and the redundant force space. Guidelines on selecting the best starting points and redundant forces are also proposed, two of which are of particular interest. One relates to the equivalence of two redundant force sets, and the other to the possibility of obtaining better results using multiple redundant sets.; As a step toward the goal of developing general reliability methods for load path-dependent problems, some fundamental concepts such as limit state surface are recast in the context of load path-dependency. New concepts are introduced to help in the understanding of path-dependent reliability problems.