A Study On Structural Stable Reliability

At present, it is generally recognized that almost all structural systems are indeterminate. Structural reliability is to study the safety question of structure under stochastic factor. Great progress has been made in theory and application by applying reliability theory to solve in intensity, stiff and fatigue of structure, but little in buckle reliability. The strength of actual structure is generally decided by stability. Therefore, it has significant application value to study stable reliability of structure. Stable reliability of spar and simple spar system has been studied in this article. Now the main conclusions gained are given as follows.1. Euler critical force of axis pole can be gained by equilibrium differential equation. It can be regard as strength of the stress-strength modal and the load that the pole beared as stress. Applying Hasofer-Lind method has got the reliable index. Using Aitken substitute to Newton iteration can void the possibility of divergence and speed divergence.2. The beam column is loaded by axis press and moment and the moment isn't subsidiary. Both margin yield criterion and elastic-plastic buckle are used to solve the stable reliability of beam column in this article. As for margin yield criterion, the maximum stress of section is regarded as stress of stress-strength modal and yield stress of the material as strength. The elastic-plastic buckle is nonlinear and the utmost load can't be got through analytic result. The reliable index has been gained by Monte-Carlo method.3. The symmetrical rigid frame system can be separated into single component to calculate reliable index. For generally rigid frame, taking buckle into account, boundary branch method is used to looking for main failure modes. The reliability of rigid frame is evaluated by narrow band Ditlevsen method. Because buckle is brittle failure, failure route is related to failure sequence. Thefailure mode is increased evidently when taking buckle failure into account. The sample indicates that failure probability is larger when thing buckle failure and buckle can't be ignored in calculating reliability.