Structural Reliability Analysis Method And Related Theory

The safety of engineering structures is always one of the most important problems in engineering design. The method of engineering design and verification shifts from subjective means guided by experience to limit state design methods based on probability theory with the introduction of the concept of engineering structural reliability. Around calculation methods and related theories on structural reliability, the article proposes two methods on structural reliability analysis, i.e. moment method and intellectual method; It also applies the structural reliability to underground excavation engineering ; and it analyze the affection of different factors that influence the structure.The moment method is improved in this paper. Pearson system is assumed in order to obtain more moments of the performance function. The least square method and the maximum entropy method are utilised to get the probability density function of the performance function. The presented method is demonstrated using numerical examples to be effective for structural reliability evaluation. Moment method is convenient since there is no difficulty with the design point, iteration, and computation of derivatives. Compared with the least square method, the maximum entropy method is a more reasonable way to obtain the probability density function from numerical examples.Structural reliability analysis methods based on intellectual theory are proposed in this paper, too. The performance function with implicit expression is approached with artificial neural network (ANN) (here a comprehensive BP ANN is utilized). Then combined with familiar methods for structural reliability i.e. MSC, FORM, SORM, the reliability index can be gained. According to the geometrical meaning, to identify the structural reliability equals to solve a conditional minimization problem with genetic algorithm (GA). Cases are studied to test the rationality and efficiency of those methods based on intellectual theory.In order to present the status of underground excavation engineering more clearly, the article presents a feasible way to calculate the structural reliability everywhere around caverns. This article combines response surface method, JC method, and advances a simple but practical method—design point method to analyze the structural reliability. Taking caverns of the underground powerhouse of a hydropower station as an example, the article calculates structural reliability of every point and gives the structural reliability contour lines. The result matches with the actual case and can well reflect the safety status of the rock masses around caverns.At last, the article introduces relevance theory in grey system to identify the influence of different factors in structural reliability analysis systems. It provides a new way for evaluation to factors affect the structure.