Gravity Dam Based On Ansys Structural System Reliability Analysis

Structural reliability theory as a new and advanced design theory, play an increasingly improtant role in improving structural design specification and developing design methods. Subjected to many random factors combing effect, such as hydraulic pressure and silt pressure, uplift pressure, the dam and its foundation material properties and so on, to make research on them is accacepted considerable attention. With simple structure and good adaptability to foundation and so mang virtue, Gravity dam turned to be the nost universal adoption dam type. Once wreck of a large gravity dam happened, the consequences will be incalculable, it is necessary to study the reliability of the gravity dam. Gravity dam could be considered as three-dimensional of hyperstatic structure made up of many elements, therefore, evaluation of its system reliability should be carried out to examine the reliability of the whole structure.This paper builds two-dimensional finite element model of gravity dam and carrys out the system reliability analysis based the large commercial finite element software ANSYS with its strong pre-processing, solution, post processing,PDS design function and so on, considering gravity dam failure as a series system composed of body strength failure, foundation failure and sliding stability failure three main failure modes, and every failure mode a parallel system of many elements. For making analysis of the gravity dam system reliability, this paper uses response surface method to fit function expression of one elment; uses Geometry Approach to get the reliability index and linear expression; when one element disabled, takes birth and death of element technology to change its state; uses equivalent linearization method to get the probability of two elements failed together and chooses the next failure element with conditional reliability index, ultimately, all paths and failure probability are obtained. When information above gotten, boundary method is employed to estimate the failure probability of the whole system. The example reveals that, making structure analysis based on ANSYS, fitting single element function with response surface method, adopting element birth and death and conditional reliability index concept to search the failure paths and failure probability estimate, obtaining system failure probability with boundary method could achieve good effect to analyze gravity dam structure system reliability.