The Reliability Analysis Of Bridge Structures For Multi-supported Excitations

In recent years, with the development of economy and traffic construction, a great deal of long-span bridge have been build and expanded, especially, the scale of bridge bigger and bigger, the number of high tower and long-span cable-stayed bridge increasing gradually, as the lifeline project, the earthquake resistant design and seismic reliability analysis of bridge structures is become significant.First of all, this paper introduces a great progress has been achieved in the research of structural reliability theories and their applications since the it became a worldwide interest topic. Based on extensive published and research documents, a state of the summary, consisting of structural reliability fundamental theories and approaches, structural system reliability, ultimate and serviceability limit state reliability fatigue and aseismic reliability is presented, improve on the First-Order Second-Moment(FOSM) method for structural reliability analysis aim at over come the shortcoming of difficult to derivation and complicated compute in FOSM method. By virtue of Genetic Algorithms (GA) is convenience to calculate the structural reliability when functions have multi-peak value, in which value convergence in local check point or divergent by FOSM method.After that, the influences on seismic responses of long-span bridges subjected to multi-supported excitations are mainly discussed in this dissertation, and the various effects of spatial variations are included. And to deduce the combination rule for spatially varying seismic motions over again. Based on stationary random vibration theory, analyze the aseismatic reliability of long-span structures by means of response spectrum method, and various response quantities including the both response mean and variance acquired, this method overcome the disadvantage of be incapable obtain variance result in impossible to compute reliability of structures. And in this paper, use the simplified correlation coefficients convenience to computation of reliability, On the other hand, make use of the engineering example with proposed method demonstrated for bridge under multi-support excitationsanalyze the result. And compared to the conventional method, the proposed method has incomparable computational efficiency.At last, based on the orginal data, build the two tower cable-stayed bridge model, some result consist of modality analys and dynamic analys, based on genetic algorithms method and response spectrum method under multi-support excitations analyzing the strucral reliability.