Condition Assessment Of Long-span Cable-stayed Bridges Based On Multi-scale Finite Element Modeling

With the development of economy and the progress of the Times,long-span cable-stayed bridges are becoming one of the important bridge structures.With increasing of the lifetime,the damage is gradually appeared and expanded in bridge structures.If national evaluating and repairing are not taken in time,severe consequence will be result in.For this reason,in operation state,the research of the evaluating in long-span cable-stayed bridges is becoming important increasingly.Therefore,the article carried out a few research aiming at this problem listing as follows:1.Refer to corresponding codes and literature,starting from structural lifetime of long-span cable-stayed bridges and considering influence of lifetime,the time-dependent analytic hierarchy process(AHP)is initially established in this article for structural condition rating of long-span cable-stayed bridges.Time influence coefficient is defined based on time-dependent reliability,then the time-dependent AHP is stated.Contrasting this method and traditional AHP,the time effect is highlighted.Time impact factor is determined based on time-dependent reliability,which has improved time-dependent AHP.By comparing and analyzing the weight with different time,it is shown that the influence of time on the rating of long-span cable-stayed bridge cannot be ignored.2.In this thesis,the author has established local details multi-scale finite element model(FEM)with the researching background of the long-span cable-stayed bridge.The method used different scale elements to simulate different scale indices,such as weld metal,structure type of components and structure group,etc.What's more,consequence of all scale structures can be obtained in the same model through calculating by one time.That can not only carry out analysis of the full bridge,but local analysis and detailed analysis as well.The local details multi-scale FEM has been verified in this article,and the model can satisfy the requirements of the structural condition assessment.3.Long-span cable-stayed bridges have been rated in condition by utilizing the time-dependent analytical hierarchy process basing on three-level multi-scale FEM of the long-span cable-stayed bridge.7 loading modes are confirmed through FEM with referring to codes and literature.Every index of the long-span cable-stayed bridge has been rated by the method.The result of Analysis shows that the consequence of condition rating is more accurate and effective by using the time-dependent AHP and considering structural lifetime.