Condition-assessment-based Finite Element Modeling of Long-span Bridge by Mixed Dimensional Coupling Method

Visual inspection has showed distinct limitations in practical application in condition assessment procedure of large civil infrastructures. The real condition of structure thus greatly depends on an accurate finite element model considering initial defects and deteriorating progress. For the purpose of fatigue damage evaluation of these structures, usually a global structural analysis using a global FE model is first conducted to determine the critical locations, based on which local analysis is then carried out to obtain the hot-spot stress distribution that is commonly considered as the fundamental information for the condition assessment. Since the structural characteristics behaved at the different scales, a mixed dimensional coupling method is obviously necessary and implemented by merging typical detailed joint geometry model into the global model so that the hot-spot stress could be directly output through a single step of analysis. As a case study, a multi-scale model of Tsing Ma Bridge (TMB) is then developed by aforementioned coupling method. The comparison of dynamic characteristics and static responses in term of first few natural frequencies and vertical displacement influence line data respectively between the calculated results and monitoring data indicated that the mixed dimensional coupling method adopted in this paper is convenient and appropriate, and even reliable and accurate for the purpose of condition assessment of long-span bridge structures. The accumulative fatigue damage due to the typhoon York showed that it is much severer than that caused by normal traffic loading, which indicated more attentions should be made after these ultimate events occurred.