Multi-scale numerical analysis on dynamic response and local damage in long-span bridges

This paper aims to develop an approach for multi-scale numerical analysis on structural dynamic response and local damage in long-span bridges. The strategies of finite element modeling of long-span bridges for multi-scale numerical analysis was first investigated. A multi-scale model of the Tsing Ma Bridge (TMB) was then developed based on the design drawings and proposed strategies for multi-scale modeling. The procedures for multi-scale numerical analysis on the dynamic response and local damage are proposed, in which local deterioration processes at welded details of interconnects are able to account for the major effect of the damage and nonlinear influence on structural response. The multi-scale computations are implemented based on the software ABAQUS and the developed programs via the user interface provided by the software for the purpose of easier application to large civil structures. The accuracy of the calculated procedures is addressed with two smaller controlled examples before the approach can be applied to the Tsing Ma Bridge. Based on the online monitoring data acquired from the Structural Health Monitoring (SHM) system installed on TMB, the global dynamic response of the bridge and local damage accumulation of two typical weld details in the longitudinal truss of TMB under traffic loading are numerically analyzed by using the developed model and computational procedures. The maximum value of the accumulated damage is found on the toe of the weld of the upper and/or bottom chords with the diagonal and gusset plate intersection. The fatigue life obtained from the fully coupled calculation is smaller than that from the uncoupled computation, which suggests that the significant interaction between the damage and the structural response should be considered in the structural damage analyses using the multi-scale numerical computation.