Finite element modeling of long suspension bridge for structural state assessment

A framework is presented for construction and validation of a finite element model of long span bridge for structural state assessment. Some basic problems for establishing an effective bridge FE model were discussed. As a case study, a FE model of the Tsing Ma Bridge (TMB) in Hong Kong was constructed. The bridge tower was modeled as equivalent space beam with various section properties. A special material with no compression was adopted to simulate the no compression deformation property of the main cables and hangers. With using the response equality method, the geometrical orthotropic steel decks were represented as orthotropic slabs with identified parameters. Constrained equations were formulated to connect the refined FE model of critical locations with the beam-style elements of structural members. Boundary conditions were also considered carefully. Verification of the model was presented with online measured data. Dynamic response of the TMB under a running train is then simulated with the established FE model. The results show that the train speed affects the girder displacements distinctly, but almost takes no effects on the stress level in structural elements.