Combined boundary element and finite element analysis of composite bridges.

Abstract

In this thesis, the coupling of boundary element and finite element methods and its application to analyze bridges are studied for the first time. The coupling technique is implemented to analyze slab on girders and box girder bridges. The boundary element method is employed to model the bridge deck while the finite element method is used to model the girders. The finite elements and boundary elements are connected at a number of interface nodes in the longitudinal direction. For the finite element region, a static condensation technique is applied to condense the non-interface degrees of freedom. Then the finite element equations are transformed into boundary element equations and the compatibility interface mechanism required to combine the two methods is developed. A computer program which combines boundary element and finite element methods in one solution is developed in this thesis. Different types of bridges with different load cases are considered in the study in order to test the performance of the combined method. It has been shown that the results obtained by the combined method (BEM-FEM) are in good agreement with the finite strip solution. The numerical examples, considered in this thesis, demonstrated the accuracy of the results and the simplicity and reduction of the input data.