Nonlinear analysis of composite steel girder bridges

This paper describes a procedure for the nonlinear analysis of composite st eel girder highway bridges. The procedure uses a modified grillage (grid) a nalysis method where material nonlinearity is modeled by empirically derive d moment-curvature relationships. These are obtained from experimental data on the behavior of typical composite steel girder bridges. A linear variat ion of plastic curvature along the length of each beam element is assumed. An equivalent grid plastic hinge length, L-gp, is used to simulate the exte nt of plastification over the whole length of a grid element. The procedure can account for span continuity by including a negative bending moment-cur vature relationship. Numerical investigations verify the proposed method's validity by comparing the analytical results with those of in-situ and labo ratory full-scale and model-scale bridge tests. This paper also demonstrate s that the proposed nonlinear analysis method provides a simple tool that c an be used to obtain reasonably accurate representations of the nonlinear b ehavior of composite steel girder bridges. The method uses a grillage discr etization technique whose results are relatively insensitive to variations in the mesh size. The proposed method has a high potential for use in engin eering practice because of the simple input requirements and its reasonable level of accuracy.