Flexural responses of concrete slab over flexible girders through FEA-based parametric evaluation

The determination of flexural responses in a concrete slab over flexible steel girder, forming a composite deck has been a timeconsuming subject for the design engineers. The existing provisions of the design standards such as AASHTO or analytical solutions based on local bending or plate theory usually ignore some significant parameters affecting the deck response, such as girder flexibility, number of loaded traffic lanes and ratio between deck width and girder span. This may lead to unrealistic prediction of bridge flexural responses used in the slab design practice. Although it is well known that finite element analysis is very versatile for structural analysis, very few studies have been reported dealing with explicit determination of deck slab response. The present study investigates the transverse negative bending moment of the slab cast over a number of steel girders, subjected to traffic loads, using verified composite Shell-Frame and Plate-Frame Models. The evaluation of such response is carried out through an extensive parametric study focusing on the effect of girder flexibility due to patterns of moving loads. Based on the numerical results, empirical relationships are proposed to determine the maximum slab moments anywhere along the girder span. The application of these relationships is then compared with other references. The suggested relationships seem to give more realistic and economical values of the considered transverse slab bending moment for a wide range of deck proportions.