Behaviour of soil-steel composite bridge with various cover depths under seismic excitation

The design codes and calculation methods related to soil–steel composite bridges and culverts only specify the minimum soil cover depth. This value is connected with the bridge span and shell height. In the case of static and dynamic loads (like passing vehicles), such approach seems to be quite reasonable. However, it is important to know how the soil cover depth affects the behaviour of soil–steel composite bridges under seismic excitation. This paper presents the results of a numerical study of soil–steel bridges with different soil cover depths (1.00, 2.00, 2.40, 3.00, 4.00, 5.00, 6.00 and 7.00 m) under seismic excitation. In addition, the same soil cover depths with different boundary conditions of the soil–steel bridge were analysed. The analysed bridge has two closed pipe-arches in its cross section. The load-carrying structure was constructed as two shells assembled from corrugated steel plate sheets, designed with a depth of 0.05 m, pitch of 0.15 m, and plate thickness of 0.003 m. The shell span is 4.40 m, and the shell height is 2.80 m. Numerical analysis was conducted using the DIANA programme based on the finite element method. A nonlinear model with El Centro records and the time history method was used to analyse the problem.