Dynamic modelling of bridge approach slabs under moving loads

Differential settlement is a common problem in the bridge-roadway transition zone. Approach slabs are often constructed to mitigate the uneven settlement in this problematic zone. An appropriate simulation of the dynamic response of moving loads, approach slab and soil materials is necessary for realistic results. In the present study, the performance of the slab under traffic flow is investigated by a 3D dynamic analysis. For this purpose, the slab is modelled as a plate element while Mohr-Coulomb material model is adopted for base, subbase and subgrade soils. A number of parameters were considered to study the sensitivity of the proposed model to some soil, slab and moving load parameters that contribute to the behaviour of the approach slab. The main variables investigated in this study were the slab thickness, the restriction condition of the slab, the subgrade stiffness, weight of the passing vehicles and the analysis method adopted in such problems. Analysis results including predicted deformations and slab bending moments provide engineers with the necessary engineering knowledge to understand the response of approach slabs under different conditions.