Nonlinear analysis of RC box culverts resting on a linear elastic soil

In the analyses presented, the soil-structure interaction is accounted for by means of a FE-BIE approach, in which the structure is modelled with displacement-based beam finite elements, whereas the boundary between structure and substrate is described in terms of surface tractions by means of a boundary integral equation incorporating a suitable Green's function. This mixed formulation ensures full continuity between structure and substrate in terms of displacements and rotations. To take account of structural nonlinearities, potential plastic hinges are defined at the end sections of the beam elements in the form of semi-rigid connections characterized by a rigidplastic moment-rotation relationship. The incremental analyses carried out emphasize the effectiveness of the model in reproducing collapse mechanisms and stiffness loss of the structure for increasing loads. Moreover, the adopted formulation is able to capture both interfacial shear tractions and vertical normal tractions which develop along the substrate boundary under a variety of loading conditions.