Higher order model for the seismic response of bridge embankments

The paper presents a new higher order model for the dynamic analysis of embankments. By considering a Legendre polynomial expansion to describe the motion at a generic point of the embankment, the application of the Lagrange-D'Alembert principle in conjunction with a through-the-width closed-form integration allows reducing the 3D physical domain into a 2D analytical domain. 4-node isoparametric elements with linear interpolating functions are used to numerically solve the problem. The model is suitable for bridge embankments by introducing a kinematic rigid constraint to account for the presence of the abutment. The embankment frequency dependent impedances and the displacements to be imposed to the abutment in bridge seismic analyses are obtained by condensation. The model has been validated comparing results with those furnished by high-fidelity 3D finite element models. The application to the approach embankment of an instrumented bridge subjected to a severe earthquake has demonstrated the model capability to capture both occurrence and intensity of main response peaks, as well as the frequency content of the response.