Seismic wave effects on the dynamic response of bridge foundations

The dynamic response of structures to earthquake loading depends mainly on: the characteristics of the incident seismic waves; local site conditions, such as topographic irregularities and heterogeneity of the soils; the presence of stiff and heavy embedded foundations; the deformability of the soil supporting the structures. These phenomena can be relevant for bridges that usually have deep foundations and extent over considerable distances. In this paper the dynamic response of a bridge pier subjected to polarized shear waves is investigated. Different wave patterns are considered and the corresponding free-field ground motion is calculated with reference to a linear elastic halfspace. The pier is founded on a rigid caisson and soil-structure interaction is solved using the Winkler type model developed by Gerolymos and Gazetas.