Seismic behaviour of continuous composite bridges with abutment restraints

The performance of multi-span steel-concrete composite bridges in recent seismic events has shown that these structures are very sensitive to earthquake loading. In order to reduce deck bending and to avoid expensive bi-directional joints, a rigid connection can be realized between the deck and the abutments, so that the inertia forces are resisted not only by the piers, which are expected to yield in order to dissipate energy, but also by the deck-abutment system. In these situation, the sequential yielding of the piers may cause a substantial change of the stiffness and force distribution among the bridge components. The objective of this paper is to assess the influence of piers-deck stiffness ratio in the seismic behavior of continuous composite bridges with dual load path and to evaluate the suitability of simplified linear elastic analysis in estimating the actual structural behavior. Parametric analysis results are presented for a common bridge typology.