Effects of soil-structure interaction on direct displacement-based assessment procedure of multi-span reinforced concrete bridges

Abstract

This investigation deals with the relevance of non-linear dynamic soil-structure interaction (SSI) effects on the seismic assessment of single-column multi-span reinforced concrete bridges resting on rigid shallow foundations and non-liquefiable soil. The engineering motivation arises from the recent development of performance-based approaches, aiming at characterising the structural behaviour in terms of displacement, rotation, distortion and drift performance rather than in terms of strength criteria, and moreover, exploiting non-linear energy dissipation both at the superstructure and at the soil-foundation level. The need of an accurate, time efficient and readily implementable seismic assessment procedure is particularly important for bridges, which should still be functional after the earthquake for allowing the civil protection interventions and first aid organisations. Based on the framework of direct displacement-based seismic assessment procedure, a new iterative pseudo-static procedure (denoted as DDBA + SSI) satisfying these requirements is proposed. The predictions of both DDBA and DDBA + SSI procedures are compared to the results of incremental dynamic analyses for five hypothetical bridges. The salience influence of SSI effects on the seismic assessment is demonstrated.