Seismic Vulnerability of R.C. Bridges Exposed to Corrosion

Recently, the engineering interest about the durability of existing reinforced concrete structures has significantly in- creased as confirmed by the conspicuous scientific literature. The results of these studies are influencing the development of new structural codes. Among the wide range of existing reinforced concrete structures, motorway viaducts stand out for their strategic relevance. Most of these structures were built between ’60 and ’70 years and, nowadays, the materials degradation phenomena are leading to strength capacity reduction, either in serviceability condition or in presence of exceptional loads such as the seismic ac- tion. In order to evaluate the degradation phenomena effects on the seismic vulnerability of motorway viaducts, this paper shows a new procedure to evaluate the seismic performance of reinforced concrete bridges starting from the modelling of the materials deg- radation - according to several scenarios - and by carrying out multimodal pushover analyses. The degradation is considered in terms of reduction of the concrete cross-section and steel rebar area. The results give an accurate estimation of seismic performance in terms of seismic vulnerability index variation and consequent management activities (e.g. planning and execution of rehab works).