Seismic reliability of Italian code-conforming bridges

Seismic reliability assessment of selected bridge structures code-conformingwith respect to the current Italian practice is carried out. Two viaducts, talland shallow, and two highway overpasses, with traditional seat-type or integralabutments, are considered. Each structure is ideally placed at three referencesites, that is, Milan, Naples and L’Aquila, characterised by low, moderate andhigh seismic hazard, respectively. At each site, a soil profile representative oftypical local conditions is defined for foundation design, site response anal-ysis and soil-structure interaction modelling. Probabilistic seismic hazard isused in conjunction with multiple-stripe non-linear dynamic analysis, featur-ing conditional-spectrum compatible ground motions, to establish the failureratewithrespecttotwopurposelydefinedandfunctionality-relatedperformancelevels. It is confirmed the decreasing seismic reliability with increasing designseismic action, already observed for other structural types, and it is shown thatintegral abutment overpasses tend to be more reliable than traditional ones, evenseismically isolated ones. The results are of larger interest given the closeness ofthe Italian code to the Eurocode.