TYPOLOGICAL FRAGILITY ASSESSMENT OF PRESTRESSED CONCRETE GIRDER BRIDGES SUBJECTED TO TRAFFIC LOADS AFFECTED BY CORROSION

Most of the Italian roadway bridges, built from 60s to 80s, are simply supported, girder-type, prestressed concrete bridges. After at least 50 years of service life, material degradation and functional obsolescence problems are coming out leading to the need for evaluating bridge vulnerability to natural and anthropic hazards. Particularly, this study aims at investigating the structural response to traffic loads of different typologies belonging to this bridge class. In this study, geometric and material random variables are assumed to simulate inter-class property variability and statistical sampling techniques are used to randomly generate bridge realisation for each investigated bridge typology. A simplified traffic load analysis is performed, subjecting each bridge realisation to various traffic load models (TLMs) proposed by the current Italian building code. Particularly, different post-tensioned tendon corrosion scenarios are assumed, evaluating the variation in response. Fragility curves are built for each bridge typology for each corrosion scenario and results are discussed with a view to prioritisation in the large-scale assessment of existing prestressed concrete bridge class.