MULTI-CRITERIA COMPARATIVE ASSESSMENT OF SEISMIC RETROFITTING INTERVENTIONS OF AN OVERPASS RC BRIDGE CONSIDERING ENVIRONMENTAL IMPACT

Bridges are essential to transportation infrastructure and society as a whole, as their failure can result in fatalities, business disruptions (e.g., traffic delays), and hinder rescue operations. The deteriorating condition of many bridges, evidenced by recent failures worldwide, highlights the urgent need for their assessment, retrofitting, or replacement. Various strengthening solutions exist to meet seismic capacity as per code-based requirements. However, selecting the most appropriate intervention requires evaluating not only structural criteria but also multiple decision variables (DVs) that also account for societal demands. Multi-criteria decision-making (MCDM) methods can be used to optimise these choices by considering economic, social, and technical factors. However, environmental impact (EI) is often overlooked in retrofit decisions in bridges. This study investigates the seismic response of a case-study bridge in northern Italy, both in its as-built condition and under various retrofitted configurations. Four retrofitting strategies, designed using standard engineering practice, are assessed through non-linear dynamic analyses to evaluate their overall performance and expected losses through the PEER-PBEE framework. To quantify EI, an environmentally extended input-output life cycle analysis is conducted. The retrofitting interventions are then comparatively evaluated using multiple decision matrices within the MCDM framework, considering 10 decision variables (DVs), including EI, which plays a significant role in the decision-making process. The results indicate that incorporating EI into the MCDM framework can influence the preference ranking of retrofit alternatives, which can assist engineers and decision-makers in evaluating and selecting optimal retrofit options for existing bridges.