Life-cycle sustainability of highway bridges

Civil infrastructure is an integral part of society and comprises many existing publicly owned assets. In the modern world, highway infrastructure systems play a critical role in facilitating the mobility of people and goods. Therefore, it is extremely important to accurately assess and predict the performance of highway bridges. Comprehensive risk and sustainability assessment procedures are crucial in evaluating and ultimately mitigating detrimental consequences of structural failure to the economy, society, and the environment. The sustainability-based maintenance optimization decision-support framework proposed herein provides decision makers with optimal life-cycle maintenance actions that balance conflicting cost and performance objectives. Utility theory is employed in order to effectively capture the sustainability performance of highway bridges and impact of the decision maker’s risk attitude. The utility-based sustainability performance metric depends on three risk attributes (i.e., economic, social, and environmental risks), quantified with different units. Within this approach, the desirability of each alternative (i.e., maintenance plan detailing component replacement(s) and timing of intervention(s)) is quantified in terms of utility, a normalized metric bounded between 0 and 1. Multi-criteria optimization procedures based on sustainability objectives are employed in order to determine optimum lifetime maintenance strategies for existing bridges.