Interaction of life-cycle phases in a probabilistic life-cycle framework for civil infrastructure system sustainability

Infrastructure system sustainability is dependent on contributions from different life-cycle phases like construction, operation, maintenance, failure and end-of-life demolition. While existing life-cycle studies typically consider many of these phases, the life-cycle sustainability is often expressed in terms of an expected value or variance. Moreover, interactions between life-cycle phases such as maintenance and service load or hazard failure are often neglected. The proposed probabilistic life-cycle sustainability analysis (LCS-A) framework captures phase interactions and explores the distribution of sustainability costs to provide a more holistic view of an infrastructure's LCS. The model is capable of handling various sources of uncertainties, with propagation of uncertainties facilitated by use of surrogate models when predicting infrastructure failure with phase interactions. A demonstration of the probabilistic LCS framework for a concrete girder bridge highlights the importance of looking beyond expected values of life-cycle metrics, especially when interactions between life-cycle phases are considered. maintenance activities primarily benefit service load performance, they also enhance hazard performance, a previously unexplored interaction effect from life-cycle studies.