Life Cycle Performance Metrics for Aging and Seismically Vulnerable Bridges

Bridge infrastructure faces both continued aging and deterioration throughout its lifetime, as well as potential exposure to natural hazards such as earthquakes in hazard prone regions. Consequential damage requires increased monetary investments, energy spent on subsequent repair/replacement, as well as carbon dioxide (CO2) emissions associated with the manufacture/transport of repair materials. This paper will derive and compare estimates of three important metrics associated with the life cycle performance of aging bridges given seismic exposure, namely, life cycle cost, embodied energy and associated CO2 emissions. A case study is presented for a representative multi-span simply supported (MSSS) concrete girder bridge to evaluate the life cycle sustainability metrics of the corroded bridge system given uncertain performance and repair under lifetime exposure to seismic hazards. The results underscore the importance of capturing the effects of time dependent structural deterioration when conducting life cycle analysis of bridges based on different indicators. The proposed framework is also anticipated to help guide the selection of optimal rehabilitation or retrofit measures for bridge infrastructure based on target sustainability metrics related to life cycle cost, energy usage, and harmful emissions.