Houston, TX 77005
1:00 p.m. Monday, April 8, 2013
Health | Wellness,
The highway bridge infrastructure system within the United States is rapidly deteriorating and a significant percentage of these bridges are approaching the end of their useful service life. Natural hazards, such as earthquakes, further threaten the safety and security of these critical civil structures. This research aims to offer an efficient framework for accurate assessment of seismic reliabilities of aging highway bridges. Nonlinear dynamic analysis of 3-dimensional high-fidelity finite element bridge models are used to assess the impact of aging mechanisms on bridge component responses, considering chemical deterioration as well as degradation from repeated seismic shocks. Subsequently, time-dependent fragility curves are developed at the bridge component and system level to assess the probability of structural damage given earthquake intensity. In addition to highlighting the importance of accounting for deterioration mechanisms, these time-evolving fragility curves are used within an improved seismic loss estimation methodology to aid bridge owners and stakeholders with risk mitigation decisions. Further, statistical learning methods are employed to derive parameterized fragility models conditioned on earthquake hazard intensity, bridge design parameters, and deterioration affected structural parameters to provide significant improvements over traditional fragility models and aid in efficient estimation of aging bridge vulnerabilities. Given their importance for bridge management decision making, a framework is presented to demonstrate the updating of aging bridge reliabilities with field-measurement data across a transportation network. Finally, this research also proposes a joint live load and seismic fragility framework to assess the impact of truck traffic loads on the seismic vulnerability of highway bridges and offer guidance to risk analysts regarding the comparative importance of considering simultaneous live loads and earthquake hazards.