Reliability and Risk Analysis of Bridge Networks Under the Effect of Highway Traffic Load

Over the last twenty years, the engineering community has realized the importance of developing design methodologies that explicitly considered concepts of risk management. Particular attention has been paid by structural engineers to extending the design concept from its original focus on a single structure such as a building or a bridge to a more complex approach that considers systems and networks of structures. Attention to risk management techniques was partially motivated by several recent extraordinarily devastating events. Recovery from these extraordinary events is agonizingly slow causing years of disruption to the local economy and causing major jolts to national economies. Major events impact the entire infrastructure system of the affected area highlighting the importance of managing the risk to infrastructure systems using multi-hazard methodologies at the "network" level rather than on an "item-by-item" basis.;In the U.S., a key element of the infrastructure system that has a major impact on the regional and national economy is the highway transportation system. Specifically, bridges which form key nodes of the highway network are especially vulnerable to various types of hazards. Even the closure of a single bridge can have major importance. For instance, it has been estimated by this study that the two-year closure of the Lake Champlain Bridge in New York State in 2009 weighted on the freight industry an additional cost of ;The objective of this research study is to reduce the gap between current research in risk analysis methods and the state of bridge engineering practice. The main goal is to develop techniques that are not too different from the current bridge design and evaluation techniques that are very familiar to practicing engineers and yet are adjusted to take into consideration the salient features of risk analysis and management principles. Along with this target the objective is to have engineers use data that are currently widely accessible through databases such as the National Bridge Inventory (NBI) files to adjust the load and resistance factors based on the specific risks that a particular bridge is exposed to. The focus of the study will be on the long term threats from overloads, repetitive loading and ageing processes which afflict most bridges in all parts of the U.S. However, the procedures could be in the future adapted to specific types of threats or to the multi-hazard risk analysis.