THE DEVELOPMENT OF MULTIHAZARD DESIGN GUIDES FOR HIGHWAY BRIDGES

摘要

The American Association of State Highway and Transportation Officials (AASHTO) Load andResistance Factor Design (LRFD) Specification for bridges have its strength design limit stateformulated and fully calibrated using the reliability-based approach. The extreme event designlimit states, however, are constructed by combining the non-extreme load effects with theindependently established extreme hazard load effects through professional judgment. Its marginof safety and adequacy could not be assessed quantitatively. A research project sponsored by theFederal Highway Administration (FHWA) has been carried out to explore principles andapproaches for establishing multiple-hazard (MH)-LRFD based on the established rationale andreliability-based methodology of the AASHTO LRFD. An analytical framework has beenestablished to consider the non-extreme and extreme loads on a common reliability-basedplatform. This paper describes the formulation of specific extreme event design limit state (e.g.the limit state for non-extreme load with the earthquake load effects) by using the all-hazard,reliability-based approach. Future challenges towards the development of a comprehensive MHLRFDare also described.