Reliability Based Structural System Performance Indicators for Highway Bridges

摘要

The current AASHTO LRFD highway bridge design specifications have been calibrated with the stated goal of achieving uniform reliability levels for all bridge configurations, components, and material types for a 75-year design life. Although this goal has been met for checking the strength and fatigue limit states of main bridge members under the effect of live loads, several criteria for other limit states and hazards were simply adopted from previous generations of design codes while other extreme event limit states were developed using different probabilistic bases than those used for the live load effects. This paper presents an overview of current code-specified criteria for evaluating the performance of bridge systems under various types of hazards, summarizes ongoing studies to extend the reliability-based calibration to new types of members and components and outlines remaining issues that should be addressed in order to develop criteria that will achieve consistent levels of bridge system safety and reliability.