Research Activities: 2007
Project 2a: Reliability-based Evaluation of Bridge Components for Consistent Safety Margins - UMC | |||||||||
Status |
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Sequential Number | R239 | ||||||||
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Matching Research Agency | Missouri Department of Transportation (MoDOT) and University of Missouri - Columbia (UMC) | ||||||||
Principal Investigator |
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Student Involvement | One graduate and up to two undergraduate students per year. | ||||||||
Project Objective | The outcomes of this project are a reduction in the up-front cost of bridges and a sound rationale on load factors and resistance factors for service limit state, which has been determined primarily based on engineering judgment. | ||||||||
Project Abstract | The MoDOT LRFD Bridge Design Guidelines (LRFD hereafter, MoDOT, 2007) is a slightly modified version of the AASHTO LRFD Design Specifications (AASHTO, 2001) that were mandated for use in new bridge designs starting October 1, 2007. Based on structural reliability methods, the LRFD introduces a limit state design philosophy to achieve a more uniform level of safety (reliability) in new bridge design. In current practice, however, some bridge components are still designed to have different levels of safety from others due to 1) design of some bridge components are controlled by service limit state rather than strength limit state, 2) load factors for service limit state in LRFD is not well-calibrated with quantitative basis and consensus, 3) the service limit highly depends on traffic demand of a specific state. The objective of this project is to calibrate load and resistance factors in LRFD (MoDOT, 2007) to achieve a more uniform level of safety (reliability) in bridge design. The calibration of the load and resistance factors, specifically considering Missouri environment, will lead to a reduction in the up-front cost of bridges. Load factors will be calibrated to achieve two goals: 1) the bridge components should have consistent safety margin, and 2) the bridge components designed with LRFD should be compatible with components designed with LFD which have performed well for the past years. The scope of the proposed project is: • To develop service load models and to establish service limit state criteria for Missouri condition and environment based on the past maintenance records • To calibrate the LRFD Bridge Design Guidelines (MoDOT, 2007) and to identify over-conservatively designed bridge components for overall cost reduction • To develop necessary revisions of MoDOT Standard Plans for Highway Construction for typical types of MoDOT bridges to reflect the LRFD design philosophy The outcomes of this project are a reduction in the up-front cost of bridges and a sound rationale on load factors and resistance factors for service limit state, which has been determined primarily based on engineering judgment. | ||||||||
Task Description | N/A | ||||||||
Anticipated Benefits | Reduction in up-front bridge costs. | ||||||||
Milestones |
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Relationship to other Research/Projects | Works with same project out of Missouri S&T. | ||||||||
Technology Transfer Activities | Publications engineering journal. | ||||||||
Transportation Research Board Keywords | Reliability, Bridge Design, AASHTO, LRFD | ||||||||