Vulnerability Analysis and Risk Assessment of GA Bridges under Fire
Dr. Rami Haj-Ali, Georgia Tech, 404-894-4716, rami.haj-ali@ce.gatech.edu
Objectives and Approach
ˇ Generate structural analysis and assessment tools for normal-concrete (NC), high performance concrete (HPC) and steel girder bridges under high temperature loadings due to fire.
ˇ Develop three-dimensional combined fire-structural analysis along with refined and realistic 3D simulations of bridges at elevated temperatures.
ˇ Investigate the current fire design practices for NC, HPC and steel structural components.
ˇ Investigate different fire resistance strategies for damage mitigation.
Summary
A three-dimensional (3D) combined fire-structural analysis and simulations approach is proposed for NC, HPC and steel girder bridges. New fire-dynamic simulations (FDS) are proposed for realistic bridges with 3D fire scenarios including fire trucks accidents. Approaches for temporal-spatial approximation of elevated temperatures are investigated in order to effectively represent the spatial history of the temperature profiles from the FDS models. The proposed 3D FDS and structural modeling framework allows investigating the response of NC, HPC and steel components and predict their time-to-collapse. The project will examine various methods for in-place strengthening, repair, and upgrade of bridges that is previously damaged by fire or high temperature loads.
Examples:
Hypothetical Fire-Scenario due
to a Fuel-Truck Accident under the 17th-street Bridge in Atlanta , GA
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Heat Release Rate During Fire |
17th-Street Bridge Geometry |
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Temperature History During
Fire |
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Fire-Simulation of the Fuel-Truck Accident under the Oakland I-580 Steel Bridge over I-880, CA (April 29, 2007)
A gasoline tanker crashed and burst into flames near the San Francisco-Oakland Bay Bridge on Sunday (April 29, 2007) at 3:41am. Because of the heat from fire, one of I-580 Highway Bridge was collapsed. The accident started at 3:41am and the bridge collapsed at 4:02am. A total of 8600 gallons of gasoline was spilled and burned. Below, we present our simulations and temperature predictions of the steel girders. The predicted temperature levels (around 1000 ēC) match the damaged zone shown of the bridge at collapse time.
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Oakland I-580 Bridge over
I-880 |
Collapsed bridge |
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Heat Release Rate from Simulations |
Video taken of the fire (PBS-news) |
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Temperature History During Fire |
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Real and Hypothetical Fire-Simulations of Fuel-Truck Accidents on/under the I-285 Bridge over GA400 north (In progress)
Case-1: A fuel truck hit the I-285 barrier and spilled more than 1000 gallons of gasoline on June 9, 2001. After the accident, Georgia Department Of Transportation(GDOT) replaced damaged part of the bridge.
Case-2: In progress scenarios are currently being investigated
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I-285 Bridge Geometry |
I-285 under the Bridge Geometry |
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Temperature History During Fire |
Heat Release
Rate During Fire |
