JTRP Technical Reports

Final report.PDFTech ReportFHWA/IN/JTRP-2012/13SPR-3474Environmental impactsFiresSteel bridgesGirdersLoad testsFatigue (Mechanics)IndianaPurdue University. Joint Transportation Research ProgramBradt, Thomas G.Rankin, BrentConnor, Robert J.Varma, Amit H.Purdue University. Joint Transportation Research ProgramIndiana. Dept. of TransportationUnited States. Federal Highway AdministrationNTL-ENERGY AND ENVIRONMENT-Environment ImpactsNTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and StructuresUS Transportation CollectionCurrently, when a bridge has been involved in a fire loading, DOT and inspectors are called to determine if the bridge is passable totraffic. Inspectors must close the bridge for an indefinite period of time to take material samples from the bridge and have them testedto find if the strength of the materials meets AASHTO specifications. This procedure can take time and severely impact the economy ofsurrounding municipalities due to bridge closure. When a bridge is visually distorted, the recommendations of what must be done torepair the bridge may be intuitive; but when no apparent deformations are visible, a way of inspecting the bridge should be uniform andeasily performed. The implementation of the findings of this report and the included inspection guide will provide inspectors a generalidea of the changes in material properties of the bridge steel, based on the visual appearance of the steel.A method of testing has been developed that allows researchers to take flange and web sections from a bridge girder and test them inreal fire scenarios. The test setup allows researchers to examine the differences in outcomes due to a variety of paint coatings on thesteel, thickness of steel, temperature and duration of fire exposure. After each different test, material properties may be determinedand compared to virgin or unexposed steel and AASHTO specifications to see if the material properties have changed or if the material isbelow minimum standards. Each specific test is photographed at certain stages that would be seen at a bridge in the field after beinginvolved in a fire. These photographs can then be compared to actual bridge damage and an estimate of surface temperature could beattained. The inspection guide would then give average values for the reduction or increase of tensile strength and toughness for aparticular bridge