In recent decades, bridge fires have become a major concern in the U.S. Fire hazard in bridges can result in significant economic and public losses. Traffic on fire damaged bridges is usually hard to detour and can significantly affect traffic quality in the region. Further, a severe fire may result in permanent damage or even collapse of the bridge. While the perception may be that it is unlikely that a bridge will collapse under fire, a recent nationwide survey by the NYDOT has shown that nearly three times more bridges have collapsed due to fire than earthquakes. New construction of bridges often use “Weathering Steel” (also known as “Corten Steel”), which has a corrosion-retarding effect since the steel forms a protective layer on its surface under the influence of the weather.  To date, no information exists on the effect of high temperature (heated and residual) on the mechanical properties of weathering steel.  This proposal will develop this knowledge. There are two important reasons to know the high temperature properties of bridge steels: (a) to make a rapid post-fire assessment of a steel girder; and (b) to make informed decisions for potential heat straightening of bridge overpasses that have been affected by fire or have been impacted by a vehicle that exceeds the vertical clearance.  This proposal is motivated by bridge fires, although the results can be applied to heat-straightening of impacted bridge girders as well.