Corrosion of steel is a worldwide issue which potentially affects structural integrity of bridges. This research presents the results of comprehensive lab tests on the stress effect on corrosion and the combined effect of stress and corrosion on the mechanical properties of steel bridge elements. G250 mild steel specimens, commonly used for bridge construction, are used for analysis. Both stressed and non-stressed specimens are immersed in acid solutions to simulate corrosion progress. The stress effect on corrosion rate (mass loss) is studied. The combined effect of stress and corrosion on mechanical properties is also studied. Hydrogen concentration is monitored for stressed and non-stressed steel during corrosion to find the mechanism of the degradation of mechanical properties. The outcome of this research can help bridge engineers and asset managers to better model corrosion and more accurately assess the structural integrity of corrosion affected steel bridges.