End patch loading behavior and strengthening of locally corroded steel I-beams

One of the problems that affect steel bridges is the deterioration of the beam ends due to local corrosion, thus reducing their end patch loading resistances. A recent paper by the authors has studied the individual influences of web and flange corrosions on the end patch loading behavior of steel I-beams. This paper presents further experimental results for the specimens with combined web and flange corrosions, since they coexisted in many cases. Two common types of sliding plate bearings were considered in this study, i.e., flat and curved plate bearings. The test results show that the end patch loading resistances of the specimens with flat plate bearings are higher than those of the corresponding specimens with curved plate bearings, especially for the corroded beams. With regard to the specimens with flat plate bearings, the combined effect of web and flange corrosions on the end patch loading resistance is less than the sum of the effects of each alone. In addition, a novel strengthening method is developed for the steel beams affected with severe local corrosion. The corroded beam end is first strengthened by welding a pair of stiffeners and is then partially encased with high-strength grout. It is found that the end patch loading resistance of the corroded beam can be significantly increased by the stiffeners and can be further enhanced with the encasement of high-strength grout. The proposed method can minimize the traffic interruption and also prevent the bottom of the beam ends from secondary corrosion.