Rehabilitation performance of welded joints in aged railway bridges

A strengthening method for welded joints in aged steel railway bridges using Glass Fiber Reinforced Plastic (GFRP) plates, rubber-latex mortar, and rapid hardening concrete and reinforcing bars is introduced in this paper. The purpose of the present study is to investigate the performance of the welded joints before and after strengthening. Totally two joints, designed to sustain positive and negative bending moment respectively, were used in the experimental study. The static loading tests were performed to confirm the effects of the present strengthening method. Moreover, three-dimensional FE models were built to make a numerical study on the present strengthening method. Load versus deflection relationship and sectional strain distribution were measured and compared between the original joints and the strengthened joints. Both experimental and numerical results indicate that the present strengthening method can greatly enhance the stiffness and reduce the stress levels of the welded joints, resulting in the extension service life of old railway bridges. Besides, influence of bond strength was investigated, and the effect of the rubber-latex mortar was confirmed.