In situ evaluation of strengthening methods for reinforced concrete T-beam bridge

The structural integrity of reinforced concrete (RC) bridges is critical to the safety and functionality of transportation infrastructure. This paper presents a field investigation of steel-based strengthening methods for rehabilitating deteriorated RC T-beam bridges, encompassing transverse, shear, and flexural enhancements. Static load testing using four dump trucks was conducted to evaluate the performance of strengthening methods. Finite element (FE) models were developed to analyze structural behavior and complement the experimental investigation. The results show that the transverse strengthening successfully improved transverse load distribution across the beams. A detailed investigation was conducted on three flexural strengthening methods designed to reduce deflection. The steel channel strengthening (SCS) method proved to be the most effective in improving stiffness of the beams, compared to the cover plate strengthening (CPS) and the steel truss strengthening (STS) methods. The SCS method reduced the maximum mid-span deflection by up to 50.7% compared with the unreinforced condition, outperforming the CPS (17.5%) and SCS (19.5%) methods. Strain distribution analysis confirmed effective composite action for the CPS and SCS approaches, whereas the STS method exhibited incomplete composite behavior. The results highlight that achieving effective composite behavior between the strengthening system and the existing concrete member is a governing factor for strengthening performance. Parameter analysis demonstrates that the 16B channel used in SCS practical application provides a cost-effective option. The findings validate the steel-based strengthening methods for deteriorated RC bridges and provide practical guidance for field applications.