Field Monitoring and Numerical Investigation of Integral Abutment Bridges with Tied Approach Slabs

Abstract Integral abutment bridges provide a monolithic connection between the superstructure and the substructure. They can be paired with tied approach slabs, which eliminate expansion joints at bridge ends, helping mitigate some of bridge end deterioration issues. Because of fixities introduced at bridge ends, the complex behavior of bridge structures that include integral abutments and tied approach slabs is not yet fully understood, leaving questions regarding the adequacy of current design details. To address this research gap, the presented study systematically investigated the structural response of a set of integral abutment bridges with tied approach slabs under service loads. For this purpose, field monitoring, numerical analysis, and design evaluation were conducted. To obtain real-world performance data, two bridge ends were instrumented to measure movements, strains, and stresses developed in the rebars embedded in the approach slabs. Validated finite-element models were then used to investigate various structural performance measures, particularly in response to a range of void-formation scenarios expected in the embankment. The numerical analysis was further expanded to study approach slab settlement in the absence of sleeper slab supports. A supplementary numerical study was subsequently conducted to investigate design variables, including slab–soil coefficient of friction, approach slab–sleeper slab coefficient of friction, soil stiffness, tie bar orientation, and skew angle. Results indicated that temperature effects govern structural demands, with significant stress concentrations at skewed bridge corners. Increased soil stiffness and friction amplified stresses, while inclined tie bars improved force transfer. The outcome provided original insights and recommendations to improve the design and construction of integral abutment bridges with tied approach slabs.