Integral abutment bridge concept applied to the rehabilitation of a simply supported concrete structure

A case study aiming to transform a simply supported pre-stressed concrete flyover into a frame structure throughout its full length, through refurbishment, is presented. Hogging moment resistance is achieved at the piers by the construction of a rigid transverse cast-in-place concrete diaphragm connected to the piers and to the beams of adjacent bays, in an attempt to fulfil the requirements of the integral abutment bridge (IAB) concept specified. All former bearings and expansion joints are eliminated resulting in an improved durability of the structure and greater comfort for the users. According to the IAB concept, hogging moment resistance is obtained by the flow of tensile forces through the concrete slab thanks to an increased ratio of reinforcement and the transmission of compressive forces directly through the concrete. Shear transmission is ensured by the installation of a convenient number of concrete-to-concrete shear studs on the webs of each of the beams forming the deck. Experimental tests were used to investigate the behaviour of shear studs. The possibility of making a simply supported deck continuous for a certain length depends on the soil-structure interaction and, consequently, on a wide number of parameters, varying from case to case, that will not be investigated in the present paper.