Shear tests on full-scale bridge slabs with bent-up reinforcing bars

Abstract

Shear reinforcement design has changed over time, along with the knowledge about the shear behaviour of reinforced concrete structures. Until the 1970s, the shear design in Europe was based on empirical limits for shear stress. The rules stipulated by the design standards often resulted in designs of concrete slabs with shear reinforcement consisting only of bent-up bars without any additional stirrups. Today, truss models are widely used to design shear reinforcement. However, in the structural assessment of bridges with bent-up bars, it is difficult to apply such models due to their specific detailing requirements. In order to evaluate the applicability of current design standards and to span the knowledge gap between the load-bearing behaviour of small-size specimens and actual structures, four shear tests on two full-scale replica bridge slabs containing bent-up bars are presented in this paper. The applied load configuration represents two-axle and four-wheel loads of the current load models for railway bridges stipulated by Eurocode 1–2 and train load model UIC 71. The load distribution due to a track superstructure consisting of a track, sleepers and ballast was investigated. A comparison of the obtained results with those of preliminary tests on narrow slab strips shows differences in the load-bearing behaviour of small-format laboratory tests. The results of the analysis of the bridge slabs according to various design standards show the potential of the newly developed potential shear crack model for the assessment of slab bridges with bent-up reinforcing bars.