Influence of Support Conditions on Shear in RC Members Without Shear Reinforcement

Abstract

The present rules for shear design of reinforced concrete (RC) members without shear reinforcement according to Eurocode 2 are semi-empirical. The underlying database to calibrate the shear design approach comprises test data of more than 600 simply supported beams. In reality, various other support conditions occur, for instance in continuous beams. In that case, the moment-shear ratio in the member differs compared to simply supported beams. This influence is not considered in the shear design according to Eurocode 2. However, alternative design approaches, such as those according to Model Code 2010 or SIA 262, allow for the influence of the moment. In order to investigate the influence of the support conditions on the shear resistance, numerous shear tests on continuous members without shear reinforcement are carried out at the Institute of Structural Concrete at RWTH Aachen University. Full scale beams with a height of 0.28 m, a width of 0.3 to 0.5 m and a span of 3 to 4 m are tested under concentrated loads. The specimens are simply supported at one side and continuous at the other with varying levels of the hogging moment. As a result, the point of infection (P.I.) is varied. Also, simply supported reference tests are carried out. Further investigated influences are the distance from the load to the support, the longitudinal reinforcement ratio and the size of the load area. The experimental shear capacities are compared to the calculated shear capacities according to the presented design approaches to assess the influence of the moment-shear ratio. Possible modifications concerning the shear design for reinforced concrete continuous members without shear reinforcement are presented.