SHEAR CAPACITY OF CONTINUOUS RC BEAMS WITHOUT SHEAR REINFORCEMENT

Beams or one-way slabs are often continuously supported and slabs are mostly not shear reinforced. In a continuous beam the transition from hogging moment to sagging moment influences the development of diagonal shear cracks. As a consequence, the shear capacity of a continuous member is expected to different from a simply supported member with the same a/d ratio. However, this is not revealed in the Dutch design code. The influence of the moment distribution on the shear capacity of continuous beams has been investigated in this paper. To that end a series of experiments on cantilevered simply supported beams were carried out at Delft University of Technology. Two point loads were applied; one at the cantilever end and one along the span with a certain shear span a. By controlling these loads the ratio between the hogging moment at the support (M-) and the sagging moment in the span (M+) was kept constant. The main variables in this study are MIME and a/d. In this paper the experiments and the phenomena observed are described and recommendations are given to the design practice.