Effect of horizontal web reinforcement, depth, proportionated loading and bearing plates on shear strength and serviceability of reinforced concrete deep beams

In this paper, the strength, serviceability and failure modes of eleven reinforced concrete (RC) deep beams were evaluated. The small, medium and large-size specimens with heights ranging from 300 to 1250 mm and effective spans from 600 to 2500 mm were tested up to failure under the three-point bending test. The length of loading and bearing plates varied from 100 to 400 mm, and the percentage of horizontal web reinforcement varied between 0.00 % and 0.45 %. Test results revealed that distributed web reinforcement and proportionate loading and supporting plates mitigate the size effect. Further, when the percentage of horizontal shear reinforcement increased, the mode of failure changed from diagonal tension to shear compression. From the test results, it has been concluded that the optimum horizontal web reinforcement was 0.25 % for achieving the highest ultimate and service load. The strength reduction factor of maximum shear force expression of ACI 318–19 [25] code adequate even in the case of deep beams failing in shear compression mode is experimentally validated.