Punching shear behavior of reinforced concrete footings with a varying amount of shear reinforcement

The existing punching shear design provisions according to current codes have either a semi-empirical (e.g., Eurocode 2) or a more physical (e.g., Model Code 2010) background. Although the design procedures are very similar, the predicted punching shear capacities may differ significantly, depending on the background of the design provisions and the considered influences. Recent test series on reinforced concrete footings without shear reinforcement and with high amounts of shear reinforcement are available and can be used for the evaluation and improvement of the current provisions. Nevertheless, the evaluation of the code equations for the design of the shear reinforcement (failure inside the shear-reinforced zone) is still not possible since systematic test series on footings with a varying amount of shear reinforcement have not yet been conducted. To investigate the punching shear behavior of reinforced concrete footings with low and medium amounts of shear reinforcement, three systematic test series (11 specimens) with stirrups as shear reinforcement were conducted. In the tests, the amount of shear reinforcement was varied by changing the stirrup diameter only. Further investigated influences were the shear span-depth ratio and the effective depth. In this paper, the results of the test series are discussed and compared to the predictions according to Eurocode 2, Model Code 2010, and the draft of the second generation of Eurocode 2.