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The punching shear design procedures according to current codes (e.g., Eurocode 2 or Model Code 2010) are similar. However, the predicted punching shear capacities may differ significantly depending on the background (e.g., semi‐empirical or physical) of the design provisions and the considered influences. For the evaluation and improvement of the existing provisions for flat slabs without and with high amounts of shear reinforcement, a large number of punching test series on reinforced concrete flat slabs is available in the literature. 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 only few punching tests on flat slabs with low and medium amounts of shear reinforcement have been conducted. To investigate the punching shear behavior of flat slabs with a varying amount of shear reinforcement, three systematic test series without and with stirrups as shear reinforcement were conducted. The experimental program included three reference tests without and eight tests with low and medium amounts of shear reinforcement. 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. 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. [ABSTRACT FROM AUTHOR]

Punching strength of flat slabs with varying shear reinforcement ratios With the introduction of Eurocode 2 in Germany, the punching shear design provisions of flat slabs were revised. Since then, the punching shear strength with shear reinforcement is calculated from the combination of a constant concrete contribution and a steel contribution, which results from a strut inclination of 33°. Besides, a reduced steel strength depending on the effective depth of the flat slab is assumed for the calculation of the steel contribution to consider the anchorage conditions of the shear reinforcement elements. Due to a database analysis and an evaluation of the level of safety compared to the former DIN 1045‐1, additional factors have been implemented in German Annex to Eurocode 2 (EC2+NA(D)) for the first and second row of shear reinforcement leading to almost twice the amount of required shear reinforcement. Various test series on reinforced concrete flat slabs without shear reinforcement and with high amounts of shear reinforcement are available and can be used for the evaluation 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 only very few systematic punching tests with a varying amount of shear reinforcement have been conducted. To investigate the punching shear behavior of reinforced concrete flat slabs with stirrups as shear reinforcement, three systematic test series (eleven specimens) with varying shear reinforcement ratios were performed. Each test series included one reference test without shear reinforcement. In the tests, the shear reinforcement ratio 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 tests are presented, discussed and compared to the predictions according to Eurocode 2 and EC2+NA(D). Moreover, the punching design provisions according to Model Code 2010 are evaluated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Due to a smaller shear span-depth ratio and soil-structure interaction, footings and ground slabs achieve significantly higher punching shear capacities than flat plates. Because the inclination of shear cracks is steeper in footings, punching shear reinforcement elements with inclined bars seem to be more efficient than vertical bars. On the basis of previous experimental investigations on footings with punching shear reinforcement, a new punching shear reinforcement element with inclined bars was developed. To evaluate the efficiency of the punching shear reinforcement element, seven tests on reinforced concrete footings with uniform soil pressure and a failure within the shear-reinforced zone were conducted. The tests were planned considering the results of a previous systematic test series on reinforced concrete footings without and with stirrups as punching shear reinforcement. The main parameters investigated in the present test series were the shear span-depth ratio, the ratio of column perimeter and effective depth, the number and layout of punching shear reinforcement elements, and the effect of longitudinal reinforcement at the compression side. The comparison of the results of the new test series with the previous test series proves a significant increase in punching shear capacity with the newly developed punching shear reinforcement. [ABSTRACT FROM AUTHOR]