Punching Strength of Reinforced Concrete Footings

A total of 17 reinforced concrete footings were tested to investigate the punching shear behavior of footings. The test parameters investigated are the shear span-depth ratio (a/d), concrete strength, and punching shear reinforcement. The (a/d) ranged between 1.25 and 2.0, whereas the concrete strength ranged between 20 and 40 MPa (2.9 and 5.8 ksi). To study the effect of soil-structure interaction, five footings were realistically supported on sand. The remaining specimens were supported on a column stub and a uniform surface load was applied. The present experimental investigations indicated that the angle of the failure shear crack is steeper in punching tests on compact footings than observed in tests on more slender slabs. Furthermore, the (a/d) significantly affects the punching shear capacity. Based on the test results, the ACI and Eurocode 2 provisions are critically reviewed and improvements are proposed. [PUBLICATION ABSTRACT]