New Punching Shear Reinforcement System for Footings and Ground Slabs

Punching shear tests on footings indicated that the inclination of compression struts is much steeper compared to flat slabs. The resulting steeper inclination of shear cracks leads to the assumption that vertically arranged punching shear reinforcement elements are less efficient in footings than in flat slabs. On that basis, a new punching shear reinforcement element with inclined bars was developed. At RWTH Aachen University, 14 punching shear tests on reinforced concrete footings including the new punching shear reinforcement elements were conducted. The test specimens partly failed inside the shear-reinforced zone and at maximum load level. In spite of a reduction of total steel cross sectional area, the test specimens with the new punching shear elements showed a significant increase in punching shear capacity (40-50%) compared to previous test series. The new punching shear reinforcement system allows for a significant reduction of footing's dimensions.