Title: Improved Shear Reinforcement for Footings—Maximum Punching Strength

Author(s): Dominik Kueres, Marcus Ricker, and Josef Hegger

Publication: Structural Journal

Volume: 115

Issue: 5

Appears on pages(s): 1365-1377

Keywords: column perimeter-depth ratio; footings; maximum shear capacity; punching shear; reinforced concrete; reinforcement; shear span-depth ratio

DOI: 10.14359/51702374

Date: 9/1/2018

Abstract:
Besides significantly higher punching strength, footings and ground plates generally exhibit much steeper shear crack inclinations than flat plates. Thus, punching shear reinforcement elements with inclined bars seem to be more efficient than elements with vertical bars. To account for this observation, a punching shear reinforcement element with inclined bars was developed, especially intended for the application in footings and ground plates. In a first test series, seven punching tests on reinforced concrete footings with the newly developed punching shear reinforcement, failing inside the shear-reinforced zone, were performed. Based on the test results, seven further tests were conducted to investigate the maximum punching shear capacity of the new punching shear reinforcement. The test parameters included the shear span-depth ratio av/d, the column perimeter-depth ratio u0/d, the concrete compressive strength fc,cyl, and the layout of punching shear reinforcement. Compared to stirrups and studs, the improved punching shear reinforcement reached significantly larger failure loads. The high efficiency was also confirmed by a comparison of the experimental results with the ACI 318-14 provisions.