Punching Resistance of Flat Slabs with Openings Adjacent to the Columns

The influence of openings in punching shear resistance was investigated, testing eight interior slab-column connections 94.5 in. (2400 mm) square and 5.9 in. (150 mm) thick, with rectangular columns and without shear reinforcement. The openings (one or two) were adjacent to the sides of rectangular supports and had widths equal to 15.7 x 15.7 in. (400 x 400 mm); 7.9 x 7.9 in. (200 x 200 mm); and 7.9 x 11.8 in. (200 x 300 mm). The results of cracking and ultimate loads, vertical displacements, and flexural reinforcement strains were analyzed, and the test results were compared with estimates by ACI 318-19, Eurocode 2 (2014), ABNT NBR 6118:2014, and fib Model Code 2010 (2013). It was shown that the estimates for the slabs with asymmetric large dimension holes improved for all codes considering the eccentricity, as recommended by Joint ACI-ASCE Committee 421.