Influence of Steel Plate on Enhancing the Punching Strength of Voided Slabs

Abstract

Punching failure is a possibility for the voided slabs, particularly when they are exposed to unbalanced moments. Thus, the purpose of this investigation is to provide a strengthening method involving the use of steel plates to strengthen the voided slab when it is subjected to an unbalanced moment. The structural performance, especially punching shear of a voided slab reinforced with a steel plate at the interior voided slab-column connections, was examined in this study. Four specimens were constructed using slabs that were 1100 × 1100 × 130 mm and had styropor voids distributed throughout them. A square column that was 250 mm high and with a cross section of 150 × 150 mm was extruded from the upper face of a slab center. An eccentric load was applied via a column stub and an integral beam section, measuring 150 mm by 150 mm, extruded 150 mm from the column face to simulate an unbalanced moment. By inserting two plates in each direction, four steel sheets were implanted into three specimens to reinforce them; the remaining slab was a control without steel plates for strengthening. As well, one slab without voids was created to be a reference of strength degradation due to void insertion. The two other specimens were one voided without steel plates and the other was solid without voids, used as a reference specimen. Near the column stub, these sheets crossed each other orthogonally. Eight square voids, each measuring 250 mm × 250 mm × 70 mm, were present in the voided specimens. They experimented till they failed under an unbalanced moment. Comparing the voided slab with a steel plate to the control slab without strengthening, the test results showed notable improvements in strength, about 8%, ductility to 146%, and toughness, reaching 18%.