The Punching Shear Strength of Reinforced Concrete Flat Slab under Moments and Shear

Abstract

Eccentric vertical load on a flat slab causes an unbalanced moment called the transferred moment. During the transition, a partial rotation of the slab

occurs around the column, an indirect shear is formed in addition to the direct shear, and the punching shear becomes more dangerous.

An analytical study was carried out to investigate the effect of the transferred moment caused by eccentric vertical loads on the punching shear strength of a flat slab without drop supported on a non-continuous middle column, as well as the presence of different levels of column load and the role of longitudinal reinforcement. The study was carried out with the Abaqus software version 6.14 and a nonlinear static analysis.

The study showed that increasing the percentage of longitudinal reinforcement up to 1% leads to a significant increase in the shear strength of the flat slab, especially when the reinforcement bars are concentrated in the critical shear region around the column. According to this paper, the maximum effective width of the critical shear region was determined by a distance equal to 2d + c + 2d. It was found that the load of the column could reduce the indirect shear in cases of high longitudinal reinforcement ratios (up to 1%) and concentrated bars. The study also showed that replacing the concentrated longitudinal reinforcement bars with a steel section embedded in the slab at the column gives similar results in terms of increasing the shear strength, while the results were better when internal steel sheets were used at the end of the distance 2d+c+2d.