Punching shear strength of flat slab strengthened with reinforced concrete column capital under bi-axial loading

Abstract

The punching shear strength of reinforced concrete (RC) flat slab is the main concern in the structural behavior. This study presents a strengthening technique for improving punching shear resistance in RC two-way flat slabs using RC column capital. Two sizes of column capital were used (600 × 600 and 800 × 800 mm), and the influence of column capital on the behaviours of two-way solid slabs under concentric and biaxial loading thus investigated. Six specimens were tested, with two slabs as reference specimens with concentric and biaxial loading, and four slabs with added column capital. The dimensions of the slabs were 1,600 × 1,600 × 100 mm, while the column dimensions were 200 × 200 mm. The eccentricity of the biaxially loaded slab was set to 150 mm in both directions. The results showed a considerable increase in punching shear capacity for flat slabs using column capital; further, as the column capital increased, the punching strength of the slab also increased.