Numerical modelling of punching shear behaviour of reinforced concrete flat slab and CFT column connections using steel plates

The shear reinforcement details fabricated for the connections between the Reinforced Concrete (RC) flat slab and interior Concrete-Filled steel Tubular (CFT) column have been developed in many published studies. Of those, the details using steel plates welded directly to steel faces of CFT column have been recently proposed in the literature due to the easiness of fabrication and lower cost. In this study, the 3D nonlinear finite element modelling approach is used to examine the punching shear behaviour of the connections between RC flat slab and interior CFT column using the steel plates as shear reinforcements. The accuracy of the numerical models is verified against the experimental results through comparing the obtained results of formation and propagation of cracks, failure mode of RC slabs, load-displacement relationship, and deformation of shear reinforcement details. Based on the validated numerical models, the parametric studies are conducted to examine the effects of the concrete compressive strength, tensile reinforcement ratio, slab thickness, size of shear reinforcement details, and shape of column cross-section on the punching shear behaviour of the connections. Finally, a new design equation is proposed for predicting the punching shear resistance of the connections between RC flat slab and CFT column.