Investigation on Punching Shear Capacity of Hollow Slab-column Connection

Abstract

To investigate the punching shear capacity of cast-in-situ reinforced concrete hollow slab-column connections under the unbalanced bending moments, a series of specimens were tested and analyzed in this paper. Hollow ratio, direction of moment, tube layout pattern and other factors are considered in the experiment. Performance of the specimens was evaluated in terms of cracking load, ultimate bearing capacity, fracture distribution and load-displacement curve. Moreover, the punching shear capacity formula of the hollow slab-column connections was provided. The experimental results show that the failure patterns of the specimens are punching failure; stiffness improved with the increase of thickness. Under one-direction unbalanced moment, the punching shear capacity decreases with the increase of hollow ratio; Under bi-direction unbalanced bending moment, the punching shear capacity increases with the increase in hollow ratio; the punching shear capacity is higher when bending moment along the tube compared to bending moment cross the tube, but it is not obvious; the specimens under bidirection unbalanced moment have lower punching shear capacity and better deformation ability compared with specimens under one-direction unbalanced moment. Using the proposed punching shear capacity formula, the calculated values are in good agreement with measurements.