Experimental Study on Punching Shear Behavior of Pile Caps with Socket Connections

Abstract:

To investigate the influence of socket connections on the punching shear behavior of pile caps. Experimental tests were conducted on 1 cast-in-place （CIP） pile cap and 3 socket connection （SC） pile caps with varying embedment depths and reinforcement configurations. The punching shear performance of SC pile caps was compared with that of the CIP counterpart， and the effects of embedment depth and U-shaped reinforcement on punching shear capacity were examined. Additionally， the existing code formulas for estimating the punching shear capacity of SC pile caps were evaluated and modified based on the test results. The results indicate that SC pile caps exhibit a damage development similar to that of the CIP， albeit with a 6.75% to 7.85% reduction in punching shear capacity. Increasing the embedment depth and incorporating U-shaped reinforcement have minimal impact on vertical load-displacement behavior and punching shear strength of SC pile caps. The study highlights the inadequacy of existing code formulas in capturing the variation of punching shear strength with respect to different embedment depths and reinforcement arrangements. A modified strut-and-tie model is proposed， demonstrating its ability to provide reasonable predictions of the punching shear strength for SC pile caps.