Experimental and Numerical Study of Grout Effectiveness and Force-Transfer Mechanism in Socket Connections

Abstract

This study aims to investigate the effectiveness of grout and the mechanism of force transfer in socket connections. In doing so, it proposes a new transfer mode called integral transfer mode (ITM), as opposed to the conventional separate transfer mode (STM). The proposed ITM suggests that, in a reinforced concrete socket connection, if there is a strong bond between the column, grouting material, and receiving member, the socket connection will function as an integral structure, deforming together as a whole rather than as separate components. Consequently, the grouting material does not need to provide a significant lateral bearing force, and the interface shear stresses become the key focus in designing a socket connection. To explore this concept, quasi-static tests and numerical analyses using solid elements were conducted on three half-scale specimens with varying grout strengths. The results demonstrated that the performance of specimens with normal-strength grout was comparable to that of the specimen with high-strength grout. And the proposed ITM was better than STM at predicting failure modes, force–displacement relationships, the stress states of reinforcements, and grout stresses.