Interfacial shear behavior of a high-strength pile to sleeve grouted connection

A grouted connection is a type of structural composite connection member produced from two different-sized steel tubes and a grout annulus between them. The grouted connection has been widely used in offshore oil and gas platforms and wind turbine structures by simply grouting between the pile and sleeves. In general, the axial compression strength of the connection is known to be affected by the grout strength, shear-key spacing and radial stiffness parameters of the composite section. In this study, concentric and eccentric loading tests were performed to investigate the interfacial shear behavior of the high-strength grouted connections according to the shear-key spacings. The interface shear behaviors, focusing on the strength, failure mode, and strain of the grout and steel tubes, were evaluated by tests and finite element (FE) analysis. The test results showed that the primary strength of the connection was mainly affected by the grout strength, whereas the ultimate strength was affected by the yield strength of the sleeves and the friction coefficient between the steel tubes and grout. It was also concluded that the test results on the high-strength grouted connections were similar to those of previous studies on normal-strength grouted connections, and the eccentric loading did not reduce the axial capacity of the connection. Although the ultimate failure modes of the connections could not be considered in the current design equations, they may contribute to the safe design of high-strength grouted connections.