Axial Strength of Grouted Pile‐to‐Sleeve Connections

A new equation for the calculation of axial load transfer in grouted pile‐to‐sleeve connections, either with or without shear keys, is proposed. The general form of the equation was obtained from an ultimate strength formulation for a predicted failure mode of the connection. The ultimate strength equation states that the axial strength of the connection is equal to the sum of two terms: First, the strength of the adhesion and friction between the pile and grout, and, second, the product of the confined strength of the grout and the ratio of the shear key's height to its spacing. The first term was estimated from test results. The second term was estimated from both theoretical considerations and test results, with good agreement between the two approaches. The design equation proposed was obtained by applying separate factors of safety to the two terms. Comparison of the design equation to test data gave a safety index of 3.96 for connections without shear keys, and 4.80 for connections with shear keys. These values imply efficient and reliable design when using this design equation. The design equation has been written into the latest revision to the American Petroleum Institute code of recommended practice.