Analyses of Through-Diaphragm Connections to CFT Columns

Available theoretical equations for the shear capacity of composite joints vary in their assumptions for the shear deformation mechanisms and give different equations for calculating its shear strength. This paper discusses previously proposed equations for joint shear capacity, and suggests recommendations for obtaining more accurate predictions. Finite element analyses of through diaphragm connections to CFT columns were carried out in ABAQUS. ABAQUS results and theoretical estimations of the shear capacities were then used to define the properties of a rotational spring in a joint element in OpenSEES representing the shear deformation behavior of the joint. The OpenSEES and ABAQUS results were validated with experimental results from the literature. The results show that: (1) the steel tube flanges and not diaphragms dominate the shear deformation of the joint; and (2) the global behavior of the connection is very sensitive to shear capacity of the joint in joint yielding case.