Ultimate Capacity of Circular Tubular Joints

A total of 137 ultimate strength tests–on simple T, Y, DT, and K tubular joints is used as a basic for development of new ultimate capacity formulas. The data are taken from a variety of sources, and only relatively large geometries are considered. Axial tension, axial compression, in-plane bending, and out-of-plane bending loads are represented. The failure condition is taken as the minimum of either maximum load, first crack load, or load at an excessive deformation limit. Several formulas are recommended to predict the capacity of the different joint and load types. The accuracy of these formulas is then studied in a statistical manner. Predictions of past and present API RP 2A formulas are compared to the same data base. The new relatively simple equations are more consistent in their level of prediction and result in less scatter.