Ultimate Resistance of Unstiffened Tubular Joints

Based on a large number of test results obtained from 747 specimens, an attempt is made to find out simple mathematical expressions that explain the resistances of tube‐to‐tube joints with circular hollow sections under axial brace loading. Multiple regression analysis is performed on a carefully established data base to obtain the best predictive equations. The proposed yield and ultimate strength equations are shown to be in good agreement with the test results, provided that the joints are not controlled by brittle failure. These equations are applicable for wide range of basic variables, which include the geometry and size of the joints, the yield stress and yield ratio of material and the axial stress in the chord. The resistance factors for the design for an ultimate limit state are calculated. It is shown that the standards of tolerance control and material selection and the dimensions of structures must be considered to determine the resistance factor appropriate to the design situations.