Parametric Equation for Static Strength of Tubular Circular Hollow Section Joints with Complete Overlap of Braces

Abstract

This paper presents the development of a parametric equation for predicting the ultimate capacity of tubular circular hollow section joint with complete overlap of braces based on the experimental and numerical investigation. In the experiment, a joint specimen with complete overlap of braces is tested to failure under lap brace axial compression for verification of the finite-element (FE) model. The comparison of results showed that the FE model simulates very well the current and the previous test specimens with differences in ultimate capacity and lap brace axial displacement of less than 1.52 and 3.5%, respectively. In the parametric study, the joint ultimate strength is found not significantly affected by the boundary conditions and the chord prestresses. The developed parametric equation based on 3,888 FE models has been verified against the current and the previous test and FE data. A simplified equation in characteristic format for limit state design is also proposed. A comparison with the existing T/Y-joint equations showed that the joint ultimate strength at small gap size is higher. However, the joint ultimate strength decreases with increasing gap size and is found equivalent to that of T/Y-joints at a gap size greater than through brace diameter.