Behavior and Strength of High-Strength Circular Hollow Section Connections

Abstract

Nowadays circular hollow sections are increasingly used in a wide range of building and offshore structures due to its attractive structural and architectural properties. The use of high-strength steel tubular members can bring about many technological advantages from design to erection. However, most of current design standards including KBC 2009 forbid the use of hollow sections whose yield stress and yield ratio are higher than 360MPa and 0.8, respectively. These limitations appear an unduly conservative technical barrier, and their validity needs to be re-evaluated experimentally and analytically. In this study, a total of 17 full-scale T- and X-Joints of ordinary and high-strength steel circular hollow sections were tested and analyzed to examine the extendability of current design standards. The objective of the present study is not only to extend the understanding to the high-strength steel CHS joints, but also to form the basis of the application of high-strength steel to CHS joints in practice. The key test variables include the strength of steel and geometrical configuration of each joint. The rational to extend the applicability of current design standards was proposed. The CHS joints are investigated numerically using the general purpose finite element (FE) tool ABAQUS, based on the detailed calibration against reported test results. Parametric study is conducted on X- and T-Joints. Combining the results of experimental and numerical parametric study has led to new ultimate strength formulations for X- and T-Joints made of high-strength steel which may serve as a basis for future design recommendations.