Effect of Chord Load on Ultimate Strength of CHS X-Joints

摘要

Due to inconsistencies between the approaches for circular hollow section (CHS) and rectangular hollow section (RHS) joints, extensive numerical research has been conducted into the chord stress effect of CHS uniplanar K-, T- and X-joints. The objective of these studies is to establish chord stress functions using the maximum chord stress as the major parameter in line with the approach for RHS joints. The current study presents the results of finite element (FE) analyses on CHS uniplanar X-joints under axial brace load with the chord subjected to (ⅰ) axial load, (ⅱ) in-plane bending moment, or (ⅲ) combinations of axial load and in-plane bending moment. The chord stress effect is evaluated for 16 combinations of the geometric parameters β (brace width to chord width ratio) and 2γ (chord width to chord wall thickness ratio). Based on the available FE data, first, a new strength formulation is established for X-joints under axial brace load solely. In addition, a chord stress function is derived, describing the combined effect of axial chord load and in-plane bending chord moment on the ultimate strength of uniplanar X-joints. These formulae will be included in the updated IIW recommendations (2008).