J.Y.R. Liew

Static strength of thick-walled CHS X-joints—Part I. New approach in strength definition

This paper presents a new approach in the definition of joint strength for thick-walled circular hollow section (CHS) X-joint subjected to brace axial loading. This is based on the plastic load approach for limit analysis of pressure vessel components proposed by Gerdeen. A consistent coefficient λ associated with the plastic load approach has been determined, and the corresponding joint strength for X-joint under brace axial loads is found to correlate closely with the results obtained using Lu’s deformation limit. The strength prediction for thick-walled CHS X-joint using the present approach is found to be in good agreement with design recommendations by ISO and CIDECT for joints with chord radius-to-thickness ratio γ>7. For X-joints with γ<7, significant difference in results is observed especially with the ISO recommendation for joints with brace–chord diameter ratio β≥0.7.

Static strength of thick-walled CHS X-joints—Part II. Effect of chord stresses

Abstract This paper presents results from a parametric study on the effect of chord stresses on the static strength of thick-walled circular hollow section (CHS) X-joint subjected to brace axial loading. The effect of chord stresses in the numerical study is compared to the joint strength equations in ISO and CIDECT. The reference joint strength for thick-walled joint is based on the plastic load approach as reported in the companion paper. For a compression-loaded chord, both design specifications show conservative strength predictions as compared to the present study. For a tension-loaded chord, significant strength reduction is observed in the study which is not considered in the current design specifications. A new chord stress equation is proposed to incorporate the geometric dependency of the chord stress effect as observed in the study. The proposed equation is compared against the numerical results reported by van der Vegte and Makino.

Static strength of plate trunnions subjected to shear loads — part I. Experimental study

Abstract This paper presents the results of an experimental study on the behaviour of plate trunnions subjected to shear loads. The computational study and design considerations for plate trunnions are described in a companion paper. The general test arrangement, structural details and results for nine large-scale specimens are presented. The experimental results show that there is a significant strength contribution from the side braces to the overall plate trunnion strength, which the industry practice ignores. From the tests, two distinct failure modes associated with main-plate dominated, and shear plate or brace dominated responses were observed. The shear yield strengths of the shear plate and side braces are found to provide a consistent lower-bound reference strength for the tested specimens.

Static strength of plate trunnions subjected to shear loads — part II. Computational study and design considerations

Abstract Results from a computational study on the behaviour of plate trunnions subjected to shear loads are presented in this paper. The experimental study on nine large-scale plate trunnion specimens is described in a companion paper. The computational modelling and nonlinear finite element analysis are first presented. The comparison with experimental results shows excellent correlation. The shear yield strengths of the shear plate and side braces are found to provide consistent lower-bound reference strength for plate trunnions. The considerations for design of plate trunnions, including proper evaluation of sling load distribution, dimensioning of trunnion components and fabrication aspects are then presented.