Plastic Collapse Analysis of Slender Circular Tubes Subjected to Large Deformation Pure Bending

Abstract

This paper presents a plastic mechanism analysis for thin-walled circular hollow section (CHS) tubes deforming in a multi-lobe or diamond collapse mode under large deformation pure bending. The fold formation process was such that the shell curvature flattened on the compression side transforming into a definite number of flat triangles attached to each other. The collapse proceeded progressively by folding about the base and sides of these triangular planes and over traveling hinge lines. The collapse mechanism was similar to the diamond crush mode. An existing kinematic model for an axially compressed thin-walled circular tube was modified to predict the collapse curve of a thin-walled tube under bending. Inextensional deformation and rigid plastic material behaviour were assumed in the derivation of the deformation energy. Ovalisation was observed during the test and its deformation energy was determined and found significant. An expression for the plastic collapse moment was obtained by equating the total energy absorbed in bending, rolling and ovalisation to the external work carried out during a given cycle of deformation. Comparisons of the predicted post-buckling moments and slopes of the collapse curves with those obtained from experiments carried out by the authors on coldformed circular hollow sections show very good agreement.

Plastic mechanism analysis of steel SHS strengthened with CFRP under large axial deformation

“…3b-6b. In the past, different researchers used different empirical values of the radius of the hinge where r ¼ t s was used in [17] while a larger value of r ¼ 2.5t s was used in [27].…”

“…The effect of CFRP on the collapse of composite circular tubes was studied by Mamalis et al [19,20], Gupta and Abbas [21], Hanefi and Wierzbicki [22] and more recently by Wang and Lu [23]. However, in most of these crush studies, formulations for the mean crush load were derived with little focus on the development of the collapse curves, such as those by Key and Hancock [24], Zhao et al [25] and more recently by Elchalakani et al [26,27] for bending of CHS.…”

Remaining capacity of steel perforated tubular members under compression and bending load scenarios

“…O mecanismo de colapso de tubos com parede fina foi estudado por ELCHALAKANI et al, (2002) (HAN et al, 2006, HILBURGER et al, 2001, JULLIEN & LIMAM, 1998, NISHIMURA et al, 1996, TAFRESHI, 2002, YEH et al, 1999.…”

Plastic mechanism analysis of CHS stub columns strengthened using CFRP

“…The effect of CFRP on the collapse of composite circular tubes was studied by Mamalis et al [10], Song et al [11], Gupta and Abbas [12], Hanefi and Wierzbicki [13] and more recently by Wang and Lu [14]. However, these precious crush studies derive formulations for the mean crush load and little research focused on the development of the collapse curves such as Key and Hancock [15], Zhao et al [16], Grzebieta [17] and more recently Elchalakani et al [18,19] for bending of CHS.…”