Strength of slotted tubular tension members

Abstract

An experimental program and associated numerical analysis were undertaken to study the shear-lag effect in round hollow structural section (HSS) tension members that are welded to gusset plates at their ends. The connection is made by slotting the tube longitudinally, inserting the gusset plate, and then placing longitudinal fillet welds at the tube-gusset interface. A total of nine specimens with three different tube sizes (HSS 102 × 6.4, HSS 102 × 4.8, and HSS 219 × 8.0) and various weld lengths were tested in the program. Most of the specimens failed by fracture of the tube somewhere between the two gusset plates, and there was considerable ductility prior to fracture. Most importantly, there was no reduction in the effective net area for the tested specimens, even with a weld length as little as 80% of the distance between the welds. Numerical analyses of the connections were carried out using an elastoplastic model and measured material properties. The studies showed that the restraint provided by the gusset plate at the slotted end effectively increases the load-carrying capacity of the tube as compared with that of the unrestrained portion of the member. In the analysis, fracture is assumed to have occurred when the equivalent plastic strain reaches a critical value. The test results are discussed in light of the requirements in the Canadian standard for design of steel structures.Résumé : Un programme expérimental accompagné d'une analyse numérique a été entrepris pour étudier l'effet du retard de cisaillement dans les membrures de tension de section structurelle creuse ronde (SSC), qui sont soudées à leurs extrémités à des plaques gousset. Pour faire la jonction, le tube est fendu dans la longueur, la plaque de gousset est insérée et des bandes de soudures longitudinales sont placées à l'interface tube-gousset. Un total de neuf spécimens de trois grandeurs de tube différentes (SSC 102 × 6.4, SSC 102 × 4.8 et SSC 219 × 8.0) et de longueurs de soudure diverses, a été examiné dans le programme. La plupart des spécimens se sont rompues par fracture du tube quelquepart entre les deux plaques gousset et il y avait une ductilité considérable avant la fracture. Le plus important, c'est qu'il n'y avait pas de réduction dans la surface nette efficace des spécimens examinés, même avec une longueur de soudure aussi petite que 80% de la distance entre les soudures. Des analyses numériques des jonctions ont été effectuées en utilisant un modèle élasto-plastique et des propriétés de materiau mesurées. Les études ont montré que la contrainte fournie par la plaque gousset au bout de la fente augmente efficacement la capacité de port-charge du tube, comparée à la portion non-restreinte du membre. Dans l'analyse, la fracture est supposée avoir eu lieu lorsque la contrainte plastique atteind une valeur critique. Les résultats des tests sont discutés à la lumière des exigences du standard Canadien de conception de structures en acier.

Parametric finite element study on slotted rectangular and square HSS tension connections

“…Experimental and numerical studies of round slotted HSS connections have also been conducted by Cheng et al [10] and Martinez-Saucedo et al [11]. Finite element analyses from these studies were able to closely predict the load versus deformation curve of the test.…”

“…Finite element analyses from these studies were able to closely predict the load versus deformation curve of the test. Slotted round HSS connections with end welding and a L/w ratio of 1.0 tested by Cheng et al [10] failed at the mid-length of HSS. Other experimental studies on slotted tubular connection include those on very high strength round tubes by Ling et al [12,13], round and elliptical HSS by Willibald et al [14], and round, square and rectangular HSS by British Steel [15].…”

Parametric finite element study of slotted end connections to circular hollow sections

“…In order to consider the material's suppressed necking state that exists in the connections, all the connections were analyzed using several ε e f values and the best correlation between the experimental and FE analysis results for load-strain relationships was found using a ε e f = 0.6. A similar approach (defining a critical strain) has also been used by Cheng et al [7].…”

“…Nine tests on gusset plate connections to CHS tension members were performed and the experimental and numerical investigations showed that considerable stress concentrations occurred at the slot ends. Comparing the results of the study with the then-current Canadian (Cheng et al [7]) as well as American specifications (Cheng and Kulak [8]), it was shown that neither code accurately represented the behaviour of slotted CHS connections. In contrast to the specifications, Cheng and Kulak [8] concluded that the shear lag effect was not critical for CHS if the connection length was longer than 1.3 times the diameter of the CHS; however, all their tests but one were performed with the slot end welded.…”

“…The results of an experimental as well as numerical investigation on shear lag failure for slotted CHS were later given by Cheng et al [6]. Nine tests on gusset plate connections to CHS tension members were performed and the experimental and numerical investigations showed that considerable stress concentrations occurred at the slot ends.…”