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

Abstract

The influence that the shear lag phenomenon may have on the strength of tubular connections has been addressed in design provisions with variable efficiency factors that affect the tube net area. However, an experimental program carried out on gusset plate connections to the ends of circular hollow section (CHS) members has indicated that these provisions may be overly conservative. As part of the experimental program, a total of eight specimens was tested under quasi-static tension and compression loading considering three connection types frequently used in practice. Moreover, results of a parametric analysis undertaken based on finite element models of these connections (where the responses were verified with the test results) showed considerable differences between the calculated connection strength and the predicted capacity by design provisions. In the finite element analysis, a nonlinear time step analysis was performed considering nonlinear material properties and 8-noded solid elements were used throughout the modeling. The gradual propagation of cracks in the material was emulated by definition of a maximum equivalent strain as the failure criterion with the activation of a “death feature” of the elements. The influence of parameters such as: the weld length ( L w ) , a proposal to use the eccentricity reduced by half the flange-plate thickness ( x ¯ ′ ) and the tube diameter-to-thickness ( D / t ) ratio have been studied. The analysis results have shown that a gradual transition between several failure modes takes place as the weld length increases. Also, the likelihood of developing the full efficiency of the tube net cross-sectional area, if a minimum ratio of L w / w = 1.0 is used, is illustrated.