Effect of variable-thickness webs on shear buckling performance of welded steel plate girders: numerical analysis and proposed design rules

Abstract

The use of welded steel members with varying thickness webs is becoming more popular and is often used as plate girders to accommodate varying loading distributions. Such variable-thickness steel plates are more susceptible to experiencing out-of-plane shear buckling, particularly in the thinner sections. However, no research work has been described investigating the shear buckling strength of welded steel plate girders with variable-thickness webs. This study presents an extensive numerical analysis to examine the shear buckling strength of such steel members with variable-thickness webs. Finite element (FE) models incorporating the material non-linearity and initial geometric imperfections were developed. To validate the modelling approach employed in this investigation, a total of 41 experimental results reported by the authors and other researchers were used. A detailed parametric study was subsequently undertaken, exploring various variables including local geometrical imperfections, aspect ratio, thickness change ratio, residual stress, and yield strength. To assess the accuracy of the current design regulations, the test and parametric study results were compared against design strengths. Upon comparison, the current design regulations as specified in Chinese Code (GB 50017), American Specification (ANSI/AISC 360-10) and Eurocodes (EN 1993-1-5) are over-conservative when computing the strength of such members with variable-thickness webs. Finally, new design rules covering both cases of variable-thickness and constant-thickness webs are proposed. A reliability analysis was conducted, and the values of β were 2.87, 3.00, and 3.04, respectively, indicating that new design methods developed in this study could closely determine the shear buckling strength of such welded steel plate girders with variable-thickness webs.