Abstract
Recent advancements in design guidelines for cold-formed steel members focus on enhancing the prediction of nominal strengths under various loading conditions. This improvement is achieved through precise accounting for local plate buckling behavior. Nevertheless, the Effective-Width Method (EWM), aligned with current design standards, estimates a lower structural capacity for cold-formed steel members. Assuming buckling precedes the yielding of cross-sections and considering no interactive restraint between adjacent elements, conservative predictions of member strengths are derived. To address this issue, this paper introduces a numerical investigation involving several lipped channel cross-sections with varying web height-to-flange width ratios, intending to assess the local plate buckling coefficient (k-value). Initially, validating a shell finite-element model against test results establishes benchmark strengths for the considered cross-sections. Subsequently, analytical solutions for calculating the k-value are presented and compared with those obtained from numerical solutions. Interactions between cross-sectional adjacent elements are examined, leading to a proposed refined EWM compliant with AISI standards. Finally, a reliability analysis is performed to illustrate the accuracy and reliability of the proposed design method. This research highlights the significance of accurately considering the restraining effect between sectional sub-elements and the importance of boundary conditions influencing the plate buckling coefficient.
Publisher
The Hong Kong Institute of Steel Construction