Abstract This paper presents the details of an experimental and numerical study on the effect of warping on the flexural-torsional buckling (FTB) behaviour of axially loaded cold-formed steel lipped channel members. Eleven controlled experiments on two different lipped channel sections are conducted with simply-supported flexural end conditions. A unique scheme of compression loading is evolved, which allows the ends of the member to warp freely. Experimental investigations reveal that warping end conditions play a significant role in the compressive strength and failure modes. The results from the experiments are used to calibrate the numerical model developed using ABAQUS. Parametric studies are conducted on different cross-section sizes of the members to quantify the effect of warping restraint on the FTB strength under compression. Results are compared with the current AISI S100–16 specification using both the effective width method (EWM) and the direct strength method (DSM). The comparison of results reveals that for warping restrained condition, the present DSM framework based on the finite strip method (FSM) predicts FTB strength conservatively. A possible correction factors are identified for members with warping restrained ends, which can be applied over the traditional strength curve in DSM. A reliability study is also carried out on the modified design procedure for the FTB strength of CFS members.

中文翻译：

---

具有翘曲约束的薄壁通道截面的弯扭屈曲强度

摘要 本文详细介绍了翘曲对轴向加载的冷弯型钢唇形槽钢构件的弯扭屈曲 (FTB) 行为影响的实验和数值研究的详细信息。在两个不同的唇形通道截面上进行了 11 个受控实验，使用简单支撑的弯曲端部条件。一种独特的压缩加载方案得到了发展，它允许构件的端部自由翘曲。实验研究表明，翘曲末端条件在抗压强度和破坏模式中起着重要作用。实验结果用于校准使用 ABAQUS 开发的数值模型。对构件的不同横截面尺寸进行参数研究，以量化翘曲约束对压缩下 FTB 强度的影响。使用有效宽度法 (EWM) 和直接强度法 (DSM) 将结果与当前的 AISI S100-16 规范进行比较。结果的比较表明，对于翘曲约束条件，目前基于有限条法（FSM）的 DSM 框架保守地预测 FTB 强度。为具有翘曲约束端部的构件确定了可能的修正系数，可应用于 DSM 中的传统强度曲线。还对 CFS 成员 FTB 强度的修改设计程序进行了可靠性研究。目前基于有限条法 (FSM) 的 DSM 框架保守地预测 FTB 强度。为具有翘曲约束端部的构件确定了一个可能的修正系数，可应用于 DSM 中的传统强度曲线。还对 CFS 成员 FTB 强度的修改设计程序进行了可靠性研究。目前基于有限条法 (FSM) 的 DSM 框架保守地预测 FTB 强度。为具有翘曲约束端部的构件确定了可能的修正系数，可应用于 DSM 中的传统强度曲线。还对 CFS 成员 FTB 强度的修改设计程序进行了可靠性研究。