Cold-formed steel C- and Z-section beams are widely used in light gauge steel building systems as flexural members. In their applications as flexural members, mono-symmetric C-sections and point-symmetric Z-sections are often subjected to transverse loads eccentric to the shear centre, leading to combined bending and torsion actions. However, research and design methods for cold-formed steel beams subjected to combined bending and torsion are limited. Hence this research has investigated the structural behaviour, strength and design of cold-formed steel C- and Z-section beams under the action of combined bending and torsion. Twenty-four tests were conducted on simply-supported beams subjected to a mid-span eccentric load. Two C-sections and two Z-sections were used in the tests with two different spans, each with three loading-eccentricities. A special test set-up was developed and used to simulate the different loading-eccentricities and to provide accurate boundary conditions. Numerical models of tested beams were then developed using ANSYS and nonlinear finite element analyses including the effects of large deformation and material yielding were performed. The numerical results agreed well with the test results in terms of ultimate strengths, failures modes and load-displacement curves. Finally the results from tests were compared with predictions from the current design equation for bending and torsion. This paper presents this investigation of cold-formed steel beams subjected to combined bending and torsion, and the results.

冷弯型钢的C型截面和Z型截面梁广泛用作轻型钢建筑系统的弯曲构件。在其作为抗弯构件的应用中，单对称C型截面和点对称Z型截面经常承受偏心于剪切中心的横向载荷，从而导致弯曲和扭转作用组合。但是，弯曲弯曲组合的冷弯型钢的研究和设计方法是有限的。因此，本研究研究了在弯曲和扭转共同作用下的冷弯型钢C型和Z型钢梁的结构性能，强度和设计。在承受中跨偏心载荷的简支梁上进行了二十四个试验。在测试中使用了两个C型截面和两个Z型截面，具有两个不同的跨度，每个跨度具有三个加载偏心率。开发了一种特殊的测试装置，用于模拟不同的载荷偏心率并提供准确的边界条件。然后，使用ANSYS开发了测试梁的数值模型，并进行了非线性有限元分析，包括大变形和材料屈服的影响。数值结果在极限强度，破坏模式和载荷-位移曲线方面与试验结果非常吻合。最后，将测试结果与当前设计方程对弯曲和扭转的预测进行比较。本文介绍了冷弯型钢梁在弯曲和扭转作用下的组合研究及其结果。然后，使用ANSYS开发了测试梁的数值模型，并进行了非线性有限元分析，包括大变形和材料屈服的影响。数值结果在极限强度，破坏模式和载荷-位移曲线方面与试验结果非常吻合。最后，将测试结果与当前设计方程对弯曲和扭转的预测进行比较。本文介绍了冷弯型钢梁在弯曲和扭转作用下的组合研究及其结果。然后，使用ANSYS开发了测试梁的数值模型，并进行了非线性有限元分析，包括大变形和材料屈服的影响。数值结果在极限强度，破坏模式和载荷-位移曲线方面与试验结果非常吻合。最后，将测试结果与当前设计方程对弯曲和扭转的预测进行比较。本文介绍了冷弯型钢梁在弯曲和扭转作用下的组合研究及其结果。最后，将测试结果与当前设计方程对弯曲和扭转的预测进行比较。本文介绍了冷弯型钢梁在弯曲和扭转作用下的组合研究及其结果。最后，将测试结果与当前设计方程对弯曲和扭转的预测进行比较。本文介绍了冷弯型钢梁在弯曲和扭转作用下的组合研究及其结果。