冷弯槽钢受弯时长细比限值试验研究

非弹性设计方法与弹性设计方法相比,其截面的允许荷载值较大,这是由于屈服应力沿截面高度进行了重新分布。塑性设计方法使得截面的塑性能力和塑性铰的转动特性得到充分发挥,从而使结构设计更为经济合理。冷弯槽钢在农业和轻工/商业中广泛用于门式刚架结构,塑性设计方法对这类结构非常适用,然而目前仅采用弹性设计方法对其进行设计。为突破设计规范的限制,对冷弯槽钢的非弹性弯曲能力进行了试验研究和数值分析,以建立相应的设计准则。设计准则采用热轧钢分类方法,将截面分为紧凑型、非紧凑型及细长型(根据澳大利亚规范),或1,2,3,4级(根据欧洲规范)。澳大利亚规范所预测的超过弹性极限范围的冷弯槽钢弯曲能力精确可靠。

Slenderness Limits for Cold-Formed Channel Sections in Bending by Experimental Methods

Inelastic design methods allow for larger application of loads on sections than elastic design methods, due to the redistribution of yield stress through the depth of the section. Sections that can reach the full plastic capacity and maintain it for sufficient rotation are considered applicable for plastic mechanism design, resulting in more economical structural solutions. Cold-formed steel channel sections are used extensively in portal frame structures in agricultural and light industrial/commercial applications, structures well suited to plastic design, however may currently only be designed elastically. To address this limitation in design standards, experimental and numerical analyses on the inelastic bending capacity of cold-formed channel sections are performed, and design rules to account for such behaviour are developed. Design rules are prepared using the hot-rolled steel specification methodology of classifying a section as compact, non-compact or slender (according to the Australian Standards) and Classes 1, 2, 3 and 4 (according to the European Standards). Proposals for the Australian standard are shown to provide accurate and reliable capacity predictions for cold-formed steel channel sections whose bending capacity exceeds the elastic limit.