开孔冷弯薄壁型钢弯剪构件的屈曲破坏机理及设计方法研究

Functional perforations are usually placed on the webs of cold-formed steel members to facilitate the pipes and electric lines pass through. The existing research on cold-formed steel perforated members were mainly focused on load conditions of compression or bending. However, currently there is no explicit design guideline for the cold-formed thin-walled steel perforated beams subjected to combined bending and shear. Complicated failure modes of the cold-formed thin-walled steel beams may be induced by the web perforations. In this project, the influence of perforations on the failure mechanism of cold-formed steel beams in bending and shear will be studied via theoretical analysis, experimental investigation and numerical simulation. Different buckling mechanism including web shear buckling, flange distortional buckling as well as the interaction of shear and distortional buckling of the perforated beams will be identified. After that, suitable and practical design methods and formulae will be proposed for cold-formed steel perforated members subjected to combined bending and shear with consideration of different buckling modes. The research outcome of this project will provide theoretical and technical support for the design of perforated cold-formed steel members under combined bending and shear in engineering. Moreover, it will encourage more widely application of cold-formed steel in the building structures.

为满足建筑设备管道、线路等通过的需求，工程中通常会在冷弯型钢构件的腹板上设置功能性孔洞。目前针对开孔冷弯型钢构件的研究主要集中在轴压和受弯状态下，而开孔冷弯薄壁型钢弯剪构件的设计与应用尚无明确的规范条文可供参照。因此，本项目将以轻钢结构体系中常见的开孔冷弯薄壁型钢带卷边C形截面弯剪构件作为研究对象，结合理论分析、试验研究与数值模拟，系统地分析开孔对冷弯薄壁型钢弯剪构件屈曲破坏模式和承载力的影响机制；明确开孔构件腹板剪切屈曲、翼缘畸变屈曲、以及剪切屈曲与畸变屈曲耦合作用的失稳破坏机理；提出合理实用的开孔弯剪构件考虑各种屈曲破坏模式的承载力设计方法与计算公式。本项目的研究成果将为开孔冷弯薄壁型钢构件在弯剪共同作用下的设计提供理论支撑，为相关设计规范的制定与补充提供技术支持，从而进一步推广开孔冷弯薄壁型钢构件在工程中的应用。

为同时满足建筑设备管道线路等穿越和节省净空的需求，冷弯薄壁型钢受弯构件的腹板在工程应用中常开设孔洞。当受弯构件所受荷载作用形式不同时，孔洞对构件承载力的影响亦会不同。另一方面，冷弯薄壁型钢梁因板件宽厚比大容易发生板件局部屈曲以及截面畸变屈曲等各种复杂的破坏形式。本项目围绕开孔冷弯薄壁型钢弯剪构件的屈曲破坏机理，通过试验研究、有限元模拟和参数分析，并结合构件上应力分布及发展等理论分析，系统揭示了腹板开孔构件在受剪为主、弯剪共同作用以及受弯为主受力状态下孔洞对构件破坏模式和承载力的影响规律，甑别了其关键影响参数和相应临界值。基于各屈曲模态先拆分后耦合的思路，提出了合理实用的开孔弯剪构件考虑各种屈曲破坏模式相关作用的承载力设计建议。研究成果可为我国《冷弯型钢结构技术标准》的发展提供参考，且为腹板开孔构件在冷弯薄壁型钢结构工程中的应用提供理论参考。