冷弯型钢固废泡沫混凝土异形拼合边柱轴压试验及承载力设计方法

Axial compression test and bearing capacity design method for special-shaped composite edge columns with cold-formed steel and solid waste foam concrete

关键词:  冷弯型钢  异形拼合边柱  固废泡沫混凝土  轴压试验

Key words:  cold-formed steel  special-shaped composite section edge columns  solid waste foamed concrete  axial compression test

摘要:

为提高冷弯型钢拼合柱稳定承载力,进一步拓展冷弯型钢构件应用场景,提出冷弯型钢固废泡沫混凝土异形拼合边柱（CFS-SWFC）。不同于以往焊接钢管混凝土构件,冷弯型钢拼合柱壁厚薄易屈曲且采用自攻螺钉拼接而成,冷弯型钢与核心混凝土的组合效果尚不明确。开展4根异形空腔边柱和6根CFS-SWFC轴压试验,对比分析试件屈曲机制和破坏模式。建立CFS-SWFC数值分析模型,在试验验证基础上开展了多参数拓展分析,研究强度、壁厚和截面尺寸等对试件承载力的影响。基于现行规范GB 50936—2014提出了CFS-SWFC承载力计算方法。结果表明:固废泡沫混凝土提高试件稳定承载力达271%,混凝土强度提高后变形能力最多下降18%,但最终破坏模式未明显改变；FC强度、CFS厚度与截面尺寸对极限承载力影响显著,大截面构件在提升FC强度时极限承载力提升得更高一些；拼合边柱与固废泡沫混凝土存在一定组合效应,现行规范以钢管屈服作为先决条件的计算方法不适用于该类截面,经修正后公式预测效果与试验结果吻合较好,最大误差为13%。

Abstract:

To improve the stability bearing capacity of cold-formed steel composite columns and further expand the application scenarios of cold-formed steel components, an innovative cold-formed steel-solid waste foam concrete (CFS-SWFC) special-shaped composite edge column was proposed. Unlike traditional welded steel tube concrete components, cold-formed steel composite columns are susceptible to buckling due to their varying wall thickness and are assembled using self-tapping screws, making the interaction between the cold-formed steel and the core concrete unclear. Four special-shaped hollow columns and six CFS-SWFC special-shaped composite section columns were tested under axial compression to compare and analyze their buckling mechanisms and failure modes. A numerical analysis model of CFS-SWFC was established. Based on experimental validation, a multi-parameter extended analysis was carried out to study the effects of strength, wall thickness, and cross-sectional dimensions on the bearing capacity of the specimens. A calculation method for the bearing capacity of CFS-SWFC was proposed based on the current code GB 50936—2014. The results indicate that the use of solid waste foam concrete enhances the stability and bearing capacity of the specimens by 271%. Although the increase in concrete strength leads to a maximum decrease in deformation capacity of 18%, the final failure mode remains largely unchanged. The strength of SWFC, the thickness of CFS, and the cross-sectional dimensions have a significant impact on the ultimate bearing capacity. Notably, for larger cross-sectional components, an increase in SWFC strength results in a relatively higher enhancement of the ultimate load-carrying capacity. There is a discernible interaction effect between the composite edge columns and the solid waste foam concrete. The current calculation method, which takes the yield of the steel tube as a prerequisite, is not applicable to this type of cross-section. After modifications, the proposed formula demonstrates a good correlation with the experimental results, with a maximum error of 13%.