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筇竹T型构件力学性能研究
A Study on the Mechanical Properties of T-type node Chimonobambusa tumidissinoda J. R. Xue & T. P. Yi ex Ohrnb
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摘要: 以筇竹T型节点为对象,针对其竹腔狭小、横纹抗拉强度低所导致的连接强度不足问题,采用预埋金属螺母 + α-氰基丙烯酸乙酯胶粘剂固结的增强路径,设计并制作M6 × M10 × L10、M6 × M10 × L15、M6 × M10 × L203种规格的内外牙螺母填充试件。通过抗弯和抗拔试验,测定了各规格螺母对节点极限承载力与变形能力的影响。结果表明:抗弯性能方面,M6 × M10 × L10试件平均最大破坏载荷最高227.63 N,结构刚度和稳定性最优;抗拔性能方面,M6 × M10 × L15试件平均最大破坏载荷最高160.28 N,组内稳定性最佳。破坏模式分析表明,抗弯加载下试件主要发生竹材顺纹劈裂与螺母胶粘剂界面脱粘2种失效形式;抗拔加载下试件主要发生竹材顺纹劈裂与螺母胶粘剂界面脱粘2种失效形式。M6 × M10 × L10推荐用于抗弯主导的节点,M6 × M10 × L15推荐用于抗拔主导且要求高稳定性的节点。Abstract: This study focused on the Chimonobambusa tumidissinoda J. R. Xue & T. P. Yi ex Ohrnb T-type node. To address the issue of insufficient joint strength caused by the narrow bamboo cavity and low tensile strength of the transverse layers, the study employed a reinforcement scheme involving “pre-embedded metal nuts ethyl α-acetylcyanoacrylate adhesive consolidation” to address the issues of narrow bamboo cavities and low tensile strength of the transverse rings, which result in insufficient joint strength. Three specifications of nut-filled test specimens M6 × M10 × L10, M6 × M10 × L15, and M6 × M10 × L20 were designed and fabricated. Through bending and pull-out tests, the effects of each nut specification on the T-type node ultimate load-bearing capacity and deformation capacity were determined. The results show that, in terms of bending performance, the M6 × M10 × L10 specimen achieved the highest average maximum failure load of 227.63 N and exhibited the best structural stiffness and stability; in terms of pull-out performance, the M6 × M10 × L15 specimen achieved the highest average maximum failure load of 160.28 N and demonstrated the best stability within its group. Failure mode analysis showed that under bending loads, the specimens primarily exhibited two failure modes: longitudinal splitting of the bamboo and delamination at the interface between the nut and the adhesive; under pull-out loads, the specimens primarily exhibited the same two failure modes: longitudinal splitting of the bamboo and delamination at the interface between the nut and the adhesive. In summary, it is recommended to use the M6 × M10 × L10 configuration for T-type node dominated by bending and the M6 × M10 × L15 configuration for T-type node dominated by shear that require high stability. This study clarified the influence of nut length on the load-bearing capacity and failure modes of Chimonobambusa tumidissinoda J. R. Xue & T. P. Yi ex Ohrnb T-type node, providing experimental evidence for the reinforcement of furniture T-type node made from this bamboo species, as well as a reference for their standardization, demountability, and large-scale mechanical production.
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