自攻螺钉在竹木混合正交胶合木中抗拔性能研究

Study on Withdrawal Resistance of Self-Tapping Screws in Cross-Laminated Timber-Bamboo Composites

混合正交胶合木(hybrid cross-laminated timber, HCLT)可以充分发挥不同层板材料特性,改善CLT物理力学性能。研究采用重组竹和速生杉木(Cunninghamia lanceolata),以不同组坯结构制备3类CLT:重组竹CLT、竹木混合CLT和杉木CLT,评价和比较不同直径和钉入深度自攻螺钉(self-tapping screws,STS)在三类CLT中的抗拔性能。结果表明,随着STS钉入深度或直径增加,STS在3类CLT抗拔承载力都增加,且对于重组竹CLT和竹木混合CLT,有利影响程度随着钉入直径或深度增加而增加。STS钉入深度或直径变化对其在3类CLT中抗拔强度影响规律不一致。STS在重组竹CLT和竹木混合CLT的抗拔强度明显大于速生杉木CLT,且对于竹木混合CLT,有利影响程度又随STS钉入深度增加而降低,随STS直径增加而增加。STS在竹木混合CLT中的抗拔性能,受到STS钉入深度、直径和CLT组坯结构等因素多重影响,后续应建立预测模型,量化和优化STS在竹木混合CLT中的抗拔性能。

Hybrid cross-laminated timber(HCLT)fully utilizes the characteristics of different laminae materials to optimize the physical and mechanical properties of CLT.This study applied bamboo scrimber and fast-grown Chinese fir to make bamboo scrimber CLT,cross-laminated timber-bamboo(CLTB),and Chinese fir CLT,respectively.The withdrawal resistances of self-tapping screws(STS)in these three types of CLTs were evaluated.The results showed that as the penetration length or diameter of STS increased,the withdrawal capacity of STS in all three types of CLT increased.The beneficial impact on bamboo scrimber CLT and CLTB also increased.However,the effects of STS penetration length and diameter on its withdrawal strength in the three types of CLT were inconsistent.The withdrawal resistance of STS in bamboo scrimber CLT and CLTB were significantly higher than that in Chinese fir CLT.For CLTB,the degree of beneficial impact decreased with an increase in STS penetration length and increased with an increase in STS diameter.The withdrawal resistance of STS in CLTB is affected by multiple factors,including STS penetration length,diameter,and CLTB layup configuration.Therefore,the next step is to establish a predictive model to quantify and optimize the withdrawal resistance of STS in CLTB.