新型自攻螺丝修复纵裂木柱抗压性能（英文）

Compressive capacity of longitudinally cracked wood columns retrofitted by self-tapping screws

目的:受压纵裂木柱缝端应力集中会引起裂缝发展和两侧木材协同工作性能下降,并削弱木柱抗压承载力。以试验和数值模拟探讨轴压和偏压作用下纵裂木柱抗压承载力的下降规律,分析自攻螺丝的修复机理,推导纵裂木柱修复临界值和最优螺丝间距。创新点:1.以自攻螺丝实现纵裂木柱抗压承载力快速有效和不影响外观的修复目标;2.以试验和数值模拟推导纵裂木柱承载力显著下降而需修复的临界值以及自攻螺丝间距的最优取值。方法:1.通过带纵缝木柱抗压试验研究纵缝及自攻螺丝对木柱承载力的影响;2.运用精细化有限元数值模拟方法,基于清样小试件木材力学测试结果,建立带纵缝木柱有限元模型;3.运用有限元模型开展参数分析,归纳整理纵缝宽度及自攻螺丝间距等主要参数对木柱承载力修复效果的影响。结论:1.纵裂木柱抗压承载力下降主要由缝端应力集中引起的裂缝开展和缝两侧木材协同工作性能下降引起;2.新型自攻螺丝垂直裂缝方向贯入可实现有效拉结,从而延缓裂缝开展和恢复木材协同工作性能;3.纵裂木柱承载力下降比率和自攻螺丝修复率均随裂缝宽度的增加而增加;4.本文中30 mm的柱中裂缝宽度可导致木柱承载力下降超过10%,因而可作为修复的临界值,而100 mm的自攻螺丝间距可基本实现100%的承载力修复,因而可作为最优螺丝间距。

This paper presents the results of an experimental and numerical study of the compressive capacity of longitudinally cracked wooden columns retrofitted using self-tapping screws. The screws were driven into the wood perpendicular to the wood grain to alleviate the propagation of existing cracks and to improve the structural integrity of the cracked columns. Full-scale concentric and eccentric compression tests were conducted to investigate the failure modes and maximum load carrying capacity of such columns. A 3D finite element model was developed, verified, and then used for a parametric study. The test results indi- cated that the cracks （of 6 mm wide） caused a resistance loss of up to 19% compared with an intact column, but most of this resistance loss can be remedied by using self-tapping screws. It was also found that such resistance loss and recovery are de- pendent on the seriousness of the cracking, and generally increase with the increased initial mid-height deflection and decreased screw spacing, whereas a screw spacing of 100 mm would be sufficient for most cases considered in this study.