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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。
OBJECTIVE: The stress concentration in the cracked wood column at the compression ends will lead to the development of cracks and the reduction of the co-working performance of timber on both sides, and weaken the compressive bearing capacity of wood columns. With the experimental and numerical simulation, the decreasing rule of the compressive bearing capacity of the longitudinal split wood column under the axial compression and the biasing pressure was discussed. The repair mechanism of the self-tapping screw was analyzed and the critical value and the optimal screw pitch of the longitudinal split column were deduced. Innovative points: 1. To self-tapping screws to achieve longitudinal load-bearing capacity of the compressive strength of wooden columns quickly and effectively and does not affect the appearance of the repair objectives; 2. Experimental and numerical simulation derive the significant decline in the load-bearing capacity of the wooden column to repair the critical value As well as the best value of self-tapping screw spacing. Methods: 1. Studied the effect of longitudinal seam and self-tapping screw on the bearing capacity of wood column through the compression test of the column with longitudinal slits.2. Based on the results of the wood mechanical test of the specimen with fine sample, using the finite element method of numerical simulation, The finite element model with longitudinal seam wood column; 3. The finite element model is used to carry out the parameter analysis, and the influence of the main parameters such as the width of the longitudinal seam and the distance between the self-tapping screws on the repairing effect of the wood column bearing capacity is summarized. The results show that: 1. The decrease of compressive bearing capacity of the longitudinal split wood column is mainly caused by the crack initiation caused by the stress concentration at the joint ends and the decrease of the cooperative work performance of the timber on both sides of the joint; 2. The effective self-tapping screw penetration , So as to delay the development of fractures and restore the synergistic performance of wood; 3. The decrease rate of bearing capacity and self-tapping screw repair rate both increase with the increase of crack width; 4. The crack width in the column of 30 mm in this paper can lead to Wood column load capacity decreased by more than 10%, which can be used as a repair threshold, and 100 mm self-tapping screw spacing can be basically 100% of the bearing capacity repair, which can be used as the optimal screw spacing.