木材横纹抗拉力学性能改善方法试验研究

Experimental Study on Improving Tensile Properties of Wood Perpendicular to Grain

木材是成簇纤维构成的材料,在顺纹方向具有较好的拉压性能,但是在横纹方向上由于木纤维间彼此的牵制作用较弱,导致其力学性能远弱于顺纹方向,在工程设计中一般不考虑木材横纹方向的抗拉强度。为研究木材横纹抗拉力学性能的改善方法,本文设计了42个试件进行受拉试验,其中6个为对照组试件,36个为加固组试件,采用了植入自攻螺钉、碳纤维布包裹、植入顺纹木榫、植入单自攻螺钉加FRP布包裹组合方式4种加固方法。通过对试验现象和试验数据的分析,探讨木构件横纹方向加固方法的可行性,对比分析不同方法的效果和差异,研究各组试件在横纹拉力作用下的失效机制、承载力、刚度、延性等力学性能指标。结果表明,加固后的木构件承载力、刚度、延性得到了明显改善,裂缝被有效地抑制,其横纹抗拉性能得到了显著的提高。同时本文结合4种加固方法的特点,提出了可供工程实践参考的建议。

Wood is formed from clusters of fibers,with good strength parallel to the grain.On the other hand,the mechanical properties perpendicular to the grain are weak;tension perpendicular to the grain is generally avoided in engineering practice.In order to study the methods of improving the tensile properties perpendicular to the grain,tensile tests were performed on 42 specimens:6 specimens for a comparison group and 36 specimens for reinforcement groups.Four reinforcement methods are considered,including inserting selftapping screws,wrapping with fiber reinforced polymer(FRP),inserting wooden tenon,and a mixed reinforcement method.Based on the experimental phenomena and test results,feasibilities of the reinforcement methods were discussed;the effects and differences among different methods were evaluated;the failure mechanism,bearing capacity,stiffness and ductility of each group were studied.The results showed that the bearing capacity,stiffness,and ductility of the reinforcement specimens were increased,and the cracks were effectively restrained.Additionally,comparing the four reinforcement methods some suggestions were concluded for engineering practice.