复合加固圆形短木柱轴心受压应力-应变关系

STRESS-STRAIN RELATIONSHIP OF SHORT CIRCULAR TIMBER COLUMNS STRENGTHENED BY A COMPOSITE METHOD IN AXIAL COMPRESSION

内嵌钢筋外包CFRP(carbon fiber reinforced polymer)布复合加固方法可以有效提升古建木柱的承压和变形能力,加固效果显著。为了建立复合加固木柱轴心受压应力-应变模型,同时考虑内嵌钢筋数量以及CFRP布加固量等因素的影响,该文完成了42根复合加固木柱的轴心受压试验。试验结果表明:复合加固方法能够提高木柱的受压承载力、改善木柱的延性;由于木材存在有不可避免的初始缺陷,木柱的破坏主要发生于初始缺陷较为集中的区域。相同测点处,木材、CFRP布和钢筋的荷载-应变曲线分布相近,表明木材与CFRP布和钢筋黏结性能良好,三者能够协调变形、共同工作。基于既有的相关研究,通过对试验数据的拟合分析,给出了复合加固木柱轴心受压峰值应力和峰值应变的计算公式,进而提出了三折线型和多项式型复合加固木柱的轴心受压本构模型。考虑到木材材质的离散性,加固木柱的模型计算曲线与试验曲线基本吻合,验证了所得应力-应变模型的可靠性。

The composite reinforcement method with near surface mounted steel bars and wrapped CFRP(carbon fiber reinforced polymer)strips can effectively improve the strength and deformation capacity of historical timber columns.To establish the stress-strain model of strengthened timber columns,42 timber columns strengthened by the composite reinforcement method were tested under axial compression,taking the number of wrapped CFRP strips and near surface mounted steel bars as the experimental factors.The test results indicated that the composite reinforcement method can improve the ductility and compressive strength of the timber columns.Because of the inevitable initial defects of timber,the failure of timber columns mainly occurred in the area where the initial defects concentrated.The load-strain curves of timber,CFRP strips and steel bars were consistent at the same measurement point,which showed that there were good bond properties between the timber and CFRP strips or steel bars,so that they can deform and work together.According to the existing researches,the formulas of peak stress and peak strain of the strengthened timber columns were given by fitting the experimental data.Trilinear and polynomial constitutive models of strengthened timber columns under axial compression were proposed.Considering the discreteness of timber material,the theoretical model curves were consistent with the test curves.It verified the reliability of the obtained stress-strain models.