复合加固木柱轴压特性试验研究

为了探究内嵌钢筋外包碳纤维(carbon fiber reinforced polymer,CFRP)布复合加固不同截面木柱的加固效果,完成了54根加固木柱的轴心受压试验。考虑内嵌钢筋的数量和CFRP布的布置形式等试验影响因素的变化,分析了不同截面加固木柱的工作性能。试验结果表明:圆形加固木柱与方形加固木柱的破坏过程基本一致,圆形木柱的CFRP布易发生脆性断裂破坏,而由于钢筋的局部外凸作用,方形木柱的CFRP布表现为与木材的剥离破坏;内嵌钢筋可以提高圆形和方形木柱的承载力,CFRP布则能够明显提升圆形木柱的抗压承载力。试件的应力应变曲线分布表明:不同截面木柱的峰值应力和变形能力均随着内嵌钢筋数量以及CFRP布加固量的增加而增加;CFRP布的有效约束作用使其与内嵌钢筋相互促进、协同工作;复合加固方法对圆形木柱的加固效果优于方形木柱。基于试验数据的拟合分析,借鉴纤维复合材料(fiber reinforced polymer,FRP)约束混凝土柱相关理论,建立了复合加固木柱轴心受压承载力计算模型。理论计算与试验结果的对比以及补充试验研究验证了所提出的承载力计算公式的可靠性。

Experimental investigation on axial compression behavior of timber#br#columns strengthened with composite reinforcement method

To investigate reinforcement effectiveness of timber columns strengthened with wrapped CFRP (carbon fiber reinforced polymer) strips and near-surface mounted steel bars, 54 strengthened timber columns with different cross section were tested under axial compression. Working performance of strengthened timber columns with different cross section was analyzed considering the number of mounted steel bars and the arrangement of CFRP strips. Experimental results indicated that the failure process of circular and square columns was almost the same. The CFRP strips of circular timber columns were prone to brittle fracture, while the square timber column showed the debonding failure of CFRP strips caused by local outward bugle of steel bars. Mounted steel bars are able to enhance the bearing capacity of both circular and square timber columns, and CFRP strips can significantly improve the ultimate load of circular timber columns. Stress-strain curves of test specimens show that peak stress and deformation capability of columns with different cross section go up with the increase in the number of mounted steel bars and wrapped CFRP strips. Due to effective confinement, CFRP strips and mounted steel bars can promote mutually and work together. And the effectiveness of composite reinforcement method for circular timber columns is better than that for square timber columns. According to fitting analysis of test data and related theories of concrete columns confined by FRP materials, a calculation model for load-bearing capacity of timber columns with composite reinforcement method was established. The reliability of proposed formula was verified through comparison between theoretical values and test results as well as added experimental research.