FRP环向加固木柱轴心受压性能试验研究

提供了15根FRP环向加固木柱的轴心抗压性能试验数据,详细探讨了受载后试件的工作机理和破坏模式,试件的设计参数为FRP的层数和FRP的类型,分析了各设计参数对加固木柱承载力和峰值应变的影响。试验结果表明,FRP环向加固木柱可提高木柱的抗压承载力,改善木柱的延性。在极限荷载以前,加固木柱的荷载-应变关系曲线基本保持线性变化,在极限荷载以后曲线为近似理想塑性。加固木柱的承载力和峰值应变随加固层数的增加而增加。3层GFRP可提高木柱承载力和峰值应变分别达21.82%和94.95%。试件的极限荷载和轴向应变随环向FRP的弹性模量的增加而增加,但增幅逐渐变缓。加固木柱达到极限荷载时,环向加固层没有出现拉断现象,其环向应变并未达到环向加固层的极限应变,仅为FRP极限拉应变的10%左右。木柱的破坏始于木纤维的弯曲变形,环向FRP可有效约束这种变形的发展,这是改善木柱轴心受压性能的主要原因。所有试件的破坏模式都表现为木柱产生错动变形,被完全压皱破坏。

EXPERIMENTAL STUDY ON AXIAL COMPRESSIVE BEHAVIOR OF TIMBER COLUMN LATERALLY STRENGTHENED WITH FRP

The results of an experimental investigation concerning the compressive behavior of 15 cylindrical wood columns that are externally wrapped by FRP sheets are presented.The work mechanism and failure modes of the specimens were discussed in details.The parameters of the specimens are number and types of FRP sheets.The effect of design parameters of the specimens on the carrying capacity and peak strain of columns is analyzed.The results show that FRP can effectively improve the compressive bearing capacity and ductility of the wood column by strengthening it laterally.The load-strain curve of reinforced wood column is mainly linear before the ultimate load,and approaching to idealized plasticity post the ultimate load.The carrying capability and peak strain of strengthened timber columns increase along with the FRP sheet number.Capability and peak strain of timber columns wrapped laterally by three sheets of FRP are higher than those of unstrengthened columns by about 21.82%and 94.95% respectively.The ultimate load and axial strain of strengthened timber columns increase along with the elastic modulus of lateral FRP,but the trend becomes weaker.The lateral strengthening sheets are not fractured,and its hoop strain does not reach the ultimate strain,only about 10% of the later.The failure of the wood column begins with bending deformation of wood fiber.The main reason to improve the properties of wood column is that hoop FRP can restrict the deformation efficiently.The failure modes of all the specimens are characterized by alternate deformation and wrinkle.