FRP加固木梁受弯承载力与挠度研究

Analysis on flexural capacity and deflection of wood beams strengthened with FRP

基于木梁受弯时典型的M-δ曲线,对FRP加固木梁常见的两种受弯破坏模式(拉区木纤维拉断和压区木纤维压皱)的弹性阶段和弹塑性阶段进行了全过程应力应变分析,并基于木材等效最大压应力Chen本构模型,建立了FRP加固木梁在弹性极限和弹塑性破坏时的受弯承载力和挠度公式,采用线性插值的方法得到FRP加固木梁的全过程挠度.同时,通过对三根木梁进行四点弯曲试验,研究FRP加固木梁受弯后的破坏模式、极限承载力和挠度等抗弯性能.试验结果表明:受拉面粘贴FRP布可有效提高木梁的极限承载力,相比对木梁承载力的影响,配FRP布率对木梁截面刚度提高不够显著,试验结果与笔者所建立的理论公式计算值吻合较好,为今后FRP布加固木梁的计算提供理论依据.

According to the typical M-δ curve of wood beams,an entire process stress-strain analysis was made to the strengthened wood beams under elastic stage and elastic-plastic stage when the two common flexural failure modes,tensile wood fiber rupture and compressive wood fiber crushing,were happened.Based on the equivalent maximum compressive stress model of Chen,deriving the formulas of flexural capacity and deflection of strengthened wood beams at elastic limit and elastic-plastic failure respectively,then,a linear interpolation method was used to get the entire process deflections.Meanwhile,three wood beams were conducted with four points bending test to investigate the failure mode,ultimate flexural capacity and deflection.The experimental results showed that,it could increase the ultimate bearing capacity effectively by pasting FRP on the tension surface,the strengthening ratio has poor sensitivity to the stiffness compare with the influence of bearing capacity.The flexural capacity and deflection results from these theoretical formulas agree well with the experimental results,it provides a theoretical basis for FRP strengthening wood structures in the future.