BFRP布加固圆截面木梁受弯性能试验研究

为研究玄武岩纤维增强复合材料(BFRP)布加固圆截面木梁的受弯性能,对未经加工处理的足尺木梁进行三分点加载试验。试件分为4组总计12根,长度均为3 300 mm。其中1组为未加固试件,另外3组为采用不同方式粘贴BFRP布的加固试件,分别为底部粘贴、底部与侧面环向粘贴、底部与侧面螺旋缠绕粘贴。对各组试件的荷载-跨中位移、荷载-跨中截面应变和跨中截面应变等曲线进行了对比分析。试验结果表明:与未加固试件相比,底部粘贴、底部与侧面环向粘贴、底部与侧面螺旋缠绕粘贴BFRP布的试件极限荷载分别提高了16.30%、24.34%和30.54%。BFRP布加固试件在破坏过程中,木材的塑性变形明显,其抗压强度得到充分发挥,截面应变符合平截面假定。采用ANSYS有限元分析软件模拟得到试件的荷载-位移曲线,与试验结果吻合较好。有限元分析结果表明,试件的受弯承载力随着BFRP布侧面环向粘贴的间距减小而增大。最后,基于BFRP布加固圆截面木梁的三阶段破坏特征,提出其受弯承载力计算公式,计算结果与试验结果的差值小于10%,可为圆截面木梁加固设计提供参考。

Experimental study on flexural behavior of BFRP reinforced circular timber beams

To study the flexural behavior of circular timber beams reinforced by basalt fiber reinforced polymer(BFRP), three-point loading tests are carried out on unprocessed full-scale timber beams. The test specimens are divided into 4 groups with a total of 12 specimens, each with a length of 3300mm. One group includes the unreinforced test specimens, and the other three groups include those with different BFRP cloth reinforcing methods, namely, bottom pasted, bottom and side loop pasted, and bottom and side spiral pasted. The load-displacement curves, the load-strain curves and the strain profiles at mid-span of specimens are compared and analyzed. The experiment results show that the ultimate loads of the three types of reinforced specimens with bottom pasted, bottom and side loop pasted, and bottom and side spiral pasted are increased by 16.30%, 24.34% and 30.54%, compared with the unreinforced group, respectively. During the failure process, the plastic deformation of wood is significant, indicating that the compressive strength is fully utilized. The section strain conform to the plane section assumption. The finite element analysis software ANSYS is used to obtain the load-displacement curves of the specimens. The numerical results are in good agreement with the experimental results.The numerical simulation results show that the flexural capacity of reinforced specimens increases as the distance of the side BFRP cloth is reduced. Finally, based on the observed three-stage failure characteristics, a calculation formula is proposed. The difference between the calculated result and the test result is less than 10%, indicating that the formula is applicable to reinforced circular timber beams.