CFRP增强胶合木梁刚度退化试验研究  

Experimental study on stiffness degradation of CFRP reinforced glulam beams

作　　者：易锦[1,2] 祝彬 贺国京[1,2] 周煜 YI Jin;ZHU Bin;HE Guojing;ZHOU Yu(School of Civil Engineering,Central South University of Forestry&Technology,Changsha 410004,Hunan,China;Manufacture and Application of Modern Wood Structure Engineering Materials Hunan Engineering Laboratory,Central South University of Forestry&Technology,Changsha 410004,Hunan,China)

机构地区：[1]中南林业科技大学土木工程学院,湖南长沙410004 [2]中南林业科技大学现代木结构工程材制造及应用湖南省工程实验室,湖南长沙410004

出　　处：《中南林业科技大学学报》2021年第4期165-172,共8页Journal of Central South University of Forestry & Technology

基　　金：国家自然科学基金项目(51578554);国家林业公益性行业科研专项(201304504);湖南省教育厅项目(17C1654)。

摘　　要：【目的】大多数工程构件失效是由于一系列的循环载荷所产生的疲劳损伤累积而造成。在循环反复的荷载作用下,当保持相同的峰值荷载时,峰值点位移随循环次数的增加而增大,这种现象称为刚度退化。本研究旨在研究CFRP增强胶合木梁的刚度退化,为CFRP增强木结构的工程应用提供理论参考。【方法】基于前人对于胶合木梁疲劳性能的研究结果,开展了CFRP增强胶合木梁疲劳试验。通过3根试验梁在不同荷载上限作用下的等幅疲劳试验,研究胶合木梁在CFRP增强下的疲劳特性、破坏机理以及刚度退化情况。【结果】根据CFRP增强胶合木梁疲劳试验结果,由于承载力的下降,3根试验梁均发生了疲劳破坏,其疲劳寿命分别为1120985、617313、286486次。通过对各试验梁的刚度退化曲线进行分析拟合,可以得出CFRP增强胶合木梁的破坏刚度比平均值为0.8529,方差为0.0435。【结论】试验证明在裂纹形成后CFRP延缓了裂纹扩展速度,降低了试验梁刚度退化的速率,从而提高了胶合木梁的疲劳寿命。分析拟合刚度退化曲线,可以看出随着疲劳循环荷载次数增加,试验梁的抗弯刚度均呈下降趋势。疲劳荷载等级越高,刚度退化越快,且基本呈线性变化。通过对比,CFRP增强胶合木梁的平均破坏刚度比未增强胶合木梁低了2.59%。这表明CFRP对胶合木梁有一定的增强作用,并且可以延缓试验梁因刚度退化而引起的疲劳破坏。【Objective】Most engineering component failures are caused by the accumulation of fatigue damage caused by a series of cyclic loads.Under the load of repeated cycles,when the same peak load is maintained,the displacement of the peak point increases with the increase of the number of cycles.This phenomenon is called stiffness degradation.This article aims to study the stiffness degradation of CFRP-reinforced glulam beams and provide a theoretical reference for the engineering application of CFRP-reinforced wood structures.【Method】Based on the previous research results on the fatigue properties of glulam beams,the fatigue test of CFRP reinforced glulam beams was carried out.Through the fatigue test of three test beams under different load upper limit,the fatigue characteristics,failure mechanism and stiffness degradation of glulam beam under CFRP reinforcement were studied.【Result】According to the fatigue test results of CFRP reinforced glulam beams,three test beams all suffered fatigue failure due to the decrease in bearing capacity,and their fatigue life is 1120985 times,617313 times and 286486 times respectively.By analyzing and fitting the stiffness degradation curves of each test beam,the average failure stiffness ratio of CFRP reinforced glulam beam is 0.8529 and the variance is 0.0435.【Conclusion】The test shows that CFRP delays the crack growth rate after the crack is formed,reduces the rate of stiffness degradation of the test beams,and thus increases the fatigue life of the glulam beams.By analyzing stiffness degradation curve,therefore we can conclude that as the number of fatigue cycle loads increases,the flexural rigidity of the test beams shows a downward trend.The higher the fatigue load level,the faster the stiffness degenerates,and it basically changes linearly.By comparison,the average failure stiffness of CFRP-reinforced glulam beams is 2.59%lower than the unreinforced glulam beams.This indicates that CFRP has a certain strengthening effect on the glulam beams,and can also delay the

关 键 词：胶合木梁 等幅疲劳 CFRP 刚度退化 

分 类 号：S781.29[农业科学—木材科学与技术]