摘要
【目标】针对钢筋混凝土梁端部在承受车辆反复作用后易出现疲劳损伤问题,对有初始损伤的梁加固后的疲劳抗剪性能进行试验分析,明晰损伤梁端部抗剪加固后的力学性能,为服役梁受剪区域加固可靠性提供技术支撑。【方法】采用侧面表层内嵌CFRP技术加固钢筋混凝土梁,研究该加固技术下梁的抗剪疲劳力学性能。从试验层面对1榀对比梁和2榀加固梁在疲劳荷载作用下材料应变及加载截面挠度等变化趋势进行分析。考虑到实际服役梁加固时已有初始损伤,为更好模拟实际情况,2榀加固梁(1榀仅在剪跨区域加固,另1榀增加纵向预应力CFRP)均是在承受200万次疲劳载荷后再进行抗剪加固,继而再继续承受50万次疲劳荷载。【结果】2榀加固梁相比未加固梁剩余抗剪承载力分别提升5.6%和9.8%;试验梁的刚度损伤快速下降主要发生在疲劳循环加载的前20万次,之后的刚度损伤速率降低趋于平缓;此外,由于纵向预应力CFRP提高了纵筋的销栓抗剪作用,使得预应力CFRP加固梁的疲劳性能优于普通CFRP加固梁。【结论】侧面内嵌及纵向预应力CFRP复合加固技术有助于提高钢筋混凝土梁的抗剪疲劳性能,可为服役初始损伤梁抗剪疲劳加固提供技术支撑。
[Objective]The end of RC beam is prone to fatigue damage after being subjected to repeated actions of vehicles.It is necessary to study the fatigue shear behavior of beams with initial damage after strengthening,as well as clarify the mechanical behavior of damaged beam end after shear strengthening,thereby providing the technical support for reliable strengthening in the sheared area of beams.[Method]The side near surface mounted(SNSM)CFRP technique was adopted to strengthen RC beams.The shear fatigue mechanical behavior of beams by using this technique were studied.The material strain and the loading cross-section deflection of one comparative beam and two strengthened beams under fatigue loading were analyzed through experiments.Considering the initial damage of actual service beams before strengthening,in order to better simulate the actual situation,two strengthened beams(one strengthened only in the shear span area,and the other strengthened with longitudinal prestressed CFRP)were subjected to 2 million times of fatigue loads before undergoing shear strengthening;and then continued to withstand 500000 times of fatigue loads.[Result]The residual shear bearing capacity of two strengthened beams increase by 5.6%and 9.8%respectively compared with the unstrengthened beams.The rapid decrease of test beam stiffness damage mainly occurs during the first 200000 cycles of fatigue loads.The subsequent decrease of stiffness damage rate tends to be flat.In addition,due to the longitudinal prestressing of CFRP,the shear resistance of longitudinal bars is improved,resulting in better fatigue behavior of prestressed CFRP strengthened beams than ordinary CFRP strengthened beams.[Conclusion]The SNSM and longitudinal prestressed CFRP composite strengthening technique can improve the shear behavior of RC beams,and provide the technical support for shear fatigue reinforcement of beams with initial damage during service.
作者
朱泽文
毛琳
林泽方
欧阳天水
熊山铭
彭培宇
ZHU Zewen;MAO Lin;LIN Zefang;OUYANG Tianshui;XIONG Shanming;PENG Peiyu(Jiangxi Communications Investment Maintenance Technology Group Co.,Ltd.,Nangchang,Jiangxi 330200,China;Jiangxi Jiaoke Transportation Engineering Co.,Ltd.,Nangchang,Jiangxi 330200,China;Road Network Operation Management Company of Jiangxi Communications Investment Group Co.,Ltd.,Nanchang,Jiangxi 330200,China;Ganzhou Traffic Holdings Group Co.,Ltd.,Ganzhou,Jiangxi 341000,China)
出处
《公路交通科技》
北大核心
2025年第8期138-147,共10页
Journal of Highway and Transportation Research and Development
基金
江西省自然科学基金项目(20202BABL214043)
江西省交通运输厅科技项目(2023C0008,2022H0014,2024YB055,2024JT0018)。
关键词
桥梁工程
抗剪性能
疲劳试验
混凝土梁
初始损伤
侧面内嵌技术
CFRP板
bridge engineering
shear behavior
fatigue tests
concrete beams
initial damage
side near surface mounted technique
CFRP strips
