CFRP加固前后桥梁构件超载疲劳试验研究

Overloading simulation fatigue experiment of bridge member with and without CFRP reinforcement

为了精确评估桥梁服役期间超载运营引发的疲劳损伤和失效风险,在对车辆荷载调查的基础上开展了采用碳纤维布(CFRP)加固前后桥梁构件的疲劳试验,分别模拟了一般超载运营、严重超载运营和组合超载运营状态,测试了结构构件超载运营后的承载能力,并对超载运营中的截面应变、裂缝形态、最大裂缝宽度和挠度等参数随超载循环次数的变化规律进行了监测.试验表明:超载运营对桥梁结构的影响主要以疲劳损伤的形式体现,且影响结构的变形能力;单纯衡量结构构件的承载能力不能反映结构的真实服役状态.在模拟超载的低周高应力循环作用下,截面应变随着疲劳次数的增加而持续增长,可近似满足平截面假设.超载运营下桥梁构件的疲劳性能应以钢筋应变和跨中挠度为主要控制指标.

In order to realize accurate evaluation of the fatigue damage and failure risk for existing bridges which suffering vehicle Overloading, fatigue experiments of bridge component with and without carbon fi- ber reinforced plastics （CFRP） reinforcement were carried out based on vehicle load survey. Three over- loading states were simulated, which were general state, serious state and combine state. The capacity af- ter overloading was tested, and the performance parameters, such as section strain, crack pattern, maxi- mum crack width, deflection, were monitored, then the development law of above parameters versus the number of fatigue cycles under overloading were investigated. The experimental results indicate that the capacity cannot be used to refer the service performance of bridge, and a better way to reflect the overloa- ding effect is fatigue damage, which affects the deformation capacity of the bridge structure. The section strain increases with the number of fatigue cycles under low cycle fatigue load. The plane-section assump- tion is still satisfied approximatively till the end of the fatigue cycle. The fatigue performance of bridge component under overloading should be evaluated using steel rebar strain and mid-span deflection as the main control indexes.