钢箱-混凝土组合桥梁防腐涂层的疲劳应力分析

Fatigue Stress Analysis of Anti-Corrosion Coatings on Steel Box-Concrete Composite Beam Bridge

为分析钢箱-混凝土组合桥梁防腐涂层在疲劳应力下的破损机理,基于应力等效原则,采用ANSYS软件建立了钢箱-混凝土组合桥应力最大部位的局部非线性分析模型,分析了涂装及钢结构基材在车辆疲劳荷载下的疲劳应力及涂层的裂缝发展模式。结果表明:涂层在未达到其极限强度以前,随疲劳循环次数的不断增大,涂层在一定范围内越厚,界面拉应力越小,界面剪应力越大,界面融合性越好,抗疲劳性越强。跨中最大应力部位的涂层因界面拉应力过大将出现拉裂破坏。对于本工程涂层,考虑钢结构最大应力部位的疲劳作用,150 pm涂层面漆层的疲劳寿命约为17.8 a、300 pm涂层面漆层寿命可达22.8 a,因此在设计时应该充分考虑疲劳应力对涂层破损失效的影响。

In order to analyze the failure mechanism of the anti-corrosion coatings on the steel box-concrete composite bridge under fatigue stress,a local nonlinear analysis model of the maximum stress portion in the steel box-concrete composite bridge was established based on the principle of stress equivalence,by means of ANSYS software.It analyzed the fatigue stress of the steel structure substrate under the fatigue load of the vehicle and the crack propagation mode of the coatings.The results showed that as the number of fatigue cycles continued to increase,the thicker the coatings in a certain range,the smaller the interface tensile stress,the larger the interface shear stress,the better the interface fusion,and the stronger the fatigue resistance before the coatings reached its ultimate strength.The coatings in the areas with the largest stress in the middle of the span would be damaged due to excessive tensile stress at the interface.Considering the fatigue effect of the maximum stress part of the steel structure on the coatings in this project,,the fatigue life of the 150μm thickness topcoat layer was about 17.8 years,and the life of the 300μm thickness topcoat layer could reach 22.8 years,therefore,the effect of fatigue stress on the failure of coatings should be fully concerned in the design of the project.