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为了探讨碳纤维增强塑料(CFRP)板在沥青摊铺高温环境下加固国外大桥中的疲劳损伤机理及寿命预测,首先介绍Bangabandhu大桥在孟加拉国亚热带湿热环境温度下进行沥青玛蹄脂新桥面铺装的高温加固环境,然后通过钢筋、混凝土和CFRP板应变等参数研究大桥箱梁桥顶板增强梁疲劳裂纹演化、荷载-挠度曲线变化规律及CFRP板应力情况,对梁体抗裂性、刚度和疲劳损伤累积进行分析;最后,根据疲劳裂纹扩展规律和破坏模式,结合试验结果,采用相应的断裂力学分析模型,引入裂纹尖端的应力强度因子计算公式,对试件进行疲劳主裂纹扩展研究。研究结果表明:在沥青摊铺高温作用下,CFRP板仍可以有效抑制混凝土的开裂和裂缝发展,经过CFRP板加固的钢筋混凝土试验梁疲劳寿命有一定提高,经过沥青摊铺高温作用后的CFRP板加固试验梁仍可满足200万次疲劳试验加载。通过da/dN-ΔK曲线和裂纹扩展速率进行疲劳寿命预测发现,该方法计算出的理论疲劳寿命与实际的疲劳寿命基本吻合。
In order to investigate the mechanism of fatigue damage and life expectancy prediction of carbon fiber reinforced plastic (CFRP) slabs strengthened in asphalt pavement under high temperature environment, first of all, introduce the new bridge deck paving of asphalt mastic in Bangabandhu Bridge under the humid and hot environment in Bangladesh subtropical environment Then the fatigue crack evolution, load-deflection curves and CFRP board stress of the reinforced beam of the bridge box girder bridge are studied through parameters such as strain of steel bar, concrete and CFRP board, and the results show that the crack resistance, stiffness and fatigue damage of the girder Finally, according to the rule of fatigue crack growth and failure mode, combined with the test results, the corresponding fracture mechanics analysis model is adopted, the formula of stress intensity factor at the crack tip is introduced, and the fatigue crack propagation is studied. The results show that under the action of asphalt paving, the CFRP board can still effectively suppress the cracking and crack growth of concrete. The fatigue life of the reinforced concrete test beam strengthened by CFRP board has been improved. After being paved with asphalt, the CFRP board Reinforced test beam can still satisfy 2 million times fatigue test load. The fatigue life prediction by da / dN-ΔK curve and crack growth rate shows that the calculated theoretical fatigue life is in good agreement with the actual fatigue life.