正交异性钢-钢纤维混凝土组合桥面板疲劳极限状态研究

Fatigue Limit State of Orthotropic Steel Plate and Steel Fiber Reinforced Concrete Composite Bridge Deck

为了解正交异性钢-钢纤维混凝土(Steel Fiber Reinforced Concrete,SFRC)组合桥面板的疲劳性能及失效机理,以川南城际铁路临港长江大桥为背景,设计、制作正交异性钢-SFRC组合桥面板足尺模型进行疲劳试验,采用ANSYS软件建立试件有限元模型,研究关键细节的疲劳应力和开裂等情况。基于有限元模型,分析不同设计参数(钢顶板厚度、栓钉布置、SFRC抗拉强度及层厚)下组合桥面板疲劳极限状态的失效模式,并提出了主要控制参数取值建议。结果表明:200万次疲劳加载后足尺模型的实测最大裂缝宽度为0.136 mm,出现在SFRC层上缘,钢结构未开裂,组合桥面板疲劳性能良好;组合桥面板疲劳极限状态主要由SFRC层开裂控制,钢顶板厚度、栓钉布置对组合桥面板疲劳性能的影响较小,SFRC抗拉强度和层厚对组合桥面板疲劳性能影响较大,为主要控制参数;在常规正交异性钢桥面板上铺设薄层(厚度不超过50 mm)SFRC时,SFRC抗拉强度不应小于5 MPa,在常规正交异性钢桥面板上铺设普通SFRC(钢纤维体积含量不高于1%,抗拉强度不高于3 MPa)时,SFRC层厚不宜低于100 mm。

This study investigates the fatigue performance and failure mechanism of the bridge deck composed of orthotropic steel plates acting compositely with the overlaid steel fiber reinforced concrete(SFRC)pavement.The Lingang Changjiang River Bridge of the Intercity Railway of Southern Sichuan is used as a case.A full-scale mockup was prepared for fatigue tests.The fatigue stresses and cracking condition of the critical details of the mockup were simulated in ANSYS,and the failure modes of the bridge deck at fatigue limit state were analyzed considering varying values of design parameters,including the thickness of steel plates,arrangement of studs,and the tensile strength and thickness of SFRC pavement,the values of the primary control parameters were suggested.It is concluded that the measured maximum crack width in the mockup is 0.136 mm after 2 million load cycles,and the cracks are in the upper edge of SFRC pavement,and no cracks are observed in steel components,indicating that the fatigue performance of the composite deck is sound.The fatigue limit state of the composite bridge deck is mainly controlled by the cracking of SFRC pavement,the effects of steel plate thickness and stud layout on the fatigue performance of the composite deck is minor,while the effects of tensile strength and thickness of SFRC pavement are significant,which serve as main control parameters.When placing a thin layer of SFRC(with a thickness less than 50 mm)on the orthotropic steel plates,the tensile strength of SFRC should be no less than 5 MPa.When placing common SFRC(with the steel fiber volume less than 1%and the tensile strength no less than 3 MPa)on the orthotropic steel plates,the thickness of SFRC should be over 100 mm.