钢管混凝土拱肋日照梯度温度效应研究

Sunshine Gradient Temperature Effect of Concrete-Filled SteelTubular Arch Rib

为探究日照辐射作用下钢管混凝土拱肋的梯度温度效应,依托四川省犍为岷江特大桥工程实时采集钢管表面温度,建立了考虑钢管-混凝土界面接触状态的热力耦合模型,进行了钢管混凝土拱肋梯度温度及应力分析,揭示了四川服役的钢管混凝土拱桥在日照影响下其截面梯度温度沿直径D方向的时变规律,及钢管-混凝土界面接触应力在空间方向上的分布模式,并给出了径向梯度温度计算公式以及特征参数取值。研究表明:日照作用下钢管混凝土截面径向温度分布极不均匀,距钢管顶D/8深度范围内温度梯度结果较JTG D60—2015中推荐值高5℃左右,较TB 10092—2017高8℃左右,此外,在D/2处仅为TB 10092—2017推荐值的50%;钢管-混凝土界面应力在1 d内呈现“拉-压”交变现象,在14:00、15:00拉应力峰值高达0.8 MPa,在设计与施工过程中采取适当措施以实现管内混凝土产生超过0.8 MPa的膨胀压应力,避免管内混凝土出现脱空现象。

In order to explore the gradient temperature effect of concrete-filled steel tubular arch rib under sunlight radiation,a thermo-mechanical coupling model considering the interface contact state between steel tube and concrete was established,which was based on the real-time collection of the surface temperature of the steel tube in the Minjiang River Bridge project in Qianwei,Sichuan Province.The gradient temperature and stress analysis of concrete-filled steel tubular arch ribs were carried out and the time-varying laws of the cross-sectional gradient temperature along the diameter D direction and the spatial distribution mode of steel tube-concrete interface contact stress of the concrete-filled steel tubular arch bridge in service in Sichuan under the influence of sunlight were revealed.Moreover,the radial gradient temperature calculation formula and characteristic parameter values were given.The research shows that the radial temperature distribution of CFST section is seriously inhomogeneous under the influence of sunlight.The temperature gradient within the depth range of D/8 from the steel pipe top is about 5℃higher than the recommended value in JTG D60—2015 and about 8℃higher than that in TB 10092—2017.In addition,at D/2,it is only 50%of the recommended value in TB 10092-2017.The interface stress between steel pipe and concrete exhibits an alternating phenomenon of“tension-compression”within one day,with peak tensile stress reaching 0.8 MPa at 14:00 and 15:00.Therefore,the appropriate measures should be taken in the process of design and construction to make an expansion compressive stress of the concrete inside the tube exceed 0.8 MPa,so as to avoid the bond void phenomenon of the concrete inside the tube.