大跨度混凝土连续箱梁桥日照温度场试验及仿真分析

为研究大跨连续箱梁桥的日照温度场分布特点与最不利温度梯度模式,以唐山曹妃甸工业区纳潮河2#大桥施工阶段实桥监测为基础,基于太阳物理学、传热学等相关理论,建立箱梁温度场的热边界条件。参考相关文献确定有限元瞬态热分析的环境参数与热工参数,运用ANSYS软件模拟日照下箱梁的瞬态温度场分布并与实测值进行对比分析,采用最小二乘法拟合出箱梁竖向最不利正温度梯度。研究表明:箱梁截面二维温度场近似关于桥轴线对称分布;顶板、底板、东腹板、西腹板内外表面日照最大正温差出现时刻分别为14:00、15:00、11:00、17:00;混凝土导热性能差,内表面峰值温度出现时刻滞后外表面2~3 h;唐山市曹妃甸区箱梁截面的竖向温度梯度为Ty=19.2e-4y;环境与热工参数选取合理,采用有限元软件ANSYS进行数值模拟具有较高精度。

Solar Temperature Field Test and Simulation Analysis of Large Span Concrete Continued Box Girder

To study the solar temperature field and the mode of the most unfavorable temperature gradient of the long span continuous box girder,thermal boundary condition of temperature field for box girder is established based on the theory of solar physics and heat transfer with reference to the monitoring of the construction of Nachao river 2# bridge in Caofeidian industrial district of Tangshan city. Based on relative references,the environmental and thermal parameters of thermal analysis are determined. The transient solar temperature field of box girder is simulated with ANSYS and compared with the measurement,and the most unfavorable vertical temperature gradient curve is fitted by the least square method. The results show that( 1) the distribution of 2-D temperature field of box girder is near symmetrically distributed about the bridge axis;( 2) the maximum temperature differences in roof,floor,east and west web occur at14: 00,15: 00,11: 00 and 17: 00 respectively;( 3) the occurring time of peak temperature in inner surface lags behind by 2 ~ 3 h compared with the outer surfaced due to poor thermal conductivity of concrete;( 4) the vertical temperature gradient of box girder in Caofeidian zone can be obtained by formula Ty= 19. 2e-4y;( 5) based on the reasonable selection of environmental and thermal parameters,simulation of transient temperature field by means of finite element software ANSYS results in higher precision.