无铺装层钢箱梁日照温度场分析

RESEARCH ON TEMPERATURE FIELD OF STEEL BOX GIRDER WITHOUT PAVEMENT CAUSED BY THE SOLAR RADIATIONS

针对我国桥涵设计规范未给出无铺装层钢箱梁日照温度梯度和采用实测方法确定其温度梯度工作量大的不足,根据热传导和有限元基本原理,应用ANSYS建立了江东大桥自锚式悬索桥一段无铺装层钢箱梁三维模型,求解了其温度梯度,并经现场实桥测试,实测值与计算值吻合较好。对钢箱梁日照温度场影响因素进行参数敏感性分析,发现吸收率对温度场计算影响最大,风速次之,辐射率影响最小。以江东大桥钢箱梁日照温度梯度实测数据为基础,采用指数函数加一次函数的形式对钢箱梁日照温度梯度进行了拟合,验证了拟合公式也适用于广州东沙大桥斜拉桥钢箱梁日照温度场的模拟,可推广应用于我国桥梁无铺装层钢箱梁温度梯度的确定。指出在桥梁结构分析时按照英国BS5400规范确定我国桥梁无铺装层钢箱梁温度场可能存在与实际情况较大差别的现象。

In design specifications for highway bridges and culverts of China,no solar thermal gradient is provided for the steel box girder without pavement,as a result,the solar thermal gradient has to be measured on site,which is a heavy work.This paper established a three-dimensional model for a section of the JiangDong Bridge steel box girder without pavement using ANSYS.The temperature field was calculated according to principles of heat conduction.The calculated temperature field at the scene of JiangDong Bridge coincides better with the measured one.Sensitivity analysis was carried out to study the effects of various parameters on the temperature field.The study shows that the absorptivity has the most significant effects on the temperature distribution,the wind speed and the emissivity also have some effects.Based on the measured data of JiangDong Bridge,the formula of exponential function and the linear function are adopted to model the vertical temperature gradient of the steel box girder without pavement.It proves that the fitting formula can also be applied to the solar thermal gradient of DongSha Bridge steel box girder,and can be applied further to the solar thermal gradient field of similar bridges in China.It is finally pointed out British Standard BS5400 may introduce large errors in analyzing the solar thermal gradient field of bridge structures in china.