大温差地区未铺装钢箱梁温度梯度预测和温度效应

Temperature Gradient Prediction and Temperature Effect ofUnpaved Steel Box Girders in Large Temperature Difference Area

针对乌鲁木齐地区运营8~10年的钢箱梁桥已经出现裂缝的问题,对作为中国大温差地区的新疆乌鲁木齐地区未铺装钢箱梁桥进行温度监测。基于温度监测数据,用函数拟合的方式描述的钢箱梁太阳辐射下顶底板温差最大时的温度梯度分布模式。选用统计学的方法分析计算100年重现期的钢箱梁日照最不利温差标准值并得到最不利温度梯度模式。基于最不利温度梯度模式,利用Midas Fea NX有限元仿真软件进行最不利温度效应的仿真。研究结果表明:钢箱梁在日照作用下同时存在横向和纵向温度梯度。采用统计分析方法得到100重现期的竖向正温差标准值为29.8℃,高于中国相关现行规范线性插值得到未铺装钢箱梁竖向正温差值26℃。按此温度梯度模式作为温度荷载的有限元结果表明,温度作用下钢箱梁的温度应力达到甚至超过正常设计车辆荷载的应力水平。

In response to the problem that steel box beam bridges that have been in operation for 8 to 10 years in the Urumqi region have developed cracks,temperature monitoring was performed on unpaved steel box beam bridges in the Urumqi region of Xinjiang,which was a region with a large temperature difference in China.On the basis of the temperature monitoring data,the temperature gradient distribution pattern of the steel box beams when the temperature difference between the top and bottom plates under solar radiation maximized was presented by a function fitting method.A statistical method was chosen to analyze and calculate the standard value of the most unfavorable temperature difference of the steel box girder solar radiation for the 100 year return period and to obtain the most unfavorable temperature gradient pattern.Based on the obtained unfavorable temperature gradient pattern,the Midas Fea NX finite element simulation software was used to simulate the unfavorable temperature effect.The results show that both transverse and longitudinal temperature gradients exist in steel box girders under insolation.Using the statistical analysis method,the standard value of vertical positive temperature difference for 100 reproduction periods was obtained as 29.8℃,which is higher than the value of 26℃of vertical positive temperature difference for unpaved steel box girders obtained by linear interpolation in the current specification in China.According to this temperature gradient mode as the finite element results of temperature loading show that the temperature stress of steel box girder under the action of temperature reaches or even exceeds the stress level of normal design vehicle loading.