关键词: 桥梁工程, 混凝土箱梁, 有限元模型, 底板温度梯度, 温度效应

Abstract: Temperature effect is an important factor that affects the stress and deformation of concrete box-girder bridges.In order to explore the impact of the bottom plate temperature gradients on the structure，the differences of the bottom plate temperature gradients in vertical temperature gradients of concrete box-girders in both domestic and foreign bridge design codes were contrasted.Based on the measured temperature data of the auxiliary bridge of Sutong Bridge in nearly one year，the measured vertical positive and negative temperature gradients of concrete box-girder were obtained with the least square method.The temperature effect of the measured vertical temperature gradients with and without considering bottom plate temperature gradients was analyzed based on the finite element model of Sutong Bridge.The results show that：without considering bottom plate temperature gradients，vertical positive temperature gradients tend to be safe for the analysis results of temperature stress; but without considering bottom plate temperature gradients，vertical negative temperature gradients tend to be unsafe and the increment of tensile stress can’t be ignored.It is recommended that the distribution modes and characteristic value of vertical positive and negative temperature gradients should be set separately to ensure the reliability of the analysis results.

Key words: bridge engineering, concrete box-girder, finite element model, bottom plate temperature gradient, temperature effect