A Study on Temperature Distribution in a Cross Section of Concrete Box Girder Bridge

Abstract

It is known that nonlinear temperature variation over a cross section of long-span continuous box-girder beam bridges or continuous rigid-frame box girder bridges can cause longitudinal stresses and that in some cases such kind of stresses may reaches or even exceeds those induced by the live loads and that temperature cracking may occur in the structure component. However, the mechanism of such phenomenon is not very clear yet. Therefore, to predict the stresses caused by temperature distribution is important for a correct design of the bridge structures. The purpose of the present paper is to present a practical computation method to simulate the temperature distribution over cross sections of a concrete box girder bridge. The relative factors considered include the bridge geometry, the geographical location, the bridge orientation, the material properties and ambient climatic conditions. In this paper heat flow equations over a concrete bridge cross section and heat boundary conditions of outside and in side the box-girder are first derived. And then numerical solution for daily time variation of air temperature is presented. The relationships between inside concrete temperature and ambient climatic conditions that include solar radiation, relative humidity, and wind speed etc. are established. A prediction for variation of concrete temperature is obtained. The results are compared to the observed values measured from The Guangzhou Guanyinsha Bridge that is a single-cell box-girder bridge. Finally, numerical method and computer programming are given to predict the temperature distribute in concrete bridge cross sections. This can be used to generate the thermal loads for finite element analysis.