| An investigation into the thermal response of concrete box girder bridges is presented. It has been documented that structural damage can easily occur due to the effects of temperature. This investigation is concerned with the theoretical prediction of the temperature response in the bridge and comparison with the recorded data. Several cross sections along the bridge were modeled using the computer program FETAB, developed by Elbadry (1982). The input data for FETAB are: environmental data, including the maximum and minimum daily air temperature, diurnal solar radiation, the geometry of the cross section as well as the physical and thermal properties of the materials. FETAB computes the nodal temperatures, the nodal self-equilibrating stresses and the axial strain and curvatures about the two major axis of the cross section. Very good agreement between measured and recorded temperatures, as well as curvatures, was achieved. It was found that one of the most important pieces of data required for accurate temperature predictions was the appropriate value of the convection coefficients, which are dependent on the wind speed. It was determined that the wind speed varied significantly around the girder cross section, thus affecting the convection coefficients around the perimeter of the cross section. The predicted curvatures were compared to those calculated through the use of the recorded temperatures and input into the computer program S-Frame for Windows in order to analyze the longitudinal behaviour of the bridge.; Two cross sections were then analyzed in the transverse direction using the computer program S-Frame for Windows. One cross section near a pier and the other at mid span between piers. The transverse bending moments in the girder walls were found to produce the relatively high stresses. This investigation revealed that the temperature differential through the thickness of the walls and the top and bottom slab of the box section can lead to significant bending moments/stresses when the frame action of the cross section is considered. These stresses, when added to the stresses due to self weight and truck wheel loading, increased the total bending stress by as much as 50% for a 14m deep cross section of the bridge and 24% for the shallower 4.5m cross section of the bridge. (Abstract shortened by UMI.)... |
