PREDICTION OF TEMPERATURE AND STRESSES IN HIGHWAY BRIDGES BY A NUMERICAL PROCEDURE USING DAILY WEATHER REPORTS

Abstract

This research focused on the development of computational procedures for the prediction of the transient bridge temperature distribution due to daily variations of the environment such as solar radiation, ambient air temperature, and wind speed. The temperature distribution is assumed to be constant along the centerlines of the bridge but can vary arbitrarily over its cross section. The finite element method was used for the two-dimensional heat flow analysis. Temperature stresses, however, are computed from elastic beam theory. In this work a computer program, TSAP, which included the heat flow and thermal stress analysis in a complete system was developed. The environmental data required for inout are the solar radiation intensity, ambient air temperature and wind speed. Daily solar radiation intensity is available through the U.S. Weather Bureau at selected locations while air temperature and wind speed can be obtained from local newspapers. This program provides a versatile and economical method for predicting bridge temperature distributions and the ensuing thermal stresses caused by daily environmental changes. Various types of highway bridge cross-sections can be considered. In this work, three bridge types are considered: (1) a post-tensioned concrete slab bridge, (2) a composite precast pretensioned bridge, and (3) a composite steel bridge. Specific attention was given to the extreme summer and winter climatic conditions representative of the city of Austin, Texas. /Author/