THERMAL ACTIONS FOR CONCRETE BRIDGE DESIGN

Thermal effects have been frequently associated with concrete-bridge damage. The nonlinear temperature distributions 'that arise in bridges are not easily estimated and are often considered in a simplified way, which may lead to structural behavior problems. In the present paper, a discussion of current design-code provisions is referred to and an approach studied in Southwest Europe is presented. The estimation of the temperature distributions considers a numerical technique for the resolution of the Fourier heat-transfer equation and its associated boundary conditions. This technique is based on the finite-element method and takes into account the geometry of the bridge cross section, the thermal properties of concrete and asphalt, the location of the bridge, and the climatic conditions. The results of a parametric study developed to evaluate design thermal vertical differences for typical concrete bridge sections are presented. The numerical technique is also applied to the analysis of special cases in which an accurate estimation of thermal effects is necessary.