Practical Tool to Accurately Estimate Tensile Stresses in Concrete Bridge Decks to Control Transverse Cracking

Abstract

This paper describes a simple method to estimate tensile stresses due to early age time dependent loadings in concrete bridge decks with full composite action between the deck and girder. These stresses can cause transverse deck cracking if they exceed the modulus of rupture for concrete, and need to be checked. A system of equations for a pin-roller supported composite girder is developed to estimate the deck stresses due to the volume change in concrete caused by shrinkage and/or other effects. These equations are further extended to consider different boundary conditions. The results of this method agree very well with the results of finite-element analyses. It is proposed that this practical method be used as a tool during bridge design to examine concrete bridge deck stresses against the possibility of transverse cracking. A Microsoft Windows application that is easy to use is developed and presented. Furthermore, an overview of factors causing the volume change in bridge deck concrete and their typical magnitude is presented herein to further simplify the use of this practical method.