Long term effects & specific problems in concrete & composite bridges

Abstract: Concrete and composite materials are widely used in bridge engineering. Creep and shrinkage long term effects combined with the specific structural behaviour of the bridge make it imperative that more accurate theories and tools are included in the design and analysis of such concrete/composite structures. Some of these problems and their solution in the process of the design and analysis phase of concrete and composite bridges are described in this paper. The basic theory needed for the numerical modelling of long term effects combined with the specific structural behaviour of the bridges are outlined. A consistent solution is made for both linear elastic theory and non-linear theory. The solutions presented have been implemented in a commercially available computer program. The implementation of the solution into the bridge design software is briefly described. The system takes into account all types of loading in the structural calculation including self-weight, pre-stressing, creep and shrinkage etc. The structural engineer has the ability, with such tools, to predict and follow the structural and material behaviour through all the steps of the bridge construction. The modern geometrical pre-processor and the powerful graphical post-processor facilitate the comparison of the behaviour and costs of different variants in a short time. Various bridges have already been designed and analysed using the presented solution and a commercial computer program. The bridges presented in this paper are provided to give insight into some specific problems that were encountered and solved in the design process using the presented solution. Extra focus will be given to comparing specific problems encountered from very long stayed cable bridges such as the Stonecutters bridge in Hong Kong (main span 1018m) with those from medium sized bridges such as Rach-Mieu bridge (main span 270m) in Vietnam.