Early Estimations of Dimensions for Prestressed Concrete Bridges: Optimization of cross-section and non-prestressed reinforcement

Abstract

In bridge design, an early estimation of the dimensions and reinforcement content is made to estimate the cost of the bridge. The estimation is generally based upon experience and simplified calculations. From a sustainable as well as economic perspective, it is important to optimize the structures to reduce the environmental impact. This master thesis is a continuation of the work by Aspegren & Möörk (2021) where the prestressed reinforcement was studied. In this master thesis the design will be expanded to also include non-prestressed reinforcement. For optimization, the set-based parametric design method is used in this thesis. It was implemented by further developing a python script by Aspegren & Möörk (2021). In the optimization, the beam height and amount of non-prestressed reinforcement was optimized with the aim to minimize the global warming potential (GWP) and construction cost, respectively, for the superstructure. This work facilitates a more efficient design of continuous prestressed concrete bridges in early stages, that will enhance sustainability and reduce costs instead of designing based on experience and simplified estimations only. The study shows that higher beam heights generally give smaller amount of nonprestressed reinforcement and more optimal solutions with respect to (GWP). However, with the material costs used in the study, the beam height has no significant influence on the investment cost. The potential for more efficient bridge designs were shown in a case study of an existing bridge. The optimization resulted in bridge solutions with approximately 10% reduced cost and 15% reduced GWP.