Grouping and optimization of several slab frame bridges: An analytic and parametric multi-criteria Set-Based Design of several slab frame bridges with a focus on grouping and optimization based on investment cost, environmental impact, and buildability

Abstract

With today’s increasing demand to reduce the carbon footprint of large infrastructure projects, a major focus on material optimization is commonly considered during design. On the other hand, long construction times and delays have created a need to increase productivity without compromising on other important factors such as CO2-emission and investment cost. Previous research has shown that repetition of work steps and standardization of structural components reduces construction time. Using the same structural component for several bridges could be an alternative to reduce construction time. This master’s thesis presents research on grouping and optimization of slab frame bridges using Set-Based Design. Set-Based Design with multi-objective functions was implemented on a Finite Element Method model built in Sofistik, to analyze a large number of bridge alternatives. Different geometric shapes of structural components were combined and evaluated for three different span lengths: 12, 14, and 16 m. The evaluation of bridges was based on the multi-criteria object function Equivalent cost. A resulting library of bridge solutions could thereafter be formed, where it was possible to sort solutions according to object functions and group alternatives by structural components. The result showed that it was possible to optimize a reference bridge and optimization of buildability gave the most noticeable impact on the reference objects. The result also showed that grouping of structural components over multiple spans was possible. A consequence of the grouping was that the bridges that were possible to group, had higher material usage compared to individually optimized bridges. Finally, it was concluded that Set-Based Design with a focus on grouping structural components can be advantageously adopted in future projects to reduce construction time, with the greatest possible impact on large projects.