We congratulate the authors of the thesis that has won a grant of 50 000 SEK!
An optimization study to reduce embodied carbon using parametric design tools
⇒ Authors: ANNA STIGENBERG, JOHAN LINDQVIST
⇒ Examiner: Associate Professor Ignasi Fernandez, Department of Architecture and Civil Engineering, Chalmers University of Technology
⇒ Department of Architecture and Civil Engineering, CHALMERS UNIVERSITY OF TECHNOLOGY Master’s Thesis ACEX30
Gothenburg, Sweden 2023
Abstract
Today, approximately 11% of the global carbon dioxide emissions are connected to the construction industry, including manufacturing of materials. Due to a continuing global population growth, these values are expected to increase beyond the already high emission levels.
A way to reduce construction emissions is to opt for materials with low embodied carbon to replace conventional materials like steel and concrete. However, for building foundations, material strength and durability are critical factors and the freedom of selecting alternative materials is therefore more restricted. Instead, engineers need to strive to optimize the foundation structure to minimize the carbon emissions. Because of the great portion of material used in foundations, a large decrease of the total carbon emissions for a large variety of structures could be expected by material optimizing the foundation alone.
This thesis investigates on material optimization of piled foundations by utilizing computational tools and optimization algorithms, with the purpose to guide structural engineers to create more CO2-efficient structures. More specifically, it explores how various structural parameters influence the need for material in a piled foundation.
The main results, also summarized in a guideline, includes suggestions on optimal pile center-to-center distances and slab thicknesses for different imposed loads and foundation types. The results also includes comparisons between one-way and two-way foundation slabs, concrete and steel piles, concrete classes as well as a comparison to common practice in the industry.
The thesis concludes that there are possibilities within the design process for engineers to significantly decrease the embodied carbon content of piled foundations. The most important aspects are to reduce the slab thickness, select the pile center-to-center distances to fully utilize the slab, followed by designing the piles accordingly.The carbon optimized design shows potential to save up to 52% of embodied carbon compared to mean values from common practice in the industry.
We congratulate the authors of the thesis that has won a grant of 50 000 SEK!
Development of Guidelines using Genetic Algorithms to Reduce Cost and Environmental Impact
⇒ Master’s Thesis in Master Program Structural Engineering and Building Technology
⇒ Authors: William Mjörnestål, Benjamin Pettersson
⇒ Examiner: Professor/Head of Division Mario Plos, Department of Architecture and Civil Engineering, Concrete Structures
⇒ Department of Architecture and Civil Engineering CHALMERS UNIVERSITY OF TECHNOLOGY Master’s Thesis ACEX30
Gothenburg, Sweden 2022
Abstract
Design of prestressed concrete bridges is a complex and iterative process and have a lot of influencing factors to consider and requirements to fulfil. Even though some attempts at recommendations, engineering practices and software exists, either computation time, efficiency in design or availability may be an issue. As there is a desire in the industry to find more cost-efficient and environmentally sustainable solutions, a need for simple and efficient guidelines in bridge design exists. The aim of this study was to compile general guidelines that can be applied to a varying set of continuous post-tensioned bridges to minimize the cost and environmental impact. The guidelines have been generated from optimization of a bridge beam with varying span length using a genetic algorithm solver. For the structural analyses, a finite element solver was implemented into the optimization script.
When comparing bridges designed with both the proposed guidelines and the conventional solution, load balancing, it was found that significant improvements in cost and notable reductions in global warming potential (GWP) could be achieved with the guidelines. On average, the cost was reduced by almost 7% and the GWP by 5%for the examined cross-section. Other sections were also tested and similar trends could be observed though it was noted that the improvements were considerably smaller for bridges with a slightly wider section. A case study of the road bridge, Halvors länk, showed again that the guidelines were able to reduce the cost by 5%. Due to constraints in cross-section geometry, greater improvements could not be achieved. However, reductions of 11% in prestressing steel amount were obtained for both the original cross-section and the case study, suggesting a more efficient layout.
The study also showed that the use of genetic algorithms can be beneficial in structural design. Implementation of genetic algorithms could, however, increase the computational effort to unreasonable levels depending on the complexity of the problem. Therefore, it could be recommended to compile guidelines from the results of several optimizations utilizing genetic algorithms to be used for more generic problems. With this method, results like that of the genetic algorithm optimization could be achieved but the need for long computations is reduced.
We congratulate the authors of the theses that has won a grant of 50 000 SEK!
Rune Malthe Knudsen & Ann Sofie Hyldtoft Olsen, DTU Lyngby
An experimental study of changes of microstructure of cement based materials with fly ash on chloride ingress
Jørgen Klokkervold & Lauritz Aure, NTNU Trondheim
Integrated structural strength calculations and optimization of CO2 emission for flat slabs with different reinforcement solutions
Nemir Chaudhry & David Bohman, Chalmers Göteborg
Enhanced 3D strut-and-tie method for design of discontinuity regions
