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Optimal design solutions of road bridges considering embedded environmental impact and cost

Time: Fri 2022-09-09 13.00

Location: Kollegiesalen; Brinellvägen 8, Campus

Video link:

Language: English

Subject area: Civil and Architectural Engineering, Structural Engineering and Bridges

Doctoral student: Elisa Khouri Chalouhi , Bro- och stålbyggnad

Opponent: Professor Mario Plos, Chalmers

Supervisor: Professor Raid Karoumi, Bro- och stålbyggnad, Järnvägsgruppen, JVG; Adjungerad Professor Costin Pacoste, Bro- och stålbyggnad

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QC 220817


Continuous urbanization and population growth are increasing the demand for transportation infrastructure such as bridges. The construction of these structures represents a significant economic investment for public authorities; moreover, the construction sector accounts for a big portion of CO2 emissions. For countries across the world to deliver on their promises of keeping global warming limited, a change in the design philosophy is needed.

Within the bridge engineering field, a common design approach can be identified as point-based design. While this approach delivers functional solutions, it often results in an expensive and not climate-friendly solution. Design based on structural optimization represents a good alternative as shown by many researchers in the last decades. However, it has not replaced the traditional design procedure yet. Among the reasons, there is the lack in literature of complete design of realistic structures and the complexity of the proposed optimal solutions. Moreover, a collection of recommendations for designers to assist them in the decision-making process is missing as well. 

The aim of this work is to cover the gap between theoretical studies and actual application by proposing optimal design solutions of road bridges that are feasible and simple to build. An automated design and optimization procedure is presented as an alternative to the traditional point-based design with the aim of reducing embedded environmental impact and cost. In the field of road bridges, the procedure is applied to three common structures: reinforced concrete beam bridges, reinforced concrete overhang bridge slabs and decks of composite beam bridges. 

The potential savings obtained by replacing traditional design with the proposed solution are shown through case studies. The use of commercial software commonly employed in design offices and the comparison with existing structures shows the feasibility of the optimal solutions obtained with this approach. Parametric studies are performed to help the potential user make appropriate decisions when performing optimization on these types of structures. As a support in the early design stages instead, recommendations on best solutions are given in the form of graphs and tables. Finally, the relationship between optimal solutions concerning cost and embedded environmental impact is studied for several materials. Material improvements or replacement to further reduce embedded emissions are proposed as well.