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Steel and Composite Structures
  Volume 51, Number 6, June 25 2024 , pages 647-659
DOI: https://doi.org/10.12989/scs.2024.51.6.647
 


Optimal sustainable design of steel-concrete composite footbridges considering different pedestrian comfort levels
Fernando L. Tres Junior, Guilherme F. Medeiros and Moacir Kripka

 
Abstract
    Given the increased interest in enhancing structural sustainability, the current study sought to apply multiobjective optimization to a footbridge with a steel-concrete composite I-girder structure. It was considered as objectives minimizing the cost for building the structure, the environmental impact assessed by CO2 emissions, and the vertical accelerations created by human-induced vibrations, with the goal of ensuring pedestrian comfort. Spans ranging from 15 to 25 meters were investigated. The resistance of the slab's concrete, the thickness of the slab, the dimensions of the welded steel I-profile, and the composite beam interaction degree were all evaluated as design variables. The optimization problem was handled using the Multiobjective Harmony Search (MOHS) metaheuristic algorithm. The optimization results were used to generate a Pareto front for each span, allowing us to assess the correlations between different objectives. By evaluating the values of design variables in relation to different levels of pedestrian comfort, it was identified optimal values that can be employed as a starting point in predimensioning of the type of structure analyzed. Based on the findings analysis, it is possible to highlight the relationship between the structure's cost and CO2 emission objectives, indicating that cost-effective solutions are also environmentally efficient. Pedestrian comfort improvement is especially feasible in smaller spans and from a medium to a maximum level of comfort, but it becomes expensive for larger spans or for increasing comfort from minimum to medium level.
 
Key Words
    footbridge; multi-objective optimization; pedestrian comfort; steel-concrete composite structure; sustainability
 
Address
Fernando L. Tres Junior, Guilherme F. Medeiros and Moacir Kripka:Graduate Program in Civil and Environmental Engineering, University of Passo Fundo, BR 285 Km 292.7, Passo Fundo 99052-900, Brazil
 

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