Otimização multiobjetivo no projeto de lajes mistas de aço e concreto
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Data
2025-08-14
Autores
Silva, Isabela Oliveira Maia da
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Universidade Federal do Espírito Santo
Resumo
The composite steel and concrete slabs have been used as a more economical and sustainable structural alternative since they offer advantages that outweigh other structural systems. Dispensing with formwork and shoring, high construction speed, and reduction in concrete and tensile reinforcement consumption are advantageous features of composite slabs. In this context, the aim of this study is to present the formulation of a multi-objective problem for composite slabs, considering the minimization of CO₂ emissions and final costs, as well as the maximization of load capacity. The design constraints followed the prescriptions of Brazilian standards for both construction and service phases. For the initial phase (before concrete curing), the design consists of verifying the steel formwork supporting the applied loads alone, using the Effective Width Method (EWM) as prescribed by ABNT 14762:2010. For the service phase (after concrete curing), the design was based on ABNT NBR 8800:2024, considering the composite steel system resisting the slab loads. To solve the optimization problem, the MOPSO (Multi-Objective Particle Swarm Optimization) algorithm was used to generate and analyze results through Pareto Fronts. For program validation, a verification of the cataloged slabs was conducted, maintaining their geometric and material properties, and investigating the possibility of loads exceeding those specified in the manufacturer's tables. Solutions were presented that are capable of supporting up to 1.54 times the load indicated by the manufacturer. The formulation was validated using problems from the literature, and an analysis of manufacturer-proposed solutions for different spans was conducted. Additionally, an equation was proposed to relate CO₂ emissions to cost. The results indicate that MOPSO was efficient in finding optimal solutions, yielding results very close to those in the literature using single objective formulations. With the proposed formulation, solutions were achieved with up to 2.4 times the design load proposed in catalogs, and up to 35% lower CO₂ emissions and 30% lower cost due to additional reinforcement. Moreover, solutions were obtained for spans exceeding the maximum limits provided by manufacturers by using concrete with compressive strength greater than 30 MPa. According to the results, the problem constraints are: verification of the steel formwork for bending moments before concrete curing, and verification of the composite section for longitudinal shear after curing
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Otimização multiobjetivo , Lajes mistas de aço e concreto , Formas de aço , Emissão de CO2. , Custo , Capacidade de carga , Composite steel and concrete slabs , Steel forms , Multiobjective optimization , CO2 emissions , Costs , Load capacity