Abstract
Abstract The composite floor system, composed of steel deck and concrete slab, generates more efficient and economical structures. On the other hand, the design of this type of structure has a high complexity level due to the consideration of several variables. In this respect, the objective of this paper is to present the formulation of the optimization problem for a composite floor system (steel and concrete) considering such environmental as economic impacts. To formulate the optimization problem, the reduction of environmental impact was adopted as an objective function - assuming the CO2 emission and the finance cost as parameters. The restrictions were taken by the limiting states imposed in standard NBR 8800:2008. The computer program was developed via Matlab R2016a and the optimization process was carried out using the Genetic Algorithm toolbox existing in this platform. Two application examples of the formulation at hand are presented: the first from the literature and the second from an existing building - in both situations the influences of different concrete compressive characteristic strengths were analyzed. The results of the optimization problem show a reduction in geometry and, consequently, in its weight. The solution found by the program reduces by up to 17.70% of CO2 emissions and 17.47% of the finance cost. When was applying different concrete compressive strengths, the optimal solution for environmental impact did not get the lowest cost. In general, the steel deck formwork obtained the highest percentage of environmental impact, while the beams and girders, with the same shape configuration, had the highest finance cost. Therefore, it is shown that the optimal design solution to CO2 emissions is not always the better solution for the finance cost.
Highlights
During the conception of a structural system, several different variables must be considered, to define the most adequate design solution from technical, cost, and environmental perspectives
Two numerical examples are presented to verify the efficiency of the formulation proposed in this paper, one of which extracted from Fakury et al [27] and the other corresponds to an existing structure featuring composite floor systems
The parameter chosen to measure the environmental impact was the CO2 emission resulting from construction processes, considering the total carbon footprint generated from raw material extraction to the final product
Summary
During the conception of a structural system, several different variables must be considered (dimension of structural elements, materials, cost, constructive process, among others), to define the most adequate design solution from technical, cost, and environmental perspectives. Silva and Rodrigues [20] implemented the iterative method of linear sequential programming associated with the Simplex method for the design of steel-concrete composite girders, with the objective of reducing the cost of materials. Despite the large number of studies on the optimization of steel-concrete composite structures available in scientific literature, research presenting both cost and environmental optimizations of systems featuring composite girders and slabs simultaneously are not observed. This paper presents the formulation for optimizing floor systems featuring steel-concrete composite girders and slabs, with the objective of determining the structure with the lowest financial and environmental costs. The formulation proposed here was validated with the example presented by Fakury et al [27] and a composite floor system of an existing structure designed by conventional methods is analyzed
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