Breno Dias Breda’s research while affiliated with Universidade Federal do Espírito Santo and other places

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.

Structural optimization is a process that can demands high data processing power depending on the algorithm adopted. In addition, a rigorous geometric nonlinear analysis is performed with iterative numerical algorithms increasing computational efforts. In order to reduce the amount of data to be processed, the Two Cycles Iterative Method (TCIM) is implemented in the Structures3D (S3D), an optimization software under development in Matlab ® using its Genetic Algorithm (GA). The structural analysis, carried out in accordance to Eurocode 3, is also implemented in S3D to improve it as well. The final product is an optimization module that take in account, by approximation, the geometric non-linearity and design by Eurocode 3 of steel structures. An example of application of this module is presented and the result obtained is compared with other author.

The objective of this research is to create a software to optimize choice variables adopted by an engineer in a structural system with steel-concrete composite beams and steel decks, such as: beam shape, composite slab sheeting, number and spacing of beams, slab thickness and interaction ratio between beam and slab. To accomplish this, a program that uses the Genetic Algorithm optimization tool provided by Matlab R2015a was developed. To meet safety requirements, restrictions on the Ultimate Limit State were implemented in the code, following the normative requirements of ABNT NBR 8800: 2008. Case studies of a problem found in the literature and another of a real structure, are presented to serve as references for software evaluation. Results indicate that the use of optimization processes is fundamental to design increasingly cost-effective structures.