139 research outputs found
Selection of Production Mix in the Agricultural Machinery Industry considering Sustainability in Decision Making
Get PDF[EN] Competition among companies is growing globally, with the need to increase productivity and efficiency in the product sector. However, there is also a growing concern about global warming and the depletion of natural resources, as well as their effects on human health. In this context, all human activities that involve intense usage of resources must take into account sustainability as one of the decision criteria. This work presents the application of decision-making methods to define the best product mix in the agricultural machinery industry. With this objective, the current schedule of the production line was identified, along with the production flow, by performing an inventory analysis and an environmental impact study (endpoint). A total of seven alternatives for the production mix of grain trailers were defined, considering different materials and production processes. The selection of the best schedule according to the different criteria was performed through the analytic hierarchy process (AHP) and data envelopment analysis (DEA) to evaluate the managerial implications for decision making. The results obtained through AHP identified a single alternative as being the best, which facilitates the decision making. The DEA method identified two alternatives as the most efficient, and in this case the manager can choose between a product mix that generates lesser environmental impact or greater profitability. Although applied to agricultural industry, the presented methodology can be easily adapted to other activities related to the built environment, such as construction industry.The authors acknowledge the financial support the Spanish Ministry of Science and Innovation (Project: PID2020-117056RB-I00), along with FEDER funding to the second author, and the financial support of the Brazilian National Council for Scientific and Technological Development (CNPq) to the last author.Hoose, A.; Yepes, V.; Kripka, M. (2021). Selection of Production Mix in the Agricultural Machinery Industry considering Sustainability in Decision Making. Sustainability. 13(16):1-14. https://doi.org/10.3390/su13169110S114131
Metamodel-assisted design optimization in the field of structural engineering: A literature review
Get PDF[EN] Metamodel-assisted optimization is a valuable alternative to handle structural design optimization procedures, which are usually quite expensive and sometimes even prohibitive. This paper presents an up-to-date literature review on metamodel-assisted structural design optimization (MASDO) in the structural engineering field. The period analyzed is from 2000 to the present, involving 111 publications and 169 case studies. In order to provide practical recommendations on best practices to perform MASDO, eight categorical variables are analyzed, and underlying relationships between them are detected by applying simple and multiple correspondence analysis. Surprisingly, there are fewer published papers on the subject than expected. Most focus on improving or developing metamodeling strategies using simple (benchmark) case studies to validate the proposed methodologies. Consequently, the originality and value of this study lie in the conclusions obtained from the statistical analysis, which serve as a practical guide for incorporating metamodeling strategies in future projects related to structural design optimization.This work was supported by the grant PID2020-117056RB-I00, which was funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe". Grant PRE2021-097197 funded by CIN/AEI/10.13039/501100011033 and by FSE +.Negrín-Díaz, IA.; Kripka, M.; Yepes, V. (2023). Metamodel-assisted design optimization in the field of structural engineering: A literature review. Structures. 52:609-631. https://doi.org/10.1016/j.istruc.2023.04.006S6096315
Otimização multiobjetivo de lajes nervuradas de concreto armado com ênfase na redução de custos e na ampliação da vida útil
Get PDFStructural engineering, one of the major areas of study in civil engineering, is based on the search for optimized solutions that can withstand various actions and ensure the balance of buildings, while also aiming to reduce the consumption of materials and, consequently, costs during the design process. Added to this is the need to design procedures to extend the durability of structures throughout their useful life, since premature deterioration of structural elements, in addition to causing discomfort and generating insecurity for users, is one of the main factors that leads to a considerable amount of the construction industry's resources being spent on repairing and maintaining pre-existing structures. Since minimizing costs and maximizing useful life are conflicting objectives, the applicability of multi-objective optimization concepts and techniques becomes evident. To this end, this study aimed to design reinforced concrete ribbed slab floors – economic alternatives in situations that require large spans – in accordance with the guidelines of ABNT NBR 6118:2014 and respecting the restrictions of the ultimate limit states (resistance) and serviceability (stiffness). The optimization, through the application of the mathematical tool SolveXL® – a Microsoft Excel® add-in that uses genetic algorithms –, aimed to minimize the total cost of concrete, steel and formwork, while simultaneously maximizing the service life. The optimized sections were analyzed in four cases in which the spans varied from 5.0 to 8.0 m, in increments of 1.0 m. For each scenario, the concrete strength classes were sequentially alternated, from C25 to C50. The probabilistic prediction of the service life of the optimized ribbed slabs in this study was made based on the model proposed by the Spanish standard Instrucción de Hormigón Estructural (EHE-08), taking as reference the corrosion process of the reinforcement bars due to carbonation.A engenharia estrutural, uma das grandes áreas de estudo da engenharia civil, tem como alicerce a busca por soluções otimizadas que resistam às diversas ações e garantam o equilíbrio das edificações, ao mesmo tempo em que visam a redução no consumo de materiais e, consequentemente, de custos durante o processo de dimensionamento. Soma-se a isso a necessidade de se conceber, em projeto, procedimentos a fim de estender a durabilidade durante a vida útil das estruturas, uma vez que a deterioração precoce dos elementos estruturais, além de causar desconforto e gerar insegurança aos usuários, é um dos principais fatores para que considerável quantia dos recursos da indústria da construção seja aplicada no reparo e manutenção de estruturas pré-existentes. Sendo a minimização de custos e a maximização da vida útil objetivos conflitantes entre si, evidencia-se a aplicabilidade dos conceitos e técnicas de otimização multiobjetivo. Para este fim, o presente trabalho teve como intento
realizar o dimensionamento de pavimentos de lajes nervuradas de concreto armado – alternativas econômicas em situações que exigem grandes vãos – obedecendo às diretrizes da ABNT NBR 6118:2014 e respeitando as restrições dos estados-limite último (resistência) e de serviço (rigidez). A otimização, mediante a aplicação da ferramenta matemática SolveXL® – um suplemento do programa Microsoft Excel® que faz uso de algoritmos genéticos –, objetivou minimizar o custo total de concreto, aço e fôrmas, em concomitância com a maximização da vida útil. Foram analisadas as seções otimizadas em quatro casos em que os vãos variaram de 5,0 a 8,0 m, em incrementos de 1,0 m.
Para cada cenário, alternou-se de forma sequencial as classes de resistência dos concretos, do C25 até o C50. A previsão probabilística da vida útil das lajes nervuradas otimizadas deste estudo foi feita com base no modelo proposto pela norma espanhola Instrucción de Hormigón Estructural (EHE-08), tendo como referência o processo de corrosão das barras da armadura devido à carbonatação
Study of alternatives for the design of sustainable low-income housing in Brazil
Get PDF[EN] Despite insufficient housing facilities, particularly in developing countries, construction systems are generally selected intuitively or based on conventional solutions sanctioned by practice. The present study aims to evaluate different options for the design of low-income housing in Brazil by integrating the life cycle assessment (LCA) into the decision-making process. To achieve this objective, three single-family projects with different construction systems were selected and analyzed. The most sustainable design was selected through the analytic hierarchy process (AHP). The considered parameters, which were obtained through a survey with professionals and customers, included cost, environmental impact, thermal comfort, construction time, and cultural acceptance. LCA and life cycle cost assessment (LCCA) were performed with the frontier¿s system considering the cradle-to-gate cycle, which included the extraction of raw materials, manufacture of building materials, and housing construction. The projects were modelled using Autodesk Revit software with the Tally application for LCA evaluation. The results indicated that light steel frame houses present a better behavior than other conventional alternatives, and the integration of building information modelling with LCA and LCCA in the design phase can lead to the development of more sustainable houses.The authors acknowledge the financial support of Universidade de Passo Fundo to the first author, the financial support of the Spanish Ministry of Economy and Competitiveness, along with FEDER funding (Project: BIA2017-85098-R) to the second author, and the financial support of the Brazilian National Council for Scientific and Technological Development (CNPq) to the last author.Bianchi, PF.; Yepes, V.; Vitorio, PCJ.; Kripka, M. (2021). Study of alternatives for the design of sustainable low-income housing in Brazil. Sustainability. 13(9):1-15. https://doi.org/10.3390/su13094757S11513
Stochastic Optimization Applied to R-C Building Grillages
No full textThis work presents a formulation developed to minimize the volume of concrete in reinforced concrete building grillages. An association of the displacement method with optimization techniques seeks to obtain the cross-sectional dimensions which lead to the smallest volume of concrete, attending to the ultimate loads (failure) and service loads (deflections). The constraints imposed in the formulation of the problem related to the limitation of the displacements include the effects of instantaneous and long-term deflections, considering an equivalent inertia with the contribution of concrete between cracking (Branson). The determination of the minimum height to each cross-section due to the flexural strength can be performed by fixing neutral axis position or by the maintenance of the section as underreinforced. Due to the relative complexity of the formulation as well as to the existence of local minimas, even for a small number of variables, a stochastic method was chosen, being implemented the Simulated Annealing. In order to verify the efficiency of the proposed procedure, some of the analyzed structures are presented, as well as the results obtained from the implementation of the proposed formulation
Determinação do posicionamento ótimo dos apoios em edificações analisadas pelo modelo de grelha
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No full textO trabalho proposto tem por objetivo a redução e uniformização de esforços em grelhas em função do posicionamento dos apoios, através de técnicas de otimização matemática. Busca-se, pela mudança nas posições inicialmente idealizadas para os apoios, a redistribuição dos esforços em edificações devido à alteração na rigidez relativa dos elementos, de modo a possibilitar maior economia no consumo dos materiais componentes. Objetiva-se ainda, com base na análise de estruturas correntes, verificar a eficiência do procedimento proposto, ainda que consideradas as limitações à livre mudança de posição dos apoios. Com as finalidades descritas, foi desenvolvido um programa de computador que pretende se constituir em uma ferramenta auxiliar ao projetista na fase de concepção da estrutura portante de edifícios. Apesar de direcionada a estruturas de concreto armado, a formulação proposta pode ser adotada para o emprego de outros materiais.The aim of this work is to reduce and to balance the internal forces on grillages based on the support positions, by the application of optimization techniques. By changing the initial position of the supports, a better redistribution of internal forces on the building due to the changes on the relative rigidity of the elements is achieved, consequently reducing the material consumption. Also, the objective is to verify, by means of several examples, the usefulness of the proposed procedure, even considering the limitations to the free displacements of the supports in the plane of the structure. To achieve these objectives, a software was developed, which intends to constitute an auxiliar tool to designers during the process of idealization of the structure. Initially developed to be applied to reinforced concrete structures, the presented formulation can be adopted to the use of other structural materials
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No full textO trabalho proposto tem por objetivo a redução e uniformização de esforços em grelhas em função do posicionamento dos apoios, através de técnicas de otimização matemática. Busca-se, pela mudança nas posições inicialmente idealizadas para os apoios, a redistribuição dos esforços em edificações devido à alteração na rigidez relativa dos elementos, de modo a possibilitar maior economia no consumo dos materiais componentes. Objetiva-se ainda, com base na análise de estruturas correntes, verificar a eficiência do procedimento proposto, ainda que consideradas as limitações à livre mudança de posição dos apoios. Com as finalidades descritas, foi desenvolvido um programa de computador que pretende se constituir em uma ferramenta auxiliar ao projetista na fase de concepção da estrutura portante de edifícios. Apesar de direcionada a estruturas de concreto armado, a formulação proposta pode ser adotada para o emprego de outros materiais.The aim of this work is to reduce and to balance the internal forces on grillages based on the support positions, by the application of optimization techniques. By changing the initial position of the supports, a better redistribution of internal forces on the building due to the changes on the relative rigidity of the elements is achieved, consequently reducing the material consumption. Also, the objective is to verify, by means of several examples, the usefulness of the proposed procedure, even considering the limitations to the free displacements of the supports in the plane of the structure. To achieve these objectives, a software was developed, which intends to constitute an auxiliar tool to designers during the process of idealization of the structure. Initially developed to be applied to reinforced concrete structures, the presented formulation can be adopted to the use of other structural materials
Análise incremental construtiva de edificações
Get PDFThe study of the significance of the consideration of loading and construction sequences in building analysis is the aim of this work. In order to reach this objective a computer program, based on the displacement method, was developed. This program performs the analyses by the conventional procedure and by the incremental constructive procedure. The latter one allows computation of final stresses as well as of the stresses in any construction phase, being possible to model the shoring process, the masonry construction and the research of the maximum and minimum stresses, among other facilities. The presented numerical examples have shown that the conventional procedure does not give good results, being therefore important to use the incremental constructive procedure to obtain a reliable simulation of the real conditions to which structures are submitted.O objetivo do presente trabalho é estudar a importância da consideração da sequência de carregamento e construção, na análise de edifícios, bem como as formas de melhor simular esta sequência. Com esta finalidade foi desenvolvido um programa de computador, baseado no método dos deslocamentos, que efetua a análise tanto pelo procedimento convencional como pelo procedimento incremental construtivo. Este último permite a obtenção não apenas dos esforços finais como também dos desenvolvidos durante uma determinada etapa de construção, podendo-se reproduzir os efeitos do processo de escoramento e da construção das alvenarias ou ainda efetuar a pesquisa dos esforços extremos, entre outras facilidades. Através dos exemplos analisados foi possível comprovar que o procedimento convencional de análise conduz a resultados pouco confiáveis, sendo portanto o procedimento incremental indispensável para que se aproxime às reais condições a que as estruturas são submetidas
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