Resumo As seções mistas de aço e concreto estão cada vez mais sendo utilizadas na construção civil, tanto no cenário mundial quanto no Brasil. O trabalho conjunto do perfil de aço e da laje de concreto aumenta consideravelmente o desempenho do elemento estrutural misto devido ao aproveitamento das vantagens de cada material. Neste trabalho, é utilizado um elemento de barra em conjunto com um elemento de interface para análise não linear de vigas mistas de aço e concreto com interação parcial. O objetivo é montar um algoritmo que utilize essa ferramenta de análise para dimensionar vigas mistas de aço e concreto buscando um projeto otimizado em termos de gastos dos materiais. Definidos os vãos, os apoios, os carregamentos para verificação última e de serviço, um algoritmo de otimização é utilizado para definir as dimensões da seção transversal retangular da laje de concreto, do perfil I de aço e das barras de reforço da laje de concreto, de forma que a quantidade desses materiais seja mínima, garantindo a segurança estrutural, considerando os estados limites último e de serviço. As restrições de projeto são aquelas definidas em normas referentes ao dimensionamento de elementos lineares de concreto, aço ou misto. A função objetivo é definida como sendo o custo por metro linear da viga mista, obtida a partir do custo de cada material, aço, concreto e armadura. No processo de otimização é utilizado o método iterativo de programação linear sequencial, no qual o problema não linear é aproximado por uma sequência de problemas lineares, que tem seu ponto ótimo definido a cada passo usando o método Simplex. Exemplos de vigas mistas para as quais foram definidas suas cargas últimas foram utilizados para validação das implementações. Outros exemplos foram analisados para os quais foram controlados a cada iteração as restrições e função objetivo verificando a funcionalidade do algoritmo.

Abstract The steel-concrete composite sections are often used in civil building in Brazil and around the world. The connection of the steel profile and the concrete slab increases the performance of the composite structural element due to the use of the advantages of each material. In this article, a bar element is used with an interface element for nonlinear analysis of steel-concrete composite beams with partial interaction. The objective is to develop an algorithm that uses this analysis tool to design steel-concrete composite beams looking for project optimized in terms of material costs. Defined spans, supports, ultimate and service load, an optimization algorithm is used to define the dimensions of the rectangular cross section of the concrete slab, I-shaped steel profile, and the reinforcement bars of the concrete slab, so that the quantity of these materials are the minimum to ensure structural safety, considering the ultimate and service limit states. The design constraints are obtained from building code requirements for concrete, steel and composite structures. The objective function is defined as the cost per unit length of the composite beam, obtained from the unit cost of each material, steel, concrete and reinforcement. In the optimization process, the iterative method sequential linear programming is used, in which the nonlinear problem is approximated by a sequence of linear problems, which has its optimum point defined step by step by the Simplex method. Examples of composite beams with ultimate loads defined in the literature were used to validate the implementations. Other examples were analyzed, being evaluated at each iteration the restrictions and objective function to verify the efficiency of the algorithm.

This study aims to assess a new approach for concomitant valorization of two industrial wastes - raw glycerin and spent brewer’s yeast - for the bioproduction of valuable carotenoids. Microbial pigments have numerous applications in the food and cosmetic industries. First, four cultures of yeasts were screened using pure glycerol and either (NH4)2SO4 or urea as carbon and nitrogen sources, respectively. The ability of the best performing culture to accumulate carotenoids was investigated in a medium in which only wastes were supplemented as carbon and nitrogen sources. All the fermentations were carried out in 500 mL-Erlenmeyer flasks containing 150 mL of the medium. Microbial culture was incubated at 30 °C and 150 rpm for 120 h. Particularly, R. marina was the strain with the biggest potential to produce total carotenoids (up to 420 μg g-1). The four major carotenoid pigments identified by LCAPCI-MS were β-carotene, γ-carotene, torulene, and torularhodin. All fermentation assays and all the determinations were performed in triplicate. Results show that the bioprocess proposed in this work is technically and environmentally feasible, and sustainable. The simultaneous use of raw glycerin and spent brewer’s yeast for the production of carotenoids by R. marina is reported for the first time.