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In the last decades, the modernization in structural engineering has increased the use of steel-concrete composite and hybrid systems for slabs, when the adherence in the interface of the materials is present or not, respectively. In addition to the traditional steel deck, a similar solution for precast trussed slabs has been used for small constructions, in which a cold formed U profile acts as steel formwork before the concrete curing, resisting to self-weight of the concrete and to the construction overload. After this period, the steel profile gets incorporated to the concrete element, allowing the composite behavior of the structure, system that usually goes without additional reinforcements. This slab includes, besides concrete, a light filling material between ribs, cold formed profiles and the trussed reinforcement. Once this technology has just arrived to the construction market, there is a gap of knowledge related to its design procedure. In this context, this study aims to present a methodology to analyze the limit-states that govern the design of these slabs. A computational tool was developed to evaluate the resistance through data entry related to geometry, service loads and materials, which grants to conduct a parametric study with pre-defined geometries to obtain, as result, spans and loads. Conclusions about the maximum span without shoring and general data are also discussed. Keywords Steel-concrete composite slabs, trussed slabs, cold formed U profile, design procedure. Evaluation of the resistance of trussed slabs with steel formwork in cold formed U profile Lucas Fadini Favarato et al. Latin American Journal of Solids and Structures, 2019, 16(7 Thematic Section), e178 2/18 (2015) also states that the major advantage in the use of this structural technology is related to the fabrication process: thin plates, with small resistance in its original shape, are stiffened where buckling can occur. Hence, the folding procedure changes steel original mechanical properties, leading to highest yield and ultimate strengths. Otherwise, residual stresses may come up, reducing the ductility of the material. Whereas rolled and welded steel profiles are more suitable for medium and large constructions, cold-formed ones are commonly used in small and medium constructions to compose roof structures, composite slabs and beams, mezzanines, popular houses, small warehouses and up-to-four-storey buildings. In addition, many cross sections are available for design, as C, Z, L and hat, doubled or not, stiffened or not (Silva et al., 2014). One important application of cold formed steel profiles in structural engineering, as presented previously, is in composite slabs. It gets incorporated to concrete after curing, allowing the composite behavior, and works as reinforcement, usually sparing additional ones. Besides, it's necessary to verify the structural safety before concrete curing, in which the steel formwork acts as a single steel beam and must resist to all ultimate limit states that can occur in construction st...

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Resumo Atualmente, com o avanço da tecnologia de corte e solda, perfis de aço com aberturas sequenciais na forma circular, denominados perfis celulares, vêm sendo bastante utilizadas como vigas de edificações. A ABNT NBR 8800:2008 e as normas estrangeiras não abordam vigas de aço e vigas mistas de aço e concreto com perfil celular, o que contribui para que o seu uso seja limitado. Foi desenvolvido e aferido um programa computacional para o dimensionamento de vigas mistas de aço e concreto com perfil celular biapoiadas de acordo com duas metodologias distintas da literatura. Um estudo paramétrico abordando vigas mistas com perfis celulares obtidos de dois perfis I de aço laminados comerciais foi realizado. Nesse estudo, a influência dos parâmetros geométricos do perfil celular e do comprimento do vão da viga na resistência e na forma de colapso foi analisada. Foi possível concluir que em muitas situações o uso de vigas mistas com perfil celular é vantajoso em relação às vigas mistas de alma cheia.

The objective of this article is to present an optimization problem formulation to reduce the total structural cost of prestressed doubly-symmetric and monosymmetric I-shaped steel simply supported beams with straight tendons. The optimization problem was implemented via MATLAB's native Genetic Algorithm. The validation and evaluation processes adopted two examples from literature. The design method follows the Brazilian standard NBR 8800:2008 for the Ultimate and Serviceability Limit States. The best result was found for a monosymmetric case by up to 20.00% and 25.70%. Saving in material weight and installation of tendons, without exceeding the security limits, was also effective. Furthermore, the results presented an efficient alternative for structural engineering, providing a significant model for similar analyzes.