Análise estrutural de contêineres marítimos utilizados na construção civil

Uma possibilidade para a redução do déficit habitacional ou para a construção de habitações provisórias pode ser a utilização de contêineres marítimos descartados ao fim de sua vida útil na cadeia logística. Pela sua finalidade, os contêineres são estruturas robustas. No entanto, a arquitetura geralmente requer a inclusão de aberturas, a modificação das condições de apoio e o empilhamento dos contêineres, levando a condições de serviço diferentes das originalmente previstas. Este trabalho visa avaliar a influência destas modificações no comportamento estrutural dos contêineres. Para isto foi feita uma análise numérica via Método dos Elementos Finitos no programa comercial SAP2000, considerando aberturas e variações nas condições de apoio sob carregamento oriundo do empilhamento. Os resultados numéricos foram comparados a prescrições de normas brasileiras, e indicaram a viabilidade da utilização dos contêineres na construção civil na maioria das situações. No entanto, a combinação de grandes aberturas e modificações de suas condições de apoio leva a grandes deslocamentos e a elevadas concentrações de tensões, indicando a necessidade da adoção de medidas complementares para assegurar seu bom funcionamento estrutural

Analysis of cold formed structural rack columns.

Este trabalho avalia a ocorr?ncia do modo de associado a flambagem local em pilares curtos constitu?das por perfis formados a frio tipo rack. Estes pilares possuem perfura??es para facilitar a montagem, e este trabalho considera a influ?ncia das mesmas no comportamento e no esfor?o resistente destes perfis estruturais. Os estudos foram realizados por an?lises num?ricas e experimentais, cujos resultados apresentaram boa correla??o e indicaram que as perfura??es n?o afetaram significativamente a carga cr?tica e a capacidade resistente dos pilares, apesar de influenciarem significativamente o comportamento dos mesmos, alterando o n?mero de meias ondas formadas. Observou-se ainda consider?vel influ?ncia das imperfei??es geom?tricas no comportamento da estrutura, indicando a necessidade de sua inclus?o nas an?lises num?ricas.This work presents an evaluation of local buckling in cold formed rack stub columns. These columns have perforations along their length to make assemblage easier, and this research investigates their influence in these structures behavior and resistance. Experimental end numerical analysis were carried out and their results showed good agreement and indicated that perforations in columns don't reduce significantly their buckling load and strength, but affect their buckling modes by changing the number of half waves formed in the columns . It was also observed a considerable influence of geometrical imperfections, indicating the need of their inclusion in the numerical analysis

Cold formed steel semi rigid joints.

This article presents a theoretical and numerical study of an innovative joint using cold-formed steel sections. The motivation for the study of this connection is the ease of manufacturing and assembly that it provides. The profiles are made of coldformed lipped channel sections, which are welded to form closed built-up sections on the columns and open built-up lipped sections to the beams. The beams use endplates connected by bolts (threaded bars) to the columns. The study evaluates the connection?s initial stiffness of 19 models, where the following parameters were varied: the thickness of the profiles and endplates, the height of the column sections and the diameter of the bolts. A theoretical and a numerical study were developed: the numerical study was performed using finite elements through the commercial software ANSYS, whereas the theoretical study was made based on the component method, prescribed by Eurocode 3, that does not include the design of the connection analyzed herein. Thus, aiming to enable the design of joints composed of cold-formed lipped channel sections, the analysis results were compared and an adjustment coefficient, proportional to the slenderness of the column?s plates, was proposed. The coefficient was introduced to the stiffness component that represents the column web in compression in the mechanical model. The ratio between the coefficients? numerical and theoretical values presented a maximum variation of 11%, which was considered satisfactory

Numerical analysis of T joints with hollow sections.

Neste trabalho ? apresentada uma an?lise param?trica de liga??es soldadas do tipo T formadas por perfis estruturais de a?o sem costura, com se??o transversal retangular no banzo e circular no montante. Um modelo num?rico foi calibrado com resultados experimentais e ap?s a calibra??o foi feito um estudo param?trico variando os par?metros ? (rela??o entre o di?metro do montante e largura da face banzo conectado) e 2? (rela??o entre a largura e a espessura da face do banzo). Os resultados dos modelos num?ricos, obtidos pelo crit?rio de deforma??o limite, foram comparados com as prescri??es mais recentes da ABNT NBR 16239 (2013) e da ISO 14346 (2013).This work presents a parametric analysis of T welded joints formed by hot?rolled steel, with rectangular hollow sections for the chord and circular hollow sections for the braces. A numerical model was calibrated with experimental results and after the calibration a parametric study was performed, varying the parameters ? (ratio between the diameter of the brace and width of the chord) and 2? (ratio between the width and thickness of the chord). The numerical results, obtained using the deformation limit criterion, were compared with the normative prescriptions of ABNT NBR 16239:2013 and ISO 14346:2013

Analysis of the distortional buckling mode of perforated elements using the direct strength method.

Este trabalho apresenta um estudo te?rico e num?rico da influ?ncia de perfura??es no comportamento e capacidade resistente de pilares em perfis formados a frio submetidos a compress?o. Pilares com diferentes se??es transversais e perfura??es foram avaliados numericamente via ANSYS e GBTul, com ?nfase no modo de instabilidade distorcional. As for?as ?ltimas da an?lise num?rica foram comparadas ?s equa??es do M?todo da Resist?ncia Direta (MRD) da ABNT NBR 14762:2010. Finalmente, foram propostas adequa??es ?s equa??es do MRD para possibilitar o dimensionamento de pilares que apresentam se??es com a tipologia de perfura??es estudadas.This work presents a theoretical and numerical study on the influence of perforations on the behavior and strength of cold?formed steel columns subjected to compression. Members of different cross?sections and perforations were evaluated numerically via ANSYS and GBTul, with emphasis on distortional buckling mode. The ultimate loads of the numerical analysis were compared to the Direct Strength Method (DSM) equations of ABNT NBR 14762:2010. Finally, changes were proposed in the DSM equations so it is possible calculate the predicted compressive strengths of columns with perforated cross?sections studied

Numerical analysis of truss systems with stiffened flattened end-bars.

Circular hollow sections are usually used in long-span roof truss systems. One of the typology for connecting elements in such structures involves the flattening of bar ends. This article presents the numerical analysis of a plane truss composed of circular hollow sections, in which diagonal bars have flattened ends. In this sense, a new flattening typology called stiffened flattening is proposed, characterized by a non-flat geometry, with the creation of stiffeners in the lateral edges of the diagonal flattened ends. The diagonal connecting system with the chord members uses connecting plates. The plates are welded to the chords and the diagonals are connected to latter through a single bolt. The numerical analysis using finite elements method was developed in two stages through ANSYS software with the Parametric Design Language (APDL), in which parameters such as geometry, materials, element types, boundary conditions and loads are specified. A non-linear analysis was performed using shell elements on the chords, diagonals, plates and welds, and contact elements between the diagonals with stiffened flattened ends and the connecting plates. Initially, a numerical study of the connecting node and the stiffened flattened end was performed, and the results directed the modeling of the plane truss. The numerical results were calibrated with the experimental truss results in full scale. The numerical result of the plane truss was also compared to a theoretical study, considering the axial load eccentricity applied in the diagonal with stiffened flattened ends. The study was based on the consideration of combined effects of axial force and bending moment provided by the Brazilian standard ABNT NBR 8800:2008. The final results indicate that the numerical model proposed is efficient and has good correlation with the experimental and theoretical results

An?lise experimental de um conector mec?nico de cisalhamento em pilar misto de a?o e concreto.

Este trabalho compreende um estudo anal?tico e experimental do comportamento estrutural de conectores de cisalhamento em pilares mistos, formados por perfis tubulares laminados de se??o circular de a?o preenchido por concreto simples. Para este estudo foi adotado um conector do tipo parafuso estrutural, a fim de verificar a validade das express?es anal?ticas constantes na ABNT NBR 16239:2014 [1]. Foi realizada uma s?rie de ensaios experimentais de cisalhamento direto, fixando o di?metro externo do tubo e variando a espessura, o di?metro do parafuso, a resist?ncia do concreto e a presen?a ou n?o de folga no furo. Da an?lise dos resultados observa-se que ? vi?vel a utiliza??o desse tipo de conector, que as equa??es existentes para o dimensionamento dos mesmos est?o a favor da seguran?a e podem ser ajustadas para fornecer valores de capacidade resistente mais pr?ximo do experimental.This work includes an analytical and experimental study of the structural behavior of shear connectors in composite columns, composed of concrete-filled circular hollow section. For this study was adopted a structural bolt like a shear connector in order to verify the validity of the analytical expressions in ABNT NBR 16239: 2014 [1]. Was carried out a series of push-out tests, fixing the outer diameter of the hollow section and varying the thickness, the bolt diameter, the strength of concrete and the hole dimension. Analysis of the results shows that is possible to use this type of shear connector. The Brazilian prescriptions results are conservative and may be adjusted to provide strength capacity value closest to the experiment

Reliability of steel beams designed by Brazilian code NBR 8800.

O estudo da confiabilidade estrutural se relaciona com a avaliação da probabilidade de violação dos estados limites para um sistema estrutural. Uma vez definidos pelo projetista os estados limites relevantes ao sistema estrutural, deve-se calcular o nível de segurança com respeito a esses estados. Nesse trabalho, é feito um estudo do nível de confiabilidade de vigas de perfis I laminados para o estado limite de flexão, projetadas segundo a Norma Brasileira NBR 8800 (1986) e seu projeto de revisão NBR 8800 (2003) através do método de confiabilidade de primeira ordem (FORM). São apresentados gráficos das variações do índice de confiabilidade (β) em função do índice de esbeltez e, em seguida, é apresentada uma metodologia para uniformizar a confiabilidade, no domínio de um estado limite, através da adoção de procedimentos de correção do coeficiente de resistência.The study of structural reliability is related to the assessment the probability of limit state violations in a structural system. Once the designer defines the relevant limits of the structural system, the safety level of these limits must be evaluated. A reliability study of hot-rolled I beams in a flexure limited state, designed in accordance with Brazilian Code NBR 8800 (1986) and draft of new NBR 8800 (2003) was done by the First Order Reliability Method (FORM). Variations of the reliability index (β) versus slenderness are plotted, and finally a methodology to obtain uniform reliability in a limitedstate domain by adopting correction procedures for the strength factor is presented