Abstract The circular hollow sections (CHS) are being widely employed in steel structures around the world, increasing the development of new researches. This article proposes an innovative connection model for circular hollow sections that facilitates and reduces the assembly cost of hollow section structures. The proposed connection is a tube sleeve, used to splice two tubes, composed of an inner tube with a diameter smaller than the connecting tubes, which is connected to the outer tubes by bolts passing through both tubes. This connection can be a cheaper and easier alternative to flange connections, which are widely used in large span tubular trusses. The connection was tested in laboratory under tension loading. The tests made it possible to identify the influence of stress distribution on tubes and the need for the use of a shear lag coefficient. The results of the ultimate load capacity demonstrated the viability of the tube sleeve connection use.

Abstract Herein is presented a numerical methodology for a static resistance analysis of symmetrically loaded multiplanar KK joints in circular hollow steel sections. This methodology addresses factors related to the simulation of KK joints such as the material properties, the boundary conditions, mesh generation and refinement, incremental load steps and failure criteria. An objective criterion is proposed to identify the two failure modes most often occurring in KK joints. Failure mode 1 is observed when two neighboring diagonal braces loaded in the same sense act as one brace penetrating the chord together. In the failure mode 2, excessive deformation is observed in the chord region between two neighboring braces, folding the chord wall. However, in some cases the failure mode is not easily identified or both failure types are present. The proposed criterion objectively identifies the failure mode. In order to compute the joint resistance, an important failure criterion often adopted in literature for uniplanar K joints is the one known as Lu's deformation. In this paper, a strategy is proposed, which is an extension of Lu's criterion for multiplanar KK joints.

O objetivo desse trabalho foi avaliar, através de cálculo analítico e modelagens elástica bidimensional e plástica tridimensional, a capacidade resistente e o modo de ruptura de treliças tubulares mistas biapoiadas com 15 metros de vão, variando-se o número de painéis Vierendeel centrais. O estudo apontou a proporção vão/3 - vão/3 - vão/3 como a ideal para a relação entre trechos treliçado - Vierendeel - treliçado, pois, ao se aumentar a proporção do trecho central, ocupado pelos painéis Vierendeel, os novos sistemas perdem muita rigidez, passando a não suportar mais a carga estipulada em projeto. Além disso, podem passar a apresentar deslocamentos verticais excessivos e resistência às forças cortantes externas atuantes sobre os painéis insuficiente.

The aim of this study was to evaluate through analytical calculation, two-dimensional elastic modeling, and three-dimensional plastic modeling, the bearing capacity and failure modes of composite hollow trusses bi-supported with a 15 meter span, varying the number of central Vierendeel panels. The study found the proportion span/3 - span/3 - span/3, as the ideal relationship for the truss - Vierendeel - truss lengths, because by increasing the proportion of the length occupied by the central Vierendeel panels, the new system loses stiffness and no longer supports the load stipulated in the project. Furthermore, they can start presenting excessive vertical displacements and insufficient resistance to external shear forces acting on the panels.

O objetivo desse trabalho foi desenvolver um sistema de cobertura metálica padronizado e modular, utilizando perfis tubulares laminados sem costura. Esse sistema se destina, principalmente, a coberturas de supermercados, shoppings etc., que necessitam de grandes áreas livres. Para se avaliar o comportamento estrutural desse sistema, foi construído, de maneira inédita no Brasil, um protótipo de 900 m², para testar o sistema construtivo idealizado e realizar ensaios com os carregamentos reais, nesse tipo de estrutura. Avaliando-se, então, o comportamento global da estrutura, com base em todos os resultados numéricos e experimentais obtidos, confirmou-se o comportamento previsto, no cálculo computacional, com o protótipo ensaiado.

The purpose of this study is the comparison between experimental and numerical data of a roof system made of tubular steel sections. Such roof system is applied mainly for supermarkets, large stores and industries. To evaluate the structural behavior of this system, a 900m² prototype was built, - an unprecedented opportunity in Brazil to accomplish experimental tests with usual loads for this type of structure. Evaluating the behavior of the entire structure, with all the results obtained on experimental tests and numerical analysis, it was concluded that the prototype is in general accordance with the designed model in terms of stresses and displacement.

É apresentado, nesse trabalho, um programa de computador (AutoTorre 1.01) para automação do projeto de torres metálicas autoportantes, para telecomunicações, utilizando perfis tubulares. O objetivo do programa é auxiliar e facilitar o desenvolvimento e a análise do projeto estrutural de torres, utilizando as normas brasileiras para o cálculo das ações de vento estática e dinâmica e, para o dimensionamento das barras. Assume-se que os cálculos de ações de vento, obtenção dos esforços e dimensionamento das barras envolvem esforço repetitivo e por isso, devem ser automatizados, dando ao calculista maior tempo para reflexão geral do projeto. As funcionalidades do programa contemplam a automação da geometria e das ações de vento, o cálculo dos esforços, o dimensionamento das barras e o cálculo do período fundamental de vibração da estrutura (análise modal), além de uma interface gráfica amigável para o usuário. São comparados os resultados das ações de vento calculadas estática e dinamicamente, segundo a NBR6123, e os resultados da escolha do método estático ou dinâmico para o cálculo das ações de vento, resultando em uma estrutura segura e econômica.

In the present work, introduced is a software (AutoTorre 1.01) to design steel telecommunication towers using hollow sections. The main purpose of the software is to help and assist the engineer in the process of analyzing and designing a steel tower. The software uses Brazilian specifications to compute wind loads and design beams. The calculation of wind loads, structure efforts and beam design is mechanical work that has now been automated and thus saves time for the engineer and allows for focus on other important aspects. Software routines allow the user to generate automatically the tower geometry, compute wind load and design the beams. Another functionality consists in a modal analysis to obtain the fundamental period of vibration. The software has a friendly graphical user interface. Wind load results according to two methods (static and dynamic methods) proposed by the NBR6123 are compared, to obtain a safe and economic structure.