EM - Escola de Minas

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Bearing failure in bolted sleeve connections with circular hollow sections under compression.
(2020) Oliveira, Matheus Miranda de; Amparo, Lucas Roquete; Sarmanho, Arlene Maria Cunha; Pereira, Daniel José Rocha; Alves, Vinicius Nicchio
This article analyzes sleeve connections between circular hollow sections. This type of connection is composed of two tubes connected by bolts to an inner tube with a smaller diameter, and explores the efficiency, aesthetics and resistance of hollow sections subjected to tension and compression. In previous researches, sleeve connections with aligned and crossed bolt dispositions and under axial tension were studied. Herein, the behavior of sleeve connections with aligned bolts and under compression was analyzed. A model to represent the connection using the finite element method was developed, which allowed a numerical analysis with geometric property variations. In the numerical/parametric results, bearing failure was observed in all cases, either in the outer or inner tube. Limiting the number of bolts to 6 and considering that connections have a lower outer thickness than the inner tube, a formulation was proposed to determine the ultimate bearing capacity of sleeve connections under compression and with bearing failure.
Numerical analysis of truss systems with stiffened flattened end-bars.
(2018) Mazon, Ana Amélia Oliveira; Sarmanho, Arlene Maria Cunha; Nunes, Gabriel Vieira; Amparo, Lucas Roquete; Neiva, Luiz Henrique de Almeida; Souza, Flávio Teixeira de
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.
Behavior analysis of bar gaps in welded YT-joints for rolled-steel circular hollow sections.
(2010) Vieira, Rosilene de Fátima; Requena, João Alberto Venegas; Sarmanho, Arlene Maria Cunha; Arcaro, Vinicius Fernando
We present a parametric analysis of gap variation between the lap brace and through brace of YT welded joints for rolled-steel circular hollow sections on plane steel structures. Our aim is to investigate the collapse behavior of YT-joints under lap brace axial compression. In particular, we focus on e/d0 ratios above 0.25 so bending moments can be taken into account during the design. We find that joint failure is primarily due to chord wall plastification (Mode A) and cross-sectional chord buckling (Mode F) in the region underneath the lap brace. Our joint design followed the Limit States Method, and our results were based on a comparative analysis of three different methods: an analytical solution derived from a set of international technical norms, an experimental analysis, and numerical modeling using Ansys as calibrated by our experimental results.

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