Avaliação da influência de tensões normais no banzo para a resistência de ligações soldadas entre perfis RHS e SHS

Abstract

The adoption of hollow section profiles in steel structures has stood out, especially, due to its high resistance to compression, torsion, bending and combined loads. Therefore, they are widely used in columns, trusses and bracing elements. In light of this context, it is necessary to expand studies in the area, aiming to achieve the best form of application of this profile as structural elements. A particularly important aspect in the design of tubular structures is the assessment of the joints, since these points are susceptible to different failure mechanisms. Traditionally, this evaluation is carried out based on technical standards, such as Eurocode 3, part 1-8, ABNT NBR 16239 and ISO 14346. The objective of this dissertation is to develop a numerical study, evaluating the effects of chord stresses on the ultimate resistance of welded joints constituted by SHS and RHS cold-formed profiles, with β ratio equal to 1. A parametric analysis was conducted with finite element models elaborated in the software ANSYS, and calibrated against experimental results. In this analysis, unreinforced and reinforced T tubular joints were simulated, considering different levels of chord axial preloading. From the results, it was observed that the introduction of compression and chord tension loads reduces the joint ultimate capacity. A greater resistance reduction is noted for joints with chords subjected to tension loads. With the inclusion of sidewall reinforcement plates, it was verified a lower ultimate resistance decrease, indicating that the effects of chord axial stresses is more significant in unreinforced joints than in reinforced joints. Finally, it was concluded that ISO 14346 function Qf, which introduces the effect of chord axial stresses into the resistence capacity of welded tubular joints, was the one that presented the best results, however it provided overestimated values for a wide range of joints with chord subjected to tension loads, and for this reason, two new methods are proposed conducting to satisfactory results.