Avaliação estrutural de ligação tubular tipo T bird beak diamond em aço inoxidável

Abstract

Tubular steel structures have gained wide recognition in the field of civil engineering over the decades due to their distinct characteristics compared to open cross-sectional profiles such as angles, I-beams, among others. Tubular structures exhibit better structural behaviour, especially when subjected to compression, torsion, and bending loads. Additionally, the closed-section shape, without sharp corners, reduces the surface area to be protected and extends the life of corrosion protection. Several studies have been conducted to optimize designs and structures, and in this context, bird beak diamond connections, where the brace and the chord are rotated 45° around their axis, and structures in stainless steels are promising solutions due to their higher ductility and corrosion resistance. Many studies have been developed on tubular connections in carbon steel, but there is a significant scarcity of studies that adequately address tubular connections in stainless steel. Bird beak connections aim to optimize structures, seeking to achieve higher resistances with the same profile. Meanwhile, stainless steels, due to their greater strength and capacity gain with increasing deformation, have also become an interesting option. This study investigates, through numerical analysis, the behavior of bird beak diamond connections in stainless steels, with β=1, comparing three types of stainless steels: austenitic, ferritic, and lean duplex. The numerical models were developed using the finite element program ABAQUS version 6.14 and were calibrated with experimental tests performed on carbon steel. Since there is no formulation in the standards for this type of connection, the results were compared with formulations proposed in the literature for other types of steel. For the three types of materials, the proposed formulations were found to be very conservative. Two new formulas were developed for the design of bird beak diamond connections in stainless steels with β=1, based on formulas proposed in the literature, aiming to achieve more consistent responses with the results obtained in the parametric analysis and providing good results for predicting the strength of these connections. Austenitic and ferritic steels showed similar strengths by the ultimate deformation criterion; however, as the deformation increases, austenitic steel shows superior strength gain over ferritic steel. Lean duplex steel showed superior strengths in all cases.