Estudo numérico de ligações tubulares tipo T com reforço de chapa submetidas a esforços normais de compressão no banzo

Abstract

Tubular profiles stand out in the structural engineering scenario because they present geometric properties with high stiffness to compression, flexion and torsion, especially when compared to open-section profiles of the same mass. Furthermore, its wide possibility of use by architects in terms of its aesthetic aspect is a factor that also drives its application in works. Although its applicability in civil construction is relatively recent, its use has been encouraged by the industry in conjunction with the development of academia in providing new guidelines and parameters in the design criteria for these structures. In this context, this work aims to investigate the structural behaviour of T-joint carbon steel tubular connections with SHS profiles, with the brace compressed, with doubler plate reinforcement in the connected wall of the chord and subjected to normal compression efforts. The influence that the doubler plate reinforcement has on the connection behaviour is also investigated, as well as how different thickness levels influence the change in the failure mode of these connections, since the EN1993-1-8 and ABNT NBR 16239 standards ignore the concomitant presence thickness of the chord and reinforcement, only recommending the replacement of one for the other. The numerical models, developed in the ABAQUS software, were calibrated with experimental tests from different researchers, considering different boundary conditions and different geometric properties, increasing the degree of reliability of the results generated. The parametric analysis with 217 models was separated into two stages; the first focused solely on investigating the influence that the reinforcement plate causes on increasing the connection strength, and the second on understanding in which of these models the presence of distinct levels of axial compression effort in the chord causes a reduction in resistance. Combined failure modes were observed, and the von Mises stress level was assessed in these models, always considering the limit deformation criterion to obtain the connection's resistant capacity. The results of the parametric analysis confirmed previous research in which the EN1993-1-8 and ABNT NBR 16239 standards need to be reassessed regarding the strength of connections with reinforcement plates, in addition to the parameter that correlates the tensions in the chord must also be reviewed since the standards lead to results that are contrary to safety in some geometric combinations concerning this parameter. At the end of the research, new formulations with more significant correlations with numerical models are proposed, both for reinforced connections and for the stress coefficient in the chord due to different levels of normal compression stress.