Análise teórico-numérica da influência do número de parafusos no comportamento de cantoneiras laminadas de aço comprimidas concêntrica e excentricamente

Abstract

Hot-rolled steel single angle sections in compression are used in various structural systems. In most of the practical cases, these members are attached to others only by one leg, usually by bolts. This type of connection results in an eccentric compression of the angles, which, allied to their peculiarities such as low torsional stiffness and rotation of the principal axis in relation to the legs, makes their analysis and their design complex tasks. Currents codes provide a simplified procedure for angles in compression, in which eccentricity effects are accounted for by using an equivalent buckling length. Then, calculations are performed as if the members were subjected to concentric compression, with the buckling elastic loads determined from the geometric properties with respect to the axis parallel to the connected leg or minor principal axes. However, this procedure can lead to discrepant results for ultimate compressive strength of steel angles. The objective of the present work is to study the behavior of hot-rolled steel single angles in concentric and eccentric compression. To achieve this objective, an evaluation of the influence of the number of bolts on the compressive capacity was performed using analytical formulations and numerical analyses. The results of these analyses were compared with American, European and Brazilian codes. This comparison showed great agreement of the codes procedures with the numerical results for concentric compression, but considerable divergences were noted in the evaluations for eccentric compression. Thus, an adaptation in the design methodology of the ABNT NBR 8800:2008 code for angles in eccentric compression was proposed and had its validity assessed, presenting great suitability for the main commercially sold angles.