Avaliação do comportamento de chapas enrijecidas por múltiplos enrijecedores longitudinais

Abstract

The use of welded steel girders with slender web plates is an efficient solution, especially to constructions in which the main goal is to overcome large spans, such as bridges. However, due to the slenderness of some elements, this structure is susceptible to instability problems, making it essential to use stiffeners to increase buckling resistance capacity. This increase depends mainly on the position and flexural rigidity of the longitudinal stiffeners. The standard EN 1993-1-5:2006 and the computer program EBPlate 2.01 present procedures widely used in practice to obtain these critical stresses. As in most academic research on the area, the analyses are usually performed considering panels with all 4 edges supported. However, some authors claim that in cases of I-section girders, the consideration of simple support at the longitudinal edges to represent the constraints provided by the flanges leads to conservative results. In this sense, the present paper studied, using the ABAQUS program based on Finite Element Method, the buckling behavior of stiffened slender plates in order to understand the influence of the aspect ratio and the amount, position, and flexural rigidity of the longitudinal stiffeners on the phenomenon. For this purpose, supported panels were considered and submitted to the isolated action of shear and different ratios between normal stresses and the interaction of bending and shear. Finally, the optimum position and the minimum flexural rigidity of the longitudinal stiffener were determined. Some of the results obtained were compared with the values found using the European standard and EBPlate 2.01, and an initial study was performed to understand the influence of flanges constraints on I-girders. It was observed that the flexural rigidity of the stiffener is one of the parameters with the greatest impact on buckling behavior, and an increase of up to 557% was found for the critical stress in cases where the rigid stiffener is positioned in the optimal position. In the standard and in EBPlate 2.01, the increase in stresses was also noted as the flexural rigidity of this element increases. Furthermore, the interference of this parameter in the results of the influence of the restrictions imposed by the flanges on the web in I-girders was also observed.