عنوان مقاله [English]
The strength and stiffness of an eccentrically braced frame (EBF) can be similar to a concentrically braced frame, while simultaneously its energy dissipation capacity can be same as a moment resisting frame. In EBF, strength and stiffness are provided by braces and ductility and energy dissipation by link. Therefore, link beam is one of the most important key factor in the seismically response of EBF. In the strong earthquake, link beam is passed into the plastic zone and causes the other frame components remain elastic. In general, behavior of EBF is dependent on the link member design. Therefore it must be ductile enough to dissipate energy and prevent the collapse of frame. The link member is reinforced with stiffeners. The stiffeners delay local buckling of flange and increase cyclic ductility of the beam. Existing provisions for stiffeners design are developed based on short link beam behavior (shear behavior), and there are used for intermediate and long link beams regardless of bending considerations related to these types of link beams. In this paper, effects of geometrical properties of stiffeners and also link beam section are investigated for long, intermediate and short link beams. For this purpose, 25 link beams with different sections and lengths are simulated under static cyclic load by finite element software ABAQUS based on AISC seismic provisions. As a result, effects of different geometrical properties are discussed and suggestions for improving the energy dissipation of link presented. The results show that stiffeners tend to move towards the ends in the intermediate link beam and one of the stiffener can be removed in the short link beam. The stiffener thickness can not have a significant impact on the seismic response of link beam, while the efficient arrangement of stiffeners depend on the ratio of width to depth of beam section in long and intermediate link beams.