S Ebrahimi - PHD Student in Earthquake engineering, Tehran University, Tehran, Iran
H Shakib - Professor, Tarbiat Modares University, Tehran, Iran

Eccentrically braced frames (EBFs) by covering the advantages ofmoment-resisting frames (MRF) and concentrically braced frames (CBF)have been used as seismic load resisting systems in buildings for more thanthree decades. In eccentrically braced systems, failure and yielding shouldhappen in the links, and other members of the structure must remain inelastic behavior, therefore, links are so important.In this investigation, the effect of link section and its stiffeners ondisplacement demand of EBFs has been studied. In this study, ٦-storiesEBFs with three different lengths of links (shear, intermediate andflexural), two different cross-sections (tubular and I-shaped) under theinfluence of three records (Landers, Northridge and Tabas) have beenstudied and their displacement demands have been compared together. Itshould be noted that links with tubular and I-shaped cross-sections aresimilar in area, moment of inertia and length.In this investigation, EBFs have been modeled in ABAQUS. In thesemodels, sell elements have been used for links and beam elements havebeen used for others. Nonlinear kinematic hardening plasticity model hasbeen used for the materials and in order to loading, scaled records havebeen imported to the frame bases.The result of this investigation indicates that displacement demand of EBFswith I-shaped links is less than displacement demand of EBFs with tubularlinks. This decreasing is approximately ٢٤٪. The preference of I-shapedlinks to the tubular links is because of I-shaped links' web is surroundedfrom up and down by flanges and from around by stiffeners in both sides,leading to creation of clamped boundary conditions around the web. Buttubular links' web is surrounded from up and down by flanges and from around by stiffeners in one side. In this state, simply supported boundaryconditions are created around the web.

Displacement demand, Link, Stiffener