Optimal Stiffeners Spacing for Intermediate Link in Eccentrically Braced Frame to Increase Energy Dissipation

In general, the behavior of an eccentrically braced frames (EBF) is dependent on the link member characteristics. An efficient link is designed ductile enough to dissipate energy and to prevent the collapse of the frame. Since the link member is reinforced with stiffeners, in order to improve its ductility and plastic deformation capacity, the details of stiffeners design shall be considered more precisely. The existing relationships for web stiffeners spacing in the provisions are based on the behavior of short links with pure shear, while these relationships are applied for intermediate links with shear-bending behavior as well, without any modification. Recent studies have shown the non-conservative stiffeners spacing for some intermediate links. In this study, an optimization algorithm is presented to find the best arrangement of the intermediate link stiffeners. The objective function is the plastic dissipated energy by link before failure and the design variables are locations of stiffeners. The link is simulated under static cyclic loads with finite element software ABAQUS. The heuristic optimization algorithm has been coded in the MATLAB software to find the optimum solutions. The results show that the dissipated energy before failure can be improved significantly by modification of stiffeners spacing.