EXPERIMENTAL AND ANALYTICAL STUDY OF STEEL YIELD DAMPER WITH THE AIM OF IMPROVING ITS SEISMIC PERFORMANCE

Dampers are a suitable choice to improve structural performance and protect structures against lateral loads, including seismic excitements. A steel slit damper (SSD) is a damper that can be replaced after major earthquakes. After reviewing literature on the metallic yielding dampers, this paper tried to identify the behaviors of such dampers in order to find approaches that are suitable for improvement and/or optimization of such dampers by increasing the number of blade rows and introducing a new geometric pattern. This study designed, fabricated, and examined a total of seven laboratory samples, including a solid damper without slit or blade as the reference, three slit dampers with a single blade row, as well as three slit dampers with two blade rows, which were subjected to static cyclic loading in laboratory. Results showed that a shift from bending towards shear behaviors can increase energy dissipation by the damper. In addition to the behavioral shift, the displacement capacity of damper partially reduces. To prevent the reduction of displacement capacity and achieve higher level of performance, dampers should be designed with two or more blade rows. The experimental observations showed that the stiffness of dampers with two blade rows is approximately twice the dampers with a single blade row; in addition, their effective damping was nearly 1.25 times higher. In addition to experimental results, different parameters, such as force capacity, effective stiffness, and dissipated energy, were calculated and compared. Results showed that the force capacity, effective stiffness, and absorbed energy were significantly better in dampers with two blade rows. In that, the difference between these two dampers in terms of the force capacity was 61.6%. Regarding the superiority of dampers with two blade rows and observation results, the optimal ratio of blade length to width (h/b) to prevent buckling in the samples was estimated at 1.58.