Seismic performance of steel structures with seesaw energy dissipation system using fluid viscous dampers

This paper presents a new vibration control system based on a seesaw mechanism with fluid viscous dampers. The proposed vibration control system comprises three parts: brace, seesaw, and fluid viscous dampers (FVDs). In this system, only tensile force appears in bracing members. Consequently, the brace buckling problem is negligible. This benefit is useful for steel rods for bracing members. By introducing pre-tension in rods, long steel rods are applicable for bracing between the seesaw members and the moment frame connections over several stories. The relation between the frame displacement and the damper deformation is first derived in consideration of the rod deformation. Simplified analysis models of seesaw energy dissipation system are developed based on this relation. Subsequently, seismic response analyses are conducted for three-story and six-story steel moment frames with and without dampers. In addition to the proposed system, a diagonal-brace-FVD system and a chevron-brace-FVD system are analyzed for comparison. Parameter analyses of rod stiffness and damping coefficient are conducted for the six-story frame. The maximum story drift angle and response of the top floor displacement are discussed. Results show a high capability of seesaw energy dissipation system for improving the structural response.