Optimum design of structures using viscoelastic dampers for static and earthquake loads

The ability of engineering structures to survive earthquake ground motions without major damage depends largely on their energy dissipation capacity. Traditionally, a structure has to be designed to go through inelastic deformation, through which energy will be dissipated. The amount of energy dissipated will depend on the size and stability of the hysteresis loops of the force-deformation behavior of the structural members and their connections. While this inelastic action may be able to dissipate large amounts of energy, it often results in significant damage, and the hysteretic behavior will degrade with repeated inelastic cycling. Also, the interstory drifts needed to achieve significant energy dissipation are normally large and will result in damage to non-structural elements such as partitions, doorways, infill walls, and ceilings.; To overcome such shortcomings, new concepts of earthquake resistant design can reduce the structural damage under seismic excitations. These new concepts include active and passive control systems. Adding such devices which are known as energy absorption systems can reduce the vibrational response of the structure by dissipating the input energy into the surrounding in the form of heat. While viscoelastic dampers have been successfully used in several high-rise buildings for their wind resistance, their effectiveness in enhancing the structural earthquake resistance is being investigated in this study.; While most previous studies of earthquake-resistant design were confined to traditional design methods and to the small damping inherent in the structure, this study is concerned with optimum design of structures with added viscoelastic dampers to ensure both safety and economy. The optimum design process will be achieved by using the optimality criteria method which is considered very efficient for solving large engineering problems.; A design algorithm has been proposed for optimum design of structures with added viscoelastic dampers. Two different design alternatives and a case study are being investigated in this study. Structural displacements, drifts, and ductility demand on the structural members were reduced greatly. In the case study, the structural weight was reduced largely due to added viscoelastic dampers. While both design alternatives showed safe and acceptable designs, design alternative 1 showed less ductility demand on the structural members. Comparison between the structural response and ductility demand on the structural members is also being investigated. Finally, structural response by including and neglecting the damper stiffness is being studied.