Optimal distribution of damping coefficient of viscous dampers in steel structures based on performance index

Viscous dampers are one of the passive control systems that reduce the seismic demand of the structural elements of a building and minimize the building damage. However, the proper arrangement of viscous dampers greatly affects their increased performance, and it is not economical to use viscous dampers in all floors. In this study, the viscous dampers are designed according to four distribution methods based on FEMA 356: uniform damping coefficient distribution, distribution proportional to shear force of floors, distribution based on shear strain energy of floors and distribution based on shear strain energy of effective floors. In order to find the optimal distribution method, the seismic responses of the structure including the maximum drift ratio, maximum relative acceleration of floors, and strain energy are extracted and the results obtained from the rehabilitation in the four methods are compared with the proposed performance indices. Considering the effect of each method of damping coefficient distribution on the structural performance indices, it can be argued that the damping coefficient distribution based on the effective floors has a more appropriate performance compared to other methods of damping coefficient distribution. The results of time history analysis show that the viscous dampers used in the benchmark buildings cause a 50% improvement in the performance index of mid- and high-rise structures and also a 40% improvement in the force index of mid- and high-rise structures under the far-field acceleration.