Optimal distribution of connections with dampers to improve the performance of steel rigid frames

To reduce the seismic response of steel frames, energy dissipation devices can be placed at connections. These connections can be modeled as a rotational spring and damper in parallel. In this paper, an attempt is made to estimate the best distribution of the connections, by time-history analysis and optimization operation. Although in the previous studies, these connections were distributed uniformly, in this research the combination of these connections in rigid frames is proposed. Two 9 and 20-story frames with sections and dimensions based on SAC benchmark structures are studied. Seismic performance of optimized structures with connections equipped with dampers and rigid connections is evaluated and compared with that of the moment frame with uniformly placed such connections. It is observed that performance of hybrid structures, despite having less dampers in connections, is much better than the structure with uniform distribution of this type of connections. On the other hand, linear and nonlinear behavior of elements and connections in structure is developed. Also, in optimal condition, 62 and 68% of the connections in linear and 58 and 61% in nonlinear behavior have been equipped with dampers respectively for 9 and 20-story structures.