A simple approach for optimal allocation of dampers in nonsymmetrical 3D multi-storey structures

A new simple approach is proposed to search for the optimal placement of dampers in nonsymmetrical three-dimensional (3D) structures. Dampers are placed uniformly and initially at each storey of two selected bays of the bare structures and the time-history seismic analysis is performed. The maximal inter-storey drift ratio is chosen as the performance index. Then the inter-storey drift ratio is checked for the locations where dampers were added. The damper in the location with the minimal inter-storey drift ratio is moved to the location having the maximal inter-storey drift ratio. This process is repeated until the prescribed stop criterion is met. Both linear and nonlinear viscous dampers are used in this study. The damping coefficient of added dampers for the initial damper placement is determined by setting the maximal inter-storey drift ratio of the whole structure equal to a certain value when a ground motion is applied. In the proposed relocation process, the maximal inter-storey drift ratio will be reduced significantly. Three examples, including two 10-storey and one 20-storey 3D nonsymmetrical structures, are used to demonstrate the efficiency and accuracy of the proposed approach. The results are compared with those obtained using the simplified sequential search algorithm (SSSA). It is found that the proposed approach requires fewer number of time-history analysis than that using the SSSA while their accuracy is comparable.