Effectiveness of different distributions of viscous damping coefficients for the seismic retrofit of regular and irregular RC frames

•Different distributions of viscous damping coefficients are investigated.•Simple distributions are compared with two energetic methods and SSSA algorithm.•Five regular and irregular RC frames retrofitted with viscous dampers are studied.•The effectiveness of the methods is verified through nonlinear dynamic analyses.•Several parameters are examined, as interstorey drifts and maximum damper forces.

The main purpose of this research has been to investigate the effectiveness of different vertical distributions of the damping coefficients of nonlinear viscous dampers for the seismic retrofit of existing multi-storey reinforced concrete frames. In particular, different simple distributions were compared with other procedures proposed in literature, including two energy methods and a repetitive simplified sequential search algorithm. The effectiveness of the different distributions was then examined by performing time-history analyses and considering a nonlinear behaviour for both the viscous dampers and the structural members. The structures being considered are five RC frames with a different number of storeys and both regular and irregular configurations in elevation. The results of the nonlinear dynamic analyses were examined in terms of maximum and residual interstorey drifts, peak floor accelerations and maximum damper forces. The energy methods, in particular, provided good results in terms of reduction in cost, efficiency of the distribution and simplicity of application, compared to other effective, but more complex methods.