Seismic retrofitting of RC frames combining metallic dampers and limited strengthening with FRP/SRP applying energy-based methods

Strengthening with advanced composite materials (i.e. Fiber Reinforced Polymer laminates, FRP, and Steel Reinforced Polymer spikes, SRP), or adding passive devices (metallic dampers) have been used separately for seismic retrofitting RC frames. On the one hand, using only FRP/SRP may prove insufficient and cost prohibitive. On the other hand, installing hysteretic dampers in an existing frame that lacks a minimum quasi-elastic deformation capacity can jeopardize the efficiency of the metallic dampers, leading to devices of excessive size and cost. This study investigates combining limited FRP/SRP strengthening with the addition of metallic dampers to attain a cost-effective strengthening scheme. This paper elucidates the structural variables involved in such a hybrid solution and the desirable range of their values through an energy-based method. The validity of the proposed method and formulation is assessed through numerical simulations conducted on a RC frame subjected to far-field and near-fault earthquakes.