Seismic performance of semi-continuous steel frames with nonlinear viscous dampers

In the paper, the seismic performance of steel frames equipped with nonlinear viscous dampers is analysed and a practical design approach is presented. The proposed strategy is tailored to design new seismic resistant structures or improve the response of existing frames, where the use of nonlinear fluid viscous dampers allows a significant reduction in structural damage and lateral displacements under earthquake loading. The effectiveness of the proposed design procedure is checked considering the results of nonlinear dynamic simulations. In the numerical description for steel frames, beams and columns are modelled using plastic beam elements and nonlinear rotational springs are employed for representing the hysteretic behaviour of beam-to-column connections. The numerical outcomes confirm that the use of nonlinear viscous dampers guarantees not only a limited interstorey drift demand and a reduced plastic damage in the frame but also no increase in base shear.