High-efficiency amplifiers for viscous damped structures subjected to strong earthquakes

Amplifying devices increase the displacements and the velocities that are transferred to the dampers attached to them, enabling the use of viscous dampers with lower damping coefficients in order to achieve optimal structural behavior. A known design algorithm for such devices simplifies the real behavior of the amplifier by assuming small displacements and velocities, which are transferred to the damper. This algorithm is likely to be less effective under strong earthquakes that induce large displacements and velocities. This paper discusses high-efficiency amplifiers that have large amplifying ratios and proposes an improved method, which takes into account more accurate values of the displacements and velocities transferred to the damper, in order to obtain an enhanced structural response to earthquakes. The efficiency of the proposed method is demonstrated in a numerical simulation of a shear framed eight-story reinforced concrete viscous damped structure. The simulation compares the behavior of the structure designed according to the simplified and to the proposed algorithms. It shows that for relatively large amplifying ratios and for drifts induced by strong earthquakes the proposed methodology yields better results.