Seismic protection of structures by smart passive control system using “regional algorithms”

The possibility of reducing structural response under external excitations such as earthquakes and wind storms via control systems is attracting the interest of a large number of researchers. In the field of civil structures, control systems based on semi-active (SA) devices seem to be close to feasible implementation. Semi-active devices are typically passive elements capable of self-adjusting their own mechanical properties according to the instantaneous response of the hosting structure and, therefore, they can be considered as smart devices. Dampers based on magnetorheological fluids are considered very effective in practical implementations. This paper aims to show the potential of such devices to reduce the seismic response of structures exploiting some information provide by a seismic early warning system (SEWS). Current research on SEWS include the anticipate estimate of the peak ground acceleration (PGA) of the incoming earthquake. The paper focuses on the control algorithm needed to select the optimal voltage to set the variable devices according to the PGA estimate. The authors found that the different characteristics of earthquakes, that occur on different sites, such as frequency content, duration and magnitude, play a significant role in the definition of the best control algorithm. For this reason, a regional control algorithm has been built for each of three selected worldwide regions (Japan, California and Italy).