Experimental validation of novel friction damper for anti-seismic control of civil structures

This work presents a new semi-active friction damper device, based on piezoelectric technology, for the anti-seismic control of civil structures. A civil structure, representative of a two storey steel framed building, and a reference seismic excitation signal were used to size the semi-active friction damper. Matlab-Simulink based software (EarthSim) was implemented to simulate the response of the steel frame to the seismic excitation, applied at the base of the structure. The dynamic response was evaluated both in the case of the active device (controlled response) as well as the non-active device. Different configurations (in terms of the device’s overall performance and control algorithm parameters) were simulated for the active control system. In so doing, a reference configuration for the structural control system was determined by identifying optimal values for control logic parameters, as well as for the dampers preload and maximum force. Focus then turned to the structural design phase. 3D CAD was used to generate a digital mock-up of the device and structural analyses were conducted using the finite element method. The proposed device presents an original conceptual layout, characterised by a compact and easy allocation of the piezo-actuator which is installed inside the piston of the damper. A highly efficient transmission chain allows for the transfer of the compression force generated by the piezo-actuator, to four pads of friction material,preventing the motion of the piston along its chamber. Theoretical performances were validated by means of experimental tests carried out on a physical prototype, loaded through a hydraulic test machine.