Hybrid identification method for multi-story buildings with unknown ground motion: Experimental investigation

A hybrid method for identifying both structural parameters and ground motion of an earthquake-excited multi-story building is experimentally examined in this paper. A series of shaking table tests was conducted on a building model under different kinds of ground motion. Absolute acceleration responses at all floors of the test building were measured and integrated to obtain velocity and displacement responses. All the measured and integrated responses are then analysed using the hybrid identification method with a shift-average procedure to identify the stiffness and damping parameters as well as to reconstruct the unknown seismic input. To evaluate the reliability of the method, the identified structural stiffness is compared with the theoretical value computed from given material and geometric properties, and the identified structural damping is compared with that obtained from a frequency domain identification method. The reconstructed seismic excitation is compared with that recorded during the shaking table test in both the frequency domain and time domain. All comparisons show a good agreement, indicating that the hybrid identification method is potentially a promising technique for structural parameter and seismic excitation identification of multi-story buildings using output measurements only.