System identification (SID) technique is applied to determine structural properties such as the mass, damping, and stiffness from the structure response records of the October 1987 Whittier earthquakes. The objectives are: (1) prediction of the structural response to future earthquakes, (2) to detect the structural damage, and (3) to study the nonlinear system effect. These efforts would help to develop the nonlinear SID techniques suitable for applications in earthquake design.
