SYSTEM-IDENTIFICATION FOR EVALUATING SOIL-STRUCTURE INTERACTION EFFECTS IN BUILDINGS FROM STRONG-MOTION RECORDINGS

Parametric system identification is used to evaluate seismic soil-stru cture interaction effects in buildings. The input-output strong motion data pairs needed for evaluations of flexible- and fixed-base fundame ntal mode parameters are derived. Recordings of lateral free-field, fo undation, and roof motions, as well as foundation rocking, are found t o be necessary for direct evaluations of modal parameters for both cas es of base fixity. For the common situation of missing free-field or b ase rocking motions, procedures are developed for estimating the modal parameters that cannot be directly evaluated. The accuracy of these e stimation procedures for fundamental mode vibration period and damping is verified for eleven sites with complete instrumentation of the str ucture, foundation, and free-field. (C) 1998 John Wiley & Sons, Ltd.