Structural identification with incomplete instrumentation and global identifiability requirements under base excitation

Estimating the mass and stiffness parameters of a structural system via its vibration response measurements is the primary objective in the field of modal testing and structural health monitoring. The attainment of this objective, however, is hindered by various practical and theoretical issues. One such issue is incomplete instrumentation, leading to spatially incomplete mode shapes and often nonunique identification results. When the excitation is induced by ground motion, the problem is further complicated because of arbitrary normalization of mode shapes. This study attempts to address these issues for shear-building type structures. Mode shape normalization and expansion approaches are developed that utilize the topology of the structural matrices. Theoretical constraints regarding minimal instrumentation and the necessity for any a priori information are addressed vis-a-vis the requirements for global identifiability. Some practical implementation issues are discussed. The performance of the method is evaluated using numerical simulations and shake table experiments. Copyright (c) 2015 John Wiley & Sons, Ltd.