System Identification and Vibration-Based Damage Detection in a Concrete Shear Wall System

Structural Health Monitoring (SHM) based on the vibration of structures has been very attractive subject for researchers in different fields such as: civil, aeronautical and mechanical engineering. System Identification (SI) and Vibration based Damage Identification (VBDI) are two main parts of SHM. A full-scale seven-story reinforced concrete (RC) wall building tested in October 2005 and January 2006 at the University of California at San Diego (UCSD) has been considered here as a case study. The building was excited through four historical California ground motions. The RC wall experienced different levels of damage, progressively under increasing intensity of ground motions. At different levels of damage, the building was subjected to ambient vibration tests and low-amplitude White Gaussian Noise (WGN) base excitation. In this study, the response of the structure to ambient vibration tests was used to identify damage using VBDD methods. The frequency domain decomposition method (FDD) is used here to identify the modal parameters of the building. Damage changes the modal properties (frequency, mode shape and damping) by reducing the stiffness. Therefore, changes in the vibration characteristics of the structure can be used to identify location and severity of damage. A mode shape curvature-based method is used to detect and localize damage. Also a data-driven technique based on Neural Networks has been developed to identify the damage in the structure. The results show a close correlation with the structural damage observed in the experimental study.