Modal Parameter Identification for Building Structures under Natural Excitation

Modal parameter identification for building structures under natural excitation represents a widely adopted approach in structural dynamics. The process begins with implementing the Natural Excitation Technique (NExT) to extract free vibration responses from ambient vibration data - typically achieved through cross-correlation analysis between response measurements, which mathematically approximates free decay responses. This technique enables comprehensive understanding of structural vibration characteristics under various operational conditions. Subsequently, the AutoRegressive Moving Average (ARMA) method is applied for modal parameter identification, where the AR component models the system's inherent dynamics while the MA component accounts for measurement noise. Implemented through algorithms like least-squares estimation or maximum likelihood methods, this approach effectively identifies critical parameters including natural frequencies, damping ratios, and mode shapes. By integrating these two methodologies with proper signal processing techniques (such as data segmentation and model order selection), we achieve thorough vibration behavior analysis and structural performance evaluation for building systems.