Identification of Natural Frequencies and Damping Ratios of Brick-Concrete Structural Buildings Under Blasting Vibration Excitation

The identification of natural frequencies and damping ratios in brick-concrete structures subjected to blasting vibrations is a critical prerequisite for stability analysis. However, results from a single modal identification method exhibit considerable errors and do not address uncertainty. This study proposes a multi-domain collaborative and clustering fusion (MDCCF) approach, validated through numerical simulations. Building on this foundation, we conducted vibration monitoring and candidate frequency/damping ratio identification for brick-concrete structures under deep-hole blasting in open-pit mines, followed by probabilistic distribution analysis of the identified parameters. Results demonstrate that the MDCCF method achieves higher accuracy than covariance-driven stochastic subspace identification (SSI-cov)-K-means and peak-picking (PP)-K-means methods, with candidate natural frequencies and damping ratios more closely approximating theoretical values. The ten candidate natural frequencies of the structure under deep-hole blasting were identified as 7.69 Hz, 10.559 Hz, 17.2068 Hz, 22.095 Hz, 27.099 Hz, 29.7741 Hz, 34.668 Hz, 40.039 Hz, 48.7882 Hz and 50.6476 Hz, with corresponding candidate damping ratios of 4.4602%, 3.705%, 2.8618%, 2.4161%, 1.9%, 1.45%, 1.11%, 0.8579%, 0.59% and 0.3493%. The natural frequencies and damping ratios of brick-concrete structures exhibit strong normal and Gamma distribution characteristics, respectively. Bootstrap analysis was further employed to quantify the statistical uncertainty of the identified natural frequencies and damping ratios, and the corresponding 95% confidence intervals were obtained. The identified frequency groups are interpreted as candidate modal frequencies rather than definitively confirmed global structural modes.