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Structural Engineering and Mechanics Volume 59, Number 1, July10 2016 , pages 187-207 DOI: https://doi.org/10.12989/sem.2016.59.1.187 |
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Operational modal analysis of structures by stochastic subspace identification with a delay index |
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Dan Li, Wei-Xin Ren, Yi-Ding Hu and Dong Yang
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| Abstract | ||
| Practical ambient excitations of engineering structures usually do not comply with the stationary-white-noise assumption in traditional operational modal analysis methods due to heavy traffic, wind guests, and other disturbances. In order to eliminate spurious modes induced by non-white noise inputs, the improved stochastic subspace identification based on a delay index is proposed in this paper for a representative kind of stationary non-white noise ambient excitations, which have nonzero autocorrelation values near the vertical axis. It relaxes the stationary-white-noise assumption of inputs by avoiding corresponding unqualified elements in the Hankel matrix. Details of the improved stochastic subspace identification algorithms and determination of the delay index are discussed. Numerical simulations on a four-story frame and laboratory vibration experiments on a simply supported beam have demonstrated the accuracy and reliability of the proposed method in eliminating spurious modes under non-white noise ambient excitations. | ||
| Key Words | ||
| operational modal analysis; non-white noise ambient excitations; stochastic subspace identification; delay index | ||
| Address | ||
| Dan Li: School of Civil Engineering, Hefei University of Technology, Hefei, 230009, China; Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore Wei-Xin Ren: School of Civil Engineering, Hefei University of Technology, Hefei, 230009, China Yi-Ding Hu: School of Information Engineering, Wuyi University, Jiangmen, 529020, China Dong Yang: School of Civil Engineering, Hefei University of Technology, Hefei, 230009, China | ||