Structural Monitoring and Maintenance

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Stable modal identification for civil structures based on a stochastic subspace algorithm with appropriate selection of time lag parameter

  • Wu, Wen-Hwa (Department of Construction Engineering, National Yunlin University of Science and Technology) ;
  • Wang, Sheng-Wei (Intelligent Electronic Systems Division, National Chip Implementation Center, National Applied Research Laboratories) ;
  • Chen, Chien-Chou (Department of Construction Engineering, National Yunlin University of Science and Technology) ;
  • Lai, Gwolong (Department of Construction Engineering, National Yunlin University of Science and Technology)
  • Received : 2017.11.02
  • Accepted : 2017.11.24
  • Published : 2017.12.25
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Abstract

Based on the alternative stabilization diagram by varying the time lag parameter in the stochastic subspace identification analysis, this study aims to investigate the measurements from several cases of civil structures for extending the applicability of a recently noticed criterion to ensure stable identification results. Such a criterion demands the time lag parameter to be no less than a critical threshold determined by the ratio of the sampling rate to the fundamental system frequency and is firstly validated for its applications with single measurements from stay cables, bridge decks, and buildings. As for multiple measurements, it is found that the predicted threshold works well for the cases of stay cables and buildings, but makes an evident overestimation for the case of bridge decks. This discrepancy is further explained by the fact that the deck vibrations are induced by multiple excitations independently coming from the passing traffic. The cable vibration signals covering the sensor locations close to both the deck and pylon ends of a cable-stayed bridge provide convincing evidences to testify this important discovery.

Keywords

Acknowledgement

Supported by : Ministry of Science and Technology of Republic of China

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Cited by

  1. Modal parameter identification for closely spaced modes of civil structures based on an upgraded stochastic subspace methodology vol.15, pp.3, 2019, https://doi.org/10.1080/15732479.2018.1547770
  2. Investigation of modal damping ratios for stay cables based on stochastic subspace identification with ambient vibration measurements vol.22, pp.16, 2017, https://doi.org/10.1177/1369433219855900