|
Structural Monitoring and Maintenance Volume 4, Number 4, December 2017 , pages 331-350 DOI: https://doi.org/10.12989/smm.2017.4.4.331 |
||
|
Stable modal identification for civil structures based on a stochastic subspace algorithm with appropriate selection of time lag parameter |
||
Wen-Hwa Wu, Sheng-Wei Wang, Chien-Chou Chen and Gwolong Lai
|
||
| 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. | ||
| Key Words | ||
| alternative stabilization diagram; stochastic subspace identification; civil structure; time lag parameter; multiple excitations | ||
| Address | ||
| Wen-Hwa Wu, Chien-Chou Chen and Gwolong Lai: Department of Construction Engineering, National Yunlin University of Science and Technology,123 University Road, Douliu, Yunlin 640, Taiwan Sheng-Wei Wang: Intelligent Electronic Systems Division, National Chip Implementation Center, National Applied Research Laboratories, Hsinchu City 300, Taiwan | ||
