Automatic modal parameter identification of high arch dams: feasibility verification
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EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION
Earthq Eng & Eng Vib (2020) 19: 953-965
October, 2020
DOI: https://doi.org/10.1007/s11803-020-0606-6
Automatic modal parameter identification of high arch dams: feasibility verification Li Shuai†, Pan Jianwen‡, Luo Guangheng† and Wang Jinting§ Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China
Abstract:
Modal parameters, including fundamental frequencies, damping ratios, and mode shapes, could be used to evaluate the health condition of structures. Automatic modal parameter identification, which plays an essential role in realtime structural health monitoring, has become a popular topic in recent years. In this study, an automatic modal parameter identification procedure for high arch dams is proposed. The proposed procedure is implemented by combining the densitybased spatial clustering of applications with noise (DBSCAN) algorithm and the stochastic subspace identification (SSI). The 210-m-high Dagangshan Dam is investigated as an example to verify the feasibility of the procedure. The results show that the DBSCAN algorithm is robust enough to interpret the stabilization diagram from SSI and may avoid outline modes. This leads to the proposed procedure obtaining a better performance than the partitioned clustering and hierarchical clustering algorithms. In addition, the errors of the identified frequencies of the arch dam are within 4%, and the identified mode shapes are in agreement with those obtained from the finite element model, which implies that the proposed procedure is accurate enough to use in modal parameter identification. The procedure is feasible for online modal parameter identification and modal tracking of arch dams.
Keywords:
automatic modal parameter identification; high arch dam; DBSCAN algorithm; stochastic subspace identification; stabilization diagram; ambient vibration
1 Introduction A number of high arch dams are located in southwestern China, such as the Jinping I Dam (305 m high), Xiaowan Dam (294.5 m high), Xiluodu Dam (285.5 m high), and Dagangshan Dam (210 m high). The health status of these dams during their lifetime has been receiving greater attention in recent years. Structural health monitoring (SHM) (Tang et al., 2019; Hsu et al., 2019) is an effective method for evaluation of the health status of structures and has been the subject of significant research in recent years (Van der Auweraer and Peeters, 2003). Various prior studies (Cheng and Zheng, 2014; Weng and Loh, 2010) indicate that modal parameters can be used to evaluate the health/condition of arch dams, including fundamental frequencies, damping ratios, and mode shapes. Therefore, modal parameter identification, which extracts structural dynamic parameters from response signals, is the core of SHM (Magalhães and Cunha, 2011). Correspondence to: Wang Jinting, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China Tel: +86-10-6278 3165; Fax: +86-10-6278 2159 E-mail: [email protected] † PhD; ‡Assistant Prof
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