Damage Localization of Structures Base on Deterministic-Stochastic Models
|關鍵字:||結構健康監測;系統識別;確定-預測系統;破壞定位向量;科技廠房;structural health monitoring;system identification;deterministic-stochastic systems;damage locating vectors;high-tech industrial fabs|
This study aims at developing a structural health monitoring technique for high-tech industrial fabs, meant to reduce the seismic risk for domestic industries. In this dissertation, a scheme integrated with deterministic–stochastic subspace system identification and the method of damage localization vector (DLV) is proposed for damage detection of structures based on seismic response data. The algorithms considered for system identification are primarily the Numerical algorithms for Subspace State Space System Identification (N4SID) and the Multivariable Output-Error State sPace (MOESP). Via a series of numerical simulations and shaking table tests, it has been shown that local damages (stories) can be identified from the global responses of earthquakes. For the tests conducted in NCTU large-scale structural laboratory, structural damage is simulated by removing part of the diagonal braces, while for those conducted in NCREE, it is simulated by reducing the cross-sectional area of the columns at the bottom ends. Both series of shaking table tests consider single and multiple damage conditions at various locations. The wireless transmission system (NTU-WSU) developed by NTU was adopted to monitor the dynamic responses in the NCTU tests. Both full and partial observation conditions have been considered in the system identification. In addition to the structural damage detection based on comparion with the intact structure, comparsion with the as-damaged (ill - conditioned) structure has also been considered to further identify new or extended damages. It has been shown that the results by using N4SID are consistently better in almost all cases, regardless of numerical simulations or shaking table tests. The advantage of using N4SID is even more pronounced as dealing with more complex conditions such as multi-damage and/or partial observation. The damage localization of fab structures is investigated using a typical triple fab as the object. The N4SID is adopted for system identification under partial observation. Stiffness loss of about 1% in the damaged storey located at either a corner or a side of the structural plane has been considered. Simulation results indicate that the proposed scheme can successfully identify the damaged storey. The performance in terms of damage index is more sensitive as the structure is damaged at the corner. This preliminary study suggests the potential of the proposed scheme for practical use on structural health monitoring of industrial fab structures. It deserves further research.