Structural Health Monitoring: From macro to micro, a progressively detailed assessment of structural performance and damage assessment for immediate response to lifetime analysis.

Abstract

This article investigates structural health monitoring (SHM) of multi-degree of freedom (MDOF) structures after major seismic or environmental events. A recently developed hysteresis loop analysis (HLA) SHM technique has performed robustly for single degree
of freedom (SDOF) and single mode dominant MDOF structures. However, strong ground motions can trigger higher vibration modes, resulting in irregular hysteresis loops and making this otherwise robust identification difficult. This study presents a new filtering tool, enabling reconstruction of single mode dominant restoring force displacement loops which can be readily used for HLA. The proposed filtering tool is based on a classic modal decomposition using optimized mode shape coefficients. The optimization process is carried out in a modal space and is based on decoupling frequency response spectra of interfering modes. Application of modal decomposition using the optimized mode shape coefficients allows for reconstruction of single-mode dominant hysteresis loops, which can be effectively identified using HLA. The proposed filtering tool is validated on the reconstruction of hysteresis loops on an experimental bridge pier test structure with notable contributions from at least two modes. The results show the method eliminates the influence of all higher modes that contain significant energy content and yields the reconstruction of “smooth” single mode dominant hysteresis loops. The resulting SHM analysis on the reconstructed experimental hysteresis loops identified degradation in the elastic stiffness profiles, indicating damage within the structure and matching prior published results based on physical inspection of damage. The overall method presented increases the breadth of potential application of the HLA method and can be readily generalized to a range of MDOF structures.

Journal articles

Poskus, E, Rodgers, GW, Zhou, C and Chase, JG (2018). “Damage Identification for Hysteretic Structures Using a Mode Decomposition Method,” Computer Aided Civil Infrastructure Engineering (CACIE), Vol 33(2), pp. 97-109, ISSN: 1467-8667, doi: 10.1111/mice.12317

Conference articles:

1. Poskus, E, Rodgers, GW and Chase, JG (2017). “Damage Identification for Multi-Degree-of-Freedom Non-linear Hysteretic structures Using an Adaptive Mode Decomposition Technique,” New Zealand Society of Earthquake Engineering Annual Conference (NZSEE 2017) and the Anti-Seismic Systems International Society (ASSISI) 15th World Conference on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures, Wellington, NZ, April 27-29
2. Poskus, E, Rodgers, GW and Chase, JG (2016). “Validation of Damage Identification for Multi-Degree-of-Freedom Non-Linear Hysteretic Structures Using a Novel Mode Filtering Method,” New Zealand Society for Earthquake Engineering Annual Technical Conference (NZSEE 2016), Christchurch, NZ, April 1-3
3. Poskus, E, Zhou, C, Rodgers, GW and Chase, JG (2015). “Damage Identification of Hysteretic Test Structures,” NZ Society of Earthquake Engineering Annual Conference (NZSEE 2015), Rotorua, NZ, April 10-12