Structural Performance Estimation of Gravity-type Caisson Structure by Vibration-based System Identification

In this study, the structural performance of the gravity-type caisson structure is assessed from vibration-based system identification. To achieve the objective, the following approaches are implemented. Firstly, a structural identification algorithm based on the use of vibration characteristics is outlined. Structural stiffness and damping are selected as two key parameters to be identified for model update. Secondly, experimental vibration analysis of a lab-scaled gravity-type caisson structure is described. Vibration tests on 2-D wave flume are performed for a few scenarios such as water-level changes and foundation damage. Experimental modal parameters are extracted by frequency domain decomposition method. Finally, vibration-based structural integrity is assessed for the tested caisson system. A simplified model is formulated to represent the tested structure with the limited degrees-of-freedom that corresponds to the sensors’ degrees-of-freedom. Structural parameters of the simplified model are identified by tuning the natural frequencies and modal damping factors.