Damage Detection of Miter Gates Through Nonlinear Model Updating

Miter gates are a critical component of many navigation locks in the inland waterway infrastructure. Due to deterioration and impacts from debris or vessels, gaps can develop between the bearing surfaces supporting the miter gates. This loss of bearing contact creates a redistribution of stress that is typically not accounted for in design, which can lead to accelerated deterioration and possibly unexpected failure of the gate. We present a novel approach to detecting the loss of bearing contact by finite element (FE) model updating. The contact interface is modeled using nonlinear springs with unknown parameters. These parameters are estimated by minimizing the difference between in-situ measured strain and the strain predicted by the FE model. This is naturally formulated as an optimization problem, where the unknown spring parameters are the optimization variables. The ensuing optimization problem is nonconvex, therefore, multiple local searches are performed to increase the chance of finding the global optimum. Two types of springs are considered for modeling the nonlinearity of the boundary conditions, namely, a gap element and a cubic spring. This paper presents both the formulation and validation of the proposed approach.