Damage Assessment of Hyperbolic Paraboloidal Shells Using Finite Element Updating

Abstract eng:
Assessment of the structural and functional integrity of civil engineering structures is an essential design issue and of continuous concern during the process of maintenance, repair and upgrading of such structures. The concept of Structural Health Monitoring (SHM) offers means to predict the structural behavior of a particular structure under operating conditions that differ from those taken into consideration in the initial design cycle. Employment of the aforementioned concept requires computational models that are verified, refined and adjusted with respect to actual measurements. In this paper, a finite element updating methodology is presented, which aims to reduce the discrepancies between the dynamic model parameters of the structure and the measurements. A sucessful finite element updating approach must rely on physically meaningful criteria for selecting the updating parameters and the most suitable method in order to modify the mass and stiffness matrices of the computational model. The proposed iterative method is based on a generalized variational principle, a modified version of the Hu-Washizu principle of elastodynamics, which treats displacements, rotations, strains and stresses as independent variables that can be treated as updating parameters. Thus, a more efficient and direct implementation of measurements is possible. Furthermore, the discretization yields simple and effective finite elements especially suited to repetitious computations required in dynamic finite element updating. Different parameter sensitivities are studied. Single and multi-objective optimization processes are carried out using objective functions that include the eigenfrequencies and the strain modal energy of the structure. Finally, some alternative damage scenarios are presented in order to validate the proposed formulation for the case of hyperbolic paraboloidal shell structures. 1

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