Damage identification in offshore jacket structures based on modal flexibility

A modal flexibility-based method using finite element model updating technique for damage detection purposes is presented. The motivation for choosing modal flexibility is explained and the objective function for an iterative optimization process is formulated. The simulated platform FE model is established with single and triple damage cases where noise contamination and model uncertainty are considered. Monte Carlo simulation is used for random parameter study. A substructure optimization algorithm is proposed together with a threshold to lower the number of design variables. When the flexibility-based method employs only the first order modal parameter and translational degree of freedoms on merely 4 nodes, satisfactory results can still be derived under high level of contaminated noise and random errors on elemental elasticity modulus and mass density. The influence of random parameters, spatial-incompleteness and tiny damage cases are discussed with several important conclusions summarized. The proposed substructure optimization algorithm and crucial problems during optimization process are described. The algorithm is applied to two numerical examples including a simply-supported beam and a jacket-platform, the study based on equivalent model reveals better accuracy and efficiency of the proposed algorithm, even with 3% measurement noise and model uncertainty.

Language

  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01685746
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 26 2018 3:03PM