A two-step mode shape expansion method for offshore jacket structures with physical meaningful modelling errors

作者：Liu Fushun^*; Li Huajun

来源：Ocean Engineering, 2013, 63: 26-34.

DOI：10.1016/j.oceaneng.2013.01.030

• Mode shape expansion
• Three-dimensional
• Frame structures
• Physical meaningful modeling error
• Offshore jacket structure

A two-step mode shape expansion methodology is proposed for offshore jacket structures when modelling errors between the finite element model and the tested structure are taken into account and estimated in a physical meaningful interval. In the first step, initial guess on mode-correction factors is refined by neglecting these modelling errors; then in the second step, these modelling errors are considered by introducing a series of model-correction factors, which are assigned with physical meanings by using constrained linear least squares technique. Therefore, measured mode shapes can be expanded with an improved convergence performance, and the model-correction factors are estimated within a physical meaningful interval. A three-dimensional five-storey frame structure is firstly employed to investigate the performance of the proposed method, and results show that the approach can reliably expand measured mode shapes with improved convergence performance, and the modelling errors can be estimated with physical meaning. Furthermore, the performance of the approach is also studied by a steel three-dimensional platform, and experimental results demonstrate that mode shapes can be expanded properly when a reference constraint on mode-corrections factors is used based on the mode shape values from the FEM model, and can estimate modelling-correction factors in an expected physical meaningful interval.

• 出版日期2013-5-1
• 单位中国海洋大学