Method for identifying modal parameters of ocean platform structure

Abstract

The invention discloses a method for identifying modal parameters of an ocean platform structure. The method comprises the following steps of 1, carrying out directional processing on input environmental excitation response data of the ocean platform structure; 2, constructing a Hankel matrix by utilizing the structural environment excitation response data, carrying out orthogonal triangular decomposition on the Hankel matrix to obtain a projection matrix, then carrying out singular value decomposition on the projection matrix, and solving a vibration system state space equation by utilizing aleast square method and the like; and finally, extracting structural modal information from the system matrix A and the output matrix C in the state-space equation of the vibration system; 3, performing clustering analysis based on density division on the modal result set by utilizing a density-based clustering algorithm; and 4, obtaining real modal parameters, and analyzing a result of the realmodal parameters. According to the method, the real mode of the ocean platform structure can be automatically extracted from the environmental response signal. Therefore, most of noise points are eliminated. Moreover, the health condition of the platform can be evaluated according to a modal parameter identification result.

Description

technical field [0001] The invention relates to an ocean platform, in particular to a method for identifying structural modal parameters of an ocean platform. It belongs to the field of offshore oil engineering. Background technique [0002] The modal parameter identification of offshore platform structure under environmental excitation is of great significance to the design and safety of platform structure. How to exclude the influence of false modes from the modal result set and maximize the selection of real modes has become a difficult point in the engineering application of this technology. [0003] At present, for the identification of modal parameters, the main method is to use the data-driven random subspace algorithm, and the identified modal result set includes real modal components and false modal components. Generally, the stability diagram method is used to judge the true and false modes in the modal result set. The stability map method works well when dealin...

AI Technical Summary

Problems solved by technology

[0004] The main purpose of the present invention is to overcome the above-mentioned shortcomings existing in the prior art, and provide an improved identification method of the modal parameters of the offshore platform structure, which can automatically extract the real mode of the offshore platform structure from the environmental response signal, It not only eliminates most of the noise points, solves the problem of subjective errors that may be caused by manual screening, and greatly improves the efficiency and accuracy of modal post-processing; moreover, it can also improve the health of the platform based on the modal parameter identification results. condition was assessed, contributing to a more detailed understanding of the health of offshore platform structures

Images