Abstract:

In order to solve the problem of uncertainty of structural damage identification of offshore jacket platforms under random environmental loads such as wind, wave and current, a structural damage identification method of jacket platform based on the change of stiffness parameters was proposed according to the mapping relationship between structural stiffness and damage. Taking the indoor scale model of a jacket platform as the test object, two damage conditions were set up, including a diagonal bar sawing off 2/3 of the outer diameter and completely sawing off on the third layer-X surface of the structure. Under the premise of knowing the structural modal parameters and lumped mass matrix, the most probable value (MPV) of the stiffness parameters of each substructure of the platform under different damage conditions was quantitatively identified. The corresponding posterior uncertainty was analyzed, and then the location and degree of damage were judged. The results show that the posterior uncertainty of stiffness parameters is small, and the identification results of stability and accuracy are good. The identified structural damage location is consistent with the test setting location, and the damage degree under the two damage conditions is 1%-12% and 20%-31%, respectively.

Key words: stiffness parameter, jacket platform, structural damage, quantitative identification, probability of damage, degree of damage