Damage Detection of Offshore Platforms Using Dispersion Analysis in HHT Frequency Spectrum

A new damage assessment method is proposed for aging offshore platforms based on dynamic tests. The stiff nesses of the measured model corresponding to the two measurement moments are estimated by a series of stiffness-correction factors, respectively. Based on these stiffness-correction factors a new damage indicator is defined aiming at reducing influences of existed damages accumulated before the first measurement on damage assessment occurred between the two adjacent measurements. One theoretical improvement is that the requirement using the stiffness matrix of FEM to replace the one of the measured model can be ignored in the calculation of MSE of the measured model. The other development is influences of damages accumulated before the first measurement on damage detection occurs between the two measurements could be reduced greatly, which is very important for aging platforms because these platforms have not been tested aiming at damage detection during their previous service life, especially for most platforms in China. A jacket platform is chosen for numerical studies, and numerical results show that the proposed method could identify damages occurred between the two measurements properly, even including damage severity estimation.

Download Full-text

Damage Detection for Offshore Platforms Based on Modal Redundancy Index of Damaged Member

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.663.109 ◽

2013 ◽

Vol 663 ◽

pp. 109-115

Author(s):

Wei Zhang ◽

Xiang Shi ◽

Xiao Long Xu

Keyword(s):

Numerical Simulation ◽

Damage Detection ◽

Strain Energy ◽

Engineering Application ◽

Offshore Platforms ◽

Different Types ◽

Reference Index ◽

The Relationship ◽

Redundancy Index ◽

Strain Energy Method

According to the phenomenon that global damage detection of jacket platform is influenced by structure redundancy of damaged member, the concept of modal redundancy index (MRI) of damaged member is proposed. Through numerical simulation by means of mode strain energy method, the way that MRI of damaged members in different types and positions changed was studied, as well as the relationship between MRI and global damage detection. The numerical simulation result demonstrated that when MRI of pile element is less than 2.1×103, damage can be detected; when MRI of slanted brace element is less than 1.5×105, damage can be detected; when MRI of horizontal brace element is more than 5.8×105, damage cannot be detected. Therefore MRI can be a reference index in engineering application of global damage detection of offshore platforms.

Download Full-text

Damage Detection in Offshore Platforms Using Vibration Information

Journal of Energy Resources Technology ◽

10.1115/1.3231263 ◽

1986 ◽

Vol 108 (2) ◽

pp. 97-106 ◽

Cited By ~ 6

Author(s):

F. Shahrivar ◽

J. G. Bouwkamp

Keyword(s):

Damage Detection ◽

Oil And Gas ◽

Gas Production ◽

Offshore Platforms ◽

Oil And Gas Production ◽

Mass Eccentricity ◽

Detection Capabilities ◽

Offshore Oil And Gas ◽

Offshore Oil ◽

Mass Increase

Damage detection based on changes in dynamic characteristics is considered for eight-legged k-braced steel offshore oil and gas production towers. Both experimental and analytical results are presented to improve damage detection capabilities. A 1/50th scale plastic model representing the structural system of a typical full-scale tower in 218 ft (66m) of water is used for the studies. Effects of severance of diagonal bracing members on selected vibration frequencies and mode shape parameters measurable at the deck are investigated. The effects of changes in deck mass, increase in jacket mass, and deck mass eccentricity on the selected parameters are also investigated and are shown to be different from the effects of damage.

Download Full-text

Deep learning methods for damage detection of jacket-type offshore platforms

Process Safety and Environmental Protection ◽

10.1016/j.psep.2021.08.031 ◽

2021 ◽

Vol 154 ◽

pp. 249-261

Author(s):

Xingxian Bao ◽

Tongxuan Fan ◽

Chen Shi ◽

Guanlan Yang

Keyword(s):

Deep Learning ◽

Damage Detection ◽

Offshore Platforms ◽

Learning Methods

Download Full-text

ON THE RESULTS OF STUDYING THE INFLUENCY OF VIBRATION-FLUCTUATIONS PROCESSES ON THE RESOURCE OF WELDED JOINTS OF MARINE STATIONARY PLATFORMS FOR OIL, GAS AND OTHER USEFUL MINERALS ON THE SHELF

Akustika ◽

10.36336/akustika201934148 ◽

2019 ◽

Vol 34 ◽

pp. 148-151

Author(s):

Ivan Starokon

Keyword(s):

Fluid Flow ◽

Frequency Spectrum ◽

Welded Joints ◽

Natural Frequencies ◽

Practical Importance ◽

Offshore Platforms ◽

Hydrodynamic Load ◽

Great Practical Importance ◽

Oil Gas

The study of the occurrence of resonant oscillations when the frequency spectrum from the hydrodynamic load coincides with the natural frequencies of the elements of the offshore platforms, as a result of which the acting stresses multiply, has a great practical importance. In the process of research it was found that the most loaded elements of the platform under such an impact are the supports. In this research, the degree of influence on the supports of the force arising due to the formation and breakdown of vortices during the flow around the supports with a fluid flow is estimated. A conclusion about the influence of vibrational-fluctuations processes on the resource of offshore stationary platforms is based on this research.

Download Full-text

Damage detection in jacket type offshore platforms using modal strain energy

STRUCTURAL ENGINEERING AND MECHANICS ◽

10.12989/sem.2009.33.3.325 ◽

2009 ◽

Vol 33 (3) ◽

pp. 325-337 ◽

Cited By ~ 10

Author(s):

B. Asgarian ◽

M. Amiri ◽

A. Ghafooripour

Keyword(s):

Damage Detection ◽

Strain Energy ◽

Offshore Platforms ◽

Modal Strain Energy

Download Full-text

Error Processing Techniques of Integral Velocity Based on Frequency Spectrum Forecasting

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.511-512.370 ◽

2014 ◽

Vol 511-512 ◽

pp. 370-374

Author(s):

Ai Guo Chen ◽

Cheng Yong Wang ◽

Jia Wei Ye

Keyword(s):

Frequency Spectrum ◽

Measurement Technique ◽

Time Measurement ◽

Error Processing ◽

Offshore Platforms ◽

Ship Wave ◽

Velocity Error ◽

Processing Techniques

The integral velocity error at the head end and the tail end of wave movement of ships or offshore platforms are too great. By improving the forecasting technique based on frequency spectrum, the integral velocity errors are maximally corrected and the wave movement of ships or offshore platforms is successful forecasted longer time ahead of time. Measurement technique of ship wave movement based on accelerometers array will be practically used.

Download Full-text