Fatigue life assessment for offshore structures in the sea of Vietnam | |
| Author | Do Kien Quoc |
| Call Number | AIT Thesis no.ST-86-06 |
| Subject(s) | Offshore structures Materials--Fatigue |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ST-86-06 |
| Abstract | The fatigue life of a typical fixed steel offshore platform installed in the Sea of Vietnam is investigated. For stress and eigenfrequency analysis, the platform is modelled as a three- dimensional frame with a rigid deck at the top. For the random vibration analysis, however, the concept of generalized coordinates is used assuming that it vibrates predominantly with its first mode. Consequently, the structure can be modelled as a generalized single-degree-of-freedom oscillator. The loads due to wave, current and wind action are considered with water wave being the predominant one. Wave action is assumed as a stationary narrow band random process with Gaussian distribution, and the corresponding wave force spectra are determined based on Airy's linear theory. The fatigue life is investigated for various parameters such as current velocity, wind load as percentage of wave load, stress concentration factor, damping ratio, cut-off stress level, etc. The fatigue life according to three models (Miner's model, modified Miner's model, and Shanley's model) is computed and compared. In addition, a new approach for fatigue life prediction is proposed, which is a combination of cumulative damage and first passage. It gives shorter fatigue life predictions than Miner's model. |
| Year | 1986 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ST-86-06 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Wireland, Martin |
| Examination Committee(s) | Przybylo, Waclaw, D. Sc. ;Worsak Kanok-Nukulchai ;Suphat Vongvisessomjai |
| Scholarship Donor(s) | Asian Institute of Technology Partial ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1986 |