A simplified nondeterministic analysis of offshore towers subjected to earthquakes | |
| Author | Mana Mahasuverachai |
| Call Number | AIT Thesis no. 1330 |
| Subject(s) | Structural dynamics Oil well drilling, Submarine |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand |
| Publisher | Asian Institute of Technology |
| Abstract | A stochastic method of analysis of offshore towers subjected to earthquakes is investigated. The equations of motion include the expression for fluid reaction proposed by Morison, and the input horizontal ground acceleration is in the form of a power spectral density function suggested by Kanai and Tajimi. The nonlinearities due to drag effects are linearized by using a statistical linearization approach. Modal analysis is used to solve the response statistics and then the response itself by two methods of approximation: (1) Coupled damping is replaced by another diagonalized matrix which causes the same amount of energy dissipation. (2) By neglecting off diagonal terms in the coupled damping matrix and also dropping cross terms in the power spectral density function for the response. Four typical deep water towers are analyzed as lumped mass models, each with seven degrees of freedom. Particular emphasis is placed on maximum displacements total transverse shears and total overturning moments. The analysis by the second approximate method using the first three normal modes is found to be very accurate and the computing time involved is approximately only twenty-five percent of that needed by the first approximate method. |
| Year | 1978 |
| Type | Thesis |
| School | Student Research Before 1979 |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Thesis (Year <=1979) |
| Chairperson(s) | Karasudhi, Pisidhi |
| Examination Committee(s) | Tanabe, Tada-Aki ;Usami, Tsutomu |
| Scholarship Donor(s) | Government of the Federal Republic of Germany |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1978 |