Nakorn Suttara creator Chiu, Gregory L.F. Chairperson Widjaja, Joko Harsono Co-Chairperson Pennung Warnitchai Examination Committee Boswell, Laurie Examination committee Royal Thai Government Fellowship Scholarship donor Asian Institute of Technology Fellowship Scholarship donor text series technical report th Pathum Thani, Thailand Asian Institute of Technology 2009 continuing eng 70 leaves : ill. In general, fixed offshore structure is always attacked by dynamic wave loads throughout its service life, but dynamic analysis is often avoided. Commonly, quasi»static is very popular for a long time in design process due to substantial convenience. In turn, if the nonlinearity of soil stiffness under seabed is taken into account, it is known that soil layers are not perfectly stiff unlike idealized fixed support. The characteristic of soil stiffness may affect the global structural stiffness. The monopod and four-leg jacket platforms would be investigated by using computer modeling program, SACS, and MATLAB for analysis. Therefore, structural frequency will become non-constant, and the frequency ratio of wave forces frequency to structural frequency may be close to unity leading to so-called resonance situation. In this study, the non-linear dynamic wave response analysis of fixed offshore structure. In conclusion, the behavior of such structure can be definitely concluded that non-linear soil stiffness significantly affects not only total structural response but also structural periods. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Offshore Technology and Management, School of Engineering and Technology Thesis (M.Eng.) - Asian Institute of Technology, 2009 Offshore structures Dynamics Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B03590 http://203.159.5.9/ait-thesis/detail.php?q=B03590 090907 20260818094307.0