RESPONSES OF A SOFT-SETTLED-TYPE OFFSHORE STRUCTURE
SUBJECTED TO SEISMIC FORCES
Kiyoshi SHINGU* and Masaaki SAKUTA**
* Department of Oceanic Architecture & Engineering, College of Science & Technology,Department of Computer Science, Graduate School of Science & Technology,Nihon University, Funabashi, Chiba
** Department of Oceanic Architecture & Engineering, College of Science & Technology,Nihon University, Funabashi, Chiba
A soft-settled-type offshore structure is one of the offshore structures, and the concept of this structure was proposed by one of the authors of this paper. The structure exerts lesser weight on the seabed. This allows it to resist wave forces while being able to slide against seismic forces, with magnitude greater than the one in a certain level. The structure does this by adjusting the friction forces between the structure and the ground.
In this paper, dynamic response analyses of the moored-type of the soft-settled-type offshore structure with a circular cross section subjected to seismic forces in the horizontal direction are presented. Furthermore, experiments on a model of such a structure are presented, and the characteristics of the structure are clarified.
1. INTRODUCTION
The soft-settled-type offshore structure is an offshore structure proposed by Sakuta, et al1) . The structure in question is so designed as to be free from seismicity by allowing some degree of gliding to bemade between the ground and the structure bottom when dynamic external forces including seismic forces are applied with the adjustment of the buoyancy and the weight of structure. Later, theoretical and experimental researches have been conducted by Shingu, Sakuta et al.2)〜5). These researches are concerned mainly with independent or moored-type structures having rectangular cross section. A series of these researches is summarized in Reference 6). In the paper, water reservoir experiments are conducted with independent and moored-type of soft-settled-type offshore structures having a rectangular cross section and comparison of the experimental values with theoretical ones are made.
The authors7),8) of this paper have performed research concerning the moored-type of soft-settled-type offshore structures having a circular cross section. This paper is a revised version of the variety of the study
