ABSTRACT

In order to clarify the effect of earthquake on the behavior of offshore structures in ice-covered waters, analyses and experiments have been performed as a research project of the Japan Ocean Industries Association. Ice-covered waters are classified into four categories of sea ice states, and seismic load upon fixed offshore structures under these categories of ice states is evaluated. Earthquake induces dynamic water pressure, which increases greatly by the ice sheet attached around the offshore structure. The dynamic pressure vanishes, however, by breaking the ice at the wall of the structure. The results are being used for preparation of a guideline for seismic design of offshore structures in icecovered waters.

INTRODUCTION

In some locations, ice covered waters overlap with earthquake zones where ice-resistant and seismic offshore structures are required. It is not seldom that earthquake occurs in wintertime and offshore structures suffer both due to ice and seismic loads. One of the important but uncertain designs conditions for fixed offshore structures constructed in ice-covered waters may be the seismic load. There is no design rule or recommendation for seismic design of offshore structures constructed in ice-covered waters, but only some description, for example in API (1995), CSI (1992), of special consideration on earthquake for the response of iceresistant structures. The Japan Ocean Industries Association has organized a working group lbr investigation of earthquake effect on oflghore structures in ice-covered waters. Conceptual design of offshore oil production platform has been performed to identify research items and themes. Analyses and experiments have been performed to investigate the behavior of the platform under both ice and earthquake conditions. This paper presents the results of the research obtained so far.

RESEARCH PROCESS

1. Conceptual design Conceptual design of oil production platform was performed under predetermined design conditions and functions of the platform.

This content is only available via PDF.
You can access this article if you purchase or spend a download.