Sea ice can induce the offshore jacket structure to vibrate in Bohai Sea. Ice-induced vibrations of offshore structure could lead to the associated accidents of pipeline on the platform. Based on the data observed on the platforms of JZ202 in Bohai Sea, the typical history curve of deck acceleration is obtained and used to analyze the excitation of pipelines. A mechanical model of structural vibration of pipeline system is developed. With finite element modeling, the dynamic responses of the main pipeline system and the local structure of pipeline induced by deck vibration are calculated. The results show that the ice-induced vibration and the form of pipeline have major effect on the vibration property of the pipeline system.
Sea ice is the dominant environmental load on offshore structures in Bohai Sea. Design of ice-resistance platforms has usually considered the maximum bearing capacity under the limited ice load. However, the effects of offshore platforms and facilities induced by the dynamic ice load have not been well considered. Based on the data observed on the platforms, sea ice can induce the periodic load and make the offshore jacket structures vibrate with major acceleration (Yue and Bi, 2000). For the jacket platforms for producing natural gas, there are complicated natural gas pipelines. Ice-induced vibrations could not only result in the fatigue failure of jacket but also lead to the associated accidents of pipelines on the platform, such as fatigue fracture of pipe and looseness of flange. So it is necessary to analyze dynamic response by ice-induced vibration for gas pipeline system on the jacket platforms. Normally, the vibrations of a pipeline system can be excited by internal force, such as reciprocating compressors and pumps, two phase flow, water hammer and external forces which can be formed by wind, current or earthquake.
