Abstract
Offshore structures in zones of active seismicity are under a potential threat caused by the combined action of earthquakes and waves. Taking a submerged circular cylinder as the prototype and considering water-structure-soil interaction, the present study is devoted to the investigation of the combined action of earthquakes and waves. Water-cylinder interaction and soil-structure interaction are simulated by added mass and rigid circular massless foundations, respectively. Based on the radiation and diffraction wave theory, the scaled boundary finite element method is utilized to determine the earthquake-induced and wave-induced pressure on a circular cylinder. Then, a closed-form expression for the natural frequencies and mode shapes of the system is derived by using the transfer matrix method, where the transfer matrix is obtained based on Euler–Bernoulli’s beam differential equation. Furthermore, the dynamic response of the system under the combined action of earthquakes and waves is derived by using the mode superposition method. Finally, the effects of the hydrodynamic force, wave force, and soil-structure interaction on the dynamic response of the submerged cylinder are investigated. The results indicate that the wave forces can substantially increase the dynamic responses of the cylinder and that the influence increases as the stiffness ratio increases and the width-depth ratio decreases. It is necessary to consider the combined action of earthquakes and waves in the seismic design of offshore structures.
Highlights
An increasing number of offshore structures, such as seacrossing bridges, artificial islands, and offshore wind turbines, have been constructed around the world in recent years especially in China
Is means that an earthquake can coincide with a wave condition [1]. erefore, to guarantee the reliability of offshore structures, it is necessary to investigate the dynamic response of offshore structures under the combined action of earthquakes and waves. is paper takes a submerged circular cylinder as the prototype to study the earthquake and wave responses of offshore structures including waterstructure-soil interaction
Earthquake-induced hydrodynamic forces on a circular cylinder have been studied by many researchers [5] who initially investigated the effects of hydrodynamic forces on the earthquake response of cantilever circular cylinders. e results indicated that the water compressibility is negligible for slender cylinders. e surface waves have no influence on earthquake-induced hydrodynamic forces except at low loading frequencies and will have little consequence on the seismic response of cylinders surrounded by water. e seismic responses of circular cylinders were further investigated by Williams [6] and Advances in Civil Engineering
Summary
Earthquake and Wave Analysis of Circular Cylinder considering Water-Structure-Soil Interaction. Offshore structures in zones of active seismicity are under a potential threat caused by the combined action of earthquakes and waves. Taking a submerged circular cylinder as the prototype and considering water-structure-soil interaction, the present study is devoted to the investigation of the combined action of earthquakes and waves. The dynamic response of the system under the combined action of earthquakes and waves is derived by using the mode superposition method. The effects of the hydrodynamic force, wave force, and soil-structure interaction on the dynamic response of the submerged cylinder are investigated. It is necessary to consider the combined action of earthquakes and waves in the seismic design of offshore structures
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