近海结构—流体—地基体系的辐射水动力特性和地震分析

本文提出了求解弹性地基上弹性铅直圆柱体与周周液体耦联振动的解析方法。在该方法中采用了改进的数学模型,不仅考虑了结构-流体相互作用,同时还考虑了弹性地基对整个结构-流体-地基体系的影响。文中给出了依赖于激振频率的辐射附加质量和水动力辐射阻尼的解析表达式,分析了它们随激振频率的变化特性,并将之分别与广义质量和广义阻尼作了比较分析。本文还就结构-流体-地基相互作用对于辐射水动力荷载的影响作了描述和研讨。

Hydrodynamic Characteristics and Seismic Analysis of Offshore Cylindrical Structure-Fluid-Soil Systems

An analytical method is developed to solve the coupled vibration problem of an elastic vertical circular cylindrical structure founded on homogeneous elastic soil with surrounding fluid. An improved mathematical model is adopted so that not only the structure-fluid interaction but also the influence of the elasticity of soil are considered.The forced structural vibration problem and the fluid radiation problem is uncoupled by means of the orthonomality of the eigen functions and the generalized coordinates associated with the mode shapes of the structure. Two modified orthogonality conditions of vibration mode shapes and expressions of modified generalized mass, stiffness and damping, which satisfy a cantilever beam-type structure with supporting spring, damper and lumped mass, are formulated.The frequency-dependent radiation added mass and hydrodynamic radiation damping are expressed in closed form, and are compared with the generalized mass and damping respectively. Their variations with the exciting frequency are studied as well. A discussion of the influences of structure-fluid interaction and structure-soil interaction upon the hydrodynamic loading is also given.