波流联合作用下弹性支承梁动力特性分析

为分析铰接塔平台的动力特性,建立了部分水下带有集中质量块的等截面弹性支承梁运动模型。用耦合弹簧刚度矩阵模拟铰接头处桩基础与土层之间的相互作用,考虑波浪和海流对梁的Morison力作用及由集中质量块引起的轴向力作用,建立了弹性支承等截面梁横向强迫振动的运动控制模型。采用Runge-Kutta数值方法分别研究了耦合弹性支承和独立弹性支承条件下梁的动力响应。研究表明,波流联合作用下,弹性支承等截面梁的有阻尼固有频率并未发生变化,系统同样将发生超谐共振;海流对不同弹性支承结构的主共振响应影响是不同的。可为海洋工程中铰接塔平台的动力特性分析提供参考。

Dynamic characteristic analysis of elastically supported immersed beam under combined wave current loads

To investigate the dynamic characteristic of the articulated tower platform (ATP), an dynamic response analytical model of an elastically supported immersed uniform beam carrying an eccentric tip mass is studied. Taking into account the axial force due to the tip mass and the wave force based on Morison formula, the mathematic model for transversal forced vibration of a cantilever beam under the waves current excitation was presented, in which a coupled stiffness matrix at the mudline is to model the interaction between the pile foundation and the surrounded soil. The dynamic behaviors of the structure under different supported conditions were investigated separately by the numerical method of Runge Kutta. It is shown that the damped natural frequencies of the immersed beam don’t change when considering the combined wave current excitation, that the supper harmonic resonances of the system occur all the same, and that the influences of the current load on the main resonances of the elastically coupled and independent supported structures are different. The correlative conclusions supply references for the dynamic behaviors analysis of the ATP in the ocean engineering.