液固耦合作用对不同截面深水桥墩的自振特性影响研究

摘要

This paper mainly analyzes the establishment of liquid-solid coupling model of deep-water piers in AN⁃SYS software. Through the additional quality resulting from Morison equation, it explores the hydrodynamic pres⁃sure on three different types of piers with equal cross-sectional areas, which would subject to the same hydrody⁃namic pressure in water of the same depth. Then, it establishes a solid unit and Fluid30 unit by use of ANSYS to analyze effects of liquid-solid coupling on vibration frequency of different piers. Through the case study, it found out that effects of liquid-solid coupling on the pier's vibration frequency was significant and its biggest decrease of the vibration frequency was 24.2% when the pier was completely submerged in water. Further research showed that for the different piers of the same cross-sectional areas in water of the same depth, the vibration frequency de⁃clined differently due to different liquid-solid coupling orthographic projection of the contact surface area along the axis direction. It maintains that the greater the coordinate axis cross-sectional area along the positive direction is, the more the bending vibration frequency and distortional natural frequency along the axis decreases.%介绍了深水桥墩液固耦合模型在ANSYS软件中模型的建立。利用Morison方程提出的附加质量概念考虑动水压力对桥墩作用，采用3种截面积相等的不同类型桥墩，即淹没水深相同时，所受动水压力相等。利用ANSYS建立实体单元与Fluid30单元来分析液固耦合作用对不同类型桥墩的自振特性影响。通过实例分析发现液固耦合对桥墩自振频率的影响是显著的，桥墩完全被水淹没时，其自振频率最大下降了24.2％。进一步研究发现相同截面面积的不同类型的桥墩，在相同水深时，由于其液固耦合接触面沿坐标轴方向上的正投影面积大小不一样，造成桥墩沿该方向上自振频率下降量大不相同。且沿坐标轴方向正截面面积越大，桥墩沿该轴方向上的弯曲自振频率和扭曲自振频率下降越大。