动水力简化计算方法对圆形桥墩传递函数的影响

刚性柱法、莫里森法和基频近似法是可供工程应用的不可压缩无粘性水体地震动水力的简化计算方法。为研究上述方法的差异性，将基于不可压缩无粘性水体辐射理论推导的考虑结构变形的精确解作为标准，从频域传递函数的角度，对各简化方法进行比较分析。以水中悬臂圆柱墩为例，选取2个尺寸参数并设计了84种不同尺寸的桥墩，输入脉冲激励得到墩顶节点的位移传递函数、墩底节点的剪力和弯矩传递函数，提取各传递函数的前两阶共振峰幅值和共振频率，基于标准解结果求得3种简化方法的误差。通过分析误差的范围及变化趋势，发现刚性柱法所得共振峰幅值更精确，基频近似法所得共振周期更精确，莫里森法误差受参数的影响显著。此外，基频近似法所得共振峰幅值大多偏小，而莫里森法所得幅值和周期大多偏大。

EFFECTS OF SIMPLIFIED METHODS FOR HYDRODYNAMIC FORCE ON TRANSFER FUNCTION OF CIRCULAR PIER

The rigid-structure method,Morison method and a method based on approximation of fundamental frequency are applicable simplified methods for the hydrodynamic force of incompressible non-viscous water.To investigate the differences of the above methods,the responsesof elastic cantilever circular piers were compared in the form of frequency domain transfer function,with the exact solutions which based on the radiation theory of incompressible non-viscous water considering structural deformation.Two kinds of size parameters were selected and 84 different sizes of piers were designed.By inputting impulse excitation,the transfer functions of displacement at the bottom,the transfer function of shear force and bending moment at the top were obtained.Then the first two order resonance-peak amplitude and resonance frequency were extracted for error analysis.Through the analysis of the range and variation trend of errors,it is found that:the resonance peak amplitude obtained by the rigid-structure method is more accurate,the resonance period obtained by the method based on approximation of fundamental-frequency is more accurate,and the error of the Morison method is significantly affected by the parameters.In addition,the amplitude of formant obtained by the fundamental frequency approximation is mostly smaller,while the amplitude and period obtained by the Morrison method are mostly larger.