【摘要】 建立考虑水-结构-土相互作用的桥墩结构自振频率半解析解，并通过实测数据进行验证。以单个桥墩为研究对象，将“桥墩-承台-桩基”结构体系简化为Bernoulli-Euler梁，采用附加质量模型模拟水-结构相互作用，采用弹性Winkler地基模型模拟桩-土相互作用，建立考虑水-结构-土相互作用的桥墩结构振动控制方程。使用分离变量法得到结构振型函数，根据边界条件建立矩阵方程，通过求解方程的特征值得到结构自振频率。以福州浦上大桥E11桥墩为例，将海底地震仪(ocean bottom seismometer, OBS)核心地震计安装在承台处，采集桥墩的振动响应并提取结构自振频率。同步安装陆地地震仪验证OBS水下监测的有效性，通过对比半解析解、有限元解和实测值验证桥墩结构半解析解的合理性。在此基础上，分析土-结构相互作用、水-结构相互作用对结构自振频率的影响。结果表明，OBS能够满足桥墩自振频率水下测试的环境要求；建立的考虑水-结构-土相互作用的桥墩结构自振频率半解析解合理；土-结构、水-结构相互作用会降低结构的一阶自振频率，其中土-结构相互作用的影响比水-结构相互作用更显著。更多还原

【Abstract】 Here, a semi-analytical solution to natural frequencies of bridge pier structure was established considering water-structure-soil interaction, and it was verified with actually measured data. Taking a single bridge pier as the study object, a "pier-cushion cap-pile foundation" structural system was simplified as a Bernoulli-Euler beam. The additional mass model was used to simulate water-structure interaction, and the elastic Winkler foundation model was used to simulate pile-soil interaction. The vibration governing equation of a bridge pier structure considering water-structure-soil interaction was established. The separating variables method was used to obtain structural vibration modal functions, the eigen matrix equation was established based on boundary conditions, and by solving eigenvalues of the eigen matrix equation, structural natural frequencies were obtained. Taking the E11 pier of Fuzhou Pushang Bridge as an example, the core seismometer of ocean bottom seismometer(OBS) was installed at the pier’s cushion cap to collect vibration response signals of the pier and extract natural frequencies of the structure. Simultaneously, a land seismometer was installed to verify the effectiveness of OBS underwater monitoring. By comparing the semi-analytical solution, finite element solution and actually measured values, the rationality of the semi-analytical solution of the bridge pier structure was verified. Finally, effects of soil-structure interaction and water-structure interaction on natural frequencies of the structure were analyzed. The results showed that OBS can meet environmental requirements for underwater testing of natural frequencies of bridge pier; the semi-analytical solution to natural frequencies of bridge pier structure considering water-structure-soil interaction established here is reasonable; soil-structure interaction and water-structure interaction can reduce the 1st order natural frequency of the structure where affecting of soil-structure interaction is more significant than that of water-structure interaction.更多还原