基于强震记录的二滩拱坝模态参数识别

Modal parameter identification of Ertan arch dam from strong earthquake records

结合二滩拱坝强震观测台阵在五次不同地震中的记录资料,分别利用频谱分析和时间序列分析,对大坝的频率、阻尼比、振型等模态参数进行了识别。从识别结果看,在地震对应的水位情况下,拱坝的一阶振型为对称振型,二阶振型为反对称振型;自振频率随水库水位的升高而降低,反映出附加质量增加带来的影响;前三阶阻尼比都不超过4%,也从另一个方面表明了地震造成的坝体响应不大,仍在线弹性范围内。

The modal parameters such as frequency, damping ratio and modal shape of Ertan arch dam are identified by using the dam responses under five different seismic excitations. The results indicate that the first mode is symmetric and the second anti-symmetric. Characteristic frequencies of the dam are decreased with the raise of reservoir level, which reflects the added mass effect. Damping ratio of the first three modes is quite small, no more than 4 %, which shows the linear elasticity of the dam response