为探讨库水可压缩性在动力响应中的影响，以五嘎冲拱坝为例，采用三维有限元分析方法，进行地震动力时程分析，并将附加质量模型运算结果与其进行对比。计算结果表明，附加质量模型未考虑库水的可压缩性，降低了坝体的自振频率，夸大了动水压力的作用，对横河向和竖直向位移影响较小,增大了坝体顺河向位移；对拱向应力影响较小，但增大了坝体竖直向应力。

To explore the influence of the compressibility of reservoir water on the dynamic response, we carried out time-history analysis on the seismic dynamics of Wugachong arch dam using 3-D finite element model. Compared with the additional mass model, the model in the present study can better reflect the influence of reservoir water on the dynamic response. In the additional mass model, since the compressibility of reservoir water was not considered, the natural frequency of arch dam was lower and the hydrodynamic pressure was exaggerated. Changes of transverse and vertical displacements were little but the longitudinal displacement was increased, and the change of  stress in arch direction was little while the vertical stress was increased. 