Earthquake response of submerged circular cylinder

Abstract

The boundary integral method is utilized to calculate the dynamic response of a surface-piercing, vertical, circular cylinder subjected to high-frequency horizontal ground excitation. The cylinder is idealized as a one-dimensional beam of uniform flexural rigidity and uniform mass per unit length, the fluid is assumed linearly compressible and to undergo small-amplitude irrotational motion. The axisymmetry of the structure is exploited by utilizing a new Green's function for linearly compressible fluid flow which is separable in the cylindrical polar coordinate system, thus reducing the surface integral equation to a series of line integral equations. The motion of the cylinder may also be described in terms of a line integral equation through an appropriate Green's function. These two coupled line integral equations are then solved approximately by a numerical approach which involves discretising the region of integration and replacing the continuous problems by systems of algebraic equations which are then solved by standard matrix inversion techniques. Numerical examples are presented which show the influence of the frequency of ground excitation and the various geometric and material parameters on the hydrodynamic force and associated dynamic response of the cylinder.