LAUSR

The analytical method was adopted to investigate the earthquake-induced hydrodynamic pressure on a circular cylinder surrounded by two-layer fluid. Based on the radiation theory, the analytical expressions of hydrodynamic pressure, hydrodynamic force on a rigid circular cylinder were obtained. Then, the dispersion relation for radiation problem in a two-layer fluid, and the added mass and damping coefficients on the circular cylinder in the case were analyzed. The earthquake-induced hydrodynamic forces on the circular cylinder in a two-layer fluid were furtherly investigated. It is founded that the hydrodynamic pressures on the circular cylinder include not only the surface-wave and perturbing wave modes, but also the internal-wave mode. This is quite different from the case of a single-layer fluid. However, the results indicate that the internal-wave mode has little influence on the hydrodynamic forces on the circular cylinder in two-layer fluid. Lastly, seismic responses of the flexible cylinder in single-layer and two-layer fluid were studied. Some examples show that the seismic responses of the cylinder in two-layer fluid are much larger than these in single-layer fluid.