DETERMINATION OF ADDED MASS FOR EARTHQUAKE INDUCED HYDRODYNAMIC LOADINGS ON VERTICAL STRUCTURES

Earthquakes can induce severe hydrodynamic loadings on dams and their equipment. The dynamic dam-reservoir interaction is usually modelled by the so-called added mass. There are two theoretical approaches in the literature, employing either momentum or compressibility theory. Both assume zero pressures at the top of the structure, leading to comparatively low design pressures for control structures. A new theory was developed for a simple approximation for added mass and hydrodynamic pressures. The added mass is assumed to be uniform over the dam height. The added mass becomes a linear function of acceleration and water depth. Comparison with `classic' theories showed good agreement for accelerations up to 0.3g, and higher pressures for higher accelerations.