The Equivalent Design Pressure of Ship Frame Structures Under Bottom Slamming Loads

Two-dimensional model drop tests were carried out to investigate slamming phenomena of a flat-inclined ship bottom in different drop heights. The water-entry velocities of the model, slamming pressures on the bottom and the resultant dynamic strains in the structures were recorded and the characteristic of the loads and structural responses were analyzed. To deduce design pressures for the frame structures, structural responses of the model under evenly distributed static pressures were calculated with the finite element method. Then, the experimental and calculated responses of the structures are compared with each other and a reduction factor is introduced to represent the relations of the two pressures. This reduction factor is linearly related to water-entry velocity and deadrise angle, and it could be used in the transformation of the measured slamming pressure peaks to equivalent design pressures in designing the frame structures of the bottom frames.