Wave impact on elastically supported horizontal deck

Laboratory experiments supported by theoretical investigations were applied to study the wave impact on a horizontal deck, deck vibrations, and phenomena related to wave-induced vibrations. The analysis shows that one can distinguish four characteristic stages of deck vibrations between two consecutive wave impacts. In the first stage, the wave impact induces very high-frequency waves in the deck structure and in the wave flume. There are important components with acoustic frequencies. In the second stage, the deck vibrates in contact with water. The frequencies of vibrations in water are much lower than the corresponding frequencies of the free vibrations in air. The third stage of wave-induced vibrations is a transitional one. At the beginning of the third stage, the deck vibrates in contact with water and at the end of this stage it vibrates in air as a free rigid body. In this process water is shed from the deck. Sometimes the process of shedding is violent, which induces high-frequency vibrations with relatively large amplitudes. The fourth stage of wave-induced vibrations corresponds to the free vibrations of the deck in air. Similar four stages can be distinguished in the pressure records. Additional information regarding wave impact on the deck and the phenomena related to the impact can be obtained by the analysis of mechanical energy. The analysis of mechanical energy is especially helpful in understanding dissipation processes and phenomena in the transitional stage of wave-induced vibrations. In particular, the analysis of energy explains why the amplitudes of acceleration are increasing in the transitional stage of wave-induced vibrations.