Abstract: The upper structure and foundation of offshore wind turbines (OWTs) bear huge lateral environmental loads over the life time. Meanwhile, there is a high probability of the seismic load acting on the foundation of OWTs simultaneously. In this paper, a loading device was designed to impose initial lateral environmental loads, and a set of centrifuge dynamic model tests on a monopile in sand ground were setup. Thus, the monopile dynamic tests under jointed load condition were realized from the physical model scale. The centrifuge shaking table test shows that the bending moment of the pile after shaking under jointed load conditions is greater than its initial bending moment. The bending moment of the pile after the earthquake at a partial depth in the saturated sand is about four times than the initial bending moment. In addition, it is found that the lateral displacement at the pile head accumulated during the shaking process. The lateral displacement of the pile head after the earthquake is 1.3 times of the initial lateral displacement. The coupling effect of monopile for offshore wind turbines under jointed load condition poses a great challenge to the safe service of OWTs and deserves attention in the design of OWTs foundation.

Key words: static shear stress, offshore wind turbine, monopile, centrifuge shaking table