Abstract: Based on full-scale structural tests, the cyclic ice loads formed in crushing failure when ice interacts with vertical compliant structures are investigated. The results illustrate that three ice force modes, quasi-static, steady-state and random vibration, could be formed with the increase of ice speed. The mechanisms of the three ice force modes are analyzed. It is demonstrated that with the changing of ice speed, the loading rates of near field ice sheet, depending on the relative speed of ice and structure, can make ice fail in three forms, plastic failure, ductile-brittle transition failure and brittle failure. Explanations are given to describe the process of cyclic ice formation.