In cold regions, changes in water level can induce vertical forces on offshore structures (such as caisson and tower types) when sea ice cover to structure adfreeze bonding is present. This paper summarized the theoretical analyses of vertical ice forces as well as the results of experiments which identified the parameters required when estimating sea ice adfreeze bond strength. 1 ) Vertical Ice Forces. The authors have proposed a method of calculation that estimates the vertical ice forces taking the following into account: bending failure of the ice cover and adfreeze bond failure (shear induced). Calculation of vertical ice forces by this method requires the following information: bending strength of ice. Young’s modulus of ice, Poisson’s ratio of ice, and adfreeze bond strength to various materials. 2 ) Adfreeze Bond Strength of Sea Ice. The authors have been conducting, for 6 yr, adfreeze bond strength experiments between sea ice and various common construction materials for offshore structures such as concrete and steel. The following conclusions have been drawn from this study: (i ) under certain conditions, the adfreeze bond strength of sea ice greatly depends on the surface roughness of construction materials; (ii ) adfreeze bond strength increases with decreasing sea ice temperature; (iii ) adfreeze bond strength decreases, approaching a constant, with increasing structure diameter; (iv ) adfreeze bond strength increases, approaching a constant, with increasing ice thickness; (v ) adfreeze bond strength is not greatly affected by push out velocity and stress rate.