The purpose of this study is to propose the shear resisting mechanism and the evaluation formulas of shear strength for top slab of caisson foundation, which is RC deep slab simply supported at the all edges. Namely, the resisting model and the formulas for shear strength of top slab was studied from the internal stress and reaction force distribution of top slab varying configuration and shear span ratio and so on by means of FEM, under vertical force with or without eccentricity. Compared with the experimental results, the proposed formulas were demonstrated that they possessed high accuracy and simplicity. Finally, the application of this study to the limit state design of top slab was also referred.
