Abstract: The 3-dimensional degenerated shell strip is applied to the non-linear analysis of slabs and shells structures.Geometric nonlinearity is included via the Von Kármán assumptions.By applying nonlinear constitutive models for concrete and reinforced bar to the shell strip,the geometric and material nonlinearity of reinforced concrete slabs and shells with varying thicknesses and arbitrary steel reinforcements can be analyzed.In nonlinear analysis,coupling between the different harmonic terms in stiffness matrix is removed according to 'quasi-stiffness-matrix method',which greatly simplifies the numerical computation.The effectiveness and accuracy of the present shell strip method is verified by two numerical examples.