This study presents an approximate method which is based on the continuum approach and one dimensional finite element method to be used for lateral static and dynamic analyses of wall-frame buildings. In this method, the whole structure is idealized as an equivalent sandwich beam which includes all deformations. The effect of shear deformations of walls is considered and incorporated in the formulation of the governing equations. Initially the differential equations of this equivalent sandwich beam are written; then shape functions and stiffness matrix can be obtained by solving the differential equations. For static and dynamic analysis the lateral forces and masses were applied on the storey levels. Angular frequency and modes were obtained by using system mass and system stiffness matrices. Finally, numerical examples have been solved using MATLAB to verify the presented method. The results of these examples display the agreement between the proposed method existing methods.