A simplified method is presented for calculation of the natural frequencies of RC buildings braced by frameworks, coupled shear wall, shear walls and cores. The method is for structures that have uniform properties through their height, and that are symmetrical in plan so that they do not twist. Lateral vibration is characterised by the three types of deformation: the full-height 'local' bending of the individual columns/wall sections/shear walls/cores, the full-height 'global' bending of the frameworks due to the axial deformation of columns, and the shear deformation of the frameworks. It needs combination of each deformation type and complex calculations to estimate the dynamic properties such as natural frequency. For simple calculation of the lateral frequencies, the degree of stiffness contribution is formulated in this study and compared to FEM analysis.