The aim of this paper is the evaluation of an existing RC multistory building if exposed to seismic loads. The building studied is a four storey residential building in the city of Cairo, Egypt. It is constructed from reinforced concrete and designed for gravity loads only according to the Egyptian Concrete Code EGP203-2018. In the present paper earthquake loads are calculated by three different methods (Equivalent Static method, Response Spectrum method, Time History Analysis). These methods are given in the Regulations for earthquake resistant design of buildings in Egypt, (EGP203-2018). The results from the analysis due to seismic and gravity loads are compared in order to evaluate the straining actions of base shear. The bending moment and shear forces can be obtained from ETABS 17.0.1, which is usually used to perform the linear and nonlinear analysis. The results showed there is effect for seismic loads in the X direction and also the paper studied the effect of seismic loads in the Y direction. Generally Bending moments and shear forces in beams
and columns due to seismic excitation showed much larger values compared to that due to gravity loads .The results obtained, show the need for additional reinforcements and increase of cross sections of the original concrete elements, in order to improve its seismic behavior.