This paper presents comparison among different nonlinear seismic analysis methods, i.e. pushover analyses include Modal pushover analysis (MPA) and N2 method, in addition to nonlinear dynamic analyses include nonlinear time history (NLTH) methods. by using both of Matlab and Sap2000 computer programs. The NLTH-sap2000 is considered the major method, while the rest methods are compared to it. The underlying concept of each studied nonlinear analysis method is outlined and step-by-step. procedure is summarized. Applications have performed for two RC building frames. The accuracy and reliability of MPA and N2 in estimating the peak responses of the global and the local seismic demands is evaluated and compared with the same values. resulted in the (NLTH) analyses methods. Based on that N2 method is considered a practical alternative method for the nonlinear time-history analysis, the effect of the applied lateral load pattern type by the N2 method is studied by exploring five different types. NLTH programming in MATLAB is introduced for tending to future studies with acceptable accuracy in the use of diverse parameters. The results are presented and discussed