This paper deals with simplified structural analysis of single- and double-span rigid frame types of reinforced concrete bridges. A number of equations are proposed to compute the moments due to the live load, dead load, and earth pressure of rigid portal frame type bridges. By using a finite element program coded in this study, 479 highway bridges having different height, span length, and span ratios are analyzed. On the basis of the results of structural analysis, the equations to compute moments of rigid frame type bridges are derived based on the multi linear regression analysis. All the values of correlation factors obtained in this study are over 0.998 and the results obtained by the proposed equations generally show an excellent correlation with the results of finite element analysis. The proposed equations can be directly used to compute the moments of rigid frame type of bridges, if simplified analysis of highway bridge is necessary.