In this work we will explain a new methodology that have been utilized in a new software package (program) to determine the lateral loads at which a 3D reinforced concrete frame building collapses. The solution is represented by forming the capacity curve (force-displacement) of the structure taking into account the elastic-plastic behavior of the element materials represented by plastic hinges positioned at the ends of the linear elements. This work takes into account only the plastic hinges caused by bending moments. The program is based on finite elements method and capable of analyzing and designing three dimensions buildings. The program provides a drawing environment (3D view, plan view, elevation view) with tools to create the model and to perform the structural analysis and design.