A simplified procedure to proportion earthquake-resistant reinforced concrete structures without irregularities is presented. The flatrate method may also be used to assess the vulnerability of existing structures to earthquakes in a simple manner. The method is based on the concept that the maximum expected roof drift of a building is proportional to the ratio of total mass to stiffness of the lateral load resisting system. This method is not intended to provide sharp details about the expected performance of buildings but to evaluate the
