A new seismic retrofitting technique using compressive bracings for existing piloti-type reinforced concrete (R/C) frames has been proposed. The bracing is composed of steel pipes filled with high-strength mortar with its ends being able to resist only compressive force. This makes carrying out seismic retrofit easier, lowers the cost, and also minimizes the time spent. A model is proposed in this paper to predict the envelop curve of lateral load versus story drift angle in the strengthened story after employing the compressive bracings. Calculations are presented to predict the axial stiffness and axial strength of the bracing, as well as the bearing strength and the partial bearing stiffness of the beams jointed to the bracing. Comparison between the experimental and theoretical values shows that the theoretical values predict the experimental values reasonably accurate.