We have developed the anchorless retrofitting method of our previous research, and clarified the shear transmission mechanism in retrofitted frames. The strength of retrofitted frame without anchors is composed of the column punching shear strength, shear friction between the existing reinforced concrete girders and steel frame, and the column shear strength. In this paper, we considered the shear friction between the existing reinforced concrete girders and steel frame, and evaluated the shear

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... friction as a coefficient multiplying the punching shear strength of the column. We performed FE analyses using concrete strength and span as parameters, and found that the ratio of the shear friction to story shear shared by steel brace is 0.35.. The method of evaluating the lateral strength of retrofitted frame without anchor was proposed, the average ratio of calculated values to experimental values was to be 1.33. We confirmed the safety of the proposed evaluation method.