INFLUENCE OF INDIRECT JOINT ON RETROFITTING EFFECT BY EXTERNAL STEEL FRAMES

An outside strengthening method for R/C buildings utilizing steel frames is proposed by the authors. A total of ten RC frames applying the proposed retrofitting method were tested to clarify the influence of indirect joints between the existing RC frames and steel frames on the retrofitting effect. As a result of the tests, it is indicated that grouting mortar in indirect joints contributes to a part of shear and axial loads, and is effective for preventing the existing RC columns from the shear failure. Also, the test results verified that the external steel frames are an effective method to retrofit and to delay brittle shear failure of existing RC columns, regardless of the presence of anchors fastened to existing RC columns.