Earticle

This research proposed a seismic strengthening technique of Pre-stressing Steel Frame methodology (PSF) for existing R/C buildings in order to enhance the connection performance and constructability. The PSF system, proposed in this study, is a type of strength-enhancing reinforcement systems to easily increase the ultimate horizontal shear capacity of R/C structures without seismic details. The PSF method increased the seismic reinforcement effect and constructability by separating the reinforcement H-frames into two parts for improving the integration of connections between the existing R/C frame and the strengthening member by using pre-stressing technique. Two test specimens of full-size two-story R/C frames were fabricated based on an existing domestic R/C building without seismic details, and then retrofitted by using the proposed PSF seismic system. Pseudo-dynamic testing was conducted to evaluate seismic rehabilitation effects, and the seismic response characteristics of the proposed system, in terms of the maximum shear force, response story drift, and seismic damage degree compared to the control specimen without strengthening frame. Test results revealed that the proposed PSF reinforcement system effectively enhanced the horizontal shear force, resulting in reduced story drift of R/C buildings under the maximum design earthquake level designated in KDS 41.

In this study, in order to enhance the connection performance between the existing reinforced concrete (R/C) frame and the strengthening member, we proposed a novel concept of CFT External Composite Methodology (CECM) for seismic retrofit of existing domestic medium-to-low-rise R/C buildings. The CECM method, proposed in this study, can conduct the seismic retrofitting construction while residents can live inside building. The CECM rehabilitation system is a type of strength-enhancing reinforcement systems, to easily increase the ultimate horizontal shear capacity of R/C structures without seismic details in Korea, which show shear collapse mechanism. Two test specimens of full-size two-story R/C frame were fabricated based on an existing domestic R/C building without seismic details, and then retrofitted by using the proposed CECM seismic system; therefore, one control test specimen and one test specimen reinforced with the CECM system were used. Pseudo-dynamic testing was conducted to evaluate seismic strengthening effects, and the seismic response characteristics of the proposed system, in terms of the maximum shear force, response story drift, and seismic damage degree compared with the control specimen (R/C bare frame). Experiment results indicated that the proposed ECCM reinforcement system, externally installed to the existing R/C frame, effectively enhanced the horizontal shear force, resulting in reduced story drift of R/C buildings under the maximum design earthquake level designated in KDS 41.