This study proposes a seismic retrofitting method using a concrete-filled steel tube frame (CSTF) system, a novel technique to improve the limitations of existing seismic strengthening methods. The CSTF method makes the most of the advantages of both concrete and steel pipes, thereby significantly i...
This study proposes a seismic retrofitting method using a concrete-filled steel tube frame (CSTF) system, a novel technique to improve the limitations of existing seismic strengthening methods. The CSTF method makes the most of the advantages of both concrete and steel pipes, thereby significantly improving constructability and increasing integration between the existing structure and the reinfoR/Cement joints. This method falls into the category of typical seismic retrofitting methods that focus on increasing strength, in which the required amount of seismic reinfoR/Cement can be easily estimated. Therefore, the method provides an easy solution to improving the strength of existing reinforcrd concrete (R/C) structures with non-seismic details that are prone to shear failure. In this study, a full-size two-story frames modeled from existing R/C structures with non-seismic details was subjected to pseudo-dynamic testing. As a result, the effect of the CSTF system, when applied to existing R/C structures, was examined and verified, especially as to its seismic retrofitting performance, i.e., restoring force characteristics, stiffness reinforcement, and seismic response control. The results showed that the RC frame with no retrofitting measures applied underwent shear failure at a seismic intensity of 200 cm/s2, the threshold applied in seismic design in Korea. In contrast, in the frame retrofitted with the CSTF system, only minor earthquake damage was observed, and even when the maximum seismic intensity (300 cm/s2) that may occur in Korean was applied, small-scale damage was observed. These results confirmed the validity of the seismic retrofitting method based on the CSFT system developed in the present study.
This study proposes a seismic retrofitting method using a concrete-filled steel tube frame (CSTF) system, a novel technique to improve the limitations of existing seismic strengthening methods. The CSTF method makes the most of the advantages of both concrete and steel pipes, thereby significantly improving constructability and increasing integration between the existing structure and the reinfoR/Cement joints. This method falls into the category of typical seismic retrofitting methods that focus on increasing strength, in which the required amount of seismic reinfoR/Cement can be easily estimated. Therefore, the method provides an easy solution to improving the strength of existing reinforcrd concrete (R/C) structures with non-seismic details that are prone to shear failure. In this study, a full-size two-story frames modeled from existing R/C structures with non-seismic details was subjected to pseudo-dynamic testing. As a result, the effect of the CSTF system, when applied to existing R/C structures, was examined and verified, especially as to its seismic retrofitting performance, i.e., restoring force characteristics, stiffness reinforcement, and seismic response control. The results showed that the RC frame with no retrofitting measures applied underwent shear failure at a seismic intensity of 200 cm/s2, the threshold applied in seismic design in Korea. In contrast, in the frame retrofitted with the CSTF system, only minor earthquake damage was observed, and even when the maximum seismic intensity (300 cm/s2) that may occur in Korean was applied, small-scale damage was observed. These results confirmed the validity of the seismic retrofitting method based on the CSFT system developed in the present study.
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