ScholarWorks@성균관대학교

초록

This study proposes a novel seismic retrofitting method to address the limitations of conventional strength-based techniques. The proposed welded modular base plate system (WMBPS) connects a retrofit steel frame to an existing reinforced concrete (R/C) frame using welded modular base plates with chemical anchors, optimized Tshaped connectors, and high-strength non-shrink mortar, thereby forming an integrated load-resisting system. The WMBPS effectively enhances the lateral load resistance of shear-critical R/C buildings without seismic detailing, while reducing construction errors, shortening construction time, and simplifying the estimation of required strengthening capacity. To verify the seismic performance of the WMBPS, cyclic loading tests were conducted on conventional and WMBPS joints, and pseudo-dynamic tests were performed on a full-scale, twostory R/C frame with non-seismic detailing. In addition, nonlinear static and dynamic finite element analyses were carried out to validate the experimental results. The cyclic loading tests showed that the WMBPS joint achieved a maximum load capacity of 195 kN, approximately twice that of the conventional joint (98 kN), while maintaining comparable displacement capacity. Under a design-basis earthquake (DBE, 200 cm/s2), the unretrofitted frame exhibited brittle shear failure with a peak displacement of 66.5 mm, whereas the WMBPSretrofitted frame showed only minor damage with a peak displacement of 6.1 mm, corresponding to a displacement reduction of approximately 90%. Even under a maximum considered earthquake (MCE, 300 cm/s2) and a larger seismic input (400 cm/s2), the retrofitted frame maintained stable behavior with moderate damage. The seismic response strength of the WMBPS-retrofitted frame increased by up to 3.3 times compared with the unretrofitted frame. The nonlinear FEAs reproduced the experimental responses with discrepancies of less than 10% in peak load and displacement. These results demonstrate that the proposed WMBPS provides an effective and reliable solution for seismic retrofitting of shear-critical R/C buildings.

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