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Title |
Seismic Performance Evaluation of the Vertical Extension Remodeling of Low-Rise Reinforced Concrete Frame Buildings Applying Seismic Isolation Systems
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Authors |
이하은(Ha-eun Lee) ; 우한수(Han-soo Woo) ; 허무원(Moo-won Heo) |
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DOI |
https://doi.org/10.4334/JKCI.2026.38.4.531 |
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Keywords |
수직증축; 리모델링; 면진 시스템; 경계비선형동적해석 vertically story-added; remodeling; seismic isolation system; boundary nonlinear dynamic analysis |
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Abstract |
With the recent increase in the frequency of earthquakes, securing the seismic performance of existing low-rise reinforced concrete (RC) structures has emerged as a critical issue. In particular, vertical extension remodeling entails an increase in the building’s mass and an elevation of its center of gravity, which can degrade the seismic performance of the existing structure, thereby necessitating a rational retrofitting strategy. This study investigates the effects of applying a seismic isolation system on the seismic performance of a low-rise RC structure built in the 1990s undergoing vertical extension. The seismic isolation device was designed using a combination of Lead Rubber Bearings (LRB) and Rubber Bearings (RB), with the target isolation period set to 2.0 seconds based on the design displacement. Subsequently, boundary nonlinear dynamic analyses were performed using seven input ground motions selected through a site response analysis, and the response characteristics of isolated and non-isolated structures were compared and analyzed. The analytical results indicate that while the overall displacement increased when the seismic isolation system was applied, the deformation was concentrated in the isolation layer, leading to effective control of the deformation of the superstructure. Furthermore, the maximum reponse acceleration was reduced by more than 70 %, the story shear force decreased by approximately 55 % compared to that of the non-isolated structrue, demonstrating that the seismic energy was effectively absorbed and dissipated within the isolation layer. In conclusion, the seismic isolation system was evaluated and found to be highly effective in reducing seismic responses and improving the seismic performance of the structure, even under the structurally disadvantageous conditions caused by vertical extension. Therefore, vertical extension remodeling utilizing a seismic isolation system is considered a practical alternative that can enhance the retrofitting efficiency while ensuring the structural safety of existing RC structures.
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