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Title |
Effects of Strength and Plan Aspect Ratios on the Inelastic Behavior of Low-rise RC Piloti Buildings with Torsional Irregularity
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Authors |
권유진(U-Jin Kwon) ; 백종하(Jong-Ha Paik) ; 이상호(Sang-Ho Lee) ; 백은림(Eun-Rim Baek) |
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DOI |
https://doi.org/10.11112/jksmi.2025.29.5.114 |
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Keywords |
강도중심; 비선형 정적해석; RC 필로티 구조물; 비틀림 비정형; 비틀림 모멘트 Center of strength; Non-linear static analysis; RC piloti buildings; Torsional irregularity; Torsional moment |
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Abstract |
Low-rise reinforced concrete (RC) piloti buildings are highly vulnerable to torsion due to the eccentric placement of core walls, a fact confirmed by numerous failures during the 2017 Pohang earthquake. This study aims to identify the actual inelastic collapse mechanism of piloti buildings and to propose key design parameters for ensuring their seismic safety. To achieve this, a three-dimensional non-linear static analysis (push-over) is performed with the wall-to-column strength ratio (S) and the planar aspect ratio (AR) as the main variables. The results of this study showed that the collapse mechanism was dominantly governed by the strength ratio rather than the initial static eccentricity. When the strength ratio was low (S≤4), a stable, ductile failure was induced by the wall yielding first, which effectively controlled the torsional behavior. In contrast, when the strength ratio was high (S≥6), an unstable, brittle failure occurred due to the premature yielding of weak-side columns, which amplified the torsional response. This difference in collapse mechanisms was clearly identified by the post-yield movement direction of the center of strength (CS). In models with a low strength ratio, the CS moved inward toward the center of mass (CM), indicating a balanced strength distribution. Conversely, in models with a high strength ratio, the CS moved outward, indicating a worsening of the strength imbalance. These models with excessively high strength ratio and aspect ratio failed prematurely without achieving their designed strength. Therefore, it is essential to move beyond static indices like initial eccentricity. Instead the design should focus on controlling the failure sequence by maintaining a wall-to-column strength ratio of 2.0 or less.
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