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Title |
A Study on Eccentricity in Low-Rise RC Piloti Buildings Considering the Shift of the Center of Rigidity under Inelastic Behavior
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Authors |
권유진(U-Jin Kwon) ; 백종하(Jong-Ha Paik) ; 백은림(Eun-Rim Baek) ; 이상호(Sang-Ho Lee) |
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DOI |
https://doi.org/10.11112/jksmi.2026.30.3.47 |
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Keywords |
강성중심; 비탄성 거동; 비선형 정적해석; RC 필로티 구조물; 비틀림 비정형; 비틀림 모멘트; 편심거리 Center of rigidity; Inelastic behavior; Non-linear static analysis; RC piloti buildings; Torsional irregularity; Torsional moment; Eccentricity |
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Abstract |
Low-rise reinforced concrete (RC) piloti buildings are vulnerable to seismic damage because of the vertical irregularity of the open first story.
When the core wall is placed eccentrically, torsional irregularity may also occur, causing displacement concentration and damage amplification in weak-side columns. However, current seismic design provisions generally evaluate torsional effects based on the elastic center of rigidity, which cannot fully reflect the inelastic shift of the center of rigidity caused by member yielding and damage. This study investigates the inelastic shift of the center of rigidity and the resulting increase in eccentricity in low-rise RC piloti buildings through one-directional nonlinear static pushover analyses. The main variables are the plan aspect ratio (AR), wall placement (W), wall-to-total rigidity ratio (R), and wall-to-total strength ratio (S). The results show that a higher wall strength ratio increases deformation concentration in weak-side columns, while a larger plan aspect ratio causes earlier column yielding under the same floor rotation. The center of rigidity moves continuously during the inelastic response, and its direction depends on the yielding sequence of the wall and columns. In some cases, the inelastic eccentricity increased up to 2.5 times the initial elastic eccentricity. These results show that the current elastic-rigidity-based evaluation cannot properly represent the actual torsional demand of torsionally irregular piloti structures. Therefore, this study discusses the need for an inelastic eccentricity ratio that reflects the effects of wall location, rigidity ratio, and strength ratio in practical torsional design.
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