• Structural Engineering and Mechanics
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• 제47권6호
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• pp.791-818
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• 2013

The seismic performance of reinforced concrete (RC) frame structures with irregularities leading to soft first floor is studied using capacity assessment procedures. The soft first story effect is investigated for the cases: (i) slab-column connections without beams at the first floor, (ii) tall first story height and (iii) pilotis type building (open ground story). The effects of the first floor irregularity on the RC frame structure performance stages at global and local level (limit states) are investigated. Assessment based on the Capacity Spectrum Method (ATC-40) and on the Coefficient Method (FEMA 356) is also examined. Results in terms of failure modes, capacity curves, interstory drifts, ductility requirements and infills behaviour are presented. From the results it can be deduced that the global capacity of the structures is decreased due to the considered first floor morphology irregularities in comparison to the capacities of the regular structure. An increase of the demands for interstory drift is observed at the first floor level due to the considered irregularities while the open ground floor structure (pilotis type) led to even higher values of interstory drift demands at the first story. In the cases of tall first story and slab-column connections without beams soft-story mechanisms have also been observed at the first floor. Rotational criteria (EC8-part3) showed that the structure with slab-column connections without beams exhibited the most critical response.

• 한국공간구조학회논문집
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• 제18권2호
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• pp.59-67
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• 2018

Various pilotis are installed in the lower part of high rise buildings. Strong winds can generate sudden airflow around the pilotis, which can cause unexpected internal airflow changes and may cause damage to the exterior of the piloti ceiling. The present study investigates the characteristics of peak wind pressure coefficient for the design of piloti ceiling exteriors by conducting wind pressure tests on high rise buildings equipped with penetration-type and end-type pilotis in urban and suburban areas. The minimum peak wind pressure coefficient for penetration-type piloti ceilings ranges from -2.0 to -3.3. Minimum peak wind pressure coefficient in urban areas was 30% larger than in suburban areas. In end-type piloti ceilings, maximum peak wind-pressure coefficient ranges from 0.5 to 1.9, and minimum peak wind-pressure coefficient ranges from -1.3 to -3.6. With changes in building height, peak wind pressure coefficient decreases as the aspect ratio increases. Peak wind-pressure coefficient increases with taller pilotis. On the other hand, when piloti height decreases, the absolute value of the minimum peak wind pressure coefficient increases.

• Earthquakes and Structures
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• 제22권4호
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• pp.345-353
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• 2022

The configuration of an open ground floor (pilotis) is a common and very critical irregularity observed in multistory reinforced concrete frame structures. The characteristics and the geometrical formation of the beams of the first story proved to be a critical parameter for the overall seismic behavior of this type of Reinforced Concrete (RC) structures. In this work the combination of open ground floor (pilotis) morphology with very strong perimetrical beams at the level of the first story is studied. The observation of the seismic damages and the in situ measurements of the fundamental period of four buildings with this morphology and Π-shaped plan view are presented herein. Further analytical results of a pilotis type Π-shaped RC structure are also included in the study. From the measurements and the analytical results yield that the open ground floor configuration greatly influences the fundamental period whereas this morphology in combination with strong beams can lead to severe local shear damages in the columns of the ground floor. The structural damage was limited in the columns of the ground floor and yet based on the changes of the in situ measured fundamental period the damaged level is assessed as DI=88%. Furthermore, due to the Π-shape of the plan view the tendency of the parts of the building to move independently strongly influences the distribution of the damages over the ground floor vertical elements.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.959-969
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• 2011

본 연구는 임대주택의 구조방식이 벽식구조에서 라멘구조로 변화하는 시점에서 서울시 임대주택의 필로티공간계획의 주안점을 모색하고자 하였다. 이를 위해 서울시 임대주택의 현황을 분석하고 연구대상으로 선정된 7개 단지 28개동에 대해서 물리적, 공간적, 환경적 분석 및 사용자 면담을 실시하였다. 이를 통해 벽식구조 필로티 공간의 문제점을 인식하고 라멘구조로 전환시에 계획의 주안점을 다음과 같이 제시하였다. 첫째, 필로티 공간의 유효면적 증가와 쾌적성 향상에 따른 공간 활용의 다양성에 대응하기 위한 계획적 접근이 필요하다. 둘째, 필로티 공간의 특성상 다양한 기능이 복합되는 경우 기능의 경계를 명확히 구분하여 간섭과 충돌을 최소화하고 기능이 불명확한 공간으로 방치되지 않도록 계획하여야 한다. 셋째, 실내공간으로 전용가능성을 고려해야 한다. 상대적으로 외부공간이 부족한 임대주택에서 필로티 공간을 적극적으로 활용해야 하며 거주자의 다양한 요구를 수용하기 위해 이를 고려한 구조체배치 등의 계획적 접근이 요구된다. 넷째, 안전성을 확보해야 한다. 필로티 공간과 외부공간과의 시각적 연결관계를 고려해서 필로티 공간이 외부로부터 고립되지 않도록 계획하여야 한다.

• Earthquakes and Structures
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• 제6권1호
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• pp.89-110
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• 2014

Nonlinear dynamic analyses are carried out to investigate the influence of the pinching hysteretic response of the exterior RC beam-column joints on the seismic behavior of multistory RC frame structures. The effect of the pinching on the local and global mechanisms of an 8-storey bare frame and an 8-storey pilotis type frame structure is evaluated. Further, an experimental data bank extracted from literature is used to acquire experimental experience of the range of the real levels that have to be considered for the pinching effect on the hysteretic response of the joints. Thus, three different cases for the hysteretic response of the joints are considered: (a) joints with strength and stiffness degradation characteristics but without pinching effect, (b) joints with strength degradation, stiffness degradation and low pinching effect and (c) joints with strength degradation, stiffness degradation and high pinching effect. For the simulation of the beam-column joints a special-purpose rotational spring element that incorporates the examined hysteretic options developed by the authors and implemented in a well-known nonlinear dynamic analysis program is employed for the analysis of the structural systems. The results of this study indicate that the effect of pinching on the local and global responses of the examined cases is not really significant at early stages of the seismic loading and especially in the cases when strength degradation in the core of exterior joint has occurred. Nevertheless in the cases when strength degradation does not occur in the joints the pinching may increase the demands for ductility and become critical for the columns at the base floor of the frame structures. Finally, as it was expected the ability for energy absorption was reduced due to pinching effect.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.761-770
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• 2017

본 연구는 근린재생이 필요한 저층밀집주거지역의 연립주택 하부 필로티 공간을 대상으로 커뮤니티 활동을 수용할 수 있는 방안을 제안하는데 목적이 있다. 협소한 주차공간에 미치는 영향을 최소화하기 위해, 벽식 구조는 배제하고, 필로티의 기둥 사이 유휴공간에 수요자 요구시설을 모듈(Prefabricated frame)을 설치하여 활용할 수 있는 계획을 제안하였다. 모듈을 사용할 경우, 단기간에 미리 제작된 프레임을 조립하는 방식으로 공기단축, 비용절감은 물론 소음 등으로 인한 민원발생을 최소화할 수 있다는 장점이 있기 때문이다. 또한 거주자 요구에 따라 다른 형태로 축소, 확대한 프레임을 연결할 수 있다는 측면에서 긍정적인 효과를 기대할 수 있다. 거주자 면담조사와 필로티 실태 조사를 통해 택배보관소, 휴게공간, 문화 공간, 쓰레기 처리 공간 등이 필요로 하다는 것을 도출할 수 있었다. 이를 해소하기 위해 본 연구에서 제안한 모듈은 4가지로, 삼각모듈, 퍼즐모듈, 박스모듈, 경첩모듈이다. 각각의 장점과 단점을 정리하고, 향후 보완방향을 제안함으로써 활용 가능성을 시사하였다.