• 한국지진공학회논문집
• /
• 제25권5호
• /
• pp.201-211
• /
• 2021

The Ministry of the Interior and Safety in Korea developed seismic fragility function for various building types in 2009. Damage states for most building types were determined by structural analyses of sample models and foreign references because actual cases damaged by earthquakes rarely exist in Korea. Low-rise, piloti-type buildings showed severe damage by brittle failure in columns due to insufficient stirrup details in the 2017 Pohang earthquake. Therefore, it is necessary to improve damage state criteria for piloti-type buildings by consulting actual outcomes from the earthquake. An analytical approach was conducted by developing analysis models of sample buildings reflecting insufficient stirrup details of columns to accomplish the purpose. The result showed that current spectral displacements of damage states for piloti-type buildings might be too large to estimate actual fragility. When the brittle behavior observed in the earthquake is reflected in the analysis model, one-fourth through one-sixth of current spectral displacements of damage states may be appropriate for existing low-rise, piloti-type buildings.

• 한국지진공학회논문집
• /
• 제26권2호
• /
• pp.49-58
• /
• 2022

The 2017 Pohang earthquake caused severe damage to low-rise piloti buildings. The damage was caused mainly by column shear failure, and some core walls were as well. The damaged piloti buildings in Pohang City could be relieved if they were designed correctly according to the standards at that time. However, the post-earthquake investigation revealed design, construction, and permission problems. To solve the problems, the Piloti Building Structure Design Guidelines that include strict specifications were published in 2018. Separately, KDS 41 17 00, the seismic design standard for buildings, was enacted in 2019 and it included the guideline contents. Therefore, at least after the publication of the guidelines, piloti buildings, designed by the standard and guidelines, can be expected to possess better seismic performance than existing piloti buildings. To confirm this, the probability of exceedance for several damage state thresholds was estimated for existing and designed piloti buildings. As a result, the probability of damage of designed piloti buildings was very low compared to existing ones. Consequently, it was confirmed that the guideline and standard adequately supplement the structural fragility of existing piloti buildings.

• 한국지진공학회논문집
• /
• 제25권6호
• /
• pp.251-259
• /
• 2021

Current seismic fragility functions for buildings were developed by defining damage state threshold based on story drift concerning foreign references and using the capacity spectrum method based on spectral displacement. In this study, insufficient details and dependence on the core location of piloti-type buildings were not reflected in the fragility function because it was developed before the Pohang earthquake. In order to develop an improved one for piloti-type buildings, several types of core were selected, damage state threshold was determined based on the capacity of structural members, and three-dimensional analyses were utilized. As a result, seismic fragility functions based on spectral acceleration were developed for various core locations and different shear strengths of the column stirrup. The fragility of piloti-type buildings significantly varied according to core location, an additional single wall, and whether the contribution of column stirrup was included or not. To estimate fragility more reasonably, it is necessary to prepare the parameters to reflect actual state well.

• 한국지진공학회논문집
• /
• 제28권4호
• /
• pp.171-181
• /
• 2024

For low-rise piloti-type buildings that suffered significant damage in the Pohang earthquake, the seismic performance of those designed by codes issued before and after the earthquake has been recently revised. This study started with the expectation that many of the requirements presented in the current codes may be excessive, and among them, the spacing of column stirrup could be relaxed. In particular, the recently revised design code of concrete structures for buildings, KDS 41 20 00, suggests that the column stirrup spacing is 1/2 of the minimum cross-sectional size or 200 mm, which is strengthened compared to KBC 2016, but relaxed than the current KDS, 41 17 00, which is 1/4 of the minimum size or 150 mm. As a result of the study, it was found that the target performance level was sufficiently satisfied by following the current standards and that it could be satisfied even if the relaxed spacing was followed. Therefore, the strict column stirrup spacing of KDS 41 17 00 could be relaxed if a wall other than core walls is recommended in the current guideline for the structural design of piloti-type buildings.

• 한국지진공학회논문집
• /
• 제22권3호
• /
• pp.161-168
• /
• 2018

Pohang earthquake occurred on November 15, 2017, with a magnitude of 5.4. The damage of the structure caused by the Pohang earthquake was the most significant in 4-story piloti-type buildings, where the damage patterns were different according to the location of columns and walls at the first story. One building with a staircase at a corner shows shear failure at columns, and Another building with a staircase in the middle shows no failure or shear failure at staircase walls. Therefore, two different piloti-type buildings were selected; one has a staircase at a corner and another has in the middle, and the seismic behavior of the buildings were examined by nonlinear dynamic analysis applying a ground motion measured at Pohang. Analytical model well simulated the actual behavior of the piloti-type buildings during the earthquake. Analysis results showed that walls have an insufficient shear strength wherever the location of the staircase is and columns with insufficient transverse reinforcement could be failed when the staircase is located at a corner. Conclusively, structural engineers should design columns and walls in piloti-type buildings to possess sufficient capacity according to the location of staircase.

• 한국전산구조공학회논문집
• /
• 제34권3호
• /
• pp.121-128
• /
• 2021

본 연구에서는 비틀림비정형성과 수직비정형성을 가진 RC 필로티 건축물의 지진동에 대한 거동을 층강성을 적용하여 간단하게 모델링하는 선형 동적해석 프로그램을 개발하고자 한다. 개발된 동적 해석 프로그램을 적용하여 필로티 건축물의 동적 거동 및 필로티층 각 기둥의 전단력을 분석하고, 필로티층에 전단벽 또는 가새를 보강하였을 때 보강효과를 평가하고자 한다. 모서리코어가 있는 필로티 건축물에서 필로티층의 코어 반대편 모서리를 전단벽이나 K형 가새로 보강하였을 때 변위와 기둥 전단력이 크게 감소하는 것으로 나타났으며, 모서리 양면을 K형 가새로 보강하는 것보다 한 면을 전단벽으로 보강하는 것이 보강효과가 큰 것으로 나타났다.

• 한국지진공학회논문집
• /
• 제23권1호
• /
• pp.31-42
• /
• 2019

In this study, the results of an analytical investigation on the seismic behavior of two residential 4-story bearing wall buildings with pilotis, each of which has symmetric or unsymmetric wall arrangement at their piloti level, are presented. The dynamic characteristics and lateral resistance of the piloti buildings were investigated through linear elastic and nonlinear static analyses. According to the results, the analytical natural period of vibration of the piloti buildings were significantly shorter than the fundamental period calculated in accordance with KBC 2016. In the initial elastic behavior, the walls resisting in-plane shear contributed to the lateral stiffness and strength, while the contribution of columns resisting flexural moments in double curvature was limited. However, after the shear cracking and yielding of the walls occurred, the columns significantly contributed to the residual strength and ductility. Based on those investigations, design recommendations of low-rise bearing wall buildings with piloti configuration are given.

• 대한건축학회논문집:구조계
• /
• 제35권12호
• /
• pp.137-148
• /
• 2019

Korean piloti-type buildings are comprised of pilotis in the first story and shear walls in the upper stories. This vertical irregularity causes excessive lateral plastic deformation on the first story while the upper stories stay elastic. Meanwhile, asymmetric position of structural components such as core walls and columns of RC piloti-type buildings tends to produce torsional irregularities of the structures. Korean Building Code(KBC2016) requires the special seismic load and torsional amplification factor to apply to the piloti-type buildings lower than six-story or 20m if it has vertical and torsional irregularities when the building corresponds to seismic design category C or D. Many Korean low-rised RC buildings fall into the class. Therefore, the special earthquake load and torsional amplification factor are often applied to a building simultaneously. However, it has not been studied enough how much influence each parameter has on buildings with vertical and torsional irregularities at the same time. The purpose of this study is to evaluate the effect of factor special seismic load and torsional amplification on seismic performance of irregular buildings. In this study, a damaged 4^th story piloti-type building by the Pohang earthquake was selected and the earthquake response analysis was carried out with various seismic design methods by the KBC 2016. The effect of the design parameters on seismic performance was analyzed by the dynamic analysis of models with special seismic load and torsional amplification factor based on the selected building. It was concluded that the application of the torsional amplification factor to the reference model to which special seismic design was applied, does not significantly affect the seismic performance.

• 토지주택연구
• /
• 제13권3호
• /
• pp.83-102
• /
• 2022

경주·포항 지진이후 국내 건축물의 내진성능에 대한 국민들의 관심이 고조되고 있으며, 특히 지진하중에 취약한 필로티형 건축물의 내진성능확보에 대한 시의성이 높아지고 있다. 이 연구에서는 LH가 보유한 필로티형 건축물의 유형별 내진보강방안을 제시하였다. 내진보강방안에는 내진보강우선순위, 코어의 위치에 따른 내진보강방안이 제시되어있다. 제시된 내진보강방안의 유효성을 검증하기 위하여 필로티형 건축물의 코어의 유형에 따라 전산해석을 수행하였으며, 그 결과 제시된 내진보강방안으로 내진보강을 수행 할 경우, 내진성능이 향상됨을 확인하였다.

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