• 한국지진공학회논문집
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• 제17권5호
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• pp.197-207
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• 2013

The seismic performance of school buildings has been a matter of common interest socially and academically. The structural system of the school buildings is representative of the domestic low-rise reinforced concrete moment resisting frames, which apply extensively infills in their masonry walls. The masonry infilled walls are divided into full masonry infill in the transverse direction and partial masonry infill in the longitudinal direction. The masonry infilled walls are usually not included in structural analysis during the design process, but affect significantly the seismic performance because they behave with surrounding frames simultaneously during earthquakes. Many researchers have studied the effect of the masonry infilled walls, but several issues have been missed such as the increase of asymmetry by adding the full masonry infill, the size of the mean strength of the full masonry infill, and short column effect by the partial masonry infill. The issues were analytically investigated and the results showed that they should be checked at least by nonlinear pushover analysis in the seismic performance evaluation process. The results also confirm the weakness of the guideline of Korean Educational Development Institute where the seismic performance is basically assessed without structural analysis.

• 한국지진공학회논문집
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• 제24권1호
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• pp.39-47
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• 2020

Lightly reinforced concrete (RC) moment frames may suffer significant damage during large earthquake events. Most buildings with RC moment frames were designed without considering seismic loads. The load-displacement response of gravity load designed frames could be altered by masonry infill walls. The objective of this study is to investigate the load-displacement response of gravity load designed frames with masonry infill walls. For this purpose, three-story gravity load designed frames with masonry infill walls were considered. The masonry infilled RC frames demonstrated larger lateral strength and stiffness than bare RC frames, whereas their drift capacity was less than that of bare frames. A specimen with a partial-height infill wall showed the least drift capacity and energy dissipation capacity. This specimen failed in shear, whereas other specimens experienced a relatively ductile failure mode (flexure-shear failure).

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.483-489
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• 2008

Masonry infill walls are frequently used as interior partitions and exterior walls in low- or middlerise RC buildings In the structural design and assessment of structural behaviors of buildings, the infill walls are usually treated as non-structural elements and they are ignored in analytical models. In this study, seismic behaviors of RC frame with/without masonry infill walls were investigated. To this end, the infill walls were modeled as equivalent diagonal struts. Based on analytical results, it has been shown that masonry infill walls can increase the global strength and stiffness of a structure. Accordingly, inter-story drift ratio will be decreased but seismic forces applied to the structure were increased than design seismic load because natural period of the structure was decreased. It is also seen from the analytical results that the inelastic deformation of RC frame with soft story is concentrated on the first story columns and thus, partial damage may have possibility of collapse of system.

• Earthquakes and Structures
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• 제12권3호
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• pp.333-347
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• 2017

Masonry infill walls are unavoidable parts of any building to create a separation between internal space and external environment. In general, there are some prevalent openings in the infill wall due to functional needs, architectural considerations or aesthetic concerns. In current design practice, the strength and stiffness contribution of infill walls is not considered. However, the presence of infill walls may decisively influence the seismic response of structures subjected to earthquake loads and cause a different behavior from that predicted for a bare frame. Furthermore, partial openings in the masonry infill wall are significant parameter affecting the seismic behavior of infilled frames thereby decreasing the lateral stiffness and strength. The possible effects of openings in the infill wall on seismic behavior of RC frames is analytically studied by means of pushover analysis of several bare, partially and fully infilled frames having different bay and story numbers. The stiffness loss due to partial opening is introduced by the stiffness reduction factors which are developed from finite element analysis of frames considering frame-infill interaction. Pushover curves of frames are plotted and the maximum base shear forces, the yield displacement, the yield base shear force coefficient, the displacement demand, interstory drift ratios and the distribution of story shear forces are determined. The comparison of parameters both in terms of seismic demand and capacity indicates that partial openings decisively influences the nonlinear behavior of RC frames and cause a different behavior from that predicted for a bare frame or fully infilled frame.

• 한국지진공학회논문집
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• 제14권5호
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• pp.13-22
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• 2010

철근콘크리트 건축물에서 비내력벽(Masonry Infill Walls)은 내부 칸막이벽이나 중저층 규모의 건물 외벽에 흔히 사용된다. 그렇지만 대부분의 경우에 비내력벽은 비구조체이므로 구조설계시 건물의 모형화에서 무시된다. 따라서 본 연구에서는 비내력벽을 보편화된 모형화 방법인 등가의 대각 압축 스트럿(Equivalent Diagonal Strut)으로 고려하여 비내력벽의 유무에 따른 저층 철근콘크리트 건축물의 전체적인 지진거동의 양상을 평가하고자 하였다. 해석결과로 비내력벽을 고려하면 시스템의 추가적인 강도 및 강성을 확보하여 층간변위비를 줄일 수 있으나 진동주기가 짧아져서 설계단계에서 고려한 지진하중보다 큰 하중을 받게 된다. 연약층이 있는 모델의 경우에는 기둥에 소성거동이 집중됨을 알 수 있으며 부분적인 붕괴가 전체 시스템의 붕괴 원인의 가능성을 가진다.

• 한국지진공학회논문집
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• 제23권1호
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• pp.71-82
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• 2019

Most school buildings consist of reinforced concrete (RC) moment frames with masonry infills. The longitudinal direction frames of those school buildings are relatively weak due to the short-column effects caused by the partial masonry infills and need to be evaluated carefully. In 'Manual for Seismic Performance Evaluation and Retrofit of School Facilities' published in 2018, response modification factor of 2.5 is applied to non-seismic RC moment frames with partial masonry infills, but sufficient verification of the factor has not been reported yet. Therefore, this study conducted seismic performance evaluation of planar RC moment frames with partial masonry infills in accordance with both linear analysis and nonlinear static analysis procedures presented in the manual. The evaluation results from the different procedures are compared in terms of assessed performance levels and number of members not meeting target performance objectives. Finally, appropriate response modification factors are proposed with respect to a shear-controlled column ratio.

• 한국지진공학회논문집
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• 제23권4호
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• pp.201-209
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• 2019

Response modification factors of school facilities for non-seismic RC moment frames with partial masonry infills in 'Manual for Seismic Performance Evaluation and Retrofit of School Facilities' published in 2018 were investigated in the preceding study. However, since previous studies are based on 2D frame analysis and limited analysis conditions, additional verification needs to be performed to further apply various conditions including orthogonal effect of seismic load. Therefore, this study is to select appropriate response modification factors of school facilities for non-seismic RC moment frames with partial masonry infills by 3D frame analysis. The results are as follows. An appropriate response modification factor for non-seismic RC moment frames with partial masonry infills is proposed as 2.5 for all cases if the period is longer than 0.6 seconds. Also if the period is less than 0.4 seconds and the ratio of shear-controlled columns is less than 30%, 2.5 is chosen too. However, if the period is less than 0.4 seconds and the ratio of shear-controlled columns is higher than 30%, the response modification factor shall be reduced to 2.0. If the period is between 0.4 and 0.6 seconds, then linearly interpolates the response correction factor.