This study investigated the seismic performance of reinforced concrete (RC) wall-slab frames with masonry infills. Four RC wall-slab frames with or without masonry infill were tested under cyclic loading. The RC frames were composed of in-plane and out-of-plane walls and top and bottom slabs. For masonry infill walls, cement bricks were stacked applying mortar paste only at the bed joints, and, at the top, a gap of 50 mm was intentionally left between the masonry wall and top RC slab. Both sides of the masonry walls were finished by applying ordinary or fiber-reinforced mortars. The tests showed that despite the gap on top of the masonry walls, the strength and stiffness of the infilled frames were significantly increased and were different depending on the direction of loading and the finishing mortars. During repeated loading, the masonry walls underwent horizontal and diagonal cracking and corner crushing/spalling, showing a rocking mode inside the RC wall-slab frame. Interestingly, this rocking mode delayed loss of strength, and as a result, the ductility of the infilled frames increased to the same level as the bare frame. The interaction of masonry infill and adjacent RC walls, depending on the direction of loading, was further investigated based on test observations.

최근 경주지진과 포항지진 피해사례에서 보이듯 조적벽체 구조물의 붕괴 위험이 사회적으로 큰 주목을 받고 있다. 본 연구는 수평하중에 대한 강성이 구조적으로 취약한 조적벽체 구조물에 대하여 개선된 보강재 설계 및 이를 통한 구조성능 평가를 수행하였다. 선행기술에서 제시한 FRP Plate 보강재의 경우 외부 부착 시 계면 부착파괴에 의한 보강성능 저감이 발생하는 것을 고려하여 본 연구에서는 사전제작 매립형 T-Joint BFRP 보강재를 개발하였으며, 이를 혼합 에폭시계 연성페인트와 혼합 하여 보강 구조물의 마감효과 및 에너지흡수성능을 개선하는 방법으로 제안하였다. 실험 결과, 보강 시험체의 강성은 약 1.37배, 에너지소산능력은 약 2.59배 개선됨을 확인하였다.

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).

The purpose of this study is to make a generalized analytical based on the proposed experiments on reinforced concrete(RC) partially infilled frames by U-type precast concrete(PC) wall panels with openings. RC frame and PC wall panels were connected with different strengths. Therefore, we developed modified strut-tie model(STM) with two seismic retrofitting specimens and conducted a nonlinear analysis by using a computer analysis program. Based on the test results, truss member of modified STM was designed, applying the strut-tie model theory of ACI 318M-11 Appendix- A. As a result, the modified STM analysis results were very similar to the experimental results. As a result of the load-displacement curve comparison, the failure load were similar within 5∼17% of error range. In particular, the experimental results and the results of modified STM analysis show that the failure behavior almost matched.

Cyclic loading test was performed on the partially infilled reinforced concrete(RC) frames by L-type precast concrete(PC) wall panels with the connections of two different strength. Based on the results of experimental test, the nonlinear analysis was practiced with modified strut-tie model(STM) method by using a computer program. Truss member of modified STM was designed, applying the strut-tie model theory of ACI 318M-11 Appendix-A. Modified STM was designed with two ways according to the test result. PC wall panel and RC frame were assumed to composite when push loading applied. The PC and RC structures were also assumed to behave non-composite and those two structures connected with link(top connector) when pull loading applied. The connection was designed by using elastic link of program. The results of analytical modified STM process generally conform to the experimental results. The failure load and the failure mode of the specimens could be predicted using modified STM. The ratio of failure load measured in specimens to analytical values were between 0.83∼1.16. The member or connection which was failed in experiment yield in the results of modified STM. The failure mode perfectly matched.

When reinforcing an existing reinforced concrete beam-column building with a precast concrete panel, special connection between the PC member and the RC member is required to solve the time dependent deformation of the RC member and to receive the large shear forces. The aim of this study is to obtain the shear strength of upper connection between the existing RC beam-column and infilled PC wall panels in experimentally and theoretically. Thus, the static shear loading tests were conducted on the 6 specimens with the plate connection. Shear failure was resulted from the weakest portion of interior PC panel, exterior RC, and the connection, when the PC portion which located at the center of specimen was pulled upward from the bottom. T he experimental result was compared with analytical result from ACI 318M-14 Chapter 17 for the shear strength of post-installed anchor and PCI Handbook 7th edition 6.8 Structural Steel Corbel (PCI Design Handbook 7th edition, 2010) for the strength of cast-in H-beam. The analytical and experimental results show final failure at the same location. The failure loading of experiment showed larger than average 6% to that of the analysis.

This report offers an economically reasonable seismic reinforcement to non-seismic mid/low reinforced concrete structures. Installed a slit in between the reinforced concrete frame and masonry infilled wall then inserted twist bar to prevent inversion and attached to the lower/upper beam. Confirmed the seismic reinforcement effect through static loading test. Total of 4 specimens were produced for the test, a masonry infilled wall without seismic reinforcement and with seismic slit or twist bar applied. As a result, applying the seismic slit and twisted bar was economically reasonable and seismic reinforcement effect was confirmed by showing stable failure, increase of maximum strength and yield displacement, increase of accumulated energy dissipation.

본 논문에서는 범용유한요소해석 프로그램인 ABAQUS를 사용하여 국내에서 사용되는 콘크리트벽돌을 조적채움벽으로 가진 철근콘크리트 골조를 대상으로 유한요소해석을 실시하였다. 해석대상은 순수골조, 채움벽의 두께가 0.5B인 골조, 두께가 1.0B인 골조의 3종류이다. 철근콘크리트 골조 및 채움벽의 재료특성은 재료시험 결과로부터 구하였으나 두께가 1.0B인 채움벽의 경우 벽돌의 쌓기방법의 차이에 의해 0.5B 두께의 실험체보다 4배 정도 증가된 인장강도를 사용하였다. 유한요소해석결과는 실험을 통해 구한 하중-변위관계 및 변위각에 따른 균열양상을 상당히 정확하게 예측하였다. 유한요소해석 결과의 분석을 통해 조적채움벽과 골조사이의 접촉응력 및 골조의 전단력과 휨모멘트를 산정하였다.

본 연구에서는 저층 조적채움벽 철근콘크리트 골조 구조물의 내진보강 전과 후에 대하여 강제 진동 실험과 상시 진동 계측을 수행하였으며 시스템 식별과정을 통하여 구조물의 동특성을 구하고 해당 구조물과 유사한 동특성을 보이는 해석 모델을 만들었다. 시스템 식별 결과 댐퍼가 설치된 x방향의 감쇠비가 증가되었으며, 해석 모델과 비교한 결과 추가 설치된 부재들(전단벽과 댐퍼)의 유효 강성은 부재의 총단면 강성의 50%만이 발현되어 해당 부재들이 기존의 구조물이나 부재와 완전히 일체화되지는 않음을 알 수 있었다. 또한, 추가 설치된 기초의 y방향 구속조건을 핀으로 하여야 동특성을 일치시킬 수 있었는데, 이는 새로운 기초가 설치되며 해당 지질의 특성이 변화되었기 때문으로 보인다.

In this study, material tests were performed on the masonry specimens constructed with bricks and mortar used in Korea. The specimens included two types of thickness(0.5B and 1.0B) and physical conditions (good and poor). It was shown that 1.0B specimens have 3.2~1.8 times larger shear strength than 0.5B specimens and shear strength of specimens in poor condition was 66%~38% of those in good condition. Average shear stress of masonry-infills was calculated from previous experimental studies, and relationships with failure mode, material strength of masonry, aspect ratio, and frame-to-infill strength ratio were investigated. In addition, the effects of masonry strength on the seismic performance of a masonry-infilled frame was studied using a simple example building. It can be seen that the obtained average shear stress were considerably higher than the default masonry shear strength recommended by the ASCE 41, and low values the strength of masonry does not guarantee conservative evaluation results due to the early shear failure of frame members.

Masonry-infilled walls have been used in reinforced concrete(RC) frame structures as interior and exterior partition walls. Since these walls are considered as nonstructural elements, they were only considered as additional mass. However, infill walls tend to interact with the structure’s overall strength, rigidity, and energy dissipation. Infill walls have been analyzed by finite element method or transposed as equivalent strut model. The equivalent strut model is a typical method to evaluate masonry-infilled structure to avoid the burden of complex finite element model. This study compares different strut models to identify their properties and applicability with regard to the characteristics of the structure and various material models.

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.

본 연구에서는 학교건물에서 나타나는 전형적인 조적조 채움벽 골조의 내진성능을 등가 스트럿 모델을 통해 평가하였다. 순수골조모델, 중심스트럿모델 및 편심스트럿모델의 세 가지 모형화 방법을 채택하였고, 문헌상으로 얻을 수 있는 범위의 스트럿 강성과강도를 적용하여 거동특성의 차이를 분석하였다. 역량스펙트럼에 의해 산정된 성능점에서의 변위 및 손상정도에 큰 차이가 나타났으며,채움벽은 순수골조모델과 비교할 때 중심스트럿모델에서는 유리하게, 편심스트럿모델에서는 불리하게 작용하는 것으로 나타났다. 최종극한변위에서의 거동 또한 모형화 방법 및 재료 속성에 따라서 최대강도, 층간변위, 파괴된 부재 수 및 위치 등에 큰 차이가 나타났다.

본 논문에서는 국내 비내진상세 조적채움벽 RC 골조의 동적거동 및 손상모드를 파악하기 위하여 실규모 크기의 비내진상세 RC 골 조와 조적채움벽 RC 골조를 대상으로 진동대 실험을 실시하여 응답 및 거동 특성을 비교 평가하였다. 진동대 실험 결과, 순수 RC 골조는 기둥 상하부 휨균열 및 접합부 전단균열이 심화되어 최종 파괴되었다. 조적채움벽 RC 골조의 경우 골조의 손상은 비교적 작았으며 조적벽체의 중앙 부의 슬라이딩 균열 및 대각 전단 균열 손상이 크게 발생하였다. 조적채움벽 RC 골조는 순수 RC 골조에 비하여 초기상태의 공진주기가 짧아졌 으며 최종 가진시에서 최대변위응답은 약 62% 감소하였다. 본 연구에서 적용한 조적채움벽은 비내진 상세를 가지는 RC 골조의 강성을 약 1.6 배, 최대 강도를 약 2.2배 증가시키는 데 기여하는 것으로 분석되었다.

When reinforcing an existing reinforced concrete beam-column building with a precast concrete panel, special connection between the PC member and the RC member is required to solve the time dependent deformation of the RC member and to receive the large shear forces. The aim of this study is to obtain the shear strength of upper connection between the existing RC beam-column and infilled PC wall panels in experimentally and theoretically. Thus, the static shear loading tests were conducted on the 6 specimens with the plate connection. Shear failure was resulted from the weakest portion of interior PC panel, exterior RC, and the connection, when the PC portion which located at the center of specimen was pulled upward from the bottom. The experimental result was compared with analytical result from ACI 318M-14 Chapter 17 for the shear strength of post-installed anchor and PCI Handbook 7th edition 6.8 Structural Steel Corbel (PCI Design Handbook 7th edition, 2010) for the strength of cast-in H-beam. The analytical and experimental results show final failure at the same location. The failure loading of experiment showed larger than average 6% to that of the analysis.

When reinforcing an existing reinforced concrete beam-column building with a precast concrete panel, special connection between the PC member and the RC member is required to solve the time dependent deformation of the RC member and to receive the large shear forces. The aim of this study is to obtain the shear strength of upper connection between the existing RC beam-column and infilled PC wall panels in experimentally and theoretically. Thus, the static shear loading tests were conducted on the 6 specimens with the plate connection. Shear failure was resulted from the weakest portion of interior PC panel, exterior RC, and the connection, when the PC portion which located at the center of specimen was pulled upward from the bottom. The experimental result was compared with analytical result from ACI 318M-14 Chapter 17 for the shear strength of post-installed anchor and PCI Handbook 7th edition 6.8 Structural Steel Corbel (PCI Design Handbook 7th edition, 2010) for the strength of cast-in H-beam. The analytical and experimental results show final failure at the same location. The failure loading of experiment showed larger than average 6% to that of the analysis.

This study carried out a series of seismic tests to elucidate the difference of movements between two buildings with or without masonry infilled wall in reinforced concrete frames which have no quake proof plan. Both of the experimental buildings showed irreversible deformity at low drift ratio of 0.6%. The strength and stiffness of the building with masonry infilled wall were higher than those of the building without masonry infilled wall, while the ductility of the former being lower than that of the latter. Thus it led to more brittle tendency of the former.

일반적으로 조적조는 시공이 용이하고 경제적인 구조로서 국내뿐만 아니라 해외에서도 가장 오래되고 광범위하게 사용되는 구조이다. 조적벽을 RC 골조에 장막벽으로 사용하는 채움벽 형태의 구조는 시공이 용이하고 경제적이기 때문에 저층 주거용 건물, 학교건물 등에 많이 적용되고 있으나, 설계시에는 비구조부재로 취급되어 채움벽의 효과를 반영하지 않고 있다. 본 연구에서는 기존의 사각형 조적개체의 횡력에 대한 취약성을 개선하기 위해 개발된 육각형 블록을 RC 골조 채움벽에 적용한 채움벽 골조에 대한 구조실험을 수행하여 육각형블록 조적채움벽의 효과를 평가하고자 하였다.