• 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.

• Earthquakes and Structures
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• 제19권3호
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• pp.157-174
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• 2020

The in-situ pushover test differs from the shake-table test because it is performed outdoors and thus its size is not restricted by space, which allows us to test a full-size building. However, to build a new full-size building for the test is not economical, consequently scholars around the world usually make scale structures or full-scale component units to be tested in the laboratory. However, if in-situ pushover tests can be performed on full-size structures, then the seismic behaviors of buildings during earthquakes can be grasped. In view of this, this study conducts two in-situ pushover tests of reinforced concrete (RC) buildings. One is a masonry-infilled RC building with openings (the openings ratio of masonry infill wall is between 24% and 51%) and the other is an RC building without masonry infill. These two in-situ pushover tests adopt obsolescent RC buildings, which will be demolished, to conduct experiment and successfully obtain seismic capacity curves of the buildings. The test results are available for the development or verification of a seismic evaluation model. This paper uses ASCE 41-17 as the main evaluation model and is accompanied by a simplified pushover analysis, which can predict the seismic capacity curves of low-rise buildings in Taiwan. The predicted maximum base shear values for masonry-infilled RC buildings with openings and for RC buildings without masonry infill are, respectively, 69.69% and 87.33% of the test values. The predicted initial stiffness values are 41.04% and 100.49% of the test values, respectively. It can be seen that the ASCE 41-17 evaluation model is reasonable for the RC building without masonry infill walls. In contrast, the analysis result for the masonry infilled RC building with openings is more conservative than the test value because the ASCE 41-17 evaluation model is limited to masonry infill walls with an openings ratio not exceeding 40%. This study suggests using ASCE 41-17's unreinforced masonry wall evaluation model to simulate a masonry infill wall with an openings ratio greater than 40%. After correction, the predicted maximum base shear values of the masonry infilled RC building with openings is 82.60% of the test values and the predicted initial stiffness value is 67.13% of the test value. Therefore, the proposed method in this study can predict the seismic behavior of a masonry infilled RC frame with large openings.

• Structural Engineering and Mechanics
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• 제47권3호
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• pp.401-419
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• 2013

In this study, the efficiency of adaptive neuro-fuzzy inference system (ANFIS) and genetic expression programming (GEP) in predicting the effects of infill walls on base reactions and roof drift of reinforced concrete frames were investigated. Current standards generally consider weight and fundamental period of structures in predicting base reactions and roof drift of structures by neglecting numbers of floors, bays, shear walls and infilled bays. Number of stories, number of bays in x and y directions, ratio of shear wall areas to the floor area, ratio of bays with infilled walls to total number bays and existence of open story were selected as parameters in GEP and ANFIS modeling. GEP and ANFIS have been widely used as alternative approaches to model complex systems. The effects of these parameters on base reactions and roof drift of RC frames were studied using 3D finite element method on 216 building models. Results obtained from 3D FEM models were used to in training and testing ANFIS and GEP models. In ANFIS and GEP models, number of floors, number of bays, ratio of shear walls and ratio of infilled bays were selected as input parameters, and base reactions and roof drifts were selected as output parameters. Results showed that the ANFIS and GEP models are capable of accurately predicting the base reactions and roof drifts of RC frames used in the training and testing phase of the study. The GEP model results better prediction compared to ANFIS model.

• Structural Engineering and Mechanics
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• 제44권1호
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• pp.85-107
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• 2012

The building frame and its foundation along with the soil on which it rests, together constitute a complete structural system. In the conventional analysis, a structure is analysed as an independent frame assuming unyielding supports and the interactive response of soil-foundation is disregarded. This kind of analysis does not provide realistic behaviour and sometimes may cause failure of the structure. Also, the conventional analysis considers infill wall as non-structural elements and ignores its interaction with the bounding frame. In fact, the infill wall provides lateral stiffness and thus plays vital role in resisting the seismic forces. Thus, it is essential to consider its effect especially in case of high rise buildings. In the present research work the building frame, infill wall, isolated column footings (open foundation) and soil mass are considered to act as a single integral compatible structural unit to predict the nonlinear interaction behaviour of the composite system under seismic forces. The coupled isoparametric finite-infinite elements have been used for modelling of the interaction system. The material of the frame, infill and column footings has been assumed to follow perfectly linear elastic relationship whereas the well known hyperbolic soil model is used to account for the nonlinearity of the soil mass.

• KCI Concrete Journal
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• 제11권3호
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• pp.165-174
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• 1999

The objective of the research stated herein is to observe the elastic and inelastic behaviors and ultimate capacity of 1:5 scale 3-story reinforced concrete frame. Pushover tests were performed to 1:5 scale 3-story reinforced concrete frames with and without infilled masonry. To simulate the earthquake effect, the lateral force distribution was maintained by an inverted triang1e by using the whiffle tree. From the test results, the relation ships between the total lateral load and the roof drift, the distribution of column shears, the relation between story shear and story drift, and the angular rotations at the critical portions of structures were obtained. The effects of infilled masonry were investigated with regards to the stiffness, strength, and ductility of structures. Final collapse modes of structures with and without infilled masonry were compared.

• 한국구조물진단유지관리공학회 논문집
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• 제21권3호
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• pp.121-129
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• 2017

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

• Earthquakes and Structures
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• 제9권2호
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• pp.281-303
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• 2015

The effects of infill panels on the response of r.c. frames subjected to seismic action are widely recognized. Numerous experimental investigations were effected and several analytical models were developed on this subject. This work, which is part of a larger project dealing with specific materials and structures commonly used in Italy, discusses experimental tests on masonry and samples of bare and infilled portals. The experimental activity includes tests on elemental materials, and 12 wall samples. Finally, three one-bay one-story reinforced concrete frames, designed according to the outdated Italian technical code D.M. 1996 without seismic details, were tested (bare and infilled) under constant vertical and cyclic lateral load. The first cracks observed on the framed walls occurred at a drift of about 0.3%, reaching its maximum capacity at a drift of 0.5% while retaining its capacity up to a drift of 0.6%. Infill contributed to both the stiffness and strength of the bare reinforced concrete frame at small drifts thus improving overall system behavior. In addition to the experimental activities, previously mentioned, the recalibration of a model proposed by Comberscue (1996) was evaluated. The accuracy of an OpenSees non linear fiber based model of the prototype tested, including a strut element was verified through a comparison with the final experimental results. This work has been partially supported by research grant DPC-ReLUIS 2014.

• 한국강구조학회 논문집
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• 제21권2호
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• pp.115-125
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• 2009

철근콘크리트 골조에 얇은 강판채움벽을 접합한 합성벽의 내진 성능을 연구하기 위한 실험을 실시하였다. 실험체로서 얇은 채움강판을 사용한 3층 합성벽을 사용하였다. 주요 실험 변수는 기둥의 철근비와 채움벽의 개구부이다. 비교를 위하여 철근콘크리트 채움벽과 철근콘크리트 골조에 대한 실험을 실시하였다. 강판채움벽을 갖는 합성벽 실험체는 철근콘크리트 채움벽과 동일한 하중재하능력을 나타내면서도 변형능력이 크게 향상되었다. 또한 철골 골조를 사용한 강판벽 시스템과 마찬가지로 우수한 강도, 큰 변형능력 및 에너지소산 능력을 나타냈다. RC 골조에 대한 강판채움벽의 보강효과로 기둥-보 접합부의 전단균열과 손상을 방지할 수 있었다. 스트립 모델을 사용한 해석 연구를 통하여 합성벽 실험체의 강성 및 강도를 예측하였으며, 해석결과를 실험결과와 비교했다.

• 한국구조물진단유지관리공학회 논문집
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• 제11권2호
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• pp.109-116
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• 2007

본 논문의 목적은 경량기포모르터를 충전한 스틸스터드와 복합스터드 내력벽체의 내화성능을 KS규준에 따라 평가하는데 있다. 주거용과 상업용 건물의 최소 내화 요구시간은 2시간이다. 시험 결과로부터 스틸 스터드와 복합스터드에 경량기포 모르터를 충전한 두 시험체 모두 2시간 내화 성능을 만족하는 것으로 나타났다. 또한 복합스터드 패널 시험체의 경우 내화 성능면에서 스틸 스터드 패널 시험체 보다 우수하다는 것을 정량적 평가하였다.

• 복합신소재구조학회 논문집
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• 제6권2호
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• pp.52-62
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• 2015

This study aims at developing a new seismic resistant method by using precast concrete wall panels for existing low-rise, reinforced concrete beam-column buildings such as school buildings. Three quasi-static hysteresis loading tests were performed on one unreinforced beam-column specimen and two reinforced specimens with U-type precast wall panels. Top shear connection of the PC panel was required to show the composite strength of RC column and PC wall panel. However, the strength of the connection did not influence directly on the ultimate loading capacities of the specimens in the positive loading because the loaded RC column push the side of PC wall panel and it moved horizontally before the shear connector receive the concentrated shear force in the positive loading process. Under the positive loading sequence(push loading), the reinforced concrete column and PC panel showed flexural strength which is larger than 97% of the composite section because of the rigid binding at the top of precast panel. Similar load-deformation relationship and ultimated horizontal load capacities were shown in the test of PR1-LA and PR1-LP specimens because they have same section dimension and detail at the flexural critical section. An average of 4.7 times increase in the positive maximum loading(average 967kN) and 2.7 times increase in the negative maximum loading(average 592.5kN) had resulted from the test of seismic resistant specimens with anchored and welded steel plate connections than that of unreinforced beam-column specimen. The maximum drift ratios were also shown between 1.0% and 1.4%.