• 한국구조물진단유지관리공학회 논문집
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• 제27권6호
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• pp.182-192
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• 2023

본 연구에서는 동적 횡하중을 받는 조적 담장의 내진성능 향상을 위한 ECC(Engineered Cementitious Composite) 자켓의 효과를 실험적으로 검증하였다. 첫째로, 임팩트 해머 시험을 통해 비보강과 ECC로 보강된 조적 담장의 고유진동수와 모드 감쇠비, 변형 형상을 식별하여, 940mm의 비보강 조적담장과 970mm의 ECC 보강 담장이 각각 6.4, 35.3Hz의 고유진동수와 7.0, 5.3%의 감쇠비를 가지는 것을 확인하였다. 둘째로, 진동대를 사용하여 면외방향에 대한 지진파 실험을 수행하였고, El Centro(1940) 지진파를 25%부터 300%까지 스케일링하여 적용하였다. 비보강 조적담장의 경우, 50% 지진하중에서 벽돌과 줄눈 경계에 휨균열이 발생하였고, 다시 30%로 스케일링된 지반운동에서 면외방향으로 전도파괴되었다. 반면에 ECC로 보강된 조적담장은 300%의 지진하중에서도 균열이나 손상 없이 강건한 성능을 유지하였다. 마지막으로, 25~300%의 지반운동에 의한 비보강과 ECC 보강 조적담장의 밑면전단력과 설계기준에 따른 밑면전단력을 비교 및 평가하였다. 그 결과, 재현주기 1,000년의 지진에 대해 비보강 조적담장이 붕괴될 위험이 있는 데 반해, ECC 보강 담장은 4,800년 주기의 지진에도 안전한 것으로 추정되었다.

• Earthquakes and Structures
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• 제9권4호
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• pp.789-830
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• 2015

The recent re-assessment of the seismic hazard in Europe led for many regions of low to moderate seismicity to an increase in the seismic demand. As a consequence, several modern unreinforced masonry (URM) buildings, constructed with reinforced concrete (RC) slabs that provide an efficient rigid diaphragm action, no longer satisfy the seismic design check and have been retrofitted by adding or replacing URM walls with RC walls. Of late, also several new construction projects have been conceived directly as buildings with both RC and URM walls. Despite the widespread use of such construction technique, very little is known about the seismic behaviour of mixed RC-URM wall structures and codes do not provide adequate support to designers. The aim of the paper is therefore to propose a displacement-based design methodology for the design of mixed RC-URM edifices and the retrofit of URM buildings by replacing or adding selected URM walls with RC ones. The article describes also two tools developed for estimating important quantities relevant for the displacement-based design of structures with both RC and URM walls. The tools are (i) a mechanical model based on the shear-flexure interaction between URM and RC walls and (ii) an elastic model for estimating the contribution of the RC slabs to the overturning moment capacity of the system. In the last part of the article the proposed design method is verified through nonlinear dynamic analyses of several case studies. These results show that the proposed design approach has the ability of controlling the displacement profile of the designed structures, avoiding concentration of deformations in one single storey, a typical feature of URM wall structures.

• 한국구조물진단유지관리공학회 논문집
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• 제18권4호
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• pp.33-40
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• 2014

본 연구는 비보강 조적조 건축물의 정밀한 내진성능 평가를 위한 기초 연구로써, 조적벽체의 형상비 및 개구부 유무에 따른 파괴모드를 고려하여 기존의 전단강도 제안식을 비교 평가하고, 이를 반영한 복원력 특성모델을 제안하였다. 개구부가 없는 조적벽체의 전단강도는 국내 기존 연구에서 제안된 강체회전 및 양단부 압축파괴 강도와 FEMA의 미끄러짐 전단강도 중 작은 값을, 개구부가 있는 벽체의 경우 Pier 벽체만을 고려하여 강도를 예측하는 것이 적절한 것으로 평가되었다. 또한 파괴모드를 고려하여 휨 및 전단거동의 복원력 특성 모델을 제시하였으며, 이를 적용하여 비선형 반복가력 해석을 수행한 결과, 강도 및 이력 거동 면에서 실험과 유사한 결과를 얻을 수 있었다.

• 한국구조물진단유지관리공학회 논문집
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• 제15권4호
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• pp.116-124
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• 2011

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.

• Earthquakes and Structures
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• 제10권4호
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• pp.811-828
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• 2016

This study aims to present nonlinear time history analysis results of double leaf cavity wall (DLCW) reinforced concrete structure exposed to shake table tests. Simulation of the model was done by a Finite Element (FE) program. Shake table experiment was performed at the National Civil Engineering Laboratory in Lisbon, Portugal. The results of the experiment were compared with numeric DLCW model and numeric model of reinforced concrete structure with unreinforced masonry wall (URM). Both DLCW and URM models have two bays and two stories. Dimensions of the tested structure and finite element models are 1:1.5 scaled according to Cauchy Froude similitude law. The URM model has no experimental results but the purpose is to compare their performance level with the DLCW model. Results of the analysis were compared with experimental response and were evaluated according to ASCE/SEI 41-06 code.

• Earthquakes and Structures
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• 제5권5호
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• pp.571-588
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• 2013

Many of the current buildings in Algeria were built in the past without any consideration to the requirements of the seismic code. Among these buildings, there are a large number of individual houses built in the 1980's by their owners. They are Reinforced Concrete (RC) frame structures with unreinforced hollow masonry infill walls. This buildings type experienced major damage in the 2003 (Algeria) earthquake, generated by deficiencies in the structural system. In the present study, special attention is placed upon examining the vulnerability of RC frame houses. Their situation and their general features are investigated. Observing their seismic behavior, structural deficiencies are identified. The seismic vulnerability of this type of buildings depends on several factors, such as; structural system, plan and vertical configuration, materials and workmanship. The results of the vulnerability assessment of a group of RC frame houses are presented. Using a method based on the European Macroseismic Scale EMS-98 definitions, presented in previous studies, distribution of damage is obtained.

• Earthquakes and Structures
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• 제14권5호
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• pp.449-458
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• 2018

Earthquakes have shown the vulnerability of unreinforced masonry (URM) structures. The aim of this research is to study a technique for in-plane seismic retrofitting of URM walls in which both diagonal and vertical steel strips are added to a single side of a URM wall. Specimens have been tested under quasi-static cyclic lateral load in combination with constant vertical load. The tests show that vertical and diagonal strips cause a significant increase in seismic capacity in terms of both strength (about 200%) and displacement at maximum (about 20%). Furthermore, this technique caused the failure modes of URM walls were influenced.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.312-319
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• 2001

The purpose of this study is to evaluate the strength of piers subjected to earthquake ground motion. In particular, the piers of an unreinforced masonry wall under in-plane seismic loading are considered with emphasis. For this purpose, several pier strength equations in seismic rehailitation provisions such as UCBC, FEMA 178, FEMA 273, and FEMA 306 are compared. This strength equations in different provision are applied for calculating the strength of a pier in building. According to the results of this study, it is shown that the assessment procedure based on FEMA 178 overestimated pier strengths comparing to other provisions when all piers are in Rocking-controlled mode.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.46-49
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• 2006

In general, the shear behavior mode of URM wall expresses four types of modes such as rocking failure, sliding shear failure, toe crushing failure, and diagonal tension failure. From the comparison of each equation according to the shear behavior modes, the failure modes based on the aspect ratio and vertical axial stress can be expected. The objectives of this study is to find out the shear behavior of URM wall with different aspect ratio. The test results show that the aspect ratio is understood as an important variable.

• Earthquakes and Structures
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• 제13권3호
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• pp.309-322
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• 2017

In this paper, a simplified evaluation method of the skeleton curve for reinforced concrete (RC) frame with unreinforced masonry (URM) infill is proposed in a practical form, based on the previous studies. The backbone curve for RC boundary frame was modeled by a tri-linear envelope with cracking and yielding points. On the other hand, that of URM infill was modeled by representative characteristic points of cracking, maximum, and residual strength; also, the interaction effect between RC boundary frame and the infill was taken into account. The overall force-displacement envelopes by the sum of RC boundary frame and URM infill, where the backbone curves of the infill from other studies were also considered, were then compared with the previous experimental results. The simplified estimation results from this study were found to almost approximate the overall experimental results with conservative evaluations, and they showed much better agreement than the cases employing the infill envelopes from other studies.