• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.180-181
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• 2019

South Korea has long been without major earthquakes. But 317 public facilities have been damaged by Po-Hang earthquake. Among them, 103 educational facilities suffered 25.6 billion won worth of damage. This is the most damaging of public facilities. The earthquake damage was mainly centered on non-seismic retrofit educational facilities and masonry architectural wall systems installed on the outer walls of buildings. Therefore, the purpose of this study is to develop a filling material that can be applied to the non-seismic retrofit of masonry architectural wall systems installed on the outer walls of educational facilities. To achieve the objective, first, set the filling material requirements. Second, set the sequence model of experiments and prepare for the experiment. Third, after the experiment, analyze the results obtained through the experiment. Forth, the optimal filling material is selected by comparing the analyzed results with the requirements. As a results, E-S-X sample using epoxy resin were selected for the seismic retrofit of masonry architectural wall systems in educational facilities. In the future, this study can be used as a basic material for developing seismic reinforcement methods guidelines in domestic existing educational facilities.

• Earthquakes and Structures
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• 제12권1호
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• pp.1-12
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• 2017

Historical earthquakes have shown that successive seismic events may occur in regions of high seismicity. Such a sequence of earthquakes has the potential to increase the damage level of the structures, since any rehabilitation between the successive ground motions is practically impossible due to lack of time. Few studies about this issue can be found in literature, most of which focused their attention on the seismic response of SDOF systems or planar frame structures. The aim of the present study is to examine the impact of seismic sequences on the damage level of 3D multistorey R/C buildings with various structural systems. For the purposes of the above investigation a comprehensive assessment is conducted using three double-symmetric and three asymmetric in plan medium-rise R/C buildings, which are designed on the basis of the current seismic codes. The buildings are analyzed by nonlinear time response analysis using 80 bidirectional seismic sequences. In order to account for the variable orientation of the seismic motion, the two horizontal accelerograms of each earthquake record are applied along horizontal orthogonal axes forming 12 different angles with the structural axes. The assessment of the results revealed that successive ground motions can lead to significant increase of the structural damage compared to the damage caused by the corresponding single seismic events. Furthermore, the incident angle can radically alter the successive earthquake phenomenon depending on the special characteristics of the structure, the number of the sequential earthquakes, as well as the distance of the record from the fault.

• International Journal of Concrete Structures and Materials
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• 제9권3호
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• pp.345-367
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• 2015

Past earthquakes have signaled the increased collapse vulnerability of mainshock-damaged bridge piers and urgent need of repair interventions prior to subsequent cascading hazard events, such as aftershocks, triggered by the mainshock (MS). The overarching goal of this study is to quantify the collapse vulnerability of mainshock-damaged substandard RC bridge piers rehabilitated with different repair jackets (FRP, conventional thick steel and hybrid jacket) under aftershock (AS) attacks of various intensities. The efficacy of repair jackets on post-MS resilience of repaired bridges is quantified for a prototype two-span single-column bridge bent with lap-splice deficiency at column-footing interface. Extensive number of incremental dynamic time history analyses on numerical finite element bridge models with deteriorating properties under back-to-back MS-AS sequences were utilized to evaluate the efficacy of different repair jackets on the post-repair behavior of RC bridges subjected to AS attacks. Results indicate the dramatic impact of repair jacket application on post-MS resilience of damaged bridge piers-up to 45.5 % increase of structural collapse capacity-subjected to aftershocks of multiple intensities. Besides, the efficacy of repair jackets is found to be proportionate to the intensity of AS attacks. Moreover, the steel jacket exhibited to be the most vulnerable repair intervention compared to CFRP, irrespective of the seismic sequence (severe MS-severe or moderate AS) or earthquake type (near-fault or far-fault).

• Steel and Composite Structures
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• 제21권4호
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• pp.687-702
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• 2016

There are many studies in the literature conducted on the subject of ensuring earthquake safety of reinforced concrete and steel structures using steel braced frames, but no detailed study concerning individual behavior of steel braced frames under earthquake loads and strengthening of reinforced concrete structures with out-of-plane steel braced frames has been encountered. In this study, in order to evaluate behaviors of "Concentrically Steel Braced Frames" types defined in TEC-2007 under lateral loads, dimensional analysis of Concentrically Steel Braced Frames designed with different scales and dimensions was conducted, the results were controlled according to TEC-2007, and after conducting static pushover analysis, behavior and load capacity of the Concentrically Steel Braced Frames and hinges sequence of the elements constituting the Concentrically Steel Braced Frames were tested. Concentrically Steel Braced Frames that were tested analytically consist of 2 storey and one bay, and are formed as two groups with the scales 1/2 and 1/3. In the study, Concentrically Steel Braced Frames described in TEC-2007 were designed, which are 7 types in total being non-braced, X-braced, V- braced, $\wedge$- braced, $\backslash$- braced, /- braced and K- braced. Furthermore, in order to verify accuracy of the analytic studies performed, the 1/2 scaled concentrically steel X-braced frame test element made up of box profiles and 1/3 scaled reinforced concrete frame with insufficient earthquake resistance were tested individually under lateral loads, and test results were compared with the results derived from analytic studies and interpreted. Similar results were obtained from both experimental studies and pushover analyses. According to pushover analysis results, load-carrying capacity of 1/3 scaled reinforced concrete frames increased up to 7,01 times as compared to the non-braced specimen upon strengthening. Results acquired from the study revealed that reinforced concrete buildings which have inadequate seismic capacity can be strengthened quickly, easily and economically by this method without evacuating them.

• 한국산학기술학회논문지
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• 제21권9호
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• pp.662-671
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• 2020

GNSS 상시관측소 고시좌표는 측지기준점으로써의 중요성과 다양한 위성측위 응용 분야의 활용성을 고려할 때 최고의 정확도와 최신성을 갖도록 관리해야 한다. 특히, 지진 등에 따른 지각 변위는 그 크기에 해당하는 만큼 기존 성과에 편의를 유발함으로, 그 영향이 목표 정확도를 초과할 때에는 신속히 새로운 기준 좌표를 산정·제공하는 등 적절한 조치가 필요하다. 본 논문에서는 GNSS 상시관측소 데이터 자동처리 시스템과 연계 구현할 수 있는 칼만 필터에 기반 좌표 시계열의 편의검출 절차와 방법을 연구하였다. 이를 통해 필터 이노베이션과 재추정 시계열에 적용할 수 있는 통계 검정 기법을 구현한 후 과학기술용 GNSS 소프트웨어에 의해 추정한 국내 14개소 상시관측소 2010년~2011년 시계열에 적용해 그 성능과 특징을 파악하였다. 그 결과 통계검정의 오류와 신뢰성을 고려할 때 필터링 시계열에 대한 CUSUM(Cumulative Sum) 검사는 지진 등에 따른 잔류편의 그리고 이노베이션에 대한 광역검정은 특정 에포크에서 발생하는 돌출오차 검출에 효과적인 것으로 분석되었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.850-854
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• 2009

Approximate analysis for a building installed with a friction damper is revisited to get insight of its dynamic behavior. Energy balance equation is used to have a closed analytical form solution of dynamic magnification factor (DMF) for the building with combined viscous and friction damping. It is found out that DMF is dependent on friction force ratio and resonance frequency. Linear transfer function from input external force to output building displacement is obtained by simplifying DMF equation. Root mean square of building displacement is derived under earthquake-like random excitation. Finally, design of friction damper is proposed by processing target control ratio, damping ratio factor, and friction force in sequence.

• Smart Structures and Systems
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• 제19권4호
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• pp.415-429
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• 2017

This paper focuses on the impact of the wave passage effect on the long-span bridge. In order to make the wave passage effect more obvious, ground motion samples are selected from the near-fault ground motion of the 1999 Chi-Chi earthquake and an arch bridge with a 280m main span is selected as a bridge sample. The motion ground samples are divided into two groups according to the characteristics of near-fault. A sequence of fragility curves is developed. It is shown that the seismic damage is increased by the wave passage effect and the increase is more obvious in the near-fault ground motion.

• Structural Engineering and Mechanics
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• 제37권3호
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• pp.267-283
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• 2011

Although earthquakes generate random cyclic lateral loading on structures, a quasi-static cyclic loading pattern with gradually increasing amplitude has been commonly used in the laboratory tests because of its relatively low cost and simplicity compared with pseudo-dynamic and shake table tests. The number, amplitudes and sequence of cycles must be chosen appropriately as important parameters of a quasi-static cyclic loading pattern in order to account for cumulative damage matter. This paper aims to reach a new cyclic displacement pattern to be used in quasi-static tests of well-confined, flexure-dominated reinforced concrete (RC) columns. The main parameters of the study are sectional dimensions, percentage of longitudinal reinforcement, axial force intensity and earthquake types, namely, far-fault and near-fault.

• Earthquakes and Structures
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• 제14권4호
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• pp.337-347
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• 2018

This paper presents some shaking table tests conducted on a 1/4-scaled model with 5-story steel reinforced concrete (SRC) spatial frame with irregular section columns under a series of base excitations with gradually increasing acceleration peaks. The test frame was subjected to a sequence of seismic simulation tests including 10 white noise vibrations and 51 seismic simulations. Each seismic simulation was associated with a different level of seismic disaster. Dynamic characteristic, strain response, acceleration response, displacement response, base shear and hysteretic behavior were analyzed. The test results demonstrate that at the end of the loading process, the failure mechanism of SRC frame with irregular section columns is the beam-hinged failure mechanism, which satisfies the seismic code of "strong column-weak beam". With the increase of acceleration peaks, accumulated damage of the frame increases gradually, which induces that the intrinsic frequency decreases whereas the damping ratio increases, and the peaks of acceleration and displacement occur later. During the loading process, torsion deformation appears and the base shear grows fast firstly and then slowly. The hysteretic curves are symmetric and plump, which shows a good capacity of energy dissipation. In summary, SRC frame with irregular section columns can satisfy the seismic requirements of "no collapse under seldom earthquake", which indicates that this structural system is suitable for the construction in the high seismic intensity zone.

• 한국지진공학회논문집
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• 제11권6호
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• pp.23-32
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• 2007

본 연구에서는 PT 플랫 플레이트 골조의 내진성능을 평가하기 위하여 비선형 거동을 예측할 수 있는 해석모델을 개발하였다. 특히 본 연구에서 개발한 해석 모델은PT 플랫 플레이트 슬래브-기둥 접합부에서 기둥을 관통하는 철근이 있는 경우와 없는 경우의 접합부 거동을 정확하게 예측할 수 있도록 개발하였다. 또한 본 연구에서 개발한 접합부 해석 모델은PT 플랫 플레이트 슬래브-기둥 접합부에서 뚫림 전단 파괴가 발생하는 때를 정확하게 예측하도록 하였다. 개발한 해석 모델의 타당성을 검증하기 위하여PT 플랫 플레이트 슬래브-기둥 접합부 실험결과와 해석 결과를 비교하였다. 또한 2층 PT 플랫 플레이트 골조의 진동대 실험결과와 해석결과를 비교하였다. 본 연구에서는 기둥을 관통하는 철근이 있는 접합부와 없는 접합부를 갖는 2층 PT 플랫 플레이트 골조를 세 가지의 크기로 조정한El Centro 지진에 대하여 비선형 동적 해석을 수행하였다. 지진의 크기가 커지면 하부 철근이 없는 골조의 요구 변위와 잔류 변형이 하부 철근이 있는 골조에 비하여 더욱 커지는 것으로 나타났다.