• Title/Summary/Keyword: 연성벽체

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Ductility Confinement of RC Rectangular Shear Wall (장방형 철근 콘크리트 전단벽의 연성 보강)

  • 강수민;박홍근
    • Journal of the Korea Concrete Institute
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    • v.14 no.4
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    • pp.530-539
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    • 2002
  • In designing the boundary confinement of shear walls, the current design provisions and recommendations are empirical and prescriptive; they specify a certain confinement length and details, regardless of the actual requirement of ductility Therefore, they are inappropriate to the performance based-design. The purpose of the present study is to develop a ductility design method that Is applicable to the performance based-design of shear wall. For the purpose, experimental studies were performed to investigate variations in the ductility of shear walls with the length of the boundary confinement. Five specimens modeling the compressive zone of cross sections with different confinement area were tested against eccentric vertical load. Through the experimental studies, strength, ductility, and failure mode of the compression zone were investigated. In addition, nonlinear numerical analyses for the overall cross-sections of shear wall were performed to investigate variations of the stress and strain profiles with the length of compression zone. On the basis of the experimental and numerical studies, a ductility design method for shear wall was developed. By using the proposed design method, for a given ductility demand, the area of lateral confinement and corresponding reinforcement ratio can be precisely determined so that the ductile behavior and economical design are assured.

Evaluation of Ground Deformation during Excavation of Vertical Shaft through Centrifuge Model Test (원심모형실험을 통한 원형 수직구 굴착 중 발생하는 지반 변형 평가)

  • Kim, Joonyoung
    • Journal of the Korean Geotechnical Society
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    • v.38 no.1
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    • pp.35-45
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    • 2022
  • When constructing a cylindrical vertical shaft through the open-cut method, the walls are generally designed to be temporary flexible walls that allow a certain level of displacement. The earth pressure applied to the flexible walls acts as an external force and its accurate estimation is essential for reasonable and economical structure design. The earth pressure applied to the flexible wall is closely interrelated to the plastic deformation of the surrounding ground. This study simulated a stepwise excavation for constructing a cylindrical vertical shaft through a centrifugal model test and evaluated the continuous deformation behaviors of the surrounding ground through digital image analysis.

Membrane Diffusion through Flexible-Wall Permeameter for Soil Flushing Tests (연성벽체 투수기를 이용한 흙세척 실험시 벽막을 통한 확산량 산정)

  • Junboum Park;Jee-Sang Kim
    • Journal of Korea Soil Environment Society
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    • v.2 no.2
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    • pp.95-103
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    • 1997
  • Solvent extraction using aqueous solutions is presumed as one of the most effective methods applicable to in situ conditions without excavation of contaminated soils. Laboratory permeameter soil flushing test is performed to describe the process of solvent extraction of contaminants absorbed on soil particles. When the permeameter tests conducted, diffusion of contaminants through the permeameter flexible-wall was considered for adjusting the remediation percentage. Input and output balance for concentration was well matched in the permeameter tests. Nitrobenzene diffused so excessively (approximately 75%) that it was not suitable for the permeameter desorption tests. No biodegradation was detected in the soil samples.

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Evaluation of the Sequential Behavior of Tieback Wall in Sand by Small Scale Model Tests

  • Seo, Dong-Hee;Chang, Buhm-Soo;Jeong, Sang-Seom;Kim, Soo-Il
    • Journal of the Korean Geotechnical Society
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    • v.15 no.3
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    • pp.113-129
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    • 1999
  • In this study, a total of 12 types of sequential model tests were conducted at the laboratory for small scale anchored walls. The sequential behavior for flexible wall embedded in sand was investigated by varying degrees of relative density of Joomoonjin sand and flexibility number of model wall. The model tests were carried out in a 1000mm width, 1500mm length, and 1000mm high steel box. Load cells, pressure cells, displacement transducer and dial gauges were used to measure the anchor forces, lateral wall deflections, lateral earth pressures and vertical displacements of ground surface, respectively. Limited model tests were performed to examine the parameters for soil-wall interaction model and the formulation of analytical method was revised in order to predict the behavior of anchored wall in sand. Based on the model tests and proposed analytical method, model simulations were performed and the predictions by the present approach were compared with measurements by the model tests and predictions by other commercial programs. It is shown that the prediction by the present approach simulates qualitatively well the general trend observed for model test.

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Evaluation of Seismic Strengthening Approach at the Boundary Elements of RC Walls using Prestressed Wire Rope Units (프리스트레스트 와이어로프를 사용한 RC 벽체의 단부 경계요소 내진보강 평가)

  • Kwon, Hyuck-Jin;Yang, Keun-Hyeok;Byun, Hang-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.1
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    • pp.56-63
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    • 2018
  • The present study examined the reversal cyclic flexural behavior of walls with jacket section approach for seismic strengthening through forming the boundary elements at both ends of the wall. The prestressed wire ropes were used for the lateral reinforcement to confine the boundary element of the wall. The main parameter investigated was the height of the jacket section for strengthening. The limit height of the strengthening jacket section was determined by comparing the moment distributions between the existing and strengthened walls. Test results showed that the examined jacket section approach was significantly effective in enhancing the flexural resistance of walls, indicating 46% higher stiffness at peak strength and 210% greater work damage indicator, compared with the flexural performance of the unstrengthened wall. The ductility of the strengthened walls was insignificantly affected by the height of the jacket section when the height is greater than twice the wall length. The flexural capacity of the strengthened walls was 22% higher than the predictions obtained using the equivalent stress block specified in ACI 318-14.

Strengthening of shear resistance of masonry walls (조적벽체의 전단강도 향상 방안에 관한 연구)

  • Kang, Sung-Hun;Hong, Sung-Gul
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.193-196
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    • 2008
  • This paper presents an experimental study to investigate enhanced performance of the masonry walls strengthened in shear and ductility using honeycomb steel mesh. The performance of masonry walls strengthened with steel mesh will compare with unreinforced masonry walls to show the performance of reinforced masonry walls. According to the experiment, it is expected that this system is effective to enhance the shear strength and ductility of the masonry walls.

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Case Study of the Characteristic of Ground Deformation and the Strut Axial Force Change in Long Span Deep Excavation (장지간 깊은 굴착에서 지반변형 및 버팀보 축력변화 특성 사례 연구)

  • Kim, Sung-Wook;Han, Byung-Won
    • Journal of the Korean Geotechnical Society
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    • v.26 no.7
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    • pp.171-186
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    • 2010
  • It is generally known that the mechanism of behavior in the flexible earth retaining system is relatively more complicated than in the rigid earth retaining system. Moreover in the case of long span strut supporting system the analysis of strut axial force change becomes more difficult when the differences of ground condition and excavation work progress on both sides of excavation section are added. When deeper excavation than the specification or installation delay of supporting system or change of ground condition happen during construction process, lots of axial force can be induced in some struts, which threaten the safety of construction. This paper introduces two examples of long span deep excavation where struts and rock bolts were used as a supporting system with flexible wall structure. The characteristics of ground deformation and strut axial force change, which were measured in the sections of two examples that are 50 meters apart in one construction site and have almost similar design and construction conditions were analysed, the similarity and difference between measurement results of two examples were compared and investigated. This article aims to improve and develop the technique of design and construction in future projects having similar ground condition and supporting method.

Moment-Curvature Relationship of Structural Wells with Confined Boundary Element (단부 횡보강된 구조벽의 모멘트-곡률 관계)

  • Kang, Su-Min;Park, Hong-Gun
    • Journal of the Korea Concrete Institute
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    • v.15 no.2
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    • pp.323-334
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    • 2003
  • For performance-based design using nonlinear static analysis, it is required to predict the inelastic behavior of structural members accurately. In the present study, a nonlinear numerical analysis was peformed to develop the method describing the moment-curvature relationship of structural wall with boundary confinement. Through the numerical analysis, variations of behavioral characteristics and failure mechanism with the arrangement of vertical reinforcement and the length of boundary confinement were studied. According to the analysis, the maximum moment-carrying capacity of structural walls with adequately confined boundary elements is developed at the moment the unconfined concrete reaches the ultimate compressive strain. Walls with flexural re-bars concentrated on the boundaries fails in a brittle manner. As vortical re-bars in the web increases, the brittle failure is prevented and a ductile failure occurs. Based on the findings, moment-curvature curves for walls with a variety of re-bar arrangement were developed. According to the proposed relationships, deformability of the structural walls wth boundary confinement increases as the compressive strength of the confined concrete increases compared to the applied compressive force.

Analysis of Monitoring Results and Back Analysis for Rigid Diaphragm Wall Supported by Ground Anchor (지반앵커로 지지된 강성 지하연속벽체의 상세계측 결과분석 및 역해석 평가)

  • Lee, Jong-Sung;Hwang, Eui-Suk;Cho, Sung-Hwan;Lee, Jun-Hwan
    • Journal of the Korean Geotechnical Society
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    • v.25 no.5
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    • pp.39-46
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    • 2009
  • In this study, behavior of a rigid continuous wall, earth pressure distribution with construction stage, and axial force of earth anchors were evaluated based on field monitoring data and numerical analysis results. For this purpose, a construction site excavated using the diaphragm wall was selected and full instrumentation system was introduced. From monitoring results, it was found that the values of horizontal displacement of the wall measured from the inclinometers, which were installed within the diaphragm wall were similar to analytical value. The earth pressure increased with excavation progress due to jacking force of the ground anchors installed in previous excavation stages. When the excavation depth reached 60% of the final depth, observed earth pressure distribution was similar to that estimated from Peck's apparent earth pressure distribution. When the excavation depth was around 90% of the final depth, values of observed earth pressure showed middle values between those of Peck's and Tschebotarioffs apparent earth pressures. It was also observed that, when excavation depth is deep, values of the earth pressures from the rigid wall were similar to those estimated from conventional earth pressure distribution shape proposed for flexible walls.

Correlation of Experimental ana Analytical Inelastic Responses of 1:12 Scale Irregular High-Rise RC Buildings (1:12축소 비정형 고층 RC 건물의 비선형거동에 대한 실험과 해석의 상관성)

  • Ko, Dong-Woo;Lee, Han-Seon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.2 s.54
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    • pp.95-104
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    • 2007
  • Three types of high-rise RC building structures having irregularity in the lower two stories were selected as prototypes and were performed nonlinear static analysis by using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. The first one has a symmetrical moment resisting frame (Model 1), the second has an infilled shear wall in the central frame (Model 2), and the third has an infilled shear wall only in one of exterior frames (Model 3). Fiber model, which consists of concrete and reinforcing bar represented from stress-strain relationship, is adapted used for simulate the nonlinearity of members, and MVLEM(Multi vertical linear element model) is used for simulate the behavior of wall. The analytical results are simulate the behavior of piloti stories well, for example, the stiffness and yield farce of piloti stories, the up-lift of wall and the variation of lateral stiffness of column due to the variation of axial forces. Overstrength of Model 2 and Model 3 are about 2 times larger than that of Model 1. The reason of the high oversttrength and ductility of Model 2 and Model 3 is that the conservative design of Model 2 and Model 3, whose beam and column sections are the same as those of Model 1. The ductilities of Model 1 and Model 3 are slightly larger than that of Model 1 and Model 3. Model 1 and Model 3 reached mechanism condition, whereas Model 2 failed to the shear failure of shear wall and the large axial forces in columns due to large overturning moment.