• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1081-1086
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• 2010

The general soil nailing support system may result in excessive deformations particularly in an excavation zone of the existing weak subsoils. Pretensioning the soil nails then, could play important roles to reduce deformations mainly in part of the nailed-soil excavation system as well as to improve local stability. Morever, soil nails are installed underneath roads, underground structures, and subway structures, thereby resulting in difficulties in nail remval after completion of temporary soil nailed walls. Hence, to date, in order to solve the technical difficulties and avoid legal issues related to the construction of soil nails underneath the surrounding areas and structures, the removable soil nailing system has been developed and used. But, Therefore, a new soil nailing technique called Removable Post-tensioned Soil Nailing(RPTN) system has been developed in the current study. In this study, an investigation of the RPTN system has been conducted by carrying out field measurement. Hence, the RPTN system can reduce ground displacement and enhance stability of the soil nailed walls.

• 한국공간구조학회논문집
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• 제20권1호
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• pp.41-48
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• 2020

In this study, the design of anchorage zone for unbonded post-tensioned concrete beam with single tendons of ultimate strength 2400MPa was evaluated to verify that the KDS 14 20 60(2016) and KHBDC 2010 codes are applicable. The experimental results showed that the bursting force equation of current design codes underestimated bursting stress measured by test, because the KDS 14 20 60(2016) and KHBDC 2010 propose the location of the maximum bursting force 0.5h which is the half of the height of member regardless of stress contribution. Although the allowable bearing force calculated by current design codes was not satisfied the prestressing force, the cracks and failure in anchorage zone was not observed due to the strengthening effect of anchorage zone reinforcement.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.126-129
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• 2006

A bending moment $M_u$ transferred at slab-column connection is resisted at the slab critical section by flexure and shear. The ACI 318-05 Building Code(1) gives an empirical equation for the fraction ${\gamma}_{\upsilon}$ of the moment $M_u$ to be transferred by shear at the slab critical section at d/2 from the column face and also the effective wide(c+3h). The equation is based on tests of interior slab-column connections without shear reinforcement. In order to investigate the data eight test specimens were examined. The test shows that increased slab load substantially reduces both the unbalanced moment capacity and the lateral drift capacity of the connection. Especially, the specimens with the bottom reinforcement existence and nonexistence, appears remarkable differences. Studies also show that the code equation for ${\gamma}_{\upsilon}$ does not apply to all cases. The purpose of this study is to compare the test results with present ACI 318-05 Building Code provisions for design of slab-column connections and with the analysis of the experimental data for a new limitation of strength equation without shear reinforcement and bottom reinforcement.

• 한국공간구조학회논문집
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• 제15권1호
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• pp.57-64
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• 2015

This paper shows the test results of continuous reinforced concrete beams with external post-tensioning rods. Six three-span beams were prepared and tested to fail. Three beams were designed to have flexure-dominating behavior and the others to have shear-critical behavior. In each group, one beam without external post-tensioning rods was designated as a control beam and two beams had the external post-tensioning rods of 18 mm or 22 mm diameter. External post-tensioning rods were installed within an interior span of 6000 mm. They show V-shaped configuration because two anchorages were located at the top of interior supports and a saddle pin at mid-span was installed at the bottom of the beam. Test results show that the load and shear capacities of strengthened beams were increased when compared with the control beam. Additionally, the measured shear strength was compared with the strength predicted by ACI 318-11 code equations. The detailed ACI 318-11 equation predicted the measured shear strength and failure location of the continuous beam reasonably well.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.668-673
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• 1998

The specimen of current study has the same type with the 3-span slabs of Burns et al used in the study by Mojtahedi/Gamble, which laid a ground for the revision of the ACI318-77 code to the ACI 318-83 code. But those specimens was failed prematurely before it reached the ultimate strength which the specimen had. The reason is that bonded reinforcements were cut off where there is no need for the flexural reinforcement. As results. the slabs failed ultimately where the reinforcements was cut off. Thus, the tendon stresses of failure may have been much smaller than the values which culd reach if the bonded reinforcements were extended beyond the theoretical cut off points. On the based on the fact mentioned above. the specimens which had the same conditions as the specimens of Burns et al were used in the current study, but in which the reinforcements were distributed in a sequence for the reinforcements not to be cut anywhere in the 3-span. As a results, it was known that the current ACI code, revised by the result of Mojtahedi/Gamble's study, overestimated the effect of span/depth ratio on the members with high span/depth ratio. Thus it was concluded that the effect of span/depth ratio on the ultimate stress of unbonded tendon regulated by the current ACI code must be reconsidered and reevaluated.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.31-34
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• 2009

Large outrigger elements tie the concrete core to perimeter columns, significantly increasing the building's lateral stiffness as well as its resistance to overturning due to wind. The outriggers are deep elements, and large tie forces are resisted by top and bottom heavy longitudinal reinforcing and vertical ties. To reduce construction costs, all primary reinforcing bars in outrigger levels are SD500. Further, concrete strengths of 80MPa have been specified for outrigger elements. However, the reductions in the amount of concrete and reinforcement steel are more increased in tall building. With these backgrounds, 80MPa high strength concrete outrigger system using post tension method is developed. Significant economic savings can be made by reducing the element sizes and material content. The developed outrigger system is designed using strut-and-tie models. In addition, four 1/4-scale test specimens were selected from the same prototype structure. The results from the tests are confirmed that the structural behaviors of the developed outrigger member have better capacities than those of a conventional method.

• 대한건축학회논문집:구조계
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• 제34권10호
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• pp.3-10
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• 2018

Hybrid Prestressed Precast Concrete System (HPPC system) is a newly developed frame system that can improve the performance of precast concrete (PC) joints by post-tensioning. In particular, the details proposed in this study can reduce the lifting weight of the PC members and eliminate problems caused by cracks in the joints that occur under service loads. This study performed an evaluation on the negative moment performance of full-scaled HPPC girders. The test specimens were cast with or without slabs, with bonded or unbonded tendons, and had different post-tensioned lengths in tensile section. The test results showed that the specimens with slabs had significantly higher stiffness and strength than those without slabs. There were no differences in the flexural behavior between those with bonded or unbonded tendons, and between those with short or long post-tensioned lengths in the negative moment region.

• 한국구조물진단유지관리공학회 논문집
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• 제13권3호통권55호
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• pp.181-187
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• 2009

본 논문은 압축력 흡수장치를 사용하지 않은 프리스트레스 보강공법의 단점을 보완한 Bow 공법에 대한 연구이다. 본 논문의 목적은 장기 하중이 작용할 때 발생할 수 있는 프리스트레스의 손실 등에 대하여 분석하는 것이며, 또한 Bow 공법으로 보강한 부재의 성능 향상에 대한 자료를 제시하는 것이다. 이상의 목적을 달성하기 위하여 경간/깊이 비, 긴장재 양을 변수로 실험체를 제작하여 실험을 실시하였다. 그리고 장기 하중 재하 실험도 실시되었다. 실험결과에 의하면 Bow 공법은 현행의 설계규준을 적용하여 설계할 수 있음을 확인하였으며, 장기 하중 재하에 의하여도 구조적인 문제가 없는 것으로 확인하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.135-140
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• 2001

A post-tensioned reinforced concrete slab bridge is analyzed by specially orthotropic laminate theory. Symmetrically reinforced slab with tension and compression steel is considered for convenience of analysis. Each longitudinal and transverse steel layer is regarded as a lamina, and material constants of each lamina is calculated by the use of the rule of mixture. This bridge is under uniformly distributed vertical loads, and axial loads and end moments due to post-tensioning. In this paper, finite difference method is used for numerical analysis of this bridge. Theory and analysis method of specially orthotropic laminate plates used in this paper can be used for design of new bridges, and maintenance and repair of old bridges.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.141-146
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• 2001

A post-tensioned steel plate girder bridge with cross-beams is analyzed by specially orthotropic laminate theory. The cross-sections of both girders and cross-beams are WF types. The result is compared with that of the beam theory. This bridge with simple support is under uniformly distributed vertical load, and axial loads and moment due to post-tension. In this paper, finite difference method for numerical analysis of simple supported bridge is developed. Relatively exact solution is obtained even with small number of meshes. Theory and analysis method of specially orthotropic laminate plates used in this paper can be used in design of new bridges, and maintenance and repair of old bridges.