• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.1 s.53
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• pp.37-43
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• 2007

Experiments for circular unreinforced concrete beams confined by carbon fiber tubes (CFT) made of carbon fiber sheets were performed. Selected test parameter was thickness of carbon fiber tube: 1.5mm (3 layers), 2.0mm (4 layers), 2.5mm (5 layers), and 3.0mm (6 layers). Based on the test results, an equation for estimating moment capacity of the circular beams confined by carbon fiber tubes was proposed. Comparison results showed good agreement up to 2.5mm (5 sheets) of the CFT thickness.

• Magazine of the Korea Institute for Structural Maintenance and Inspection
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• v.18 no.4
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• pp.2-8
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• 2014

본 고는 동절기 이후 무근 콘크리트의 상부에서 쉽게 발생하는 스케일링 현상에 주목하여 무근 콘크리트의 동해 발생원인을 고찰하고, 이에 대한 내구성을 향상시키기 위한 방안을 기존문헌조사를 통하여 1) 강도향상, 2) 진공배수공법 적용, 3) 흡수방지재 시공의 방법을 선정하였다. 그 후 각 방법의 동결융해저항성 향상 평가를 정량적으로 평가하기위하여 동결융해 시험을 통한 상대동탄성계수를 측정하였다. 그 결과 1), 2)번의 경우 동탄성계수가 약 15% 향상, 3)의 경우 강도에 따라 7~13%향상됨을 실험적으로 확인하였다. 따라서 상기의 방법 모두 무근 콘크리트의 동결융해 저항성 향상에 유효한 방법으로 판단되며, 이를 통해 무근콘크리트의 빈번히 발생하는 품질저하 및 이로인한 유지보수비용 절감을 도모할 수 있을 것으로 사료된다.

• Journal of the Korea Institute of Building Construction
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• v.18 no.3
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• pp.243-249
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• 2018

The study for curling control of plain concrete in underground parking lot was conducted in this study. The shrinkage reducing agent(SRA) was used to minimize the curling deformation of plain concrete in underground parking lot. For the quantitative curling control, the simplified prediction method applying the deflection theory of cantilever beam was proposed too, and the validity of prediction method was examined through the comparison between the experimental values and predictive values. In result, the curling of SRA 1.0% concrete was about 30% less than that of SRA 0.0% concrete, and the possibility of curling estimation by the simplified prediction method was confirmed through the comparison between the experimental values and predictive values.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.15-17
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• 2009

송전선로 철탑은 비교적 작용하는 하중이 크고 바람과 피빙의 영향을 많이 받는 구조물로써 이를 안정적으로 지탱하기 위해서는 튼튼한 기초를 필요로 한다. 그러나 무근콘크리트 기초는 재료의 특성상 휨인장력에 대하여는 지지력이 없어 철탑기초로는 부적절한 구조물이다. 본 고에서는 무근콘크리트 기초에 대한 철근 콘크리트 보강공법 시공기술에 대하여 고찰하고자 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.171-181
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• 2003

This study concerns the prediction of shear capacity, as governed by concrete breakout failure, concrete pryout failure and steel failure, of single anchors located close to free edge and located far from a free edge and installed in uncracked, unreinforced concrete. For this purpose, the methods to evaluate the shear capacity of the single anchors in concrete are summarized and the experimental data are compared with capacities by the two present methods: the method of ACI 349-90 and concrete capacity design (CCD) method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.85-86
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• 2016

Recently damages caused by the additional costs and degradation in durability combined deterioration due to plain concrete deterioration has occurred. In particular, in the case of the finish that is not exposed to the outside air in the concrete to respond to the harsh environment (freeze-thawing, calcium laying, etc.), to establish a quality control way for the process and the concrete mix design for it.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.5 s.51
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• pp.1-9
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• 2006

In this study, axial and lateral loading experiments for both circular and square plain concrete columns confined with carbon fiber tube manufactured by carbon filament winding technique were performed. Based on the test results, reliability analyses to estimate strength reduction factors were carried out by utilizing Monte Carlo technique. CASE I was for plain concrete columns confined with the carbon tubes, CASE II was for reinforced concrete columns confined with the carbon tubes. As results, the strength reduction factors, ${\phi}$, were estimated as 0.7 for CASE I and 0.85 for CASE II respectively.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.649-660
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• 2003

The paper presents an evaluation of the tensile strength of the expansion anchor that can cause failure in the concrete based on the design of the anchorage. Tests of the heavy-duty anchor and the wedge anchor that are domestically manufactured and installed in plain concrete members are conducted to probe the effects of the embedded depth, concrete strength, and anchors spacing. The design of post-installed steel anchors is presented using the Concrete Capacity Design (CCD) approach. The CCD method is applied to predict the concrete failure load of the expansion anchor in plain concrete under monotonic loading for important applications. The concrete tension capacity of the fastenings with heavy-duty anchors and wedge anchors in plain concrete predicted using the CCD method is compared with the test results. For the CCD method, a normalization coefficient of 9.94 is appropriale for the nominal concrete breakout strength of an anchor or a group of wedge anchors in tension. On the other hand, a normalization coefficient of 11.50 is appropriate for the nominal concrete breakout strength of an anchor or a group of heavy-duty anchors in tension.

• 레미콘
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• no.6 s.4
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• pp.2-15
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• 1985

• Magazine of the Korea Concrete Institute
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• v.5 no.3
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• pp.179-186
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• 1993

본 연구는 무근 폴리에스터 폴리머 콘크리트보의 휨피로 거동을 구명키 위한 것으로서 초기균열깊이와 높이의 비 (a/h)를 0, 0.2, 0.4로 하고 응력수준을 45%, 55%, 65%로 하여 피로 시험을 실시한 것이다. 그 결과 초기균열깊이가 커질수록 피로수명이 짧아졌으며, 피로수명비에 따른 휨인장변형도는 균열깊이가 클수록 작아졌다. 또한 휨탄성계수는 피로수명비 0.2에서 0.6정도까지는 선형적인 변화를 보였으나, 초기와 말기에는 비선형적인 변화를 보여주었다. 그리고 응력수준과 균열깊이가 커질수록 취성적인 성질이 더 크게 나타남을 알 수 있었다.