• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.79-80
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• 2016

In this study, we measured the relative density and the compressive strength in order to select the appropriate W/ B for the ultra-high strength concrete development. If W/B is lowered than the W/B of highest relative density, it was confirmed that the strength is lowered. However, if water is increased than the W/B of highest relative density, the relative density is decreased compressive strength was similar. The selection of the W/B of the lower than the highest relative density is not appropriate. Appropriate W/B is selected to be more than the maximum relative density of W/B.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.53-54
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• 2016

In this study, the effect of high temperature on the compressive strength and elastic modulus of ultra high strength concrete with PP fiber were experimentally investigated. As the result, the compressive strength and elastic modulus of ultra high strength concrete were irrespectively evaluated mixed ratio of PP fiber at high temperature.

• Land and Housing Review
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• v.4 no.3
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• pp.295-301
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• 2013

In this study, cases of domestic tall residential buildings were investigated for the structural types, numbers of stories, total heights, type of lateral load resisting systems, and zoning of concrete strength. Based on these investigation data, the structural planning pattern of tall residential building was analyzed. SRC structure is main structural types of tall residential building at the initial stage of domestic tall residential building, but RC structure is substituted for main structural types since 2005. Retaining wall system is positioned at the core part of structural plan as a lateral load resisting system. Concrete strength zoning of vertical members like columns are divided by vertical heights of lower parts, middle parts, and upper parts. Basic data of structural planning of 40stories and 60 stories residential buildings was proposed based on case investigation.

• Journal of the Korea Concrete Institute
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• v.21 no.1
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• pp.13-20
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• 2009

The influence of steel fiber volume on the tension softening behavior in steel fiber-reinforced ultra high strength concrete was investigated. Three-point bending test (TPBT) with notched beams was performed and inverse analysis method by Uchida et al. was adopted to obtain the tension softening behaviors from the results of TPBT. It could be found that the intial stiffness was constant regardless of steel fiber volume, the increase of steel fiber volume fraction made the tensile strength higher, but all of the curves converged on an asymptote with a crack width. It was proposed the equation of softening curve expressed by combination of plastic behavior part and exponential descending behavior part considering the steel fiber volume fraction and $\omega_0$, which is corresponding to the maximum crack width of plastic area. Thereafter, the crack propagation analysis using finite element method with smeared crack model was also carried out and it was confirmed that the proposed equation had a good agreement with the experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.139-148
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• 2015

The purpose of this paper is to induce the ductile behavior of the UHPFRC member after the peak load by using the bundle of longitudinal reinforcing bar as a substitute for steel fiber. Experiments on the flexural behavior of the Ultra High Performance Concrete rectangular beam with the combination of the steel fiber and longitudinal reinforcing bar were carried out. The volume fractions of steel fiber are 0%, 0.7%, 1%, 1.5%, 2% and the reinforcement ratios of longitudinal reinforcing bar which induce the ductile behavior are 0.0036, 0.016, 0.028 and 0.036. 15 UHPC beams were made with the combination of these test factors. Not only steel fiber but also bundle of longitudinal reinforcing bar has the effect to induce ductile behavior of UHPC structural member. The combination of 0.7% volume fraction of steel fiber and 0.028 reinforcement ratio showed the most economic combination. The relationship of load-deflection, strain variation of the concrete and the crack pattern indicate the usefulness of the bundle of the longitudinal bar which has small diameter with close arrangement each other.

• Journal of the Korea Institute of Building Construction
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• v.19 no.3
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• pp.229-237
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• 2019

This study examines the estimation of strength through a ultra-high strength concrete mock-up specimen using the rock compressive strength test hammer. According to the test result, the commonly used strength estimation formulae showed differences among them when the data of this test were applied. In additional, it show that these formulae underestimated the actual measurements further when the compressive strength was 30MPa or greater and deviated the distribution range of actual measurements in all strength ranges. The rock test hammer showed a higher correlation than type N Schmidt hammer regardless of the direction of hit for each type of W/B and the inclusion of coarse aggregate, and mortar showed a little higher correlation than concrete. As a result, it can be suggested that the coefficient of variation and the standard deviation of the mortar(2.26%/1.36) are lower than those of the concrete(4.06%/2.5), and the smaller the size of the coarse aggregate, the smaller the coefficient of variation and the more accurate the value.

• Journal of the Korea Institute of Building Construction
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• v.6 no.3 s.21
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• pp.123-129
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• 2006

In these days, as building structures are getting taller, larger, and more diversified, structural systems with more economy and more efficiency are being required and so are more efficient building materials, this study conducted a basic experiment to conclude an adequate selection of materials and to calculate an optimal mixing proportion of those materials to produce High-strength concrete in a 100MPa of specified concrete strength. And also we conducted an experiment to find out basic properties of this concrete such as slump-flow, strength.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.382-385
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• 2011

본 논문은 초고강도콘크리트의 폭렬현상을 연구해 보고자 실리카흄 유무와 PP섬유의 혼입량을 변수로 하여 공시체와 벽체의 폭렬현상을 관찰한 후 변수가 초고강도콘크리트에 어떠한 영향을 주는지를 실험적으로 규명하는 것을 목적으로 하였다. KS F 2257 화재온도이력곡선을 30분 적용하여 콘크리트의 초기 폭렬특성을 실험적으로 검토하였다. 그 결과 공시체의 경우 압축강도가 100 MPa 초고강도콘크리트의 경우에는 실리카흄 여부와 PP섬유 혼입량이 폭렬억제에 관계되는 주요 인자인 것을 알 수 있었으며, 벽체의 경우에는 벽체 시험체의 부분 가열 및 전면 가열 실험을 실시했다. 폭렬 최대 깊이, 시간, 소리 발생 회수를 비교하면 부분 가열이 전체 가열에 비해 폭렬이 빠르고 깊게 발생하는 것으로 나타났다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.26-27
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• 2014

Study on high temperature properties of concrete and internal force estimation of structural member subjected to high temperature mainly applied high temperature strength model based on experimental results with concrete under 40MPa. However, it is reported that degradation of internal force at high temperature and spalling of ultra high strength concrete are higher than that of normal strength concrete. Therefore, this study attempts to propose compressive strength degradation model which is suitable to ultra high strength concrete comparing to existing model by evaluating high temperature properties of ultra high strength concrete.

• Magazine of the Korea Concrete Institute
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• v.18 no.5 s.94
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• pp.59-64
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• 2006