• 콘크리트학회논문집
• /
• 제12권2호
• /
• pp.3-11
• /
• 2000

There is a possibility of poor-state concrete filling condition due to segregation and interlocking of aggregate and paste when a high performance concrete is used at reinforced concrete structure without compaction. This study was conducted to evaluate the flexural behavior of high performance concrete beams with design parameters such as c, t and different concrete filling conditions. Different concrete filling conditions were intentionally made such that the first type specimen was soundly cast to obtain the perfect concrete filling condition. Second type was cast in such a way that up to the longitudinal tensile reinforcement from the top, good concrete was filled while poor concrete was poured for the bottom part to simulate the poor strength, workability and unsatisfactory compaction. Third type was cast in such a was that up to the neutral axis of the beam section from the top, good concrete was filled while so did for the bottom part as the second type. The test results were analyzed in terms of load-displacement response, failure pattern, crack width and crack spacing. The test results indicate that have no effect of concrete filling conditions on the yielding strength of structures. But, have a grate influence on the stiffness and ductility of structures.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
• /
• pp.306-311
• /
• 1996

This paper persents the flexural behavior of high performance concrete beams having different concrete filling conditions. Three tests were conducted on full-scale beam specimens with design concrete compressive strength of 400 kg/$\textrm{cm}^2$. Different concrete filling conditions were intentionally made such that the first beam specimen was soundly cast to obtain the perfect concrete filling condition. Second beam specimen was cast in such a way that up to the longitudinal tensile reinforcement from the top, good concrete was filled while poor concrete was poured for the bottom part to simulate the poor workamanship, workability and unsatisfactory compaction. Third beam specimens was cast in such a way that up to the neutral axis of the beam section from the top, good concrete was filled while so did for the bottom part as the second beam specimen. The test results were analyzed in terms of load-displacement response, formation of crack, crack width, crack spacing and shift of neutral axis. An evaluation of the ductile response fo three different beam specimens was made in combination with the ultimate load accoding to the three different concrete filling conditions.

• 한국구조물진단유지관리공학회 논문집
• /
• 제12권1호
• /
• pp.143-150
• /
• 2008

철근콘크리트 구조물에서 배근상태에 따라서는 다짐불량에 의한 재료분리 및 골재폐쇄현상이 발생하여 채움이 제대로 되지 않는 경우가 발생할 수 있다. 본 연구에서는 그 영향을 충분히 고려하지 않고 있는 재료분리에 따른 중립축이하 인장부 콘크리트가 보부재 거동에 미치는 영향 파악을 위한 실험을 수행하여, 보부재의 인장 철근영역 콘크리트의 유효성 파악을 위한 연구를 수행하였다. 실험결과 인장철근영역 콘크리트의 재료분리에 따른 거동은 부재항복강도에는 미치는 영향이 없으나, 부재 휨연성, 전단저항능력을 저하시키는 것으로 나타났다.

• Advances in concrete construction
• /
• 제2권3호
• /
• pp.209-227
• /
• 2014

The use of limestone fines (LF) in mortar and concrete can in certain ways improve performance and thus has become more and more commonplace. However, although LF is generally regarded as a filler, it is up to now not clear how much filling effect it could have and how best the filling effect could be utilized. Herein, the packing density and filling effect of LF were studied by measuring the packing densities of LF, (LF + cement) blends and (LF + cement + fine aggregate) blends under dry and wet conditions, and measuring the performance of mortars made with various amounts of LF added. It was found that the addition of LF would not significantly increase the packing density of (LF + cement) blends but would fill into the paste to increase the paste volume and paste film thickness, and improve the flow spread and strength of mortar.

• 한국압력기기공학회 논문집
• /
• 제16권1호
• /
• pp.37-41
• /
• 2020

The Nuclear containment building is a main safety-related structure that performs shielding and conservation functions to prevent highly radioactive materials from leakage to the outside environment in the case of various environmental conditions and postulated accidents. The containment building contains a reactor, steam generator, pressurizer, tank, reactor coolant system, auxiliary system and engineering safety system, and is designed so that highly radioactive materials above the limits specified in 10 CFR 100 do not escape to the outside environment in the case of LOCA(Loss of Coolant Accident) for instance. The containment metal liner plate(CLP) is a carbon steel plate with a nominal plate thickness of 6 mm, which functions as a mold for the wall and dome of the containment building when concrete is filled, fulfills airtightness to prevent leakage of seriously radioactive materials. In recent years, backside corrosion was found on the liner plate in some domestic nuclear power plants. The main cause of backside corrosion was unfilled concrete. In this paper, an inspection technique of assessing filling suitability for CLP backside concrete is developed. Results show that the validity of inspection technique for CLP backside concrete using vibration sensor is successfully verified.

• Advances in concrete construction
• /
• 제14권2호
• /
• pp.139-151
• /
• 2022

Filling materials poured into precast member joint are subjected to restraint stress by the precast member and joint reinforcement. The induced stress will likely cause cracks at early ages and performance degradation of the entire structure. To prevent these issues and design reasonable joints, it is very important to analyze and evaluate the restrained shrinkage cracks of filling materials at various restraint conditions. In this study, a new time zero-that defines the shrinkage development time of a filling material-is proposed to calculate the accurate amount of shrinkage. The tensile stresses and strengths at different ages were compared through the ring test (AASHTO PP34) to evaluate the crack potential of the restrained filling materials at various restraint conditions. The mixture which contained an expansive additive and a shrinkage reducing agent exhibited high resistance to shrinkage cracking owing to the high-drying shrinkage compensation effect. The high-performance, fiber-reinforced cement composite, and ultra-high-performance, fiber-reinforced cement composite yielded very high resistance to shrinkage and cracking owing to the pull-out property of steel fibers. To this end, multiple nonlinear regression analyses were conducted based on the test results. Accordingly, a modified tensile stress equation that considered both the geometric shape of the specimen and the intrinsic properties of the material is proposed.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
• /
• pp.363-366
• /
• 1999

This paper describes the behavior of prestressed concrete storage tanks under cryogenic temperatures by thermal stress analysis. In concrete tanks to store up LNG, a thermal shock can occur over a global area resulting from the sudden filling of the outer tank with cryogenic storage contents. Analysis results show that internal surface of concrete tank is cooled down rapidly. Tank is subjected mostly to thermal constraint moment due to temperature gradient across its section. Constraint moment may cause tensile stresses beyond tensile strength in the wall. Problems related with concrete cracking due to temperature gradient have been considered.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
• /
• pp.418-421
• /
• 2006

Appropriate analysis models for concrete-filled steel tube (CFT) subjected to bending moment were determined to assess flexural behavior of CFT member. Applying this model, finite element analyses was performed and compared against experimental data considering the compressive strength of in-filling material and the composite action between tube shell and in-filling core. Analysis results showed that the FE model proposed in this study is feasible for the analytical investigation of the flexural behavior of CFT member according to loading conditions, effect of compressive strength of various core materials and other design parameters.

• 한국건축시공학회지
• /
• 제4권3호
• /
• pp.93-100
• /
• 2004

In recent years, it has widely been studied on the light-weight composites for the purpose of the large space and thermal insulation of building structures. The purpose of this study is to evaluate the properties of light-weight composites made by binders as cement, resin and polymer cement slurry. The concrete composites are prepared with various conditions such as polymer-cement ratio, void-filling ratio, type of resin, filler content and light-weight aggregate content, tested for thermal conductivity. From the test results, the thermal conductivity of concrete composites with the binder of cement tends to decrease with increasing polymer-cement ratio, and to increase with increasing void-filling ratio. The thermal conductivity of concrete composites with the binder of resin are markedly affected by the light-weight aggregate content, type of resin and filler content. The composites made by polymer-modified concrete and polymer cement slurry have a good thermal insulation property. From the this study, we can recommend the proper mix proportions for thermal insulation Panel or concrete. Expecially. the thermal conductivity of concrete composites made by polyurethane resin is almost the same as that of the conventional expanded polystyrene resin.

• 국제초고층학회논문집
• /
• 제2권1호
• /
• pp.11-21
• /
• 2013

The use of concrete filling offers a practical alternative for achieving the required stability of steel Hollow Structural Section (HSS) columns under fire conditions. However, current methods for evaluating fire resistance of Concrete Filled Hollow Structural Steel (CFHSS) columns are highly conservative as they are based on an elemental approach without due consideration to structural interactions that occur in framed structural systems. To overcome this limitation, a system level fire resistance analysis was carried out by treating CFHSS columns as part of an overall structural frame. In this analysis, an eight story steel-framed building was modeled under a range of standard and performance-based fire scenarios (including multi-story progressive burn-out fires) to evaluate the contribution of various structural members/assemblies to overall fire resistance. One of the primary factors considered was the use of concrete filling in HSS columns as an alternative to standard W-shape columns. Results from the analysis indicate that the use of CFHSS columns, in place of W-shape columns, in a performance-based environment can fully eliminate the need for applied fire protection to columns, while providing the required level of structural fire resistance.