• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.72-77
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• 2000

In order to estimate strength of concrete, many attempts have been made. However, it is difficult to estimate concrete strength with ages. In this study, the factors influencing the strength of concrete such as w/c ratio and curing temperature, were investigated and results predicted by the established strength models were compared to measured strength data. It is found that in general the estimated values are approximate to the test results. In order to accurately predict the concrete strength curing temperature factor should be employed in the strength models.

• Fire Science and Engineering
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• v.3 no.2
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• pp.3-10
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• 1989

The results on high strength concrete by heating high are as follows: 1. High strength concrete appeared an estimated 5.5% higher than ordinary concrete in the central temperature of specimens by heating. 2. High strength concrete is higher than ordinary concrete in the decreased width of the ratio on the residual compressive strength by heating high. According to heating temperature and time, the inferred formula of compressive strength on high strength concrete showed: Fc=-0.53Te -2.4Ti +748.4

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.535-542
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• 2012

Adiabatic temperature rise test for predicting heat of hydration in mass concrete is especially inconvenient in the field. In order to overcome the problem, the equipment to effectively and conveniently measure semi-adiabatic temperature change was developed. The main objective of this paper is to propose a new and simple equipment for measuring semi-adiabatic temperature rise by using insulation bottles. In order to predict exact heat loss of concrete using this device, it is required to assume the specific heat loss coefficient of the device by water temperature change inside the experimental device. According to experimental and analytical results, the adiabatic temperature rise does not have significant differences in changes of temperature and humidity of air, as well as initial temperature of water. By comparing adiabatic temperature rise tests, the equipment for measuring semi-adiabatic temperature change can be used to predict the hydration heat of concrete within sufficient accuracy.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.4
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• pp.49-55
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• 2004

Properties of concrete using low heat portland cement is different from using ordinary portland cement and temperature of aggregate can be expected to have an important influence on its properties. In this study, experiment by setting up 5 levels (40, 30, 20, 4, $-2^{\circ}C$) by temperature of aggregate for evaluation properties of concrete using low heat portland cement was conducted. The experiments include slump test, air content test, change of slump, change of air content and compressive strength of concrete test. As the result of experiments, slump and air content was decreased by increasing temperature of aggregate. But it was not exceeding it's limit. Change of slump and air content was rapidly decrease by decreasing temperature of aggregate. At early age, compressive strength was influenced by the temperature of aggregate.

• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.61-66
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• 2011

Fire disasters have frequently happened in concrete structures, which resulted in severe structural damages and unsafety. In this case, the method which had evaluated the safety of damaged structures was often unaccepted from most of stakeholders and engineers. The objective of this study is to develope the procedure and method to be able to determine the safety. Numerical simulation was applied to produce the maximum temperature and temperature distribution. Nextly, temperature propagation analysis was performed to plot temperature gradients at each depth and location. The material strength curve versus temperature was applied to determine the safety of concrete structures damaged by fire. The maximum temperature should be calibrated considering real fire records ; magnitude, intensity, situation etc. The results shows that the selected procedure and method was applicable and practical.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1102-1105
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• 2008

In this paper, the prediction method of internal temperature for high strength concrete members at high temperature is presented. Finite element method is employed to facilitate thermal analysis for any position of member. In case of water evaporates inside the concrete member by high temperature, the evaporation heat that absorb surrounding temperature is occurred. This effect of the evaporation heat is applied. And the model equations of the material characteristics of high strength concrete by high temperature are proposed. To demonstrate the validity of this numerical procedure, the prediction by the proposed algorithm is compared with the test results of other researchers. The proposed algorithm is good agreement with experimental results including the phenomenon that temperature by the evaporation heat is lost.

• Computers and Concrete
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• v.27 no.1
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• pp.13-20
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• 2021

In this paper, the elevated temperature on a concrete-galvalume composite beam's flexural strength based on the numerical and experimental methods is investigated. The strategy is to perform modeling and simulation of the flexural test based on finite element method (FEM) at room temperature and validate its results to experimental data at the same temperature. When the numerical model was proven valid, the model was utilized to simulate the effect of elevated temperatures on the composite element. The study concludes that the flexural strength of the beam decreases at higher temperature. Additionally, it was shown that cracking moments is susceptible to temperature fluctuation and the failure modes are sensitive concerning the elevated temperature.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.122-126
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• 1999

In this study, using the temperature history analysis, the influences of the conductive values of wooden form, which are specified by Korean Standard for Concrete and ACI Practice Manual for Concrete, on the temperature history were examined. And, the calculated temperature history is compared with the measured temperature history. In the examination for the influences of the conductive values of wooden form, the value recommended by the Korean Standard can more closely predict the themperature history at the points which the variation of the boundary condition should be considered.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.174-181
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• 2000

A brief review of previous studies on the behaviour of concrete at extremely low temperature is presented in this paper. In addition, to describe temperature dependent behaviour of concrete, simple piecewise linear stress-strain relation is introduced. The proposed curve shows good agreement with experimental stress-strain curves at various temperature conditions. Moreover, numerical analyses for two PC beams are conducted to verify the influence of extremely low temperature to the structural behaviour.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.329-332
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• 1999

The crack of concrete induced by the heat of hydration is a serious problem, particularly in concrete structures such as underground box structure, mat-slab of nuclear reactor buildings, dams or large footings, foundations of high rise buildings, etc.. As a result of the temperature rise and restriction condition of foundation, the thermal stress which may induce the cracks can occur. Therefore the various techniques of the thermal stress control in massive concrete have been widely used. One of them is prediction of the thermal stress, besides low-heat cement which mitigates the temperature rise, pre-cooling which lowers the initial temperature of fresh concrete with ice flake, pipe cooling which cools the temperature of concrete with flowing water, design change which considers steel bar reinforcement, operation control and so on. The objective of this paper is largely two folded. Firstly we introduce the cracks control technique by employing low-heat cement mix and thermal stress analysis. Secondly it show the application condition of the cracks control technique like sidewall of LNG in Inchonl.