• Journal of Welding and Joining
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• v.22 no.4
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• pp.50-58
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• 2004

In this study, high temperature tensile properties of high strength steels(POSTEN60, POSTEN80) were investigated. The three-dimensional thermal elastic-plastic analyses were conducted to investigate the characteristics of welding residual stresses in welds of high strength steels on the basis of thermal and mechanical properites at high temperature obtained from the experiment. According to the results, high temperature tensile strength of POSTEN60 steel deteriorated slowly to 10$0^{\circ}C$. As the temperature went up, the tensile strength became better because of blue shortness, and it deteriorated radically after reaching to the maximum value around 30$0^{\circ}C$. For the POSTEN80 steel, high temperature tensile strength deteriorated slowly to 20$0^{\circ}C$. As the temperature went up the tensile strength became better and it deteriorated slowly to $600^{\circ}C$ after reached to the maximum value around 30$0^{\circ}C$. Strain of high strength steels at the elevated temperature increased radically after the mercury rose to $600^{\circ}C$. The strain hardening ratio of POSTEN60 steel was larger then that of POSTEN80 steel at the elevated temperature as in the case at the room temperature and it became smaller radically after the mercury rose to 40$0^{\circ}C$. And, in the welding of high strength steels, increasing tensile strength of the steel (POSTEN60

• 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.

• Journal of the Korea Institute of Building Construction
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• v.2 no.4
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• pp.163-168
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• 2002

The object of this study is to define the characteristics of high performance concrete with varing compressive strength of concrete and curing temperature. The major test variables are 1) high strength concrete(500kg/$cm^2$) and ordinary strength concrete(240kg/$cm^2$) compressive strength, 2) curing temperature and condition, 3) concrete curing age, 4) three types of cement. From the test results were shown that curing temperature and curing conditions were also very effective for high strength concrete and ordinary strength concrete, and concrete were largely effected by cement type and temperature during the hydration reaction process. This paper describes the effect of curing temperature for strength and characteristics of high performance concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.25-28
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• 2005

The experimental results on the mechanical behavior of high-strength concretes subjected to high temperature were presented. Main variables were heating temperature, heating continuance time, and cooling condition. The compressive strength properties of high strength concrete(HSC) varied differently with temperature than those of normal strength concrete(NSC). HSC had higher rates of strength loss than NSC in the temperature range of between $20^{circ}C$ and $400^{circ}C$. Especially, HSC exploded in $400^{circ}C$ of high temperature.

• Journal of the Korea Institute of Building Construction
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• v.8 no.4
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• pp.115-121
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• 2008

The present study performed low-pressure steam curing with mortar specimens in order to examine the temperature profile and strength development of steam curing in high-strength specimens of 100MPa. In addition, as a basic research to utilize PC products, we examined the effects of curing temperature and time in steam curing cycle on strength development resulting from the hydration of cement within the range of high strength by changing four factors affecting the quality of PC displacement time, peak curing temperature, peak temperature duration, and ascending and descending gradient of temperature - in various patterns, and analyzed the optimal strength development characteristic based on the relation between temperature profile and strength development. With regard to the high-temperature curing characteristic of PC, we performed an experiment on the strength characteristic according to the temperature profile of high-strength mortar, and from the results of the experiment according to curing characteristic, displacement time, peak curing temperature, peak temperature duration, and ascending and descending gradient of temperature, we drew conclusions as follows.

• Proceedings of the KWS Conference
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• 2003.05a
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• pp.260-262
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• 2003

In this study, high temperature tensile properties of high tensile strength steels(POSTEN60, POSTEN80) were investigated by elevated temperature tensile test. According toe the results, high temperature tensile strength of POSTEN60 deteriorated slowly to 100$^{\circ}C$. As the temperature went up the tensile strength became better because of blue shortness and it deteriorated radically after reached to the maximum value around 300$^{\circ}C$. For the POSTEN80, high temperature tensile strength deteriorated slowly to 200$^{\circ}C$.As the temperature went up the tensile strength became better and it deteriorated slowly to 600$^{\circ}C$ after reached to the maximum value around 300$^{\circ}C$. Strain of high tensile strength steels at the elevated temperature increased radically after the mercury rose to 600$^{\circ}C$. The strain hardening ratio of POSTEN60 was larger then that of POSTEN80 at the elevated temperature as in the case at the room temperature and it became smaller radically after the mercury rose to 400$^{\circ}C$.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.413-421
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• 2014

Since the structural temperature of a flight vehicle flying at high speed rises rapidly due to aerodynamic heating, it is necessary for optimum structural design to obtain proper material properties at high temperature by taking into account of its operational environment. For a special alloy, analysis data on strength change due to exposure time to high temperature are very limited, and most of them are for an exposure time longer than 30 minutes for long term operations. In this study, base and weld metal samples of Ti-6Al-4V alloy had been prepared and high temperature tensile tests with induction heating were performed, and then high temperature strength characteristics and strength recovery characteristics through cooling have been analyzed. Pre-tests to determine maximum heating rate were performed, and response characteristics for temperature control were confirmed. As a result, high temperature tensile strength appeared to be lower than that of room temperature, but it was higher than that of high temperature of 30 minite exposure listed in MMPDS. In strength recovery through cooling Ti-6Al-4V alloy has shown higher recovery rate compared with other alloys.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.45-48
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• 2005

This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressive strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of qualify control. According to the result of cement mortar by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.56-57
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• 2013

In this study, in regard to concrete considering variety of admixture content rate, we evaluated property of adiabatic temperature rise. By setting up high temperature history, we evaluated effect to compression strength property of high strength concrete by early high temperature history. As a result, early high temperature history accelerated Hydration reaction of cement and contribute early strength development but it didn't accomplish performance objective in long-term aged.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.86-87
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• 2017

The high-temperature creep of Ultra-High-Strength Concrete (UHSC) has been investigated in this study. The purpose of this study is to evaluated total strain and high-temperature creep at elevated temperatures under loading condition of UHSC. As results, Total strain of UHSC increased showing shrinkage with increasing compressive strength. The high-temperature creep of UHSC increased with the temperature and higher level of compressive strength showed bigger high-temperature creep.