• Fire Science and Engineering
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• v.32 no.2
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• pp.48-56
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• 2018

This paper reports the results of a study on the over-current characteristics of IV insulated wire sheath according to accelerated degradation. In order to examine the degradation of a IV insulated wire sheath through insulation, acceleration degradation experiments were performed using the Arrhenius equation of acceleration life test models; test samples with equivalent lives of 0, 10, 20, 30 and 40 years were prepared. Then allowed currents with over-current of 100%~500% were introduced to measure the times of first generation of smokes and carbonization in the wire sheath, and it was found that the times of first generation of smokes and carbonization in the wire sheath decreased as the equivalent life increased. In more detail, when 270% over-current is applied, the electrical fire risk of equivalent life of 40 years increased by approximately 3.2 times based on equivalent life of 0 years. Also, when the over-current was 255% and 260%, carbonization occurred only in the equivalent life of 40 years, and the fire risk according to the accelerated degradation was increased dramatically. In addition, FT-IR and SEM analyzes were used to confirm the characteristics and surface changes of IV insulated wire sheath according to the equivalent life.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.609-619
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• 2004

An investigation was conducted on the activities around Europe in order to solve the problem of the thermal bridging of steel studs, which had caused a significant disadvantage. This study included the following: diminishing the contact area between the studs and the sheathing, lengthening the heat transfer route, replacing the steel web with a less conductive material, and placing foam insulation in locations where the thermal shorts are most critical. Although energy efficiency is usually the focus of such foreign cases because their stud application is mostly limited to low-rise residential buildings, both structural and thermal performance are taken into consideration in this study because these target middle-story buildings. A hybrid stud composed of steel and polymer was also developed. This hybrid stud, which is 150 SL in size, is made of a galvanized steel sheet (SGC58) and a glass fiber reinforced polymer (GFRP) withepoxy bonding. A total of 32 specimens were manufactured. Its parameters comprise two types of connection detail,s: the thickness of steel (1.0mm and 1.2mm) and of the GFRP (4mm-4ply and 6mm-6ply), and the ratio of the length to the depth (L/D = 3, 6, 9, 12). Steel stud specimens with the same conditions were compared to the hybrid stud. The test revealed that in the case of the steel specimen with a thickness of 1.0mm, the maximum load of hybrid studs increased an average of 1.62 times comparedto that of the steel stud. In the case of the steel specimen with a thickness of 1.2mm, on the other hand, the average increase was 1.46times. All specimens showed full composite action until the collapse.