• Elastomers and Composites
• /
• v.50 no.4
• /
• pp.279-285
• /
• 2015

This study examined the mechanical properties and the flame retardant properties of CR rubber containing inorganic flame retardant with various contents of aluminium trihydroxide (ATH, $Al(OH)_3$). The content of aluminium trihydroxide was added in 0, 30, 50, 70 and 100 phr for T1~T5 samples. It was found that increasing the amount of addition over 30 phr resulted in decreasing the mechanical properties. On the other hand in oxygen index measurements T1 sample showed a value of 38.6%, indicating the improvement of flame retardant properties showed a value of 49.7~64.2%. In case of burn test, it was confirmed that CR rubber containing over ATH 50phr content showed performance corresponding to that of first grade fire-resistance.

• Computers and Concrete
• /
• v.18 no.6
• /
• pp.1097-1112
• /
• 2016

Fire loading causes a critical collapse of RC (Reinforced Concrete) Structures since the embedded steels inside are relative week against high elevated temperature. Several numerical frameworks for fire resistance have been proposed, however they have limitations such as unstable convergence and long calculation period. In the work, 2-D nonlinear FE technique is proposed using Galerkin method for RC structures under fire loading. Closed-form element stiffness with a triangular element is adopted and verified with fire test on three RC slabs with different fire loading conditions. Several simulations are also performed considering fire loading conditions, water contents, and cover depth. The proposed numerical technique can handle time-dependent fire loading, convection, radiation, and material properties. The proposed technique can be improved through early-aged concrete behavior like moisture transport which varies with external temperature.

• Journal of the Korea Concrete Institute
• /
• v.22 no.2
• /
• pp.229-235
• /
• 2010

In this study, fire resistance performance of high strength concrete specimen with fireproof gypsum board was investigated for possible use in upgrading fire-resistant performance of the existing building and repair of fire damaged structures. Fire test of eight identical high strength concrete columns were carried out for 180 minutes in accordance with ISO-834. The temperature distributions in longitudinal reinforcement and concrete temperature at various depths were recorded. The fireproof performance of gypsum board and explosive spalling of concrete were observed. The specimens with 15 mm thick twoply fireproof gypsum board spalled after gypsum board crumbled regardless of fastening methods. However, when the thickness of fireproof gypsum board was more than 30 mm, it was possible to prevent the explosive spalling and control the rebar temperature. Although the effect of cover thickness could not be compared because the explosive spalling occurred, there seemed to be no difference in insulation efficiency.

• Steel and Composite Structures
• /
• v.46 no.3
• /
• pp.345-352
• /
• 2023

A thermal-mechanical coupling finite element model of the steel-plate concrete composite (SC) wall is established, taking into account the strain rate effect and variation in mechanical and thermal properties under different temperatures. Verifications of the model against previous fire test and impact test results are carried out. The impact response of the SC wall under elevated temperatures is further investigated. The influences of the fire exposure time on the impact force and displacement histories are discussed. The results show that as the fire exposure time increases, the deflection increases and the impact resistance decreases. A formula is proposed to calculate the reduction of the allowable impact energy considering the fire exposure time.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.557-562
• /
• 2002

This paper describes the results of spalling by fire prevention of high performance concrete confining with metal-lath and containing PP fiber. According to test results, all the specimens without PP fiber shows entire failure after exposed to fire, while the other specimens confined with metal-lath has somewhat better spatting prevention performance than plain concrete specimens, which only show surface scale spatting combination of PP fiber with confinement of metal-lath leads to favorable spatting resistance. As PP fiber contents and thickness of metal-lath which is confined at concrete specimens increase, residual strength after exposed to fire shows to be increased.

• Journal of Advanced Engineering and Technology
• /
• v.11 no.4
• /
• pp.279-285
• /
• 2018

A shear connection between the steel beam and concrete slab determines the stability of composite beams. An extensive numerical study to evaluate the resistance of the shear connection in a solid slab at high temperature was conducted. Three-dimensional thermo-mechanical finite element models were developed using a dynamic explicit method and concrete damaged plasticity model. Temperature-dependent plasticity parameters of the concrete model were proposed, and the accuracy of the developed model was obtained against experimental data. This investigation has revealed that a stud shearing failure occurs regardless of temperatures, and its shearing location changes in accordance with a rise in temperature. A new strength reduction formula has been presented to estimate the resistance of the shear connection at high temperatures.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.3
• /
• pp.33-41
• /
• 2016

Concrete is inherently a good fire-resistance material among all other constrcution materials and protects the reinforcing steel inside. This study investigates the material characteristics of concrete and steel bar inside the full scale reinforced concrete(RC) beam exposed to fire test. The fire test specimen was 4 m long and the test was conducted under no loading condition following KS F 2257. Fire source is simulated by ISO 834 and number of thermocouples were installed to measure temperature variation of surfaces and inside of the beam. The measured compressive strength of cored specimen, which was exposed to fire test, was 11 MPa, about 66% lower than the strength before exposure. The yielding strength of steel bar also decreased about 75 MPa, about 17% lower. The measured temperature of protected steel bar was around $649^{\circ}C$, the critical limit, after 4 hour exposure.

• Journal of the Korean Society of Safety
• /
• v.30 no.4
• /
• pp.26-31
• /
• 2015

The purpose of this paper is to measure the induced voltage of the downscaled and simulated overhead ground wire of a 22.9kV-Y distribution line. This study performed a test of the downscaled and simulated distribution line according to whether it is grounded or not and the value of the ground resistance. In order to verify the reliability of the data measured by the test, the data was analyzed using the Minitab 17 program. It was found that the induced voltage of the downscaled and simulated distribution line is influenced by the value of the ground resistance. It was also found that the ground resistance obtained at a certain point is closely related to whether electric poles are grounded or not. The analysis results of the measured test data with a statistical method showed that the Anderson Darling (AD) was analyzed to be the smallest as 0.188 when the ground resistance of the electric poles had been maintained at $10{\Omega}$. In addition, the P value analyzed to be 0.894 which is in the proximity of the theoretical value of 1 and verified the reliability of the test data. It could be seen that the data measured by the downscaled simulation test forms a linear graph. It is thought that if a distribution line is installed in the same manner as the downscaled, simulated distribution line, the mean induced voltage will be reduced and reliability will be increased.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.22 no.6
• /
• pp.669-680
• /
• 2020

In Korea, fireproof performance is evaluated through a series of fire-resistance tests for important structures, and the performance standard follows the guidelines suggested by ITA. The fireproof duct slab manufactured by combining the slab and the fireproof material with a precast method is effective in that it can eliminate the construction time of the fireproof material. In this study, a series of fire resistance tests was performed on the fire test specimens under the RWS fire scenario in order to secure the fire resistance performance of the precast fireproof duct slab. As a result of the test, it was found that the fireproof performance was secured when the thickness of the fireproof material was 30 mm or more. In both fireproof materials and concrete, the rate of temperature change initially increased, then decreased, and then increased again, and the temperature at the inflection point was measured as 110℃ for all fireproof materials and concrete. It is judged that this occurs when the C-S-H (CaO-SiO₂-H₂O) generated by the hydration reaction in both the fireproof material and concrete is dehydrated.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.537-540
• /
• 2008

Tunnel structures are constructed even longer and more extensive these days than they were in the past. Because of this reason, breaking out a large scale of fire in tunnel structures is frequently. Recently, a noticeable event is reported that the temperature of inside of tunnel rises significantly when an oil car detonated in the tunnel and it reached 1,350$^{\circ}$C. It did damage to people who used the tunnel at that time and caused many demaged parts of tunnel to recover. To improve a fire resistance of tunnel, many methods are studied focused refractory concrete and mortar. This study deals with refractory mortar and is a part of initial basic step. In this study mechanical properties are considered before fire resistance test. As result of test for examination of mechanical properties, it is considered that a consistency and strength of refractory mortar in this study are suitable to construct.