• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.101-113
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• 2015

This paper introduces a numerical analysis method for reinforced-concrete(RC) members exposed to fire and proposes considerations in designing RC structures on the basis of the comparison between numerical results and design codes. The proposed analysis method consists of two procedures of the transient heat transfer analysis and the non-linear structural analysis. To exactly evaluate the structural behavior under fire, two material models are considered in this paper. One is "Under-Fire" condition for the material properties at the high temperature and the other one is "After-Cooling" condition for the material properties after cooling down to air temperature. The proposed method is validated through the correlation study between experimental data and numerical results. In advance, the obtained results show that the material properties which are fittable to the corresponding temperature must be taken into account for an accurate prediction of the ultimate resisting capacity of RC members. Finally, comparison of the numerical results with the design code of EN1992-1-2 also shows that the design code needs to be revised to reserve the safety of the fire-damaged structural member.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.13-16
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• 2005

This study is aimed to investigate the strength variation of fire-damaged reinforced concrete column by non-destructive test. It is studied to infer the recovery degree of residual strength of fire-damaged concrete. For measuring the surface hardness of RC columns. Schmidt hammer test is used. Testing is performed three-times: before fire test, directly after fire test and after 20 days.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.16-18
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• 2013

A fire outbreak in a reinforcement concrete structure looses the organism by different contraction and expansion of hardened cement pastes and aggregate, and causes cracks by thermal stress, leading to the deterioration of the durability. So, concrete reinforcement structure is damaged partial or whole structure system. Therefore accurate diagnosis of deterioration is needed based on mechanism of fire deterioration in general concrete structures. Fundamental information and data on the properties of concrete exposed to high temperature are necessary for accurate diagnosis of deterioration. In this study, consider case of investigation methods and repair work in fire damaged structure concrete.

• Advances in concrete construction
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• v.6 no.2
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• pp.177-197
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• 2018

This paper presents a case study about the damages on the structural elements of a cast in place reinforced concrete (RC) building after a big fire which was able to be controlled after six hours. The fire broke off at the $2^{nd}$ basement floor of the building, which has five basements, one ground, and two normal floors. As a result of intensely stocked ignitable materials, it spread out to the all of the upstairs. In visual inspection, most of the typical fire damages were observed (such as spalling, net-like cracks, crumbled plasters, bared or visible reinforcement). Also, failures of the $2^{nd}$ basement columns were encountered. It has been concluded that the severity failures of the columns at the $2^{nd}$ basement caused utterly deformation of the building, which is responsible for the massive damages on the beam-column connections. All of the observed damages were categorized related to the types and presented separated regarding the floors. Besides to the visual inspection, the numerical analysis was run to verify the observed damaged on the building for columns, beams, and the connection regions. It is concluded from the study that several parameters such as duration of the fire, level of the temperature influence on the damages to the RC building. Also, it is highlighted by the study that if the damaged building is considered on the overall structural system, it is not able to satisfy the minimum service requirements neither gravity loads nor earthquake conditions.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.195-201
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• 2008

When reinforced concrete is subjected to high temperature as in fire, there is deterioration in its properties of particular importance are loss in compressive strength, cracking and spalling of concrete, destruction of the bond between the cement paste and the aggregates and the gradual deterioration of the hardend cement paste. Assessment of fire-damaged concrete usually starts with visual observation of color change, cracking and spalling of the surface. In this paper, it was reported the trends of research and practical use on the Explosive Spalling Properties of the High-Strength Concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.211-213
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• 2003

Evaluation of bond strength of a fire-damaged reinforced concrete structure for determining whether to reuse, reinforced, or abandon the structure is very important. Recently, calculating method for changes in bond strength of rebars is proposed by C. Chiang. The equation is relating the ratio of residual bond strength, R, to temperature, T, and exposure time, t. This study presented and verified a general process for evaluating damage to bond strength of RC structure arising from high temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.50-51
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• 2013

In case of Korea, it goes frequently that underground parks has been burned. Based on standard temperature time curve(ISO-834), gerber, walls, slab of structures are constructed. However, Standard temperature time Curve is not considered that buildings are affected by vehicle fire. that is why it has the hazard that makes building reinforcement feeble. Based on the result that got from vehicle experiment before, we made four RC slab in this experiment and set the fire severity. according to the loading experiment after heating, we measured the effects that makes reinforcement and shape changes. Furthermore, we examined the safty of the structure by comparing before and after heating.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.866-876
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• 2003

Experiments were performed for the real sized 12 reinforced concrete columns of 350${\times}$350${\times}$3350 mm with normal concrete in order to observe the fire-damaged behavior of these columns. Columns were heated according to the ISO heating curve. Main experimental parameters were: magnitude of axial load, heating time, cover thickness, and eccentricity. Effects of these parameters on the axial expansion and contraction, rotation, buckling, ISO fire resistance, and structural stability were experimentally quantified. It has been observed that the contraction rate of axial deformation was affected mostly by the duration of heating time and buckling of reinforcement or member by the magnitude of axial load, duration of heating time, cover thickness and eccentricity in order. Based on the experimental observations, ISO fire resistance criteria were qualiatively criticized.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.188-197
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• 2010

This paper presents research result to study the change of structural capacity of reinforced concrete beams with various shear reinforcement ratios after damage by fire load. In addition, fundamental data are given in order to predict the strength variation of RC member due to fire damage by evaluating the previous calculation method codified in codes. Nine RC beam specimens were made and exposed to the fire controled by the standard fire curve. And the structural capacity was evaluated through a failure test under simple support condition. Previous code formula, ACI code and Eurocode were reviewed and used for the calculation of the strength of specimens damaged by fire. From the test, RC beam specimens exhibited very brittle failure when it exposed to fire controled by standard fire curve during more than one hour. And this failure pattern tended to be more serious when shear reinforcement ratio decreased or fire loading duration increased. From the evaluation of the calculation process in code, the change of strength due to fire can be properly predicted if the damage of materials is well defined.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.257-260
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• 2008

This study will make P-M interaction diagram of residual capacity at fire-damaged High strength concrete column with polypropylene fiber. Evaluating capacity of column decreasing spalling with P-M interaction diagram is important. because high strength concrete column with polypropylene fiber isn't section area loss. P-M interaction diagram that is made to analyze according to a various parameters is useful index for design and evaluating capacity of columns. In this study, spalling, temperature distribution of interior column, residual strength and movement of column in eccentric loading are studied with expose time of high temperature. For study fire test that is similar real act, and after cooling in normal condition residual strength of specimen is estimated. And this study use DIANA(Displacement Analyzer) for analyzing nonlinear analysis. with experiment temperature and strength data.