• Journal of the Korean Society of Hazard Mitigation
• /
• v.6 no.1 s.20
• /
• pp.17-27
• /
• 2006

To estimate the retained strength of reinforced concrete structure after fire is very difficult because the complex behavior of structure is hard to understand during course of a fire. However, the damages which is caused by fire of the traffic facility infrastructure are enormous. Therefore the security against fire is important element that must not be overlooked. For this reason, an exact estimate method of the fire endurance is highly demanded. In this study, the validity of the nonlinear finite element method approach for the fire endurance of reinforced concrete structure is verified. The results of fire endurance estimate of underground road way by nonlinear finite element method approach are compared with those by ACI 216R-89.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.487-488
• /
• 2010

This is the experimental and analysis study on the thermal distribution, structural behavior and residual strength of high strength concrete members subjected to fire. The parameters are strength of concrete, cover thickness, loading state and exposure time to fire. The ISO 834 standard fire curve is used to test. The material and structural property of concrete at high temperature are proposed, also.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.1
• /
• pp.190-196
• /
• 2006

In the existed study, a fire outbreak in a reinforced concrete structure looses the organism by the different contraction and expansion of hardened cement pastes and aggregate, and causes cracks by thermal stress, leading to the deterioration of the durability. So 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. Therefore, This study is willing to propose fundamental data for quick and accurate diagnosis of deteriorated concrete structure by fire damage with making variable concrete test specimen, exposing high temperature environment, observing the explosive spalling and examining engineering property.

• Journal of the Korea Concrete Institute
• /
• v.25 no.5
• /
• pp.497-508
• /
• 2013

This paper introduces a numerical model which can evaluate the fire-resistant capacity of reinforced concrete members. On the basis of the transient heat transfer considering the heat conduction, convection and radiation, time-dependent temperature distribution across a section is determined. A layered fiber section method is adopted to consider non-linear material properties depending on the temperature and varying with the position of a fiber. Furthermore, effects of non-mechanical strains of each fiber like thermal expansion, transient strain and creep strain are reflected on the non-linear structural analysis to take into account the extreme temperature variation induced by the fire. Analysis results by the numerical model are compared with experimental data from the standard fire tests to validate an exactness of the introduced numerical model. Also, time-dependent changes in the resisting capacities of reinforced concrete members exposed to fire are investigated through the analyses and, the resisting capacities evaluated are compared with those determined by the design code.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.1
• /
• pp.101-113
• /
• 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 Institute of Fire Science and Engineering Conference
• /
• 2011.04a
• /
• pp.89-93
• /
• 2011

본 연구는 고강도콘크리트의 폭렬성상과 공극구조와의 관계를 실험적으로 규명하는 것을 목적으로 하였다. 실험변수는 양생방법, 압축강도, 공극구조로 설정하였으며, ISO834 화재온도이력곡선을 15분 적용하여 콘크리트의 초기 폭렬특성을 실험적으로 검토하였다. 그 결과 50 MPa급 이상의 고강도 콘크리트 시험체의 경우, 가열 이후에도 $0.05{\mu}m$ 이하의 공극이 많이 존재하고 있는 것을 알 수 있었으며, 가열을 받은 고강도 콘크리트는 고강도화될수록 공극이 세공화 되어 탈수 현상이 지연되는 것을 도출 할 수 있었다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2011.11a
• /
• pp.382-385
• /
• 2011

본 논문은 초고강도콘크리트의 폭렬현상을 연구해 보고자 실리카흄 유무와 PP섬유의 혼입량을 변수로 하여 공시체와 벽체의 폭렬현상을 관찰한 후 변수가 초고강도콘크리트에 어떠한 영향을 주는지를 실험적으로 규명하는 것을 목적으로 하였다. KS F 2257 화재온도이력곡선을 30분 적용하여 콘크리트의 초기 폭렬특성을 실험적으로 검토하였다. 그 결과 공시체의 경우 압축강도가 100 MPa 초고강도콘크리트의 경우에는 실리카흄 여부와 PP섬유 혼입량이 폭렬억제에 관계되는 주요 인자인 것을 알 수 있었으며, 벽체의 경우에는 벽체 시험체의 부분 가열 및 전면 가열 실험을 실시했다. 폭렬 최대 깊이, 시간, 소리 발생 회수를 비교하면 부분 가열이 전체 가열에 비해 폭렬이 빠르고 깊게 발생하는 것으로 나타났다.

• Journal of the Korea Concrete Institute
• /
• v.29 no.3
• /
• pp.237-248
• /
• 2017

Frequent terror or military attack by explosion, impact, fire accidents have occurred recently. These attacks and incidents raised public concerns and anxiety of potential terrorist attacks on important infrastructures. However, structural behavioral researches on prestressed concrete (PSC) infrastructures such as Prestressed Concrete Containment Vessel (PCCV) and Liquefied Natural Gas (LNG) storage tanks under extreme loading are significantly lacking at this time. Also, researches on possible secondary fire scenarios after terror and bomb explosion has not been performed yet. Therefore, a study on PSC structural behavior from an blast-induced fire scenario was undertaken. To evaluate the blast-fire combined resistance capacity and its protective performance of bi-directional unbonded PSC member, blast-fire tests were carried out on $1,400mm{\times}1,000mm{\times}300mm$ PSC specimens. Blast loading tests were performed by the detonation of 25 kg ANFO explosive charge at 1.0 m standoff distance. Also, fire and blast-fire combined loading were tested using RABT fire loading curve. The test results are discussed in detail in the paper. The results can be used as basic research references for related research areas, which include protective design simulation under blast-fire combined loading.

• Fire Science and Engineering
• /
• v.23 no.3
• /
• pp.110-120
• /
• 2009

In tunnel, though the frequency of fire occurrence is relatively lower than other structures, the characteristics of sealed space tends to cause the temperature to rapidly rise to more than $1000^{\circ}C$ within 5minutes after fire, which might eventually lead to a large fire that usually results in a loss of lives and the damage to the properties, not to mention a huge cost necessary for repair and maintenance after fire. We have developed various conditions of the heating furnace and the method to install a thermo couple within the furnace based on EFNARC and KS F 2257-1. Referring to tunnel fire scenarios, it clarified the heat transfer characteristics of concrete PC panel lining depending on fire intensity (ISO, $1^{\circ}C$/SEC, MHC, RWS), and to identify the range of thermal damage, the evaluation was carried out using ITA standard. As a result, 30mm under ISO fire condition, 20mm under $1^{\circ}C$/SEC, 100mm under MHC and 50mm under RWS were measured. And when it comes to spalling, 30mm was measured under RWS and MHC.

• Fire Science and Engineering
• /
• v.22 no.2
• /
• pp.84-90
• /
• 2008

This paper aims to experimentally investigate the in-fire performance of composite beams with respect to the effects of load ratio and shear interaction. Under a Standard ISO834 fire, the development of temperature and deflection of simply supported composite beams were recorded. In particular, the transition of temperature distribution across the cross-section. The fire resistance of composite beam was interpreted regarding the level of shear interaction.