Bum-Yean Cho

Experimental Study of the Fire Behavior of CFT Columns in Relation to the Sectional Shape & Size

In this study, fire resistance tests were conducted to evaluate the fire resistance performance of unprotected and non-welded CFT columns in relation to the shape and size of cross-sections. Unprotected slot-type CFT columns which were □300 and □500 in dimensions resisted fire for 125 minutes and more than 180 minutes, respectively. Strain analysis showed that slot-type CFT columns were more ductile than welded CFT columns. The temperatures of central parts measured when welded CFT columns and slot-type CFT columns had lost fire resistance performance were higher in the former than the latter. Therefore, slot connection does not a great influence on the temperatures inside the concrete.

An Evaluation on Fire Resistance Performances of CFT Columns According to Conditions Exposed to Fire

CFT 기둥은 강재튜브 내에 콘크리트를 타설한 부재로서, 강재튜브에 의한 구속력으로 인하여 내부 콘크리트의 강도증 진 효과가 발휘되며, 별도의 철근보강 없이도 우수한 구조적 성능을 가지기 때문에 국내-외의 대형 건축물에 널리 사용되 고 있다. CFT 기둥은 강재튜브가 외부로 노출되어 있기 때문 에 필요한 내화성능을 확보하기 위해서는 일반적으로 적절한 내화처리가 필요하다. 그러나, 내화도료 또는 뿜칠 등의 시공 이 CFT기둥의 경제성을 저감시키기 때문에 무피복 CFT기둥 의 적용을 위하여 이에 대한 다양한 연구가 진행되어 왔다 (Lie, and Chabot, 1992; Chabot, and Lie, 1992; Wang, 2002; Kodur, 1999). 국내에서도 Ahn, and Lee, 2014 및 Choi et al., 2014에 의하여 무피복 각형 CFT기둥에 대한 실험적 연구 가 수행되었다. 이때, 모든 실험체는 4면이 모두 화재에 노출 된 조건으로 수행되었으며, 표준화재곡선(ISO 834, 1999; KS Abstract

An Experimental Study on the Temperature Behavior Characteristics of the Concrete Segment

As the plan to subsea tunnels was announced in Korea, how to secure fire-resistance of the concrete linings in shield tunnels has been emerging as an important issue. Reinforced concrete segment used inside of shield tunnels is structural member which resists loads such as earth pressure or hydraulic pressure. Since high-strength concrete having compressive strength of over 40 MPa is used, significant damage to the segment is foreseeable upon a fire unless elaborate measures are taken against a fire. Therefore, in this study to find how to improve safety of concrete structure in shield tunnels, damage range observed from full-scale fire resistance test was compared with that observed from fire resistance test provided by the EFNARC (European Federation for Specialist Construction Chemicals and Concrete Systems) and the behaviors of concrete linings in the fire tests were evaluated.

Experimental Study on Fire Resistance Performance of a Hollow Slab Using a Lightweight Hollow Sphere

This study evaluates the fire resistance performance (1–2h) of a reinforced concrete (RC) structure-void slab using a lightweight hollow sphere, which can reduce the unnecessary dynamic of removing the central concrete. For this experiment, we set up the depth of the concrete cover, live load, and span length as the factors. The result comes out with 50 mm cover depth of the RC structure hollow slab secured. It was shown that 120 minutes of fire resistance performance can be secured regardless of the length of the structure and loading. Among these factors, the resisting capability changes more sensitively with the live load rather than the thickness of cover. The shorter span in length could assure better fire resistance performance.

Experimental Study on the Fire Resistance Performance of Prestressed Composite Beam with Corrugated Web under Standard Fire with Loading Condition

In this study, fire resistance tests were performed on a conventional slim floor beam and a prestressed composite beam with corrugated webs, which is suitable for a long-span structure with a reduction in story height by utilizing the prestress and accordion effect. In the fire test program, the ISO 834 standard fire curve was adopted. Key test variables were the effect of prestress, shape of corrugated webs, and thickness of sprayed fireproofing material. All of the test specimens demonstrated enhanced fire resistance performance exceeding the expected performance level. The prestressed composite beams with corrugated webs especially showed excellent fire performance, considering these specimens had thin fireproofing thickness compared to the conventional slim floor specimen.

The Study on Fire Safety by a Real-Scale Combustion Experiment of Composite Material

In this study, a real-scale combustion experiment was carried out for a Styrofoam and glass wool sandwich panel to figure out the fire safety for the composite material used for a building. In the experiment, a heat release rate of a sandwich panel was measured by the ISO 9705 fire test method. Research has also tested and compared temperature change in the Large Scale Calorimeter (LSC) experiment equipment to evaluate the structural safety of the structure body. As a result of the experiment, the structural body with the Styrofoam sandwich panel collapsed which was caused by propagation, and in case of the glass wool sandwich panel, the combustion did no propagate inside. Since the composite material experiences various types of fire hazards depending on the combustion characteristics of the core material, the exact combustion characteristic should be expected by the full-scale combustion experiment.

Experimental Study for Fire Behavior and Heat Transfer Properties for Types of Fire Protection Method for 60 MPa High-Strength Concrete Column

In this study, we intend to propose a method for improving fire resistance performance by adding Fiber-Cocktail made by hybridizing steel fiber and Polypropylene fiber as the materials for reducing explosion to enhance the fire resistance performance of high-strength concrete and the effect on the fire resistance performance under standard fire loading conditions, in case of applying pre-stressed wire rope to 60 MPa high-strength reinforced concrete column. According to the test result, in case of applying hoops, the fire performance for 147 minutes has been secured and the wire-rope for 180 minutes. However, it was shown that the temperature of the main reinforcement exceeded in average, at maximum specified in the notices related to fire resistance performance of high strength concrete. However, in case of applying both of wire-rope and fiber-cocktail, it was shown that the fire performance for more than 180 minutes has been secured.

Experimental Study for Improving Method of Load Bearing and Spalling Prevention of 100 MPa High Strength Concrete Column

본 연구는 100 MPa급 고강도 콘크리트 기둥에 대하여 횡구속력 보강 및 내화보강 공법 적용 유무에 따른 내화성능을평가하기 위하여 표준화재 재하조건에서 내화실험을 실시하였다. 실험결과, 띠철근을 적용한 실험체의 경우 43분의 내화성능을 만족하여 내화구조로써 적용할 수 없는 것으로 나타났으며, 동일체적비로 띠철근을 대체한 와이어로프를 적용할경우 별도의 내화처리 없이 69분의 내화성능을 만족하여 4층 이하 건물에 적용할 수 있는 것으로 나타났다. 또한 띠철근을 대체한 와이어로프 및 폭렬방지를 위한 Fiber-Cocktail 혼입공법을 혼합 적용 할 경우 180분의 내화성능을 만족하여 12층 초과 건물에 적용할 수 있는 것으로 나타났다.ABSTRACTIn this study, we have conducted a fire resistance experiment under loading condition on standard fire to evaluate thefire resistance performance according to applying reinforcement of methods for reinforcing the lateral confinement ofreinforced bars (Wire Rope) and fire resistance reinforcement (Fiber-Cocktail) for 100 MPa high strength concrete col-umn. In the result of the experiment, in case of the test objects applied by hoop, it has been shown as not possible to beapplied as the fire resistance structure after satisfying the fire resistance performance for 43 minutes. In case of applyingthe wire rope as lateral confinement of reinforced bar, instead of hoop in identical volume ratio, it has been shown as pos-sible to apply it to the buildings with under 4 floors after satisfying the fire resistance performance fro 69 minutes withany separate fire resistance process. Also, in case of applying with mixing wire rope method, instead of hoop, and Fiber-Cocktail mix method to prevent spall, it has been shown as possible to apply to the buildings with over 12 floors after sat-isfying the fire resistance performance for 180 minutes.

A Study on the Fire Resistance Performance Concerning Types of Fire Protection Method and Load Ratio of High Strength Concrete Column Using The Wire Rope

The fire resistance test has been conducted under the standard fire & loading conditions to evaluate fire resistance performance, according to applying to methods of the lateral confinement reinforcement by prestressed Wire Rope and fire resistance reinforcement by Fiber-Cocktail and load ratio for high strength concrete column. The test result, for 60 MPa high-strength concrete column, It was indicated that applying to the wire rope has improved axial ductility in the fire condition, and fire resistance performance has been enhanced by more than 23 %. In addition to this, in case of applying the wire rope to 60 MPa high-strength concrete column, load can be judged that about 70 % of designed load is appropriate. If the Wire Rope and Fiber-Cocktail is applied to 100 MPa high-strength concrete column, It was shown that the fire resistance performance was enhanced by 4 times as much as applying only hoops.