• International journal of steel structures
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• v.18 no.5
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• pp.1497-1507
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• 2018

Most of previous studies on fire resistance of restrained steel beams neglected creep effect due to lack of suitable creep model. This paper presents a finite element model (FEM) for accessing the fire resistance of restrained high strength Q460 steel beams by taking high temperature Norton creep model of steel into consideration. The validation of the established model is verified by comparing the axial force and deflection of restrained beams obtained by finite element analysis with test results. In order to explore the creep effect on fire response of restrained Q460 steel beams, the thermal axial force and deflection of the beams are also analyzed excluding creep effect. Results from comparison infer that creep plays a crucial role in fire response of restrained steel beam and neglecting the effect of creep may lead to unsafe design. A set of parametric studies are accomplished by using the calibrated FEM to evaluate the governed factors influencing fire response of restrained Q460 steel beams. The parametric studies indicate that load level, rotational restraint stiffness, span-depth ratio, heating rate and temperature distribution pattern are key factors in determining fire resistance of restrained Q460 steel beam. A simplified design approach to determine the moment capacity of restrained Q460 steel beams is proposed based on the parametric studies by considering creep effect.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.377-384
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• 2011

Although concrete is considered as fire proof materials, high strength concrete shows severe material and structural damages when exposed to fire. To understand such damages in high strength concrete structures, the effects of various design parameters and fire condition on the thermal behaviors of high strength concrete structures are investigated in this study. In order to achieve this goal, fire tests are performed on high strength concrete columns with different fire conditions and design parameters including cross sectional area, cover thickness, and reinforcement alignment. To investigate thermal behaviors, temperature distributions and amount of spalling are measured. In overall, the columns show rapidly increasing inner temperatures between 30~60 mins of the fire tests due to spalling. In detail, the higher temperature distributions are observed from the columns with the larger cross section and less cover thickness. Moreover, among the columns with same reinforcing ratio, larger number of reinforcements with the smaller diameter causes the higher temperature distribution. The findings from the experimental study allow not only understanding of thermal behaviors of high strength concrete columns under fire, but also guidance in revising fire safety design.

• Steel and Composite Structures
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• v.13 no.4
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• pp.309-325
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• 2012

The risk of progressive collapse in steel framed buildings under fire conditions is gradually rising due to the increasing use of combustible materials. The fire resistance of such steel framed buildings is evaluated by fire tests. Recently, the application of performance based fire engineering makes it easier to evaluate the fire resistance owing to various engineering techniques and fire science. The fire resistance of steel structural members can be evaluated by the comparison of the limiting temperatures and maximum temperatures of structural steel members. The limiting temperature is derived at the moment that the failure of structural member results from the rise in temperature and the maximum temperature is calculated by using a heat transfer analysis. To obtain the limiting temperatures for structural steel of grades SS400 and SM490 in Korea, tensile strength tests of coupons at high temperature were conducted. The limiting temperatures obtained by the tensile coupon tests were compared with the limiting temperatures reported in the literature and the results of column fire tests under four types of loading with different load ratios. Simple limiting temperature formulas for SS400 and SM490 steel based on the fire tests of the tensile coupons are proposed. The limiting temperature predictions using the proposed formulas were proven to be conservative in comparison with those obtained from H-section and hollow section column fire tests.

• Fire Science and Engineering
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• v.22 no.4
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• pp.85-94
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• 2008

The purpose of this study is to obtain the fundamental fire resistance performance of engineered cementitious composites (ECC) under fire temperature in order to use the fire protection material in high-strength concrete structures. The present study conducted the experiment to simulate fire temperature by employing of ECC and investigated experimentally the explosion and cracks in heated surface of these ECC. In the experimental studies, 5 HSC specimens are being exposed to fire, in order to exami ne the influence of vari ous parameters (such as depth of layer=20, 30, 40 mm; construction method=lining and repairing type) on the fire performance of HSC structures. Employed temperature curve were ISO 834 criterion (3 hr), which are severe in various criterion of fire temperature in building structures. The numerical regressive analysis and proposed equation to calculate ambient temperature distribution is carried out and verified against the experimental data. By the use of proposed equation, the HSC members subjected to fire loads were designed and discussed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.19-22
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• 2007

This study discussed the prevention of the spalling and improvement of the fire resistance performance how to fill up lightweight foamed concrete on high strength RC column attached with the stone panel. The destructive spalling extremely occur caused by sudden high temperature and increased vapor pressure corresponding to falling the ston panel at all RC column, and the steel bar is exposed. The stone panel fall off about 30 minutes and spalling occur about 70 minutes on Plan RC column, fire endurance paint, and fire endurance mortar, so it can be confirmed that fire endurance paint and mortar, which is used as fire endurance material, are not effective. In the other side, it can be protected from fire about $120{\sim}140$ minutes when the lightweight foamed concrete is used as fire endurance material. For the weight loss after the fire test, plain is 33, fire endurance paint is 37%, and fire endurance mortar s 40.7%. And W/B 60%-3 is 53.4%, 60%-1.5 is 40.1%,65%-3 is 39.4%, and 65%-1.5% is 47.1. Overall, the weight loss of the plain is lower than that of the lightweight foamed concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4C
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• pp.265-273
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• 2006

This study aims at evaluation of the fire resistance performance of cementitious materials for fire protection of tunnel. For this purpose, the research procedure was divided into three parts. First, base mix proportion with different material type were determined by fire test. Second, the fire test of cementitious materials for fire resistance were performed on base mix proportions to evaluated their performance. Third, the performance of cementitious materials for fire resistance compare to the target value and existing commercial products. If the performance of developed cemetitious materials for fire resistance were satisfied the target value, this studies were stopped. But, this research return to first process if the performance of cementitious materials for fire resistance are not satisfied the target value. As a result of this study, the spalling did not happen for develop and existing commercial product. Also, developed cementitious materials for fire resistance are shown with excellent compressive strength, flexural strength, and bond strength, because it used a height density aggregate. And developed cementitious materials has sufficient resistance for fire.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.33-36
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• 2006

The purpose of this paper is to investigate the structural behavior of fire damaged high-strength SRC columns with polypropylene fiber. When high-strength concrete is exposed to high temperature, spalling is occurred then it leads to decrease the capacity of members. Polypropylene fiber is used to reduce the spalling of the specimens and the distinction in the behavior after fire is observed. High-strength concrete specimens were exposed to high temperatures by the ISO 834 curve. Main experimental parameters were the ratio of the contained polypropylene fiver, heating time and type of loading. Reduction rate in residual strength and stiffness is observed for the mixing of PP fiber, the heating time and eccentricity of loading.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.161-168
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• 2004

This study describes the behavior and failure probability of basic structural member in case of fire for the research of safety assessment on onshore structure. Fire safety assessment can be done by comparing fire resistance of members with fire severity of heat load For more Practical applications, the commercial structural analysis program is linked with the in-house code and gets the limiting temperature by analyzing structural strength of member with elasto-plastic analysis and large deflection analysis. AFOSM method is utilized to obtain the failure probability against the fire. The examples of rather simple structures such as beams and plates are applied to explain and verify the procedure of fire safety assessment.

• Fire Science and Engineering
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• v.1 no.1
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• pp.19-26
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• 1987

In this study, fire resistance of steel fiber reinforced concrete was investigated Cylindrical and prismatic specimens made of Ordinary Portland Cement plain concrete and steel fiber reinforced concrete were exposed to heating in accordance with a standard time-temperature curve as specified in KS·F22 57, method of fire resistance test for structural parts of buildings, the period of heating was 1 hour and 2 hours. After the fire resistance test, mechanical properties of specimens such as compressive and bending strength, stress-strain curve, static and dynamic modulus of elasticity and bending toughness were investigated. Also the cracks and spallings of the specimens were observed. From the test results, it was confirmed that steel fiber reinforced concrete has a excellent fire resistance than plain concrete in the view of higher residual strength of concrete and smaller crackings because of steel fibers in concrete.

• Journal of Korean Association for Spatial Structures
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• v.15 no.3
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• pp.95-102
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• 2015

Numerical model on precast prestressed concrete (PC) hollowcore slabs using 11.3 mm diameter 7-wire stand was developed based on finite element analysis. In order to validate the modelling, previous experiment results with respect to prestressed solid concrete slabs were used and compared throughout the course of fire exposure. In addition to, the fire performance of hollowcore slabs with different aggregate types, moisture contents and compressive strength of concrete was investigated. As a result, it can be seen that the type of aggregates and moisture contents used in hollowcore slabs can affect the fire performance as well as temperature developments.