• International Journal of Concrete Structures and Materials
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• v.6 no.4
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• pp.209-220
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• 2012

Post-earthquake fire (PEF) can lead to a rapid collapse of buildings that have been partially damaged as a result of a prior earthquake. Almost all standards and codes for the design of structures against earthquake ignore the risk of PEF, and thus buildings designed using those codes could be too weak when subjected to a fire after an earthquake. An investigation based on sequential analysis inspired by FEMA356 is performed here on the immediate occupancy (IO), life safety (LS) and collapse prevention (CP) performance levels of two portal frames, after they are pushed to arrive at a certain level of displacement corresponding to the mentioned performance level. This investigation is followed by a fire analysis of the damaged frames, examining the time taken for the damaged frames to collapse. As a point of reference, a fire analysis is also performed for undamaged frames and before the occurrence of earthquake. The results indicate that while there is minor difference between the fire resistances of the fire-alone situation and the frames pushed to the IO level of performance, a notable difference is observed between the fire-alone analysis and the frames pushed to arrive at LS and CP levels of performance and exposed to PEF. The results also show that exposing only the beams to fire results in a higher decline of the fire resistance, compared to exposing only the columns to fire. Furthermore, the results show that the frames pushed to arrive at LS and CP levels of performance collapse in a global collapse mode laterally, whereas at the IO level of performance and fire-alone situation, the collapse mechanism is mostly local through the collapse of beams. Whilst the investigation is conducted for a certain class of portal frames, the results confirm the need for the incorporation of PEF into the process of analysis and design, and provide some quantitative measures on the level of associated effects.

• Computers and Concrete
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• v.23 no.4
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• pp.281-294
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• 2019

The post-fire behavior of structural elements and the cooling process has always been one of the main concerns of the structural engineers. The structures can be cooled at different rates, where they affect the structure's behavior. In the present study, a numerical model has been developed using the Abaqus program to investigate the effect of cooling rate on the post-fire behavior of the CFST column. To verify the model, results of an experimental study performed on CFST columns within a full heating and cooling cycle have been used. In this model, coMParison of the residual strength has been employed in order to examine the behavior of CFST column under different cooling rates. Furthermore, a parametric study was carried out on the strength of steel and concrete, the height of the specimens, the axial load ratio and the cross-sectional shape of the specimen through the proposed model. It was observed that the cooling rate affects the behavior of the column after the fire, and thus the higher the specimen's temperature is, the more effect it has on the behavior. It was also noticed that water cooling had slightly more residual strength than natural cooling. Furthermore, it was recognized from the parametric study, that by increasing the strength of steel and concrete and the load ratio, as well as modifying the cross-sectional shape from circular to square, residual strength of column at the cooling phase was less than that of the heating phase. In addition, with reducing column height, no change was witnessed in the column behavior after the cooling phase.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.8
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• pp.139-148
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• 2019

The lightweight structures such as domes are particularly vulnerable when it has been subjected to high temperature induced by the fire. It is therefore crucial to predict the possible instability path of structures exposed to the fire in structural design process. In this study, the instabilities of single-layer domes is investigated by using finite element technologies with the consideration of high temperature. The material properties of members under high temperature are considered by using the reduction factors which is provided in Eurocodes 3. Some damage patterns are assumed with use of a structural unit which is symmetric in radial direction. For numerical evaluations, the geometrically nonlinear truss element is implemented and the arch-length control method is employed to trace the post-buckling behaviour of domes. From numerical results, it is found to be that a significant change of post-buckling behaviour is detected in dome structures when structural members are exposed to the fire.

• Fire Science and Engineering
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• v.30 no.4
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• pp.20-26
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• 2016

When the fire takes place in Nuclear Powr Plants(NPPs), the reactor should achieve and maintain safe shut-down conditions and minimize the radioactive material released to the environment. The U.S. Nuclear Regulatory Commission (NRC) has issued numerous generic communications related to fire protection over the past 20 years, after it issued its requirements in the Fire Protection Rule set forth in Title 10, Section 50.48 of the Code of Federal Regulations (10 CFR 50.48) and Appendix R to the 10 CFR 50. The and Nuclear Energy Institute (NEI) has developed a Methodology for Risk Informed Fire Safe-Shutdown Analysis, which is related to the Deterministic Method for Multiple Spurious Operations solutions. The aim of this study was to identify, achieve, and maintain Post-Fire Safe-Shutdown of the Main Control Room (MCR) of the CANDU reactor, even though one train of the multiple Safety Structures, Systems, and Components (SCCs) fail by the technical specification and analysis method.

• Fire Science and Engineering
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• v.32 no.1
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• pp.57-65
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• 2018

In this study, a post-fire safe shutdown analysis (PFSSA) including multiple spurious operation (MSO) treatments for cables was conducted with an imaginary nuclear power plant for training using a deterministic fire analysis code. The imaginary nuclear power plant for the training consisted of a reactor containment building and an auxiliary building, including a total of 22 fire areas. The equipment including valves, pumps, emergency diesel generators, switch gears, motor control centers, and logic controllers were located in each fire area of the imaginary plant. It was assumed that each equipment is connected with two cables and that each cable passes through the fire areas along the cable trays. A database containing the information on the equipment and cables for the imaginary plant was constructed for the fire area analysis. The fire area analysis was performed for several assumed MSO scenarios, equipment logics, and cable logics. A mitigation measure using a three hour rated wrap was applied to the failed cables and cable trays after the fire area analysis.

• Steel and Composite Structures
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• v.38 no.1
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• pp.87-102
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• 2021

To investigate the failure form, bending stiffness, and residual bearing capacity of monolithic composite beams with laminated slab throughout the fire process, fire tests of four monolithic composite beams with laminated slab were performed under constant load and temperature increase. Different factors such as post-pouring layer thickness, lap length of the prefabricated bottom slab, and stud spacing were considered in the fire test. The test results demonstrate that, under the same fire time and external load, the post-pouring layer thickness and stud spacing are important parameters that affect the fire resistance of monolithic composite beams with laminated slab. Similarly, the post-pouring layer thickness and stud spacing are the predominant factors affecting the bending stiffness of monolithic composite beams with laminated slab after fire exposure. The failure forms of monolithic composite beams with laminated slab after the fire are approximately the same as those at room temperature. In both cases, the beams underwent bending failure. However, after exposure to the high-temperature fire, cracks appeared earlier in the monolithic composite beams with laminated slab, and both the residual bearing capacity and bending stiffness were reduced by varying degrees. In this test, the bending bearing capacity and ductility of monolithic composite beams with laminated slab after fire exposure were reduced by 23.3% and 55.4%, respectively, compared with those tested at room temperature. Calculation methods for the residual bearing capacity and bending stiffness of monolithic composite beams with laminated slab in and after the fire are proposed, which demonstrated good accuracy.

• Journal of Aerospace System Engineering
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• v.5 no.1
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• pp.7-12
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• 2011

The goal of fire prevention research is to eliminate fires as a cause of fatal accidents and there are two main areas of research. One is to prevent flame propagation during in-flight and it addresses fire hazards. The other is to minimize the possibility of flame penetration or fuselage burn-through and it aims toward post-crash survival include crash protection, emergency evacuation and post-evacuation survival. Civil aviation authorities world-wide are trying to identify threats and measure performance for fire prevention. The results of research are standardized and given as general directions of test methods. This paper has prepared to study and present the means of compliance to the fire prevention requirements and applicable test methods.

• Steel and Composite Structures
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• v.30 no.4
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• pp.351-364
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• 2019

Earthquake and fire are both severe disasters for building structures. Since earthquake-induced damage will weaken the structure and reduce its fire endurance, it is important to investigate the behavior of structure subjected to post-earthquake fire. In this paper, steel-concrete composite beam-to-column joints were tested under fire with pre-damage caused by cyclic loads. Beforehand, three control specimens with no pre-damage were tested to capture the static, cyclic and fire-resistant performance of intact joints. Experimental data including strain, deflection and temperature recorded at several points are presented and analyzed to quantify the influence of cyclic damage on fire resistance. It is indicated that the fire endurance of damaged joints decreased with the increase of damage level, mainly due to faster heating-up rate after cyclic damage. However, cracks induced by cyclic loading in concrete are found to mitigate the concrete spalling at elevated temperatures. Moreover, the relationship between fire resistance and damage degree is revealed from experimental results, which can be applied in fire safety design and is worthwhile for further research.

• Fire Science and Engineering
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• v.32 no.2
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• pp.92-101
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• 2018

This study investigated the impact of post-traumatic stress of the fire-fighting officers who are exposed to traumatic events repeatedly on suicide and attempted to verify the moderating effect of cognitive emotion regulation in the relationship between post-traumatic stress and suicidal ideation. For this investigation, this study measured Post-traumatic stress Diagnostic Scale, Korean Beck scale for Suicidal Ideation, Cognitive Emotion Regulation Questionnaire. The research results are as follows. First, Post-traumatic stress, suicidal ideation, adaptive cognitive emotion regulation, and maladaptive cognitive emotion regulation were correlated. second, A hierarchical regression analysis was conducted in order to examine the moderating effect of cognitive emotion regulation in the relationship between post-traumatic stress and suicidal ideation, and as a result, it was found that a sub-factor of cognitive emotion regulation, adaptive cognitive emotion regulation had a moderating effect in a group of persons with low post-traumatic stress, while maladaptive cognitive emotion regulation had a moderating effect in a group of persons with high post-traumatic stress. These results, this study discussed the necessity of follow-up studies, in addition to its academic and clinical implications.

• Steel and Composite Structures
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• v.5 no.2_3
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• pp.193-202
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• 2005

This paper describes recent developments in composite construction and their effect on codified design procedures in the UK. Areas of particular interest include: rules on shear connection, design of beams with web openings, serviceability limits, such as floor vibrations, and fire safe design. The design of cellular beams with regular circular openings now includes generalized rules for web-post buckling, and for the development of in-plane moment in the web-post for asymmetric sections. Closed solutions for the maximum shear force due to limits on web-post bending or buckling are presented. The fire resistance of cellular beams is also dependent on the temperature of the web-post, and for closely spaced openings. It is necessary to increase the thickness of fire protection to the web. For serviceability design of beams, deflection limits and natural frequency and response factor for vibration are presented. It may be necessary to use stricter limits for certain applications.