Fire Resistance of Building Materials as a Basic Characteristic of Fire Resistance Kinetic Theory

Roytman, Vladimir; State, Moscow

doi:10.25257/fe.2019.1.62-69

Cited by 2 publications

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“…Overtime accumulation of damages in a sample during isothermal endurance under constant load is characterized by classical creep curves with three distinctive regions. Time before destruction (longevity of concrete) is described by the Boltzmann -Zhurkov kinetic equation [21].…”

Section: Figure 1 Graphical Interpretation Of the Principle Of Indepe...mentioning

confidence: 99%

Basic principles in the theory of force and thermal force resistance of concrete

Fedorov

Levitsky

Isaeva

2022

Struct. Mech. of Eng. Const. and Build

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In the development of the ideas and approaches to the analysis of the force resistance of concrete of V.M. Bondarenko, the initial prerequisites for the model of the thermomechanical state of concrete under short-term sharp high-temperature exposure, characteristic of fire conditions, are formulated. The separation of force deformations into components is carried out on the basis of the connection with the accumulation of damage in the structure of the material, based on the principle of independence of the limiting structural stresses from temperature and the mode of force action, which makes it possible to establish basic thermomechanical relationships and determine the deformation parameters of concrete operating under conditions of unsteady heating in a loaded state. Based on the extension of the hypothesis of entropy damping of nonequilibrium processes to the area of action of an active destructive factor, the principle of normalization was formulated and a kinetic equation was proposed, from the solution of which exponential dependences having a single structure were obtained, which make it possible to describe the basic temperature parameters of concrete, the relationship of stresses with deformations, and other nonlinear characteristics. The application of the proposed principles creates a reliable theoretical basis for describing the mechanisms of thermal resistance of concrete and greatly simplifies the modeling of the effect of high temperature on the properties of concrete in the practical implementation of methods for the numerical calculation of reinforced concrete structures.

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Section: Figure 1 Graphical Interpretation Of the Principle Of Indepe...mentioning

confidence: 99%

Basic principles in the theory of force and thermal force resistance of concrete

Fedorov

Levitsky

Isaeva

2022

Struct. Mech. of Eng. Const. and Build

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The research into the heating effect of secondary steel structures, having no fire proofing, on the fire resistance of fireproof steel beams

Vorosin

Parfenenko

2021

Požarovzryvobezopasnostʹ

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Introduction. The international practice of passive fire protection design, as well as some manufactures of fireproofing products recommend to apply fire proofing substances not only to the main element, whose fire resistance limit is standardized, but also to the elements that do not fall under any fire resistance standards. Various support brackets, pipeline supports (hereinafter — PS), etc. can serve as examples. They are not considered as bearing elements according to SP (Construction Regulations) 2.13130.2020, although they are connected to the structures that have fireproofing applied. It is recommended to apply fireproofing substances to such PS within the range of, at least, 450 mm from the point of attachment to the fireproof structure when the area of the PS cross section exceeds 3,000 mm2. No “supplementary” fireproofing is required by the Russian design and fire protection regulations.The subject of research. A change in the fire resistance limit of steel i-girders, caused by the PS heating, depends on the area of the PS cross section and the location of the point of its attachment.The goal. The goal of the research is to analyze the effect, produced by the area of the cross section and the point of attachment, on the fire resistance limit of fireproof steel i-girders in the course of heating.Materials and methods. ANSYS Workbench 2020 R2 (student version) was applied to perform the numerical simulation.Results. The simulation has shown that the PS, having no fireproofing, influences the fire resistance limit of fireproof structures.Conclusions. Currently available methods of analysis of the fire resistance of steel structures take no account of the fire resistance limit reduction, caused by the heating of the PS that has no fireproofing. The numerical simulation has shown that the fire proofing design must take account of the potential reduction in the fire resistance limit of fireproof structures, exposed to the heated PS that has no fire proofing. The further verification of the effect, produced by the PS, that has no fireproofing, on the time to the limit state of a fireproof steel i-girder requires fire tests and supplementary investigations to evaluate the influence of the PS on the heating of vertical fireproof constructions, including the case of the hydrocarbon fire mode.

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Fire Resistance of Building Materials as a Basic Characteristic of Fire Resistance Kinetic Theory

Cited by 2 publications

References 0 publications

Basic principles in the theory of force and thermal force resistance of concrete

Basic principles in the theory of force and thermal force resistance of concrete

The research into the heating effect of secondary steel structures, having no fire proofing, on the fire resistance of fireproof steel beams

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