Heat transfer principles in thermal calculation of structures in fire

When exposed to high temperatures, such as in a fire situation, the physical and resistance characteristics of the materials employed in the structure deteriorate as the temperature increases. This fact promotes a considerable loss in the bearing capacity and stiffness of the structural system. The verification of a structure exposed to fire depends primarily and principally on the thermal analysis of the cross section of the structural element. This analysis permits determination of the temperature variation or temperature range in the element from the boundary conditions provided by the fire model adopted. As such, this study had the objective of performing a thermal analysis in a transient regime by means of a finite element method on steel-concrete composite cross sections that are employed in civil construction through use of the Computational System for Advanced Structural Analysis/Fire Analysis (CS-ASA/FA). Two cross sections are analyzed and the results obtained were satisfactory. In addition, different iterative solution processes were adopted in the analysis. Parametric studies were also performed related to the mesh variation of the finite elements and time increase. From the results, it was possible to conclude that CS-ASA/FA can supply the necessary information when a thermo-structural analysis is performed for the evaluation of strength and stiffness losses of the structural material when exposed to fire.

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“…In the international context, works by Othuman andWang (2011), Zandi et al (2012), Zang and Usmani (2015), and Wong (2017) can be highlighted.…”

Section: Figurementioning

confidence: 98%

Thermal analysis of steel-concrete composite cross sections via CS-ASA/FA

et al. 2018

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“…There have been a number of approaches to PFP modelling [7,8,[21][22][23][24][25][26][27][28]. The key difficulty is the number of thermal quantities and rate parameters that need to be measured, which effectively limits modelling to a few formulations where the necessary parameters are known.…”

Section: T1mentioning

confidence: 99%

A propane burner test for passive fire protection (PFP) formulations containing added halloysite, carbon nanotubes and graphene

Gibson

Wan-Jusoh

Kotsikos

2018

Polymer Degradation and Stability

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Passive fire protection materials (PFP) have been characterised quantitatively using a constant heat flux propane burner test, with the PFP attached to a steel substrate. The burner test was able to produce a large, constant heat flux, to simulate a severe fire condition. The heat transferred through the PFP was calculated from the temperature rise of the steel. A simplified model is discussed, to account for different combinations of substrate thickness, PFP thickness, heat flux and exposure time. It was found that, despite the complex processes of resin decomposition and intumescence, heat transmission could be modelled, to a reasonable approximation, by treating the PFP as a material with single point values of apparent thermal diffusivity and conductivity. This leads to an equation that can be used to characterise PFPs and indeed to specify their required thickness. The burner test was employed to interpret the effects of adding small quantities of three nano-materials: halloysite nanotubes (HNT), multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GNP), to a standard PFP formulation. It was found that HNT Q (J.m-2) cumulative heat flow into metal substrate.

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“…In practice, the adiabatic surface temperatures of interest can be approximately measured by a plate thermometer [27]. Consider the case at high temperature (above about 400 o C), where convection is not the dominant mode of heat transfer in fire [28]; from Eq. 3 or 4 the adiabatic surface temperature measured by a plate thermometer can be used to predict the net heat flux to a surface with a different emissivity.…”

Section: The Fire Structure Interfacementioning

confidence: 99%

Integrated Fire-Structure Simulation of a Localzied Fire Test on a Ceiling Steel Beam

Zhang¹,

Li²

2017

Volume 13 Number 2

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Performance based method is increasingly used for structural fire safety design of modern buildings with large enclosure. The design fire scenarios in large enclosure are localized fires. Integrated fire-structure simulation method is required to accurately predict the response of structures in realistic fires (e.g. localized fires). In recent years, there is an increase in use of FDS (Fire Dynamics Simulator) -FEM (finite element method) approach for performance-based structural fire design. This paper discusses the FDS-FEM approach for predicting the thermal response of structures subjected to localized fires. A fire-structure interface, named adiabatic surface temperature (AST), was applied to transfer data from FDS to ANSYS. By comparing the predicted and measured heat fluxes and steel temperatures of a steel ceiling beam exposed to a localized fire condition, the FDS-FEM method was tested. The FDS predicted heat fluxes matched well with the test data. The difference between the predicted and measured maximum heat fluxes was within 6% for the investigated two cases. The FDS-FEM method gave good prediction of the steel temperatures. The over-prediction of maximum steel temperature was within 11% for the investigated case. The methods described in this study provide a feasible way to study the complex behavior of structures in realistic fires.

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Heat transfer principles in thermal calculation of structures in fire

Cited by 32 publications

References 17 publications

Thermal analysis of steel-concrete composite cross sections via CS-ASA/FA

Thermal analysis of steel-concrete composite cross sections via CS-ASA/FA

A propane burner test for passive fire protection (PFP) formulations containing added halloysite, carbon nanotubes and graphene

Integrated Fire-Structure Simulation of a Localzied Fire Test on a Ceiling Steel Beam

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