Analytical Equations Applied to the Study of Steel Profiles under Fire According to Different Nominal Temperature-Time Curves

Pedro N Oliveira,Raul D S G Campilho,Elza M M Fonseca,Paulo A G Piloto

doi:10.3390/mca26020048

Pedro N Oliveira, Raul D S G Campilho + Show 2 more

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https://doi.org/10.3390/mca26020048

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Abstract

Some analytical methods are available for temperature evaluation in solid bodies. These methods can be used due to their simplicity and good results. The main goal of this work is to present the temperature calculation in different cross-sections of structural hot-rolled steel profiles (IPE, HEM, L, and UAP) using the lumped capacitance method and the simplified equation from Eurocode 3. The basis of the lumped capacitance method is that the temperature of the solid body is uniform at any given time instant during a heat transient process. The profiles were studied, subjected to the fire action according to the nominal temperature–time curves (standard temperature-time curve ISO 834, external fire curve, and hydrocarbon fire curve). The obtained results allow verifying the agreement between the two methodologies and the influence in the temperature field due to the use of different nominal fire curves. This finding enables us to conclude that the lumped capacitance method is accurate and could be easily applied.

Highlights

The European standards represent simplified equations for the temperature calculation of steel structures exposed to fire. This present paper examines the temperature distribution in different ranges of hotrolled steel profiles when submitted to fire at all four sides
One method consisting of the simplified equation from Eurocode 3 [24], which is based on the principle that the heat entering the steel over the exposed surface area in a small-time-step is equal to the heat required to raise the temperature of the steel, assuming that the steel temperature is uniform over the cross-section [27]
Regarding the use of analytical methods, it was possible to verify that the lumped capacitance method (LC) method can be used in design to determine the temperature evolution for profiles submitted to different fire scenarios since the results obtained agree with those of the simplified equation recommended by the Eurocode 3 for the studied profiles

Summary

Introduction

Temperaturetime curves are analytical functions of time that give a temperature, and they are termed nominal because they do not represent a real fire but instead measure temperatures of previous fires and are standardized. Since they are conventional, such relationships are to be used in a prescriptive regulatory environment, and any requirement that is expressed in terms of a nominal curve is prescriptive. Eurocode 1 introduces three different nominal temperature-time curves: the standard temperature-time curve, the external temperaturetime curve, and the hydrocarbon temperature-time curve Each of these curves is used for special types of fires [1,2,3]

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