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# EN 1992-1-2:2004. Structural fire design

QuickField simulation example

A concrete slab is exposed to a standard fire (ISO 834).

Problem Type
Plane-parallel problem of transient heat transfer.

Geometry

Given
Fire temperature varies in time and convection coefficient is 25 W/K-m², emissivity coefficient of concrete is 0.7. The standard fire temperature-time curve is defined by the ISO 834*:
T(t) = T0 + 345*log10(8*t + 1), where t is time in minutes and T0=20°C is an initial temperature.

Concrete thermal conductivity λ(T) = 1.36 - 0.136*(T/100) + 0.0057*(T/100)² W/m-K

Concrete specific heat capacity C depends on temperature

Concrete density ρ variation with temperature is influenced by water loss.

Calculate the temperature field.

Solution
In EN 1992-1-2:2004** only a quarter of the slab is simulated. So we also utilize symmetry of the model and simulate only a quarter.
In QuickField the density ρ must be a constant. We specify density to be ρ(20°C) and attenuated specific heat dependency to take into account ρ(T):
C'(T) = C(T) * ρ(T)/ρ(20°C);

Results
Temperature profiles 30 minutes and 60 minutes after the fire is started. Reference:
*ISO 834-1:1999. Fire-resistance tests — Elements of building construction — Part 1: General requirements
**EN 1992-1-2:2004 Design of concrete structures - Part 1-2: General rules - Structural fire design. 