Structural Fire Safety Design

• Explain how the expression of a post-flashover fire temperature can be derived from thermal equilibrium and which parameters the fire curve depends on.
• List different design fires based on this model and explain the main differences between nominal fire curves and parametric fires.
• Calculate the fire characteristics (fuel load, thermal inertia, and opening factor) of any given compartment and derive the corresponding parametric fire curve.
• Predict how the variation of the fire characteristics affects the severity and duration of the fire and, in turn, the heating temperature and fire resistance of the structural elements.
• Calculate the reduction of the mechanical design load in fire condition and explain how the mechanical loads influence the critical temperature and the fire resistance of fire-exposed structural elements.
• Calculate the reduction of the mechanical properties of steel, concrete, and wood at high temperatures and after being cooled down to 20C.
• Perform the design or verification of uninsulated and insulated steel elements subjected to a parametric or standard fire.
• Perform the verification of timber elements exposed to parametric or standard fire
• Perform the verification of concrete elemetnts subjected to a parametric or standard fire during and after the fire.
• Identify possible weaknesses in the structural fire response of a building elements and indicate measures to improve its fire resistance.

The course content is divided in the following 4 main parts:

0. HEAT TRANSFER AND DESIGN FIRES
Radiation, convection, conduction equations. Flashover and fuel- and ventilation-controlled fires.
Characteristic fire parameters and derivation of parametric fire equation from heat equilibrium.
EN and DK parametric and standard fire. Fire rating and resistance classes. Mechanical loads in fire and design methods.

1. STEEL ELEMENT DESIGN
Thermal properties of steel. Section factor and Biot no. of steel profiles. Lumped heat capacity method of analysis for uninsulated steel and derivation of the steel heating temperature curve.
Insulating materials for fire protection of steel elements. Derivation of design temp. of protected steel.
Degradation of strength and stiffness of hot-rolled steel.
Calculation of load bearing capacity of unprotected and fire-protected steel elements (verification). Calculation of the insulation thickness of steel elements under given mechanical loads (design).
Thermal expansion of steel and reduction of the capacity of columns with hindered thermal expansion.

2. TIMBER ELEMENT DESIGN
Timber as combustible and building material. Firestorms and city fires.
Charring of wood. Degradation of timber mechanical properties. Cross-section reduction method and strength reduction method.
Calculation of the load bearing capacity of timber elements for parametric and standard fire (verification). Dimensioning of the cross-sections for given fire and mechanical loads (design) in simple cases.
Connections of timber elements and calculation methods for the capacity of wood-steel connections in fire.

3. CONCRETE ELEMENT DESIGN
Thermal properties of concrete. Type of concrete failures and examples of collapse. Hot and cold condition.
Concrete temp. for mono- and bi-directional heating. Symmetry lines and equivalent fully exposed section.
Degradation of mechanical properties of concrete and reinforcing steel. Permanent damage and residual strength. Damage factors (zone method) and use of CONFIRE.
Calculation of load bearing capacity (verification) of concrete elements. Transient strain and eccentrically loaded columns.

41203/41236/41953/41956/41957/41963/41964/41965, In order to be able to follow the course, it is important to possess ground knowledge of structural mechanics (statics, equilibrium and compatibility equations, elasticity, external and internal forces, stresses, strains, displacements).

It is also highly recommended to master the basics of design of steel and concrete elements.

Basic knowledge on building technology of timber structures and advance knowledge on steel and concrete structures is also recommendable.

Lectures and tutorials