With this module you can conduct a structural analysis for fire scenarios based on the advanced calculation method for 2D and 3D beam structures. Steel, reinforced concrete, timber and composite sections are used in this analysis based on the following standards:

• EN 1992-1-2: 2004
• DIN EN 1992-1-2
• EN 1993-1-2: 2005
• ENV 1994-1-2: 1997
• EN 1995-1-2: 2010

The analysis consists of a thermal calculation and a mechanical calculation.
The calculation steps are outlined below. For more detailed information, refer to this excerpt from the user manual.

Thermal Calculation

The temperature distributions in the sections are determined as part of a nonlinear time-step integration.

Various materials such as reinforced concrete, steel or insulation can be used within a section. If necessary, user-defined curves can be specified for the thermal properties of these materials.

The time increment and duration can be specified by the user and then incorporated into the thermal analysis and the subsequent mechanical analysis. The result is a temperature profile for all specified times.

Time-temperature curve at a selected section point

Mechanical Analysis

As part of the mechanical analysis, a nonlinear time-step calculation is performed based on the 'Advanced Calculation Method' of the EN 1992-1-2, EN 1993-1-2, EN 1995-1-2 standards.

The thermal strains and stress-strain curves in the section are determined using the temperature profiles from the thermal analysis.

Related stress-strain curves for concrete with quartz additives

Temperature and stress distribution in a reinforced concrete section

The example below was taken from Upmeyer, Dissertation Universität Hannover 2001 and is based on a fire test conducted in Brauschweig in 1995.

   Composite frame with dimensions, load and sections

The fire stress occurs according to the unit temperature-time curve. Flame is applied to the frame member from the bottom and to the frame strut from all sides.

Temperature profile of the used sections at time t=90 min

Geometric and physical nonlinearities are included in the time-step calculation process. At the end of the calculation, the time-dependent deformations, internal forces and support reactions are available.

The time displacement curve depicted below matches the test results very well. Even the calculated failure time of 149 min differs only slight from the test result (150 min).

Superelevated deformation figure of the frame shortly before failure (t=148 min)

Time-displacement curve uz in the horizontal frame member (1)

Time-displacement curve ux in the frame strut (2)

Thermal Analysis

• Thermal actions as per EN 1991-1-2
• User-defined fire curves
• Optional consideration of moisture content in concrete
• Optional consideration of reinforcement layers
• Non-uniform temperature load
• Heat transfer to connected components
• Radiation and convection on internal boundaries
• User-defined calculation increments

Mechanical analysis

• Temperature-dependent material properties
• Consideration of different fire scenarios
• Nonlinear time-step calculation of the structure

References:

DIN EN 1991-1-2/NA:2010-12
Nationaler Anhang – National festgelegte Parameter –
(National Annex – Nationally Determined Parameters –)
Eurocode 1: Einwirkungen auf Tragwerke –
Teil 1-2: Allgemeine Einwirkungen - Brandeinwirkungen auf Tragwerke.
(Eurocode 1: Actions on Structures – Part 1-2: General Actions – Actions on Structures exposed to Fire)
Publisher: DIN Deutsches Institut für Normung e.V., Berlin.
Beuth Verlag, Berlin 2010.

DIN EN 1992-1-2/NA:2010-12
Nationaler Anhang – National festgelegte Parameter –
(National Annex – Nationally Determined Parameters –)
Eurocode 2: Bemessung und Konstruktion von Stahlbeton- und Spannbetontragwerken –
Teil 1-2: Allgemeine Regeln - Tragwerksbemessung für den Brandfall.
(Eurocode 2: Design of Concrete Structures – Part 1-2: General Rules – Structural Fire Design)
Publisher: DIN Deutsches Institut für Normung e.V., Berlin.
Beuth Verlag, Berlin 2010.

DIN EN 1993-1-2/NA:2010-12
Nationaler Anhang – National festgelegte Parameter –
(National Annex – Nationally Determined Parameters –)
Eurocode 3: Bemessung und Konstruktion von Stahlbauten –
Teil 1-2: Allgemeine Regeln - Tragwerksbemessung für den Brandfall.
(Eurocode 3: Design of Steel Structures – Part 1-2: General Rules – Structural Fire Design)
Publisher: DIN Deutsches Institut für Normung e.V., Berlin.
Beuth Verlag, Berlin 2010.

DIN EN 1995-1-2/NA:2010-12
Nationaler Anhang – National festgelegte Parameter –
(National Annex – Nationally Determined Parameters –)
Eurocode 5: Bemessung und Konstruktion von Holzbauten –
Teil 1-2: Allgemeine Regeln - Tragwerksbemessung für den Brandfall.
(Eurocode 5: Design of Timber Structures – Part 1-2: General Rules– Structural Fire Design)
Publisher: DIN Deutsches Institut für Normung e.V., Berlin.
Beuth Verlag, Berlin 2010.

EN 1991-1-2:2010
Eurocode 1: Actions on Structures –
Part 1-1: General Actions – Actions on Structures exposed to Fire
Publisher: CEN European Committee for Standardization, Brussels.
Beuth Verlag, Berlin 2010.

EN 1992-1-2:2004/AC:2008
Eurocode 2: Design of Concrete Structures – Part 1-2: General Rules – Structural Fire Design
Publisher: CEN European Committee for Standardization, Brussels.
Beuth Verlag, Berlin 2008.

EN 1993-1-2:2005/AC:2009
Eurocode 3: Design of Steel Structures – Part 1-2: General Rules – Structural Fire Design
Publisher: CEN European Committee for Standardization, Brussels.
Beuth Verlag, Berlin 2009.

ENV 1994-1-2:1997
Eurocode 4: Design of composite Steel and Concrete Structures – Part 1-2: General Rules – Structural Fire Design
Publisher: CEN European Committee for Standardization, Brussels.
Beuth Verlag, Berlin 1997.

EN 1995-1-2:2010
Eurocode 5: Design of Timber Structures – Part 1-2: General Rules – Structural Fire Design
Publisher: CEN European Committee for Standardization, Brussels.
Beuth Verlag, Berlin 2010.

A Heat Transfer Textbook,
J.H.Lienhard IV and J.H.Lienhard V, Phlogiston Press Cambridge, Massachusetts, U.S.A., 2008.

Engineering Guide for Fire Protection (Leitfaden Ingenieurmethoden des Brandschutzes),
Technical Report vfdb TB 04/01, Eds. Dietmar Hosser, Altenberge, Braunschweig, Germany, 2006.

Design of Load-Bearing Systems for Multi-Floor Buildings with Steel Construction for Realistic Fire Stress
(Bemessung von Tragsystemen mehrgeschossiger Gebäude in Stahlbauweise für realistische Brandbeanspruchung), J. Zehfuss, Dissertation, Technical University of Braunschweig, Germany, 2004.

Fire Safety Design in Solid Constructions with Emphasis on Reinforced Concrete Columns (Brandschutzbemessung im Massivbau - insbesondere Stahlbetonstützen) -
Dr.-Ing. Ekkehard Richter, Institut für Baustoffe, Massivbau und Brandschutz (iBMB)
Technische Universität Braunschweig, Germany, 2007.

Load Performance of Steel-Framed Systems Subjected to Fire
(Tragverhalten stählerner Rahmensysteme bei Brandbeanspruchung), A. Rubert and P. Schaumann, Stahlbau 9/1985, Wilhelm Ernst & Sohn, Berlin, Germany.

Fire Safety Check of Concrete-Encased Composite Components For Ultimate Fire Loads
(Nachweis der Brandsicherheit von kammerbetonierten Verbundbauteilen über Grenzbrandlasten), J. Upmeyer, Dissertation, Technical University of Hannover, Germany, 2001.

Fire Resistance of Fiber, Reinforced and Prestressed Concrete
(Brandbeständigkeit von Faser-, Stahl- und Spannbeton), Austrian Federal Ministry of Transport, Innovation and Technology (Bundesministerium für Verkehr, Innovation und Technologie), Road Research (Straßenforschung) Vol. 544, Vienna, Austria, 2004.