SUSCOS - Politehnica University of Timișoara

FIRE

Concrete structures

SUSCOS

122/10/2012

Jean-Marc

Franssen

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EN 1992-1-2 : 2004

Content

1.General

2.Basis of design

3.Material properties

4.Design procedures

4.1. General

4.2. Simplified calculation methods

4.3. Advanced calculation methods

4.4. Shear, torsion, ancorage

4.5. Spalling

4.6. Joints

4.7. Protective layers

EN 1992-1-2 : 2004

Content

1.General

2.Basis of design

3.Material properties

4.Design procedures

4.1. General

4.2. Simplified calculation methods

4.3. Advanced calculation methods

4.4. Shear, torsion, ancorage

4.5. Spalling

4.6. Joints

4.7. Protective layers

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5. Tabulated data

5.1. Scope

5.2. General design rules

5.3. Columns

5.4. Walls

5.5. Tensile members

5.6. Beams

5.7. Slabs

6. High strength concrete

Annexes Informatives

A Temperature profiles

B Simplified calculation methods

C Buckling of columns under fire conditions

D Calculation methods for shear, torsion and anchorage

E Simplified calculation method for beams and slabs

5. Tabulated data

5.1. Scope

5.2. General design rules

5.3. Columns

5.4. Walls

5.5. Tensile members

5.6. Beams

5.7. Slabs

6. High strength concrete

Annexes Informatives

A Temperature profiles

B Simplified calculation methods

C Buckling of columns under fire conditions

D Calculation methods for shear, torsion and anchorage

E Simplified calculation method for beams and slabs

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1,0

0,9

0,8

0,7

0,6

0,5

0,4

0,3

0,2

0,1

01 2 3 4

1000°C

800°C

20°C

200°C

400°C

600°C

Strain (%)

Normalized strength

� Concrete looses strength and

stiffness for temperature higher

than 100°C.

� It does not recover during

cooling.

� Properties at elevated

temperature depend on the

coarse aggregate (calcareous

better than siliceous).

Mechanical properties at high temperatures

Concrete

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Stress-strain relationship in steel re-bars

Mechanical properties at high temperatures

Steel

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12Note: Tempcore steel may be considered as hot rolled

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Thermal properties at high temperatures

Concrete

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TABULATED DATA

Give recognised solutions for the fire resistance of members under ISO fire,

until 240 min.

Valid for normal weigth concrete (from 2000 to 2600 kg.m³) with siliceous

aggregates (if calcareous aggregates are used, minimum dimensions of the

section in beams and slabs can be reduced by 10%).

No check against spalling is required if the moisture content is less than 3%

by weight (N.D.P.).

No check is needed against shear and torsion capacity and anchorage

details.

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COLUMNS

Two methods are proposed: Method A and Method B

Both methods are valid only for columns in braced frames.

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Columns – Method A

Effective length = 3,0 meters

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Columns – Method A

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Columns

Method B

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Columns

Method B

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Annexe C (Informative)Columns

Method B

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NON LOAD-BEARING WALLS

Reduce by 10% if

calcareous

aggregates

L / b ≤ 40

For cantilevered walls, it is adviced to check stability (JMF)

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LOAD-BEARING WALLS

Utilisation of this table may be unsafe for cantilevered walls (JMF)

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BEAMS

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Note:

Moment redistribution at room temperature should not be greater than 15%.

If not, the beam must be treated as simply supported.

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SOLID SLABS

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FLAT SLABS

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SIMPLY SUPPORTED RIBED SLABS

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RIBED SLABS WITH AT LEAST ONE RESTRAINED EDGE

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SIMPLE CALCULATION METHOD

Two methods are proposed:

1)Method of the 500°C isotherm

2)Method by zones

More simple mechanical properties are used for the simple calculation method.

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The existence of curves 1 and 2, on one hand, and 3, on the other hand, is due to the fact

that the stress strain diagram has no defined horizontal plateau. The Yield strength

considered, and hence the factor kS (θ), depends on the strain that can be developed at the

ultimate limit state.

Utilisation of curves 1 or 2 is allowed only if it can be explicitly demonstrated that εs, fi ≥ 2 %.

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0

100

200

300

400

500

600

0 0,5 1 1,5 2 2,5

déformation (%)

Température (°C)

acier 20°C

acier 500°C

0,2

fs,y,20°C

fs,2%,500°C

fs,0,2%,500°C

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Method 1: 500°C isotherm method

This method is applicable only if the section has a minimum width.

Principle of the method:

1)Concrete inside the 500°C isotherm is not affected by fire.

2)Concrete outside the 500°C isotherm is completely neglegted.

3)Each bar is considered with the strength corresponding to its own temperature.

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Method 2: method by zones

More laborious, valid only for ISO fire, more precise especially for columns.

Divide the section in zones of equal width.

Exclude external damaged zones.

Estimate the average properties of the internal

zone.

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Annex A (Informative)

Temperature distributions

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Annexe E (Informative)

Simplified calculation method for beams and slabs

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APPLICATION EXAMPLES

1.Simply supported beam

2. Simply supported slab

3. Column

Examples by Thomas GERNAY

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