SUSCOS - Politehnica University of Timișoara
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FIRE Concrete structures SUSCOS 1 22/10/2012 Jean-Marc Franssen
Transcript of 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
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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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