文档介绍：欧洲建筑防火规范
Strain (%)
Stress (N/mm2)
0
300
250
200
150
100
50
20°C
200°C
300°C
400° time-temperature curves
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Compartment
Temperature
Load-bearing resistance
Time
Time
Fire severity time equivalent
Used to rate fire severity or element performance relative to furnace test.
Matches times to given temperature in a natural fire and in Standard Fire.
Fire resistance time equivalent
Standard fire
Natural fire
Element
Time-equivalence
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Furnace tests on structural elements
Fire Testing
Load kept constant, fire temperature increased using Standard Fire curve.
Maximum deflection criterion for fire resistance of beams.
Load capacity criterion for fire resistance of columns.
Problems
Limited range of spans feasible, simply supported beams only.
Effects of continuity ignored. Beams fail by “run-away”.
Restraint to thermal expansion by surrounding structure ignored.
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Structural fire protection Composite sections
Passive Protection – Composite sections
Encased
Beam
Beams with concrete encasement
Have high fire resistance (up to 180 minutes).
Involve complicated construction of joints.
Require formwork.
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Structural fire protection Composite sections
Passive Protection – Composite sections
Partially Encased Beam
Steel beams with partial concrete encasement
Concrete between flanges reduces the rate of heating of the profile's web and upper flange.
Concrete between flanges contributes to the load-bearing resistance.
The beam can be fabricated in the workshop without the use of formwork.
Simple construction of joints.
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Load reduction factor in fire
Relative to ambient-temperature design resistance
Either …..
Relative to ambient-temperature design load (more conservative)
Or more usefully…..
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Establishing Fire Resistance: Strategies
Eurocodes allow fire resistance to be established in any of 3 “domains”:
Time: >
Load resistance: >
Temperature: > d
U