Response analysis of the power plant steel structure
building under post-earthquake fire
Reporter: Zhang Zhiqian
Civil structure designer
Company： State Nuclear Electric Power Planning Design ＆ Research Institute
国家核电 www.snptc.com
Company introduction in short
Our main business is to provide planning, consultation, survey, design, technical R&D, EPC and
technical support services to domestic and overseas entities, in the domains of nuclear power, thermal
power, power grid and renewable energy sources.
Report Contents
1、Introduction and background
2、The power plant structure model---earthquake only
3、The power plant structure model--- post-earthquake fire
4、Conclusion
1、Introduction and background
Earthquake is a sudden devastating natural disaster , One strong earthquake often can cause
immeasurable loss within a few seconds or minutes. Usually the earthquake will induce a variety
of secondary disasters, the earthquake fire is most likely to happen, which is the most dangerous.
The strength of steel structure building is high, seismic performance is good, but in a
powerful earthquake, weak parts of the factory building will still produce irreversible
deformation, causing the structure internal force redistribution. If earthquake cause secondary
fire, exacerbate the damage of structure itself, and even lead to structure continuous collapse.
Contents
1、Introduction and background
2、The power plant structure model---earthquake only
3、The power plant structure model--- post-earthquake fire
4、Conclusion
Power plant main building plan drawing
Auxiliary house
Turbine house
First
span
Power plant main building cross-section drawing
2、The power plant structure model---earthquake only
In order to analyze different earthquake conditions influence the structure with fire,
according to the code for seismic design of buildings, two kinds of fortification intensity
analysis of the structure response is simulated, under 7 degrees (0.15 g) and 8 degrees (0.30
g).
The seismic action as initial conditions to analyze the fire, choose one kind of wave
seismic for analysis. It is EL Centro seismic wave, the lateral load following with the GB
code.
Analyze the steel structure response under earthquake, calculate the structure response
under two different fortification intensity.
2、The power plant structure model---earthquake only
In the left picture, the maximum story drift ratio of each floor, showing that story drift ratio
of 7 degrees is much smaller than 8 degrees , The story drift ratio under two kinds of fortification
intensity does not exceed the standard regulation, in the figure the second floor story drift ratio is
more larger, the second story drift ratio is close to the limit when it is 8 degrees , The first and
second floor will be analyzed as the weak parts. In the right picture, it is comparison of the story
shear force under two different earthquake intensity, showing that the story shear force is strongly
influenced by seismic action, the more intense, the larger story shear force.
The maximum story drift ratio of each floor
Comparison of the story shear force
Contents
1、Introduction and background
2、The power plant structure model---earthquake only
3、The power plant structure model--- post-earthquake fire
4、Conclusion
3、The power plant structure model--- post-earthquake fire
The development of a compartment fire may roughly be divided into four stages :fire growth,
Flashover, steady burning, decay.
Growth Steady
burning
Temperature
Flash
over
Decay
C
B
A
Time
Development of a compartment fire
3、The power plant structure model--- post-earthquake fire
About fire analysis, as shown in the left picture, the temperature curve adopted ISO
international standard heating up curve. After the earthquake, different fire positions are
selected on the first and second floor of the structure to calculate.
The flammable explosive room is easy to produce fire, as shown in the right figure, we
choose the corner room and the middle room to analyze the fire deformation , assume that the
first floor and the second floor are on fire at the same time.
ISO International temperature curve
The position of the burning room
3、The power plant structure model--- post-earthquake fire
From the below pictures, we can see that the limit temperature of the structure, not
considering earthquake is higher than that considering the earthquake, the structure limit
temperature of 8 degrees earthquake is rarely the minimum temperature.
Displacement of steel-column joint
3、The power plant structure model--- post-earthquake fire
In addition, from the pictures, we can also see that the deformation of the structure under
the action of fire process is divided into two stages: the components fired heat expansion
stage and failure stage.
Displacement of steel-column joint
3、The power plant structure model--- post-earthquake fire
As shown in the pictures, the maximum axial force of not considering earthquake is greater
than that bearing the earthquake. The bigger the earthquake, the maximum axial force that
structure can withstand is smaller, the steel column buckling failure rate is faster.
Axial force variance with temperature
3、The power plant structure model--- post-earthquake fire
Considering the earthquake action, because of the formation of the beam end plastic
area, both ends of the beam and column are destroyed before steel beam midspan damage, it
is the overall failure pattern, structure failure. The earthquake damage will not only change
the structure internal force variation, even change the damage form of structure.
Axial force variance with temperature
Contents
1、Introduction and background
2、The power plant structure model---earthquake only
3、The power plant structure model--- post-earthquake fire
4、Conclusion
4、Conclusion
Research shows that considering earthquake damage and not considering the earthquake
damage, structure in local fire response regularity and failure mechanism are different. If not
considering the earthquake damage, the local fire caused the destruction of the structure are
usually local failure. If considering earthquake damage, fire structural damage can be caused
from local failure to the overall structure, and the structure refractory performance will also
be reduced, the earthquake more strongly, the phenomenon more obviously.
So that the steel factory structure fire resistance design in earthquake area, the influence
of the earthquake damage should be considered and calculated for better designing.
THANK YOU !
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Haidian District, Beijing,100095, P.R.China.
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