Transcript Poznan University of Technology ASSESSMENT OF PUBLIC SAFETY AFTER GAS EXPLOSION INSIDE A CIVIL ENGINEERING STRUCTURE Tomasz Łodygowski and Piotr W.

Poznan University of Technology
ASSESSMENT OF PUBLIC SAFETY
AFTER GAS EXPLOSION
INSIDE A CIVIL ENGINEERING STRUCTURE
Tomasz Łodygowski and Piotr W. Sielicki
Institute of Structural Engineering (ISE)
Poznań University of Technology
ul. Piotrowo 5, 60-965 Poznań, Poland
e-mail: [email protected],
[email protected]
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
PRESENTATION OUTLINE:
- MOTIVATION
- INTRODUCTORY REMARKS
- NUMERICAL MODEL AND COMPUTATIONS
- PUBLIC SAFETY
- CONCLUSIONS
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
MOTIVATION
PUBLIC SAFETY ASSESSMENT (during building employment for retrofitting)
- SAFE
- WOUNDED
- BADLY WOUNDED
FLOOR PLANNING (before built during a design process for changing floor configuration)
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
INTRODUCTORY REMARKS
- Full spatial modeling covers 30 by 60 m2 area and 3.5m high
- Underground concrete office rooms with plant room in „p1”
- There is an open space without blast doors, and door heads are not included
- Rigid walls represent the most risk scenario, where the reflection is the highest
Door heads are not included
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
NUMERICAL MODEL
- The analyzed scenario is:
Escaping of propane from a broken installation in the plant room
- Assumption: 50% propane-air concentration in the plant room before an explosion
- The important property of propane-air mixture; an Initial Specific Energy value bases on
Alternate Energy Systems, Inc. online data
- Propane behavior is simulated by JWL equation of the state
Type of Charge
Propane-Air
Mixture
Mass [kg]
330
Volume [m3]
172.8
Specific Energy [J/kg]
2.73e7
Density [kg/m3]
626 liquid
1.9 mixture
Detonation speed [m/s]
1680


  
 
  
   2
 exp  R1 0   B 1 
 exp  R2 0  
p  A 1 
Em 0



R


R







1 0 
2 0 
0


Z
- Air behavior is simulated by IDEAL GAS equation of the state p  p A   R T  T 
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
NUMERICAL MODEL
Coupled Eulerian-Lagrangian is used to simulate a pressure evolution in the air space inside
the office area
Source code:
Problem size:
Element size:
Analyzed time:
Computational time:
Boundary conditions:
Abaqus 6.9 Explicit code is used for calculation
2.5e6 Finite Elements EC3D8R
0.125 by 0.125 by 0.125 m3
0.2 sec
3600x15 seconds (average time for one analysis)
corridors & rooms (wall, floor, ceiling) are fixed with use of
zero velocity condition
FE requested results:
Over- Pressure values and velocity in time and space
function
Transferred requested results: Mean pressure-time dependency and impulse for every room
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
NUMERICAL MODEL
Pressure maps in time function allows for assessment of real hazard for every room, only if
some criterion is known.
t= 0.001 s
t= 0.005 s
t= 0.05 s
t= 0.1 s
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
PUBLIC SAFETY
Human tolerance to the blast output of an explosion is relatively high. However, the
orientation of a person (standing, sitting, etc.) is really important. The pressure tolerance for
short-duration blast loads is significantly higher than that for long-duration blast loads.
There are used two separate criteria, in agreement US standard i.e. Unified Facilities Criteria
(UFC) UFC 3-340-02, for assessment public safety.
1. LUNG DAMAGE
2. EARDRUMS RUPTURE
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
PUBLIC SAFETY
The mean properties are obtained for each office room and could be further compared with
safety criteria.
The results for one room (Plant Room) are presented below
Pressure – Time relation in the P1 room
Peak overpressure
Duration time
Specific Impulse*
0.62e9[ Pa ]
0.02 [ s ]
3.1e6[ Pa s / W* ]
Pressure contour lines 0.001s after detonation
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
Safe zone (below criteria)
Wounded zone (50%)
Badly wounded zone
PUBLIC SAFETY
The mean values are obtained for each room and compared with both criteria.
Safety zones base on EARDRUMS RUPTURE vs. LUNG DAMAGE criteria
Movie represents EARDRUMS RUPTURE vs. LUNG DAMAGE for badly wounded zone
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
PUBLIC SAFETY - RETROFITTING
The structure model is upgraded by rigid door heads to increase public safety in the rooms.
The results are presented below for two variants: 0.5 and 1m head high. The results are
presented with use EARDRUMS RUPTURE criteria.
0.5m head vs. 1m head for EARDRUMS RUPTURE criterion
Movie represents EARDRUMS RUPTURE for 0.5m vs 1m high doors head and badly wounded zone
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
PUBLIC SAFETY
Because of using the rigid door heads there is a significant improvement of safety in the building
The safety area (green)
increases 3 times after
retrofitting process
Safety zones for basis and upgraded (1m door head) schemes of the floor under EARDRUMS RUPTURE criterion
The safety area (green)
increases 5 times after
retrofitting process
Safety zones for basis and upgraded (1m door head) schemes of the floor under LUNG DAMAGE criterion
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010
Poznan University of Technology
CONCLUSIONS
Designer increases a value (square meters) of safety zone area in the structure after use of
rigid 1m height door heading
Obtained pressure values are comparable with real overpressure (in agreement with UFC)
Approach may be useful for predicting blast resistant for new-designed or existing structures
in relatively short time
Mesh size sensitivity must be checked for analyzing of considerably complex structure
including HVAC and elevator duct in the multi levels building
WORKSHOP 2010 ON CONSTITUTIVE MODELING IN APPLICATIONS FOR INDUSTRIAL PROCESSES KRAKÓW, 1-3 September, 2010