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Risk-based Blast Design for Safer Occupied
Buildings in Industrial Facilities
Ali Sari, Ph.D., P.E.
Genesis Houston, Structural and Quantitative Analysis Manager
E-mail: [email protected]
66th Canadian Chemical Engineering
Conference
QUÉBEC CITY, QC
OCTOBER 16-19, 2016
Ali Sari, Ph.D., P.E., Umid Azimov, P.E., Watsamon Sahasakkul
• Introduction - Motivation
• A Unified Risk based Approach - Theory
• Blast Design and Assessment of Structures
• Fire Response and PFP Optimization
• Dropped Objects
• Seismic Design and Assessment - ALE
Presentation Outline
2
Major Offshore Accidents in the Global Oil Industry
3
Geographical
Area
No. of Fatal
incidents
% of Total No.
of Fatal
Incidents
No. of
Fatalities
% of Total No.
of Fatalities
US GoM 344 62.2 611 28.1
Europe N.S. 88 15.9 574 26.4
Asia +
Australia
41 7.4 443 20.4
Other 80 14.5 543 25.0
Totals 553 100.0 2171 100.0
0
5
10
15
20
25
30
35
1970-1975 1976-1980 1981-1985 1986-1990 1991-1995 1996-2000 2000-2005 2006-2007
Pe
rce
nt
Year Period
Percent of Total Number of Fatal Incidents Percent of Total Number of Fatalities
Explosions in the Oil Industry
4
http://www.pophistorydig.com/topics/tag/oil-refinery-dangers/
March 2005
April 2016
Blast Design Load - Blast Scenarios and Associated Frequencies
5
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0.1 1 10 100
Eve
nt
Fre
qu
en
cy (
pe
r ye
ar)
Pressure (psig)
Many Scenarios! What is the design Load?
Blast Design Load - Overpressure Exceedance Curve
6
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0.1 1 10 100
Fre
qu
en
cy o
f P
or
mo
re (
pe
r ye
ar)
Pressure (psig)
~ 0.7 psi for
1E-04
~ 3.7 psi for
1E-05
~ 28 psi for
1E-06
What is the design Load?
Exceedence Curves
7
Blast Design Load - Animation
Red > 5%
8
Blast Design Load – Different Blast Assumption - Animation
9
Risk
• Use your Blast&Fire hazards experience
and knowledge
• Use Consequence analysis knowledge
well
• Know your Risk!
• “The safest risk is the one you didn't
take”.
10
11
Defining Risk – Generic Risk Matrix
Likelihood of Risk Event/Frequency
Severity
Level –
Financial
M=million
Severity
Level -
Human
A
An event has
not yet
occurred in the
industry,
Freq. = 10-5
B
An event has
occurred
somewhere in
the industry
Freq. = 10-4
C
An event has
occurred once
in the
organization or
more than
once in the
industry
Freq. = 10-3
D
An event has
occurred once
or twice in the
particular
facility lifetime
Freq. = 10-2
E
An event has
occurred at
least once per
year at the
particular
facility
Freq. < 10-1
< 0.5M USD loss
Minor
Health/safety
impact
1 2 3 4 5
0.5M – 1M USDMedium
Health/safety
impact
2 3 4 5 6
1M – 10M USD
Permanent
Injuries, high
health
impact
3 4 5 6 7
10M – 100M
USD1-3 fatalities 4 5 6 7 8
> 100M USD 3-10 fatalities 5 6 7 8 9
> 1000M USD > 10 fatalities 6 7 8 9 10
Not Acceptable
ALARP (Marginally Tolerable Risk) region
Tolerable Risk
Acceptable Risk
Event
Risk = Frequency x Consequences
12
Defining Risk – A Unified Approach
Identify Risk using
Risk Matrix
- Structural Response Analysis,
- Consequence Analysis,
Severity Levels
- Probability of Damage, Fragility Curves
- Damage Frequency Matrix,
- Individual Risk Matrix
Likelihood of Risk
- Hazard Curve
- Pressure Exceedance Curve
- Probability of Exceeding of Hitting vs Vessel Impact Energy
- Annual Exceedance Curve
Develop Mitigation/Repair/Strengthening Options,
if Risk is not acceptable
Risk Calculations – Likelihood of Risk Event/Frequency
13
𝑃𝐹𝑎𝑖𝑙 𝑖 =
𝑗,𝑘
𝑃 𝐹𝑎𝑖𝑙 𝐷 × 𝑃 𝐷 𝐴𝑗𝑘𝑖
× 𝑃(𝐴𝑗𝑘𝑖)
For each type of
accidental load
Probability of damaged
system failure under
relevant Accidental Load
Probability of damage, D given 𝐴𝑗𝑘𝑖
Probability of accidental action
at location (j) and intensity (k)
• 𝑃(𝐴𝑗𝑘𝑖) is determined by risk analysis while the other probabilities are
determined by structural reliability analysis.
• 𝑃 𝐹𝑎𝑖𝑙 𝐷 is determined by due consideration of relevant action and
their correlation with the hazard causing the damage
14
Risk Calculations – Likelihood of Risk Event/Frequency
• 𝑃 𝐹𝐼𝐼 = the probability of an individual experiencing an Fatality or Significant
Injury (FI) (individual risk)
• 𝑃(𝐴𝑖) = the probability that accident Ai occurs.
• 𝑃 𝐹𝐼|𝐴𝑖 = the conditional probability that an FI occurs, given that
event/accident Ai occurs.
• 𝑃 𝐼 𝑎𝑡 𝐴𝑖 = the probability that an individual is present when accident Ai
occurs, (occupant presence probability).
𝑃 𝐹𝐼𝐼 = 𝑖=1,𝑛
𝑃 𝐹𝐼 |𝐴𝑖 × 𝑃 𝐼 𝑎𝑡 𝐴𝑖 × 𝑃(𝐴𝑖)
The vulnerability number (VN) is the fraction of occupants with
serious, fatal injuries (FI) at a certain severity of structural damage.
15
𝑃 𝐼|𝐷𝐿𝑖 = conditional probability that an I occurs given that damage level DLi occurs.
𝑃(𝐷𝐿𝑖) = probability that damage level Di occurs.
𝑉𝑁|𝐷𝐿𝑖 = vulnerability number at a certain structural damage level DLi.
𝑂𝑃𝑃 = Occupant Presence Probability
𝑃 𝐼|𝐸𝑖 = conditional probability that an I occurs given that an escalation Ei occurs.
𝑃 𝐸𝑖|𝐷𝐿𝑖 = conditional probability that an escalation occurs given that damage level DLi occurs.
𝑉𝑁|𝐸𝑖 = vulnerability number at a certain escalation level Ei.
𝐼𝑅 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 = 𝑖=1,𝑛
𝑉𝑁|𝐷𝐿𝑖 × 𝑃 𝐼|𝐷𝐿𝑖 × 𝑃(𝐷𝐿𝑖)
Risk Calculations – Likelihood of Risk Event/Frequency
𝐼𝑅 𝑒𝑠𝑐𝑎𝑙𝑎𝑡𝑖𝑜𝑛 = 𝑖=1,𝑛
𝑉𝑁|𝐸𝑖 × 𝑃 𝐼|𝐸𝑖 × 𝑃 𝐸𝑖|𝐷𝐿𝑖 × 𝑃(𝐷𝐿𝑖)
Escalations:
• Non structural item failure in the building impact individuals,
• Debris due to Structural Failure impact individuals around the building
16
Unified Risk Based Approach for Blast Design and Assessment
Identify Risk using
Risk Matrix
Consequence:
- Structural response analysis using SDOF or MDOF or Hybrid Approach
- Develop Pressure-Impulse Curve for Each Damage Level
- Calculate OV for each damage level
- Calculate Expected fatalities for Each Damage Levels
Likelihood of Risk:
- Determine frequencies associated with structural damage levels
- Calculate Building Individual Risk
- Generate Pressure vs Duration and event frequencies
Develop Mitigation/Repair/Strengthening Options,
if Risk is not acceptable
Damage Levels for Blast Analysis for Satellite Lab - Blast Resistant Modular
Building (BRM) Option
17
Corresponding
Genesis Damage
Levels
Building Damage
LevelsDamage Description
Minor/Elastic 1 Onset of visible damage to reflected wall of building
Low 2.0
Reflected wall components sustain permanent damage requiring
replacement, other walls and roof have visible damage that is generally
repairable
Medium 2.5Reflected wall components are collapsed or very severely damaged.
Other walls and roof have permanent damage requiring replacement
High 3Reflected wall has collapsed. Other walls and roof have substantial
plastic deformation that may be approaching incipient collapse
Collapse 4 Complete failure of the building roof and a substantial area of walls
Overpressure Frequency of Exceedance Curves
18
~ 1 psi for
1E-04
~ 4.64 psi for
1E-05
~ 6.25 psi for
1E-06
Positive Phase Duration versus Overpressure – Satellite Lab
19
20
𝐼𝑅 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 = 𝑖=1,𝑛
𝑽𝑵|𝑫𝑳𝒊 × 𝑃 𝐼|𝐷𝐿𝑖 × 𝑃(𝐷𝐿𝑖)
𝐁𝐮𝐢𝐥𝐝𝐢𝐧𝐠 𝐈𝐧𝐝𝐢𝐯𝐢𝐝𝐮𝐚𝐥 𝐑𝐢𝐬𝐤 =OV × OPP × (𝐶𝑎𝑙𝑐. 𝐹𝑟𝑒𝑞𝑖 − 𝐶𝑎𝑙𝑐. 𝐹𝑟𝑒𝑞𝑖− 1)
Occupant Vulnerability (OV)
Corresponding
Genesis Damage
Levels
OV (%)
(non-structural
members designed for
Blast)
OV (%)
(non-structural members
NOT considered for Blast
design)
Minor/Elastic 0.00 0.1
Low 0.01 1.0
Medium 1.7 10.0
High 17.1 50.0
Collapse 48.8 90.0
Blast Testing
21
Explosion Source
High Speed Camera
High Speed Camera
Free-field Pressure Sensors
Free-field Pressure Sensors
Side-onPressure Sensors (Rear of Building)
Side-onPressure Sensors (Side of Building)
Reflected Pressure Sensors
(Front of Building)
Side-on Pressure Sensors (Roof of Building)
PFP Applied on Front Wall
Overall Test Setup and Instrumentation on Outside of Building
22
Side-onPressure Sensor
(Rear of Building)
Side-on Pressure Sensor (Side of Building)
Reflected Pressure Sensors
(Front of Building)
Free-field Pressure Sensor
Side-on Pressure Sensor
(Roof of Building)
Overall Test Setup and Instrumentation on Inside of Building
23
Crash Test Dummy
Interior Furniture and Office Equipment
Pressure Sensor
Pressure Sensor
Blast Testing (High Speed Camera, Movie 1)
24
Blast Testing (High Speed Camera, Movie 2)
25
Before the test After the test26
Blast Analysis of Buildings – Non Structural Members
27
Blast Analysis of Buildings – Non Structural Members
9.07
BRM Option – 8psi – 200ms Medium Response – 6 occupants
28
Summary Frequency OV BIR # of fatalities
Sum of All Available Frequencies 3.12E-04
Collapse 1.95E-06 0.90 1.76E-06 5.4
High 8.90E-06 0.50 4.45E-06 3
Medium 2.37E-05 0.10 2.37E-06 0.6
Low 2.77E-04 0.011 3.05E-06 0.066
Minor 0.00E+00 0.00E+00 0
SUM = 1.16E-05
0
1
2
3
4
5
6
0.00E+00
5.00E-07
1.00E-06
1.50E-06
2.00E-06
2.50E-06
3.00E-06
3.50E-06
4.00E-06
4.50E-06
5.00E-06
BDL 4 BLD 3 BDL 2.5 BDL 2 BDL 1
# o
f F
ata
liti
es
BIR
BRM – Non Structural Members NOT Considered
BIR Fatalities
29
Defining Risk – BRM Building Design
Likelihood of Risk Event/Frequency
Severity
Level -Human
A
An event has
not yet
occurred in
the industry,
Freq. = 10-5
B
An event has
occurred
somewhere in
the industry
Freq. = 10-4
C
An event has
occurred once
in the
organization
or more than
once in the
industry
Freq. = 10-3
D
An event has
occurred once
or twice in the
particular
facility
lifetime
Freq. = 10-2
E
An event has
occurred at
least once per
year at the
particular
facility
Freq. < 10-1
Minor
Health/safety
impact
1 2 3 4 5
Medium
Health/safety
impact
2 3 4 5 6
Permanent
Injuries, high
health impact
3 4 5 6 7
1-3 fatalities 4 5 6 7 8
3-10 fatalities 5 6 7 8 9
> 10 fatalities 6 7 8 9 10
3-10 people
1.164E-05
4.06
BRM Option – 8psi – 200ms Medium Response
30
Summary Frequency OV BIR # of fatalities
Sum of All Available Frequencies 3.12E-04
Collapse 1.95E-06 0.488 9.52E-07 2.928
High 8.90E-06 0.171 1.52E-06 1.026
Medium 2.37E-05 0.017 4.04E-07 0.102
Low 2.77E-04 0.0001 2.77E-08 0.0006
Minor 0.00E+00 0 0.00E+00 0
SUM = 2.91E-06
0
0.5
1
1.5
2
2.5
3
3.5
0.00E+00
2.00E-07
4.00E-07
6.00E-07
8.00E-07
1.00E-06
1.20E-06
1.40E-06
1.60E-06
BDL 4 BLD 3 BDL 2.5 BDL 2 BDL 1
# o
f F
ata
liti
es
BIR
BRM - Non Structural Members Considered
BIR Fatalities
31
Defining Risk – BRM Building Design – Non-Structural Members Considered
Likelihood of Risk Event/Frequency
Severity
Level -Human
A
An event has
not yet
occurred in
the industry,
Freq. = 10-5
B
An event has
occurred
somewhere in
the industry
Freq. = 10-4
C
An event has
occurred once
in the
organization
or more than
once in the
industry
Freq. = 10-3
D
An event has
occurred once
or twice in the
particular
facility
lifetime
Freq. = 10-2
E
An event has
occurred at
least once per
year at the
particular
facility
Freq. < 10-1
Minor
Health/safety
impact
1 2 3 4 5
Medium
Health/safety
impact
2 3 4 5 6
Permanent
Injuries, high
health impact
3 4 5 6 7
1-3 fatalities 4 5 6 7 8
3-10 fatalities 5 6 7 8 9
> 10 fatalities 6 7 8 9 10
3-10 people
2.9E-06
32
Defining Risk
Design/Retrofit Options ExplosionFlash
FireToxic
Jet/Pool
Fire
Total
Building
Individual
Risk
Severity
Level
(e.g.
Expected
Fatalities)
Option 1
Option 2
Option 3
Option 4
* From QRA results
except blast
33
Design/Retrofit Options vs. Risk Rating and Cost
Likelihood of Risk Event/Frequency
Severity
Level -Human
A
An event has
not yet
occurred in
the industry,
Freq. = 10-5
B
An event has
occurred
somewhere in
the industry
Freq. = 10-4
C
An event has
occurred once
in the
organization
or more than
once in the
industry
Freq. = 10-3
D
An event has
occurred once
or twice in the
particular
facility
lifetime
Freq. = 10-2
E
An event has
occurred at
least once per
year at the
particular
facility
Freq. < 10-1
Minor
Health/safety
impact
1 2 3 4 5
Medium
Health/safety
impact
2 3 4 5 6
Permanent
Injuries, high
health impact
3 4 5 6 7
1-3 fatalities 4 5 6 7 8
3-10 fatalities 5 6 7 8 9
> 10 fatalities 6 7 8 9 10
0
1
2
3
4
5
6
7
Option 1 Option 2 Option 3 Option 4
Ris
k R
ati
ng
Design Options
Risk Rating vs. Design Options
ALARP
Tolerable Risk
0
0.2
0.4
0.6
0.8
1
Option 1 Option 2 Option 3 Option 4
Co
st I
nd
ex
Design Options
Cost Index vs. Design Options
Budget Threshold
34
Design/Retrofit Options vs. Risk and Cost
Option 2
Option 1
Option 3
Option 4
3
4
5
6
7
0.5 0.6 0.7 0.8 0.9 1
Ris
k R
ati
ng
Cost Index
Risk Rating vs. Cost Index for Options
Tolerable Risk
ALARP
Expected/Budgeted Cost
• During modifications to building, causing damage to:
– Existing structure
– Equipment
– Systems
– Data
– Documents.
• Health and Safety issues related to personnel injuries.
• Control Rooms – result in unintended plant shut down.
• Delayed work on control room during planed shutdown
could result in delayed plant start up.
• cost in time / money to replace or repair damage
• Temporary relocation during construction can result in
same risks as new build
Construction Risk
35
Construction Risk
Rating
Low Risk
Medium Risk
High Risk
Very High Risk
• Requirement to bring the current building up to current
building code.
• HVAC systems to meet current design requirements.
• High skill level of trades required, not typical in the
construction region
• Extensive works will be required to bring in all utilities
to new locations
Constructability
36
Constructability
Rating
Low
Medium
Hard
Complex
Very Complex
• Extensive modification to existing structure will
require substantial building and production down
time
• Loss of productivity during relocation from old
location to new location.
• Commissioning new building
Simultaneous Operations (SIMOP)
37
SIMOP
Low Impact
Medium Impact
High Impact
Very High Impact
38
Design/Retrofit Decision - Example
Design/Retrofit
Options
Blast,
Toxic, Fire
Risk Rating
Cost RatingConstructability
RiskConstructability SIMOP
Option 1 5 0.80 Low HardMedium
Impact
Option 2 4 0.90 Very High Simple Low Impact
Option 3 6 0.65 Low ComplexVery High
Impact
Option 4 7 0.60 Medium Very Complex High Impact
• For designing new building or retrofitting existing Building, the
following items should be considered,
Risk From Blast, Toxic, Fire
Escalations due to the Building damage or response, debris type
injuries inside and outside of the building
Cost of the construction
Construction Risk
Constructability
Impacts on SIMOP
Conclusions
39
THANK YOU!Contact Details
Dr. Ali Sari, P.E.
Genesis Houston, Structural and
Quantitative Analysis Manager
Tel (Direct): +1 281 848 5033
Thank You! Questions?
