Hazards 29-069 Comparison of Building Design€¦ · Rafael Callejas-Tovar, PhD, P.E. and Joshua...
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Hazards 29 – Design Engineering Rafael Callejas-Tovar, PhD, P.E. and Joshua Bruce-Black Thursday 23 May 2019 | 10:55AM–11:20AM Comparison of Building Design: Design Accidental Loads vs. Risk-Based ©2019 Baker Engineering and Risk Consultants, Inc.
Transcript of Hazards 29-069 Comparison of Building Design€¦ · Rafael Callejas-Tovar, PhD, P.E. and Joshua...
Hazards 29 – Design Engineering
Rafael Callejas-Tovar, PhD, P.E. and Joshua Bruce-BlackThursday 23 May 2019 | 10:55AM–11:20AM
Comparison of Building Design: Design Accidental Loads vs. Risk-Based
©2019 Baker Engineering and Risk Consultants, Inc.
Building Damage due to Explosion Event
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 2
• Explosions, fires, and/or toxic
releases are potential hazards
inherent to the operations of many
facilities.
• Designing buildings for the worst-
case consequences without
considering their likelihood is the
conservative approach.
o This can often be infeasible or cost-
prohibitive due to the predicted
severity of the worst-case events.
Introduction
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• An alternative building design approach that considers not only the
consequence of the events but also their likelihood is becoming more
prevalent throughout industry.
• In this presentation we will use examples to discuss the benefits and
shortcomings of two building design approaches:
Design Accidental Loads (DAL)
Consequence Load at a Frequency
Quantitative Risk Analysis (QRA)
Comprehensive Risk Calculations
Building Design Approaches that consider Likelihood of Events
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• The frequency-consequence (DAL) approach and the QRA approach have
similar calculation stages, but the depth of the analysis and their design
thresholds are different.
Stage 1: Consequence
Analysis
Stage 2: Frequency Analysis
Building Design Approaches that consider Likelihood of Events (cont.)
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 5
Schematic of Frequency-Consequence (or DAL) Approach
DAL = Design
Accidental Load
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Major Steps of a Consequence and Risk Assessment
•Identify & Document:
•Hazard Sources
•Congestion / Confinement
•Buildings
•Mitigation Barriers
•Weather / Wind data
Definition of Scenarios and
Relevant Parameters
•Discharge and Dispersion
•Flammable / Toxic Concentration and Vulnerability
•Fire: Thermal Radiation and Vulnerability
•Blast Overpressure and Impulse
•Building Damage
Evaluate Potential Impacts: Occupant
Vulnerability •Define:
•Frequency of Events
•Occupancy
•Reliability of Mitigation Barriers
•Weather / Wind Condition Probabilities
QRA Model Set Up –Import Consequence
Modeling Results
•Individual Risk
•Societal Risk
•FN Curves, etc.
Calculate Risk and Compare Results vs.
Tolerance Criteria
Consequence Analysis Risk Analysis
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• Key Concepts:
o Building Damage Level (BDL)
o Pressure-Impulse Curves (P-i Curves)
o Occupant Vulnerability (OV)
Explosion Risk Design – Example Pressure-Impulse Diagram
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Schematic of Quantitative Risk Analysis (QRA) Approach
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Schematic of Quantitative Risk Analysis (QRA) Approach (cont.) – Explosion Risk Example
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Building Design Discussion
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There are three main differences in
employing a frequency-consequence
approach vs. using a risk-based
approach in building design:
Event Duration
Occupant Vulnerability
Occupancy
Frequency-Consequence (DAL) Approach vs. Risk-Based Approach
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Building Design Discussion:Importance of Event Duration
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Frequency-Consequence Approach vs. Risk-Based Approach: Event Duration
Occupant vulnerability depends not only on the magnitude of the impact (pressure, thermal radiation flux, toxic concentration) at a building, but also on the duration of the event.
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• Consider a new building that has to
be designed for these blast loads
using the frequency-consequence
approach.
Example 1 – Design of New Building against Explosion
Blast
Load
ID#
Overpressure
(barg)
Impulse
(Pa-s)
Frequency
(/year)
1 0.295 1255 5.8E-8
2 0.289 896 4.8E-7
3 0.289 708 6.1E-7
4 0.279 1257 6.8E-7
5 0.266 1336 3.9E-7
6 0.264 1166 9.0E-7
7 0.247 965 8.4E-7
8 0.245 935 8.8E-7
9 0.239 1233 1.1E-6
10 0.233 1106 1.8E-6
11 0.213 1383 7.5E-6
12 0.209 1201 8.4E-6
13 0.179 1548 5.7E-6
14 0.169 932 5.5E-6
15 0.167 1072 9.8E-7
16 0.165 1259 1.6E-6
17 0.165 998 6.6E-6
18 0.164 1315 2.5E-6
19 0.163 738 4.9E-6
20 0.152 1108 7.9E-6
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 15
Example 1 – Frequency-Consequence Exceedance Curve
Blast
Load
ID#
Overpressure
(barg)
Impulse
(Pa-s)
Frequency
(/year)
1 0.295 1255 5.8E-8
2 0.289 896 4.8E-7
3 0.289 708 6.1E-7
4 0.279 1257 6.8E-7
5 0.266 1336 3.9E-7
6 0.264 1166 9.0E-7
7 0.247 965 8.4E-7
8 0.245 935 8.8E-7
9 0.239 1233 1.1E-6
10 0.233 1106 1.8E-6
11 0.213 1383 7.5E-6
12 0.209 1201 8.4E-6
13 0.179 1548 5.7E-6
14 0.169 932 5.5E-6
15 0.167 1072 9.8E-7
16 0.165 1259 1.6E-6
17 0.165 998 6.6E-6
18 0.164 1315 2.5E-6
19 0.163 738 4.9E-6
20 0.152 1108 7.9E-6
0.23 barg
Impulse ?
• Importance of event duration -- Different building designs can meet the design
overpressure at different impulse values (durations).
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 16
Example 1 – Proposed Building Designs
Building Design 1
DAL = 0.23 barg
Short Impulse = 700 Pa*s
Building Design 2
DAL = 0.23 barg
Medium Impulse = 1100 Pa*s
Building Design 3
DAL = 0.23 barg
Long Impulse = 1500 Pa*s
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 17
• Importance of event duration --
Different building designs can meet
the design overpressure at different
impulse values (durations).
• Risk is expected to be different for
each design.
Example 1 – P-i Blast Scatter Plot for Three Building Designs of the Same Construction Type
Building Design 1DAL = 0.23 barg
Short Impulse
Building Design 2DAL = 0.23 bargMedium Impulse
Building Design 3DAL = 0.23 barg
Long Impulse
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Example 1 – Blast Loads and Associated Damage Level and Risk for Different Building Designs
Blast
Load
ID#
Overpressure
(barg)
Impulse
(Pa-s)
Frequency
(/year)
Steel-
Frame
Design 1
Steel-
Frame
Design 2
Steel-
Frame
Design 3
Steel-
Frame
Design 1
Steel-
Frame
Design 2
Steel-
Frame
Design 3
Steel-
Frame
Design 1
Steel-
Frame
Design 2
Steel-
Frame
Design 3
1 0.295 1255 5.8E-8 4 3 2.5 1 0.39 0.025 5.8E-8 2.3E-8 1.4E-9
2 0.289 896 4.8E-7 4 3 2 1 0.39 0 4.8E-7 1.9E-7 0.0E+0
3 0.289 708 6.1E-7 4 2 1 1 0 0 6.1E-7 0.0E+0 0.0E+0
4 0.279 1257 6.8E-7 4 3 2.5 1 0.39 0.025 6.8E-7 2.7E-7 1.7E-8
5 0.266 1336 3.9E-7 4 3 2.5 1 0.39 0.025 3.9E-7 1.5E-7 9.8E-9
6 0.264 1166 9.0E-7 4 3 2.5 1 0.39 0.025 9.0E-7 3.5E-7 2.3E-8
7 0.247 965 8.4E-7 4 2 2 1 0 0 8.4E-7 0.0E+0 0.0E+0
8 0.245 935 8.8E-7 4 2 2 1 0 0 8.8E-7 0.0E+0 0.0E+0
9 0.239 1233 1.1E-6 4 3 2 1 0.39 0 1.1E-6 4.4E-7 0.0E+0
10 0.233 1106 1.8E-6 4 2 2 1 0 0 1.8E-6 0.0E+0 0.0E+0
11 0.213 1383 7.5E-6 4 2 2 1 0 0 7.5E-6 0.0E+0 0.0E+0
12 0.209 1201 8.4E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
13 0.179 1548 5.7E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
14 0.169 932 5.5E-6 2 2 1 0 0 0 0.0E+0 0.0E+0 0.0E+0
15 0.167 1072 9.8E-7 2 2 1 0 0 0 0.0E+0 0.0E+0 0.0E+0
16 0.165 1259 1.6E-6 2 2 1 0 0 0 0.0E+0 0.0E+0 0.0E+0
17 0.165 998 6.6E-6 2 2 1 0 0 0 0.0E+0 0.0E+0 0.0E+0
18 0.164 1315 2.5E-6 2 2 1 0 0 0 0.0E+0 0.0E+0 0.0E+0
19 0.163 738 4.9E-6 2 2 1 0 0 0 0.0E+0 0.0E+0 0.0E+0
20 0.152 1108 7.9E-6 2 2 1 0 0 0 0.0E+0 0.0E+0 0.0E+0
Total = 1.5E-5 1.4E-6 5.1E-8
Building Damage Level
Explosion Occupant
Vulnerability Explosion LSIR (APoD)
Explosion
Individual Risk
All designs satisfy the DAL but their risk is quite different.
Design Design
Overpressure
(barg)
Design Impulse
(Pa*s)
Meets Frequency-
Consequence
Threshold?
Explosion Location
Specific Individual
Risk (APoD)
Steel Frame #1 0.23 700 YES 1.5E-5
Steel Frame #2 0.23 1100 YES 1.4E-6
Steel Frame #3 0.23 1500 YES 5.1E-8
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 19
Example 1 – Summary
- All designs satisfy the DAL but their risk is
quite different.
- If a risk-based approach is used and risk
threshold is not met, modifications to the
designs are required (iterative approach).
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 20
Example 1 – Importance of Event Duration for Toxic and Fire Events
1024 ppm 205 kW/m2
Duration? Duration?
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Building Design Discussion:Occupant Vulnerability
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• Consider the same blast loads
shown in Example 1.
• Three potential identical building
designs constructed with different
materials are proposed:
o Pre-engineered metal building
o Steel-frame building
o Reinforced CMU (concrete masonry unit)
building
Example 2 – Occupant Vulnerability (OV)
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 23
Example 2 – Risk for Three Identical Building Designs Constructed with Different Materials
,Blast
Load
ID#
Overpressure
(barg)
Impulse
(Pa-s)
Frequency
(/year)
Pre-Eng.
Metal
Steel-
Frame
Reinforced
CMU
Pre-Eng.
Metal
Steel-
Frame
Reinforced
CMU
Pre-Eng.
Metal
Steel-
Frame
Reinforced
CMU
1 0.295 1255 5.8E-8 3 3 3 0.18 0.2 0.28 1.0E-8 1.2E-8 1.6E-8
2 0.289 896 4.8E-7 3 3 3 0.18 0.2 0.28 8.7E-8 9.7E-8 1.4E-7
3 0.289 708 6.1E-7 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
4 0.279 1257 6.8E-7 3 3 3 0.18 0.2 0.28 1.2E-7 1.4E-7 1.9E-7
5 0.266 1336 3.9E-7 3 3 3 0.18 0.2 0.28 7.1E-8 7.9E-8 1.1E-7
6 0.264 1166 9.0E-7 3 3 3 0.18 0.2 0.28 1.6E-7 1.8E-7 2.5E-7
7 0.247 965 8.4E-7 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
8 0.245 935 8.8E-7 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
9 0.239 1233 1.1E-6 3 3 3 0.18 0.2 0.28 2.0E-7 2.3E-7 3.2E-7
10 0.233 1106 1.8E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
11 0.213 1383 7.5E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
12 0.209 1201 8.4E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
13 0.179 1548 5.7E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
14 0.169 932 5.5E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
15 0.167 1072 9.8E-7 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
16 0.165 1259 1.6E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
17 0.165 998 6.6E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
18 0.164 1315 2.5E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
19 0.163 738 4.9E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
20 0.152 1108 7.9E-6 2 2 2 0 0 0 0.0E+0 0.0E+0 0.0E+0
Total = 6.6E-7 7.3E-7 1.0E-6
Building Damage Level
Explosion Occupant
Vulnerability Explosion LSIR (APoD)
OV and resulting explosion individual
risk are different for each building
Frequency-Consequence Approach: Design Overpressure is the same for all Buildings (same blast loads)
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 24
• Building of concern is susceptible to
toxic impacts from multiple H2S
sources.
Example 3 – Occupant Vulnerability (OV) on Shelter-In-Place (SIP) Building Designs
1024 ppm
Duration?Internal Concentration?Occupant Vulnerability?
Scenario: Weather
Scenario
Frequency
(/year)
External
Concentration
(ppm)
HVAC
Isolation
Success &
0.1 ACHs
HVAC
Isolation
Success &
0.3 ACHs
HVAC
Isolation
Success &
3 ACHs
No
Isolation
HVAC
Isolation
Success &
0.1 ACHs
HVAC
Isolation
Success &
0.3 ACHs
HVAC
Isolation
Success &
3 ACHs
Source-X-150: D3.7/Wind Direction: 0 2.9E-6 581 55 150 552 579 0.01 0.09 0.58 0.63
Source-X-150: D3.7/Wind Direction: 22.5 3.3E-6 676 64 175 642 674 0.01 0.15 0.69 0.73
Source-X-150: D3.7/Wind Direction: 45 4.3E-7 551 52 143 523 549 0.00 0.08 0.54 0.59
Source-X-150: F1.8/Wind Direction: 0 4.7E-6 1023 97 265 972 1021 0.02 0.11 0.83 0.92
Source-X-150: F1.8/Wind Direction: 22.5 2.1E-6 1460 139 378 1387 1457 0.08 0.29 0.95 0.98
Source-X-150: F1.8/Wind Direction: 45 4.2E-6 943 90 244 896 941 0.01 0.08 0.79 0.90
Internal Concentration (ppm) Toxic OV
Toxic OV
Isolation
Failure
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 25
Example 3 – External / Internal Concentration, Toxic OV, and Risk Results
0.1 ACHs 0.3 ACHs 3 ACHs
No
Isolation
Source-X-150: D3.7/Wind Direction: 0 1.9E-7 4.1E-7 1.7E-6 1.8E-6
Source-X-150: D3.7/Wind Direction: 22.5 2.7E-7 6.8E-7 2.3E-6 2.4E-6
Source-X-150: D3.7/Wind Direction: 45 2.5E-8 5.3E-8 2.3E-7 2.5E-7
Source-X-150: F1.8/Wind Direction: 0 5.0E-7 8.9E-7 3.9E-6 4.3E-6
Source-X-150: F1.8/Wind Direction: 22.5 3.6E-7 7.7E-7 2.0E-6 2.1E-6
Source-X-150: F1.8/Wind Direction: 45 4.2E-7 6.9E-7 3.4E-6 3.8E-6
Total = 1.8E-6 3.5E-6 1.4E-5 1.5E-5
Toxic LSIR (APoD)
Scenario: Weather
Risk results depend not only on the external concentration at the building, but also depend on internal concentration, which is affected by the toxic design of the building.
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Building Design Discussion:Occupancy Considerations
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Difference in Using a Frequency (DAL) Criterion and Societal Risk-Based Criterion in Building Design on the Overall Risk of a Facility
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It is important to understand the benefits and drawbacks of the design basis used for building design.
Design Basis Used
Frequency based can be more straightforward to implement but has inherent limitations.
Frequency-Based (DAL) vs. Risk-Based Design (QRA)
Comprehensive: Considers scenario duration, occupant vulnerability per scenario, and building
occupancy.
Strengths of Risk-Based Design
May require complex modelling, additional effort, and additional time than frequency-based.
Limitations of Risk Based Design
1
2
3
4
Conclusions
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM
www.BakerRisk.com
29Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM
Thank you!I will be happy to answer any questions.
Rafael Callejas-Tovar, PhD, P.E.
Understanding Hazards and Risks
Hazards 29 | Comparison of Building Design: Design Accidental Loads vs. Risk-Based | 23 May 2019 | 10:55AM–11:20AM 30
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