Blast and Eplosion Effects on Fixed and Portable Structures - Raymond Bennett

Blast Effects on Fixed and Portable Structures

Occupied Buildings and Facility Siting

March 1, 2011

Presented by:

Raymond Bennett, P.E., Ph.D.

©2007 Baker Engineering and Risk Consultants, Inc.©2009 Baker Engineering and Risk Consultants, Inc.

y

Content

Determining the Blast Load Determining the Blast Load Scenario Definition Blast Load Prediction

St t l A t Structural Assessment Building Response Damage Criteriag Occupant Vulnerability

Mitigation Summary Summary

SCENARIO DEFINITIONSCENARIO DEFINITION

Scenario Selection

Hazards associated with operations: Loss of containment Loss of containment Releases from flares Process vent stacks Atmospheric relief devices Atmospheric relief devices

Based primarily on process specific factors: Failure rate data Equipment design Equipment design Process stream composition Operating conditions

Also consider Also consider: Company and industry losses on similar types of

process or equipment

Identify Potential Sources

Define sources to represent all significant p ghazards within the processHighlight PFDs for the process to ensure

the main processing sections are covered.Supplement the list with scenarios

identified b the site (PHA LOPA etc )identified by the site (PHA, LOPA, etc.)Review the site for additional hazards

Example of Highlighted PFD

Consequence vs. Risk Approach

early north wind, early ignition (fire)N late north wind, delayed ignition (explosion)

outside of lethal concentration no impact

Initiator Wind Direction Ignition ScenarioSize Weather Toxic

ConcentrationToxic

Mitigation

outside of lethal concentration no impact10% OV Evac Successful escape from toxic plume

none PPE failure 10% perish due to toxic impact

90% OV Evac Successful escape from toxic plumePPE failure 90% perish due to toxic impact

NNE

NE

MCE

ENE

E

F1.5 ESE

SE

SSESSE

6" S

SSW

SW

WSW

Each release direction is assessed the same. Early (fire), delayed (explosion), and nonignition (toxic plume) are considered.

Release W

WNW

NW

NNW

D3

D5

B5

2"

0.5"

Each size / weather condition is assessed the same. Multiple wind directions and ignition probabilities are considered.

Each size is assessed the same. Multiple weather conditions, wind directions, and ignition probabilities are considered.

Sequence of Events (Explosion, Fire, and Toxic)(Explosion, Fire, and Toxic)

early north wind, early ignition (fire) Fsequence = Frelease x Pw x Pwind x Pign

N late north wind, delayed ignition (explosion)th i d i iti (t i l if )

Initiator Wind Direction Ignition ScenarioSize Weather Frequency

none north wind, no ignition (toxic plume if any)

NNE

NE

ENE

E

F 2 ESE

SE

SSE

6" SEach release direction is assessed the same. Early (fire), delayed (explosion),

and nonignition (toxic plume if any under 4 weather conditions) are considered.

SSW

SW

WSW

Release W

and nonignition (toxic plume if any under 4 weather conditions) are considered.

WNW

NW

NNW

B3 E h i / th diti i d th M lti l i d di ti dD 4D7

2"

0.5"

Each size / weather condition is assessed the same. Multiple wind directions and ignition probabilities are considered.

Each size is assessed the same. Worse weather condition, wind directions, and ignition probabilities are considered.

Frequency Analysis – Initiating Event

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Failure Rates(per year /C )

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2-in

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4-in

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20-in

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0.75 2.0E-3 1.1E-2 1.1E-3 1.4E-3 9.6E-6 7.0E-6 4.6E-6 3.7E-6 3.1E-6 2.9E-6 2.8E-6 1.8E-3 9.8E-6 1.0E-3 7.2E-4 7.4E-4

2 8.5E-4 3.8E-3 3.9E-4 7.5E-4 0.0E+ 0 3.0E-7 2.1E-6 1.6E-6 1.5E-6 1.4E-6 1.2E-6 5.5E-4 5.5E-6 5.2E-4 3.7E-4 3.8E-4

6 2 2E-4 7 5E-4 8 3E-5 2 6E-4 0 0E+ 0 0 0E+0 0 0E+0 1 8E-7 4 3E-7 4 0E-7 2 8E-7 1 3E-4 1 3E-6 1 1E-4 7 9E-5 8 1E-5

/Component)

6 2.2E 4 7.5E 4 8.3E 5 2.6E 4 0.0E+ 0 0.0E+0 0.0E+0 1.8E 7 4.3E 7 4.0E 7 2.8E 7 1.3E 4 1.3E 6 1.1E 4 7.9E 5 8.1E 5

m

p. p. mp p

lineal feet of pipe

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Equipment count for

1-in

dia

2-in

dia

3-4i

n di

a

6-8i

n di

a

10-1

2in

dia

14-in

dia

20-in

dia

BFLP-01-T4201-ethy-top 100 1 1BFLP-02-T4201-mixT6201bot 1000 1 1

Source Cen

trif.

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each release source

BFLP-03-D4201-ethy 1 500 1BFLP-04-Cxxx-Propy 1 1000 1 1BFLP-05-T4801-Propy-bot 100 1 1BFLP-06-T4801-Propy-top 1 1000 1Sab-01-T6201-ethy-top 100 1 1Sab-02-T6201-mixT6201bot 1 1000 1Sab 03 D6201 eth 1 500 1Sab-03-D6201-ethy 1 500 1Sab-04-D6301-Propy 1 500 1Sab-05-C5401 1 1000 1 1Sab-06-TK9811-Butadi 1 1000 1Toxic-Sab-05-C5401 1 1000 1 1

Discharge Modelingg g Input

Storage Conditions• Type of storage

– Pressurized Gas– Liquefied Gas– Refrigerated Liquidg q– Liquid at Atmospheric temp and pressure

• Temp and Pressure of the material • Material Composition • Type of leak• Type of leak

– hole, tank rupture, pipe rupture Temperature and Pressure outside the tank

Output Discharge Rate Quantity Released or Duration The phase of a release and flash fraction The geometry of the release after expansion The geometry of the release after expansion Velocity of the release

Examples of Released Phase

Liquid Discharge Hole in atmospheric storage tank or pipe under Hole in atmospheric storage tank or pipe under

liquid head Hole in vessel or pipe containing pressurized liquid

b l it l b ili i tbelow its normal boiling point Gas Discharge Hole in equipment containing gas under pressure Hole in equipment containing gas under pressure Boiling-off evaporation from liquid pool Relief valve discharge from top of pressurized

storage tank Two-phase Discharge Hole in pressurized storage tank or pipe containing Hole in pressurized storage tank or pipe containing

a liquid above its normal boiling point

COMPUTING THE BLAST LOADCOMPUTING THE BLAST LOAD

Explosion Analysis Model

Need to include in the model: Potential sources – Defined in scenarios Zones of congestion and confinement

• BST Mapped by on site evaluation• BST - Mapped by on-site evaluation• CFD – Use of 3-D Solid Modeling

Locations of buildings used to calculate incident and reflected pressures and impulses.

Need pressure, impulse, and wave shape to predict building response Shock wavespredict building response. – Shock waves assumed in most cases – but this is changing.

Explosion Analysis

Flammable Vapor Cloud

Contours of Blast Overpressure or Building Damage LevelBuilding Damage Level

Source vs. Damage Locationg

OccupiedOccupiedBuildings

Source

©2007 Baker Engineering and Risk Consultants, Inc.

Mina Al-Ahmadi Refinery, Kuwait, 2000, 4 fatalities.

STRUCTURAL ASSESSMENTSTRUCTURAL ASSESSMENT

Blast Resistant Design vs Conventional Design

Conventional Blast ResistantDesign Basis Defined by:

•Use•CodesConsistent among owners

ithi ifi

Defined by risk:•Implied, or•Explicitly calculatedDiffers widely among owners.

within a specific area.Structural Performance

Expected to resist normal service loads indefinitely.

Varies with “Level of Protection”.

Design Structure remains elastic, Plastic deformations typically Approach includes safety factors:

•Allowable stress design•LRFD design

allowed:•Strength Increase Factors•Dynamic Increase Factors

Static analysis used even Dynamic analysis common.for dynamic loads. “Static Equivalent Loads”

discouraged.

Example of Acceptable Performance (non – Load Bearing)

Levels of Protection

Varies with intended use and client philosophySelect severe threat or accident scenarios and

flow level of protectionSelect median or average threats and provide

medium levels of protectionmedium levels of protectionSelect “common” accident or threat and

provide high levels of protectionUse quantitative risk approach

Once an LOP has been selected it be tied to building damage levels

Response Criteria

Response criteria set the amount of deformation t da component can undergo.

Response criteria per ASCE, and CIA is in terms of ductility and support rotations. High response y pp g pcorresponds to incipient failure. Ductility is maximum deflection / deflection at yield. Edge rotations defined next slideg

Response criteria per API (off-shore) is in terms of peak strain.

Models used to calculate these may be: Models used to calculate these may be: Single–Degree-of-Freedom (SDOF) Multiple-Degree-of Freedom (MDOF)

Fi it El t A l i Finite Element Analysis

Support Rotations

= Support Rotation

L

x

xm

Lxm2tan 1

Ltan

ASCE Component Response Levels

Component Damage or Response Level Component Consequence

Low Onset of visible damage; component can be repairedLow Onset of visible damage; component can be repaired.Medium Permanent deformation of components requiring replacement.

High Substantial plastic deformation approaching incipient collapse. Replacement is required. Component failure is possible, g p q p p ,although not probable, especially near the upper bound.

Failure Complete failure of component creating debris hazard. Replacement required.

ASCE Response Criteria

Upper Bound Criteria For Response Or Damage Levels

Low Medium High Element Type

Beams, Girts, Purlins 3 2 10 6 20 12

Frame Members 1.5 1 2 1.5 3 2

Cold-Formed Panels 1.75 1.25 3 2 6 4

Open-Web Joists 1 1 2 1.5 4 2

Plates 5 3 10 6 20 12Failure occurs when the upper bound of the High Response Level is exceeded.

Medium is typically the maximum acceptable response for design.

ERC – BakerRisk Building Damage LevelsLevels

ERC tool (BEAST) predict a Building ( ) p gDamage Level BDL1 – MinorBDL2a or BDL2 – Light Moderate or LightBDL2b or BDL2.5 – Heavy Moderate or

ModerateBDL3 - Major

BDL4 C llBDL4 – CollapseBDL can also be based on component

responses with emphasis on load bearingresponses with emphasis on load bearing walls and roof response.

US Corps of Engineers Damage Levels

1 – AT Standards refers to AntiTerrorism Standards1 AT Standards refers to AntiTerrorism Standards

Comparison of Damage Criteria

ERC – IndustryDamage Level

US Army COE Damage Level

Approximate Level of g g

Protection Provided

1 Superficial HighDamage

2a RepairableDamage

High - Medium

2b Unrepairable Damage

Medium - Low

3 Heavy Damage Very Low4 Severe Damage

or FailureVery Low to None

Building Damage 1 (Minor)

Load Bearing Masonry g yBuilding

Pre-engineered Metal BuildingPre engineered Metal Building

Building Damage 2a (Moderate)



Building Damage 2b (Heavy-Moderate)



Trailer Damage Level 2B

Building Damage 3 (Major)



Occupant Vulnerability For Different Building TypesTypes

100Bldg 1

Bldg 2

60

80

ity (%

) Bldg 3

Bldg 4

20

40

ulne

rabi

l Bldg 5

Bldg 7

Bldg 8

0

20Vu Bldg 8

Bldg 9

Bldg 100 1 2 3 4

Building Damage Level

Bldg 10

Bldg 11

Bldg 12

Example of Pressure-impulse (P-i) CurveCurve

P-I curves represent a suite of blast ploadings that will result in the same deformation of a structure.

By setting the deformation value to the bounds for damage levels the curves can b d I Dbe used as Iso-Damage curves.

Example Generic Scaled P-i Curve

Example of Component Specific P-i CurveCurve

Example US DDESB Curve

690 kPa -kPa ms

69 kPa

Building Siting Tools

Several proprietary tools:p p yBEASTSHEPPARD

US Department of Defense Explosives Safety Board (DDESB) has published building level P-i diagrams for limited suite of buildings

Design and Assessment Tools Available Finite Element Analysis is becoming more widely

used but simpler methods still dominate design. Simplified Tools developed by BakerRisk for the

COE and proprietary purposes: Integrated Structural Analysis and Design Integrated Structural Analysis and Design

Spreadsheet (ISADS) (Proprietary)• SDOF and 2DOF Capabilities• Pull down menus for components

Concrete Masonry Unit (CMU) Upgrade Tool (Proprietary)(Proprietary)

SBEDS – Developed for COEWBiggs – SDOF (Proprietary)ggs S O ( op eta y)

LS-DYNA Model of Motor Control Center

MCC is three story steel structure with two typesstructure with two types of walls Blast resistant walls on first

two levels on two sides Crimped plate walls on

other sides Model Parameters

3 in Shell Elements 3-in Shell Elements 422,057 Node 399,037 Elements

FEA of Off Shore MCC

MITIGATIONMITIGATION

Mitigation Measures

What can be done to protect occupants p p(control risk) if the existing building performance is unacceptable?

Hierarchy of Mitigation Measures Eliminate the hazard PASSIVE

Prevent release – upgrade design Control size of scenario – reduce inventory Mitigate Effects to Building Occupantsg g p

• Relocate them• Harden the building

ACTIVE Prevent release – Safety instrumented systems Control size of scenario – ESD systems Mitigate Effects to Building Occupants – HVAC g g

PROCEDURAL Prevent release – permits, inspections, LO/TO Control size of scenario – manual firefightingg g Mitigate Effects to Building Occupants - evacuate

BakerRisk Shock Tube

47

Loading Range For BakerRisk Shock Tube (10’ x 10’ Maximum Target)Tube (10 x 10 Maximum Target)

50

k

35

40

45

si)

310 kPa

15

20

25

30

Pres

sure

(ps Pressure and impulse can be

varied independently within boundaries shown.

6900 kPa - ms

0

5

10

15

0 200 400 600 800 1000 1200

Impulse (psi-mse)

Test of CMU WallBefore UpgradeBefore Upgrade


Test of CMU Wall Before Upgradef f pg

Upgrade to CMU WallUpgrade to CMU Wall

Steel Tube Reinforcement on Loaded Sideon Loaded Side

of CMU Wall


Test of Upgraded CMU Wall


Examples of Post Upgrades in the FieldField

New Exterior Posts and AnglesNew Exterior Posts and Angles

New Door Frame for Blast Resistant Door

Government R&D Program- Polyurea Catch Systems for Masonry and Glazing UnitsSystems for Masonry and Glazing Units

Test in Shock Tube LS-DYNA Analysis

Conducted for Sherwin Williams, funded by the US Air F

55

Force

Additional Upgrade Examples

Modifications to “Pre-Engineered” steel gbuildings

Roof upgradesDoor strengtheningWood trailer reinforcement

Example of Metal Building Upgrades

New wall girtsNew wall girts

N T dd d t f

New Stiffeners added to fram

New Tees added to frames

Example of Roof Strengthening

New purlins (grey)

Example of Wood Trailer StrengtheningStrengthening

New steel panels dd d tadded to

strengthen walls. T il b i Trailers being

prepped for attachment of steelattachment of steel panels.

Steel PanelsSteel Panels added.

Upgrade of Conventional Hollow Metal DoorsDoors

Experimentally validated method for enhancing strength of conventional hollow metal door.strength of conventional hollow metal door.Existing door at 3 psi (21 kPA)

Upgraded door at 4 psi (28 kPa)

60

Example of Door Strengthening

Typical Existing Door Retrofitted Door

Monolithic Window Test

High speed video of window test g pconducted at BakerRisk shock tube facility

Window 50 in x 68 in, ¼” annealed glass 1.25 m x 1.7 m x 6 mm

Blast Load ~ 4 psi, 60 psi-ms28 kPa, 410 kPa-ms

Window fails in “High Hazard Mode”Note formation of glass fragments

Monolithic Window Test

Laminated Window

Window test conducted at BakerRisk shock tube facility

Blast Load ~ 5 psi, 60 psi-msec (35 kPa, 410 kPa-ms)

Window passes in “Minimal Hazard Mode”

Laminated Window Test

Summary and Conclusions

Blast resistant design allows for damage to the structure. Flexibility and ductility more important than

rigidity and strengthrigidity and strength A clear understanding of the desired level of

protection is required. Existing structures can be readily hardened or

upgraded. Wi d d d i t t Windows and doors are important. Use of Static Equivalent Loads generally

discouraged.discouraged.

Blast and Eplosion Effects on Fixed and Portable Structures - Raymond Bennett

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Transcript of Blast and Eplosion Effects on Fixed and Portable Structures - Raymond Bennett