Hunter Bldg Test 2008

8/8/2019 Hunter Bldg Test 2008

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ABSG Consulting Inc. 14607 San Pedro Avenue, Suite 215 San Antonio, TX 78232 USA

Tel: 210-495-5195 Fax: 210-495-5134

www.absconsulting.com

1

Hunter Building and Manufacturing

Standard BuildingFull Scale Explosive Testing

Prepared For:

Hunter Buildings and Manufacturing

Houston, TX

Final Report

Project Number 1749999

Prepared By:

Ben Harrison, P.E.

Darrell Barker, P.E.

Jerry Collinsworth

July 9, 2008


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Standard Building Full Scale Explosive Testing, Final Report July 9, 2008

Hunter Buildings and Manufacturing Project No. 174999

i

Executive Summary

ABS Consulting conducted two full scale field tests utilizing 1,250 pounds of ANFO explosive

on a standard 8 psi, 200 msec Heavy Response Hunter blast resistant modular building. The

purpose of the explosive testing was to determine performance of the building at the upper limitof Medium Response (Test I) and the upper limit of High Response (Test II). Testing consisted

of the detonation of a 1,250 lbANFO charge at a range of 100 feet for Test I and 75 feet for Test II.

The ANFO charge was placed on the door side of the building for Test I and the opposite wall

for Test II. Peak side-on pressures were 9.7 psi for Test I and 17.4 psi for Test II.

Test I - Medium Response

Performance of the structure in Test I was consistent with ASCE Medium Response. While

primary components exhibited some plastic deformation, structural integrity was not

compromised. Test I resulted in a peak wall panel deformation of 6.3 inches which corresponds

to 6 degrees of support rotation, consistent with ASCE Medium Response limits for steel plates.Material strain data was not collected during the test but post-test evaluation of the response

indicated peak strains on the order of 4% which is also consistent with the selected design strain

limit for ASCE Medium Response. Peak wall accelerations were approximately 400 g. Peakbuilding sliding varied between 2 and 3 inches with a peak sliding acceleration of approximately

25g. Tipping was not observed.

An instrumented Hybrid III 50th percentile male car crash dummy was placed in the building for

Test I with the back of the Hybrid IIIs chair placed against the reflected wall. The peak

acceleration measured in the Hybrid III was 8 g. This acceleration is due to overall building

movement with some decoupling provided by the chair. Although the Hybrid III was situated

directly against the reflected wall only of the peak kinematic building acceleration wastransmitted to the Hybrid III. Relatively light damage was observed inside the building. Interior

furnishings and suspended items were dislodged. Acoustical ceiling tiles were down in some

sections of the building. The main ceiling grid components remained intact, but some of the

ceiling grid cross members were dislodged. Items placed on shelves were dislodged. Two fireextinguishers located on the blast wall came free from the mounting brackets.

Blast doors manufactured by Booth Industries were installed on the reflected wall facing theblast in Test I. Door latches were damaged during the test. One door rebounded open during the

test and the other door was jammed in the opening; therefore, the doors were found to be Intact

but Inoperable. There was no apparent structural deformation of the door beams. Hunter hasbeen manufacturing and installing its own blast doors which have been analyzed in separate

evaluation and testing.


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ii

Test II - High Response

Test II resulted in approximately 17.5 inches of deformation on the wall facing the blast as

integrated from the reflected wall accelerometer. Peak measured acceleration on the wall was onthe order of 2,000 g. Post-test evaluation indicated peak strains on the order of 10% which is

below the 15% value used for design. The peak wall deformation of 17.5 inches corresponds toa support rotation of 17 degrees. This response exceeds the ASCE support rotation limits forHigh Response for plates (12 degrees); however, damage to the structure was less than the

qualitative building damage description for High Response in the ASCE guideline. While

significant deformation occurred, the primary components were not at incipient collapse andwere not in danger of collapsing under environment loads (wind, etc.) as described by the ASCE

guideline for High response. Interior objects from the reflected wall including the desk, shelf,

cabinets and drywall had significant movement. The high debris velocity was evidenced by

penetrating impacts of desk coping into the veneer of the interior doors. The instrumenteddummy was not used for this test.

Both Booth blast doors on the rear face of the building, away from the charge, rebounded openduring Test II; however, the latches on the doors were damaged in Test I and thus did not have

the restraining capacity of an undamaged door.

Pressures were measured inside the building and were 3.7 psi during Test I and 4.5 psi during

Test II. Interior pressures did not appear to be the result of blast infiltration into the building but

may be attributed to the deformation of structural components. Sliding during Test II variedfrom 13-20 inches at the corners. Tipping was not observed in the high speed video.

Analysis of Results

Post-test modeling of the structure revealed that it was more flexible than predicted in theoriginal building analysis due to eave strut deformation. A revised model was prepared whichbetter matched the test results. This model results in greater wall deformation and support

rotation than the original analysis for the same strain value.

For Test I, the observed deflections were consistent with strain and rotation limits for Medium

Response in the ASCE guideline.

For Test II, deformations were less than High Response based on strain limits but observed

deformations were greater than High Response for support rotation limits. Thus if the design is

based on strain limits, deflections at maximum capacity will be greater than observed in the test.

If the design is based on support rotation, response at maximum capacity will be less thanobserved in the test.

Designing to the ASCE Building Damage descriptions in Table 5.B utilizing stain limits for thewall panels can be an appropriate approach; however, design based on support rotation limits is a

more common approach. In either approach, it is important for the user to understand the

deformations associated with the design and determine which is appropriate for the intended use.


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The utilization of support rotations is incorporated in blast design as a simplified measure ofdamage. However, with the advent of more powerful computing and modeling techniques more

sophisticated measures of damage may be utilized. This includes the use of plastic strain, rather

than support rotation response criteria. Plastic strains occur as a component is deformed beyondits elastic capacity. The amount of deformation required to cause a given amount of plastic

strain is a function of several variables, many of which can be non-linear. Examples of variablesthat affect the level of plasticity and deformation a component can withstand include the materialproperties, level of fixity provided at the component supports and the stability of the cross-

section.

Using strain limits, a revised structural model based on the test, and incorporating clearingeffects, the free-field blast capacity at the limit of High Response is consistent with the 8 psi

value. For a design based on ASCE support rotation limit criteria and including clearing, the

free-field blast capacity at High Response is 7.3 psi with the short wall facing the blast and 8.0psi with the long wall facing the blast.

Using strain limits, with the revised structural model based on the test and incorporating clearingeffects, the free-field blast capacity at the limit of Medium response is consistent with the 5.6 psi

value. For a design based on ASCE support rotation limit criteria and including clearing, the

free-field blast capacity at Medium Response is 5.9 psi, which is consistent with the design

value.

When selecting the appropriate response level and design criteria, vulnerability of occupants to

debris and dislodged objects should be considered in addition to the response of structuralcomponents. Assessment of vulnerability was beyond the scope of this test program.

If the Booth blast doors are used, at least one should be facing away from a potential blast.

/


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iv

Executive Summary......................................................................................................................... i

List of Figures................................................................................................................................. v

List of Tables ................................................................................................................................ vii1. Purpose.................................................................................................................................... 1

2. Building Layout and Construction.......................................................................................... 13. Test Configurations................................................................................................................. 33.1. Explosive Charge Siting ................................................................................................. 4

3.2. Instrumentation ............................................................................................................... 5

3.3. Test I Configuration...................................................................................................... 10

3.3.1. Range and Explosive Charge................................................................................ 103.3.2. Building Instrumentation Placement..................................................................... 12

3.4. Test II Configuration..................................................................................................... 17

3.4.1. Range and Explosive Charge................................................................................ 173.4.2. Building Instrumentation Placement..................................................................... 18

4. Test I Results......................................................................................................................... 22

4.1. Free Field and Applied Pressures ................................................................................. 224.2. Observed Damage......................................................................................................... 27

4.3. Structural Response Measurements .............................................................................. 38

4.3.1. Sliding and Tipping............................................................................................... 39

4.3.2. Wall Panel............................................................................................................. 404.3.3. Roof Joists............................................................................................................. 42

5. Test II Results ....................................................................................................................... 43

5.1. Free Field and Applied Pressures ................................................................................. 435.2. Observed Damage......................................................................................................... 48

5.3. Structural Response Measurements .............................................................................. 555.3.1. Sliding and Tipping Response .............................................................................. 56

5.3.2. Wall Panel Response............................................................................................. 57

5.3.3. End Wall Eave Strut Response ............................................................................. 596. Summary............................................................................................................................... 60


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v

List of Figures

Figure 1. Hunter Building Floor Plan ............................................................................................ 1

Figure 2. Hunter Building Exterior Elevations .............................................................................. 2Figure 3. Test Building Framing Plans and Framing Elevations................................................... 3

Figure 5. PCB 102A07 Pressure Transducer ................................................................................. 5Figure 6. Typical Reflected Pressure Gauge Mount...................................................................... 6Figure 7. PCB 350B23 Shock Accelerometer ............................................................................... 6

Figure 8. Wall Typical Accelerometer Mount............................................................................... 7

Figure 9. Sliding and Tipping Accelerometer Mount.................................................................... 7Figure 10. HYBRID III 50th Percentile Male Crash Test Dummy................................................ 8

Figure 11. Yokogawa DL750 Oscilloscope................................................................................... 9

Figure 12. Instrumentation Bunker................................................................................................ 9Figure 13. Concrete Footing and Spray Paint Marker ................................................................. 10

Figure 14. Test I - Range Layout................................................................................................. 11

Figure 15. Test I - Skirted Building............................................................................................. 11

Figure 16. Test I - Explosive Charge........................................................................................... 12Figure 17. Test I - Building Layout Relative to Explosive Charge ............................................. 13

Figure 18. Test I - Reflected Wall Instrumentation (Elevation 2) ............................................... 13

Figure 19. Test I - Rear Wall Instrumentation (Elevation 1)....................................................... 14Figure 20. Test I - Sidewall Instrumentation (Elevation 3) ......................................................... 14

Figure 21. Test I - Roof Instrumentation ..................................................................................... 15

Figure 22. Test I - Instrumented Hybrid III Placement ............................................................... 16Figure 23. Test I - Interior Cameras and Instrumentation ........................................................... 16

Figure 24. Test II - Explosive Charge.......................................................................................... 17

Figure 25. Test II - Unskirted Building ....................................................................................... 18

Figure 26. Test II - Range Layout................................................................................................ 18

Figure 27. Test II - Building Layout Relative to Explosive Charge............................................ 19Figure 28. Test II - Reflected Wall Instrumentation (Elevation 1).............................................. 19

Figure 29. Test II - Rear Wall Instrumentation (Elevation 2)...................................................... 20

Figure 30. Test II - Sidewall Instrumentation (Elevation 3)........................................................ 20

Figure 31. Test II - Roof Instrumentation.................................................................................... 21Figure 32. Test II - Interior Cameras and Instrumentation .......................................................... 21

Figure 33. Test I Crater................................................................................................................ 22

Figure 34. Test I - Free-Field Pressure Time History.................................................................. 23Figure 35. Test I - Reflected Wall Pressure Time History #1 ...................................................... 24

Figure 36. Test I - Reflected Wall Pressure Time History #2 ...................................................... 24

Figure 37. Test I- Applied Roof Pressure Time History.............................................................. 25Figure 38. Test I - Applied Rear Wall Pressure History.............................................................. 25

Figure 39. Test I - Interior Pressure Time History (Occupied Volume)...................................... 26

Figure 40. Test I - Interior Pressure Time History (Plenum)....................................................... 26

Figure 41. Test I - Reflected Wall Damage (Weld Cracks Spray Painted Magenta) .................. 28Figure 42. Test I - Rear Wall Damage......................................................................................... 28

Figure 43. Test I - Roof Damage ................................................................................................. 29

Figure 44. Test I - Passive Building Sliding Measurements........................................................ 30Figure 45. Test I - Damage to HVAC: (a) Exterior and (b) Interior........................................... 31


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Figure 46. Test I - Booth Blast Door Response: (a) Leftmost Door and (b) Rightmost Door ... 32Figure 47. Test I - Booth Door Latch Damage: (a) Pre-Test and (b) Post-Test ......................... 32

Figure 48. Test I - HYBRID III: (a) Pre-Test and (b) Post-Test................................................. 33

Figure 49. Test I - HYBRID III Measured Accelerations ........................................................... 34Figure 50. Test I - Mannequin: (a) Pre-Test and (b) Post-Test.................................................. 35

Figure 51. Test I - Building Interior: (a) Pre-Test and (b) Post-Test Damage............................ 35Figure 52. Test I - Cabinet Movement on Reflected Wall........................................................... 36Figure 53. Test I - Lavatory Fixtures: (a) Pre-Test and (b) Post-Test Damage.......................... 36

Figure 54. Test I - Interior Wall Damage: (a) Drywall Pulling Away and (b) Metal Stud

Damage ................................................................................................................................. 37

Figure 55. Test I - Fire Extinguisher Throw................................................................................ 38Figure 56. Test I Measured Sliding Time History .................................................................... 39

Figure 57. Test I - Measured Tipping Time History.................................................................... 40

Figure 58. Test I - Total Wall Panel Response Time History (Includes Sliding)........................ 41Figure 59. Test I - Relative Wall Panel Response Time History................................................. 41

Figure 60. Test I - Roof Joist Response Time History ................................................................ 42

Figure 61. Test II Crater............................................................................................................... 43Figure 62. Test II - Free-Field Pressure Time History................................................................. 44

Figure 63. Test II - Reflected Wall Pressure Time History #1.................................................... 45

Figure 64. Test II - Reflected Wall Pressure Time History #2.................................................... 45

Figure 65. Test II - Applied Roof Pressure Time History ........................................................... 46Figure 66. Test II - Applied Rear Wall Applied Pressure Time History ..................................... 46

Figure 67. Test II - Interior Pressure Time History (Occupied Volume) .................................... 47

Figure 68. Test II - Interior Pressure Time History (Plenum) ..................................................... 47Figure 69. Test II - High Speed Video Capture of Peak Wall Panel Response........................... 48

Figure 70. Test II - Reflected Wall Damage................................................................................ 49Figure 71. Test II - End Wall Damage......................................................................................... 49

Figure 72. Test II - Roof Deck Damage ...................................................................................... 50

Figure 73. Test II - Floor Deck Damage...................................................................................... 50Figure 74. Test II - Passive Building Sliding Measurements ...................................................... 51

Figure 75. Test II - Damage to HVAC: (a) Exterior and (b) Interior ......................................... 52

Figure 76. Test II - Damage to HVAC Duct................................................................................ 52Figure 77. Test II - Office Room: (a) Pre-Test and (b) Post- Test............................................. 53

Figure 78. Test II - Desk Debris Impacts: (a) Door Scarring and (b) With Impacting Debris ... 53

Figure 79. Test II - Central Work Room: (a) Pre-Test and (b) Post Test ................................... 54

Figure 80. Test II - Interior Debris............................................................................................... 54Figure 81. Test II - Light Fixture Damage................................................................................... 55

Figure 82. Test II - Measured Sliding Time History ................................................................... 56

Figure 83. Test II - Measured Tipping Time History .................................................................. 57Figure 84. Test II - Total Wall Panel Response Time History (Includes Sliding)....................... 58

Figure 85. Test II - Relative Wall Panel Response Time History ............................................... 58

Figure 86. Test II - End Wall Eave Strut Response Time History .............................................. 59


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vii

List of Tables

Table 1. Test Structure Component Cut List ................................................................................. 2Table 2. ASCE Response Range Descriptions .............................................................................. 4

Table 3. Test I - Deformation Limits............................................................................................. 4Table 4. Test II - Deformation Limits............................................................................................ 5Table 5. Test I - Measured and Applied Load Summary............................................................. 23

Table 6. Test I - Measured Response Summary .......................................................................... 39

Table 7. Test II - Measured and Applied Load Summary ........................................................... 44Table 8. Test II - Measured Response Summary......................................................................... 55


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1. Purpose

Hunter Buildings and Manufacturing LLC. (Hunter) manufactures blast resistant portable

buildings for the petroleum and chemical process industries. The purpose of a blast resistantmodular building is to provide increased protection to occupants over that which would be

provided by portable trailers of conventional construction.

Hunter Buildings contracted ABSG Consulting Inc (ABS Consulting) to perform two full scale

tests utilizing 1,250 pounds of ANFO. The purpose of the explosive testing was to test the

design and manufacturing of Hunter Buildings standard building at the upper limit of MediumResponse and the upper limit of High Response as defined by the American Society of Civil

Engineers (ASCE)Design of Blast Resistant Buildings in Petrochemical Facilities.[i]

2. Building Layout and Construction

The Hunter standard building utilized in the test measured 40 feet by 12 feet in plan and had an

eave height of 11 feet. A floor plan of the tested building is shown below in Figure 1 and

exterior elevations are provided in Figure 2. The building was constructed with the componentsshown in the framing plans and elevations in Figure 3 and specified in the cut list presented in

Table 1. Blast doors were manufactured by Booth Industries.

Figure 1. Hunter Building Floor Plan

i ASCE, Design of Blast Resistant Buildings in Petrochemical Facilities, Task Committee on Blast Resistant

Design, American Society of Civil Engineers, NY, NY, 1997.


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Figure 2. Hunter Building Exterior Elevations

Table 1. Test Structure Component Cut ListItem DimensionsTolerance No. of Pieces

CL1 HSS 6 x 6 x .625 A500B 11'-2" +0/-.125 4

CL2 HSS 6 x 6 x .500 A500B 10'-0" +0/-.125 7

B1 HSS 6 x 6 x .500 A500B 39'-0" +0/-.125 2

B2 HSS 6 x 6 x .500 A500B 11-0" +0/-.125 2

R1 HSS 6 x 6 x .500 A500B 39'-0" +0/-.125 2

R2 HSS 6 x 6 x .500 A500B 11'-0" +0/-.125 2

W1 HSS 6 x 6 x .500 A500B 3-0 +0/-.125 0

D1 HSS 6 x 6 x .500 A500B 3-1 1/2 +0/-.125 2

FJ1 HSS 6 x 2 x .3125 A500B 11'-0" +0/-.125 21

RJ1 C 6 x 13# A-36 11'-0" +0/-.125 19

RA1 Angle 2" x 2" x 1/8" A-36 39' +0/-.125 12

HRS 10 GA 17

HRS 12 GA 872" x 240"

84" x 120"

A1011-36

Description

A1011-36


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Figure 3. Test Building Framing Plans and Framing Elevations

3. Test Configurations

ABS Consulting tested a single standard Hunter Building two times. The building was not

manufactured specifically for this test but was pulled from the rental fleet at random. Therefore,

the building was representative of dimension, material, and fabrication of Hunters fleet ofbuildings and was not manufactured with the knowledge that it was for testing.

The purpose of Test I was to test the building at the upper limit of Medium Response in order tovalidate analysis methods and building response mechanisms. The purpose of Test II was to

determine potential failure mechanisms at the upper limits of capacity. Therefore, the building

was sited at a standoff predicted to cause a wall panel deformation at the upper limit of High

Response.

The following sections describe the instrumentation and instrumentation placement utilized to

achieve the goals for each test.


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3.1.Explosive Charge SitingThe goal of the test program was to perform two full scale high explosive tests utilizing 1,250 lbsof Ammonium Nitrate and Fuel Oil (ANFO). ANFO has a TNT equivalency of 0.82 for both

pressure and impulse which produces a TNT equivalent charge weight of 1,025 lbs TNT[ii]

. Thefirst explosive charge was configured to test the upper limit of Medium Response and the secondexperiment, with the charge placed on the opposite side of the structure, was configured to test

the upper limit of High Response. The design basis response levels are defined by ASCEs 1997

Design of Blast Resistant Buildings in Petrochemical Facilities[i]

. Response limits in Table 3were utilized for Test I and response limits in Table 4 were utilized for Test II. These support

rotation limits are more conservative than the strain limit criteria used for the design. Support

rotations were used because they are a more conservative approach and are commonly used inthe industry. Table 2 provides ASCEs written descriptions for the ASCE response levels. The

original design basis utilized these written descriptions and assigned strain limits to each

response level to quantify the design utilizing a strain limit of 7.5% for Medium Response and a

strain limit of 15% for High Response. A standoff of 100 ft was chosen for the first test and astandoff of 75 feet was chosen for the second test.

Table 2. ASCE Response Range DescriptionsResponse Range Description

Low

Localized building/component damage. Building can be used,

however repairs are required to restore integrity of structural envelope.Total cost of repairs is moderate.

Medium Widespread building/component damage. Building cannot be used

until repaired. Total cost of repairs is significant.

High Building/component has lost structural integrity and may collapse due

to environmental conditions. Total cost of repairs approach

replacement cost of building

Table 3. Test I - Deformation Limits

Test Target Deformation LimitComponent

(deg) (in)Wall Panel

*Designed for plasticity only and qualitativedescriptions in Table 2.

Roof and Floor Deck 6 10 1.2 in

Roof Joist 6 10 6.9 in

Floor Joist 6 10 6.9 in

End Wall Eave and

Sill Struts

6 10 6.9in

Door Column (Low) 2 3 2.1 in*Corrugated panel response criteria were not adopted as they were intended for thin gauge

(< 1/8-inch) panels. Plasticity limit criteria via FEA were utilized.

**Design of Columns supporting doors were limited to Low Response in order to aide

egress.

ii ConWep, Conventional Weapons Effects Program, Structures Laboratory, U.S. Army Engineer Waterways

Experiment Station, Vicksberg, Mississippi, V. 2.1.0.8.


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Table 4. Test II - Deformation Limits

Test Target Deformation LimitComponent

(deg) (in)Wall Panel* Designed for plasticity only and qualitative

descriptions in Table 2.Roof and Floor Deck 12 20 2.5 in

Roof Joist 12 20 14 in

Floor Joist 12 20 14 in

End Wall Eave and

Sill Struts

12 20 14 in

*Corrugated panel response criteria were not adopted as they were intended for thin gauge

(< 1/8-inch) panels. Plasticity limit criteria via FEA were utilized.

**Design of Columns supporting doors were limited to Low Response in order to aide

egress.

3.2.InstrumentationIn order to measure free-field and applied pressures nine PCB 102A07 pressure transducers, see

Figure 4, were utilized. These transducers measure pressure in the presence of shock and

vibration. The pressure probe consists of the Model 112A high sensitivity acceleration

compensated quartz element and an IC source follower amplifier joined together as aninseparable assembly and can measure pressures up to 50 psi utilizing 5 v output and has a useful

over range of 100 psi utilizing 10v output.

Figure 4. PCB 102A07 Pressure Transducer


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Figure 5. Typical Reflected Pressure Gauge Mount

Three PCB 350B23 accelerometers, see Figure 6, and one PCB 350B02 accelerometer wereutilized for structural response measurements. The equations of motion are characterized bythree main variables: acceleration, velocity and displacement and these three variables can be

mathematically derived from the measurements of acceleration. The PCB 350B02

Accelerometer has a range of 50,000 g and the PCB 350B23 accelerometers have a range of

10,000 g. The accelerometers are characterized by the following features:

Fixed voltage sensitivity, regardless of cable type.

Low-impedance output signal, which can be transmitted over long cables in harshenvironments with virtually no loss in signal quality.

Two-wire operation with low cost coaxial cable.

Requires only constant current signal conditioning.

Figure 6. PCB 350B23 Shock Accelerometer


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Figure 7. Wall Typical Accelerometer Mount

Figure 8. Sliding and Tipping Accelerometer Mount

A HYBRID III 50th Percentile male crash test dummy, representing the average adult male, was

utilized to measure occupant response. The HYBRID III, see Figure 9, is the most widely used

dummy in frontal crash and automotive safety restraint testing. The Hybrid IIIs height is 5 feet

9 inches and weights 172.3 pounds. Originally, the Hybrid III 50th male was developed byGeneral Motors for vehicle safety purposes. It has since been incorporated into the Code of

Federal Regulations under Title 49, Part 572 subpart E, and is the required dummy in NHTSAsmotor vehicle safety standards. The Hybrid III 50th male features a neck design that simulates

the human dynamic moment / rotation, flexion, and extension response characteristics of an

average size adult male. The upper torso has 6 high strength steel ribs with polymer baseddamping material to simulate human chest force-deflection characteristics. The lower torso has a

curved cylindrical rubber lumbar spine that provide human-like slouch of a seated person. The


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pelvis is vinyl skin/urethane foam molded over an aluminum casting in the seated position. Theball-jointed femur attachments carry bump stops to reproduce the human leg to hip

moment/rotation characteristics.

The Hybrid III was instrumented with three piezo-resistive accelerometers in the head with one

in the vertical axis and two placed orthogonally in the horizontal plane, front to back and ear toear.

Figure 9. HYBRID III 50th

Percentile Male Crash Test Dummy

Instrumentation measurements were measured utilizing a Yokogawa DL750 Oscilloscope,

shown in Figure 10. The Oscilloscope is capable of recording up to sixteen channels at high data

sampling rates (i.e., > 1 MHz). Testing experience indicates that a sampling rate of at least 500KHz or 500 samples per millisecond for shock pressure histories and 300 kHz (or 300 samples

per millisecond) for acceleration time histories provides adequate fidelity for a structural

response. This ensures that very short duration peaks in shock pressure and accelerationmeasurements are not missed by the data recording process. In general, a sample rate of 500

KHz was used to record the test data when the Hybrid III was utilized and 1 MHz otherwise.The Yokogawa scope was placed within a bunker on the side of the building away from the

charge as shown in Figure 11.


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Figure 10. Yokogawa DL750 Oscilloscope

Figure 11. Instrumentation Bunker

The building was placed on concrete pads in order to more accurately assess the sliding response.

In addition to utilizing accelerometers to measure sliding, the building position was marked

using spray paint at each footing location as shown in Figure 12 so that the sliding distance could

be observed directly.


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Figure 12. Concrete Footing and Spray Paint Marker

3.3.Test I ConfigurationThe purpose of Test I was to test the building at the upper limit of Medium Response in order to

validate modeling methods and building response mechanisms. In order to achieve those goals

the explosive charge and instrumentation were arranged to produce the desired level of walldamage, to measure the applied loads to the building and the level of structural response.

3.3.1. Range and Explosive Charge

The test arena was arranged with two free-field pressure gauges and three high speed cameras as

shown in Figure 13. Free-field gauge #1 was placed in the shadow of the building from the

explosive charge and free-field gauge #2 was placed at an identical range to the charge as thebuilding to measure the free-field pressures associated with the applied building loads. The

explosive charge, Figure 15, was placed at a range of 100 ft from the center of the blastward wall

of the building. The three high speed cameras were placed further from the explosive chargethan the building so that the structural response could be recorded by the cameras before the

shockwave arrived at the camera locations.

For the first test, the building was skirted with 2x12 wood joists along the reflected wall to

prevent shock from traveling underneath the building. A photo of the skirted building is

provided in Test I - Skirted Building. By preventing shock from traveling under the building the

effects of the dynamic roof load on the friction force could be evaluated.


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Figure 13. Test I - Range Layout

Figure 14. Test I - Skirted Building


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Figure 15. Test I - Explosive Charge

3.3.2. Building Instrumentation Placement

The building was oriented such that the building elevation holding the two blast doors was facing

the charge as shown in Figure 16. Figure 16 also shows the numbering of the concrete footingsthe building was placed on for reference to passive sliding measurements. The reflected wall

was instrumented with two pressure gauges for measuring the applied reflected load, and three

accelerometers for measuring the wall panel response as well as the sliding and tipping response

of the building. The reflected wall instrumentation plan is provided below in Figure 17.


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100 ft

2

3

1

4

100 ft

22

33

11

44

Figure 16. Test I - Building Layout Relative to Explosive Charge

Pressure

Gauge

Pressure

Gauge

Wall Panel

Accelerometer

Sliding and TippingAccelerometers

Pressure

Gauge

Pressure

Gauge

Wall Panel

Accelerometer

Sliding and TippingAccelerometers

Figure 17. Test I - Reflected Wall Instrumentation (Elevation 2)

The leeward wall of the building was instrumented with a single pressure gauge to measure theapplied load to the backside of the building. An elevation of the back wall detailing the location

of the pressure gauge is provided in Figure 18.


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Pressure

Gauge

Pressure

Gauge

Figure 18. Test I - Rear Wall Instrumentation (Elevation 1)

The sidewall of the building opposite of the HVAC equipment was instrumented with a pressuregauge, as shown in Figure 19, in order to measure the applied pressure to the enwall of the

building.

Pressure

Gauge

Pressure

Gauge

Figure 19. Test I - Sidewall Instrumentation (Elevation 3)

The roof of the building was instrumented with a pressure gauge to measure the applied pressure

at the center of the roof. An accelerometer was placed at the mid-span of a roof joist so that the

response of the roof joist to the measured roof load could be evaluated. A detail of the roofinstrumentation plan is provided below in Figure 20.


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Pressure

Gauge

Accelerometer Pressure

Gauge

Accelerometer

Figure 20. Test I - Roof Instrumentation

Cameras and instruments were also placed within the building to assess the occupant

environment during structural response to the explosion. Three closed circuit cameras wereplaced inside the building along with an instrumented Hybrid III dummy (see Figure 21), amannequin and two pressure gauges. The Hybrid III was placed in a chair with the back of the

dummy and chair resting against the reflected wall. A plan showing the location of the cameras

and instruments is provided in Figure 22. As can be seen in Figure 22, the Hybrid III was placedaway from a column so that it could be impacted by the responding wall panel. One pressure

gauge was placed in the occupied volume of the building and a second was placed within the

plenum between the roof and drop ceiling so that any disparity of pressure between these twovolumes within the building could be evaluated.


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Figure 21. Test I - Instrumented Hybrid III Placement

Figure 22. Test I - Interior Cameras and Instrumentation


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3.4.Test II ConfigurationThe purpose of Test II was to test potential building failure mechanisms and damage at the upper

limits of High Response. In order to achieve those goals the explosive charge and

instrumentation were arranged to produce the desired level of wall damage, to measure theapplied loads to the building and the level of structural response.

3.4.1. Range and Explosive Charge

The test arena was arranged with two free-field pressure gauges and three high speed cameras as

shown in Figure 25. Free-field gauge #1 was placed in the shadow of the building from the

explosive charge and free-field gauge #2 was placed at an identical range to the charge as thebuilding to measure the free-field pressures associated with the applied building loads. The

explosive charge, Figure 23, was placed at a range of 75 ft from the center of the blastward wall

of the building. The three high speed cameras were placed further from the explosive chargethan the building so that the structural response could be recorded by the cameras before the

shockwave arrived at the camera locations.

For the first test, the building was skirted with 2x12 wood joists along the reflected wall to

prevent shock from traveling underneath the building. By preventing shock from traveling under

the building the effects of the dynamic roof load on the friction force could be evaluated.

Figure 23. Test II - Explosive Charge


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Figure 24. Test II - Unskirted Building

Figure 25. Test II - Range Layout

3.4.2. Building Instrumentation Placement

The building was oriented such that the building elevation holding the two blast doors was facingaway from the charge as shown in Figure 26. Figure 26 also shows the numbering of the

concrete footings the building was placed on for reference to passive sliding measurements. The

reflected wall was instrumented with two pressure gauges for measuring the applied reflectedload, and three accelerometers. One accelerometer was placed for measuring the wall panel


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19

response and two accelerometers for the sliding and tipping response of the building. Thereflected wall instrumentation plan is provided below in Figure 27.

75 ft

2

3

1

4

75 ft75 ft

22

33

11

44

Figure 26. Test II - Building Layout Relative to Explosive Charge

Pressure

Gauge

Wall Panel

Accelerometer

Sliding and Tipping

Accelerometers

Pressure

Gauge

Pressure

Gauge

Wall Panel

Accelerometer

Sliding and Tipping

Accelerometers

Pressure

Gauge

Figure 27. Test II - Reflected Wall Instrumentation (Elevation 1)


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The leeward wall of the building was instrumented with a single pressure gauge to measure theapplied load to the backside of the building. An elevation of the back wall detailing the location

of the pressure gauge is provided in Figure 28.

Pressure

Gauge

Pressure

Gauge

Figure 28. Test II - Rear Wall Instrumentation (Elevation 2)

The sidewall of the building opposite of the HVAC equipment was instrumented with a pressure

gauge and accelerometer, as shown in Figure 28. The pressure gauge measured the applied loadto the side wall and the accelerometer measured the flexural response of the eave strut.

Pressure

Gauge

Accelerometer

Pressure

Gauge

Pressure

Gauge

Accelerometer

Figure 29. Test II - Sidewall Instrumentation (Elevation 3)

The roof of the building was instrumented with a pressure gauge to measure the applied pressure

at the center of the roof as shown in the detail of the roof instrumentation plan provided below in

Figure 30.


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Pressure

Gauge

Pressure

Gauge

Figure 30. Test II - Roof Instrumentation

Cameras and instruments were also placed within the building to assess the occupant

environment during structural response to the explosion. Three closed circuit cameras wereplaced inside the building along with a mannequin and two pressure gauges. The Hybrid III was

not utilized for Test II due to the potential to damage the Hybrid III and instrumentation. A plan

showing the location of the cameras and instruments is provided in Figure 31. One pressure

gauge was placed in the occupied volume of the building and a second was placed within theplenum between the roof and drop ceiling so that any disparity of pressure between these two

volumes within the building could be evaluated. The mannequin was situated against the desk

along the reflected wall.

Figure 31. Test II - Interior Cameras and Instrumentation


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4. Test I Results

The first explosive test produced the crater shown below in Figure 32. The crater had an inner

diameter of 7 feet, an outer diameter of 15 feet and a depth of 38 inches. A summary of the blast

loading, observed pressure and structural response are provided in the following sections.

Figure 32. Test I Crater

4.1.Free Field and Applied PressuresThe measured free-field and applied pressures are summarized below in Table 5 with the

associated time histories in Figure 33 through Figure 39. The free-field and reflected peakpressures compared well to the theoretical values for 1,250 lbsANFO at 100 feet. The endwallpressure gauge failed and did not record a good trace. Of interest are the interior pressure

histories in Figure 38 and Figure 39. Peak pressures in the occupied volume peaked at 4 psi and

the plenum pressures were on the order of 1 psi. The interior pressures are not the result ofshock infiltrating the structure through openings. Instead they are a result of pressure waves

transmitted into the structure from deformation of the buildings surfaces (walls and roof).


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Table 5. Test I - Measured and Applied Load Summary

Peak Positive PhaseGauge

Pressure

(psi)

Impulse

(psi*msec)

PressureTime History

Free Field 9.6 51 Figure 33

Reflected Wall #1 24.0 154 Figure 34Reflected Wall #2 25.5 153 Figure 35

Roof 7.0 30 Figure 36

Rear Wall 3.0 59 Figure 37

Side Wall Gauge Failure

Interior Pressure

(Occupied Volume)

3.7 22 Figure 38

Interior Pressure(Plenum)

0.8 71 Figure 39

Time (msec)

Pressure(psi)

Im

pulse(psi-msec)

-40 -20 0 20 40 60 80 100 120-5 -20

0 0

5 20

10 40

15 60Raw DataFiltered Data (3.5-250hz)Impulse

Figure 33. Test I - Free-Field Pressure Time History


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Time (msec)

Pressure(psi)

Impulse(psi-msec)

-60 -40 -20 0 20 40 60 80 100 120 140-15 -60

-5 -20

5 20

15 60

25 100


Figure 34. Test I - Reflected Wall Pressure Time History #1

Time (msec)

Pressure(psi)

Impulse(psi-mse

c)

-75 -50 -25 0 25 50 75 100 125 150 175-30 -120

-20 -80

-10 -40

0 0

10 40

20 80

30 120

40 160Raw DataFiltered Data (4-500hz)Impulse

Figure 35. Test I - Reflected Wall Pressure Time History #2


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Time (msec)

Pressure(psi)

Impulse(psi-msec

)

-100 -75 -50 -25 0 25 50 75 100 125 150-4 -30

-2 -15

0 0

2 15

4 30

6 45

8 60Raw DataFiltered Data (1500hz)Impulse

Figure 36. Test I- Applied Roof Pressure Time History

Time (msec)

Pressure(ps

i)

Impulse(psi-m

sec)

-75 -50 -25 0 25 50 75 100 125 150 175

-15 -45

-10 -30

-5 -15

0 0

5 15

10 30

15 45

20 60

Raw DataFiltered Data (1.1-1000hz)Impulse

Figure 37. Test I - Applied Rear Wall Pressure History


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Time (msec)

Pressure(psi)

Impulse(psi-msec)

-25 0 25 50 75 100 125 150 175 200 225-7.5 -24

-5 -16

-2.5 -8

0 0

2.5 8

5 16

7.5 24

10 32

Raw DataFiltered Data (5.5-500hz)Impulse

Figure 38. Test I - Interior Pressure Time History (Occupied Volume)

Time (msec)

Pressure(ps

i)

Impulse(psi-msec)

-75 -50 -25 0 25 50 75 100 125 150 175

-2 -10

-1 -5

0 0

1 5

2 10

3 15

4 20


Figure 39. Test I - Interior Pressure Time History (Plenum)


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4.2.Observed DamageDamage to the Hunter Standard Building is characterized by the permanent deformation of

structural components such as wall panels and roof joists, sliding and tipping of the building, and

displacement of internal fixtures.

After Test I a permanent deflection of the reflected wall was measured to be between 3 and 4inches depending upon the location of the measurement. Reflected wall damage is shown in

Figure 40. Cracking of the wall panel supporting overhead welds along the top of the panel wereobserved and are highlighted by magenta paint in Figure 40. A total of five cracks, all on the

tension face of the panel, were observed with lengths of 1 inch, 13 inches, and 3.5 inches. The

total length of cracking was measured to be 34 inches. It is suspected, but not confirmed, thatthe cause of the cracking was improper fit up of the panel prior to welding. The suspected fit-up

issue would be caused by the panel sitting on the bottom tube and too large of a gap existing

between the top of the panel and the top tube. In this condition, the toe of the weld on the panelwould be insufficient. It is important to note that the weld cracks did not lead to any structural

failure or increased wall panel response when subjected to the test blast loading.

No permanent deformations of the side-wall or rear wall panels was visible and fieldmeasurements showed no permanent damage to these building surfaces. Figure 41 shows the

lack of damage to the rear wall after Test I.


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Figure 40. Test I - Reflected Wall Damage (Weld Cracks Spray Painted Magenta)

Figure 41. Test I - Rear Wall Damage


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The roof of the building sustained little damage as shown in Figure 42. There was no visible or

measurable permanent deformation to the roof joists. Roof panel deformations were measured

between 3/8 and 5/8 inches.

Figure 42. Test I - Roof Damage

Sliding of the building was measured actively utilizing an accelerometer and passively by spraypainting around the building base plates. After the first test the building slid between two and

three inches as shown in Figure 43.


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Figure 43. Test I - Passive Building Sliding Measurements

1

2

3

4

1

2

3

4


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31

The HVAC unit on the end wall of the building was damaged by the test and is shown in its posttest condition in Figure 44. The interior view of the HVAC shows that the air intake filter is still

in place. In addition no blowout of any of the ducts inside the building was observed.

Figure 44. Test I - Damage to HVAC: (a) Exterior and (b) Interior

The test building was fitted with doors provided by Booth Industries. Both doors were Intact butInoperable after the test as show in Figure 45. The doors were inoperable due to damage to the

latch plate on the door as shown in Figure 46. The rightmost door into the work room was blownopen during the negative phase of the explosion. The leftmost door in Figure 45 could not be

opened manually or with the application of force by sledge hammer. No permanent bending of

the door leaf was observed nor measured.

(a) (b)


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Figure 45. Test I - Booth Blast Door Response: (a) Leftmost Door and (b) Rightmost Door

Figure 46. Test I - Booth Door Latch Damage: (a) Pre-Test and (b) Post-Test

(a) (b)


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33

Simulated occupants, the Hybrid III and Mannequin, were moved by the explosion but were still

in their places. The Hybrid III, which was situated against the reflected wall, had obviously been

rotated slightly forward about the hips as shown in Figure 47. In the post test condition theHybrid IIIs feet are no longer pressed against the bathroom wall but are placed firmly to the

floor. In addition, the right arm of the Hybrid III was found to be resting against the chair andthe Hybrid IIIs torso had been rotated forward. Measurements from the Hybrid IIIaccelerometers are presented in Figure 48. The peak acceleration was from front to back on the

Hybrid III and measured approximately 8 g. For comparison, the peak acceleration of the

building from sliding was measured to be approximately 25 g. Although the Hybrid III was

situated directly against the reflected wall only of the peak kinematic building accelerationwas transmitted to the Hybrid III. Peak vertical acceleration measured in the Hybrid III was

approximately 2 g.

Figure 47. Test I - HYBRID III: (a) Pre-Test and (b) Post-Test

(a) (b)


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Time (msec)

Acceleration(g)

0 5 10 15 20 25 30 35 40 45 50 55 60 65-12.5

-10

-7.5

-5

-2.5

0

2.5

5

7.5

10Raw Data_Dummy 01 (Front and Back)Raw Data_Dummy 02 (Left and Right)Raw Data_Dummy 03 (Up and Down)

Figure 48. Test I - HYBRID III Measured Accelerations

The mannequin was placed at the desk situated along the rear wall of the building as shown in

Figure 49. The mannequin was held in place by a bungee cord around the waist of themannequin and fastened to the chair. The bungee cord is visible in Figure 49. After the test, the

mannequin was still in place in the chair. The mannequin was impacted by folders and books

that were placed along the shelf above the desk as wall as some of the framing for the acoustic

ceiling.


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Figure 49. Test I - Mannequin: (a) Pre-Test and (b) Post-Test

The damage to the interior of the building is summarized in Figure 50 through Figure 54. The

main work room is shown in Figure 50. Ceiling tiles and framing for the ceiling tiles were found

on the floor. All overhead fluorescent light fixtures were still in place as was the overhead

drywall insulation above the acoustic ceiling. The books placed on the shelf along the back wall

were thrown to the floor. The cabinet on the blastward wall was moved approximately 6 inchesaway from the reflected wall as highlighted in Figure 51.

Figure 50. Test I - Building Interior: (a) Pre-Test and (b) Post-Test Damage

(a) (b)

(a) (b)


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Figure 51. Test I - Cabinet Movement on Reflected Wall

The porcelain bathroom fixtures were shattered by the shock to the building, see Figure 52. The

sink had fallen to the floor from its mount and shattered as had the toilet. Several large shards of

porcelain from the sink and toilet were observed.

Figure 52. Test I - Lavatory Fixtures: (a) Pre-Test and (b) Post-Test Damage

The interior metal stud wall was impacted by the responding reflected wall and the steel studs

were bent inward permanently. Evidence of this damage, see Figure 53, could be seen aroundlight switches and plugs. A section of the interior wall panel was removed to reveal the damage

to the interior metal studs.

(a) (b)


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Figure 53. Test I - Interior Wall Damage: (a) Drywall Pulling Away and (b) Metal Stud

Damage

Two fire extinguishers were mounted to the blastward wall and both were thrown across the

building to the opposite wall. One fire extinguisher which was located in the end work room is

shown in Figure 54.

(a) (b)


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Figure 54. Test I - Fire Extinguisher Throw

4.3.Structural Response MeasurementsAs discussed in Section 3.3.2, the building was instrument to active record structuralaccelerations of sliding and tipping, the reflected wall panel and roof joist. The acceleration data

was filtered and integrated twice to produce displacement time histories. The wall panelaccelerometers recorded the kinematic sliding of the building in addition to the flexural responseof the wall panel. Therefore, the sliding response had to be subtracted from the wall panel

response in order to obtain the wall panel relative displacement time history. A summary of the

active response measurements are provided below in Table 6. The wall panel and building

response compared well to pretest predictions as evidenced by the 6 degree rotation of thereflected wall panel. The roof joist response was low, about 1 degree of support rotation. The

sliding response was recorded in building corner 1, see Figure 16. The recorded sliding response

of 1.7 inches compared well with the passive measurement at this corner of 2 inches.


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Table 6. Test I - Measured Response Summary

Measured ResponseComponent

max (in) (deg)Wall Panel

6.3 in 6.0

Roof Joist 1.2 in 1.0

Sliding* 1.7 in -

Tipping**

-* Sliding passive response measurements presented in Figure 43.** Tipping data is incomplete due to loss of signal during the test.

4.3.1. Sliding and Tipping

The sliding and tipping measurements experienced some drift of the signal at later times and the

tipping accelerometer measurements experienced a loss of signal for about 20 msec. The

acceleration and integrated sliding data are presented below in Figure 55. This data compared

well to the passive sliding measurement of the same building corner as was instrumented. Peak

sliding accelerations were on the order of 100 gs. The active tipping acceleration measurementscould not be evaluated due to loss of the signal as shown in Figure 56.

Time (msec)

Acc

eleration(in/msec^2)andVelocity(in/msec)

Displacement(in)

-12 -4 4 12 20 28 36 44-0.3 -10

-0.24 -8

-0.18 -6

-0.12 -4

-0.06 -2

0 0

0.06 2

0.12 4

0.18 6

0.24 8

0.3 10Raw Acceleration DataFiltered Acceleration DataVelocityDisplacement

Figure 55. Test I Measured Sliding Time History


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Time (msec)

Acceleration(in/msec^2)andVelocity(in/msec)

Displacement(in)

-12 -4 4 12 20 28 36 44-0.25 -60

-0.2 -30

-0.15 0

-0.1 30

-0.05 60

0 90

0.05 120

0.1 150

0.15 180

0.2 210Raw Data_1st halfRaw Data_2nd halfFiltered Data (1000hz)velocity

displacement

Figure 56. Test I - Measured Tipping Time History

4.3.2. Wall Panel

The wall panel acceleration time history and integrated data is presented below in Figure 57.

The peak acceleration of the wall panel including sliding was recorded to be approximately 400gs, which compares well to the theoretical peak acceleration. The accelerometer recorded boththe wall panel response and kinematic sliding. Therefore, in order to properly assess the panel

displacement time history, the sliding response must be subtracted. The relative wall panel

displacement time history is presented in Figure 58. The peak recorded wall displacement

relative to the supporting structural members was 6.3 inches. This displacement corresponds to asupport rotation of 6 degrees. The design limit for medium response was 6 degrees; therefore,

the response correlated well to the pre-test prediction.


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42

4.3.3. Roof Joists

The roof joist measured response time history is presented below in Figure 59. The peak roof

joist acceleration was approximately 160 gs. The peak displacement as integrated from the

acceleration time history was 1.2 inches which corresponds to a support rotation of 1 degree.

Time (msec)

Acceleration(in/msec

^2)andVelocity(in/msec)

Displacement(in)

-7.5 -2.5 2.5 7.5 12.5 17.5 22.5 27.5 32.5-0.48 -15

-0.32 -10

-0.16 -5

0 0

0.16 5

0.32 10

0.48 15


Figure 59. Test I - Roof Joist Response Time History


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5. Test II Results

The second explosive test produced the crater shown below in Figure 60. The crater had an innerdiameter of 7 feet, an outer diameter of 15 feet and a depth of 41 inches. A summary of the blast

loading, observed pressure and structural response are provided in the following sections.

Figure 60. Test II Crater

5.1.Free Field and Applied PressuresThe measured free-field and applied pressures are summarized below in Table 7 with the

associated time histories in Figure 61 through Figure 67. The free-field and reflected peakpressures were higher than the theoretical values for 1,250 lbsANFO at 75 feet but not

unreasonably so. The endwall pressure gauge failed and did not record a good trace. Of interest

are the interior pressure histories in Figure 66 and Figure 67. Peak pressures in the occupiedvolume peaked at 4.5 psi and the plenum pressures were on the order of 1.5 psi. The interior

pressures are not the result of shock infiltrating the structure through openings. Instead they are

a result of pressure waves transmitted into the structure from deformation of the buildings

surfaces (walls and roof).


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Table 7. Test II - Measured and Applied Load Summary

Peak Positive PhaseGauge

Pressure

(psi)

Impulse

(psi*msec)

PressureTime History

Free Field 23.5 62 Figure 61

Reflected Wall #1 77.9 248 Figure 62Reflected Wall #2 67.1 313 Figure 63

Roof 8.8 32 Figure 64

Rear Wall 5.5 70 Figure 65

Side Wall Gauge Failure

Interior Pressure

(Occupied Volume)

4.5 39 Figure 66

Interior Pressure(Occupied Volume)

1.4 24 Figure 67

Time (msec)

Pressure(psi)

Im

pulse(psi-msec)

-40 -20 0 20 40 60 80 100-10 -20

0 0

10 20

20 40

30 60

40 80Raw DataFiltered Data (6-2500hz)Impulse

Figure 61. Test II - Free-Field Pressure Time History


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Time (msec)

Pressure(psi)

Impulse(psi-msec

)

-4 -2 0 2 4 6 8 10 12 14-100 -0.8

-50 -0.4

0 0

50 0.4

100 0.8

150 1.2

200 1.6

250 2

300 2.4Raw DataImpulse

Figure 62. Test II - Reflected Wall Pressure Time History #1

Time (msec)

Pressure(psi)

Impulse(psi-msec

)

-10 -5 0 5 10 15 20-50 -400

0 0

50 400

100 800

150 1200Raw DataImpulse

Figure 63. Test II - Reflected Wall Pressure Time History #2


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Time (msec)

Pressure(psi)

Impulse(psi-msec

)

-40 -20 0 20 40 60 80 100 120-10 -30

-5 -15

0 0

5 15

10 30


Figure 64. Test II - Applied Roof Pressure Time History

Time (msec)

Pressure(ps

i)

Impulse(psi-msec)

-50 -25 0 25 50 75 100 125 150 175 200

-10 -80

-7.5 -60

-5 -40

-2.5 -20

0 0

2.5 20

5 40

7.5 60


Figure 65. Test II - Applied Rear Wall Applied Pressure Time History


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Time (msec)

Pressure(psi)

Impulse(psi-mse

c)

-20 0 20 40 60 80 100 120 140 160 180-15 -120

-10 -80

-5 -40

0 0

5 40

10 80

Raw DataFiltered Data (4-1000hz)Impulse

Figure 66. Test II - Interior Pressure Time History (Occupied Volume)

Time (msec)

Pressure(psi)

Impulse(psi-msec

)

-50 -25 0 25 50 75 100 125 150 175 200 225 250

-2 -20

-1.5 -15

-1 -10

-0.5 -5

0 0

0.5 5

1 10

1.5 15

2 20

2.5 25


Figure 67. Test II - Interior Pressure Time History (Plenum)


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5.2.Observed DamageDuring the second test the wall panels were pressed inward and developed in-plane tensile

membrane forces. This is evidenced in the high speed video image in Figure 68. The supportingHSS Eave Strut is bent between the columns from the panel tensile reaction. Unfolding and

flattening of the corrugations can also be seen. The post test condition of the reflected wall panelis shown in Figure 69. The panels were found to be pulled outward approximately 5 inches in

the middle with permanent inward deflections of approximately 8 inches to either side of theoutward panel bulge. No cracking of the reflected wall panel welds was observed after the

second test. Although significant demand was placed on the HSS eave strut at the peak wall

panel response as shown in Figure 68, no permanent downward deflection of the eave strut waspresent after the test.

The side wall panel was buckled and had a permanent inward deformation of 5/16 inches asshown in Figure 70.

Figure 68. Test II - High Speed Video Capture of Peak Wall Panel Response


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Figure 69. Test II - Reflected Wall Damage

Figure 70. Test II - End Wall Damage

Damage to the roof deck and roof joists after Test II, shown in Figure 71, was not measurablydifferent that that which was observed after Test I. Photographs of the underside of the buildingwere taken during the load out of the building and floor deck damage was observed as shown in

Figure 72. This is not unexpected since the building was not skirted for the second test and a gap

varying between 6 and 10 inches was present between the building and the ground thus allowingshock to get underneath the building during the second test.


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Figure 71. Test II - Roof Deck Damage

Figure 72. Test II - Floor Deck Damage

Sliding of the building was measured actively utilizing an accelerometer and passively by spraypainting around the building base plates. After the second test the building slid between thirteen

and twenty inches as shown in Figure 73.


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Figure 73. Test II - Passive Building Sliding Measurements

1

2

3

4

1

2

3

4


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52

The HVAC unit was heavily damaged by the second test as evidenced in Figure 74. The airreturn intake was blown into the work room at the end of the structure; the exterior unit was

heavily bent with the blower cover no longer attached to the unit. There was also evidence of

HVAC duct bulging inside the building, as shown in Figure 75. However, it is not clear whetherthe damage was caused by shock inside the duct or blast response of the roof.

Figure 74. Test II - Damage to HVAC: (a) Exterior and (b) Interior

Figure 75. Test II - Damage to HVAC Duct

Although there was no failure of the reflected wall the damage to the interior of the building was

heavy and a significant amount of interior debris was generated from the High Response of the

reflected wall. Figure 76 through Figure 80 detail the level, energy and hazardous nature of the

interior debris. In Figure 76 the damage to the end office is highlighted by the severedisplacement of the interior metal stud wall, throw of the gypsum wall sheathing and

fragmentation and throw of the book shelf and desk. The desk edging was thrown at a high force


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impacting the office hallway door and penetrating the door as shown in Figure 77. Furtherevidence of debris impacts on the back wall surfaces was also evident.

Figure 76. Test II - Office Room: (a) Pre-Test and (b) Post- Test

Figure 77. Test II - Desk Debris Impacts: (a) Door Scarring and (b) With Impacting

Debris


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The bathroom of the building was moved between 2 and 3 feet towards the back of the structureand into the hallway as shown in Figure 78. In Figure 79 debris from the reflected wall and

ceiling can be seen on the sink and cabinet located in the rear of the work room. Part of the

reflected wall desk top is also visible in Figure 79 having been thrown to the rear of the building.

Figure 78. Test II - Central Work Room: (a) Pre-Test and (b) Post Test

Figure 79. Test II - Interior Debris


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Overhead light fixtures were found to be mostly intact with just a few fixtures dangling but still

at the level of the drop ceiling as shown in Figure 80.

Figure 80. Test II - Light Fixture Damage

5.3.Structural Response MeasurementsAs discussed in Section 3.4.2, the building was instrumented to actively record structuralaccelerations of sliding and tipping, the reflected wall panel and end wall eave strut. The

acceleration data was filtered and integrated twice to produce displacement time histories. The

wall panel accelerometers recorded the kinematic sliding of the building as well as the flexuralresponse of the wall panel. Therefore, the sliding response had to be subtracted from the wall

panel response in order to obtain the wall panel relative displacement time history. A summary

of the active response measurements are provided below in Table 8. The wall panel response

exceeded the pretest prediction of 12.75 inches by 40%. The eave strut response was moderate,about 3 degrees of support rotation. The sliding response was recorded in building corner 4, see

Figure 26. The recorded sliding response, using the passive marking of the supporting concrete

pad, was 14 inches. A direct comparison to the active sliding accelerometer measurements couldnot be made due to the signal drift of the accelerometer data at the time scale necessary to

produce the peak sliding response.

Table 8. Test II - Measured Response Summary

Measured ResponseComponent

max (in) (deg)Wall Panel

17.5 in 16.2

Eave Strut 3.9 in 3.4Sliding

*-

Tipping* -

*Accelerometer data drifted therefore data was not reliable at time

necessary to integrate peak response for sliding or tipping. See

Section 5.2 Figure 73 for passive sliding measurements.


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5.3.1. Sliding and Tipping Response

The sliding and tipping measurements experienced some drift of the signal at later times

preventing the active measurement of sliding and tipping at time scales necessary for peak

kinematic building movement. However, the data was sufficient in the time scale of peak wallpanel response, about 20 msec. The acceleration and integrated sliding data is presented below

in Figure 55. Peak sliding accelerations were on the order of 25 gs. The active tippingacceleration measurements could not be evaluated due to loss of the signal as shown in Figure

56.

Time (msec)

Accele

ration(in/msec^2)andVelo

city(in/msec)

Displacement(in)

-5 0 5 10 15 20 25 30 35 40-0.3 -6

-0.25 -5

-0.2 -4

-0.15 -3

-0.1 -2

-0.05 -1

0 0

0.05 1

0.1 2

0.15 3

0.2 4

0.25 5


Figure 81. Test II - Measured Sliding Time History


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Time (msec)


Displacement(in)

-3 0 3 6 9 12 15 18-0.4 -4

-0.3 -3

-0.2 -2

-0.1 -1

0 0

0.1 1

0.2 2

0.3 3

0.4 4


Figure 82. Test II - Measured Tipping Time History

5.3.2. Wall Panel Response

The wall panel acceleration time history and integrated data is presented below in Figure 83.

The peak acceleration of the wall panel including sliding was recorded to be approximately

2,000 gs. The accelerometer recorded both the wall panel response and kinematic sliding.Therefore, in order to properly assess the panel displacement time history, the sliding response

must be subtracted. The relative wall panel displacement time history is presented in Figure 84.

The peak recorded wall displacement relative to the supporting structural members was 17.5inches. The wall panel response exceeded the pretest prediction due to eave strut deformation

that was more pronounced in the test. The structural model was revised to incorporate this

flexibility and better matched the test. This revised model was used to predict strains occurringin the wall panels during the tests and to revise the blast capacity calculation for strain and for

support rotation.


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Time (msec)


Displacement(in)

-5 0 5 10 15 20 25 30 35 40 45-2 -20

-1.5 -15

-1 -10

-0.5 -5

0 0

0.5 5

1 10

1.5 15

2 20

Raw Acceleration DataFiltered Acceleration DataVelocityDisplacement

Figure 83. Test II - Total Wall Panel Response Time History (Includes Sliding)

-40

-30

-20

-10

0

10

20

30

0 5 10 15 20 25 30 35

Time (msec)

Displacement(in)

Wall Panel Displacement

Figure 84. Test II - Relative Wall Panel Response Time History


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5.3.3. End Wall Eave Strut Response

The end wall eave strut measured response time history is presented below in Figure 85. The

peak eave strut acceleration was approximately 1,500 gs. The peak displacement as integrated

from the acceleration time history was 3.9 inches which corresponds to a support rotation of 3degrees.

Time (msec)

Acceleration(in/msec^2

)andVelocity(in/msec)

Displacement(in)

0 2 4 6 8 10 12 14 16 18 20-5.6 -5.6

-4.8 -4.8

-4 -4

-3.2 -3.2

-2.4 -2.4

-1.6 -1.6-0.8 -0.8

0 0

0.8 0.8

1.6 1.6

2.4 2.4

3.2 3.2

4 4Raw Acceleration DataFiltered Acceleration DataVelocityDisplacement

Figure 85. Test II - End Wall Eave Strut Response Time History


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6. Summary

ABS Consulting conducted two full scale field tests utilizing 1,250 pounds of ANFO explosiveon a standard 8 psi, 200 msec Heavy Response Hunter blast resistant modular building. The

purpose of the explosive testing was to determine performance of the building at the upper limit

of Medium Response (Test I) and the upper limit of High Response (Test II). Testing consistedof the detonation of a 1,250 lbANFO charge at a range of 100 feet for Test I and 75 feet for Test II.

The ANFO charge was placed on the door side of the building for Test I and the opposite wall

for Test II. Peak side-on pressures were 9.7 psi for Test I and 17.4 psi for Test II.

Test I - Medium Response

Performance of the structure in Test I was consistent with ASCE Medium Response. Whileprimary components exhibited some plastic deformation, structural integrity was not

compromised

Documents

Hunter Bldg Test 2008