iß

o

9 MNCSUANSOUS PAKR N-TM

AIRBLAST LOADING OF A LARGE METAL SHIPPING CONTAINER

Lmorakery Invtrtigation r\ p\ S"*

6. L Cwr», R. E. Walk« W sEP S 19T0

CLEARINGHOUSE tor Föderal Scientific & TecHnic.il Information Springfield Vi ^2151

July 1970

Spomemi by Offic«, Chief of EnginMrt, U. S. Army

tar U. S. Army EnginMr Watoiwayi ExpMimMk Stotion, Vidttburg, MntiMippi

inn OOCUimm ll«i PWn IIIIIIUWU nn ymmm vtt Mit; Hi dhWNthHi It imtaKtd

^

...

THIS DOCUMENT IS BEST QUALITY AVAILABLE. THE COPY

FURNISHED TO DTIC CONTAINED

A SIGNIFICANT NUMBER OF

PAGES WHICH DO NOT

REPRODUCE LEGIBLYo

Destroy thil report when no longer needed. Do not return it to the originator.

The finding* in thi« report are net to be construed at an official Department of the Army position unless so designated

by other authorised documents.

MISCELLANEOUS PAPER N-70u5

AIRBLAST LOADING OF A LARGE METAL SHIPPING CONTAINER

Laboratory Investigation

by

6. L Cam, R. E. Walkor

July 1970

Sponsored by Offica, Chief of Engineers, U. S. Army

Task 01

Conducted by U. S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi

AKMV-MIIC vicKaauao. Ml««.

This document hss been approved for pubNc reletse end ssle; Its distribution is unlimited

ABSTRACT

The objective of the test program reported herein was to determine if a large metal ship-

ping container would provide a sufficient degree of protection from simulated nuclear weapon

blast effects to make it suitable as a small protective shelter.

This report describes the tests of two Container Express (CONEX) containers that were

instrumented and subjected to blast loads in the Large Blast Load Generator (LBL(i) facility

at the U. S. Army Engineer Waterways F.xperiment Station (WES).

The containers were buried in dense, dry sand with 18 inches of sand over the roof and

subjected to blast load pressures of approximately 11, 15, and 34 psi. A total of 45 channels

of instrumentation were used to measure the following parameters; strain in the roof, side-

wall, and floor; vertical deflection of the roof; accelerations in the roof, sidewall, floor, and

free field; blast pressure at the soil surface and free field; and pressure inside the container.

For the first two tests, a container was placed base down in the LBLG and subjected to

pressures of 11 and 34 psi, respectively. The initial test caused only moderate damage to the

container; however, complete roof collapse resulted from the second test. For the final test,

an inverted (base up) container was subjected to a pressure of 15 psi. Damage to the con-

tainer was moderate.

Results of the test program indicate that the CONEX container could be utilized as a

small protective shelter. If the container were buried with the base up, it is believed that it

would withstand a pressure load of approximately 20 psi.

PREFACE

I lu- investigation reported herein was aeeomplished by personnel of the Nuclear Weapons

I fleets Division (NWKD), U. S. Army Engineer Waterways Experiment Station (WES), during

the period July through September 1967. The work was sponsored by the Office, Chief of

Engineers, Department of the Army, as a part of Task 01, "Engineering Studies and Inves-

tigations" in the "Military Engineering Applications of Nuclear Weapons Effects Research"

(MEANWhR) project.

The study was under the general supervision of Mr. G. L. Arbuthnot, Jr., Chief of

NWEI). and under the direct supervision of Mr. W. J. llathau. Chief, and Mr. J. V.

Dawsey. Jr., Project Manager, of the Protective Structures Branch. This report was prepared

by Messrs. G. L. Carre and R. E. Walker of the Protective Structures Branch.

Directors of the WES during the conduct of this study and the preparation of this re-

port were COL John R. Oswalt, Jr., CE, COL Levi A. Brown, CE, and COL Ernest D.

Peixutto, CE. Technical Directors were Mr. J. B. Tiffany and Mr. F. R. Brown.

CONTENTS

Page

ABSTRACT 3

PREFACE 4

CONVERSION FACTORS, BRITISH TO METRIC UNITS OF MEASUREMENT . 7

CHAPTER 1 INTRODUCTION 8

1.1 Background 8 1.2 Objective 8 1.3 Scope 8

CHAPTER 2 EXPERIMENTAL PROGRAM 10

2.1 Test Apparatus 10 2.2 CONEX Description 10 2.3 Instrumentation II

2.3.1 Pressure Measurements 11 2.3.2 acceleration Measurements II 2.3.3 Strain Measurements 11 2.3.4 Deflection Measurements 11 2.3.5 Soil Stress Measurements 11 2.3.6 Cata Recording Equipment 12

2.4 Test Geometry and Procedures 12

CHAPTER 3 TEST RESULTS 21

3.1 Visual Observation of Damage 21 3.2 Presentation of Data 21

3.2.1 Pressure Data 21 3.2.2 Acceleration Data 22 3.2.3 Strain Data 22 3.2.4 Deflection Da^ 22 3.2.5 Structure Material Properties 22

CHAPTER 4 DISCUSSION OF RESULTS 51

4.1 Structural Integrity 51 4.2 In-Structure E^nvironment 52

CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 54

REFERENCES 55

TABLE

3.1 Peak Displacements of CONEX Roof 23

FIGURES

2.1 Large Blast Load Generator (LBI.G) 13 2.2 Half-section of the Blast Load Generator 14 2.3 Large CONEX 15

2A COM-.\ location .mil position of free-field instrumentation in LBLG test chamber 16

2.5 Locations of CONEX instrumentation 17 2 f> Container instrumentation 18

Transducers useii in the test program 19 Container positioned in test chamber prior to final backfill placement . . 20 Damage to CONEX: lest 1 24 Damage to CONEX; Test 2 25 Damage to CONEXi Test 3 27 Typical surface pressure histories 28 Typical internal pressure hittoriet; tiage IP1 29 Free-field acceleration at floor level; Clage Al, Tests 1 through 3 . . . 30 I'ree-fielil acceleration at midstrueture depth; (läge A2, Tests 1 through 3 31 Acceleration at CONEX floor; Ciagc A4, Tests 1 through 3 32 Acceleration at CONEX roof; Ciage A5, Tests 1 through 3 33 Acceleration at CONEX sidewall, Ciage A6, Tests 1 through 3 34 Free-field velocity at floor level; Ciage Al, Tests 1 through 3 35 Free-field velocity at midstrueture depth, Ciage A2, Tests 1 through 3 36 Velocity at CONEX floor; Ciage A4, Tests 1 through 3 37 Velocity at ClONKX roof; Ciagc A5, Tests 1 through 3 38 Velocity at COMFX sidewall, Ciage A6, Tests 1 through 3 39 Free-field displacement at floor level; Ciage Al, Tests 1 through 3 . . . W Ireefield displacement at midstrueture depth; Gage A2, Tests 1 through 3 Displacement at CONEX floor; Ciage A4, Tests 1 through } 42 Displacement at CONEX roof; Ciage A5, Tests 1 through 3 "*3 Displacement at CONEX sidewall; Ciage A6, Tests I through 3 44 Ireefield acceleration, velocity, and displacement at roof level; Ciage A3. Test 2 45 Selected strain gage signatures; Test 1 46 Selected strain gage signatures; Test 2 47 Selected strain gage signatures; Test 3 48 Relative displacement-time history between CONEX floor and roof; Ciage CD1, lest 1 49 Stress-str.un curve for CONEX tensile specimen 50 Tolerance of eardrums to fast-rising overpressures (from Reference 4) . . 53

2.7 2 « 3.1 3.2 3 3 3.4 3.5 3.0 3.7

3.« 3" 3.10 3.11 3.12

3 13 3.14 3.15 3.10 3.17

3 18 3.1» 3 20 3.21

3.22 3 23 3.24 3.25

3.26 4.1

41

CONVERSION FACTORS, BRITISH TO METRIC UNITS OF MEASUREMENT

British units of measurement ustil in this report can be converted to metric units as follows.

Multiply By To Obtain

inches 2.54 centimeters

feet 0.3048 meters

cubic feet 0.0283168 cubic meters

pounds 0.45359237 kilograms

tons (2,000 pounds) 907.185 kilograms

pounds per square inch 0.070307 kilograms per square centimeter

kips per square inch 70.307 kilograms per square centimeter

pounds per cubic foot 16.0185 kilograms per cubic meter

inches per second 2.54 centimeters per second

feet per second 0.3048 meters per second

CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

The Container Express (COM X) i\ a laryc metal shipping container that can hold mate-

rials weighing up to 5 tons. The CONEX was designed to speed the movement of cargo and

in protect goods from loss, damage, ami pilferage. Thousands of the containers have been

slii[i[u-il to Southeast Asia (SI A). As very lew containers have been returned, it is evident

that countless additional uses have been found for the CONEX in the Theater of Operations.

lor example, the metal containers are being converted into dispensaries, offices, supply rooms,

command posts, and fighting fortifications.

Since the CONEX is being successfully used to wirhstand the effects of conventional

weapons, n was hypothesized that a standard container might be adequate to resist the airblast

luads from nuclear weapon detonations.

1.2 OBJECTIVE

The objective of this study was to determine the response of a buried CONFX subjected

to simulated nuclear weapon blast effects. The specific objective was to determine if the

CONEX, as manufactured, would provide a sufficient degree of protection to make it suitable

as ,i small protective shelter when subjected to airblast loading conditions characteristic of nu-

clear weapon detonations.

1.3 SCOPE

In accomplish the objective of this siudy. three tests were conducted in the Large Blast

load Cicnerator (I.BLCi) facility at the U. S Arms Engineer Waterways Experiment Station

(VVKS) i>n CONEX containers buried in sand to a depth of 18 inches. The first CONEX was

placed in the I.IUd base down and subjected to surface pressures of 11 and 34 psi. A sec-

ond CONhX was TIUII placed in the I.HI.C base up and subjected to a pressure of 15 psi.

1 he structures tur .ill tests were instrumented to record the following measurements (1) steel

A table ot (actors (or convfrtmq British units o( measurrment to metric units is presented on page 7.

strains. (2) top, base, and sidcwall accclcratiün, and (3) internal pressures. Additionally, free-

field aeceleration, and soil stress and surfaee pressure measurements were recorded.

J

CHAPTER 2

EXPERIMENTAL PROGRAM

2.1 TEST APPARATUS

I tu I.KI.d (csi ik".uv WJS ik-Mgncil pnnunly to list large model or prototype protective

striutures suhjivtcd to pressure» Mntulating those generited by both kiloton and megaton nu-

ilear devices I'he structures can l>c subjected to dynamic loads to 500 psi at a rise time of

appruximatcly 2 to 4 mttc and at durations ranging from milliseconds to several seconds.

The I.KI.d (ligurc 2.1) has two basic components, the central firing station (CIS) and

the test clumhcr The CI-'S is a massive, posttensioned, prestressed concrete reaction structure

dcM^ncil to resist the dvnamic loads generated in the test chamber. The two test chambers

are cxiindricji steel bins iproximately 23 feet in diameter that contain the test media and

test structures The test chamber (l-igure 2.2) is composed of three 3-1/3-foot-high C rings

that are stacked on a wheel-mounted platen One b ring containing a baffle grid and 15 fir-

ing tubes is seated »n the uppermost C ring. To complete the test chamber, one A ring

eijuipped with tjuick-opemng, blast-exhaust valves is seated on the B ring.

The assen.hled test chamber is rolled into the tunnel of the CFS, the platen is lowered

to rest on the base slab, and the A ring is elevated to bear against the ceiling of the CFS.

The test device is described in detail in References I and 2.

2.2 CONEX DESCRIPTION

The COM \ (Figure 2.3) is a large, metal, box-shaped, reusable shipping container Two

sizes, 135 and 295 ft', are available, however, only the larger size was considered for this test

program. The load-carrying capacity of the large container is 10,000 pounds. Its tare weight

is approximately 1,600 pounds. Access to the container is provided by two doors that close

to torm the container ront and are secured with a quick-opening door handle.

The container has internal dimensions of 8 feet 2 inches long, 6 feet wide, and 6 feet

hiy.n. Outside dimentions are 8 feet 6 inches long, 6 feet 3 inches wide, and 6 feet 10-1/2

inches high Inside and outside volumes of the container are 295 and 365 ft', respectively.

Hie lar^c container is fabricated from IK-iia^c-thick corrugated steel welded at all joints.

A double wall tlmkncss is provided at the container roof and floor. This double thickness is

Id

obtained by spot-welding an 18-gagc-thick plate to the top surface of the corrugated roof and

floor.

The container is mounted on 3/16-inch-thick steel skids, and forged-steel lifting lugs are

provided to facilitate handling and storage. A 1/4-inch-thick steel bar, 6 inches wide by

8 feet 2 inches long, is welded to the outside floor surface. This bar is centered between the

skids and serves as a floor stiffener.

2.3 INSTRUMENTATION

The test structure and free-field gage locations remained the same for all three tests and

arc shown in Figures 2.4 through 2.6. Some of the transducers used are shown in Figure 2.7.

2.3.1 Pressure Measurements. Strain-gage-type pressure transducers were used to deter-

mine free-field pressure, surface pressure, and pressure inside the structure. Eight gages were

positioned at the ground surface and two inside the structure. The sand surface gages were

nounted on wooden trusses buried flush within the sand (Figure 2.8).

2.3.2 Acceleration Measurements. Structure and free-field accelerations were measured at

locations shown in Figures 2.4 through 2.6 with strain-gage-type accelerometers. Free-field ac-

celerometers were cast in sand-plaster mixiures with densities approximating those of the sand.

2.3.3 Strain Measurements. Strains in the roof, floor, and one side of the CONEX

were measured at locations shown in Figure 2.5 using foil-type strain gages (gage length,

1/4 inch; gage resistance, 120 ohms; gage factor, 2.04). Twenty strains were measured by

10 gages positioned on the inside and 10 on the outside container surfaces. At roof, floor,

and sidewall inside and outside center spans, two single-element gages were placed at 90-degrce

angles to each other to indicate two-directional steel strain. To obtain a four-arm bridge cir-

cuit, the single active gages at each gage location on the structure were matched with three

similar gages mounted on steel blocks located outside the test chamber.

2.3.4 Deflection Measurements. Deflection of the CONEX roof was measured with a

linear potentiometer. A steel pipe was mounted to the container floor to support the gage.

The deflection gage was used only in the first test and had a capability of measuring deflec-

tions of 3-1/2 inches up or down. Figure 2.6 shows the deflection gage mounted on the

structure.

2.3.5 Soil Stress Measurements. Free-field soil stress measurements were made for all

11

tests. Soil stress was measured using diaphragm-pressure gages developed at WES (Refer-

ence 3). The soil pressure gages were placed at the structure roof, middle, and floor

elevations.

2.3.6 Data Recording Equipment. Data were recorded during the test with four high-

speed oscillographs operating at a chart speed of 160 in/sec for 5-second durations and four

magnetic-tape recorders operating at recording speeds of 60 in/sec.

2.4 TEST GEOMETRY AND PROCEDURES

For each test, the CONEX container was placed in the center of the LBLG test cham-

ber in order that side effects would be minimized and a balanced load distribution obtained.

The base of the container was approximately 2 feet from the test chamber bottom; therefore,

for practical purposes, it was assumed that the b.'se rested on a rigid foundation. After the

CON'F.X had been placed in the LBLG, all electronic instrumentation was connected and

electrically balanced.

A local sand, designated Cook's Bayou sand, used for backfilling in all tests is described

in detail in Reference 2. The sand was placed in the test chamber in 6-inch increments and

compacted with a plate vibrator to a density of about 102 pcf, at which the angle of inter-

nal friction was approximately 37 degrees. The sand was placed to an elevation 18 inches

above the containers for all tests. An automatic control system sequentially started the data

recording devices, ignited the charge, and opened the blast valves to exhaust the pressure.

For the first two tests, a CONEX was placed in the LBLG base lown, as shown in Fig-

ure 2.8a. The third test geometry was identical with that illustrated for the two previous

tests, but the container was inverted (Figure 2.8b).

12

c

c c

-5

I» J

LI c =

13

■g o

_2 S3

3

14

1500-933

Figure 2.3 Large CONEX.

15

L^

SECTION A-A

LEGEND

O SURFACE PRESSURE GAGE • SOIL PRESSURE GAGE * ACCELERATION GAGE

Figure 2 in I.Kit

.4 ('ONI X location and position of free-field instrumentation

test chamber.

1(>

^

LEGEND

STRAIN GAGES-ADDITIONAL GAGES WERE LOCATED ON THE OPPOSITE SURFACE TO THOSE ILLUSTRATED. THEY WERE NUMERICALLY IDENTI- FIED BY ADDING 10 TO THE ILLUS- TRATED GAGE POSITIONS. ACCELEROMETERS

INTERNAL PRESSURE GAGES

Figure 2.5 Locations of CONEX.

17

J

Figure 2.6 Container instrumentatiün.

18

r O o

—*

— N

E

IM 5.

c

s a

c 3 | C

■—o

19

a. »ct'ore tests 1 and 2 (base down).

b. Before test 3 (base up).

Figure 2.8 Container positioned in test chamber prior to final backfill placement.

20

CHAPTER 3

TEST RESULTS

3.1 VISUAL OBSERVATION OF DAMAGE

For the first test, the buried CONEX container was subjeeted to a surlaee pressure of

11 psi. After the shot, the container was uncovered and the damage observed. The container

roof had sustained a permanent deformation of 3.2 inches at the center. A crease had formed

at the rear edge (west) of the roof and extended approximately 3 feet toward the center.

Kuckling of three corrugations on the inside surface of the roof was observed. No welding

failures were noted, and overall damage to the structure was assessed as moderate. The nota-

ble damage sustained by the structure as a result of Test I can be observed in tigure 3.1.

A second test was conducted, and the structure was subjected to a surface pressure of

34 psi. A severe shear-type failure of the structure roof occurred (Figure 3.2a). In addition,

inward deformation of the sides, back, and front was noted (Figure 3.2b). After the CONEX

was uncovered, the roof, which had been blown to the floor, was removed. The damaged

roof is shown in Figure 3.2c. Note that the inside corrugated layer was flattened by the

blast. Damage to the structure bottom was minor (Figure 3.2d).

A third test was conducted on an inverted CONEX placed in the LBLCi. A pressure of

15 psi was measured at the surface. Damage to the structure was moderate. A level survey

conducted on the container showed a 2.2-inch permanent deflection at the roof center

(Figure 3.3).

3.2 PRESENTATION OF DATA

To facilitate data reduction, all recorded analog data were digitized at a sampling rate of

12 kc and processed on a central processor. Due to inconsistencies in the recorded stress-time

histories for the free-field stress gages (SS gages), the records for these gages have been elimi-

nated. However, selected pressure, displacement, acceleration, and strain results are presented.

3.2.1 Pressure Data. Typical surface pressure-time and internal pressure-time histories

for the three tests are presented in Figures 3.4 and 3.5, respectively. The mean pressures

shown in these figures were determined in the following manner: first, a straight line was

constructed through the impulse-time histories (plots not shown) for all pressure records of

21

each test, icconii, tin tlnpc (impulse divided by time) of this straight line was considered to

be the mean pressure tor each gage signature, finally, the mean pressures for each test were

arithmetically averaged

3.2.2 Acceleration Data. Structure and free-field accelerations along with the velocities

and displacements are presented in I igures 3.6 through 3.21. The velocities and displacements

were obtained by single and double integrations of the acceleration-time histories. A uniform

baseline shift with a magnitude equal to the average acceleration was applied to each accelera-

tion trace to adjust for baseline offsets.

3.2.3 Strain Data. Selected strain-time signatures for Tests 1 through 3 are shown in

ligures 3.22 through 3.24

i.2 *, Deflection Data. Relative displacement between the CONEX root' and floor for

lest 1 is shown in Figure 3.25. A summary of peak displacements at the center of the roof

as recorded for Tests I and 3 is presented in Table 3.1.

3.2.5 Structure Material Properties. Four tensile specimens were cut from different lo-

cations on the CUNKX and tested statically. A composite stress-strain curve is shown in

Figure 3.26.

22

TABLE 3.1 PEAK DISPLACEMENTS OF CONEX ROOF

Test No. Mean Pressure Peak Midpoint Displacement

Dynamic8 Permanent" Relativec

psi inches inches inthes

1 11 4.9 3.2 3.5

3 15 3.1 2.2 mm

a Double integration of accelerometer A5. D Prcshot and posttcst level survey. c Deflection gage CD1.

23

L_^ M^

a. Roof deflection and damage.

b Interior view of roof buckling.

Figure 3.1 Damage to CONKX; Test 1.

24

a. Posttest view prior to excavation.

b. Partially uncovered container (top is buried inside container).

Figure 3.2 Damage to CONF.X; Test 2 (Sheet 1 of 2).

25

c. CONEX top after removal (bottom layer was corrugated but was flattened by blast wave.

d. Minor damage to bottom.

Figure 3.2 (Sheet 2 of 2).

26

i h

K w z s

i E

id

27

20

10 ltifi*Y^*~'*s*T MEAN PRESSURC, 11 PS/

TEST 1, GAGE SP4

20 40 60 80 100 120

MEAN PRESSURE, J4 PS/ TEST 2. GAGE SP3

100 120

MEAN PRESSURE, ?5 PS/ TEST 3, GAGE SP2

120

Kigurc 3.4 Typical surface pressure histories.

28

TEST 1

100 ISO 200 250

TEST 2

250

TEST 3

MEAN PRESSURE. 0.92 PSI

I _L J_ J_ J 250 50 tOO 150

TIME,MSEC

200

Figure 3.5 Typical internal pressure histories: Gage MM.

2«

»r T6ST1

^^^i^m^^mmm^ß

i X 50 100 150

TIME, MSEC

200 250

20 i-

Z c

< 0

UJ

-20 50 100 150

TIME, MSEC

TEST 2

200 250

20 i-

-20

"H»«^* >kw««W«—

TEST 9

L^f\/'l ;^ /* V>Si^^',*^'»«W««»'l*l^^*«<^,l<M»<»^*>^l«W«»W*»<li«lW«*>l*<l|>>WI%»'»«ir<»'>i»<»l»»iM'

i. 50 100 150

TIME, MSEC

200 250

DOWNWARD I MOTION 1

l-igure Vft Ircc-fidd acceleration at floor level; Cage Al, Tests 1 through J.

30

TEST 1

250

to

li *

7 -io z o h 5 -20 ID J HI

y -30 <

-40

TEST 2

fyll'!^

50 100 150 200 250

10

M^ ^n», / \^,^V',l''"W^w*l>'*\i* ^>*«r"»>"»«'l|ltW W '«S»1', nVw*»"^»»'«!*»«»

•10

-20 -

-30

^

TEST 3

50 100 ISO

TIME, MSEC

200 250

DOWNWAR MOTION

D I ligurc 3.7 Free-field acceleration at midstructurc depth; Ciagc A2, Tests 1 through 3.

31

-5 100

TEST 1

/yy%^wv'Vyw**

150 200 250

50

TEST 2

a. hi J 111 u u <

/«PACT OF ROOF

M^V*- <k^qjiAft*m&mtk MM ̂ M^i+jiWMl?*** ■ (IW<iV/IW— m -50

50 100 150 200

50 r

±

TEST 3

100 150

TIME, MSEC

200 250

DOWNWARD MOTION

Kigurc .VH Acceleration at CONEX floor; Gage A4, Tests l through 3.

32

-50 100

TtST 1

tffv^ppM*«i, „, m „,„„ , 1|p,r

150 200 250

500r-

t- <

U

-500

200

-200 50 '00 150

TIME, MSEC

TEST 2

250

200 250

DOWNWARD MOTION

Figure 3.9 Acceleration at CONEX roof; (Jage A5, Tests 1 through 3.

33

TEST 1

250

100

z o

< a u -i w u u <

^M^WWWP"^«"» «Wi»»*«^)!

TEST 2

MMi*^

■100 50 too 150 200 250

TEST 3

100 150

TIME, MSEC

250

INWARD MOTION

h'igurc 3.10 Acceleration at CONEX sidcwalt; Ciagc A6, Tests 1 through 3.

M

u Li

I- b.

>" t J 111 >

-0.10

-2

TEST 1

100 150 200 250

TEST 2

50 100 ISO 200 250

1 i-

100 150

TIME,MSEC

TEST 3

250

DOWNWARD MOTION

Figure 3.11 Frcc-ficld velocity at floor level. Gage Al, Tests 1 through 3.

35

o.2 r TEST 1

250

0.25 r

-0.25

TIME,MSEC

TEST 3

DOWNWARD i MOTION '

12 Frec.field velocity at midstructure depth;

('^CA2." Tests 1 through 3

}6

0.2 r-

-0.2 100

TEST 1

VW.

160 200 250

in

t- IL

>-" h

TEST 2

IMPACT OF FLOOR

^/

\i\r

J UJ >

-s 50 100 150 200 250

0.5,-

TEST 3

-0.5

100 150

TIME. MSEC

200 250

DOWNWARD MOTION

Figure 3.13 Velocity at CONEX floor; Gage A4, Tests 1 through 3.

37

lOr TEST 1

4^-

150 200 250

50 r

u ID

h U.

> t-

TEST 2

250

J tu >

100 150

TIME, MSEC

TEST 3

200 250

DOWNWARD MOTION

Figure 3.14 Velocity at CONEX roof; Gage A5, Tests 1 through 3.

3K

ü u V)

I- ü. >■"

I-

J U >

TEST t

280

ISO 200 280

1.8f-

0.8 -

100 180

TIME, MSEC

TEST 3

200 280

INWARD MOTION

Figure 3.15 Velocity at CONEX sidewall; Ciage A6, Tests 1 through 3.

39

0.0J4 i-

-0.024

TEST 1

250

u i u z

h z HI 2 UJ u < J a

a

-0.60

-1.20 50 100 150 200 250

-0.12 -

TEST 3

-0.24 50 100 150

TIME, MSEC

200 250

DOWNWARD MOTION

ligun- 3.16 Free-field displacement at floor level; Gage Al, Tests I through 3.

40

-0.6

-0.12

-0.18 50 100 ISO 200

J 250

ill z u z

K-" z 111 2 U O < J a. w a

o f-

-0.60

-0.12

-0.24 100 150

TIME,MSEC

200 250

DOVNWARD MOTION

Figure 3.17 Free-field displacement at midstructure depth; Clage A2, Tests 1 through 3.

41

TEST 1 0.\2 r-

-0.06 50 100 150 200 250

TEST 2

100 150

TIME, MSEC

250

250

DOWNWARD MOTION i

l-igurv y\H Displacement at COSTX floor; Gage A4, U'sts 1 through 3.

4:

4.8 ■-

2.4 h

100 200 250

TEST 2

250

50 100 150

TIME, MSEC

3.6 TEST 3

2.4 /

1.2

n -S 1 I 1 1 1 200 250

DOWNWARD MOTION

Figure 3.19 Displacement at CONFX roof; Gage A5, Tests 1 through 3.

43

0.36 t-

0.2*\-

0.t2

50 100 150

TEST 1

200 250

TEST 2

250

0,60 r-

-0.60 50 100 150

TIME, MSEC

TEST 3

200 250

INWARD 1

MOTION *

l'igurc yio displacement at CONEX sidcwall; (iagc A6, fests 1 through }.

44

tso

V 100 h z o

K SO u J u 8 o < 14-** NV^Y*

I «I »I« I III

-50 50 100 ISO 200 280

100 ISO 200 2S0

2.4 >-

50 100 ISO

TIME, MSEC

200 2S0

DOWNWARD MOTION

Figure 3.21 Free-field acceleration, velocity, and displacement at roof level; (läge A3, Test 2.

45

I

E3

mm* mm VI 100 ISO .TO ?so

1 000 - Eli 1 wo

1 A- +*~* -*-« mmm 0

-500 0 v^ I ■ l

so 100 ISO 200 no

a. ROOF

E6

so loo iso :oo 250

b. SIPEWALL

^

j—j—h

100 ISO 200 —I -500

250 0

TIME, MSEC

c. FLOOR

Kigurc 3.22 Selected strain gajic signatures; Test 1.

E20

SO 100 ISO 300 250

ARROW DIRECTION INDICATES COMPRESSION

46

-?0,000

E2

\

-4,000

1,000 r-

J 1 1 1 1 .5,000

£.12

ipl1 n^^

\^ -•'-—•■vf,.

-J I L. 50 100 150 ?O0 250

a. ROOF

50 100 150 »0 250

E6 750 EI6 '

/

Efi

/

1 1

>>1

1 1

t- —

1 0 50 100 150 200 25

EI9

/• •fW

_i i_ 0 0

TIME, MSEC

c. FLOOR

50 100 150 200 250

*RR0* DIRECTION INDICATES COMPRESSION

ligurc 3.23 Selected strain gage signatures; Test 2.

47

■■■

2.00Or

0

L3 2.0OOp

0 ■*

-1 1 1 1 1 -5.000 SO 10« ISO 200 2S0

EI2 |

^S" T'lfur fTTir"

I ' I _I I u

SO 100 ISO 200 250

a ROOf

SOOr

- v«*"

ES 500

yVV^^^^^VVV^A«^

kmmvßm

' ' 50 I0O ISO 200 250

EI5

j _i i i SO 100 ISO 200 250

750

SOC

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b. SI DE WALL

750

500

mmm**mmmmm*mm ^

MMMMM

-500 _1 L. 50 100 150 200

-500 250 0

TIME, MSEC

c. FLOOR

:i0 I

mmmmm

_l I u 50 100 ISO 200 250

ARROW DIRECTION INDICATES COMPRESSION

Figure 3.24 Selected strain gage signatures; Test 3.

4S

50 100 ISO

TIME, MSEC

200 250

Figure 3.25 Relative displacement-time history between CONEX floor and roof; Gage GDI, Test 1.

49

50 r-

40 f- ay =33 KSI

f = 1,300 nlN IN

JL X tO,000 20.000 30.000

STRAIN. filN/IN

a.. - 42 KSI

X 40.000 50.000

l-'igure 3.26 Stress-strain curve for CONEX tensile specimen.

50

CHAPTER 4

DISCUSSION OF RESULTS

4.1 STRUCTURAL INTEGRITY

Analysis of the strain data for Tests 1 and 3 as presented in Chapter 3 indicates that

yielding occurred only at the structure roof. It was noted that yielding occurred on both the

plate and corrugated roof sections in lest 1, whereas only the corrugated roof section yielded

in Test 3. For both tests, the strains recorded on the floor and sidewal! were considerably

less than the ultimate yield strain. Since Test 2 was a repeat shot on the Test 1 structure,

which had incurred permanent deformation, the results were not considered representative of

rhe ultimate load-carrying capacity of the CONEX. However, it is believed that the Test 2 re-

sults are representative of the most probable failure mode of the CONKX; consequently, the

test data were included in this report but were not considered in the final analysis.

A stiffness relation was developed to compare roof displacements resulting from Tests 1

and 3. The stiffness relation is defined as:

P.

' max

where

Kj = stiffness for the i'" test

Pm =• mean pressure, psi

max t maximum dynamic peak midpoint displacement of the roof for dynamic Kj , < inches (permanent midpoint displacement of the roof for static Kj , inches

Using the permanent displacement mean pressures shown in Table 3.1, the static stiff-

ness can be determined as;

L- 11 Psi > < Ki = i-r— ,— = 3.5 nsi/m 1 3.2 inches '

-.- *~,— = 6.9 psi/in 2.2 inches

Then the ratio

= 2.0

51

Hence, the inverted flour configuration (Test 3) yields a system that is twice as stiff as

tin; ordinarih placed container (Test 1).

In order to determine the dynamic stiffness, the dynamic displacements shown in

I able 3.1 can l>c used in lieu of the permanent displacements. Hence,

K| =2.2 psi/in

K3 = 4.7 psi/in

yielding a ratio of

K3 — = 2.1

Kl

As in the static case, the inverted floor configuration is the stiffer of the two systems.

The stiffness calculations are based on the assumption that the floor displacements (Fig-

ure > 18) are insignificant as compared with the roof midpoint displacements shown in

Table 3.1.

4.2 IN STRUCTURE ENVIRONMENT

In evaluating underground structures that are to be occupied by personnel, consideration

must be given to the shock and acoustic environment.

figure 4.1 was extracted from a paper (Reference 4) on the effects of overpressures on

the human car. Recorded peak internal picssure from Test 1 was less than 2 psi; consequently,

the probability of ruptured eardrums of occupants appears to be approximately 0.1 percent.

The peak infernal pressure from Test 3 was considerably less than that measured in Test 1.

According to the information published in Reference 5 on the tolerance of humans to

impacts, the magnitudes and durations of accelerations measured on the structure floor for

Tests 1 and 3 are significantly below injury levels.

52

d O IT < UJ

Q lü

D

Q.

CC

ü. o H Z UJ u IT UJ a

»9.3

99.0 - i 1 ' 1 ' ' ' M 1 i i 11111

98.0 - / / - 95.0 - / /

90.0 - *y /

-

80.0 - -

70.0 - -

60.0 - -

50.0 - -

40.0 - -

30.0 - -

20.0 - -

10.0 - -

5.0 - -

2.0

1.0

0.6 :

PEAK // INTERNAL / PRESSURE /

v-IX^/JJi /-^-EXTRAPOLATED

-

0.2

0.1

— < / 1 . 1 1 . . .1 j ■ i Mill

5 10 20

PEAK PRESSURE, PSI

50 100

Rigurc 4.1 Tolerance of eardrums to fast-rising overpressures (from Reference 4).

5 3

CHAPTER 5

CONCLUSIONS AND RECOMMENDATIONS

li.iw.l .MI the results nf ilns investigation, the following conclusions and recommendations

«ere reached

1 It the (»)\r\ is iitili/eii .is .1 small protective shelter, a definite structural advantage

can l>e achieved l>\ placing the structure upside down. This emplacement configuration would

In- ilesir.iMe .i^.imst conventional or nuclear weapon threats.

.' I IT peak pressures up to at least 15 psi resulting from the detonation of a nuclear

device, occupants <>t the CONK.X would not experience adverse shock or acoustical

environments

i Itased on the observed strains (rum this test series, it is believed that an inverted

(OSIX would withstand overpressures in excess of 15 psi; however, additional testing would

l>e iRvess.m in establish the ultimate load-carrying capacity of the shelter.

4 Ihese tests have shown that the CONEX is potentially an effective shelter against the

blast etteets ,it a nuclear device. Phereforc, it is recommended that in future programs, con-

sideration be given to hunk arrangements, entrances, exits, ventilation, emplacement techniques,

and other pertinent design and environmental criteria.

54

REFERENCES

1. Ci. E. Albritton; "Description, Proof Test, and Evaluation of Blast Load Generator

Facility"; Technical Report No. 1-707, December 1965, U. S. Army Engineer Waterways Ex-

periment Station, CK, Vicksburg, Miss.; Unclassified.

2. T. E. Kennedy, (i. E, Albritton, anil R. K. Walker, "Initial Evaluation of the Free-

Field Response of the Large Blast Load Generator"; Technical Report No 1-723, June 1966;

U. S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss.; Unclassified.

3. J. K. Ingram; "Development of a Free-Field Soil Stress Ciage for Static and Dynamic

Measurements"; Technical Report No. 1-814, Lebruary 1968; U. S. Army Engineer Waterways

Experiment Station, CE, Vicksburg, Miss.; Unclassified.

4. F. G. Hirsch; "Effects of Overpressure on the Ear-A Review"; Annals, New York

Academy of Sciences, October 1968, Vol 152, Art 1, Pages 147-162; Unclassified.

5. A. E. Hirsch; "The Tolerance of Man to Impact"; Annals, New York Academy of

Sciences, October 1968, Vol 152, Art 1, Pages 168-171; Unclassified.

55

Ur.djssifieü Jwtumj >.'l«>nltt «tton

DOCUMENT CONTROL DATA ■ R * 0 • ii.:: ml "'(« ■■it uf »hiirmt i mnJ utJmnmg tnrtotmi$on mwat W ft' .fä mltmn lh9 o»9*mll tipott Im e lm»»lll»ä)

"nr 1 ' * Citrputmf mulhu*!

U S Army Enijineer W.iit'rwav. i'xpermient Station Vicksburg Missisuppi

Unclassified |J» QmOKl*

AIRBLAST l,i.)AI)INC OF A LARGE METAL SHIPPING CONTAINER, laboratory Investigation

Fmdl report tifinm—. mIMI* Inltiml. f««l nmmmi

t,>arv 1. v'arrt- K 'bert K Walker

July 1^70 TOTAL MO OP PAttlt

63 i .>MTN«CT m

ft. »«O -IC T NO

«. I ask 01

Miscellaneous Paper N 70-5

31SI (Anr otf)*r ntmton *mt mmr ft* ftftftl#iW

tO OIITNIftw TlON tr * TIMCM T

This document has beer, approved for public release and sale, its distribution is unlimited.

li IPOMftOMtN« MILITAIIV ACTIVITY

Office, Chief of Engineers U S Army Washington. D C.

The obiective of the test program reported herein was to determine if a large metal shipping con tamer would provide a sufficient degree of protection from simulated nuclear weapon blast effectt: to make it suitable is a small protective shelter This report describes the tests of two Container Ex- press (CONF.X) containers that were instrumented and subjected to blast loads in the Large Blast Load Generator U.BLG) facility it the U S Army Engineer Waterways Experiment Station. Th.' containers were buned in dense, dry sand with 18 inches of sand over the roof and subjected to blast l.\i..i , ressun's of approximately II, 15, and 34 psi A total of 45 channels of instrumenta- tion were used to measure the following parameters strain in the roof, sidewall, and floor, vertical deflecti 'ti if the roof, accelerations in the roof, sidewall, floor, and free field, blast pressure at the soil surface and tree field, and pressure inside the container For the first two tests, a container was placed Sa.se down in the LBLG and subjected to pressures of II and 34 psi, respectively. Th» initial tost uned ir.lv moderate damage to the container, however, complete roof collapse resulted fcom the ;•>. : i test K r the final test, an inverted (base up) container was subjected to a pressure of 15 psi.

I in i ;•■ • the Lontainer .v.is moderate Results of the test program indicate that the CONEX con- ■.tr.-.v. ilt be utilized is a small protective shelter 'f the container were buried with the base up, it is believed that it w mid withstand a pressure load of approximately 20 psi.

DD.'rr..l473 ::-.c"?s,^; Unclassified icmrtty BBSSRSSBS

hü

J

UnclaMJfied ■»cyrltT CUnlflcaHoii

mot,* »T NOLI WT

Airblast waves

Blast effects

Containers

Protective structures

Shelters

Shipping containers

Unclassified l«curl!T ClaMincatton

60