NATIONAL BUREAU OF STANDARDS REPORT

2295

TEST OF PRECAST PRESTRESSED

ROOF PANEL NO. 1

(TYPE A)

by

C* T e Valenti* Jr s * T* W e Reichard

L. Ft Skoda and D, Watstein

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing of

the divisions and sections engaged in technical work. In general, each section is engaged in specialized research, development, and engineering in the field indicated by its title. A brief description

of the activities, and of the resultant reports and publications, appears on the inside of the back

cover of this report.

Electricity. Resistance Measurements. Inductance and Capacitance. Electrical Instruments. Magnetic Measurements. Applied Electricity. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Gage.

Heat and Power. Temperature Measurements. Thermodynamics. Cryogenics. Engines and

Lubrication. Engine Fuels. Cryogenic Engineering.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State

Physics. Electron Physics. Atomic Physics. Neutron Measurements. Infrared Spectroscopy.

Nuclear Physics. Radioactivity. X-Rays. Betatron. Nucleonic Instrumentation. Radiological Equipment. Atomic Energy Commission Instruments Branch.

Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chemistry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Aerodynamics. Engineering Mechanics. Hydraulics. Mass. Capacity, Density, and Fluid Meters. Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure. Chemistry of Mineral Products.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Machine

Development.

Electronics. Engineering Electronics. Electron Tubes. Electronic Computers. Electronic

Instrumentation.

Radio Propagation. Upper Atmosphere Research. Ionospheric Research. Regular Propagation Services. Frequency Utilization Research. Tropospheric Propagation Research. High

Frequency Standards. Microwave Standards.

Ordnance Development. These three divisions are engaged in a broad program of research

Electromechanical Ordnance, and development in advanced ordnance. Activities include

Ordnance Electronics. basic and applied research, engineering, pilot production, field testing, and evaluation of a wide variety of ordnance materiel. Special skills and facilities of other

NBS divisions also contribute to this program. The activity is sponsored by the Department of

Defense.

Missile Development. Missile research and development: engineering, dynamics, intelligence,

instrumentation, evaluation. Combustion in jet engines. These activities are sponsored by the

Department of Defense. • Office of Basic Instrumentation • Office of Weights and Measures.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT mS REPORT

1001-10-4704. February 17, 1943 2294

TEST OF PRECAST PRESTRESSED

ROOF PANEL NO . 1

(TYPE A)

by

C« T. Valenti, Jr D > T„ W. Reichard

L, F. Skoda and D. Watstein

The publication, repr

unless permission Iso 25.D.C. Such perm

cal ly prepared If tha

Approved for public release by the

pa,t ' ls prohlbl,ed

Director of the National Institute of

ld,ird3 ' Wa3hlngt0 "

>rt has been speclft- Standards and Technology (NIST) #rt for lt8 own U8e , on October 9, 2015.

CONTENTS

Page

Introduction 1

Description of Test Specimen 1

Fabrication of Specimen and Description of Materials

3.1 Forms

3.2 Prestressing Units

3.3 Welded Wire Fabric

3.4 Concrete

3.5 Pre s tres sing Technique

Testing Procedure

I4..I Test Setup

4-. 2 Method of Loading

4.3 Instrumentation

4.4 Description of Test

cm

r\j

oj

_d-_zfLT\'

lJ ’\

vD

TEST OF PRECAST PRESTRESSED

ROOF PANEL NO. 1

(TYPE A)

1. INTRODUCTION

The study of precast-pres tressed concrete roof panels

was initiated in the National Bureau of Standards at the request of the Bureau of Yards and Docks for the purpose of

establishing design data for prestressed thin shell ribbed

panels of various cross-sections.

The following report presents the data obtained in the

test of one prestressed roof panel, type A, slab 1.

2. DESCRIPTION OF TEST SPECIMEN

The prestressed roof panel tested was constructed in

accordance with Bureau of Yards and Docks plans (Sketch A-l,

October 4, 195>2) and specifications. The 5 ft by 2l| ft

panel was essentially a thin slab stiffened by two edge

beams and two transverse ribs. The longitudinal edge- beams

were 8-in. deep and 2 l/2-in. wide at the base. The outer

surfaces of the edge beam were plumb; the Inner surfaces

tapered up at a slope of 1.5 in. in 8 in. and became.an integral part of the slab. At a distance of 9 In. in from either

end, there were two transverse ribs. The transverse ribs

were 7 7/8-in. deep, 2-in. wide at the base, and tapered up

at a slope of 1 in. in 7 7/8 in. until they merged into the

slab. The portion of the slab enclosed by the longitudinal

beams and transverse ribs was 1-in. deep. At the two extremities if the panel, the slab was 3”in. deep.

The slab and the stiffening members were reinforced with

2-in. by 2-in. by 12 ga welded wire fabric. Each transverse

rib also Included two No. 3 deformed reinforcing bars, one at

the top and one at the bottom. These bars met the requirement

of A.S.T.M. Specifications A305-50T and A15-50T for deformed

reinforcing bars of intermediate grade. Each longitudinal

edge beam enclosed one ten wire Freyssinet prestressing unit

complete with flexible conduit and placed in a parabolic

curve. An overall view of the test slab is shown in figure 7*
- 2 -

3o FABRICATION OF SPECIMEN AND DESCRIPTION OF MATERIALS

3.1 Forms

Since the reinforcement was to be post-tensioned and

the specimen had to be supported along its entire length

prior to prestressing, the forms were constructed so as to

permit stripping of the web and side surfaces of the longitudinal and transverse edge beams while continuing to

support the base of the longitudinal edge beams. Therefore,

the form was elevated on wooden trestles to permit working

beneath the specimen without moving it. Figure 1 shows the

overall view of the form. The trestles were joined by

2-in. by i|-in. pieces of Douglas fir and leveled with an

engineer's level. The 2-in. by 4“in* struts were then

grouted with Hydrocal to assure complete bearing and eliminate deflections of the form under the weight of the concrete. Plywood was used for all cast surfaces of the

specimen to assure smooth surfaces. The web of the specimen

was supported with wedge shaped 2-in. by 6-in. pieces of

Douglas fir spaced lip in. on center. The wedges were cut so

as to permit complete support of the web and inner surfaces

of the edge beams. The outer surfaces of the edge beams

were supported lip in. on center as shown in figure 1.

3.2 Prestressing Units

Ten wire Freyssinet prestressing units were used to

apply the required prestress in the specimen. Tbeunits

were obtained from the Intercontinental Equipment Company,

Inc. of New York* N. Y. Each unit is complete with two end

anchorage cylinders, two end anchorage cones, one flexible

steel conduit, and ten 0.196 in. dia high yield point steel

wires. To determine the properties of the wire, two samples

were tested in tension in a 60,000 lb testing machine.

Strain data were obtained using both Tuckerman optical gages

and SR-lp bonded wire strain gages. Figure 27 shows the stress

strain curve and Table 1 gives the properties of the wire,

from data obtained with the Tuckerman gages. Two Freyssinet

double acting hydraulic jacks and one five gallon capacity

hydraulic pump were obtained from the above mentioned manufacturer to apply the pretensioning force to the specimen.

Details of the end anchorage units and the hydraulic jacks

in place for prestressing are shown in figure 6.
3.3 Welded Wire Fabric

Two in. by 2-in. by 12 ga welded wire fabric, obtained

from the American Steel and Wire Company, Washington, D. C.

was used to reinforce the web and edge beams of the specimen. The wire fabric was supported by l/2-in. slab bolsters.

The placement of the reinforcement in the form may be seen

in Figure 2. Segments of the wire fabric were measured with

micrometer calipers and the average diameter was found to be

0.10^1 in. Tensile tests were made on several sections of

the wire fabric, using Tuckerman optical gages to measure

strain. It was found that the properties of the wire varied

greatly among the individual specimens; the data obtained

from only one specimen, however, are given in Table 1 and

Figure 28.

3.1|. Concrete

Proportions of the concrete mix used were 1:2.48:2.02,

by weight. The cement factor was seven bags per cu yd.

White Marsh, Md . sand and pea gravel were used as fine and

coarse aggregates. The pea gravel was passed through a 3/8-in. standard sieve to obtain 3/ 8 -in. top size aggregate.

High-early strength Portland cement was used with calcium

chloride (2 percent by weight of cement) to permit early

stripping and prestressing. Figure 3 shows the slump test

made on the preliminary batch of the mix. The five 5 cu ft

batches used to fill the form had slumps varying from 1 l/2 in,

to 4 l/2 in. The specimen was cured under wet burlap for

four days, then air dried for three days to permit attachment

of SR-4 bonded wire strain gages. Ten standard 6-in. by 12-in.

cylinders were cast at the time the specimen was made. The

cylinders were cured in a curing chamber until they were tested.

The average compressive strength of four cylinders tested at

the time of prestress was 6760 psi. The remaining six cylinders, which were tested at the time the specimen was tested,

had an average compressive strength of 695>0 psi. Properties

of the concrete are given in Table 1 and the stress-strain

curve is shown in figure 26, It is noted here that the information in the Table, and the stress-strain curve, are

from data obtained from two specimens tested at the time of

prestress

,

3«5 Prestressing Technique

When the specimen was 20 days old, the first attempt at

prestressing was made. The two 10 wire bundles were slipped
- 4 -

into their respective flexible conduits which were cast in

each edge beam of the specimen,, The ends opposite the jacking point were anchored with the manufacturer’s end anchorage device. Since it was felt that the pressure gage

supplied by the manufacturer would not be sufficiently

accurate to measure prestressing forces transmitted to the

specimen* dynamometers were inserted between the end anchorage cylinders and the specimen at the jacking point. These

dynamometers were used to control the load applied to the

specimen. A close up view of the dynamometers and the hydraulic jacks in place for pre stressing is shown in figure

6. The first attempt at prestressing was not successful

since the load in the two edge beams varied. The variation

in the load applied may have been due to frictional losses

in the individual jacks. The prestress was released and a second attempt was made the next day. On the second attempt,

the load was applied uniformly to the edge beams by manipulating the proper control valve on the pump. The prestress

was applied in several increments and indications of micrometer dial gages, SR-lp strain gages on concrete and individual

Preyssi.net prestressing wires, dynamometers and pressure

gages were recorded. Figure 13 shows the changes in total

tension in the units after the jacks were removed. It can

be seen that 20,050 lb had to be applied to the jacks to obtain a tension in each unit of l8,2f?0 lb. A few minutes

later, at the time that final readings were taken’on all

gages, the tension in each unit dropped to 18,100 lb.

Distribution of deflections under prestressing at

various places in the slab are shown In figures lip * l£

,

and

16. Figures 22, 23, 24, and 25 show longitudinal strain in

the concrete and Table 4 gives transverse strains in the concrete under pre stressing

.

4. TESTING PROCEDURE

4.1 Test Setups

One day after the prestress was applied, the specimen

was moved to the testing piers by means of a lifting jig

and a three ton bridge crane. Figure 7 shows the overall

view of the lifting jig and the testing piers. The specimen

was supported at four points by 2- by 2 l/2- by 3/4“in» bearing plates and 2 l/2- by 3/4“in - dia rollers. The span

length between the rollers was 22 ft 4 in® The rollers and

bearing plates are shown in figure 7® One end of the specimen was set in place by lowering the bridge crane. The other

end was then supported by a 5 ton hydraulic jack and lowered

gently to its proper position. Hydrocal was used, between all

bearing surfaces to assure complete bearing of the specimen.
- 5 -

Lj.,2 Method of Loading

Water was used to apply the uniform load to the specimen

during test. Since large deflections were anticipated, it was

felt that the use of a single tank would cause too uneven a distribution of the water at large deflections. Therefore,

four individual 5- by 6- by 2 ft tanks were used to minimize

the concentration of load near the center of the slab. The

tanks were made of No. 8 treated duck and were coated with a fatty acid pitch material to make them watertight. Each tank

was loaded at the same rate and the total quantity of water

entering the tanks was measured with individual water meters.

The water meters are shown in figure 7« Figure 8 shows the

overall view of the test setup with the water tanks in place.

4»3 Instrumental ion

Deflections of the slab under load were measured with

0.001 in. micrometer dial gages and taut-wire mirror-scale

devices. The dial gages were located on the underside of

the slab at the same point at which measurements were made

during prestressing at the top of the slab. Five dial gages

were placed across the center cross-section of the spans and

three were placed at approximately the quarter point sections

of the span. A closeup view of some dial gages and some Sr=4

gages are shown in figure Ip- Dial gages were also placed

over the supports to measure any settlement of the supports.

Distribution of deflections as measured by the micrometer

dial gages are shown in figures- lip , 15, and 16. Figure 17

shows the load vs. deflection curves of the edge beams at

the center and quarter point sections. Distributions of deflections of the edge beams, as measured by the taut-wire

mirror-scale devices are shown in figure lo,

SR -Ip bonded wire strain gages were placed both transversely and longitudinally on thespecimen on top and bottom

of the slab, A total of 54 gages were used to measure strain

in concrete. The gages were placed across the center and

quarter-point sections of the specimen. Figures 19 and 20

show the distribution of longitudinal and transverse strain in

the specimen under the applied load. Figures 21, 22, 23, and

24 show the applied load vs. longitudinal strain at various

points in the concrete and table 4 gives the transverse strain

in the concrete through the pre tens ioning and loading cycles.
- 6 -

In addition, SR^-ip bonded wire strain gages were attached

to each prestressing wire at the end opposite the jacks so

that the distribution of stresses in a given unit might be

determined. Some of the gages were damaged before the test began because of the close working space in the conduit. Tables

3 and Ip show the comparison of stresses in each wire where

gages were not damaged.

It is noted that the tensile stresses observed in the

individual wires were in most cases higher than the average

stress indicated by the dynamometers. Arrangement of the

Sr-Ip strain gages on the individual wires of the prestressing

units is shown in figure Figure 12 shows the manner in

which the lead wires were brought through the end anchorage

cones

.

, ip. ip Description of Test

The specimen was loaded in increments of 10 Ib/sq ft and

readings were taken on all gages. The first noted cracks

occurred in both edge beams between ipO and lb/sq ft.

Figure 9 shows the first cracks in the «east edge beam. The

specimen was loaded to 60 lb/sq ft and that load was maintained

for 1 l/2 hr at which time additional readings were taken on

the gages. The load was continued to. 70 lb/sq ft but the micrometer dial gages had to be removed due to excessive deflections of the slab. The load was then removed from the specimen

by means of siphons to note the recovery. The transverse centerline of the slab recovered to within l/lp in. of its original

position and the tensile cracks closed up. Figure 10 shows the

same cracks as figure 9 with the load removed. The empty tanks

were removed from the specimen and the positions of cracks on

the top surface and on the under-side of the web were noted.

Figure 2^ is a sketch of all cracks that were observed on the

specimen after the load was removed. The next day, the specimen was reloaded to 60 lb/sq ft and additional measurements

were taken until failure occurred at 80 lb/sq ft. It should

be noted here that at this load the Freyssinet wires in the

west edge beam began slipping through the end anchorage devices

and the tensioning force in it was lost completely. The slab

rotated and the east edge beam twisted. Figure 12 shows details of the rotation at the north end of the slab. It can be

seen that the No. 3 reinforcing bar was all that kept the east

edge beam from pulling away from the transverse rib.
r-fi

to

in

in

Eh

to

P. §

F?>19

to

O CO

2: Eh

to

to

PH

VOoK P ci> ng»-h w {* E-« to S Eh

Eh t-H

CtJ S O t-H Ph P o

s*

Ph

fc> t-H P

to

a.

*-» to

P-4

to

pH«

5ES t-t 0 Q 0 0 O vo 0 O 1

<* • •k 0 CO VO

CO VO

cm o vo o o ft 8?

VOH

CO vo o8COI—I

CVI III o§m> pm oo? 8 CU VO

pH

vo

vo CVI r—

CO 0 CM 8a O9 &

<M VOCTv

1—I

VO < >3 c5 t—tI to CM CVI Cri pH 3 pH W t-H P

>» *5>» P t-H t23 O

Sd

t-H viS t-H CO | to P W

CM 9

>» Eh

p S O CO a 0 H <2 p 1 « EH O CM Ph to 0 • tJo

jd+>©E

*»©m

ViOo o©

jd

+>

>* .0

+3aop

«dpH©h



PRESTRESSED SLAB - 1

TABLE NO. 2 COMPARISON OP STRESSES IN EACH WIRE OP EAST PRETSSIN3T PRSSTRESSIN3 UNIT

TOTAL

TENSION

BT

DTNAMOMETER

STRESS

INDICATED

BT

DYNAMOMETER

STRESS IN WIRE HEMABIS:

NO. 2 HO. 3

NO. 4 NO. 5 NO. 6 NO. 7

$36 to NO. 9 NO. 10

KIPS PSI PSI PSI PSI PSI PSI PSI PSI PSI PSI /

5.00 16,540 29.980 25. **90 25.570 25.750 22.550 18,020 34,420 18,680 25.430 FRESTRESSIN8

STARTED

10.00 33.O8O 48.900 46,4oo 46,200 47,600 42,200 39,000 58.700 40,900 47.300

15.00 49,620 62,700 58,800 57.800 59.900 53.300 51.100 73.4oo 56,200 62,300

18. 50 61,200 76,500 72.300 70.900 73.200 66,500 64,500 84,600 70,100 75.500

18.20 60, 210 77.000 72,100 70,100 72.300 69,000 67,200 89.500 73.200 77.500

17.30 57.230 73.300 69,000 66,000 68,100 65.300 62,500 69,400 73.300 BEFORE MOTINO

TO TEST SITE

16.00 52.930 70,400 65.700 63,000 65,100 62,400 59.700 — 66,4oo 70,400 START OP TEST

16.20 53.590 70,900 66,300 63,000 65,200 62,400 60,200 66,900 71,200

16.35 53.920 71.780 65.900 63.500 65,900 62,800 61,100 — 67.700 71.780

16.60 54,910 72. 800 66,400 64,200 66,600 63,500 62.000 — 68.500 72,800

16.80 55.570 74,200 67.000 65,000 67.300 64,500 63,300 69,500 73,800

18.60 61.530 80,300 72,000 64,800 73.000 69,500 1 69,600 — 75.500 79.800

21.70 71.760 93.500 83,800 81,700 85,200 80,600 80. 700 — 88,100 91,600

22.60 74. 760 93.700 84,300 82,300 85,600 81,200 81,200 88,800 92,000

26.20 86,670 106.300 96,800 94, 700 98.700 93.700 93.200 — 102,000 104,700

NOTE: Stress In wire was eomputed from S = E. , where E a 29.6 x 10^ pel and < «= .strain Indicated By SR-4 Bonded wire gages on each wire.


'
PRESTRESSZD SLAB - X

TABLE HO. 3 COMPARISON OP STRESSES IH EACH WIRE OP WEST PREYSSINET PHESTHESSING UNIT

TOTAL

TENSION

BT

DYNAMOMETER

STRESS

INDICATED

IN

DYNAMOMETER

STRESS IN WIRE REMARKS:

NO. 12 NO. 13 NO. 17 NO. 18 NO. 19 NO. 20

KIPS PSI PSI PSI PSI PSI PSI PSI

5.00 16. 540 25.500 23.500 26,300 22,100 23.600 28,000 PRESTRESSINO

10.00 33.080 45,100 41,500 46,100 4i,4oo 43,700 47,200

STARTED

15.00 49.620 55.700 50,900 58,000 53.800 55.400 61,800

IS. 20 60,200 68,700 63.900 70,700 66,4oo 67,800 74.700

17-90 59.200 92.300 88,600 31.500 86,300 84,400 91,800

16.90 55.900 88,500 81,900 29,200 81,900 80,700 88,000 BEIORE MOPING

15. so 52.300 84,500 78.500 28,200 78.500 77.100 83,800

TO TEST SITE

START OP TEST

16.00 52.900 85.200 79. *<oo 28,800 79.200 77,800 84,600

16.20 53.600 86,000 79.900 29,600 79.900 78,4oo 85,400

16.50 54.600 86,900 80,700 30.500 80,700 79.300 86,300

16.90 55.900 88,100 81,900 31.500 81,800 80,600 87.500

18. 60 61,500 94,100 88,700 37.900 88,100 86,700 94,100

21.90 72,400 — 100,800 50,000 99.700 97.900 106,000

22.60 74,800 — 101,500 51.000 100,400 98.700 106,600

26.00 86,000 113,800 64,300 112,100 109,600 106,300

NOTE: Stress in wire was computed from S = E« , where E «= 29.6 x 10^ psl and c = strain indicated by SR-4 bonded wire gages on eaoh wire.



PRESTRiSSSEU S-U&D - i.

TABLE NO. 4 STRAINS IN TRANSVERSE SECTIONS AT CENTER AND QUARTER POINTS

(MICROINCHSS/INCH)

CAGE PRESTRESS LOAD - KIPS APPLIED LOAD - PSP

NO. 5 10 15 18.

18.05 17.1 16.75 0 10 20 30 4o 50 60 70

TRANSVERSE SECTION AT CENTER

18 4 22

19 4 21

- 7-5

-11.5

- 3-5

- 8.5

l4.o

-20.0

-12.5

-21.5

4. 4.5

- 7.0

*-13.5

- 1.5

4-71-5

4-28.5

-90.5

-80.

4- 92.5

a 89.5

4. 94.0

4- 78.5

4- 93-5

- 76.5

4- 93.0

- 35-5

* 75.0

- 57-0

4- 60.5 - 2.5

20 -13.0 12.0 - 22.0 -25.0 -10.0 4-54.0 4- 92.0 4-92.0 4.173.0 4-221.0 4- 252.0 4-311.0 4-322.0 4-368.0 4- 351*.o

46 4 Us 7-0 -17-5 -22.0 -24.5 - 14.0 -33.5 4- 2.5 4-44.0 4- 89.5 4-107.5 4-119.5 4-145.5 -244.0 4-383.0 4-534.0

^7 13.0 -14.0 - 22.0 - 24.0, -31.0 -24.0 4-16.0 4-39.0 4- 75.O 4- 62.0 - 38.0 - 68.0 - 110.0 156.0 -186.0

AVERAGE TRANSVERSE SECTION AT QUARTER POINTS

10,34 4

6.30 - 9.2 - 8.7 -15.0 -15.2 - 0.7 4-I6.O 4-65.5 4-85.0 4- 89.5 4- 88.0 4- 85.5 4- 81.

4. 83.0 4" 56.7 . 37-2

9.33 * -10.7 -10.5 -13.5 17.0 4- 7.0 4-28.2 -87-5 4- 88.0 4- 77-7 4- 68.7 4- 52.5 _ 26.2 7.31

8 4 32 - 15.0 -13.0 - 22.0 - 22. 0

' - 6.5 4- 8.0 4-62.0 -99.0 4-132.5 -146.5 .-158.5 ..172.0 4179.5 *164.5 4.221.0

42 , 54 &

4o, 52 - 30.0 - 34.0 - 38.5 - 41.2 - 30.5 - 40.5 4. 6.7 4-32.7 4- 75.5 4- 95.0 4-102.5 4-114.7 4-152.5 4-248.2 4-352.0

4l 4 53 - 4.0 - 8.0 -11.5 - 10.5 0 - 8.0 4-46.0 4-48.0 4- 81.0 4. 68.0 4- 46.5 . 15.0 _ 100.0 _ 120.0 - 172.5

LOCATION 0? CAGES

u

u

©

NOTES PLUS VALUES INDICATE COMPRESSION.

MINUS VALUES INDICATE TENSION.

<NBS>

Fig.

1

-

Overall

View

of

Form

Placement

of

Steel

in

Form
22 6

^
Pig.

3

_

Sliunp

Test

of

Concrete

Mix

Tir. h - Close Up View of Section of Sage Beam Showing Detail of Cages.

tgrjt

Fig.

5

-

Arrangement

of.

SB-4

Strain

Gages

on

Freyssinet

Prestressing

Unit.
4
Hydraulic

Jacks

in

Place

for

Prestressin?-.

fr * , •'"rH

Fig. 7-

Overall

View

of

Lifting

Jig

and

Test

Specimen.
<r tJ
Overall

View

of

Specimen

at

Start

of

Test

^ r ’* 9 ** Crack Pattern in Section Of.' East Edge Bea i - 70 r°F (First Oracle, Opened at Approx. 45 PSF) : HB



Fig.

11

-

Overall

View

Showing

Failure

at

BO

PSF.

Fig.

12

-

Close

Up

of

Secondary

Failure

in

N.E.

Corner

of

Specimen.

o

LlI >

CH

LU
% LZ?
AVERAGE

OBSERVED

TENSION

IN

PRESTRESSING

UNITS,

KIPS

rntb I KtooLU DLMD- i

VARIATION 'OF AVERAGE OBSERVED TENSION IN PRESTRESSING UNITS WITH APPLIED LOAD

DEFLECTIONS

UNDER

APPLIED

LOAD

0

post

TENSIONING

AS MEASURED BY MICROMETER DIAL GAGES

FIG. 14

DEFLECI

I

UIM o

UNDER

APPLIED

LOAD

a

POST

TENSIONING

UNIFORM LOAD LOAD IN STRE5BW

FINAL

PRECAST- PI^ESTRESSED SLABI

DEFLECTION OF WEB AT CENTERLINE UNDER POST TENSIONING ft APPLIED LOAD

AS MEASURED BY MICROMETER DIAL GAGES

FIG. 15



DEFLECTION

UNIFORM LOAD

PO£T (TEN 3ION1NG

SECTION AT

PRECAST - PRESTRESSED SLAB -

DEFLECTION OF CROSS-SECTIONS UNDER APPLIED

LOADS AS MEASURED BY MICROMETER DIAL GAGES

FIG 16

APPLIED

LOAD,

PSF

60

50

40

30

20

I 0

0

r r\c o i ncoocu OLAd 

I

APPLIED LOAD VS. DEFLECTION OF EDGE BEAMS AT CENTER AND QUARTER POINTS

AT CENTER AT QUARTER POINTS

AVERAGE DEFLECTION OF EDGE BEAMS. IN.

-'i. FIG 17 TT

j

;

;

LI:

• —i— iiilUi:.:.. . ;.i:

:

1

;

i II:

“T~ '

•

.... .

ILl

' -

:

: r -

”T

;

.

:

.

‘ X

’

. r* ”jr .

. - : i

-

. ri

:

i

L i

. i r t

:

1

_.:j

•

'

1

j

j

f \r

i i’rrlnL

/

:

/

:

.

• /

i'

'

. : L

’ '

,

1

L

|

; x

> j

.

:

l

1 1



CO

LU

X

CJ

o

UJ

0

I

2

3

4

5

PRESTRESSED SLAB

DISTRIBUTION OF DEFLECTIONS UNDER APPLIED LOAD

(DEFLECTIONS MEASURED WITH TAUT WIRES)

5* e-iyeu

ZERO LOAD

60 1-1/2 HOURS LATER

c 1

'

j-

. .j: 'J

-o- = FIRST DAY OF TEST

X-- SECOND DAY DF TEST

NOTE: F GURES ON CURVES

INTENSITY

: i*

OF APPLIED LOAD

;

6



n

!

B

D

E

[

O

ni/ni 9.01 'Nivais nvNiarui9Non

NOTE--

NUMBERS

ON

CURVES

INDICATE

LOAD

ON

SLAB

IN

LB/SQ

FT.

COMPRESSIVE

STRAINS

ARE

PLOTTEO

BELOW

ZERO

LINES.



TRANSVERSE

STRAIN,

I0

-6

IN.

/IN

PRECAST-PRESTRESSED SLAB1

DISTRIBUTION OF TRANSVERSE STRAINS

FIG. 20

NOTE: NUMBERS ON CURVES INDICATE LOAD ON SLAB IN LB/SO FT.

COMPRESSIVE STRAINS ARE PLOTTED BELOW ZERO LINES.



PRESTRESSING

FORCE

APPLIED

LOAD

KIPS

PSF

PRESTRESSED SLAB -I LONGITUDINAL COMPRESSIVE STRAINS THROUGH TENSIONING AND LOADING CYCLE AT TOP OF SPECIMEN

STRAIN



PRESTRESSING

FORCE

APPLIED

LOAD

KIPS

PSF

PRESTRESSED SLAB-1

LONGITUDINAL COMPRESSIVE STRAINS THROUGH TENSIONING AND LOADING CYCLE AT BOTTOM OF SPECIMEN

(CENTER SECTION)

-EDGE BEAM

FIG. 22

INTERSECTION OF EDGE BEAM AND WEB LWEB AT CENTER

—.0002 ^

STRAIN



PRESTRESSING

FORCE

APPLIED

LOAD

KIPS

pcc

rnCO I nLOJLU OL AD I

LONGITUDINAL COMPRESSIVE STRAINS THROUGH TENSIONING AND LOADING CYCLE AT TOP OF SPECIMEN

^AVERAGE OF QUARTER POIN T SECTIONS)

INTERSECTION QE EDGE BEAM AND WEB WEB AT CENTER

STRAIN

\

PRESTRESSED SLAB -l

FIG. 26

7

6

5

4

3

2

I02 6 10 14 18

STRAIN, I0"

4

IN./IN.

67 6 0 PSt

o

i

ntoa,

iu

roi

PRESTRESSED SLABI

FIG. 27

14441 --lit

STRAIN, 10 IN./IN
- f
PRESTRESSED SLAB-1

FIG. 28

TENSION

STRESS = 87,500

l 84B

i-r

i

-1

t

1

-(TfI

0 8 16 24 32 40

STRAIN, I0‘ 4

IN./IN.
.
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act

of Congress, March 3, 1901, as amended by Congress in Public Law 619, 1950.

These include the development and maintenance of the national standards of

measurement and the provision of means and methods for making measurements

consistent with these standards; the determination of physical constants and

properties of materials; the development of methods and instruments for testing

materials, devices, and structures; advisory services to Government Agencies on

scientific and technical problems; invention and development of devices to serve

special needs of the Government; and the development of standard practices,

codes, and specifications. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services

and various consultation and information services. A major portion of the

Bureau’s work is performed for other Government Agencies, particularly the

Department of Defense and the Atomic Energy Commission. The scope of activities is suggested by the listing of divisions and sections on the inside of the

front cover. Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and

devices or published papers and reports. Reports are issued to the sponsoring

agency of a particular project or program. Published papers appear either in the

Bureau’s own series of publications or in the journals of professional and scientific

societies. The Bureau itself publishes three monthly periodicals, available from

the Government Printing Office: The Journal of Research, which presents complete papers reporting technical investigations; the Technical News Bulletin, which

presents summary and preliminary reports on work in progress; and Basic Radio

Propagation Predictions, which provides data for determining the best frequencies

to use for radio communications throughout the world. There are also five series

of nonperiodical publications: The Applied Mathematics Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous Publications.

Information on the Bureau’s publications can be found in NBS Circular 460,

Publications of the National Bureau of Standards ($1.00). Information on cali- bration services and fees can be found in NBS Circular 483, Testing by the National

Bureau of Standards (25 cents). Both are available from the Government Printing Office. Inquiries regarding the Bureau’s reports and publications should be

addressed to the Office of Scientific Publications, National Bureau of Standards,

Washington 25, D. C.
NBS