i an investigation of rail- to - concrete fasteners · fig. i — insulating systems for rails...

PORTLAND CEMENT ASSOCIATIONRESEARCH AND DEVELOPMENT LABORATORIES

I AN INVESTIGATION OF

RAIL- TO - CONCRETE FASTENERS

By T. T. C. Hsu and N. W. Hanson

Reprinted from the Journal of the PCA

Research and Development Laboratories

Vol. ! O, No. :3, 14-35 (September 1968)

@ por~land Cement Association, 1968

AN INVESTIGATION OF

R,AIL-TO-CONCRETE FASTENERS

By T. T. C. Hw and N. W. Hanson

PORTLAND CEMENT ASSOCIATION

RESEARCH AND DEVELOPMENT LABORATORIESOld Orchard Road

Skokic, Illinois 60076

T. T. C. Hsu N. W. Hanson

An Investigation of Rail-to-Concrete Fasteners*

ByT. ‘T. C. Hsu, formerly Research Engineer, HIGHLIGHTS

andNorman W. Hanson, Senior Research

EngineerStructural Research SectionResearch and ]Deve[opment LaboratoriesPortland Cement Association

SYNOPSIS

Prestressedconcrete railroadties are being increas-ingly used. This investigation deals with the rail-to-

c.oncrete fasteners for concrete ties, bridge decks, and

tunnel linings. For spring-clip fasteners in concrete

ties. three mefhods of electrical insulation were stud.ied. These fasteners were su~ected +.s tie-wear tests,

longitudinal-slip tests and electrical-resistance tests.

The anchors usecl were also subiected to pullout tests.For fasteners in bridges and tunnels, three differen+fasteners were hasted under repeated loading. In ad-

dition, the “seccmd-cast’m method of construction wasstudied.

KEY WORDS: onchors; concrete railroad ties; elec-trical insulation: electrical resistance: longitudinal slip:pullout }s.s+s: rail fasteners: railroad ties: repeated

loads; testing

●The preparation of a part of this report hasbeen financed through a mass transportationgrant from the Department of Housing andUrban Development under the provisions ofSection 6, Public Law 88-365,88th Congress,asamended.

The economy of concrete ties has im-proved in recent years. A 1966 studyf 1)**by the Chesapeake & Ohio and the Balti-more & Ohio Railroads showed that undermany conditions it is more economical toinstall concrete than timber ties. Recent de-velopments in mass transportation systemsfor large cities, such as San Francisco andChicago, have also focused attention on theuse of concrete ties. The San Francisco BayArea Rapid Transit District (BARTD)surface tracks will be supported[ on 146,000concrete ties (69 miles of track). Similarly,contracts for the surface extension lines ofthe Chicago Transit Authority call for con-crete crossties.

Rail Fasteners for Ties

One of the technical problems of con-crete ties has been development of suitablefasteners to connect the rail to the tie.Using rails to transmit electrical impulsesthat control modern signal syst(ems severelylimits the amount of electrical leakage thatcan be tolerated between the two rails of atrack. One way to reduce this leakage is touse fasteners that insulate the rail from theconcrete ties.

* *NUmbers in parentheses designate references at

end of paper.

14 Journal of The PCA Research and

Static and repeated load tests were car-ried out on four spring-clip fastener assem-blies to evaluate three ways of providingelectrical insulation. In addition, electricalresistance tests ancl pullout tests were madeboth on the rail fastener assemblies and onindividual anchors. The three ways of pro.vialing insulation are shown in Fig. 1. Plas-tic parts and coatings are used as insulat-ing barriers between the rail and the con-crete block representing the tie.

All fastener assemblies tested passed thesevere “tie-wear test.” This test requiresthat no sign of failure be visible after 2.5million cycles of load have been appliedalternately to the gage and field sides of therail.

Longitudinal-slip tests revealed that aZOO-lb-ft torque ‘was required on lubricat-ed anchor bolts to provide sufficient raiIclamping fcm all fastener assemblies to passthe minimum specified slip Ioadof 3.5 kipsper fastener.(z)

After completion of the mechanical tests,electrical resistance measurements weremade on the concrete tie blocks. Underconditions simulating dry weather, themeasured resistance for three of the fourspecimens was greater than 100,000 ohms,which is more than adequate. However,drenching with water to represent rainyweather reduced the electrical resistance ofall fasteners. The best fastener had anepoxy-coated anchor and an insulatingplastic pad under both the rail and clip; itretained a resistance of about 10,000 ohmsbetween the two rails. This resistance ex-ceeds the 4000-ohm resistance needed tomeet minimum requirements.

Pullout tests c)f fastener assemblies andanchors indicated that, although the indi-vidual anchor strength was as high as ex-pected, the pullout strengths of the fullassemblies were below the severe AREAProposed Specifications z) requirement of18,000 lb.

Bridge and Tunnel Rail Fas+eners

Three rail fasteners designed to providethe cushioning and electrical insulation

NYLON PADBOLT

,JJ,SYSTEM A

DOLT, 4)NYLON THIMBLE,

IL–21

1-l SYSTEM B

I

BOLT

Fig. I — Insulating Systems for Rails lJsing

Spring-Clip Fasteners.

necessary between rail and bridge decks

(Fig. 2) or tunnel linings as required foruse in the San Francisco BARTD (3) were

tested under repeated loads. For one of the

fasteners, the complete construction proce-

dure was carried out by first casting a level-

ing course of corterete between a hardened

concrete base and the rail fastener assem-

blies.( 4) Tests were performed on the whole

assembly. The three fasteners successfully

withstood the stiffness and repeated load

tests they were subjected to.

RAIL IFASTENERS FOR CONCRETE TIES posed to the American Railway Engineering

Of the many Tail fasteners used through-Association.(z) This fastener appears to be

out the world, the one currently suggestedsimple and economical. Since the clip is not

for use in the United States is the springproprietary, the present tests of methods toinsulate the rail from the concrete tie were

clip described in the Draft Specifications pro- carried out on this type of fastener.

Development Laboratories, September 1968 15

Fig. 2 — One Rail-Fastening System for Bridge Decks,

Uti!izing a Seconcl-Cast Method of Construction.

The test specimens were manufacttsredand tested at the Structural Laboratory ofthe PGA Research and Development 13ivi-sion. They were first subjected to the weartest and longitudinal-slip test required bythe .AREA Proposed Specifications tzJ forrail fastener assemblies. In addition, elec-trical res~stance tests and pullout tests weremade both on the rail fastener assembliesand on the individual anchors used in thetest s ecimens.P

Insulation Methods

Th,ree ways of insulating the rail wereconsidered for the spring-clip type of fas-tener. These are shown in Fig. 1.

System A was suggested in the AREAProposed Specifications.(z) Here; one insu-lator (a ~ ~-in.-thick polyethylene pad) isplaced under the rail, while a second insu-lator (a ~~-in.-thick nylon pad) is placedbetween the rail and the clips.

In System B, the polyethylene pad underthe rail is extended under the clips. Theother ins ulator (a 3~1~ -in.-thick nylon thim-ble) is placed between the clip and the

TABLE I — FASTENER SPECIMENS TESTED

ITm——— 1. F@. 1 shows Configuration for each type of spec, men.fil~ig. z ~hO~~ the two types of anchors.

bolt washer. The washer is needed to dis-tribute the bolt force over the nylon thim-ble.

In System C, the polyethylene pad underthe rail is again extended under the clips.With this system, the anchor is coated withan insulating material. Both polyethyleneand epoxy were evaluated as insulatingmaterials. BULLETIN 224( ~)* reports electri-cal tests made on coated anchors embeddedin saturated concrete and shows that thesecoatings greatly improve the electrical resis-tance.

Details regarding each specimen are giv-en in Table 1.

Description of Specimen Parts

The spring clips used in the four speci-mens were made by hot. bending 1/4x 3-in.strip steel bar and then heat-treating to sat-isfy Section C5 of the AREA ProposedSpecifications.t z) SAE 1095 sleel was usedrather than the SAE 1090 steel suggested bythe Proposed Specifications. Although noclip tests as described in Section 143(a),(b), (c) and (d) of the AREA ProposedSpecifications were made, the clips per-formed well during the mechanical tests ofthe fastener assemblies. No failure in theclips was observed. Hightrength 2/4-in.-di-ameter bolts satisfying Section (:8 of theAREA Proposed Specifications were used inall specimens.

*PCA RESEARCH AND DEVELOPMENT DEPARTMENTBULLETINS will be identified in the text primarilyby the BULLETIN number.BULLETINS are availableon request in the United StatesandlCanada.

Journal of The PCA Research and

TvJo types of commercially available an-chors were employed. The first type, shownin Fig. 3(a), is manufactured by bending a3 or 2-in.-wide stainless steel plate to forma cylinder Withl a flared end. Threads arethen cut inside the cylinder. The secondtype, shown in Fig. 3(b), consists of a 1~8-in.-Iong closed cylinder that has a steel wireloop welded to it. This anchor is also inter-nally threaded. Type I anchors 1T/8and 27/sin. km$ were used in Specimens I and H,respectively. In Specimen HI, the T’ype Hanchors were covered with a 0.027-in.-thickpolyethylene coating. This coating was verysoft and could be indented with a finger-nail. In !Ipecim.en IV, the Type 11 anchorswere covered with a 0.023-in.-thick coatingof a. commercial epoxy protective resincalled ‘ ‘S,cotchkote.>’ This coating was veryhard.

Polyethylene pads that were ~1e in. thickand 7 in. wide were placed beneath therails in the test specimens. These pads metboth AS’TNf Specification D 1248,[ G] Type11, Grade 3, G] ass B and Seciion C7 of theAREA Proposed Specifications. tZJThe padsused with Specimens II, HI and IV wereshaped in the PCA Laboratories by press-ing a ffat sheet between a pair of hardwoOdmolds and holding this in an oven at atemperature o E 280 F for two hours. ‘Thecontour of the hardwood mold was ma-chined to fit the spring clips. The resultingmolded pad is shown in Fig. 4.

The nylon pads in Specimen I and the

ny~On thimbles in Specimen 11 were madeof Nylon 66 (Zytel 101). This materialconforms to both ASTM Specification n D789,( ?) Type I, Grade 4 and Section C,6 ofthe AREA Prclposed Specifications. fz) Boththe pads and the thimble were machinedfrom a single piece of material. The di-LTKnSiOnS of the pads shown in Fi~. 5, con-form to Fig. 5A of the AREA ProposedSpecifications.(’)

The concrete tie blocks were made withair-entrained concrete having a cylinder

strength of about 7000 psi at 28 days. Di-mensions and. reinforcement details areshown in Fig’. 6. The 7 x 9-in. cross sectionunder the rai [ is roughly the same as forcommercially available concrete ties. Thecontour of the upper surface, shown in Fig.6, is designed to fit the spring clips and thepolyethylene ]pads.

\

.

(a) Type 1Anchor (2% hr. Lorw)

(b) Type II Anchor

Fig. 3 — Types of Anchors Used.

Fig. 4 — Polyethylene Pad and Concrete TieBlock Used in Specimens II to IV.

Developrnnenf Labalratories, September 196817

NYLON BID

(SPECIMEN I )

NYuJN 7HIMEILE

(SPECIMEN II 1

@

.— t .— .—

,

Fig. 5 — Nylon Pad and Nylon Thimble.

Tie-Wear Test

‘Tie-lVear Test Rig. The four specimenswere tested in a specially designed tie-weartest rig. A general view of the rig is shownin Fig. 7, whi [e Fig. 8 shows its details. Theloading scheme for the rail fastener, shown

Fig. 7 — Gelneral View of Tie-Wear Test Rig.

Fig. 6 — Concrete Tie Block.

in Fig. 9, meets requirements of SectionH4(a) of the AREA Proposed Specifica-tions.(z)

Loads were applied alternately to thegage and field sides of the rail. These alter-nating loads were applied by two 25-tonAmsler rams described in BULLETIN D33.f 8)The rams were attached to the cross mem-ber of a concrete frame which was pre-stressed to the laboratory fioor by two 13/8-in.-diameter high-strength rods,. This testfloor is described in BULLETIN 1>33.(s) Thealternating loads were supplied by twoseparate pulsators connected 180 degreesout of phase by a mechanical coupling.

The hydraulic rams are desig~ed to sup-ply a load that varies sinuso,dally withtime. However, the tie-wear test requiresthe alternating load to be applied in such amanner that each load is completely re-leased before the other load is applied. Toobtain this loading, the combination oframs and springs shown in Fig. 8 was used.At each ram a square tube crosshead is at-tached. Each crosshead is connected by twosteel rods to a spring assembly located ontop of the concrete frame. Each spring as-sembly is made up of four springs sand-wiched between two steel plates. The

springs restrain the movement Of the rams,thereby converting the sinusoidal load intoa half-sinusoidal load.

The load from each ram is transmitted tothe rail through a series of ball lhinges, loadcells, and a specially designed chair. Signalsfrom the load cells are recorded on a San-born 67A continuous strip reccjrder as de-scribed in BULLETINS D33( 9) and D91. (9)Representative output is shown in Fig. 10.It can be seen that the load-v s-time rela-tionship is described by two half-sinusoidalcurves 180 degrees out of phase.

78 .lournal of The PCA Research and

[ RESTRAINING ROD y’j~ I

\k----r-J[ I

--- {.’,. && W“ .

BALLHINGE

1 I‘ill

A

LOAD CELL

CHAIR

RAIL

A

CONCRETE - ‘TIE BLOCK , , ,

REACTION ‘ ‘BLOCK

. .,, r

L. —LsECTION A-A

1

L _.+A

Fig. 9—Details of Tie-Wear Test Rig.

Description of Test. A concrete reactionblock was first tMestressed securely to thelaboratory floor-,-as in Fig. 8. Then”the con-crete tie block was grouted on top of thereaction block with the rail at its intendedposition. After the grout hardened, theconcrete ttie block was tied down to the re-action block by two T/8-in.-diameter rods.The tie block was then ready to receive therail Eastener assemblies.

After the rail clips were in place, thebolts in the assemblies were tighteneddown by a torciue of 150 Ib-ft as requiredby the AREA Proposed Specifications. <z)Application of loading alternately to thegage and field sides of the rail was then be-gun. The loads were applied at a rate ofabout 250 cycles per minute. In the earlystages of the test, it W= necessary to a+~t

the load frequently. The load was keptwithin tiz10 percent of the intended valueat d times.

Torque in tlhe fastener hold-down boltswas checked periodically during the test. Ifthe torque was found to be lower than 150lb-ft, it was brought back up to this value.

21.4 KIPS20.4 KIPS

20 KIPS I

L

GAGE

\/ -

CENTER OF GRAVITY

OF RAIL SECTION

I_____

I

Fig. 9 — Loading Scheme.


Fig. ltI -– Strip Recorder Showing Half-SinusoidalL~adl-vs-Tirne Relationships.

Test Results. The number of cycles aP-plied to each specimen is listed in Table ZAll specimens withstood 2.5 million qyclesof loading without visible sign of failure ofany par]t of the fastener assembly. Cc)nse.quently, each specimen satisfied the re-quirements of Section K14(a) of the AREAProposed Specifications.(z) Although notconsidered seriOUS,hairline cracks were ob-served am-ound the inserts of the concretetie block in Specimen III.

The bolt torque-vs-cycles of loadingcurves {or Specimens 1, H, and IV areshown in Fig. 11. The bolt torque in Speci-men HI was not checked. In Specimen I,the hold-down bolts had to be tightenedfrequently during the test. This may be theresult of movement and deformation of thenylon pad between the clip and the rail.The torque stabilized after 1.9 million cy-cles of loadin~. In Specimen II, much lessadjustment was necessary to bring the bolt

. . .up ~:: the lnltlal torque. specimen Iv wasread~ usted to proper torque only once inthe early stages of loading.

Although all[ the specimens passed the tie-wear test, Specimen IV exhibited the bestoverall behavior. Consequently, system C

appears to be the most desirable way to in-

TABLE 2 — NUMBER OF LOAD CYCLESON IFASTENER SPECIMENS

ks!+wlSpec, men Specimen spec, men specimen

3175000 3617000 3356000 3358000

“~-0 2 3

MILLIONS OF CYCLES

SPECIMEN U

o~.do 2 3

MILLIONS OF CYCLES

u1

3I

oao 50

i-

1

SPECIMEN IX

MILLIONS OF CYCLES

Fig. I I — Torque % Bolts During Test.

sulate the rail so long as the coating on theanchor is sufficiently strong.

Longitudinal-Slip Test

Description of Test. Section H4(b) of theAREA Proposed Specifications :~) requiresthat “the end of the rail in the fasteningassembly should be subjected to a longi-tudinal load of 3500 lb and the movementbetween the rail and the concrete tie re-corded by dial gages reading to 0.001 in.The load of 3500 lb shall remain on theend of the rail for three minutes without


any increase in the rail movement after thethree-minute period.”

After tie-wear tests were completed, eachof the four specimens was subjected to alongitudinal-slip test as described above. Aschematic view o.Ethe test setup is shown inFig. 12!.The concrete tie block was fastenedto the laboratory floor by crossheads androds. Horizontal load was supplied by a 10-ton hydraulic ram that acted a~ainst areaction block. Load was applied to tlhecentroid of the lower flange of the railthrou~h a steel ball. The movement of therail with respect to the concrete tie blockwas mleasured at each load stage by a dialgage after holdi]mg the Ioad for three min-utes.

Test Results. Two sets of longitudinal-slip tests were made. The first set was madewithout lubricating the hold-down boltsbefore they were tightened. The second setwas m[ade after each bolt had been coatedwith Nfolykote, a commercial lubricant, be-fore the bolts were tightened down. A ty]pi-cal loi~d-slip curve is shown in Fig. 13. Fig.14 shows a plot of the load at which com-plete dipping occurred vs the torque on thehold-down bolts.

Fig. 14 shows that for the set of testswithout lubricant the load at completeslipping is extremely erratic. In the processof tightening the hold-down bolts for thesetests, the friction between the bolt and theclip or anchor is large. This friction takesup a Iarge part of the applied torque andprevents achievement of the full tension in-tended in the bc}lts, and the intended hold-ing fc~rce of the fastener. In the set of testswithout Irrbricant, most of the specimensfailed to sustain the 3500 lb of horizontal.load specified in the Proposed Specifica-tions. f z) This was true even when thetorque on the bolts was increased to 300lb- ft.

The resistance to slipping appeared todecrease with increasing torque on thenonlubricated hold-down bolts for Speci-mens I arnd II. Since the sequence of sliptests was made with increasing torque onthe bolt, it appears that the friction be-tween the polyethylene pad and the rail(or between the clip and the rail) de-creased each time the test was repeated.

Mc~re consistent test results were ob-tained in the second set of longitudinal sliptests. For these,, the hold-down bolts werelubricated before tightening. Fig. 14 showsthat one out of four fasteners was able tosustain the 3500-lb horizontal load for

Development Laboratories, Sepfember 1968

three minutes when the hold-down boltswere lubricated and tightened to 150 Ib-ft.However, with the torque increased to 200lb-ft, all four specimens meet requirementsof Section H4(b) of the AREA ProposedSpecifications.(z)

Elecfr;cal-Resistance Test on

Individual Type II Anchors

Two types of electrical resistance testswere made on the Type H anchors shownin Fig. 3(b). The first group of tests wasmade on individual anchors, each coatedwith one of five types of insulating materi-al. The coated anchor was embedded in a4-in. cube of concrete. After the concretehad hardened, the cube was stored in abrine solution. Periodically, each cube was

\ /RAIL

{ L--’Y, REACTION

r /“ BLOCK

STEELZ ‘

/,/,

ANGLE ~CLIP

‘CONCRETE TIE BLOCK//////f/////[

FLOOR

ELEVATION

[

STEEL BALL

PIO–TON RAM

,

“ REACTION~ BLOCK//

CLIP

GE“HE[RAIL

CONCRETE

LE

TIE BLOCK

PLAN

Fig. 12 — Setup for Longitudi.al-SliF, Test.

21

ISPECIMEN NO, IV

TORQUE 200 Ib–ft j

WITH “MOL),KO1-E “ LIJBRICANT

c1g—.. —~ .— -- .1__ .i(102 004 006

SLIP [tn )

Fig. 13 —. Typ?col ~.,oad-Slip Curve.

rcmowecf from the brine, tb e surface waterwas removed, and the electrical resistancewas mea sured. The detailed description

and I!he results of these tests are reported inBULLETIN 224.{5)

It was found that thin coatings of eithernylon or teflon increased the electrical re-sistance only slightly. Coatings such asthese should not be used for electrical in-sulation in saturated mncrete. Coatingsmade wif.h polyethylene, epoxy and vinyli-dene fluoride resins were found to improvethe electrical resistance from a few hundredohms to the order of 100,000 ohms.

Electrical-Resistance Tests on Concrete Tie Ltlock

Descri$)tion c,f Tests. IUectrical-resists ncetests were also made on the concrete tieblocks after completion of the wear tests.These blocks were first saturated with wa-ter by placing them in a room with 100percent relative humidity for four days.Then one corner of each block was chippedoff to expose a longitudinal reinforcingbar. Electrical :resistance was measured un-der three conditions. First, resistance wasmeasured[ between the exposed reinforce-

ment and the two anchors in each saturat-ed, surface-dry concrete tie block. Next, dryfasteners and rail were installed and elec-trical resistance was measured between thereinforcement and the rail. Finally, theelectrical resistance between the rail andthe reinforcement was measured as tap wa-ter was poured on the fastener and rail tosimulate conditions during a heavy rain.

22

Alternating current of 1000 hertz (cyclesper second) and four volts was applied. Theelectrical resistances measured under eachcondition are recorded in Table 3.

Test Results. Table 3 shows that theelectrical resistance between anchors andreinforcement for Test Condition No. 1varies from 100 ohms to 500 ohms forSpecimens I and II. However, the coatedanchors -in Specimens HI and IV had anelectrical resistance between 1;!,000 and1,000,000 ohms. These values compare verywell with those obtained for individual an-chors as reported in BULLETIN 224.L~J Itmust be mentioned, however, that the elec-trical resistance in Specimen III was lowerthan expected from tests of individual an-chors. This may indicate that the polyethy-lene coating was damaged before the elec-trical tests were conducted.

When measurement was made betweenthe rail and the reinforcement in the ab-sence of surface water — Test ‘Cond itiouNo. Z – the electrical resistance exceeded2,000,000 ohms (the maximum resistancewhich can be measured by the equipment)for Specimens I and 11. This indicates thatthe nylon pad in Specimen I and the nylonthimble in Specimen 11 are extremely effec-tive in improving the electrical resistance

‘-t-tSPECIMEN WITHOUT WITH

LU5RICA LU8RICAN

6 – I am:v

% maAa.- lxnn.

5 –LL.1w~CL AREA PROPOSEDi4m

SPECIFICATION

u 3.5F-W3

z’s0u A52 — -- --./;/0 #46 I

o,~300

TORQUE ON HOLD–DOWN BC)LTS (Ib-ft)

Fig. 14 — Load Required to Produce Total Slippagevs Torque on the Hold-Down Bolts.

Journal of The PCA Research

T,4Bt.E 3 —. ELECTRICAL RESISTANCE IN SATURATED CONCRETE TIES

y- .n~g SPec;::;:::,,,

S:z.

L=+ -q

Without Surface Water 100 500 50000

2 Ra!l to Reinforcement WbthoutSurface Water ‘ ~ 2000000 >2000000 10000

~ 3

150000—.

Rail t. Reinforcement With

:2ce ‘“e’ ‘1000 3000 I -4000 5000

‘All wl”es should be m“ltt Pl, ed by 2 to obta, n the electrical resistance between two ,.?,1s o“ a tie

of the dry fastener- assembly. Under thissimilar condition, the electrical resistancefor both Specimen HI and Specimen .[Vwas found to be adequate for practical ap-plication.

In ‘Test Condition TVO, 3 the electricalmeasurement was made between the railand the reinforcement with surface waterpresent. The electrical resistance droppedto 1000 and 3000 ohms for Specimens Iand 11, respectively. Similarly, the electri-cal resistance for Specimens 111 and IVdropped to 4000 and 5000 ohms, respective-ly. It is obvious (hat the presence of surfacewater considerably reduces the electrical re-sistance. Since the electrical path throughthe surface water is longer for Specimens111 and IV than [or Specimens 1 and H, theelectrical resistances of the former twospecnnens are better.

System C using an epoxy coating to instrlate the Type 11[anchor Irom the concretetie and using al pad to insulate the railfrom the tie appears to have the best over-all electrical resistance. Using this system,the electrical resistance between the tworails of a track is roughly 10,000 ohms evenwhen surface water is present. This is con-siderably in excess of the 4000-ohm mini-mum resistance that is generally accept-able.(z)

Pullout Test of Individual Anchors

Dcvcription o] Test. Both Type I andType II anchors as shown in Fig. 3 weretestec[. The 1~&in. -long Type I anchorswere embeddec~ in concrete as receivedfrom the manufacturer. The outer surfacewas covered with a thin layer of paint.However, for the 2~8-in.-long Type I an-chors, two surface conditions were evaluat-ed. I n addition to a pair of anchors withpainted surfaces, another pair was testedthat had the paint removed from the outer

surface before they were cast into the con-crete test blocks.

For Type 11 anchors, the surfaccx of eachpair of specimens were coated with one ofthe five insulating materials: epoxy, poly-ethylene, vinylidene fluoride, tefl on, andnylon. In addition, two uncoated anchorswere tested for comparison.

Pairs of identical anchors were cast inthe bottom of a plain concrete “block ICI in.cleep, 18 in. wide and 48 in. long, “~hedistance between each pair of anchors was24 in. The average cylinder strength of theconcrete was 6830 psi at the time of thepullout test.

The setup for pullout tests is shown inFi~. 15. A specially designed steel framewith a span of 20 in. was placed longitudi-nally on the concrete block. The center ofthe frame was lined up vertically with oneof the anchors. A 30-ton center-hole ramand a 50-kip load cell were placed on thesteel frame. A ~/4-in.-diameter rod waspassed through the ram and load cell andwas threaded into the anchor. The rod wasanchored on top of the load cell by a nutand a bearing plate. The pullout force onthe anchor was supplied by the ram andwas monitored by the load cel~ connectedio a portable strain indicator using pro-cedures described in BULLETIN D33. ( g)

The vertical displacement of the anchorwas measured by a dial gage reading to0.0001 in. The dial gage was mounted on alight-gage steel bridge clamped securely tothe sides of the concrete block and was fit-ted with a z-shaped needle that restedagainst the wall of the anchor.

Test Results for Type I Anchors. Resultsof the pullout tests of anchors arc summa-rized in Table 4. For the 1T/8-in.-long TypeI anchor, the pullout strength averaged 6.6kips, for the 2~8-in.-long Type I anchor 12.6kips. No difference in pullout strength at-

Development Laboratories, Sepfember 1968 23

Fig. 15— Pallout Tests of Individual Anchors.

I I

.03 .04“o .01 .02

VERTICAL DISPLACEMENT (in.)

Fig. 16—Load-Displacement Curves of Type IAnchors.

24

tributable to paint on the outer :sttrface ofthe anchor was detected. However, the ver-tical displacement of the painted anchorwas about twice that of the unpainted an.chor at all load stages. This is show by theload-displacement curves in Fig. 16. Ap-parently, the paint causes additional slip-ping due to reduced friction between theanchor and the surrounding concrete.

For 17/8-in.-long painted anchors, failureoccurred by pulling out a cone of concretearound the anchor. This cone has beenturned upside down for photo,qaphing,and appears to the right of the crater fromwhich it was removed in Fig. 17(a). For2~g-in.-10ng painted anchors, however, fail-ure was caused by splitting of the concreteblocks as shown in Fig. 17(b). Finally, thefailure of the 27/8-in.-long unpainted an-chors was caused by tearing off d] e top sur-face of the concrete block as shown in Fig.17(C).

Test Re.mlts jor Type II A nchor.~. ForType H anchors, Table 4 indicates that thevariation in stren@l among anchors withepoxy, nylon, wnylidene fluoride, andteflon did not exceed Y 10 percent. Conse-quently, the effect of these four coatings onpullout strength is considered insignificant.

Fig. 18 shows that the load–displacementcurves for epoxy-coated and uncoated an-chors are nearly identical. Similar load–dis-placement curves were recorded for anchorswith vinylidene ftuoride, nylon, and teffoncoatings. Consequently, it can be conclud-ed that these four coatings — epoxy, vinyl-idene fluoride, nylon and teflon -– have noimportant effect on the load-vs-displace-ment relationship of Type II anchors.

In contrast, loads in Table 4 indicatethat the polyethylene coating somewhat re-duced the pullout strength. Fig. 18 showsthat the displacement of the anchor withpolyethylene coating is many times that ofthe uncoated anchor at all load sc:Ses. It isaPParent that a soft and thick coating, suchas polyethylene, will reduce the pulloutstrength and greatly increase the displace-ment.

According to the manufacturer’s specifi-cations, the Type II anchor is rated at 9600lb, approximately the breaking strength ofthe wire loop. This value is very close tothat obtained for polyethylene-coated an-chors. It appears that the soft polyethylenecoating does not contribute significantly tothe pullout strength. The failure mode,shown in Fig. 19(a), indicates that thepolyethylene-coated anchor slipped out of

Journal of The PCA Research and

the concrete block with little resistancefrom the surrounding concrete.

Fig. 19(b) shows that when the epoxy-coated anchor was tested a cone of concretesurrounding the anchor was pulled out ofthe concrete block. The cone is pictured inan invtx-ted position to the right of the re-

(0) Pointed Anchor, 1~ in. Long

(b) Pai,lted Anchor, 27’8 in. Long

[c) Unpainted Anchor, 278 in. Long

Fig. 17 — Pullout Failure of Type I Anchors.

Development Laboratories, Sepfember 1968

maining crater in the figure. This accountsfor the pullout strengths of epoxy-coatedanchors being significantly higher than thespecified value of 9600 lb.

The coating of Type II anchors with astrong insulating material, such as epoxy,has no significant effect on either the pull-

TABLE 4 — PULLOUT STRENGTI-I OF ANCHORS

Pullout strength (klps) I

I Anchor I AnchorType of Specimen .%eclmen I AverageCoating No. 1 No. 2 I

Type 1 Anchor. 17A in. long ~ I

Painted I 6.7 I 6.5 I 6.6 I

Type 1 Anchor, 278 in. long “

Palmed 12,5 12,4 II 12,4Unpainted 12,8 12.7 12.8

Type II Anchorz I

WIaAnch Ors are shown in Fig. 3.

&_L_&-&~30 .01

VERTICAL DISPLACEMENT (in.)

Fig. 18 — Load-Displacement Curves of Type IIAnchors.

25

-{Q) Polyethylene-Coated Anchor——

(b) FpoV-Co.ted Anchor

Fig. 19— Pullout Failure of Type II Anchors.

out strength or the displacement relation-ship. However, a soft coating c[oes reducethe capacity and should be avoided.

Pullout Test of Anchors in Concrete Tie Blocks

~esc~i~t;on of Test. Pullout tests of an-chors in concrete tie blocks were made asdescribed in Section H2(b) of the AREAProposed Specifications.f z) A general viewof the test setup is shown in Fig. 20. Arail two feet long was attached 10 the con-crete tie block by the fastener assemblies.The two ends of the rail were supported bytimber blocks so that the concrete tie blockwas suspended above the floor. A steelframe with a span of 20 in. was placed onthe concrete tie block over the rail.

Load was applied to the frame through asystem of crossheads, rams, and Itie rods at-tached to the laboratory floor. The loadwas calculated from the oil pressure of theram, taking into account the dead weightof the equipment. At the time of test theconcrete strength of the blocks was some-what greater than 7000 psi.

Test Results. The failure loads, P, inpounds, determined by pullout tests of an-chors in concrete tie blocks are recorded inTable 5.

The force between the field clip and therail base, R, and the force in the field bolt,Q, can be calculated from the pullout load,P, by equilibrium of forces using the leversystems illustrated in Fig. 21.

R=P Z ==0.542P1.688 + 2

~=R 2.313+ 1.25

1.25==2.85 R == 1..54P

TABLE 5 — PULLOUT TESTS OF ANCHORS IN CONCRETE TIE BLOCKS

—.—— ——Force or Load, lb

—.—Specimen ! specimen 11 specimen Ill Specimen Iv

Anchor Type 1. Anchor Type 1, Anchor Type II, Anchor Type 11,

Kind of Force or Load 1y8 In. Long 278 in. Long Polyethylene-Coated EPnxY-Coated—.— —

Total Pullout LOad, P 3930 f 6800 6110 9 !2$30

Force Between Field Clipand Rail 8ase, ❑ 2 440 9 120 3 SZo , 4,0

FOrGe in Field Bolt, Q 6100 20 Oou 9460 15450

Pullout Strength 011IndividualAnchors (Table 4) 6 eoo 12450 9650 12400

— —


Fig. 20— Pullou+ Test of Anchors in Concre+eTie Blocks.

Calculated values of R and Q are aIsO list-ed in Table 5.

For Specimens I, III, and IV the failureforces in the lield bolt, Q are reasonablyclose to the pullout strength of individualanchors as lifsted in Table 4 and alsorecorded in the last line of Table 5. The fail-ure modes of anchors in these three speci-mens are also similar to those in cm--responding pullout tests of individualanchors. The concrete tie blocks after thepullout tests were completed are shown inFig. 22.

The failure force, Q = 26,000 lb, in Speci-men II, Table 5, was about twice the aver-age pullout strength of 12,450 lb of the in-dividual Type I, 27/&in. anchOr. The 27/8-in. length of this anchor is enough to reachwell beneath the top reinforcement of theconcrete tie b] ock. The individual pullouttests in plain concrete indicated that fail-

i /115-lb RAIL

FIELD

Fig. 21 — Arrangement of Rail, Clips and Bolts

for 115-lb RE RAIL.

ure is caused by either splitting the blockor tearing the top layer of comx-ete. Topreinforcement apparently helped preventthese two types of failure. Consequently,the pullout strength in the concrete tieblock was higher than that of individualanchors in plain concrete.

Section HZ(b) of the AREA ProposedSpecifications requires that the total pull-

out strength of the rail fastening assembly

shall be not less than 18,000 lb. Table 5

shows that none of the anchors satisfies this

severe requirement. The AREA Proposed

Specifications apply to prestressed concrete

of slightly higher strength (8000 psi) than

was used in these nonprcstressed test speci-mens. Even so, the pullout strength of the

assembly is much less than the sum of the

strengths of the two anchors. This is be-cause the forces on the anchors of a com-

plete fastening assembly are magnified

through the lever system described above sothat the force on each bolt is much greater

than one half the load on the rail.

Fig. 22 — Concrete Tie Blocks After Pullout Test.


RAIL FASTENERS FOR BRIDGES AND TltNNELS

Fig. 23-- Bonded-Elastomeric Fastener.

Fig. 24 — Spring-Clip Fastener.

Fig. 25 — Forged-Clip Fastener.

On bridges and in tunnel[s, rails aresometimes connected directly to concretedecks. For the system used in the Bay AreaRapid Transit District (BARrD) in SanFrancisco, the requirements for such a fas-tener include cushioning of the rail againstvibration in addition to electrical insula-tion, strength, and adjustability. In thisrail system, the fastener is clamped to therail, and the base of the fasteuer is boltedto anchors embedded in a “second-cast”leveling course of concrete as shown inFig. 2. The concrete is leveled against theupper surface of the bridge or the tunneIlining. f4J

Three different types of fasteners weretested for this application. Two of the fas-teners were subjected to the tie-wear testdescribed earlier in this report while thethird was subjected to a push--pull test torepresent the “wave action” caused bywheel loading. For the third fastener thecomplete procedure of the proposed “sec-ond-cast” method of construction was alsoinvestigated.

Descrip+icm of Fastener.

Bonded-Elastomeric Fastenev. The bond-ed-elastomeric fastener shown in Fig. 23consists of a permanent assembly of upperand lower steel plates spaced apart by abonded, elastomeric pad. Steel clips boltedto the upper plate hold the rain in position.The bolting force holds the cli]p fulcrum inone Of a series of surface indentationsspaced I% in. apart in the top plate. The UP-per plate floats on the elastomeric cushionwhich is confined by the two bent-up edgesof the lower plate. Two anchor boltsthrough the plate assembly connect thelower plate to anchors in the concrete base.Electrical insulation is provided by theelastomeric material that separates the up-per and lower plates.

Spring-Clip Fastener. The spring-clipfastener shown in Fig. 24 consists of a steelbaseplate, two spring clips w,ith retainingpins, an elastomeric pad, a polyethylenepad and two Micarta (plastic) inserts withbearing plates and bolts. The rail rests onthe elastomeric pad between shouldersformed in the steel baseplate. Two clipsformed of spring steel bear against the topof the lower flange of the rail to restrain itsmovement. The spring clips are each in-stalled over a short stud welded to the topsurface of the plate.


Spring force is initially created by open-ing the throat of each spring with a spe-cially designed hand tool, The pin is theninserted through holes in the studs. Thispermanently holds the spring force. Twoanchor bolts pass through bearing platesand fitted Micarta inserts to the anchors inthe concrete base. Electrical insulation isprovided by the Micarta inserts and by thepolyethylene pad between the plate and theconcrete base. Various sizes of Micarta in-serts can be used to provide adjustment ofthe rail. position.

Forged-Clip Fastener. The forged-clipfastener shown in Fig. 25 consists of a steelbaseplate, two forged-steel clips with bolts,two elastomeric liners, a polyethylene padand two steel inserts. The elastomeric lineris composed of two identical rubber piecesmolded to match the shape of half thelower part of the rail. This liner surroundsthe lower 31/9in,, of the rail over a 5-in.length.

Both liner and :rail are held in place by asteel clip on each side of the rail and by thesteel baseplate below. Clip bolts secure theclips to the steel baseplate. Two additionalanchor bolts run through steel inserts inthe baseplate and through the polyethylenepad to the anchors in the concrete base.Rail position can be adjusted by usingvarious sizes of steel inserts. The rubberliner provides not only a cushion but alsoelectrical insulation between the rail andthe fastener.

Tie-Wear Tesf

The bonded-elastomeric and spring-clipfasteners were subjected to tie-wear testssimilar to those described earlier in Figs. 7to 10. Since the rail clips on each of thesefasteners are not directly opposite one an-other, loading a rail segment on a singlefastener could cause rotation of the railthat would not be possible in service.Therefore, pairs of rail fasteners placed 1in. apart were tested. The test fastenerswere attached to a precast concrete baserepresenting the bridge or tunnel levelingcourse. Loads were applied to a 115-lb. RErail at a point midway between thefasteners. Alternating loads producing a 30-kip resultant (15 kips per fastener) wereapplied to the test specimen.

Bonded-Elastomeric Fastener. Initialtorque on the raiil clip bolts was 300 Ib-ft.Torque on the anchor bolts connecting thefastener pad to the concrete base was ZOOIb-ft.

15

‘1

. .zCA . .=

L 10. .

zw . .

& . .E

fi . .

a5. .BARTD

2 . . Imttatlon5 of 1/~In _

. .

0 1 ._--—-— I0 005 010

LATERAL DEFLECTION ( irI )

Fig. 26— Load-Deflection Curve for Bonded.Elastomeric Fastener Before Application of

Repeated Loads.

Before the repeated load test began, thefastener assemblies were placed in the tie-wear test rig and loaded statically on thegage side of the rail. The load–deflectioncurve obtained under the loading is shownin Fig. .’26. Lateral deflection of the railhead under the maximum load of 30 kips(15 kips per fastener) was 0.071 in. This iswell within the BARTD limitation of 1/8inO(3)

After the deflection tests were completed,load was applied alternately to the gageand field sides of the fastener. The rate ofloading was 250 cycles per minute. Con-siderable heat was generated during the re-peated load portion of the test. Thetemperature on the surface of the steelreached 108 F, a value that should not beexpected to influence the results of thetests.

After 310,000 cycles of repeated load,vertical cracks about 1A in. long and I\J~in. wide were observed in the rubber be-tween the end of the top plate and thebent-up portion of the bottom plate, How-ever, no change in behavior was observed.

After 1,137,000 cycles, the application ofrepeated loads was temporarily stolpped sothat lateral deflection of the rail headcould be checked. Again static load was ap-plied to the gage side of the rail. Lateraldeflection under the maximum Ic,ad was0.089 in. The increased deflection showsthat the lateral stiffness of the fastener de-creased somewhat from the initia [ value.However, this lateral deflection is still wellwithin the BARTD limitation. The torqueon each bolt was checked and was found tohave dropped about 10 to 30 Ib-ft from the

Development LaboraiLories, Sepfember 196829

0“’5r—~--’-—~-

“o 0.5 I .0 I .5 2.0

CYCLES OF LOADING (millions)

Fig. 27 —. Lateral Deflection vs Cycles of

Loading for Bonded-Elastomeric Fastener.

initial values. Before the test was resumed,these torques were brought back up to the.,, .uutlal value:j,

‘The test was stopped after 2 million

cycles of loading. The lateral deflectionunder the maximum load of 30 kips (15kips per fastener) was 0.092 in, A plot withthe lateral deflection at an applied staticload of 15 kips per fastener on the ordinatevet-sus number of repetitions of load on theabscissa is shown in Fig. 27. This compari-son indicates that the stiffness of thefastener was stabilizing as the test was com-pleted.

.After 2 million cycles of loading thecrack in the rubber between the upper

P!ate of the fastener and the bent-up por-tlcm of the lower plate was about 1 in.long. The maximum width of this crackunder a static load of 15 kips per fastenerapplied on the gage side was somewhatmore than ~le in. It appears that thewidth of this crack accounts for most ofth,e lateral movement of the rail. However,these cracks did not reduce the stiffness be-low that required in the BARTD Speciti-caltions. ( 3)

The fastener pads were subjected to anadditional 10,000 cycles of repeated Ioad, as

described in Addenda 3 amf. 4 of theBARTD Specifications.(g) These Addendarequire that this portion of the test be con-ducted with the anchor bolts connectingthe fasteners to the concrete base on thegage side removed. No undesirable move-ments were observed under this loading,

The bonded-elastomeric fasteners met allrequirements of the tie-wear tests as de-scribed in the BARTD Specifications.(t)

Spring-Clip Fastener. The initial torqtrein the anchor bolts connecting the fastenerplate to the concrete base was 2001b-ft.

Two million cycles of loading were ap-plied to the fastener. During this part ofthe test, lateral deflection was checked. Themaximum total lateral movement of therail head was 0.039 in. This value is wellwithin ~j ~ in. total movement implied bythe BARTD Specifications.(3) No visiblesigns of distress were observed during thisportion of the test.

The torque in the four anchor- bolts con-necting the baseplate to the concrete blockwas checked after 2 million cycles of load-ing. This check showed that tcn-que in thebolts had dropped an average of 20 lb-ftfrom the initial value of 200 lb-ft.

After 2 million cycles of Ioa,ding, inden-tations were found on the upper surface ofthe lower rail flange where the clips madecontact with the rail. The maxi mum depthof the dents was measured to be 0.01.2 in.

The fasteners were subjected to an addi-tional 11,500 cycles of loading according toAddenda 3 and 4 of the BARTD 5pecifica-tions.( ~) No undesirable movement wasobserved when repeated loads were appliedwith the bolts connecting the fasteners tothe concrete base on the gage side removed.

The spring-clip fastener met all require-ments of the tie-wear tests described in theBARTD Specifications.(3)

Second-Cast, and Wave-Action Test

The forged-clip fastener was subjected toa reversed load test intended to representthe “wave action” that occurs in tracks dueto wheel loading. A construction sequencewas also studied to determine tlhe problemsinvolved in casting a concrete levelingcourse under fasteners attached. to a rail.

Manufacture of Test Base. As shown inFig. 28 the base of the test specimen was a9 x 48 x 96-in. concrete slab representing aportion of the deck of an elevated struc-ture. The central trough, where the railstrip concrete was later cast, was formed by

30 Journal of The P(ZA Research and

15Y2° _ ,’jyz,’

STEEL CLAMP

HUB,., LINE.

STEEL BASE

“ “Z*::

LLB

+“ .SECTION A-A

(THIS SECTION IS TWICE TME SCALE OF SECTION 6-E ]

Fig. 28 — Details of Test

scraping out the fresh concrete to the de-sired level 1 in. below the surface of thebase slab. The surface of the trough wasfinished with a wood float, but was leftslightly rough as shown in Fig. 29. The slabwas cured and then stored for one month.After placing the additional reinforcement,an S-ft len~th of a 115-lb RF. rail with threefasteners attached was temporarily sup-ported as shown in Fig. 30. The rail stripconcrete was then cast beneath the rail.The concrete anchors were supported bythe fa:stencx whi lC the concrete was beinsplaced.

At [0 days from the date the concretewas placed, forms were removed to permitinspection of the finished specimen. Therail and fastener assembly was also re-moved to facilitate inspection of the con-crete surface under the polyethylene pads.Fig. 31 shows bot b the concrete surface andthe top surfaces c)f the polyethylene pads. Itcan be seen that mortar from the coucretehad penetrated into the space between thepolyethylene pads and the baseplates of thefasteners. These crescent-shaped pieces ofmortar were about 0.10 in. thick.

The mortar did not adhere to the poly-ethylene pads. Consequently, it could notbe expected to provide permanent loadtransfer between the fastener baseplateand the pad. Since this problem was the

Development Laboratories, September l?68

Specimen for Cyclic Loading.

result of a construction procedure thatcould easily be changed the specimen wasnot remade. Loose mortar was removed and

the space between the polyethylene padand the rail strip concrete was filled withan epoxy filler (Araldite No. 502 with sili-ca ffour) mixed to the consistency of petro-leum jelly. This filler served to hold theplastic pad in contact with the bascplau: ofthe fastener. The rail assembly was then setin place. Riser holes in the plastic pads al-lowed the excess material to be forced outas the assembly settled into place. The riser

Fig. 29 — Trough for Rail-Strip Concrete.

31

Fig. 30 — Rail Positioned.

holes were plugged when firm support wasreached at the bolts. Twenty-four hourslater the anchor bolts were removed,cleaned, repktced, and tightened to the de-sired torque of 200 Ib-ft. The clip boltswere tightened to a torque of 275 lb-ft.

Preparation for Cyclic Loading. Prior tothe application of the cyclic loads, it wasnecessary to determine by application ofstatic loads the distribution of forces to thethree fasteners. In preparation for suchstatic tests, the rail was instrumented andcalibrated for both vertical and horizontalloads. Two strain g-age bridges, each madeup of fOur electrical resistance strain gages,were attachec[ to the rail 10 in. to each sideof its midlength. On each side of mid-length, one bridge responded only to hori-zontal load, the other ordy to vertical.Horizontal and vertical bending tests forcalibration were made with a central load

applied to the bare rail. During the cali.bration, the rail was supported as a simplebeam at the two end fastener locations.The load measuring bridges provided anaccuracy of measurement of +7 lb for hori-zontal load and *Z6 lb for vertical load.

After calibration, the rail was placed inthe fastener assembly. The entire test speci-men was then placed in the test rig shownin Figs. 32 ztnd 33, and static loads were

applied. Distribution among th~e three fa~-teners was first determined jfor verticaldown and up loads with the assembly hori-zontal under the load frame. Next, distri-bution of lateral load was determined withthe specimen at an angle of 18.5 degreesfrom horizontal. The distribution of forceto the center fastener was found to be 83,67, and 88 percent for vertical-down, verti-

cal-up, and horizontal load, respectively.After completion of the cyclic portion ofthe test, distributions were rechecked, andno change was noted.

To obtain the desired loads for the cen-ter fastener, the assembly was set at an an-gle of 24 degrees from the horizontal. Fromthe geometry of loading at this angle, thecomponent acting in the plane of symmetryof the raiI was 91.3 percent of the appliedload, the lateral component 40.7 percent.The components of the force on the centerfastener acting in the rail symmetry planewere then 75.5 percent and 61.1 percent ofthe applied down and up load:j, respective-ly. The maximum lateral force on the cen-ter fastener was 35.8 percent of the applieddown load.

Cyclic-Load Test. A 50,000-lb capacityAmsler compression ram was used for thedown-load portion of the cyclic loads ap-plied to the rail assembly. The pulsator

32 Journal of The PC-4 Research and

used with this ram provided a sinusoidalclown-load at a rate of 500 cycles per min-ute. W,ith this ecluipment, the maximumand minimum dc>wnward loads could beadjusted to any desired magnitude. How-ever, for this test, an upward load was re-quired for the “minimum.” Since the Ams-ler rams are sing] e-acting, this load couldnot be applied by the same ram. Conse-quently, it was necessary to use overheadSpring%m shown in Figs. 32 and 33, to pro.vlde the up-load on the rail. The springforce was partially overcome at the ramminimum load and completely surpassedby the ram maximum load. Superpositionof these forces gave a resultant load to therail which varied sinusoidally.

The cyclic loading was carried out withthe ram. force varying from 22.2 kips to 2.0kips, and with a spring force of 3.6 kips.The resultant total load acting on the railin its plane of symmetry varied from 17.0kips down to 1.5 kips up. “f%e maximumlateral component. was 7.6 k.ips at the railcentroid. Ten mill[ion cycles of this loadingwere applied at t~he rate of 500 cycles perminute.

The rail-clip-bol[t and anchor-bolt torqueswere clhecked with a torque wrench atabout every one mlillion cycles. When a 10SSwas noted, the bo,lt was tightened back toits original preloald.

Test Results. No evidence of failure ordamage was noted in any part of the speci-men during the 10 million cycles of load-ing. Load–deflection curves obtained forthe center fastener before and after the cy-clic-load tests are shown in Fig. 34. Duringthe first 2 million cycles, the bolts requiredperiodic readjustment of torque. No loss oftorque was noted thereafter.

At the conclusion of the test, inspectionof the parts of the test specimen revealedthat the only par t visibly affected by theloading was the rubber liner at the centerfastener. Scuffing and erosion were observedon the surfaces of this liner. Both halves ofthe liner showed ]minor damage where therubber was in contact with the steel.

An indentation in the shape of the edgeof the steel clip was visible in the rubberliners, as shown in Fig. 35. Cracking of therubber occurred along this indentation inone of the liner halves. The crack was lo-cated on the outside surface of the liner atthe lower flange of the rail. At this loca-

tion, there is a gap between the steel clipand the steel baseplate. The crack in therubber followed the outline of the loweredge of the clip and turned upward alongits sides for l/a in. The depth of the crackvaried from about 0.09 in. at the outer cor-ners of the trace to a maximum of 0.13 in.at 0.5 in. from the corner. It decreased indepth to a slight indentation over the cen-tral 1 in. of the 3.8-in.-wide clip.

NO cracks or other signs of distress werevisible in the steel, polyethylene, or con-crete.

(a) East Fastener

(b] Center Fastener

(c) West Fastener

Fig. 31 — Inspection of Rail-Strip Concrete

Placement.


,m,

‘TRAILCONI

\F

&

1

-%., ~ ANGLI.. . =..,~

a4s&

)3 1

AOJU$

RA IUS#

%4&F OM RAILCENTRCIID

L

STRAIN GAGEDSECTION FORDETERMINATIoN OFI.OAD DISTRIBUTION

“0) !=====E——

—f 4“SQ. TUBE

.- LOAD FRAME

25-TON RAM

TESTSPECIMEN SHOWN::~i+&fl~L FOR

L .–_

-%

~ RAIL

,BLE I BASE SLAB

— -XT.—TEST I:LOOR A— SECTION A-A

Fig. 32 -- Details of Test Setup for (lyc!ic Loading.

CO1’4CLUDll’dG COMMENTS

Some fasteners for attaching rails to con-crete crossties and to concrete bridge decksand tunnels provide adequate electricalinsulation and have good mechanicalproperties. Major conclusions and recOm-

F!g. 33 — General View of Cyclic-Load Test Setup.

34

mendatiom have been disctmed -in the“Highlights” section at the beginning ofthis report.

ACKNOWLEDGMENT

This investigation was conducted in theStructural Research Laboratory, PortlandCement Association Research and Develop-ment Division under the direction of D-r.Eivind FIognestad, Director of EngineeringResearch, and Dr. W. G. Corley, Managerof the Structural Research Section. Prepa-ration of the section of this report concern-ing fasteners for bridges and tunnels has

, .— —=–—1

i’-!==!0 001 002 003

RAIL DEFLECTlON 07 CENTER FASTE NER (8. 1

Fig. 34 — Rail Deflection.

Journal of The P(:A I?esearch and

REFERENCES

Fig. 35— Rubber Itiner from CXnter FastenerAfter Tes#.

been financed in part through a mass trans..portation grant from the Department ofHousing and Urban Development underthe provisions of Section 6, public Law 88-365, 88th Congress, as amended. This por-tion of the work was done to assist in devel-opment of the track system for the SanFrancisco Ray Area Rapid Transit District.It was carried out under contract with Par-sons–13rinckerhoff-.’TudoBechtel,l, genera [engineering corrstdtants to SFBARTD.The authors wish to thank Messrs. B. “W.Fnllhar-t, QJ. A. Krmvits, R. K. Richter,lV. G. Vix, B. J. Doepp, and S. Zintel,laboratory technicians, and R. G. Hoffman,photographer, for carrying cmt and record-ing the tests.

1. “’IG&o-B&O Wan Concrete Tie Tests,” ModemZJailr,d., 12, No. 12, 91-92 (1966).

2. “AREA Proposed Specificationsfor Desisn, ~a-terials,Constructionand Inspectionof PrestressedConcrete Ties.” Proposal submitted to ,%nericanRailway Engineering Association, private colu-

munication from Emerson J. Ruble, of American

Association of Railroads, Chicago, Illinois. (Re-vised Mav 1. 1968).

3. P’arsons-.Eri~ckerh’o ff-Tudor-f3echtel, General En-

gineering Consultants for the San Francisco BayArea Rapid Transit District, “PreIimirrwy Tech-n ical Specifications for Rail Fasteners,” No.2Z4489 (1967).

4. Godfrey, K. A., Jr., “Rapid Transit Renaissance,”Civil Engineering, 36, No. 12, 28-33 (1966).

5. Monfore, G, E., “The Electrical Resist ivity ofConcrete,’” Journal of the PCA Research, and DFJ-

rxlofime?rt Laboratories, Ml, No. 2, 35-48 (May

1968); PCA Research Defiartmen t BuHe tin 224.

6. ASTM Designation: D 1248-6537, “Tentati w Spec-

ifications for E’olyedtylene Molding and ExtrusionMaterials,” American Society for Testing andMaterials, Philadelphia, Pennsylvania.

7. ASTM Designation: D 789-66, .’Standard Spec-ifications for Nylon Injection Molding and Ex-trusion Materials.” As in Reference &

8. Hogncstad, Eivind, Hanson, N. W., Kriz, Ladi-slav B., and Kurvits, Otto A., “Facilities andTest Methods of the PCA Structural Labora-tory,” papers under variom titles in Journal ofthe PCA Research and Development Labora-

tories, 1, No. 1, 12-20, 40-44 Uanuary 1959); 1,No. 2, 30-37 (May 1959); L No. 3, 35-41 (Sep-tember 1959); reprinted joindy as PCA Ikweiop-

ment Department Bulletin D33.

9. Hanson, N. W., Hsu, T. T. C., Kurvits, O. A.,and Mattock, A H., “Facilities and Test Meth-ods of PCA Structural Laboratory— lmprove-nrents 1960-65,” papers under various titles imJournal of the WA Research and Dtwelopment

Laboratories, 3, No. 2, 27-31 (May 1961); 7,

“No. 1. 2-9 (January 1965); 7, No. 2, 24-$8 (May1965); reprinted jointly as PCA DevelopmentDepartment Bulletin D91.

PCA.R&L9.Ser.1381-2

Development Laboratories, September 1968

Bulle+ins F%b!ishecl by =the

Ekwelopment Department

I?esearch and Development l.aboratcwies

of the

Pcwfland Cemen+ }%socia+ion

DIOO—’’Index of Development Department Bulletins D1-D99. Annotated List with Author

and Subject Index. ”

Published by Portkmd Cement Association, Research and Development Laboratories,Skokie, [Ilinois (1967).

l)lO1-(JRotational Capacity of Hinging Regions in Reinforced Concrete Beams, ” by ALAN

“H. IWATTOclK.

Reprinted from FLEXURAL MECEiANXC$ OF REINFORCED CONCRETE, Proceedings of the, Intev-nationa~ ~YwIPosiuwL, Miami, Fla. (Notwmbm 1964) pages 143-181, joint sponsorship.Copyrighted 1965 by American Society of Civil Engineers.

D102—’’Tests of Partially Prestressed Concrete Girders,” by DONALD D. MACXTRA and EWIND

HOGNESTAD.

Reprinted from the Journal of the Structural Division, Proceedings of the AmericanSociety ,, f Civil Engineers, Proc. Papev 4685, 92, ST 1, 327-350 (February 1966).

1)103—’’Influence of Size and Shape of Member on the Shrinkage and Creep of Concrete,”

by TORBEN C. HANSEN and ALAN H. MATTOCK.

Reprinted from Journal of the Ametican Concrete Institute (February 1966); Proceed-ings 63, 267-290 (1966).

D104--’’Cain-Placeace Concrete Residences With Insulated Walls, ” by HARRY L. SCOGGIN.

R.eprinte d from Journal of the PCA Research and Development Laboratories, S, No. 2,2’1-29 (May 1966).

D105—’’Tensile Testing of Concrete Block and Wall Elements,” by RICHARD O. HEDSTROM.

Reprinted from .lormm’d of the PCA Research and Development Laboratories, 8, No. 2,42-52 (May 1966).

D106—’’High Strength Bars as Concrete Reinforcement, Part 8. Similitude in Flexural

Cracking of T-Beam Flanges,” by PAUL H. KA.AEL

Reprinted from Journal of the PCA Research and Development Laboratories, 8, No. 2,2..12 (May 1966).

D107—’’Seismic Resistance of Reinforced Concrete—A LabOrafOrY Test Rig,” by NoRMAN

W. HANSON and HAROLD W. CONNER.

Reprinted from Journal of the PCL4 Research and Development Laboratories, S, No. 3,2-9 (September 1966).

D108—’’Rotational Capacity of Reinforced Concrete Beams, ” by W. GENE CORLEY.

Reprinted from Journal of the S%wctural Division, Proceedings of the American SO-cietu of CiuiI Engineem, Proc. Paper 4939, 92, ST5, 121-146 (October 1966).

D109—’’Laboratory Studies of the Skid Resistance of concrete. ” by G. G. BALM1OR andB. E. COLIIEY.

Reprinted from ASTM Jormnat of Materiak 1, No. 3, 536-559 (September 1966).

Dl10—’’Connections in Precast Concrete Structures—Column Base Plates,” by R. W.

LAFRAUGH and D. D. MAGURA.

Reprintc!d from Journal of the Prestressed Concrete Institute, 11, No. 6, 18-39 (De-cember 1966).

Dill—’’Laboratory Study of Shotcrete.” by ALRERT LITvIN and JOsEpH J. SHIDELER.Reprintc!d from SY??zPostum on Shotcreting, American Concrete Institute, Paper No.13 in Publication SP-14, 165-184(1966).

D112—’6Tests on Soil-Cement and Cement-Modified Bases in Minnesota, ” by Tom.rORN J.LARSEN.

Reprinted from Journal of the PCA Research and Development Laboratories, 9, No. 1,25-47 (January 1967).

D 113—’’Structural Model Testing—Reinf orced and Prestressed Mortar Beams, ” by DON-

ALD D. MAGURA.

Reprinted from Journal of the PCA Research and Development Laboratories, 9, No. 1,2-24 (January 1967).

Dl14--’’General Relation of Heat Flow Factors to the Unit Weight of Concrete,” byHAROLD W. BP.EWER.

Reprinted from Jour?za~ of tfae PCA ,Research and DevetoD?ne?st Laboratories, 9, No. 1,46-60 (January 1967 ).

D,l15-.’’Sand Replacement in Structural Lightweight Concrete—Sintering Grate Aggre-

gates,’> by DON.ILD W. PFEIFER and J. A. HANSON.

Reprinted from JoumsaG of the American Concrete Institute (March, 1967): Proceedings64, 121-127 (1967) .

D:[16—’’Fatigue Tests of Reinforcing Bars–-Tack Welding of Stirrups,” by KENNETH T.

BURTON and EIVIND HOCNESTA~.R(?printed from Journal of the Amertcan Concrete Institute (May, 1967); proceedings64, 244-252(1967)

Dl17—.’’Connections in Precast Concrete Structures—Effects of Restrained Creep andShrinkage,” by K. T. BURTON, W. G. CORLEY, and E. HOGNESTAD.

~:6~ted from Journal of the Prestressed Conc~ete Institute, 12, No. 2, 18-37 (April,

D 118--’’Cain..in-Place Concrete Residences with Insulated Walls—Influence of Shear Con-nectors on Flexural Resistance,” by HARRY L. SCOGGIN and DONALD W. PIFEIFEF..

Reprinted from Jouma[ of the PCA Reseamh and Development Laboratories, 9, No. 2,Z-7 (May 1967).

D’t 19—’’Fatigue of Soil-Cement,’> by T. J. LARSEN and P. J. lJUSSBAUNZ

Reprinted from Journal of the PCA Research and Development Laboratories, 9, No 2,37-59 (May 1967).

D120-’’Sand Replacement in Structural Lightweight Concrete—Splitting Tensile Strength,”by D’ONALD W. PFEIFER.

Reprinted from Journal of the American Cmwrete Institute (July 1967); P~oceedings 64,384-392 (1967)

D121—’’Seisrnic Resistance of Reinforced Concrete Beam-Column Joints,” by F70RMAN

W. HANSON and HAROLD W. CONNER.

Reprinted from Journal of the Structural Division, Proceedings of the American Societyof Civil Engineers, PTOC. Paper 55S7, 93, ST5, 533-560 (October 1967).

D122–-’’Precast Rigid Frame Buildings-–Test of Scarf Connections,” by PAUL H. KAAR andHAROLLI W. CONNER.

Reprinted from Joumat of the PCA Research and Deueiop?nent Laborato?les, S, No. 3,34-42 (September 1967).

D123—’’Prec&st Rigid F~ame Buildings—Component Tests,” by HAROLD W. CONNER and

PAUL H. KAAR.

Reprinted from Journal of the PCA Research and Development Laboratoldes, 9, No. 3,43-55 (September 1967 ).

D12&’’Aggregate Interlock at Joints in Concrete Pavements,” by B. E. COLLEY and H. A.HUMPHREY.

Reprinted from Highway Research :RECORD, Number 189, 1-18 (1967).

D125—’’Cement Treated Subbases for Concrete Pavements,” by L. D. CHILDS.Reprinted from Highway Research RECORD, Number 189, 19-43 ( 1967).

‘D126—’’Sand Replacement in Structural Lightweight Concrete—Freezing and ThawingTests,:’ by DONALD W. PFEIFEB.

Reprinted from Journal of the American Concrete Institute (November 1967) ; Proceed-ings 64, 735-744 (1967 ).

D127—’’Ultimate Torque of Reinforced Rectangular Beams,” by THOMAS T. C. Hsu.Reprinted from Journal of the Structural Division, Proceedings of the .American So-ciety of Civit Engineers, Proc. Paper 5814, 94, ST2, 465-S10 (February 196fl ).

D128—’’Sand Replacement in Structural Lightweight Concrete-Creep and ShrinkageStudies,” by DONALD W. PFEIFER.

Reprinted from Journal of the American Concrete Institute (February 1968’1; Pro.ceedings, 65> 131-140 (1968).

D129—’’Shear and Moment Transfer Between Concrete Slabs and Columns,” by NORMAN

W. HANSON and JOHN M. HANSON.

Reprinted from Journal of the PCA Research and Development Laboratories, 10, NQ.1, 2-16 (January 1868)

D130—’’Trends in Consumer Demands for New Grades of Reinforcing Steel,” by EIVIND

HOCNESTAD.

Reprinted from P~oceedtnm, Fall Business Meeting, Concrete Reinforcing SteelInstitute, pages 22-32 (1967).

D131—’’Influence of Mortar and Block Properties on Shrinkage Cracking of MasonryWalls,” by RICHARD O. HEDSTROM, ALBERT LITVIN, and J. A. HANSON.

Reprinted from Journal of the PC!A Research and Develotnnent Laboratories, 10,No. 1, 34-51 (January 1968).

D132—’’Toward a Generalized Treatment of Delayed Elasticity in Concrete:’ by DOUGLAS

iVICHENRY.

Reprinted from PUBLICATIONS, International Association for Bridge and StructuralEngineering (Zurich ), Vol 26, pages 269-283 ( 1968),

D133—” Torsion of Structural Concrete—A Summary of Pure Torsion,” by THOMAS T. C.Hsu.

Reprinted from TORSION OF STRUCTURALCONCRETE,American Concrete Institute,Paper SP 18-6in Publication SP-18, 165.178(1968).

D134--’’Torsion of Structural Concrete—Plain Concrete Rectangular Sections,” by THOMAST. C. HSU.

Reprinted from TORSION OF STRUCTURAL CONCRETE, American Concrete Institute,SP 1S-!3 in Publication 5P-IS, 203-236 (1968).

1.3135-’’Torsion of Structural Concrete—Behavior of Reinforced Concrete RectangularMembers,” by THOMAS T. C. Hsu.

Reprinted from TORSION OF STRUCTURAL CONGiETE, American Concrete Institute,Paper SP 18-10 in Publication SP-18, 261.306(1968).

D136—’Trecast Rigid Frame Buildings—Summary of a Laboratory Investigation,” byPAUL H. KAAR and HAROLDW. CONNER

Rerminted from J0UT7ta[ of the PCA Research and Development Laboratories, 10, No.2, 25-34 (May 1968).

D137—’’Clear Coatings for Exposed Architectural Concrete;’ by ALBERT LXTVIN.Reprinted from Journal of the PCA Reseamh and Development Labo~atories, 10, No.2, 49-57(May 1968).

D133--’’’Torsion of Structural Concrete—Interaction Surface for Combined Torsion, Shear,and 13endin,g in Beams Without Stirrups,” by THOMAS T. C. HSU.

Reprinted from Journal of the American ConcTete Institute (January 1968); PTo-ceedin$?s, 65, S1=0 (19S8).

D133-’’Influence of Aggregate Properties cm Effectiveness of Interlock Joints in ConcretePavements,” by W. J. NOWLEN.

Reprinted from Journal of the PCA Research and Development Laboratories, 10, No.2, 2-6 (May 1968).

D140—’’Torsion of Structural Concrete—Uniformly Prestressed Rectangular Mt!mbersWithout Web Reinforcement,” by T~O~As T. C. Hsu.

Reprinted from Journal of the Prestressed Concrete Institute, 13, No. 2, 3444 (April1968).

D141—’’EffectB of Curing and Drying Environment on Splitting Tensile Strength of Con-crete;’ by J. A. HANSON.

F&m&ted from American concrete Institute (JuIY 1968): Proceedings, 65, 53~543

D142—’’Resealrch on Thickness Design for Soil-Cement Pavements,” by T. J. LAMEN,P. J. NUSSBAUM, and B. E. COLLEY.

Published by Portland Cement .%sociation, Research and Development laboratories,Skokie, Illinois (1969).

D143—’’Fatigue Tests c,f F’restressed Concrete Pavements,” by A. P. CHKISTENS~N andB. E. COLLEY.

Reprinted from Highway Research Record, Number 239, 175-196 ( 1968).

D14k’’Shearhead Reinforcement for Slabs,” by W. GENE CORLEY and NEIL M. HAWKINS.

Reprinted from American Conrmte Institute (October 1968); Proceedings, 65,811-824 (1968) .

D145—’’Fatigue Tests of Reinforcing Ears—Effect of Deformation Pattern, ” by .J. M.HANSON, K. T. BURTON and E. HOGNESTAD.

Reprinted :from Journal of the PCA Resea?’ch and Development Laboratories, 10,No. 3, 2-13 ( September 1968).

D146—”An Investigation of Rail-to-Concrete Fasteners,” by T. T. C!. Hsu and N. W.HANsON.

Reprinted from Journal of the PCA Research and Development Laboratories, 10,NCI.3, 14-35(September 1968).

Printed in U.S.A.

i.20 l-! An lCl VeSTl CJdTl Q17 OT

i Rail-to-Concrete Fasteners”I

I_I

KEY WORDS: anchors; concrete railroad tics; electrical insulation; electrical resistance;

:longitudinal slip; pullout tests; rail fasteners: railroad ties; repeated loads; testing

~SYNOPSIS: Prestressed concrete railroad ties are being incrcasin~ly used. This investi-

1gation deals with the rail-Lo-concrete fasteners for concrete tins, bridge decks, anti

itunnel linings. For spring-clip fastcmcrs in concrete ties, three methods of electrical

Iinsu Iation were studied. These fasteners were subjected to tic-wear tests, longitucfinal-

1slip tests and electrical-resistance tests. The anchors used were also subjected to pullouttests. For fasteners in bridges and tunnels, three different fasteners were tested under

I repeated loading. In addition, the “second-cast” method of construction was studied.

!

I

IREFERENCE: H[su, T. T. ~., and Hanson, ~’f~rmal~ w., ]Ournaz Of the ~’CA Research

Iand DerMofnnerrt Laboratories (Portland Cement Association, U.S.A.), Vol. 10, No. 3,September 196$3, pp. 14-35; PCA Development De@rrtment Bulletin D146.

1II— Ii 138 I -1 “An Investigation ofI RaiI-to-Concre+e Fasteners”1 II: KEY WORDS: anchors; concrete railroad ties; electrical insulation; clcctl-ical resistance;

1longitudinal slip; pullout tests; rail fasteners; railroad ties; rcpeatetf loans; testing

I

i SY~lOFSIS: E’rcyressecf coucrctc railroad tics are being increasingly used. This investi-

1 gatlon deals with the rail-to-concrete fasteners for concrete ties, bridge decks, and

I tunnel linings. For spring-clip fasteners in concrete ties, three methods of electricalinsulation were studied. These fasteners were subjected to tie-wear tests, longitudinal-

!slip tests amf electrical-resistance tests. The anchors used were also subjected to pullouttests. For fasteners in bridq-es and tunnels, three different fasteners were tested uncfcr

Irepeated loading. In addltlon, the “second-cast” method of construction was studicci.

III

REFERENCE: HSCI, T. T. C., and Hanson, Norman W., .louvnal of the PCA Re.ceavch

Iand Deuelopmmzt La.borutories (Portland Cement Association, U.S.A.), V,ol. 10, No. 3,

ISeptember 1968, pp. 14-35; PCA Deuelopmerat Department Bullelin L)146.

Il— 1

1381-1 “An investigation of

Rail-to-Concrete Fasteners” LKEY WORDS: anchors; concrete railroad ties; electrical insulatiOw electrical resistance:longitudinal slip; pullout tests; rail fasteners; railrcnrci ties; repeated loads; testing

SYNOPSIS: Prestrcssccf concrete railroad ties are beinS increasingly used. This investi-gation deals with the rail-to-concrete fasteners for concrete tics, brid~e decks, andtunnel linings. For spring-clip fasteners in concrete ties, three methods of electricalinsulation were studieci. These fasteners were subjected to tie-wear tests, longitudinal-

slip tests and electrical-resistance tests. The anchors used were also subjccfed to pullout

tests. For fasteners in briflges and tunnels, three different fasteners were tested underrepeated loading. In addlt]on, the “second-cast” method of construction was studied.

REFERENCE: HSU, T. T. C., mcf ~~a~scrn, N’orman W., Journal of the 1’CA Rewarc/raria! Development Laboratories (Portland Cement Association, U.S.A.), Vol. 10, No. 3,September 1968, pp. 14-35; PCA Development Department Bulletin D146.

i an investigation of rail- to - concrete fasteners · fig. i — insulating systems for rails...

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