BELL SYSTEM PRACTICESOutside Plant EngineeringAntenna Supporting Structures

E GUYED TOWERS

ERECTION

1. GENERAL . .

2. PRE-ERECTION

3. INSTALLATION. . . . .

CONTENTS PAGE

. . . . . . . . .

CONSIDERATIONS . . .

OF BASEPLATE ASSEMBLY. . . . . . . . .

4. TEMPORARY WARNING LIGHTS . . .

5. ERECTION CONSIDERATIONS . . . .

6. GUY TENSIONS . . . . . . . .

1

1

2

3

3

10

1. GENERAL

1.01 This section outlines the general considerationsinvolved in erecting E Guyed Towers, and

includes recommended procedures and precautions.

1.02 Erection drawings are normally furnishedwith the tower, and provide information

necessary for the field assembly of the tower,including the location and orientation of everypiece and subassembly. All steel (except nuts,bolts, and washers) is identified by stencils, stamps,or metal tags which correspond to the markingsshown on the erection drawings. The identifyingmark of leg members is located on the outer facenear the lower end. These drawings also showthe number and length of bolts, nuts, and washersrequired to join the members. A more thanadequate supply of bolts, nuts, and washers isfurnished with the tower, but care must be exercisedto ensure that the proper size of each is used foreach joint, or a shortage of some sizes may develop.

SECTION 760-925-330,

Issue 1, August 1967

AT&TCo Standard

2. PRE-ERECTION CONSIDERATIONS

2.o1 Tower erection should not be started untilall required permits have been obtained,

as outlined in Section AG25.320.

2.o2 The permit issued by the Federal CommunicationsCommission (FCC) to construct and operate

a radio system usually indicates whether or notlighting and painting to improve visibility arerequired. Where only receivers are to be installedand it has been determined that FCC permissionis not required, the Federal Aviation Agency (FAA)will determine the necessity for lighting or paintingto improve visibility. If lighting is required,arrangements must be made to assure the availabilityof electric power at the site, and the lightingfacilities must be ordered and on hand at thetower site. Note that the standard lighting kitprovides only the material which goes on the tower.Conduit and wire from the base of the tower tothe lighting control panel in the building shouldbe ordered locally. Methods of lighting and paintingtowers are described in Sections AG25.230 andAG25.300. Information on temporary warning lightsis contained in Part 4 of this section.

2.03 Section AG25.320 provides information onfoundations and anchors for E Guyed Towers.

Steel erection should not be started until the resultsof concrete compression tests are known to besatisfactory. (See Section AG25. 130 for a discussionof concrete. )

2.04 The grounding system at the anchors shouldbe completed and the grounding connections

at the foundation should be readily accessible.Installation of the grounding system is describedin Section AG25.320.

@ American Telephone and T;legraph Company, 1967

Printed in U.S.A. Page 1

SECTION 760-925-330

2.05 All equipment to be installed on the towershould be available when required, and its

mounting location on the tower should be specifiedto the contractor in’ order that hoisting equipmentmay be positioned to avoid conflict.

2.06 If aerial electric power facilities are in alocation that may present a hazard to or

interfere with temporary guys, hoisting equipment,tag lines, etc, arrangements should be made tohave the power company relocate, de-energize, orinsulate its facilities.

2.07 Foundations and anchors should be carefullychecked to ensure that they are located

correctly and are of the right size. This shouldinclude checking the azimuths of the anchors, whichin turn fix the transmission blind sectors referredto in Section AG25. 310. Details of layout arecovered in Section AG25.320.

2.08 It may be desirable to install a talking circuiton the tower to facilitate adjustment of

antennas and reflectors during system lineup.Information on this subject is contained in SectionAG25.230. A physical circuit can be avoided byuse of the walkie-talkie radio, if this equipment isavailable. This equipment may also prove of valuein the erection of the tower itself.

3. INSTALLATION OF BASEPLATE ASSEMBLY

3.01 Both the foundation surface and the baseplateshould be cleaned of mud, grime, and other

foreign matter. The baseplate is then installed(Fig. 1) by placing it on four tapered steel wedgeslocated about midway between the anchor bolts.The plate is leveled by adjusting thethe baseplate is symmetrical aboutmay be installed without regard toon the pier.

wedges. Sincethe center, itits orientation

,.“

//GROUT APPROXIMATELY

STEEL WEDGE

TOP OF CONCRETE FOUNDATION

Fig. 1—Installation of Baseplate Assembly

Page 2

1ss 1, SECTION 760-925-330

3.02 After the baseplate has been leveled, theanchor bolt nuts should be tightened. The

wedges should provide a clearance of 3/4 to 1-1/4inches between the baseplate and pier to allowfor grout. The baseplate may be installed at anytime after the results of the compression tests onthe concrete are known to be satisfactory.

3.o3 The grout should consist of one part portlandcement (Type I or III ) to two parts sand

(by volume). Portland cement is described inSection AG25. 130. Clean sand from a reliablesupplier should be used in the grout. The watershould be clean and fit for drinking.

3.o4 The consistency of the grout must be verystiff. The sand and cement should be

thoroughly mixed in a dry condition and then watershould be added sparingly so that the mixtureretains a granular appearance. Grout of the properconsistency will form a lump when squeezed inthe hand, and the lump will crumble freely whendisturbed.

3.o5 Grout should be forced under the baseplatefrom all sides, and should completely fill all

voids. The wedges should then be removed, andthe void left by removing the wedges should befilled immediately with additional grout. The groutshould be beveled as illustrated in Fig. 1.

4. TEMPORARY WARNING LIGHTS

4.o1 The rules of the FCC and FAA require thattemporary warning lights be placed on any

tower which is required to have permanent airobstruction warning lights. The number of sets( or levels) of temporary lights required will bethe same as the number of levels of permanentlighting. Where two or three levels of permanentlights are required, only one temporary set of lightsis required (at the top) until the level of the firstpermanent lights is exceeded. Temporary lightsshould then be installed at approximately the levelof permanent lights and, in addition, a set oftemporary lights is always required at the uppermostpoint of the structure. Even on towers requiringonly one level of permanent lighting, a set oftemporary lights is required at the top of the

structure, and this applies even though only onesection of the tower may have been erected bysunset.

4.02 Temporary lights are to burn steadily fromsunset to sunrise. Top lights are to consist

of two 100-, 107-, or 116-watt lamps (A21/TS)enclosed in aviation red obstruction light globes.Two similar lights are required at each level wherepermanent lights are to be installed. (Permanentlights may be used in lieu of temporary lights. )All side lights are to be positioned so at least oneof the two lights at each level will be visible fromany angle of approach. Many contractors havetemporary warning lights for use during erection,but it is advisable to notify them if temporarylighting will be required, and whether it will beone-, two-, or three-level.

5. ERECTION CONSIDERATIONS

5.o1 Erection of steel towers is usually perforr,edby contractors rather than by Telephone

Company personnel. It should be noted that thecontractor is responsible for the job and for theconstruction methods he chooses to use, and ispresumably the best judge of the condition of hisequipment and the loads which it can handle.However, the Telephone Company representativeshould assure normal safeguards and require thecontractor to correct any obviously dangerous itemssuch as frayed winch lines and ropes.

5.02 The general appearance of the base of thetower is shown in Fig. 2. Note the use of

12-inch channels in the base, and 8-inch channelsfor internal bracing. Four bolts connect the towerbaseplate to the flange of each 12-inch channel. Awasher is placed under the head of each bolt, inaddition to the one used under the nut (Fig. 3).

5.o3 Most structural members of the tower areformed of angles. Legs are 60-degree angles;

lacing and horizontal bracing are all 90-degreeangles. Note that the legs are double-laced with1-1/2 by 1-1/2 by l/8-inch angies, ie, cross-braced,except for the top section. This is a tension-compressionsystem and to get the maximum strength out ofthese small angles, they are bolted together at

Page 3

\

SECTION 760-925-~

E

LEG

12 IN. ANGLE

CHANNELS

COMPLETE BASE OF TOWER

8 IN. CHANNEL

PLATE

WER BASE

ATE

INTERNAL BRACING OF TOWER BASE

Fig. 2—Base of Tower

the point where they cross. On a given face,since one set of lacing angles is bolted to the insideof the legs and the other is bolted to the outside,angles which cross each other are separated bythe thickness of the leg members. As shown inFig. 4, a spacer washer must be installed to avoidthe bending of these angles which would result ifthey were bolted together without the spacer inplace. Double washers are required at one locationin the top section as discussed in 5.22.

s.04 It is general practice for contractors toassemble the tower sections on the ground,

with the associated splice plates attached looselyat the top of each leg. The lower diagonals areusually left loose to facilitate lining up holes whenthe section is put in place. The sections shouldbe inspected for such items as correct assembly,spacer washers, tightness of bolts, etc. All boltsshould be equipped with a plain washer, hex nut,and PALNUT.

FliEx tiEAO BOLT

BEVELED SURFACE

FLAT SURFACE

‘ExHEAoNu”@9‘ALN”T-Q9

Fig. 3—Use of Washer

5.05 Contractors will vary in the exact mannerin which they assemble the tower. Usually

the bottom section, and sometimes the two bottomsections, are bolted together on the ground andlifted onto the baseplate. Because of the ball-and-socket type of connection to the base pier, it isnecessary to use temporary guys to prevent thetower from overturning. Selection of the size andtype of temporary guys is the responsibility ofthe erection contractor. Temporary guys are tobe moved up with the tower so there is nevermore than one section (20 feet) extending abovethe levelintendedused for

of the temporary guys. Gu@-strandfor permanent gugs should not be

temporary gugs.

Page 4

1ss 1,SECTION 740-925-330

Q--.=-,,.,

LACINGANGLES

‘EXHEAD NUT+

“’’”’-69Fig. 4—Use of Space Washers

s.06 As soon as the first section (or sections) isin place and stabilized with temporary guys,

the grounding connections should be established.Each of the three 12-inch channels in the base ofthe tower has two 9/16-inch holes for a l/2-inchmachine bolt. Only one hole in two of the threefaces is used. The ground wire is secured undera grooved washer which is held in place by thel/2-inch machine bolt. Since the wire is tinnedcopper and the baseplate is galvanized, the presenceof water in the joint will cause galvanic actionbetween the dissimilar metals. The bolt shouldbe drawn up tightly and painted with hot pitch orother waterproofing material in order to preventthis galvanic action.

s.07 Permanent guys should be installed at theirappropriate level and correct tension as soon

as the tower reaches the height at which they arerequired. The structure should be made plumbbefore adding any more sections. Guy strand is

furnished in quantities sufficient to make up allguys with each anchor on a minus 6-degree(ground) slope, ie, a drop of about 10-1/2 feet perhundred feet.

5.08 The E Guyed Tower uses four differentsizes of guy strand as follows:

DIAMETER WEIGHT/FOOT ULTIMATE STRENGTH(INCHES) (LBS) (LBS)

1/2 .504 26,7009/16 .637 33,7005/8 .796 40,2003/4 1.155 58,300

The 80-, and 100-foot towers employ only one sizeof guy strand (9/16 inch); all other heights usetwo sizes of strand. Fig. 5 and 6 show the sizeand location of guys for all sizes of towers.Information on guy tensions is contained in Part 6of this section.

5.o9 A typical setup for erecting guyed towersis shown in Fig. 7. The gin pole is mounted

on one face of the tower and is fastened at twopoints The use of a wooden gin pole for erectingtowers is not recommended. The bottom of thegin pole is usually hung by two short lengths ofcable, shackled to each leg (Fig. 7A). The lowercables support the dead load of the gin pole plusthe loads imposed by hoisting. The upper set ofshackles (Fig. 7B) serves to support the gin polein a vertical position. Normally, the lengths ofboth sets of shackling cables are calculated so thatthe pole will not deviate from a vertical plane bymore than 10 degrees. This restricts the bendingmoment imposed on the tower and the gin pole.

5.10 Usually a gin pole will extend about 2 or 3feet above the top of the hoisted section.

This is necessary in order to provide headroomwhen a section is being set in place. The top ofthe gin pole is equipped with a pivoted head.When a section is being hoisted, the top of thegin pole will lean out to the limit of its top shackles.When the section reaches the upper block, hoistingis halted and the section is pivoted (Fig. 7, Sec. A-A)around the pole. With this transfer of weight,the top of the pole will kick-in, and the bottomwill kick-out. This action will put the center ofthe hoisted section near the center of the tower,and it can be lowered into place and bolted. It isrecommended that all bolts be installed and tightenedbefore progressing.

Page 5

SECTION 760-935-330

NOTE:

ALL TOP SECTIONS ARE IO EN TICALLEGs ARE 4X4X 5/161N.

5/8 INGUYS

9/16 IN.GUYS

65

Y “ ““

SIZE

OF LEG 3ANGLE y

\:

x

~

L .

9/16 INGUYS

2*>xN.

Tmxw.—

80 I00

N.

‘Tm

I20

Y’

40

\1/2 IN.

GUYS

5/8 IN.GUYS r

I 40 160

T’

$(1/2 INGUYS

4

80

180

‘!l/2”lN.GUYS

Fig. 5—1 80-Foot and Smaller Towers

Page 4

5/8 IN.GUYS

h

r

z—*>xN\7mxN\

Tm

I

1

/

SIZE

OF LEGANGLE +

\-

—*.

xexv

L,

200

NOTE:

ALL TOP SECTIONS ARE IDENTICAL

LEGS ARE 4 X 4 X 5/161N.

r

3/4 IN

GUYS

\Y

185

T

T

\

9/16 INGUYS /

220

205

T

120

\

\9/16 IN

GUYS

;0

\

\

1/16 IN,GUYS

: 73/4 IN,GUYS

3/4 IN.GUYS

r

225 g

*

7

>

xN\7m

2

:

xN>

ILx

I 40

:

h ‘f9/161N,GUYS

t-

/— \60

2

: r9/16 IN,

x GUYS*x*

L—_

240

xN>

!.! t

—

/ –

/ —

260

3/4 INGUYS

245

\

160

\

\9/16 IN

GUYS

Y

9/161N.GUYS

I

1ss 1,

3/4 INGUYS

\

265

160

‘\9/16 IN

GUYS

80

‘ \

9/161NGUYS

280

SECTION 760-925-330

285

T : ‘

~

*>

xN\

710xN>

1

y

L -

/ —180

‘19/16 INGUYS

I

I

z’—a<‘ax*x*

I

/—80

~‘ \

9/161N

GUYS

IL_

300

Fig. 6—200- to 300-Foot Towers

Page 7

SECTION 760-925-3~

SECTION A-A

Fig. 7—Typical Gin Pole Setup for Hoisting Tower Sections

s.1 I The gin pole is then raised to the nexthighest position, and the next section installed.

Normally, antennas or reflectors are hoisted onlyafter the tower is completely erected, all permanentguys have been installed at their proper tension,and the tower plumbed.

5.12 The gin pole method, when properly used,is capable of hoisting any single assembled

tower section, System Standard antenna or reflector(or comparable weights) without exceeding thedesign criteria of the tower. There are othersatisfactory construction methods used, such as

boom cranes, which are used quitecontractors erect supplementaryon the site for use in hoisting tower sections andequipment items.

frequently. Someportable towers

5.13 The ends of the guys are made up withpre-formed guy grips (Fig. 8), which are in

turn connected to the tower and to their respectiveturnbuckles. Care should be taken to install thesegrips properly so that the full strength of theconnection is developed. If it is necessary toremove the grip from the strand, it should bediscarded and not re-used.

Page 8

1ss 1, SECTION 760-925-330

PRE-FORMEO GUY GRIP

HEX JAM NUT

TURN8UCKLE

3/8 IN.\

TOWER BOLTS <

NuMBER OF UNUSECHOLES IN SPLICEPLATE VARIES WITHSIZE OF LEG—

Fig. 8—Lower End of GuySTANDARDSPLICE PLATE-

5.14 The tower is erected by joining abuttingleg angles using bolts and splice plates. For

economy in fabrication, only two sizes of spliceplates are used. One is 1-1/2 inches wider thanthe other, and has an extra hole for a step bolt.Both plates are the same length and each providestwo groups of seven bolt holes. Fig. 9 shows thestandard plate used at all leg splice locations wherestep bolts do not occur.

5.15 Bolt requirements at leg splices are asfollows:

LEG SIZE(INCHES)

4x4x5/16

4x4 xl/4

3-1/2 X 3-1/2X 1/4

3x3 xl/4

NO. OF BOLTS AT EACH END(EACH SPLICE PLATE)

7

6

5

4

2-1/2 IN,

2-1/2 IN.

/4 IN

/

f

7/8 IN

\

o

/’-’-”

“T2-3/4 IN,

4

2- 1/2 IN

‘t

2-1/2 IN

4

2-1/2 IN.

)

20-1/4 IN.

Pig. 9—Standard Splice Plate

Page 9

SECTION 760-925-330

Note that only the largest size leg members useall fourteen bolt holes, while the smallest size legsare spliced with only eight bolts, thus leaving sixunused holes in the splice plate. A11 holes inleg members must contain bolts at splices. Alltop sections are made with 4- by 4- by 5/16-inchangles, regardless of tower height. Details on sizeof leg members in other parts of these towers areshown in Fig. 5 and 6.

5.16 Members which have been bent or buckledshould be replaced. Occasionally it will be

found that holes do not line up closely enough topermit bolting without drifting of holes. There isno objection to removing excess zinc (galvanizing)which may have unduly reduced hole size. iMemberswhich cannot be joined without further fieldfabrication should not be installed without checkingdimensions to determine the nature of the mistakein fabrication. Members which are merely too longmay be cut to proper length, provided distancesbetween bolt holes are correct and edge distanceswill be correct after cutting. Grinding may bepermitted in lieu of cutting; cutting by torch shouldnot be allowed.

5.17 Freshly cut surfaces, or any surface wheregalvanizing has been damaged should be

painted immediately. The best protection is probablyprovided by the zinc-rich type of paint. Thesepaints are 90 percent (or more) powdered zinc andwill provide some galvanic protection in the samefashion as galvanizing. They also have the propertyof preventing rust from creeping under the paintfilm. They should not be applied to steel whichis damp or wet, or coated with mud, oil, grease,mill scale, bird droppings, etc. To be effective,paint of this kind should not have a spreading ratewhich exceeds 350 square feetigallon. If this typeof paint is not available, zinc oxide—zinc dustpaint—is an acceptable substitute. It should beapplied over clean, dry metal and should conformto Federal Specification TT-P-641O Type I or Type H.

5.18 The tower has a series of 9116-inch holesspaced 16 inches apart on alternate sides of

one leg to accommodate step bolts which provideaccess to the structure. All step bolts are to beinstalled with a plain washer, a hex nut, and aPALNUT. Step bolts usually extend from thebottom of the tower to a point 5 feet above thegrating platform at the lower end of the top section.However, they may be omitted in the bottom 8

feet of the tower to discourage unauthorized climbing.This precaution is unnecessary if the tower baseis surrounded by a fence with a locked gate.

5.19 Each leg member has also been punchedwith three 9/16-inch holes in the same flange.

Facing the tower, these holes are on the right legof the tower face, are located 3, 13, and 18 feet,respectively, above horizontal bracing members ofeach panel, and have been provided to accommodatewave guide restrainers. These holes will normallybe left unfilled unless wave guide is to be installedon the tower.

5.2o An extra hole is provided in each leg ofthe tower to accommodate a 6M safety

strand. (See Section 081-725-200. ) These holes arelocated 4 feet above the horizontal bracing membersin all but the top panel. The strand is ordinarilyused only at the level having side obstructionlights, and is intended to provide protection forworkmen who have occasion to service those lights.

5.21 A platform consisting of three pieces of steelgrating (16 by 32 inches) is provided at the

lower end of the top section in all towers. Eachpiece of grating is fastened in place by four gratingclips equipped with 3/8- by 1-3/4 inch bolts withnuts, washers, and PALNUTS. The generalappearance of the platform is shown in Fig. 10.

5.22 The general appearance of the top sectionis shown in Fig. 11, which also shows the

location of mounting holes used with various kindsof radio equipment. Note that the second horizontalmember above the star mount is skewed, ie, nothorizontal. This is deliberately done to accommodatethe backstay of 8- and 10-foot parabolic antennas.Note also the requirement for double spacer washersat the crossing of the lacing angles marked A-A.

6. GUY TENSIONS

6.01 Measurement of guy tensions should beundertaken only under relatively calm or

windless conditions. Since ambient temperatureshave an appreciable effect on tension, Tables A,B, C, and D show the correct tension (T), and thecorresponding time (S) for 20 oscillations at differenttemperatures for the four sizes of guys. Tensionsshould be set within +5 percent of the specifiedvalues.

IPage ~0

1ss 1, SECTION 760-925-330

APPROX 4 FT

— 2 “ 8 ‘N”~I

[I FT 4 IN, P/’a

GRATING CLIP

STEP BOLTS

Fig. 10—Tower Platform

6.02 It may be desirable to use a greater numberof oscillations to improve the accuracy of

measurements. This may be done by adjustingthe indicated time in proportion to the oscillations,eg, time for 30 oscillations would be 1-1/2 timesthe value for 20 oscillations.

6.03 The formula for determining the elapsedtime for any number of oscillations for any

length of guy of any material at any tension is:

S = 0.352 NL m

where

S = time in seconds

N = number of oscillations

L = length of guy in feet

W = weight of guy in pounds per foot

T = tension of guy in pounds

Page 11

SECTION 760-92$=

MOUNTING PLATE FOR AIR OBSTRUCTION LIGHT

/

/

4

HOLE5 FT

I

~ PLATES FOR REFLECTORMoUNTING BRACKETS

HoLES FOR REFLECTOR’

PIPE BRACKET

HOLES FOR PIPEBRACKETS OF 8 FTANO 10 FT ANTENNAS

\ sTAR MOUNT

Fig. n-location of Mounting Holes for Equipment

Page 12

1ss 1, SECTION 760-925-330

Since the design tension is given, the formula forthe time for a predetermined number of oscillationswill reduce to:

S = KL

where

S = time in seconds

K = a constant, (0.352 NF

‘T)

L = length of guy in feet

Tables A, B, C and D also show the values of Kfor the specified tension at each temperature range.‘l’able E shows the length of the oscillating sectionof the guy for each height of tower on leoelground.

6.04 If there is a difference in ground elevationbetween the location of the pier and the

anchors, the length of the oscillating section willhe different from the values shown in Table Eand the time periods shown in Tables A, B, C,and D will not apply. In the case of top andmiddle guys, each foot of elevation difference will

;ause a difference of 1.41 feet in the length ofthe guy. In the case of bottom guys, each footof difference in elevation will cause 2.0 feet of

difference in the length of guy. The lengths shownin Table E should be increased if the groundelevation at the anchor location is lower than theground elevation at the base pier, and decreasedif the ground elevation at the anchor is locatedabove the ground elevation at the base pier. Thelength of oscillating section, as adjusted for differencein elevation, should then be multiplied by the Kfactor (corresponding to the height of tower, guysize, and temperature involved) to obtain the time,S, for 20 oscillations.

6.05 The tower should be checked to see that itis plumb after the correct guy tensions have

been reached. It is preferable to make observationsfor plumbness with the aid of a transit. Thetower should not deviate from vertical by morethan its total height divided by 720. The maximumallowable deviation between guy points is obtainedby dividing the distance between the two guypoints by 720. Section AG25.300 discusses proceduresfor observing tower plumb and bow.

6.o6 After the tower has been plumbed and thecorrect guy tensions have been set, the jam

nuts of the turnbuckles should be tightened. .%a further means of discouraging tampering, turnbucklesat any anchor may be locked together by a loopof strand. This precaution is unnecessary if theanchors are enclosed by fences with locked gates.

Page 13

TABL

EA

—TI

ME

FOR

20O

SCIL

LATI

ON

SIN

SEC

ON

DS

1/2

-lNC

HG

UY

S TOW

ERH

EIG

HT

180

FEET

(L:S

) ‘-”1

‘--s

(SEC

)

120

FEET

220

FEET

I16

0FE

ET14

0FE

ETTE

MPE

RATU

RE

T(L

BS)

s(S

EC)

11.4 8.8

11.6 9.0

11:8 9.2

1~.) 9.5

12.2 9.8

12.5

”-

10.1

K(1

:S)

——

.071

649

20

——

.073

946

10—

.—

—

.076

343

10

——

,079

040

00

——

.082

136

90

(S:c

)

— 11.3 . 11.6

. 12.0

— 12.5

— 13.0 .

—— 13.6 — 14.4

KT

(LBS

)

— 4880

(1:S

)

—K

Ks

[SEC

)K

s(S

EC)

— M L M L M L M L M L M L M L —

1

.067

1

.065

3

.068

3

.067

0

.069

4

.068

7

.070

7

.070

7

.072

0

.072

8

.073

4

.075

1

——

4870

13.2

Bel

ow–1

0°

—10

°to

+10°

10°

to30

°

30°

to50

”-’

5540

5860

5360

5570

5180

5290

5000

5000

4820

4710

4640

4430

4460

4140

—— 0713

— 10.0

— 10.3

— 10.7

— 11.0

—

,071

5

— 4940 — 4630 — 4310 — 4000

—

3690 — 3370 — 3060

.071

18.

1

— 8.3

—

—,-

-_:

——

,073

9

—

,076

3

—

,079

0

—

,082

1

—

,085

5-—

—

,089

5

— 0736

—

0761 —

,079

0

— 4580 — 4290 — 4000

.073

545

8013

.6—

—

.076

18.

642

9014

.1

— 14.6

—

.079

09.

0

— 9.3

4000 — 3710

——

50”

to70

°— 08

23

— 0858

——.

——

,091

1

— 3710

— 11.5

— 12.0

— 12.5

.082

315

.1

—70

°to

90°

— 9.8

—

“-+”

-— —

.085

533

90

——

.089

330

10

— 3420

.086

134

2015

.8

12.7

10.4

.074

8.0

777

Abo

ve90

°—

— 1120

— 16.5

.090

310

.331

30

dK

=.3

52N

:f

=4.

998/

T

,---

--

M=

Mid

dle

Gu

ysL

=L

ower

Gu

ys

TA

BLE

B—

TIM

EF

OR

20O

SC

ILLA

TIO

NS

INS

EC

ON

DS

9/16

-lNC

HG

UY

S

TO

WE

RH

EIG

HT

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SECTION 760-92S

TABLE E — APPROXIMATE LENGTH OF GUYIN OSCILLATION — LEVEL GROUND

TOWERHEIGHT

(n)

80

100

120

140

160

183

200

220

240

260

280

300

To?GUYS

(Fl)

92

120

149

177

205

233

262

290

318

346

375

403

BOTTOMGUYS

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—

—

114

140

158

185

203

134

152

179

179

197

MIDDLEGUYS

(FT)

—

—

—

—

—

—

—

170

198

227

227

255

page 1818 Pages