BSTJ 10: 3. July 1931: New Standard Specifications for Wood Poles. (Jones, R.L.)

5.4 MB·English

[New Standard Specifications for Wood Poles
By Rta JONES*

Ti Ae Mee Rutt itr ble ae eee
fining are owed nese pong le
ec am der “fi taht lng a the ence

JREERESENTATIVES of munication, poe ad

‘ransvortation utile, eb peace. cmd of plc vd general
ingcrcets hive cinpecated in Ue yneparation of the ve uniform etand-
se apceifictione vor ove! jwise that were relly approved By the
American Stamlarde Assxenion! The new ebevitiations cover dix
‘ncasions anu waterialrequiremens fo worshern waite cedar, western
‘al eadee, ches ed smichesa pte ples, bye res for peeservaive
leearment ie to: inched. Speciteasione for lige pine ard
Dougies eee are in preparation.

Pale specications deal with natural rather than fabsieated pr
tetas Heretofore, he lige: utilities hase qrrisaed poles of the
Various epeciee tnd seins that hae grown up mone re
Independently= Confusing cllereners iz maccial regiment end
Jnvthe dimensions! tables have reat. Esonemi¢ produetion and
tiitmadon require se arrangement af she eatsral ent of pole tibers
nto groups ct! either by toy liamcters ard lengths, by classes
Sishichelrcun eces a¢ the toy sd ULL ere speed i adcion
to Yength, Te flier designations. such ge 4, Sand C, that have
bho spied co these eases have Rad no rewnsion meaniag. A pole
torgiee Teng th and claw we species he not generally been equiva

fen steel fating to one of hese feng and ease fore
srry aint in mit ces, se Tanger poles Even clas have not
Ina the sane stenitn sling as che shorter poles et the sane ease

ie peliaps quite obvious shat beers rational imprvement could
tae ia the sys of dimensonal classibeation, it was seuessecy
tociecte a fovncaln for compariea ofthe stents of the citferent

Sse, Seti) Commires an Won Pus Ameen Salle Ao
tae opeclistions woss approved on Just 20, Ms,
pccloa For illsrative porptese a summary of part of die test re
ule uced in arvvinye ot Titer stress values is chow in Tale 1. A
Aetsled study of the nets of these osrs and of other teste unde it
full length pees wil ow sal clear specimens of Wood of che spies

a ‘ear |
Ciel | xa [ieeceme =
e/g] ea
pad a4

‘under investigetion Jed tothe rcommasdaton of the following Sires
fs standard witimate ber stresses:

asthe white er 200 pv ai

Th ler sire for a ive pie finds apotiation in pale Hine
‘engineering tavaugs tae conversion of dhe sors value "sm forms of
‘momen of ssistasee. vay ct the growad line ‘The pf art 4
feviesof supports ov the wires, With thi in ind ore a the etcien
ondered in connection with the appliestin af the new ber sons,
hich is cial here by way of Slantation, was dizected toward an
halves of the vavation in sine and variation ia medulus of rupture
that might be expected to afert the average gourd fine moment of
esis nf radon 3 pole grape. Approximately 400 crested
fouthern vine and S00 western rel cular, clases, thirly fooe (see
{Table 2 poles were ussd sa this yuesicular study. Tt ws found dt
Snore Inn 8 per cert. of the pte she average moment of resistance
GF sock Sopce groups wee alzher thax che minimor ca‘eulated for
the ive vlass wad Tength, ‘The result ia considered rersnnably cep
eoentuivs of wat would Be fond in 6 similar study of rer sizes
fe may be comcuedl that with the new standard fer stress values
as ¢ bese practaly all pares of» Bre when new should be equal to
Gr Bester than Ue strength seting for the spcified nan of the
lass of ples utr and thae wher se recaced loade under the eon
iione ueualy ebtemning in {38 higher grads of eoustuccion are
onsite, the bending mint developed st he ground Sine show
Farely, 3" even, aparoach the seal momen: of reitlane,

‘Since the standard ultimate ber etewos are lanes! upon tests of
repmmventative poles, theyre lieved to be sitieGicnry Fr all ordic
hhary nurs, ‘They aze drei applicable in the engineering of pole
Tee widhoas further areatment of compensation for kaot, variation
Sn melsiure soste-t, ar density f wood, In amy se, the question of
‘ati saasfcntion sway ne iat for practical purpoees co soutien
toe poleesandsfucien of eueren: proctcLa show chat approxi: ly
4s per cent cl surk ies passing chron the producers! yards could
bi elasacd as dene. The erosatingpeooees stem ty eluce the
tiation fowne fn the modulus of ruptuce values of mireates] poles.
‘The comparatively low eoebicient of variation ef ercorted wouern
Dine shown in Table 1 indieates that for generel pores an attempt
ocestfy rine pole according lensty is an unreersccy rednement

With the esneed ber etree Tes, dimension tables for the
four species were developed in accordance wih the (olowiag prin

{@) The tales should specify imenvions in teem of circumference
Tn inches at che top, amd ceumferenre i inches at sx feet
fram the butt for ples uf the respective lege and clases
xref des clatoe with "no butt reuirentens,

(0) Allies of the same lengih and elses should have, when sew
Tanmrosimecely ual rsagth, or a mone pwcelse forms, ul
aoente of ces ac che groend line

{6 AN poles of difecnt lengths thin The same class shuld be of
suitable sizes co withstand approximately the vane breaking
‘ad essing that the lad is appiied two feet fom the cop
sd hat the break would ascur at the ground lie
|) Tie classes Com the lowest to the highest sould be oxzenged ia
“npfoximace geometric progreesion, the increriexs in bresking
‘aed berseen classes being ebout 25 per coat.
em" iin aecoré with che prelerred number princpla, ard the
increments chosen provide the lowest number of classes thst are se
"Tables of ten clasee for each speci, as shaven in ‘Table 2, have
‘been made a pact of che standard specications. Classes 8, 9, and 10,
Alene simply hy aisimum top elreumererces, have been provided
to cover poles purchased on a top size basi or tor rural or other
Ugly oaled tines, Clases £ t0\7, defined primacily by tele cir
‘unferenoes at six feet ton the ust have bech designed to meet the
following breaking loads in pounds, assuming the cndltins of item

Cass 14800 Class 51900
(Case 2—3700 Clase 62500
(Clas $2000 Class F 1200
(Ces 42400

‘The requited cirumlerences at the grou line for che respective
paces were calculate Ly means of she formula My — o002O4E C%
which isthe wellkzows desire fo:nmit applied to cartilevsr beam
bf eeu eevee aeetion, rd resin t ft pour wri. Te gro
Sine circursferences thus obese! were cumvered int cirramference
‘lie fel Tren the butt by means ol appa average taper vale
for che cespecsive species

‘The breskng leas are ratings for the minimum size pole for the
tivea length and class based on the stancred imate fer stres for
the species. ‘The average pole of given else wl nally be come
‘vably stronger than the class rating. The choice of sizes provided
in the tables is auficienty extensive te enahle the engineer to make
dan ccomumical election of oles tweet spel eueiente afer the
ead eonditins af the line have ler eles

(Grapes! ehart have been prepared which show the relation be
tovcen the dimeasion tables ef some current specications and the ew
ilule. These ebarte shoule be of mterial assist te suppers
land constimers whe wth to comps He al wt Ie ne fr encore
Grrecotd pupae. Represenative bel “rom the vhosts appear
Tig. Coneparicons forall ngths and estes say be foun in te
famplete ehorts that are cb malble oa tle Atveriean Stanlaed

‘Aaeslacon
su NUL SUSE PROMEECAE SOERNAL

E

3

Employment of tie new standard lima er stesses of stood
poles 1 provits for uuver cule 261-40 of the National Salety Code.

With the revises mecesieagee by their aypion, Tele 20 of the
Coc will appeat as indicated fy Tele

niin os
oer

2 Ge

a. 1 Seymour Ue thet ert fr hy yo

‘The material recuiremats of the several specifications eover shape,
end straights of erin sad lit or probibit auch delecrs ab knots
hecks,iaece demage unl Secey, Withsatcetaedceferenee to what
Sige called the appeavarce rayu'reriests, ic may’ be said that the

sgcifcations defice poles of # quality chat the mjor ules have
found tobe waisaetoey, Departures ors straightenes ee wid within
practical Hits hae nlinary wee

Decay ard the presence oF woudso:ting fang are generally pro
hibited” Minor exeeptions are ride with fespeet eo the Iniln of the
fears, which swe snually ented with execeote, The question of
including poles cut fom sound eel Lees received careful mons
fiom, lighted chests ie aecepvalile wich ee-ten resections, but
inthe care of ue other three species ples from vs ster ave peci-
fied. While fe migne appsir momento salvage ave use al sound
(dead tr: tending in t2e won, recal opinion a yrewut story
favors eliinasing deed timbers a sousce of pls material bees
ff the extra costs involved in anling aad inspection

[fue proved impractcsble ts lie checks in prevve: manner
(cheeks of lemechwise separations of the seed fibers vary ne
Ith che ze, mesiing, ad reine cent of Cae pole hat fought
Mlefnite limitation sweaved desirable the cumpromise finally adopced
Tene which stoly prchibite injuring check. Practically the matter
2 ft the fudge of he euppe> am comstme™ cer

(FT |

‘Phe Hinitaton of knwte was a master of soeral wdy. Previous
specliatinna Wwele-at variance end. dara were Lacing (9 establish
EEceptable Limite, Mensuraments af knots fager than ne haf ich
‘wore therefore made on repwesentative poles ofthe for meen. "The
Her and Toeaton of out Gventy-thrwe Liousard nets in gore S67
LEW STASDAND SPNCIEICATIONS FOR W500 POLES

poles were tabulated, and ac stight have been easefpared, the occur
Fenn af large kn large groupe ef knots were found inven

Seth he eth af pe THis le bo a dvs he sa it
froup for short poles and ose for lang poles cf ecch speciae. Figure 2,
Farstushern pine, ia typieal illustration ofthe curves drawn fora the
dla. It ahows, fst the per sexe ot poles chat have single kot ol
he gives diameters, (4) for pels up 0 48 fet long, snd (for pol
3 fete longer: and sean, the par cent of pales having groups of
uote widh the iitirated suns of disteane it any 12 nh section,
sepetetely plotted for the same two cases, The limite eet Oy this
unc es shige knots ane for groups of knots iz a uelve inch section
fre shown ie Tali

panto Jom] a a | at
REESE ST eran

‘The standard vefesed to shove which have len prepari ant
npwavell under the procedive of the American Standards esata
Sie rine in mimes. Cine presetber the ulsimece iter etree ar
poles or northern white cedar, wescern red cedar, chestrur and towth-
fen pine, and four presrie che cimensimal ciesifeations far exch of
The here spies coring to lenthe ane! eirsomfeens a3 x08

jn Table 2. These five are Avera Signals. Tie itestorn we
respect te check aa del var led ta recommending the eran
fur spesfcations civering lara requirements an American Tenta
tive Stanardse ‘They ace the fat America stan fer wea pokes
ara their alot on the stud asi outlsed inchs tx Eanoraut
ftep coward simplified. proccce in an eerentish public utliey come
rtity

‘The appiction of the result ofthe work, a: issue of othe: well.
emotes sievdalitary presse, slum yied! mre enginecring