IS 4998-1: Criteria for design of reinforced concrete chimneys, Part 1: Assessment of loads

19 Pages·1992·1.8 MB·English

by  Bureau of Indian Standards

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IS 4998-1 (1992): Criteria for design of reinforced
concrete chimneys, Part 1: Assessment of loads [CED 38:
Special Structures]
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IS 4998 ( Part 1 ) : 1992

CRITERIA FOR DESIGN OF REINFORCED
CONCRETE CHIMNEYS
PART 1 ASSESSMENT OF LOADS
( Second Revision )
UDC 697.8 [ 691.328-l ] : 624.042

@ BIS 1992
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR h&utG
NEW DELHI 110002
November 1992 Price Group 6
laicepS serutcurtS lanoitceS ,eettimmoC CED 38
FOREWORD
sihT naidnI dradnatS ( traP 1 ) ( dnoceS noisiveR ) was detpoda yb eht uaeruB fo naidnI
Standards, retfa eht tfard dezilanif yb eht laicepS serutcurtS lanoitceS eettimmoC had neeb
devorppa yb eht liviC gnireenignE noisiviD .licnuoC
sihT standard was tsrif dehsilbup ni 1968 as SI 4998 and yltneuqesbus desiver ni 1975 ot revoc
eht stnemeriuqer fo eht larutcurts ngised as llew as assessment fo sdaol rof decrofnier etercnoc
.syenmihc nI this standard ( traP 1 ) assessment fo sdaol no decrofnier etercnoc syenmihc has
neeb .derevoc traP 2 fo this standard lliw revoc ngised airetirc fo decrofnier etercnoc .syenmihc
ehT snoitadnemmocer fo eseht standards ylppa ylno ot syenmihc fo ralucric .noitces-ssorc
syenmihC fo ralucric-non noitces-ssorc yam ecneirepxe rehgih tcerid wind sdaol and erom
xelpmoc cimanyd stceffe hcus as .gnipollag nI hcus ,sesac tsilaiceps ecivda shall eb deniatbo
rof gnitamitse wind .sdaol
ngiseD rof cimanyd stceffe fo wind and cimsies secrof seriuqer deliated .noitagitsevni nehW
lareves syenmihc era detacol esolc ot hcae ,rehto ro nehw eht syenmihc/yenmihc era detacol
esolc ot rehto serutcurts fo elbarapmoc ,thgieh ledom stset ni wind slennut shall eb deirrac tuo
ot assess eht gniteffub smelborp that yam .esira ehT ngised snoisivorp gnitaler ot cimsies secrof
era derevoc ni SI 1893 : 1984 airetirC‘ rof ekauqhtrae tnatsiser ngised fo serutcurts htruof(
revision )‘.
nI eht noitalumrof fo this standard eht gniwollof snoitacilbup evah neeb detlusnoc :
AC1 88-703 dradnatS ecitcarp rof eht ngised and noitcurtsnoc fo ecalp-ni-tsac decrofnier
etercnoc .syenmihc naciremA etercnoC ,etutitsnI ,toirteD .hciM 48219, USA.
SA 9891-2.0711 SAA gnidaoL edoc : traP 2 : Wind .sdaol Standards noitaicossA- fo Australia.
ledoM edoc rof etercnoc ,syenmihc traP A : ehT llehs ( rebotcO 1984 ) dehsilbup yb
CICIND.

decudni-dniW sdaol no decrofnier etercnoc syenmihc yb .J.B ,yrekciV lanoitaN ranimeS no
llaT decrofnieR etercnoC ,syenmihC lirpA 1985, weN .ihleD
,92007-UDSE dehsilbup yb ,UDSE .nodnoL
ymawsanhsirK ,.N.T oaR ,.V.N.G alusavruD .S and yddeR .R.K ledoM‘ snoitavresbo fo
ecnerefretni stceffe no yrotallicso esnopser fo lacitnedi .’skcats .corP ht4 .tnI .fnoC no
Wind stceffE no .sglB and .rtS ,worhtaeH pp. .412-902 1975.
oaR ,.V.N.G dniW‘ stceffe no llat .’syenmihc Asia cificaP muisopmyS no Wind ,gnireenignE
rebmeceD 1985, ytisrevinU fo ,eekrooR .aidnI
oaR ,.V.N.G alusavruD .S and yddeR .R.K ledoM‘ seiduts no wind stceffe no llat decrofnier
etercnoc .’syenmihc lanoitaN ranimeS no llaT decrofnieR etercnoC ,syenmihC lirpA 1985,
weN .ihleD
)1 : 2991
IS 4998 ( Part
Indian Standard
CRITERIA FOR DESIGN OF REINFORCED
CONCRETE CHIMNEYS
PART 1 ASSESSMENT OF LOADS
(Second Revision
1
1 SCOPE d evitceffE retemaid nekat as egareva
retemaid revo eht pot 3/l thgieh fo
sihT standard ( traP 1 ) srevoc eht assessment yenmihc ni m
fo sdaol rof decrofnier etercnoc .syenmihc
E A erusaem fo eht elbaliava ygrene
2 REFERENCES ni eht wind at eht larutan -uqerf
ycne fo yenmihc
ehT gniwollof naidnI Standards era yrassecen
e ecnatsiD neewteb lartnec enil fo
stcnujda ot this standard: eht llehs and eht ertnec of ytivarg
fo eht lacol daol ni m
IS No. Title
f l;utany ycneuqerf fo eht yenmihc
456 : 1978 edoC fo ecitcarp rof plain
and decrofnier etercnoc
fi Natural ycneuqerf fo eht yenmihc
( third revision ) ni eht ith edom fo noitarbiv ni zH
1893 : 1984 airetirC rof ekauqhtrae G tsuG rotcaf
tnatsiser ngised fo serutcurts
a? kaeP rotcaf denifed as eht oitar fo
(fourth revision )
eht detcepxe kaep eulav ot eht
edoC fo ecitcarp rof ngised RMS eulav fo eht gnitautculf daol
875
sdaol ( rehto than -htrae
ekauq ) rof buildings and H thgieH fo yenmihc ni m
serutourts : ka cimanydoreA damping tneiciffeoc
ot eb nekat as 0.5
( trap 1 ) : 1987 daeD sdaol
( traP 2 ) : 1987 desopmI sdaol &i Mass edom damping fo noitarbiv retemarap rof eht it”
( traP 3 ) : 1987 Wind sdaol noitalerroC htgnel ni sretemaid ot
L
eb nekat as O-1 ni eht ecnesba fo
3 SYMBOLS etauqeda dleif data
slobmyS desu ni this standard shall evah eht me tnelaviuqE mass rep tinu htgnel ni
gniwollof ,gninaem unless esiwrehto denifed eht tsrif edom fo noitarbiv ni m/gk
erehwesle ni this standard: mei = tnelaviuqE mass rep tinu htgnel ni
aerA fo eno etercsid ekarts ni 2m eht ith edom fo noitarbiv ni m/gk
A, =
B = dynluowrgokclaBs gniyrav rotcaf tnenopmoc gnitacidni fo wind eht mz = yMeasns at rep noitces tinu z htgnel ni m/gk fo eht -mihc
daol noitautculf Mk = tnemoM eud ot lebroc daol ni m-N
CD = Drag tneiciffeoc fo eht yenmihc ot Moe = lanretxE and lanretni gnir stnemom
eb nekat as 0.8 and eud ot laitnerefmucric wind secrof
kaeP yrotallicso tfil tneiciffeoc ot toM ni m/m-N
CL =
eb nekat as 0.16 zp = ngiseD wind erusserp ni N./ma at
RMS yrotallicso tfil tneiciffeoc ot thgieh z
CL =
eb nekat as 21-O zP = ngiseD erusserp at thgieh ,z eud ot
retemaiD fo yenmihc at thgieh z ylruoh naem wind, deniatbo as
d, =
ni m 0.6 ,2v ni 2m/N
SI 4998 ( traP 1 ) : 1992
Y = eciwT eht ecnelubrut ytisnetni 4.2 Imposed Loads
r, = naeM radius fo llehs at eht noitces desopmI sdaol shall eb nekat ni ecnadrocca
rednu noitaredisnoc ni m htiw SI 875 ( traP 2 ) : 1987. ehT desopmi
sdaol no lanretni mroftalp and dooh fo -itlum
S = eziS noitcuder rotcaf eulf syenmihc shall edulcni etairporppa sdaol
s, = lahuortS rebmun ot eb nekat as gnirud .noitcurtsnoc
0.2
4.3 Wind Loads
ud, 1
t = I -6&+_ - } 4.3.1 Wind sdaol shall mrofnoc ot SI 875
i ZiZ z =zj Zei ( traP 3 ) : 1987.
st = ssenkcihT fo llehs at eht noitces
4.3.2 ehT erudecorp rof gnitamitse sdaol no
rednu noitaredisnoc ni m syenmihc eud ot wind shall eb as nevig ni
ll = Wind deeps ni tes/m xennA A.
oE = ylruoH naem wind deeps ni tes/m 4.4 Earthquake Loads
at 10 m evoba dnuorg level = Vb.
ekauqhtraE sdaol no syenmihc~ shall eb -upmoc
,ii erehw Vb and &I era as denifed
det ni ecnadrocca htiw SI 1893 : 1984 using
ni SI 875 ( traP 3 ) : 1987
eht seicneuqerf detaluclac as rep noisivorp ni
V cri = lacitirC wind deeps rof hti edom fo xennA A.
noitarbiv ni tes/m
w = daoL no lebroc ni N 4.5 Temperature Effects
lamrehT gnidaol sdneped nopu eht laudividni
z = thgieH fo yna nojtces fo eht -mihc stnemeriuqer fo syenmihc and yeht dluohs eb
yen ni m derusaem morf eht pot fo
deredisnoc .ylgnidrocca
noitadnuoF
ttz = thgieH at hcihw dz4+,i/l/t is a -ixam 5 TNEMSSESSA FO SDAOL
,mum ni eht hti edom fo ,noitarbiv
ni m 5.1 daoL ot eb deredisnoC
u = rewoP law tnenopxe ehT suoirav sdaol ot eb nekat otni tnuocca
B = larutcurtS damping as a noitcarf rof ngised fo syenmihc shall eb as :swollof
fo lacitirc damping ot eb nekat as
01016 )a daeD sdaol gnidulcni desopmi ;sdaol
)b laretaL and laitnerefmucric wind ;sdaol
cimhtiragoL tnemerced fo -curts
6s =
larut damping = 2~1j )c ekauqhtraE ;sdaol and
ytisneD fo ria ot eb nekat as 1.2 )d tceffE fo ,erutarepmet htob yllacitrev
(I = and .yllaitnerefmucric
3m/gk
ioq = kaeP pit noitcelfed eud ot xetrov 5.1.1 roF eht llarevo ngised fo yenmihc llehs
gniddehs ni eht it” edom fo -arbiv and ,noitadnuof desopmi sdaol deen ton eb
noit ni m .deredisnoc ,revewoH rof ngised fo laudividni
n = tnelaviuqE tcepsa oitar larutcurts stnemele- hcus as ,smroftalp ,cte and
rof lacol gninehtgnerts f@ eht ,llehs etairporppa
4 iz = edoM epahs noitcnuf dezilamron desopmi sdaol shall eb .deredisnoc
htiw tcepser ot eht cimanyd -ilpma
edut at pot fo eht yenmihc ni eht 5.1.2 Wind and ekauqhtrae sdaol shall ton eb
it” edom fo noitarbiv deredisnoc as gnitca .ylsuoenatlumis
4 LOADS 5.2 ehT noitadnuof ngised dluohs osla eb
dekcehc htiw muminim thgiew fo yenmihc
4.1 Dead Loads rednu llehs enola noitidnoc denibmoc htiw
gnitsixeoc laretal .sdaol
daeD sdaol shall edulcni eht thgiew fo yenmihc
,llehs ,sreniJ renil ,stroppus rehto seirossecca roF a denil ,yenmihc eht rotcaf fo ytefas
and daol fo ash and toos as .elbacilppa tinU against gninrutrevo fo noitadnuof shall ton eb
thgiew fo eht slairetam shall eb nekat ni less than 1.5 rof llehs enola esac and shall ton
ecnadrocca htiw SI 875 ( traP 1 ) : 1987. eb less than O-2 rof eht detelpmoc .yenmihc
2
SI 4998 ( Part 1 ) : 1992
53 Loading Conditions erehw
ehT suoirav daol snoitidnoc rof eht ngised fo Moe and MO1= lanretxe and lanretni gnir
stnemom
yenmihc llehs shall eb :
PZ = ngised wind erusserp at thgieh z ni
)a daeD sdaol ,2m/N and
)b daeD sdaol + wind sdaol mr = naem radius fo eht llehs at eht -ces
noit rednu noitaredisnoc ni .m
)c daeD sdaol + ekauqhtrae sdaol
ehT ngised wind erusserp ( zp ), rof eht -mucric
)d daeD sdaol + erutarepmet tceffe
laitneref gnir ,stnemom shall eb deniatbo ni
)e daeD sdaol + wind sdaol + erutarepmet ecnadrocca htiw SI 875 ( traP 3 ) : 1987, -aert
tceffe gnit eht yenmihc as Class A .erutcurts
)f daeD sdaol + ekauqhtrae sdaol + -met
ehT pooh ecrof and raehs e-ud ot gnillavo deen
erutarep tceffe
ton eb .deredisnoc
)g laitnerefmucriC tceffe eud ot wind
5.5 Moment Due to Corbel Loads
)h laitnerefmucriC tceffe eud ot -arepmet
erut tnemoM eud ot sdaol no ,slebroc Mk is :
)j laitnerefmucriC tceffe eud ot wind + kM 3 &+W.e
erutarepmet ( g + h ) erehw
&h = tnemom eud ot lebroc ni ,m-N
NOTES
w = daol no lebroc ni N, and
1 dniw-ssorcA sdaol llahs ebA denibmoc htiw eht e = ecnatsid neewteb lartnec enil fo
gnitsixe-oc dniw-gnola .sdaol ehT denibmoc ngised
tnemom at yna noitces llahs eb nekat sa eht toor eht llehs and eht ertnec fo ytivarg
mus erauqs fo eht stnemom eud ot eht -ssorca fo eht daol ni .m
dniw sdaol dna eht gnitsixe-oc dnii-gnola .sdaol
revenehW eht lebroc is evoba ro woleb an
2 gnidaoL snoitidnoc )b( dna )c( llahs eb deredisnoc
rof llehs enola esac .osla ,gninepo eht .tnemom Mk shall eb nekat
3 yradnoceS stceffe eud ot noitcelfed llahs eb -noc =fW. e.
deredis rof eno .elcyc
nI eht evoba alumrof ( _t ) and ( - ) refer ot
4 ngiseD dluohs osla redisnoc stceffe eud ot lacol
noisnet no renni ecaf fo eht llehs evoba eht
,sdaol fi ,yns no eht .llehs
lebroc and retuo ecaf fo eht llehs woleb eht
lebroc .ylevitcepser ehT tceffe fo this yam eb
5.4 Circumferential Wind Moments nekat as detubirtsid revo a htgnel tnelaviuqe
ot eht shtped fo eht lebroc at eht noitcnuj htiw
ehT laitnerefmucric gnir stnemom eud ot wind
eht llehs ro 467-O ( mr tR ,) ni m revehcihw is
era detaluclac yb eht :alumrof
,retaerg and ts is eht ssenkciht fo eht llehs at

Moe ro MO1 = 0.33 .zp r‘& ni m/m-N thgieh eht noitces rednu .noitaredisnoc

ANNEX A
( Clauses 4.3.2 and 4.4 )
WIND LOAD CALCULATION FOR REINFORCED CONCRETE CHIMNEYS
.retemaid ehT tluser lliw evig eht wind daol
A-l WIND EFFECT ON CHIMNEYS
rep tinu .thgieh nehW a retsulc fo syenmihc
A-l.1 Static or Along-Wind Load with or With- is ,tneserp cimanydorea ecnerefretni neewteb
out Aerodynamic Interference meht yam esaercni eht latot wind .daol -oreA
ehT wind daol no an detalosi yenmihc ni eht cimanyd ecnerefretni shall eb deredisnoc rof
noitcerid fo wind at ynaz thgieh yam eb -amitse dniw-gnola daol ylno fi eht gnicaps neewteb
det yb gniylpitlum eht ngised wind erusserp at eht ertnec senil fo eht syenmihc is less than 3
that thgieh yb eht gard tneiciffeoc ( CD ) and semit eht evitceffe retemaid fo eht tsegral
3
IS 4998 ( Part 1) : 1992
.yenmihc ehT tnemecnahne ni wind sdaoI wind deeps and nehw this ycneuqerf sedicnioc
lliw eb eud ot an esaercni ni eht eulav fo CD. htiw eht larutan ycneuqerf fo eht ,erutcurts
ehT eulav fo C, rof hcae yenmihc detacol eht cidoirep gnicrof noitcnuf lliw eb ni -oser
nihtiw a ecnatsid fo 3 semit eht evitceff.e ecnan htiw eht larutan ycneuqerf fo eht -curts
,retemaid yam eb detaluclac yb assuming eht erut and snoitallicso fo egral sedutilpma nac
eulav fo CD ot eb gnis.aercni ylraenil morf 0.8 ekat ,ecalp semitemos at etiuq wol wind .sdeeps
rof( a gnicaps fo 3 evitceffe sretemaid ) ot a ,yllareneG this gniddehs seod ton ekat ecalp
eulav fo O-2 ( rof a lacitehtopyh gnicaps fo 1 all gnola eht thgieh fo eht erutcurts ni a -er-roc
evitceffe retemaid hcihw seilpmi that eht owt detal .rennam hcuS detalerroc gniddehs sekat
syenmihc hcuot hcae rehto fi yeht era lacirdnilyc ecalp at eht tsom revo eht pot flah fo eht
and lacitnedi .) esehT seulav fo CD ylppa up ot .yenmihc A egral rebmun fo stnemirepxe no
eht thgieh fo eht tseraen gnirefretni ,yenmihc sledom ni wind ,slennut and snoitavresbo no
fi eht syenmihc era fo lauqenu .thgieh tI is lluf elacs syenmihc evah nwohs tah-t cidoirep
elbissimrep ot niatbo erom etarucca seulav fo gniddehs fo secitrov is detaler ot eht egareva
Cn yb gn~iyrrac tuo ylreporp detcudnoc ledom wind deeps yb eht alumrof nS -= erehw
fdp,
stset ni wind .slennut f is eht larutan ycneuqerf fo eht ,yenmihc d is
its egareva retemaid revo eht pot 3/l thgieh
2.1-A Unsteady Forces on a Single Chimney and~u is eht wind deeps at eht level erehw eht
retemaid is is eht lahuortS rebmun eht
d. S,
A elgnis detalosi yenmihc lliw ecneirepxe eulav fo hcihw is ot eb nekat as .2-O hguohtlA
ydaetsnu wind secrof eud ot owt main ,sesuac ti yam raeppa that ecnanoser lliw ekat ecalp at
yleman ( i ) cidoirep xetrov ,gniddehs and ( ii ) a ralucitrap wind deeps dellac eht lacitirC‘
ydaetsnu ecrof desuac yb cirehpsomta -lubrut wind ,”deeps ni ,ecitcarp ti is dnuof that -oser
ecne ro/dna ekaw morf serutcurts fo -arapmoc nant snoitallicso tsisrep revo a rediw egnar fo
elb .thgieh tI yam eb assumed that yreve wind sdeeps dnuora eht eulav gnidnopserroc
yenmihc htiw a thgieh erom than 3 semit its ot ,S = 0.2, eud ot a nonemonehp demret as
evitceffe ,retemaid lliw dehs secitrov fo -oppo xetroV“ .”gnikcol sihT ,gnikcol hcihw sdneped
etis sign yletanretla morf etisoppo sides. ehT no eht edutilpma fo ,snoitallicso yam dnetxe
cidoirep xetrov gniddehs is yrev dekram at rof up ot f 10 tnecrep fo eht lacitirc wind
lacitirc-bus sdlonyeR .srebmun nehW eht .deeps ,eroferehT eht erutcurts nac eb -cepxe
ecafrus fo eht yenmihc is neve ylthgils det ot eunitnoc ot ogrednu tnanoser -allicso
,hguor tcnitsid cidoirep gnicrof is ton snoit rof wind sdeeps up ot tuoba 10 tnecrep
tneserp ni eht lacitirc sdlonyeR rebmun evoba eht lacitirc wind .deeps
egnar morf 3 x 5ol ot x2 106. ehT etanretla
gniddehs fo secitrov morf eht owt sides fo eht 2.2.1-A esuaceB fo eht ylevitaler small -kciht
yenmihc lliw tluser ni cidoirep secrof htob ni ness fo eht yenmihc at eht pot derapmoc ot its
eht noitcerid fo wind and ralucidneprep ot ,retemaid seitilibissop fo ”gnillavo‘c -allicso
.ti ehT ecrof that is detareneg ni eht noitcerid snoit lliw evah ot eb denimaxe fi eht retemaid
fo wind is ,dellac yrotallicsO“ Drag ”ecroF fo eht yenmihc sdeecxe 75 semit eht wall
and eht ecrof that is detareneg ralucidneprep ssenkciht at eht .pot
ot eht noitcerid fo wind is ,dellac yrotallicsO“
tfil .”ecrof ehT ycneuqerf fo gnitallicso gard 3.2.1-A nehW eht thgieh ot pot retemaid oitar
ecrof is eciwt that fo eht yrotallicso tfil .ecrof fo eht yenmihc sdeecxe tuoba 20, eht -ibisscp
fO eseht ,owt eht yrotallicso tfil ecrof is yrev ytil fo dnoces and rehgih sedom fo snoitallicso
hcum regral than eht yrotallicso gard .ecrof gnieb deticxe eud ot xetrov noitaticxe nac eb
riehT evitaler edutingam is tuoba 1 : 10 and .detcepxe ecniS eht cimanyd sesserts eud ot
yeht era htob snoitcnuf fo sdlonyeR ,rebmun rehgih sedom fo snoitallicso nac eb hcum
edutilpma fo ,noitallicso ecafrus ssenhguor rehgih than that eud ot eht tsrif edom fo -licso
and thgieh ot retemaid .oitar nehW eht -somta ,noital ti is tnatropmi that eht ngised eb -cehc
cirehp wind has hgih slevel fo ecnelubrut dek rof rehgih sedom fo ,snoitallicso fi dnuof
( retaerg than tuoba 5 tnecrep ,) decrofnier .yrassecen
syenmihc era devresbo ot etarbiv htiw -ilpma
sedut gniniatnoc htob a cidoirep and a modnar 4.2.1-A nehW lacitnedi syenmihc era decaps
.tnenopmoc ehT ecrof ni eht noitcerid fo at less than 20 semit eht retemaid at dr3/2
wind is ,dellac dniw-gnolA6‘ ”ecrof and that ,thgieh eht sedutilpma fo noitallicso fo eht
ralucidneprep ot eht noitcerid fo wind as, maertsnwod syenmihc era dnuof ot eb -ingam
dniw-ssorcA6c .”ecrof deif eud ot cimanydorea .ecnerefretni sihT
noitacifingam is a noitcnuf fo eht sdlonyeR
1.2.1-A ehT ycneuqerf fo gniddehs fo secitrov ,rebmun ,repat ecafrus ssenhguor and ,ylbissop
has neeb dnuof ot eb yltcerid lanoitroporp ot larutcurts damping. hguohtlA ynam ledom
4
SI 4998 ( traP 1 ) : 1992
seiduts evah neeb deirrac tuo ereht seod ton 2-A NOITAMITSE FO WIND SDAOL
mees- ot eb yna citametsys lluf elacs -crusaem
stnem hcihw dluow worht thgil no eht tceffe 1.2-A OWT sdohtem fo gnitamitse fo wind sdaol
fo suoirav .sretemarap ehT detroper ledom era nevig ni 4-A and .5-A ehT tsrif is a
seiduts wohs ediw snoitairav ni noitacifingam deifilpmis dohtem and is ylekil ot dleiy ylthgils
fo eht sedutilpma fo noitallicso eud ot -ydorea evitavresnoc stluser as raf as ssorca wind sdaol
ciman ,ecnerefretni and ti has erofereht neeb era .denrecnoc ehT nosaer rof this, as -ialpxe
dediced ot tneserp eno tes fo tnetsisnoc data den ,reilrae is eht yticuap fo ~basic citsale-diulf
ni this edoc as a .enilediug sihT enilediug noitcaretni ,noitamrofni yltneiciffus elbatpecca
is ot eb desu ot assess ylno eht ecnatropmi fo data no cirehpsomta ecnelubrut ni lareves
eht anemonehp tub eht lautca snoitacifingam parts fo ruo yrtnuoc and ecnesba fo yna -etsys
ehtno lluf elacs erutcurts yam eb less than eht citam lluf elacs noitagitsevni no liat serutcurts
seulav detacidni ereh eud ot eht srotcaf -nem ni ruo .yrtnuoc ehT dnoces dohtem is desab
denoit .evoba ehT mret noitacifingam‘ is desu no modnar esnopser .dohtem
ot etoned eht oitar fo eht edutilpma fo -ssorca
ehT wind sdaol shall eb detamitse yb htob eht
wind snoitallicso nehw ereht is cidoirep xetrov
sdohtem and eht gnidaol hcihw sdleiy rehgih
decudni cimanydorea ecnerefretni ot eht
stnemom shall eb deredisnoc rof ngised fo
edutilpma fo dniw-ssorca snoitallicso nehw
.syenmihc
ereht is on cimanydcrea .ecnerefretni
3-A SNOITALUCLAC FO LARUTAN
FREQUENCY FO YENMIHC NI GNIDNEB
5.2.1-A ehT ecnelubrut ni eht erehpsomta
dnuora a naem wind deeps gnitsisnoc fo 1.3-A ehT larutan ycneuqerf fo eht yenmihc is
snoitautculf fo egral edutingam ni yticolev nac ot eb detaluclac yb using yna fo eht standard
osla eb a ecruos fo egral snoitcelfed and sdohtem gnivlovni noitazitercsid fo eht erutcurts
sesserts ni .syenmihc sihT is demret as -somta and assuming ti ot eb edam fo a suoenegomoh
cirehp .gniteffub hcuS gniteffub yam osla eb lairetam htiw a elbatius eulav fo eht citsale
desuac yb egral serutcurts fo elbarapmoc .suludom ehT gniwollof seulav fo eht suludom
thgieh hcihw era detacol ybraen hcus as fo yticitsale fo etercnoc shall eb deredisnoc
sretsulc fo gnilooc .srewot ehT ngised fo rof gnitaluclac eht larutan :seicneuqerf
syenmihc dluohs osla redisnoc hcus gniteffub
.stceffe nredoM ngised secitcarp dnet ot dnif eht Grade of Modulus of
modnar esnopser fo a yenmihc htob gnola and Concrete Elasticity ( N/m2 )
ssorca eht wind, eud ot a tnelubrut -somta M 25 3-20 x lOlo
,erehp and etupmoc eht tnatluser daol gnola M
30 3.35 x 101o
and ssorca eht wind. M 0’01
35 3-50 x
M 40 3.60 x 0x01

6.2.1-A nehW eht lanoitces-ssorc epahs fo eht ehT evoba seulav fo suludom fo yticitsale ekat
yenmihc is ton ,ralucric hcus as ni emos -itlum
otni tnuocca eht cimanyd ruoivaheb fo eht
eulf ,syenmihc ti is yrassecen ot enimxe eht
.yenmihc
ytilibissop fo gnipollagc‘ ”ytilibatsni hcihw
is rehtona epyt fo serutcurts ot wind. nI all 4-A DEIFILPMIS DOHTEM
gnipollag ,snoitallicso eht edutilpma fo eht
1.4-A dniW-gnolA daoL ro Drag ecroF
esnopser seunitnoc ot esaercni htiw wind deeps
and this ,nac ,erofereht eb ylhgih .suoregnad ehT dniw-gnola daol ro gard ecrof rep tinu
ehT ecnetsixe fo gnipollag snoitallicso seod thgieh fo eht yenmihc at yna level shall eb
ton edulcerp eht roirp noitaticxe fo xetrov detaluclac morf eht noitauqe
deticxe .noitallicso ,suhT ,yllacipyt a yenmihc :
fo ralucric-non noitces-ssorc lliw tsrif og otni F, = pz. CD. dz
ecnanoser eud ot xetrov ,noitaticxe hcihw erehw
semoceb elbigilgen edistuo a small egnar fo ngised wind erusserp deniatbo ni
lacitirc wind ,deeps tuh at a llits rehgih wind pz = ecnadr;l;;; htiw SI 875 ( traP 3 ) :
,deeps gnipollag snoitallicso lliw start and eht
edutilpma fo snoitallicso eunitnoc ot esaercni
thgieh fo yna noitces fo eht yenmihc
htiw wind .deeps tI is dednemmocer that Z s
ni m derusaem morf eht pot fo
nehw syenmihc fo ralucric-non
Cross-Section noitadnuof
eht ytilibissop fo gnipollag ytilibatsni
are used, gard tneiciffeoc fo eht yenmihc ot eb
and evitneverp ,serusaem fi ,yna eb detagitsevni CD =
nekat as 8-O
yb ledom seiduts ni a wind lennut erofeb eht
retemaid fo yenmihc at thgieh z ni m
ngised is dettimmoc ot .noitucexe d, =
5