Wind Dynamic Analysis of Structures
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Transcript of Wind Dynamic Analysis of Structures
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Wind Dynamic Analysis ofStructures
Engineering & Construction Ventures
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NATURE OF WND !OTON
DA!A"ES CAUSE DUE TO STRON" WND
D#NA!C ANA$#SS OF STRUCTURES UNDER WND
CODA$ %ROVSONS
%RACTCA$ EA!%$E
ADVANCED TO%CS
SA$ENT %ONTS
WIND DYNAMIC ANALYSIS OF STRUCTURES
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NATURE OF WND !OTON
WIND DYNAMIC ANALYSIS OF STRUCTURES
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Cyclones
It belongs to tropicl c!clones" #$ic$ %eri&e ll t$eir energ! 'ro( t$e ltent $et relese% b! t$e
con%enstion o' #ter &po)r*E+tr tropicl c!clones re pro%)ce% b! (o)ntin brriers or b!
interction o' ir (sses long 'ronts, 3- . /0 1($*
'urricane
T$e strongest #in% is clle% $)rricne 45)nr1en67, 80- . 3-- 1($,
Ty()oon
5)rricnes re 1no#n s t!p$oons Fr Est7 c!clones A)strli" In%inOcen7
Tornadoes
Most po#er')l #in%s c)sing t$e gretest %(ge, &orte+ o' ir93-- ( in %i(eter7 %e&elops
#it$in se&ere t$)n%erstor(s, (o&e 2-920 1( pre%o(inntl! to#r%s NE, ')nnel.s$pe% clo)%s,
(ini()( press)re t t$e centre o' t$e &orte+* T$)n%erstor(s: c)se% b! $e&! precipittion li1e
#ll ;ets7
NATURE OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES
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!EASURE!ENT OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES
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!EASURE!ENT OF WND * ANE!O"RA!
WIND DYNAMIC ANALYSIS OF STRUCTURES
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0. Unsteady 1a2e flo1 3Vorte4 S)edding5
6. Negati7e Aero Dynamic Dam(ing or
"allo(ing
D#NA!C EFFECTS OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES2?
Galloping is a form of aerodynamic instability caused by negative
aerodynamic damping in the cross wind direction
)U
z)(d
dCb(CU
2
! "#
2
az
+
z)d
dCb(CU
2
"#a +=
!or $ !zis positive % acts in same direction as&)d
dC(C "#
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0. Unsteady 1a2e flo1 3Vorte4 S)edding5
6. Negati7e Aero Dynamic Dam(ing or
"allo(ing
D#NA!C EFFECTS OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES3-
Cross sections prone to galloping '
uare section (zero angle of attac*)
#%shaped cross section
iced%up transmission line or guy cable
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8. Flutter
D#NA!C EFFECTS OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES38
Aero%!n(ic instbilities in&ol&ing rottion re 1no#n s @'l)tter" )sing
eron)ticl prlnce" n% re potentil proble( #it$ t$e s)spen%e%
%ec1s o' long.spn bri%ges*
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9. O7aling
D#NA!C EFFECTS OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES32
+he +ip of Chimney can e,perience radial motion with a number of
lobes around its circumference-
+his is termed as ovalling and the most common motion appears to be
two%lobed oscillation with two cycles around the periphery appearing
li*e a near ellipse at ma,imum amplitude-
Generally occurs$ when the period of circular ring coincides with the
half the period of vorte, shedding-
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D#NA!C EFFECTS OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES33
:. $oc2*in
Motion.in%)ce% 'orces cn occ)r %)ring &ibrtion pro%)ce% b! &orte+s$e%%ing
Lock-in has been observed many times %)ring t$e &ibrtion o' lig$tl!
%(pe% c!lin%ricl str)ct)res s)c$ s steel c$i(ne!s" n% occsionll!
%)ring t$e &orte+.in%)ce% &ibrtion o' long.spn bri%ges*
T$e 'reB)enc! o' t$e s$e%%ing o' &ortices cn @loc1.in to t$e 'reB)enc! o'
(otion o' t$e bo%!*
T$e strengt$ o' t$e &ortices s$e%" n% t$e 'l)ct)ting 'orces res)lting relso en$nce%*
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Cross.#in% response o' slen%er to#ers
Sin)soi%l e+cittion (o%el :
EB)tion o' (otion ;t$ (o%e7:
;7 is (o%e s$pe
)(tQaKaCaG jjjj =++
;is t$e @generlie% or e''ecti&e (ss h
&
2
. dz(z)m(z)
;t7 is t$e @generlie% or e''ecti&e 'orce h
& . dz(z)t)f(z$
D#NA!C ANA$#SS OF STRUCTURES UNDER WND
WIND DYNAMIC ANALYSIS OF STRUCTURES3/
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Representing t$e pplie% 'orce ;t7 s sin)soi%l ')nction o' ti(e" n
e+pression 'or t$e pe1 %e'lection t t$e top o' t$e str)ct)re cn be
%eri&e% :
==
h
&
2
.
2
h
& .
2
..
2
h
& .
2
ama,
dz(z)tc/0
dz(z)C
t1G0
dz(z)bC
b
(h)y
#$ere ;is t$e criticl %(ping rtio 'or t$e ;t$ (o%e" eB)l to jjj
KG
C
2
)(zU
bn
)(zU
bnt
e
.
e
s ==
2
a
.
b
m1/c
=
Scr)ton N)(ber or (ss.%(ping pr(eter7( &erge (ss)nit$eig$t
Stro)$l N)(ber 'or &orte+ s$e%%ing e e''ecti&e $eig$t 2$37
D#NA!C EFFECTS OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES30
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T$is cn be si(pli'ie% to :
For )ni'or( or ner.)ni'or( cntile&ers" cn be t1en s 8*0,t$en 1 8*
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Rn%o( e+cittion (o%el Gic1er!Hs)7
Ass)(es e+cittion %)e to &orte+ s$e%%ing is rn%o( process
A non %i(ensionl pr(eter constnt 'or prtic)lr str)ct)re
'orcing ter(s7
In its si(plest 'or(" pe1 response cn be #ritten s :
e1 response is in&ersel! proportionl to t$e square root of the
%(ping
22
2
)3()/45(
6
/
L
aoy
yKSc
Aby
=
@loc1.in be$&io)r is repro%)ce% b! negti&e ero%!n(ic %(ping
!L li(iting (plit)%e o' &ibrtion
Jo non %i(ensionl pr(eter ssocite% #it$ ero%!n(ic%(ping
D#NA!C EFFECTS OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES3=
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WIND DYNAMIC ANALYSIS OF STRUCTURES
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Rn%o( e+cittion (o%el Gic1er!Hs)7
T$ree responseregi(es :
Loc1 in region . response%ri&en b! ero%!n(ic
%(ping
@Loc1.in
Regi(e
@Trnsition
Regi(e
@Force%
&ibrtion
Regi(e2 0 8- 2-
-*8-
-*-8
-*--8
Scr)ton
N)(ber
M+i()( tip
%e'lection
%i(eter
D#NA!C EFFECTS OF WND
WIND DYNAMIC ANALYSIS OF STRUCTURES3?
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T$e Scr)ton N)(ber or (ss.%(ping pr(eter7 ppers in pe1
response clc)lte% b! bot$ t$e sin)soi%l n% rn%o( e+cittion(o%els
So(eti(es (ss.%(ping pr(eter is )se% Sc /
2
ab
m1/c
=
2
ab
m1
Sc or J7 re o'ten )se% to in%icte t$e propensit! to
&orte+.in%)ce% &ibrtion
Clerl! t$e lo#er t$e Sc" t$e $ig$er t$e &l)e o' !(+ b eit$er
(o%el7
WIND DYNAMIC ANALYSIS OF STRUCTURES/-
TOWERS; C'!NE#S AND !ASTS * SCRUTON NU!,ER
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Sc or J7 is o'ten )se% to in%icte t$e propensit! to &orte+.in%)ce%
&ibrtion
e*g* 'or circ)lr c!lin%er" Sc K 8- or JK -*>7" )s)ll! in%ictes lo#(plit)%es o' &ibrtion in%)ce% b! &orte+ s$e%%ing 'or circ)lr
c!lin%ers
A(ericn Ntionl Stn%r% on Steel Stc1s ASME STS.8.8??27
pro&i%es criteri 'or c$ec1ing 'or &orte+.in%)ce% &ibrtions" bse% on
J
A (et$o% bse% on t$e rn%o( e+cittion (o%el is lso pro&i%e% in
ASME STS.8.8??2 Appen%i+ 0*C7 'or clc)ltion o' %isplce(ents'or %esign p)rposes*
Mitigtion (et$o%s re lso %isc)sse% : $elicl str1es" s$ro)%s"
%%itionl %(ping (ss %(pers" 'bric p%s" $nging c$ins7
WIND DYNAMIC ANALYSIS OF STRUCTURES/8
SCRUTON NU!,ER AND STEE$ STAC
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For (itigtion o' &orte+.s$e%%ing in%)ce% &ibrtion :
Eli(intes cross.#in% &ibrtion" b)t increses
%rg coe''icient n% long.#in% &ibrtion
$3
$-*8b
b
WIND DYNAMIC ANALYSIS OF STRUCTURES/2
TOWERS; C'!NE#S AND !ASTS * 'E$CA$ STRA
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Slen%er str)ct)res $eig$t#i%t$ is $ig$7
Mo%e s$pe in 'irst (o%e . non liner
5ig$er resonnt (o%es (! be signi'icnt
Cross.#in% response signi'icnt 'or circ)lr cross.sections
criticl &elocit! 'or &orte+ s$e%%ing 0n8b 'or circ)lr sections
8- n8b 'or sB)re sections
. (ore 'reB)entl! occ)rring #in% spee%s t$n 'or sB)re sections
WIND DYNAMIC ANALYSIS OF STRUCTURES/3
TOWERS" C5IMNEYS AND MASTS
GUST EFFECTIVE FACTOR METHOD ALONG WIND EFFECT
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GUST EFFECTIVE FACTOR METHOD ALONG WIND EFFECT
Hc1ro)n% Fctor
As per IS 875 - 1993
)st Fctor
)st Energ! Fctor
Sie Re%)ction
Fctor
D(ping
Ro)g$ness
Fctor
WIND DYNAMIC ANALYSIS OF STRUCTURES//
ACROSS WIND EFFECT VORTE! SHEDDING"
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ACROSS WIND EFFECT VORTE! SHEDDING"
WIND DYNAMIC ANALYSIS OF STRUCTURES/0
ALON WIND RESONSE UST RESONSE FACTOR
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T$e g)st response 'ctors 'or bse b*(* n% tip %e'lection
%i''er . bec)se o' non.liner (o%e s$pe
S$er 'orce : (+ * B
Hen%ing (o(ent : M(+ M* (
De'lection : +(+ +* +
T$e g)st response 'ctors 'or b*(* n% s$er %epen% on t$e
$eig$t o' t$e lo% e''ect" 8i*e* B87 n% (87 increse #it$ 8
WIND DYNAMIC ANALYSIS OF STRUCTURES/ 22-; @
Win% in P Direction
Li(iting : $3-- =
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Win% in P Direction
=8
DEF$ECTON UNDER D#NA!C WND $OAD
r-7o-
#irection U,(mm)
Uy(mm)
Uz
(mm)
() 8ind %9: @-< -&? ?
(2) 8ind % %: @/ 2 2=
( 2/ 2< 2& 2/-2 2 2&-2
CASE STUD# K STATC CASE
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r-7o-
#irection Aasehear(*7)
() 8ind %9: 2;/&
(2) 8ind % %: 2@
CASE STUD# K !ACAU TOWER
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Concrete to#er 2/> (etres >8/
'eet7 $ig$ Tpere% c!lin%ricl
section )p to 2-- (
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CASE STUD# B !ACAU TOWER
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MACAU TOWER0.5% damping
.0--
-
0--8---
80--
2---
- 2- /- - 8--
Full scale mean 1ind s(eed at /8Hm 3m>s5
R*(*s* MenM+i()( Mini()(
Win% t)nnel test res)lts . long.#in% b*(* MN*(7 t >0*0 ( 2>- 't*7
WIND DYNAMIC ANALYSIS OF STRUCTURES>8
CASE STUD# B !ACAU TOWER
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MACAU TOWER
0.5% damping
.2---
.80--
.8---
.0--
-
0--
8---
80--
2---
- 2- /- - 8--
Full scale mean 1ind s(eed at /8Hm 3m>s5
R*(*s* Men
M+i()( Mini()(
Win% t)nnel test res)lts . cross.#in% b*(*MN*(7 t >0*0 ( 2>-
't*7
WIND DYNAMIC ANALYSIS OF STRUCTURES>2
CASE STUD# * A$ON" WND RES%ONSE
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At eac) le7el on t)e structure define eui7alent 1ind loads
for B
(en #in% press)re
bc1gro)n% B)si.sttic7 'l)ct)ting #in% press)re
resonnt inertil7 lo%s
T)ese com(onents all )a7e different distriutions
Com(uter model calirated against 1ind*tunnel results
Comine t)ree com(onents of load distriutions for
ending moments at 7arious le7els on to1er
WIND DYNAMIC ANALYSIS OF STRUCTURES>3
CASE STUD# B !ACAU TOWER
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!acau To1er Effecti7e static loads
3sGH m5
U meanG 8@ :m>sM 8J dam(ing
-
0-
8--
80-2--
20-
3--
30-
- 8-- 2--
$oad 32N>m5
'eig)t3m5
Men
Hc1gro)n%
Resonnt
Co(bine%
WIND DYNAMIC ANALYSIS OF STRUCTURES>/
CASE STUD# B !ACAU TOWER
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MACAU TOWER - Turbulence
Intensit !r"#le
-
0-
8--
80-
2--
20-
3--
30-
-*- -*8 -*2 -*3
Iu
Full*scale
'eig
)t3m5
Win%.t)nnelAS88=-*2Mc) H)il%ing Co%e
T)rb)lence intensit! pro'ile :
WIND DYNAMIC ANALYSIS OF STRUCTURES>0
CASE STUD# B !ACAU TOWER
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Along*1ind res(onse 1as dominant
Cross*1ind 7orte4 s)edding e4citation not strong ecause
of com(le4 (od geometry near t)e to(
Along* and cross*1ind )a7e similar fluctuating com(onents
aout eual; ut total along*1ind res(onse includes mean
com(onent
WIND DYNAMIC ANALYSIS OF STRUCTURES>