29 May 2015 - Rome Research Meeting with University of Brasilia–Brazil University of Nebraska-Lincoln (Omaha Campus) University of Rome La Sapienza StroNGER

1. franco.bontempi@uniroma1.it
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Wt ĂŶĚ ŝƚƐ ĂƉƉůŝĐĂƚŝŽŶ ƚŽ
KĨĨƐŚŽƌĞ tŝŶĚ dƵƌďŝŶĞƐ
ƌĂŶĐĞƐĐŽ WĞƚƌŝŶŝ
^ƚƌŽE'Z Ɛ͘ƌ͘ů͘
ĂĐŽůƚĂ͛ Ěŝ /ŶŐĞŐŶĞƌŝĂ ŝǀŝůĞ Ğ
/ŶĚƵƐƚƌŝĂůĞ
^ĂƉŝĞŶnjĂ hŶŝǀĞƌƐŝƚĂ͛ Ěŝ ZŽŵĂ

2. Performance-Based Wind
Engineering (PBWE) procedure
Background

3. ENVIRONMENT
Wind
actions
Structural
systems
Non
environmental
actions
EXCHANGE ZONE
Site-specific
Wind
Aerodynamic and
aeroelastic
phenomena
Wind site basic
parameters
Environmental
effects (like
waves)
Structural
system as modified
by service loads
STRUCTURAL SYSTEM
Vm
Mean wind velocity profile
Vm+ v(t)
Turbulent wind velocity profile
river
Vm
Mean wind velocity profile
Vm+ v(t)
Turbulent wind velocity profile
river
river
ENVIRONMENT EXCHANGE ZONE
Ciampoli M, Petrini F., Augusti G., (2011). “Performance-Based Wind Engineering: towards a general procedure”, Structural
Safety, 33 (6), 367-378. DOI: 10.1016/j.strusafe.2011.07.001.
Schematization of uncertainty in Wind Engineering (I)
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4. Types of uncertainties
ENVIRONMENT
Wind
actions
Structural
systems
Non
environmental
actions
EXCHANGE ZONE
1. Aleatory
2. Epistemic
3. Model
Interaction
parameters
Structural parameters
Site-specific
Wind
Aerodynamic and
aeroelastic
phenomena
Wind site basic
parameters
Intensity
measure
1. Aleatory
2. Epistemic
3. Model
1. Aleatory
2. Epistemic
3. Model
Environmental
effects (like
waves)
Structural
system as modified
by service loads
( )IM ( )IP ( )SP
STRUCTURAL SYSTEM
Ciampoli M, Petrini F., Augusti G., (2011). “Performance-Based Wind Engineering: towards a general procedure”, Structural
Safety, 33 (6), 367-378. DOI: 10.1016/j.strusafe.2011.07.001.
Schematization of uncertainty in Wind Engineering (II)
( ) ( ) ( ) ( )SPPIMPSP,IMIPPSP,IP,IMP ⋅⋅=
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5. O
f(IM|O)
f(IM) f(IP|IM,SP)
f(IP)
f(EDP|IM,IP,SP)
G(EDP)
f(DM|EDP)
G(DM)
f(DV|DM)
G(DV)
Hazard analysis
Interaction
analysis
Structuralanalysis Damageanalysis Loss analysis
IM: intensity
measure
IP: interaction
parameters
EDP:engineering
demand param.
DM:damage
measure
DV:decision
variable
Select
O, D
O:location
D:design
Environme
nt info
Decision-
making
D
f(SP|D)
f(SP)
Structural
characterization
SP:structural
system parameters
Structural
system
info
WtͲ ƌĂŵĞǁŽƌŬ
';sͿ с œ͙œ ';s|DͿ ͼ Ĩ;D|WͿ ͼ Ĩ;W|/D͕ /W͕ ^WͿ ͼ Ĩ;/W||||/D͕^WͿ ͼ
ͼ Ĩ;/DͿ ͼ Ĩ;^WͿ ͼ ĚD ͼ ĚW ͼ Ě/W ͼ Ě/D ͼ Ě^W
/ŶƚĞƌĂĐƚŝŽŶ
WĂƌĂŵĞƚĞƌƐ
^ƚƌƵĐƚƵƌĂů
WĂƌĂŵĞƚĞƌƐ
/ŶƚĞŶƐŝƚLJ
ŵĞĂƐƵƌĞ /D /W^W
ŶŐŝŶĞĞƌŝŶŐ
ĞŵĂŶĚ
WĂƌĂŵĞƚĞƌƐ
W
ĂŵĂŐĞ
DĞĂƐƵƌĞ D
ĞĐŝƐŝŽŶ
sĂƌŝĂďůĞ s
Ciampoli M., Petrini F., Augusti G., (2011). “Performance-Based Wind Engineering: towards a general
procedure”, Structural Safety, 33 (6), 367-378
';ͼͮͼͿ ŝƐ Ă ĐŽŶĚŝƚŝŽŶĂů
ĐŽŵƉůĞŵĞŶƚĂƌLJ
ĐƵŵƵůĂƚŝǀĞ ĚŝƐƚƌŝďƵƚŝŽŶ
ĨƵŶĐƚŝŽŶ
Ĩ;ͼͮͼͿ ŝƐ Ă ĐŽŶĚŝƚŝŽŶĂů
ƉƌŽďĂďŝůŝƚLJ ĚĞŶƐŝƚLJ
ĨƵŶĐƚŝŽŶ= progress with respect to the
Performance-Based Seismic Design
*
* *
Extension of the
Performance-Based
Seismic Design
procedure proposed
by PEER Research
center
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6. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 5 10 15 20 25 30 35
P(Av av*|Vm(zdeck))
Vm(zdeck)[m/s]
Ciampoli M., Petrini F., Augusti G., (2011). “Performance-Based Wind Engineering: towards a general
procedure”, Structural Safety, 33 (6), 367-378
EDP =Av - DM=max (av) [m/s2]
1.0
0.8
0.6
0.4
0.2
0
G(EDP)
0 1 2 3
WĞƌĨŽƌŵĂŶĐĞ ǀĂůƵĂƚŝŽŶ ;WсsĞƌƚŝĐĂů ĂĐĐĞůĞƌĂƚŝŽŶͿ
ƌĂŐŝůŝƚLJĐƵƌǀĞƐW;Wͮ/DͿ
ĂŝůƵƌĞƉƌŽďĂďŝůŝƚLJ';WͿ
WtͲ ƉƉůŝĐĂƚŝŽŶ ŽŶ Ă ůŽŶŐ ƐƉĂŶ ƐƵƐƉĞŶƐŝŽŶ ďƌŝĚŐĞ
Vento = f(s,t)
Vento = f(s,t)
Vento = f(s,t)
Vento = f(s,t)
WƐ
Ϭ͘Ϭ
ϳ ϭ͘ϭ
ŝĨĨĞƌĞŶƚ
ƚŚƌĞƐŚŽůĚ
ǀĂůƵĞƐ
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7. Preliminary studies:
Offshore Wind Turbines
(parked configuration)
ϭ

8. University of Notre Dame , South Bend, IN, USA
June 19, 2012 – EMI/PMC Conference
Francesco Petrini, PhD, PE
x,x’
z’
y’
Waves
Current
P
(t)vP
(t)w P
(t)uP
Turbulent
wind
P
Mean
wind
Vm(zP)
z
y
H
h
vw(z’)
Vcur(z’)
d
Terrain
ĞƐŝŐŶ ĞŶǀŝƌŽŶŵĞŶƚ ƌĞƉƌĞƐĞŶƚĂƚŝŽŶ ;ϭͿ
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9. ( ) ( ) ( ) ( )( )nfexpnSnSnS jkuuuuuu kkjjkj
−⋅=
( )( ) 2
t0
0
u
2
u u1.75)log(zarctan1.16(n)dnSı ⋅+⋅−== ∫
∞
5.0
0
uu2
x
u
200
300(x)dxR
u
1
L 





⋅== ∫
∞
z
x
z
The mean velocity magnitude varies with the
height.
MeancontributionStochasticcontribution
( )
( )[ ]5/3
ju
ju
2
V
uu
/z10,302fL1Ȧ/2ʌ
/zfL6,686ı
ȦS jj
+
=
( )j
j
zV2ʌ
Ȧz
f = ( )
( )
( ) ( )( )kj
2
kj
2
z
jk
zVzV2ʌ
zzCȦ
Ȧf
+
−
=
Autospectrum
where:
α






=
hub
hub
z
z
UzU )(
0.14=α
For normal wind condition
( )
( )
¡¡¢£
¤¤¥¦
§§¨©
−
−−
−














−=
2
5.0exp4
5
4
2
4
5
exp
2
P
P
f
ff
Pf
f
f
g
fS
σ
γ
π
α
where f=2π/T is the frequency, fP=2π/TP is the peak
frequency, α is the equilibrium coefficient, g is gravity
acceleration, ɍ and γ parameters dependent from HS e
TP






−=
−
R
yearHTS
T
FH SR
1
1
1
1max,,,
Extreme events
analysis (Return
period TR).
7
1
,)( 




 +
⋅=
d
zd
UzU refc
x
z
d
water mean level
Wind Current and waves
JONSWAP spectrum
ĞƐŝŐŶ ĞŶǀŝƌŽŶŵĞŶƚ ƌĞƉƌĞƐĞŶƚĂƚŝŽŶ ;ϮͿ
Cross-
spectrum

10.
!
#
#
$
%
'
(
)
0
1
23456786594@AB
C
DEFG
H
I
P
Q
H
R
S
T
EDP: )()( hgrhr rrm
p
σ⋅+=
)T(log2
577.0
)T(log2g
winde
winder
⋅
+⋅=
η
η
1°1°1°1°
rp
1°1°1°1°
rp
tŝŶĚ ĂŶĚ ǁĂǀĞ ĨŽƌĐĞ ƐƉĞĐƚƌĂ
U
V
W
X
Y
W
`
U
V
W
X
Y
W
a
U
V
W
X
Y
W
U
U
V
W
X
b
W
W
U
V
W
X
b
W
U
U
V
X
Y
W
c
U
V
X
Y
W
`
U
V
X
Y
W
a
U
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b
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W
d
e
f
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h
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p
q
rstuvwtstusxy€‚ƒ„…†‡ˆ
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–
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
‘
’
“
”
•
‘
–
—
^ƚƌƵĐƚƵƌĂů ƌĞƐƉŽŶƐĞ
Basis of the numerical modeling
Structural response (EDP) in frequency domain
(parked configuration)
Peak along- and across- wind displacements
Davenport’s
peak factor
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11. Previous studies: Numerical application
Uncertainties overview
(parked configuration)
Importance of SPs
as stochastic
parameters
Effects of the
interactions in the
environment
Effects of dominant
aeroelastic phenomena
1°1°1°1°
rp
1°1°1°1°
rp
EDP = peak
displacement
at the rotor

12. KE' t/E /Zd/KE
᧊᧊᧊᧊[EDP]
EDP [m]
᧊᧊᧊᧊[EDP] EDP [m]
ZK^^ t/E /Zd/KE
Comparison of mean annual frequencies ᧊[EDP] of
exceeding any value of the EDP:
Previous studies: Relevance of SP uncertainty
Risk Including SP Uncertainty (Monte Carlo 5000 samples)
Barbato M., Ciampoli M., Petrini F. (2010). “Effects of Modelling Parameter Uncertainty on the Structural Response of Offshore
Wind Turbines”, Proceedings of the 12th biennial ASCE Aerospace Division International Conference (Earth Space 2010),
Honolulu, USA, 14 – 17 March 2010. ISBN 978-0-7844-1096-7.
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13. Aerodynamic uncertainty characterization
by the meso-scale modeling
(Rotating Configuration)
Ϯ

14. Physics (1): Mean wind rotational sampling
Murtagh, P.J., Basu, B., Broderick, B.M., 2005. Along-wind response of a wind turbine tower with blade
coupling subjected to rotationally sampled wind loading. Eng. Struct. 27(8), 1209-1219
( ) ( ) ( )12 ddd zFzFF iii S
X
S
X
S
X −=∆
z1
Ω
z2
Ω
Time t2Time t1
Vm(z1)
Vm(z2)
Tributary
area
S
Ω
dFX
S
Angular
rotational
velocity
hub
( ) ( ) ( )tFFtF ii
hub
i S
X
S
X
S
X ⋅⋅∆+= ȍcosd
2
1
d
Additional peak in
the wind force
spectra
1.E-15
1.E-11
1.E-07
1.E-03
1.E+01
1.E+05
0.00001 0.001 0.1 10
Frequency [Hz]
ForceSpectraSFXFX
1
ᦸ
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15. Physics (2): Turbulent wind rotational sampling
Variation of the turbulent force spectra with the blade position
during its rotational motion
The correlation of the turbulent wind field felt by the BE is a function of its rotational motion
t+
᧓
t
Halfpenny A. (1988). Dynamic Analysis of Both On and Offshore Wind Turbines in the Frequency Domain. Ph.D. thesis.
University College London..
Connell J.R. (1988). “A PRIMER OF TURBULENCE AT THE WIND TURBINE ROTOR”, Solar Energy, 41 (3), 281-293
Auto-correlation Coherence
Ordinary wind spectra
Separation distance (is
function of the motion)

16. R
ΩΩΩΩ
Vm(r)
r
Vm(zhub)
u(r,t)
XY
Z
Aerodynamic actions by the BEM theory
Wind velocities and reference systems
- Evaluate the relative angle of attack and the relative speed of the wind with respect to specific
blade portions (BEs) at different locations
ȍÂrÂ(1+a’)
Į
Y
X
D
L
ȕ
φφφφ
VmR(r)=
Vm(r)Â(1-a)
W
Rotor
plane
u(r,t)
v(r,t)
Į’
FX= ½*ȡ*Vm
2 (cLÂcos‫+׋‬cDÂsin‫)׋‬
aerodynamicforce
referencesystem axis
wind velocity
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17. ENVIRONMENT
Structure
Non
environmental
solicitations
STRUCTURE
Structural (non-
environmental)
system
Site-specific
environment
Wind site
basic
parameters
Other
environmental
agents
Waves site
basic
parameters
Wind, wave
and current
actions
Aerodynamic
and Aeroelastic
phenomena
Hydrodynamic
phenomena
1. Aleatoric
2. Epistemic
3. Model
Types of uncertainties
1. Aleatoric
2. Epistemic
3. Model
1. Aleatoric
2. Epistemic
3. Model
Propagation Propagation
Interaction
parameters
Structural parametersIntensity
Measure
( )IM ( )IP ( )SP
EXCHANGE ZONE
/ŶƚĞƌĂĐƚŝŽŶ ƉŚĞŶŽŵĞŶĂ ŝŶ ƚŚĞ ĞŶǀŝƌŽŶŵĞŶƚ
tŝŶĚͲǁĂǀĞͲĐƵƌƌĞŶƚ ŝŶƚĞƌĂĐƚŝŽŶ
ĞŽůŝĂŶͲŚLJĚƌŽĚLJŶĂŵŝĐ ŝŶƚĞƌĂĐƚŝŽŶƐ
)10(01.0 1 mzVVcurr hourwind =⋅=
tŝŶĚ ƐƉĞĞĚͲ ǁĂǀĞ
ŚĞŝŐŚƚ ĐŽƌƌĞůĂƚŝŽŶ
Wind generated
currents
)164.00291.0221.0(
2
1
10
2
10 +⋅−⋅= VVHs
Correlation data by Zaaijer, 2006, taking into account the
Italy Waves Atlas.

18. ENVIRONMENT
Structure
Non
environmental
solicitations
STRUCTURE
Structural (non-
environmental)
system
Site-specific
environment
Wind site
basic
parameters
Other
environmental
agents
Waves site
basic
parameters
Wind, wave
and current
actions
Aerodynamic
and Aeroelastic
phenomena
Hydrodynamic
phenomena
1. Aleatoric
2. Epistemic
3. Model
Types of uncertainties
1. Aleatoric
2. Epistemic
3. Model
1. Aleatoric
2. Epistemic
3. Model
Propagation Propagation
Interaction
parameters
Structural parametersIntensity
Measure
( )IM ( )IP ( )SP
EXCHANGE ZONE
Uncertainties in Wind-Blade interactions
Vm
a, a’, cD,cL
ȍÂrÂ(1+a’)
Į
Y
X
D
L
ȕ
φφφφ
VmR(r)=
Vm(r)Â(1-a)
W
Rotor
plane
u(r,t)
v(r,t)
Į’
FX= ½*ȡ*Vm
2 (cLÂcos‫+׋‬cDÂsin‫)׋‬
ENVIRONMENT
EXCHANGE
STRUCTURE ᧁ, ᦸ
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19. 3
2
1
M3
R1
Blade-hub
main reactions
X
Y
r
FS
X
VmR(r)
u(r,t)
Numerical application
Main features of the meso-scale problem
The blade considered in this study
has a length of 38 meters and is
made of glass fiber (elastic
modulus E= 15000ᰝ106 N/m2).
™
d
e
f
g
h
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k
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m
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p
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o
n
s
p
t
u
t
t
v
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x
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z
u
{
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u
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v
w
x

€
z
u
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
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Only the along-wind turbulent component has been considered to
generate the drag and lift actions on the blade. The turbulent wind is
modeled by an eight-variate Gaussian stochastic process with the wind
acting in eight locations along the blade.
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20. 1.E-13
1.E-09
1.E-05
1.E-01
1.E+03
1.E+07
0.0 0.1 1.0 10.0
1P 2P n13P n2 n3
ForceSpectraSR1R1
[N2/Hz]
Frequency [Hz]
1.E-12
1.E-08
1.E-04
1.E+00
1.E+04
1.E+08
0.0 0.1 1.0 10.0 n [Hz]
ForceSpectraSR1R1
[N2/Hz]
1P 2Pn1 3P n2 n3
Frequency [Hz]
Evaluation of the blade stress state
PSD of the fluctuating component of the reaction R1
produced on the hub by the rotating blade - ᦸ= 16 rpm
and ᦸ= 20 rpm
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21. 10
12
14
16
18
20
22
24
25
0.00
0.01
0.02
0.03
0.04
0.05
0.33
0.4
0.5
a
ıx [m]
Uncertainties affecting the meso-level problem
Standard deviation of the blade tip displacement (᧒x) in function of
the rotating speed (ᦸ) and the induction coefficient (a)
( ) ( )
( )hubm
hubmRhubm
hV
hVhV
a
−
=
Vm(hhub): mean wind velocity at the hub
height
VmR(hhub): mean wind velocity at the hub
height and at the rotor plane
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22. Open Issues for Life-Cycle Performance
evaluation
• Identification of additional interaction
parameters (IP) determining the uncertainty
in the response (e.g. parameters modeling
aeroelasticity)
• Appropriate probabilistic characterization of
these parameters (e.g. the relevance of the
mean wind field sampling depends on the
daily hours)
• Appropriate and efficient numerical methods
to evaluate parameters of multimodal power
spectral densities (e.g. for fatigue
calculations)
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23. Analyses for investigating other
performances
ϯ

24. 1- SHIP IMPACT
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25. 1. Tipi di imbarcazione 2. Parametri caratteristici
3. Forma della prua
4. Velocità d’impatto
v § 4 - 8 nodi ĺ 2 - 4 m/s
SHIP IMPACT

26. Str
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27. MODELLAZIONE
• 580 nodi
• 555 elementi Beam188
• 40 elementi Combin14
• 1 elemento
•Mass21Str
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28. TERRENO
• Volume di terreno
modellato: cubo di
lato 80m,
discretizzato con
elementi 2x2x2 m
• 5 sottostrati in
materiale elastico
lineare con modulo
di rigidezza variabile
Elementi SOLID
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29. Ϯϵͬϭϳ
Terreno modellato
con molle lineari
lungo x e y poste a
metà dei sottostrati
Costante k variabile
con la profondità in
proporzione al
modulo E del terreno
ZŝĐĐĂƌĚŽ ^ĐŚǁĂƌnj
ŶĂůŝƐŝ Ěŝ ƐŝƚƵĂnjŝŽŶŝ ĂĐĐŝĚĞŶƚĂůŝ Ěŝ ƵƌƚŽ Ěŝ
ŶĂǀŝ ĐŽŶƚƌŽ ƚƵƌďŝŶĞ ĞŽůŝĐŚĞ ŽĨĨƐŚŽƌĞ
Molle + smorzatori
SCELTA DEI VINCOLI
WƌŽĨŽŶĚŝƚă ;ŵͿ ZŝŐŝĚĞnjnjĂ ;EͬŵͿ
ϰ ϯϲϮϳϵϬϳ
ϭϮ ϳϮϱϱϴϭϰ
ϮϬ ϭϮϬϵϯϬϮϯ
Ϯϴ ϭϵϯϰϴϴϯϳ
ϰϬ ϱϮϬϬϬϬϬϬ
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
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30. Molle + smorzatori
Dai parametri relativi al 1° e 2° modo di vibrare ricavo una stima del
coefficiente di smorzamento critico
SCELTA DEI VINCOLI
VERIFICA
• impongo uno spostamento in un punto significativo
• rilascio e monitoro l’andamento nel tempo ȟ equivalente/reale
ȟeq = 5.30 % ȟeq = 4.08%

31. 2
3
4
1
nodo 144
Dynamic behavior
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32. nodo 168
Dynamic behavior
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33. Increase of damage from the reference baseline ULS
configuration to the last equilibrium configuration
λλλλ = 1.44λλλλ = 1.00 λλλλ = 1.32λλλλ = 1.10
hůƚŝŵĂƚĞ ĐĂƉĂĐŝƚLJ ŽĨ
KĨĨƐŚŽƌĞ tŝŶĚ dƵƌďŝŶĞƐ ;KtdͿ
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34. 2 - Tower Buckling under extreme winds

35. Str
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Dimopoulos C.A., Koulatsou K., Petrini F., Gantes C.J. (2015). Assessment of Stiffening Type of the Cutout in Tubular Wind
Turbine Towers Under Artificial Dynamic Wind Actions. Journal of Computational and Nonlinear Dynamics. 10(4),041004-
041004-9.
Stiffening types of the cutout in tubular tower

36. Str
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Dimopoulos C.A., Koulatsou K., Petrini F., Gantes C.J. (2015). Assessment of Stiffening Type of the Cutout in Tubular Wind
Turbine Towers Under Artificial Dynamic Wind Actions. Journal of Computational and Nonlinear Dynamics. 10(4),041004-
041004-9.
FE model

37. Str
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Dimopoulos C.A., Koulatsou K., Petrini F., Gantes C.J. (2015). Assessment of Stiffening Type of the Cutout in Tubular Wind
Turbine Towers Under Artificial Dynamic Wind Actions. Journal of Computational and Nonlinear Dynamics. 10(4),041004-
041004-9.
Static pushover analysis

38. Str
o N
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Dimopoulos C.A., Koulatsou K., Petrini F., Gantes C.J. (2015).
Assessment of Stiffening Type of the Cutout in Tubular Wind
Turbine Towers Under Artificial Dynamic Wind Actions. Journal of
Computational and Nonlinear Dynamics. 10(4),041004-041004-9.
Incremental dynamic analysis

39. Str
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Dimopoulos C.A., Koulatsou K., Petrini F., Gantes C.J. (2015). Assessment of Stiffening Type of the Cutout in Tubular Wind
Turbine Towers Under Artificial Dynamic Wind Actions. Journal of Computational and Nonlinear Dynamics. 10(4),041004-
041004-9.
Loss of shape Vs Elephant foot buckling

40. Str
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www.stronger2012.com
Dimopoulos C.A., Koulatsou K., Petrini F., Gantes C.J. (2015). Assessment of Stiffening Type of the Cutout in Tubular Wind
Turbine Towers Under Artificial Dynamic Wind Actions. Journal of Computational and Nonlinear Dynamics. 10(4),041004-
041004-9.
Dynamic vs Static