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1. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Sapienza – University of Rome
Francesco Petrini, Ph.D., P.E.
Konstantinos Gkoumas, Ph.D., P.E.
Franco Bontempi, Ph.D., P.E.
Sapienza - University of Rome
Dipartimento di Ingegneria Strutturale e
Geotecnica
Recent developments and uncertainty aspects in the
performance based design of structures for wind
2. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Presentation outline
2
• Overview of the Performance Based Wind
Engineering (PBWE) procedure
• Models for tall buildings and the assessment of
occupant comfort:
• Application on a high-rise building
• Assessment of the annual probabilities of exceeding
the human perception thresholds
• Vibration and occupant comfort issues
• Damage analysis
• Loss analysis
• Conclusions and indications for further research
3. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Presentation outline
3
• Overview of the Performance Based Wind
Engineering (PBWE) procedure
• Models for tall buildings and the assessment of
occupant comfort
• Application on a high-rise building
• Assessment of the annual probabilities of exceeding
the human perception thresholds
• Vibration and occupant comfort issues
• Damage analysis
• Loss analysis
• Conclusions and indications for further research
4. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Performance-Based Wind Engineering (PBWE)
Uncertainties in wind engineering
4
ENVIRONMENT
Wind
actions
Structural
systems
Non
environmental
actions
EXCHANGE ZONE
Site-specific
Wind
Aerodynamic
and aeroelastic
phenomenaWind site
basic
parameters
Environmental
effects (like
waves)
Structural
system as modified
by service loads
STRUCTURAL SYSTEM
Ciampoli M, Petrini, F. & Augusti G., 2011, Performance-Based Wind Engineering: toward a general procedure,
Structural Safety, Structural Safety, 33(6), 367-378.
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
5. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
5
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
phenomenaWind 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
( ) ( ) ( ) ( )SPPIMPSP,IMIPPSP,IP,IMP ⋅⋅=
Performance-Based Wind Engineering (PBWE)
Uncertainties in wind engineering
6. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Performance-Based Wind Engineering (PBWE)
6
The problem of risk assessment is disaggregated into the following elements:
- site and structure-specific hazard analyses, that is, the assessment of the
probability density functions f(IM), f(SP) and f(IP|IM,SP);
- structural analysis, aiming at the assessment of the probability density function of
the structural response f(EDP|IM,IP,SP) conditional on the parameters characterizing the
environmental actions, the wind-fluid-structure interaction and the structural properties;
- damage analysis, that gives the damage probability density function f(DM|EDP)
conditional on EDP;
- finally, loss analysis, that is the assessment of G(DV|DM), where G(·|·) is a
conditional complementary cumulative distribution function.
G(DV) = ∫…∫ G(DV|DM) · f(DM|EDP) · f(EDP|IM, IP,SP) · f(IP|IM,SP) ·
· f(IM) · f(SP) · dDM · dEDP · dIP · dIM · dSP
Interaction
Parameters
Structural
Parameters
Intensity
measure
IM IP SP
Engineering
Demand
Parameters
EDP
Damage
Measure
DM
Decision
Variable
DV
7. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
PBWE procedure flowchart
7
Petrini, F. & Ciampoli M., 2012, Performance-based wind design of tall buildings, Structure & Infrastructure
Engineering, 8(10), 954-966.
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
Ciampoli M, Petrini, F. & Augusti G., 2011, Performance-Based Wind Engineering: toward a general
procedure, Structural Safety, Structural Safety, 33(6), 367-378.
8. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
8
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
Aerodynamic
analysis
Struc’l analysis Damage analysis Loss analysis
IM: intensity measure
IP: interaction
parameters
EDP: engineering
demand parameters
DM: damage measures DV: decision variables
Select
O, D
O: location
D: design
Environment
info
Decision-
making
D
f(SP|D)
f(SP)
Structural
characterization
SP: structural system
parameters
Structural
system info
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
Aerodynamic
analysis
Struc’l analysis Damage analysis Loss analysis
IM: intensity measure
IP: interaction
parameters
EDP: engineering
demand parameters
DM: damage measures DV: decision variables
Select
O, D
O: location
D: design
Environment
info
Decision-
making
D
f(SP|D)
f(SP)
Structural
characterization
SP: structural system
parameters
Structural
system info
O, D
g(IM|O,D)
g(IM)
p(EDP|IM)
P(EDP)
p(DM|EDP)
P(DM)
p(DV|DM)
P(DV)
Hazard analysis Struc’l analysis Damage analysis Loss analysis
IM: intensity
measure
EDP: engineering
demand param.
DM: damage
measure
DV: decision
variable
Select
O, D
O: location
D: design
Facility
info
Decision-
making
O, D
g(IM|O,D)
g(IM)
p(EDP|IM)
P(EDP)
p(DM|EDP)
P(DM)
p(DV|DM)
P(DV)
Hazard analysis Struc’l analysis Damage analysis Loss analysis
IM: intensity
measure
EDP: engineering
demand param.
DM: damage
measure
DV: decision
variable
Select
O, D
O: location
D: design
Facility
info
Decision-
making
PBWEPBEE
9. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Presentation outline
9
• Overview of the Performance Based Wind
Engineering (PBWE) procedure.
• Models for tall buildings and the assessment of
occupant comfort
• Application on a high-rise building
• Assessment of the annual probabilities of exceeding
the human perception thresholds
• Vibration and occupant comfort issues
• Damage analysis
• Loss analysis
• Conclusions and indications for further research
10. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
10
Tamura,Y.(2009).Windandtallbuildings,ProceedingsoftheFifth
European&AfricanConferenceonWindEngineering(EACWE5),
Florence,Italy,July19-23,2009..
Vibration frequency
Accelerationthresholdsformotion
perception
w(t;z2)Vm(z2)
Vm (z1)
Vm (z3)
V(t;z2)
v(t;z2)u(t;z2)
X
Z
Y
θ
B1
B2
H
Loss of serviceability
Lossofintegrityof
non-structural
elements
Motionperception
bybuilding
occupants
Displacements
Acceleration
Discomfort level in terms of
perception thresholds
1
11. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
11
Loss of serviceability
Lossofintegrityof
non-structural
elements
Motionperception
bybuilding
occupants
Bashor,R.andKareem,A.(2007)."ProbabilisticPerformanceEvaluationof
Buildings:AnOccupantComfortPerspective",Proc.12thInternational
ConferenceonWindEngineering,1-6July,Cairns,Australia.Available
onlineathttp://www.nd.edu/~nathaz/[Accessed15June2010].
w(t;z2)Vm(z2)
Vm (z1)
Vm (z3)
V(t;z2)
v(t;z2)u(t;z2)
X
Z
Y
θ
B1
B2
H
Discomfort level in terms of
perception thresholds
Usually Across wind vibration
is critical for comfort
The reference period for
comfort evaluation is 1 year
1
2
3 1st
natural frequency is dominant4
Italian Guidelines
f1
Scalarthreshold
Displacements
Acceleration
12. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
12
Case study structure
Structure
•74 floors
•Height H=305m
•Footprint B1=B2=50m (square)
3dframeontheexternalperimeter
centralcore
Bracing system
A steel high-rise building
Finite Element model
B1
B2
H
FE Model
Approximately
•10,000 elements
•4,000 nodes
•24,000 DOFs
13. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
13
Experimental model of
Actions
SpenceS.M.J.,GioffrèM.,GusellaV.,Influenceofhighermodesonthe
dynamicre-sponseofirregularandregulartallbuildings,Proc.6th
InternationalColloquiumonBluffBodiesAerodynamicsand
Applications(BBAAVI),Milano,Italy,July20-24,2008.
Boundary Layer Wind Tunnel of the
CRIACIV in Prato, Italy
1:500Scalemodel
Response
time history
Time domain structural analyses
(Experimental actions)
Time domain
analyses
Experimental
forces
-30
-20
-10
0
10
20
30
3500 3600 3700 3800 3900 4000
aL, aD
[cm/s2
]
t [s]Along Across
14. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
14
( )
( )
( ) )(),(
),,(exp
1
),(),(
22
212
2
ωχωρ
ωξξ
ωρω
⋅⋅⋅⋅=
=⋅⋅−⋅
⋅⋅⋅⋅=
∫∫
hSVc
dAdAf
A
hSVchS
uumxD
A A
uumxDDD tt
( )
)(),h(S
)(HVc
),h(S)(H),h(S
2
uu
22
mxD
DD
2
rr tttt
ωχω
ωρ
ωωω
⋅⋅
⋅⋅⋅⋅
=⋅=
⋅+
−
⋅
⋅
⋅
=
2
0
2
2
2
0
2
2
0
2
2
41
1
1
)(
ω
ω
ν
ω
ω
ω
ω
m
H
rrm
p
grr σ⋅+= rg
Wind action
spectra
(analytical)
Response spectra
Peak response
Frequency domain response
Response Peak
Factor
Analytical model of the buffeting forces
( ) ( ) ( ) ( )( )ωfexpωSωSωS jkuuuuuu kkjjkj
−=
( )
( )
( ) ( )( )kj
2
kj
2
z
jk
zVzV2π
zzCω
ωf
+
−
=
Cross-spectrum
5.0
0
uu2
x
u
200
300(x)dxR
u
1
L
⋅== ∫
∞
z
where:
( )
( ) [ ]5/3
ju
ju
x2
u
uu
/zLf10.3021ω/2π
/zLfσ6.686
ωS jj
⋅⋅+⋅
⋅⋅⋅
=
( )( ) 2
fri0
0
u
2
u
u1.75)log(zarctan1.16
(n)dnSσ
⋅+⋅−=
== ∫
∞
)z(V2π
zω
f
jm
j
⋅
⋅
=
Autospectrum
( ) 3ew(t)2ev(t)1eu(t))j(zmV)jz(t;jV
⋅+⋅+⋅+=
α
10m
10
z
V(z)V
⋅=
Solari,G.Piccardo,G.(2001).Probabilistic3-Dturbulencemodelingforgustbuffetingof
structures,ProbabilisticEngineeringMechanics,(16),73–86.
Turbulentwindvelocityspectra
(analytical)
Model of the Vortex shedding forces
(variable with the angle of attack)
1.E+01
1.E+03
1.E+05
1.E+07
1.E+09
1.E+11
0.000 0.001 0.010 0.100 1.000
PSD
n [Hz]
Total Forcespectrum
Turbulenceforcespectrum
Vortexsheddingforcespectrum
17. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
17
Hazard analysis
( ) ( )
θ
−⋅
θ
⋅
θ
θ
=θ
θ−θ
θ
)(
10
1)(
10
10, exp
)(
)(
),(f 10
kk
V
c
V
c
V
c
k
V
The roughness length z0 is characterized by a
lognormal PDF. The mean value μz0 and the
standard deviation σz0 of z0 are expressed as
function of θ (assuming a slight difference between
four sectors, i.e. a mean value of z0 varying
between 0.08 m and 0.12 m and a COVz0 equal to
0.30).
V10 and θ are described by their joint probability
distribution function
θ
V10
IM =
θ
V10
z0
Parameters c(θ) and k(θ) are derived from NIST®
wind speed database.
(Annual occurrence)
Models for tall buildings and the assessment of occupant comfort
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
Structural analysis 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
18. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
18
Models for tall buildings and the assessment of occupant comfort
Interaction analysis IP =
gr
CD
CL
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
Structural analysis 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
19. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
19
Interaction analysis IP =
gr
CD
CL
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
Structural analysis 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
Models for tall buildings and the assessment of occupant comfort
462.2507.1265.0 2
+ξ+ξ−=µ
rg
( )
≤⋅η
>⋅η
⋅η+
−
⋅η
=σ
+
+
+
+
122if650
122if
46
213
45
2
21
.T.
.T
.
)Tln(
.
)Tln(
.
windr,e
windr,e
windr,e
windr,e
gr
( )
<≤
η
<≤
η−
=η +
+
+
1690if
690100if
380631 450
r
r
r
r
.
r
r,e
q.
.q.
.q.
r
r
r σ
σ
=+η
(Obtained from time-domain
analyses)
The peak response factor gr is characterized by a Gaussian distribution function
rgµ
rgµ
Vanmarcke (1975)
The aerodynamic coefficients CD and CL are characterized by Gaussian
distributions. Mean values are expressed as a function of θ, varying from
those corresponding to a square shape (for θ = 0) to those corresponding to
a rhomboidal shape (for θ = 45); the coefficient of variations of CL and CD
are taken equal to 0.07 and 0.05.
μCD μCL
D
Cµ
μCD μCL
L
Cµ
rrm
p
grr σ⋅+=
20. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
20
EDP = aL
p
G(EDP) = ∫…∫ G(EDP|IM, IP, SP) · f(IP|IM,SP) · f(IM) · f(SP) · dIP · dIM · dSP
Monte Carlo sim
(5000 runs)
aL
p
Reduced
formulation
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
Structural analysis 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
Structural analysis
Models for tall buildings and the assessment of occupant comfort
21. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
21
Risk Curve. EDP= aL
p
= peak acceleration in the across wind direction
The annual probabilities of exceeding the human perception thresholds for
apartment and office building vibrations are 0.0576 and 0.0148 respectively.
aL
p
G(aL
p)
aL
p [mm/s2]
Ciampoli, M. & Petrini, F., 2012, Performance-Based Aeolian Risk assessment and reduction for tall buildings, Probabilistic
Engineering Mechanics, 28 (75–84).
Models for tall buildings and the assessment of occupant comfort
22. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
22
TMD
Design Parameters
γ = mTMD/mtot
β = ωTMD/ ω1
ξ* = damping of TMD
aL
p[mm/s2]
n [Hz]
β = ξ* =
β = ξ* =
β = ξ* =
β = ξ* =
β = ξ* =
β = ξ* =
β = ξ* =
G(aL
p)
aL
p [mm/s2]
Parametric analysis Effects on risk
γ = 1/150
Aeolian Risk reduction using TMD
Models for tall buildings and the assessment of occupant comfort
23. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Presentation outline
23
• Overview of the Performance Based Wind
Engineering (PBWE) procedure.
• Models for tall buildings and the assessment of
occupant comfort
• Application on a high-rise building
• Assessment of the annual probabilities of exceeding
the human perception thresholds
• Vibration and occupant comfort issues
• Damage analysis
• Loss analysis
• Conclusions and indications for further research
24. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
24
Vibration and occupant comfort issues
Consequences of wind induced vibrations
in high rise buildings
-Fear and alarm
-Discomfort
-Reduced task concentration
-Dizziness, migraine and nausea
Kwok, K.C.S., Hitchcock, P.A. & Burton, M.D., 2009, Perception of vibration and occupant comfort in wind-
excited tall buildings, Journal of Wind Engineering and Industrial Aerodynamics, 97(7-8), 368-380
Wind induced vibration
−Damage analysis
−Loss Analysis
Studies on human perception of vibration and tolerance thresholds
-Field experiments and studies in wind-excited buildings
-Motion simulator tests
-Field experiments conducted in artificially excited buildings
Mitigation measures
-Modifications to the structural system and/or the
aerodynamic shape
-Installation of vibration control devices
- Negative impressions/ publicity
- Eventually they can be an attraction
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
Structural analysis 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
25. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
25
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
Structural analysis 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
Damage analysis
Probabilistic damage analysis: assign a probability distribution to the perception
thresholds
Procedure: obtain a pdf that assigns at each vibration level a percentage of persons
that experience discomfort
Kwok, K.C.S., Hitchcock, P.A., 2008. Occupant comfort test using a tall building motion simulator. In: Proceedings of Fourth
International Conference on Advances in Wind and Structures, Jeju, Korea, 28–30 May.
Vibration and occupant comfort issues
26. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
26
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
Structural analysis 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
Loss analysis
Probabilistic loss analysis: assign a cost probability for different damages
Issues: the uncertainty in the cost relies on various factors (e.g. market trend)
DM
Non structural elements
Structural elements
Comfort
Safety
Serviceability
Safety
Serviceability
DV
Direct
Indirect
(As a direct damage to the structure)
(As a consequence of the damaged structure)
IM
SP
IP EDP DM DV
- Direct VS indirect cost that are not
possible to account for in monetary terms.
- Initial VS life-cycle cost. In particular
regarding the evaluation of retrofitting
strategies that could improve the
serviceability performance (e.g. comfort),
by means of vibration mitigation.
Vibration and occupant comfort issues
27. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Presentation outline
27
• Overview of the Performance Based Wind
Engineering (PBWE) procedure.
• Models for tall buildings and the assessment of
occupant comfort
• Application on a high-rise building
• Assessment of the annual probabilities of exceeding
the human perception thresholds
• Vibration and occupant comfort issues
• Damage analysis
• Loss analysis
• Conclusions and indications for further research
28. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
• Occupant comfort is an important issue in the design of
tall buildings. Due to the stochastic nature of wind action
and wind-induced vibration, deterministic analyses are
inadequate for carrying out a comfort assessment.
• The insertion of passive control devices can reduce
the vibration perception of building occupants. But the
effectiveness of the device must be evaluated in terms of
cost (by computing the probability of exceeding
acceptable values of an appropriate DV).
• Damage and loss analysis of wind-induced vibrations
will be based on corroborated literature studies that
provide statistics on the occupant comfort.
28
Conclusions and indications for further research
29. Recentdevelopmentsanduncertaintyaspectsintheperformancebaseddesignofstructuresforwind
COMPDYN 2013
4th International Conference on Computational Methods in Structural Dynamics
and Earthquake Engineering, 12-14 June, Kos, Greece
Francesco Petrini
Konstantinos Gkoumas
Franco Bontempi
Thank you for your attention
29
Francesco Petrini, Konstantinos Gkoumas, Franco Bontempi
Sapienza - University of Rome, Dipartimento di Ingegneria Strutturale e Geotecnica
Acknowledgements:
Prof. Marcello Ciampoli, Prof. Giuliano Augusti
This study is partially supported by StroNGER s.r.l. from the fund “FILAS - POR FESR LAZIO
2007/2013 - Support for the research spin-off”.
Editor's Notes
- First, I will provide an overview of the PBWE procedure, as it has been defined in several studies and journal papers by my co-author Dr. Petrini In the second part of my presentation I will briefly discuss models for the occupant comfort assessment in high-rise buildings Finally, I will introduce some considerations for the extension of the application of the PBWE framework to the Damage and Loss analysis from vibration discomfort in high-rise buildings. This is a work in process by me with my co-authors.
Under the PBWE framework, a classification of different sources of uncertainty in wind engineering problems has been proposed. Three different physical regions are identified according to their location relatively to the structure: the environment (region of unperturbed wind field) characterized by some basic uncertain parameters ( wind mean velocity and direction , wave height, etc.), the structural system , characterized by some structural uncertain parameters ( geometry, stiffness, mass , etc.), and the so called “ exchange zone ” , that is the region around the structure where the wind field is strongly influenced by the presence of the structure and the effects of the interaction between the relevant properties of both the structure and the wind field cannot be disregarded; the exchange zone is characterized by proper uncertain interaction parameters ( aerodynamic coefficients , aerodynamic damping , etc.).
By definition, the uncertainty of the basic and structural parameters must be taken into account in characterizing the wind-structure interaction phenomena of the exchange zone, while the uncertainty of the relevant parameters in the exchange zone has no influence on the basic and structural parameters. This classification suggests formal representation of the propagation expressed in terms of conditional probabilities .
The structural risk is conventionally measured by the probability of exceeding a relevant value of the corresponding DV . A simplification is introduced: If the performance is expressed by the fulfillment of a limit state , and the limit state condition in terms of an EDP , the whole procedure can be simplified assuming DV = EDP .
The assessment of the serviceability of high-rise buildings under wind actions is usually carried out considering the peak values of the horizontal displacements, some measure of the acceleration . Horizontal displacements shall be limited to prevent loss of integrity to cladding and partitions ; the acceleration measure and the building natural frequencies are essential to determine the level of perception of motion , and in general the habitability issue under building vibrations. the occupant motion perception can be related to body sensation and/or visual cues; in general, the perception related to body sensation is dominant in case of low frequency vibrations (less than 2 Hz) , while the perception related to visual cues is dominant in case of relatively high frequency vibrations (greater than 2 Hz). In the right figure from Tamura ed al, comfort curves are shown (ISO and Japanese) Percentage of people that experience discomfort, confronted with literature (at any given frequency corresponds a perception threshold) Figura Tamura, curve di comfort, percezione da giaponesi e ISO Fa vedere I risultati (percentualle di persone che sentono discomfort), confrontate con letteratura, a seconda della frequenza ce soglia di percezione
The Italian code adopts the Japanese curves. What you do is enter the graph with the first natural frequency of the structure and see the acceptance rate of the accelerations. La norma italiana percepisce le curve giaponesi, entri con f1 (prima frequenza), e vedi il limite di accettabilita delle accelerazioni
The examined high-rise steel building has a square plan (side length: B = 50 m) and a total height of 305 m; the number of floors is 74. The main structural system is composed by a central core (a 3D frame with 16 columns) and a 3D frame on the external perimeter (28 columns). The two substructures are connected at three levels (at the height of 100 m, 200 m and 300 m); the stiffening systems are extended for 3 or 2 floors . The structural analyses have been carried out on a FE model of the building implemented in ANSYS V11; the FE model is composed by 7592 BEAM4 elements and 2680 LINK8 elements Linear dynamic analyses , assuming rigid diaphragms
Forse togliere The time series of the floor forces have been obtained by wind tunnel tests on a 1:500 scale rigid model (Fig. left ), that have been carried out at the Boundary Layer Wind Tunnel of the CRIACIV (Inter-university Research Centre on Buildings Aerodynamics and Wind Engineering) in Prato, Italy. One the other hand, well consolidated analytical models has been adopted in order to carry out structural analyses in frequency domain Left: Floor forces in the along and across wind direction, evaluated at the top of the building, by scaling the experimental measures Right: Acceleration at the top of the building for a mean wind velocity at the top of the building for a V=35 m/sec (DESIGN RETURN PERIOD OF 1 YEAR according to the ITALIAN CODE/CNR 2008) – V0=20.25 m/sec
In this slide you can see the analytical model of the buffeting forces and the Vortex Shedding model . In particular, the VS effect is strong when the wind is orthogonal to the building side. The VS energy is higher. La frequenza di VS ha piu’ energia delle altre Rosso: turbolenza normale Nero VS ipotizzato tarato Blu: totle sovraposizione dei due For the examined building, time series of the floor forces were available , as derived by experimental tests (Spence et al 2008a, 2008b). However, in order to carry out probabilistic calculations, in the linear range it is preferable (at least, to reduce the computational burden) to analyze the structural response in the frequency domain , by adopting the previously introduced analytical model of the wind action.
Blu: torque Red: forces in the x and y axis
The time series of the floor forces have been obtained by wind tunnel tests on a 1:500 scale rigid model (Fig. 2), that have been carried out at the Boundary Layer Wind Tunnel of the CRIACIV (Inter-university Research Centre on Buildings Aerodynamics and Wind Engineering) in Prato, Italy. One the other hand, well consolidated analytical models has been adopted in order to carry out structural analyses in frequency domain
The analysis steps are as follows: First hazard analysis: The intensity measure vector contains the following random elements V10 (10 minute velocity) Theta (the direction of the wind velocity) Z0 (roughness length) Joint Probability Density Function of the MEAN VELOCITY Finally, all previously introduced parameters has been considered random. Here the structural response in terms of across wind peak accelerations is still represented as function of the V10. I passi dell’analisi Distribuzione V10 di cui parametri dipendono da theta Dal database di NIST, Dal mare coef rug basso Z0 dipende da theta
Secondo passo,… parametri scelti: coefficiente di picco e 2 aerodinamici
Riassunto Edp accelerazione di picco across wind
Figure Complementary cumulative function of the EDP
Metto TMD tre parametri beta rapporto di frequenze Analisi parametrica variando I 3 rapporti per scegliere Risultati per gamma fissato, alvariare di beta… risposte massime Basso a destra come cambia la curva di rischio In order to optimize the structural response, the insertion of a TMD can be considered. Here the TMD has been inserted at the top of the building and the structural response is represented in terms of occupant comfort. The TMD produces two main effects: the variation of the structural natural frequency, and a reduction in maximum the response. Here the maximum across wind acceleration obtained for different sets of TMD design parameters are shown and compared with the comfort thresholds. Each figure represents a different mass ratio “gamma”, different markers represent different natural frequency ratios “beta” and different points with the same marker represent different damping ratios “csi”. The maximum effect is obtained by “gamma” equal to 1/150, “Beta” equal to 1 and “csi” equal to 10%
In this part I will provide some considerations for the application of the PBWE framework to the Damage and Loss analysis due to the occupant discomfort in high-rise buildings
So far, the research focused on the Hazard, Interaction and Structural analysis for the occupant comfort. In order to apply the PBWE framework to the damage and loss analysis from vibration comfort, some additional considerations are necessary. In this slide are reassumed the major issues (from a paper by Kwok et al) Mitigation measures in particular are proposed in literature in the form of among else the installation of vibration control devices
Left Distribution of comfort ratings from occupant comfort tests conducted in motion simulator Right Comparison of occupant comfort serviceability criteria for 1 year return period wind storm . The uncertainty can be modeled considering the different density of the lines at different frequencies.
