Compdyn kg

Recent developm

ents and uncertainty aspects in the performance based design of structures for w

ind

COMPDYN 20134th International Conference on Computational Methods in Structural Dynamicsand Earthquake Engineering, 12-14 June, Kos, Greece

Francesco PetriniKonstantinos GkoumasFranco 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 RomeDipartimento di Ingegneria Strutturale e Geotecnica

Recent developments and uncertainty aspects in the performance based design of structures for wind

Recent developm


ind



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

Recent developm


ind




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




Recent developm


ind



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 profileVm

Mean wind velocity profile

Vm+ v(t)Turbulent wind velocity profile

ENVIRONMENT EXCHANGE ZONE

Recent developm


ind



5

Types of uncertainties

ENVIRONMENT

Wind actions

Structural systems

Non environmental

actions

EXCHANGE ZONE

1. Aleatory2. Epistemic3. Model

Interaction parameters

Structural parameters

Site-specific Wind

Aerodynamic and aeroelastic

phenomenaWind site basic

parameters

Intensity measure



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

Recent developm


ind



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(DVDM) · f(DMEDP) · f(EDPIM, IP,SP) · f(IPIM,SP) ·

· f(IM) · f(SP) · dDM · dEDP · dIP · dIM · dSP

Interaction Parameters

Structural Parameters

Intensity measure

IM IP SPEngineering Demand Parameters

EDPDamage Measure

DMDecision Variable

DV

Recent developm


ind



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

Interactionanalysis

Structural analysis Damage analysis Loss analysis

IM: intensity measure

IP: interaction parameters

EDP: engineering demand param.

DM: damage measure

DV: decision variable

SelectO, D

O: location

D: design

Environment 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.

Recent developm


ind



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

Aerodynamicanalysis

Struc’l analysis Damage analysis Loss analysis



EDP: engineering demand parameters

DM: damage measures DV: decision variables

SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



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

Aerodynamicanalysis

Struc’l analysis Damage analysis Loss analysis



EDP: engineering demand parameters

DM: damage measures DV: decision variables

SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



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



DM: damage measure


SelectO, 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



DM: damage measure


SelectO, D

O: location

D: design

Facility info

Decision-making

PB

WE

PB

EE

Recent developm


ind




9

• Overview of the Performance Based Wind Engineering (PBWE) procedure.





Recent developm


ind



10

Tam

ura

, Y

. (2

009

).

Win

d an

d ta

ll bu

ildin

gs,

Pro

cee

ding

s of

th

e F

ifth

Eur

ope

an &

Afr

ican

Co

nfe

renc

e on

Win

d E

ngin

eerin

g (E

AC

WE

5),

F

lore

nce,

Ita

ly,

July

19-

23,

200

9..

Vibration frequency

Acc

ele

ratio

n t

hre

sho

lds

for

mo

tion

p

erc

ep

tion

w(t;z2)Vm(z2)

Vm (z1)

Vm (z3)

V(t;z2)

v(t;z2)u(t;z2)

X

Z

Y

θ

B1B2

H

Loss of serviceability

Loss

of

inte

grity

of

non

-str

uctu

ral

elem

ents

Mot

ion

perc

eptio

n by

bui

ldin

g oc

cupa

nts

Dis

pla

cem

ent

s

Acc

eler

atio

n

Discomfort level in terms of perception thresholds

1

Recent developm


ind



11

Loss of serviceability

Loss

of

inte

grity

of

non

-str

uctu

ral

elem

ents

Mot

ion

perc

eptio

n by

bui

ldin

g oc

cupa

nts

Bas

hor,

R

. an

d K

aree

m,

A.

(200

7).

"Pro

babi

listic

P

erfo

rman

ce

Eva

luat

ion

of

Bui

ldin

gs:

An

Occ

upan

t C

omfo

rt P

ersp

ectiv

e",

Pro

c. 1

2th

Inte

rnat

iona

l C

onfe

renc

e on

Win

d E

ngin

eerin

g, 1

-6 J

uly,

Cai

rns,

Aus

tral

ia.

Ava

ilabl

e on

line

at h

ttp://

ww

w.n

d.ed

u/~

nath

az/ [

Acc

esse

d 15

Jun

e 20

10].

w(t;z2)Vm(z2)

Vm (z1)

Vm (z3)

V(t;z2)

v(t;z2)u(t;z2)

X

Z

Y

θ

B1B2

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

1

10

100

0,1 1

a [

cm/s

2 ]

f [Hz]

Office Apartment

Italian Guidelines

f1

Sca

lar

thre

sho

ld

Dis

pla

cem

ent

s

Acc

eler

atio

n

Recent developm


ind



12

Case study structure

Structure•74 floors•Height H=305m•Footprint B1=B2=50m (square)

3d f

ram

e on

the

ext

erna

l pe

rime

ter

cent

ral c

ore

Bracing system

A steel high-rise buildingFinite Element model

B1B2

H

FE ModelApproximately•10,000 elements•4,000 nodes•24,000 DOFs

Recent developm


ind



13

Experimental model of Actions

Spe

nce

S.M

.J.,

Gio

ffrè

M.,

Gus

ella

V.,

In

flue

nce

of

high

er m

ode

s on

the

dy

nam

ic r

e-sp

onse

of

irreg

ular

and

re

gula

r ta

ll bu

ildin

gs,

Pro

c. 6

th

Inte

rnat

iona

l C

ollo

quiu

m

on

Blu

ff

Bod

ies

Aer

ody

nam

ics

and

App

lica

tions

(B

BA

A V

I),

Mila

no,

Ital

y, J

uly

20-

24,

2008

.

Boundary Layer Wind Tunnel of the CRIACIV in Prato, Italy

-60

-40

-20

0

20

40

60

80

100

120

140

3000 3200 3400 3600 3800

F [KN]

t [s]

Along Across

1:50

0

Sca

le m

od

el

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

Recent developm


ind



14

)(),(

),,(exp1

),(),(

22

212

2

hSVc

dAdAfA

hSVchS

uumxD

A A

uumxDDD tt

)(),h(S

)(HVc

),h(S)(H),h(S

2uu

22mxD

DD

2

rr tttt

2

0

2

2

20

2

20

2

2

41

1

1)(

mH

rrmp grr 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

2kj

2z

jkzVzV2π

zzCωωf

Cross-spectrum

5.0

0

uu2xu 200

300(x)dxRu

1L

z

where:

5/3

ju

jux2

uuu

/zLf10.3021ω/2π

/zLfσ6.686ωS

jj

2fri0

0

u2u

u1.75)log(zarctan1.16

(n)dnSσ

)z(V2π

zωf

jm

j

Autospectrum

3ew(t)2ev(t)1eu(t))j(zmV)jz(t;jV

α

10m10

zV(z)V

So

lari,

G.

Pic

card

o,

G.

(20

01

). P

rob

ab

ilist

ic 3

-D t

urb

ule

nce

mo

de

ling

fo

r g

ust

bu

ffe

ting

of

stru

ctu

res,

Pro

ba

bili

stic

En

gin

ee

ring

Me

cha

nic

s, (

16

), 7

3–

86

.

Tur

bule

nt w

ind

velo

city

spe

ctra

(a

naly

tical

)

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 Force spectrumTurbulence force spectrumVortex shedding force spectrum

Recent developm


ind



15

Recent developm


ind



16

Recent developm


ind



17

Hazard analysis

)(10

1)(10

10, exp)(

)(),(f

10

kk

V c

V

c

V

c

kV

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

Interactionanalysis





DM: damage measure


SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



Structural system

info

Recent developm


ind



18


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

Interactionanalysis





DM: damage measure


SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



Structural system

info

Recent developm


ind



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

Interactionanalysis





DM: damage measure


SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



Structural system

info


462.2507.1265.0 2 rg

122if650

122if46

213

45

2

21

.T.

.T.

)Tln(

.

)Tln(

.

windr,e

windr,e

windr,e

windr,e

gr

1690if

690100if

380631 450

r

r

r

r.

r

r,e

q.

.q.

.q.

r

rr

(Obtained from time-domain analyses)

The peak response factor gr is characterized by a Gaussian distribution function

g*r = -0.2562 + 1.507 + 2.462

3.00

3.40

3.80

4.20

4.60

0.5 1 1.5 2 2.5

g*r

[%]

rg

rg

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. 0

0.2

0.4

0.6

0.8

1

1.2

-90 -60 -30 0 30 60 90

Mea

n ae

rody

nam

ic c

oeff

icie

nts

θ [deg]mCD mCLμCD μCL

DC

0

0.2

0.4

0.6

0.8

1

1.2

-90 -60 -30 0 30 60 90

Mea

n ae

rody

nam

ic c

oeff

icie

nts

θ [deg]mCD mCLμCD μCL

LC

rrmp grr

Recent developm


ind



20

EDP = aLp

G(EDP) = ∫…∫ G(EDPIM, IP, SP) · f(IPIM,SP) · f(IM) · f(SP) · dIP · dIM · dSPMonte Carlo sim

(5000 runs)

w(t;z2)Vm(z2)

Vm (z1)

Vm (z3)

V(t;z2)

v(t;z2)u(t;z2)

X

Z

Y

θ

B1B2

H

aLp

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

Interactionanalysis





DM: damage measure


SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



Structural system

info

Structural analysis


Recent developm


ind



21

Risk Curve. EDP= aLp = 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.

w(t;z2)Vm(z2)

Vm (z1)

Vm (z3)

V(t;z2)

v(t;z2)u(t;z2)

X

Z

Y

θ

B1B2

H

aLp

G(a

Lp )

aLp [mm/s2]

Ciampoli, M. & Petrini, F., 2012, Performance-Based Aeolian Risk assessment and reduction for tall buildings, Probabilistic Engineering Mechanics, 28 (75–84).


Recent developm


ind



22

TMD

Design Parameters

γ = mTMD/mtot

β = ωTMD/ ω1

ξ* = damping of TMD

90

0.125 0.145 0.165 0.185

β = 0.70 ; ξ* = 1% - 10% β = 0.80 ; ξ* = 1% - 10%

β = 0.90 ; ξ* = 1% - 10% β = 1.02 ; ξ* = 1% - 10%

β = 1.10 ; ξ* = 1% - 10% β = 1.20 ; ξ* = 1% - 10%

β = 1.30 ; ξ* = 1% - 10% Uncontrolled

Apartment Office

a Lp

[mm

/s2 ]

n [Hz]

β = ξ* =

β = ξ* =

β = ξ* =β = ξ* =

β = ξ* =

β = ξ* =

β = ξ* =

G(a

Lp )

aLp [mm/s2]

Parametric analysis Effects on risk

γ = 1/150

Aeolian Risk reduction using TMD


Recent developm


ind




23






Recent developm


ind



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

Interactionanalysis





DM: damage measure


SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



Structural system

info

Recent developm


ind



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

Interactionanalysis





DM: damage measure


SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



Structural system

info

Damage analysis

Probabilistic damage analysis: assign a probability distribution to the perception thresholdsProcedure: 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.


Recent developm


ind



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

Interactionanalysis





DM: damage measure


SelectO, D

O: location

D: design

Environment info

Decision-making

D

f(SP|D)

f(SP)



Structural system

info

Loss analysis

Probabilistic loss analysis: assign a cost probability for different damagesIssues: the uncertainty in the cost relies on various factors (e.g. market trend)

DM

Non structural elements

Structural elements

Comfort

SafetyServiceabilitySafety

Serviceability

DVDirect

Indirect

(As a direct damage to the structure)

(As a consequence of the damaged structure)

IM

SPIP 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.


Recent developm


ind




27






Recent developm


ind



• 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

Recent developm


ind



Thank you for your attention

29

Francesco Petrini, Konstantinos Gkoumas, Franco BontempiSapienza - University of Rome, Dipartimento di Ingegneria Strutturale e Geotecnica

Acknowledgements:Prof. Marcello Ciampoli, Prof. Giuliano AugustiThis study is partially supported by StroNGER s.r.l. from the fund “FILAS - POR FESR LAZIO 2007/2013 - Support for the research spin-off”.

Compdyn kg

Technology

Transcript of Compdyn kg