PBWE - IN VENTO 2014 - Petrini StroNGER.com

Building occupant comfort
assessment in the PBWE framework
Francesco Petrini*, Pierluigi Olmati, Franco Bontempi
francesco.petrini@uniroma1.it , francesco.petrini@stronger2012.com
--
*Research Associate,
School of Civil and Industrial Engineering, Sapienza Università di Roma
Via Eudossiana 18 - 00184 Rome (ITALY)
tel. +39-06-44585072
StroNGER S.r.l., Co-founder and Director
Via Giacomo Peroni 442-444, Tecnopolo Tiburtino, 00131 Rome (ITALY)
--
Genova 25 June 2014

- Building occupant comfort
- PBWE: state of development
- Objective of this study
Intro
Francesco Petrini.
francesco.petrini@uniroma1.it

Building occupant comfort – issues
In-Vento2014.June22-252014
Approach to the
problem (comfort thresholds)
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions
Francesco Petrini. Co-founder and Director
francesco.petrini@uniroma1.it 3

francesco.petrini@stronger2012.com
4
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions
Field experiment and surveys
Motion simulator and shake table
Field experiment with artificial excitation
K. C. S. Kwok, P. A. Hitchcock, M. D. Burton.(2009). “Perception of vibration and occupant comfort in wind-
excited tall buildings”, Journal of Wind Engineering and Industrial Aerodynamics, 97 (2006), 368-380.
Approach to the
Some discordance
between the results
obtained by different
authors

5
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions
Human behavior/
psychology
Occupants
Owners
Rest of the
population
(building
reputation)
Wind field
Structural system
(e.g. damping)
Aerodynamics
(e.g. vortex shedding)
Age, occupation,
position,….
INTERACTIONS
C. Pozzuoli, G. Bartoli, U. Peil, M. Clobes (2013). "Serviceability wind risk assessment of tall buildings including
aeroelastic effects" J. Wind Eng. Ind. Aerodyn. 123 (2013), 325–338.
Approach to the

Approach to the
6
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions
Wind direction
Oscillation
Wind storm duration
Waveform
Frequency
Amplitude
Significant parameters
for describing the
structural response
Peak accel.
RMS of accel.
T. Kijewski-Correa, D. Pirnia (2009). “Pseudo-Full-Scale” Evaluation of Occupant Comfort in Tall Buildings. 11th
Americas Conference on Wind Engineering, San Juan, PR, USA June 22-26, 2009

Approach to the
7
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions Shape
Control
Damping
Optimization
http://www.squidoo.com/taipei101
…
Spence, S.M.J., Gioffrè, M. (2012), “Large Scale Reliability-Based Design Optimization of Wind Excited Tall
Buildings”, Probabilistic Engineering Mechanics, 28: 206-215.
K. T. Tse, K. C. S. Kwok and Y. Tamura (2012). “Performance and Cost Evaluation of a Smart Tuned Mass Damper
for Suppressing Wind-Induced Lateral-Torsional Motion of Tall Structures”. Journal of Structural Engineering, 138(4)
http://misfitsarchitecture.com/tag/atkins/
http://www.ctbuh.org

Approach to the
8
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions
Structure
Wind-structure interactions
Environment (free-field wind)
Perception thresholds, task disruptions thresholds
…..
Ciampoli M., Petrini F., Augusti G., (2011). “Performance-Based Wind Engineering: towards a general procedure”,
Structural Safety, 33 (6), 367-378

Approach to the
9
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions
Petrini F., Gkoumas K., Bontempi F. (2013). “Damage and loss evaluation in the performance-based wind
engineering”, ICOSSAR 2013 Conference, June 16-20 2013, Columbia University, New York, USA
Loss analysis
Damage analysis
- 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.

Approach to the
10
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions
Do we have a rational and
coherent tool to potentially
manage all these issues?
francesco.petrini@suniroma1.it

Approach to the
francesco.petrini@suniroma1.it
11
Prominent factors
Main analysis
parameters
Uncertain aspects
Monetary supremacy
Design solutions
Do we have a rational and
coherent tool to potentially
manage all these issues?
YES, we have the Performance
Wind Engineering (PBWE)
approach

A PBWE Framework from Rome
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
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 IPSP
Engineering
Demand
Parameters
EDP
Damage
Measure DM
Decision
Variable DV
G(·|·) is a conditional
complementary
cumulative
distribution function
f(·|·) is a conditional
probability density
function= progress with respect to the
Performance-Based Seismic Design
*
* *
Extension of the
Performance-Based
Seismic Design
procedure proposed by
PEER Research center
Ciampoli M., Petrini F., Augusti G., (2011). “Performance-Based Wind Engineering: towards a general procedure”, Structural Safety, 33 (6),
367-378

14
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
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 task disruptions thresholds
Procedure: obtain a pdf that assigns at each vibration level a percentage of persons that experience discomfort
Vibration and occupant comfort issues
Not developed in literature for non-hurricane winds (Caracoglia and Seo did something on Bridges with
respect to flutter; Tse, Kwok and Tamura evaluated the costs of a TMD for
suppressing 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.
Ciampoli et al. 2011Petrini et al. 2012
Spence et al. 2013
14

Starting point. Past studies (I): Case study
Loss of serviceability
Lossofintegrityof
non-structural
elements
Motionperception
bybuilding
occupants
Displacements
Accelerations
Reduced formulation
Structure
• 74 floors
• Height H=305m
• Footprint B1=B2=50m
FE Model
Approximately
• 10,000 elements
• 4,000 nodes
• 24,000 DOFs
centralcore
3dframeontheexternalperimeter
Bracingsystem
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
15
G(EDP) = ∫…∫ G(EDP|IM, IP, SP) · f(IP|IM,SP) · f(IM) · f(SP) · dIP · dIM · dSP
15

1
10
100
0,1 1
a[cm/s2]
f [Hz]
Office Apartment
Starting point. Past studies (II): occupant comfort
Lossofintegrityof
non-structural
elements
Motionperception
bybuilding
occupants
Displacements
Accelerations
DETERMINISTIC Perception
thresholds for occupant comfort
Annual occurrenceStochastic variables
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
16
Ciampoli M, Petrini F. (2011). “Performance-Based Aeolian Risk assessment and reduction for tall buildings”, Probabilistic Engineering
Mechanics, 28, 75–84.
EDP = aL
p
TMD
16

1
10
100
0,1 1
a[cm/s2]
f [Hz]
Office Apartment
Starting point. Past studies (II): occupant comfort
Lossofintegrityof
non-structural
elements
Motionperception
bybuilding
occupants
Displacements
Accelerations
DETERMINISTIC Perception
thresholds for occupant comfort
Annual occurrenceStochastic variables
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
17
Ciampoli M, Petrini F. (2011). “Performance-Based Aeolian Risk assessment and reduction for tall buildings”, Probabilistic Engineering
Mechanics, 28, 75–84.
EDP = aL
p
TMD
17

Damage analysis
Francesco Petrini.
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
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

Fragility: the fragility in terms of damage measure G(DM|EDP) in this case can be specialized
as G(NP≥np|a)
Where
Np =random variable describing the number of people perceiving the motion
np = specific value assumed by Np , thus representing the limit state
f(a)= PDF of the engineering demand parameter (EDP)
G= Cumulative Distribution Function
DM=Np
Definition of the damage index
Damage definition: someone building occupant perceives the motion (NOTE THAT this will not
necessarily cause a task disruptions);
Damage Measure (DM): number of building occupants perceiving the motion (under the
assumption that this number is directly proportional to the number of occupants suffering for a
task disruptions);
19

G( Np> np | a ) = 1
G( Np > np | a ) = 0
a
b
c
a[mm/s2]
f [Hz]
Np= np
fn
∆a
sample i
a [mm/s2]
a
c
b
G(Np>np|a)
fn
∆a
∆a: acceleration range
where the fragility
varies due to the
uncertanties
The results from literature (all author) on the motion perception provide several curves, each one (specific author)
representing the acceleration threshold for which a certain number of people (np e.g. 5%) perceives the motion as a function
of the fundamental natural frequency of the building.
Focusing on a specific number of people perceiving motion, different authors provided different curves, and these curves do
not match because the uncertainty and variability of the motion perception of the building occupants (variability of the group
of people - aleatory uncertainty) and because of the different approach used by the authors in assessing it (error in measures
or different measure technique - epistemic uncertainty).
How we can quantify the fragility? – literature data and STRONG assumptions
20
(Single author)
ASSUMPTIONS
• Considering a specific frequency (e.g. the first structural natural frequency of the building), the value of the acceleration
threshold for which np people perceive the motion is hypothesized to be log-normally distributed.
• Task disruptions coincides with motion perception
• Subjects do not show differences of sensitively between sinusoidal and random motions (aggregation of different
experiments from literature – neglecting part of the epistemic uncertainty)
• The effects of body posture, motion direction, age, sex (Kanda et al., 1988) are not deeply significant in comparison with
the individual differences in the motion perceptions thresholds (invariability of the statistics on perception with the
differences in group of people – neglecting part of the aleatory uncertainty).
Interpretationofthedata
fromtheliterature

0
20
40
60
80
100
120
140
160
0 25 50 75 100
Chen and Robertson, 1972
Tamura et al., 1988
Kanda et al., 1994
Tamura et al., 2006 (1)
a[mm/s2]
Np [%]
fn=0.187 Hz
-0.25
0
0.25
0.5
0 25 50 75 100
Np [%]
fn=0.187 Hz
([-]
Acceleration thresholds in function of Np for the structural natural frequency of 0.1873 Hz.
21
Literature crude results Dispersion of the results
Result for the case-study building – literature data

0
0.25
0.5
0.75
1
0 20 40 60 80
G(Np≥np|a)
a [mm/s2]
original design
modified design
In-Vento2014.June22-252014In-Vento2014.June22-252014
Result for the case-study building – fragility

• We have some design measures (e.g. insertion of passive control devices)
for reducing the vibration perception of building occupants. But the
effectiveness of the measure must be evaluated in terms of cost (by
computing the probability of exceeding acceptable values of an
appropriate DV).
• PBWE is a powerful tool for this purpose
• Damage and loss analysis of wind-induced vibrations need to be based on
corroborated literature studies.
• A lot of research work is necessary in order to characterize the
uncertainties affecting the problem.
23
Conclusions and further research
23
RINGRAZIAMENTO
Un caro ringraziamento a MARCELLO CIAMPOLI (deceduto il 13 Dic. 2013), che mi ha
insegnato veramente tanto sulla ricerca (principalmente sul PBD) ma che, soprattutto, mi
ha insegnato che non bisogna mai prendersi troppo sul serio.
Francesco Petrini
(25/06/2013)

PBWE - IN VENTO 2014 - Petrini StroNGER.com

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