Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion – Israel Institute of Technology
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Aim of the talk
 Present ongoing research in which the presenter has
been involved.
 Various types of energy dissipation devices will be
discussed.
 Various structural systems (e.g. frames, walls etc.) are
considered.
 How (and if) to use such devices in cultural heritage
buildings?
discussion with the audience (future
collaboration?).
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Acknowledgement







Prof. G.P. Cimellaro.
Dr. Y. Daniel.
Prof. G.F. Dargush.
Dr. S. Dogruel.
Prof. R. Levy.
Prof. A.M. Reinhorn.
Prof. A. Rutenberg.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Presentation layout




Motivation and introduction
Various energy dissipation devices.
Various design approaches (as time allows).
Conclusions
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Motivation
 Codes were aimed at preventing loss of human life
while permitting a heavy damage to structures and
property under strong earthquakes
 Heavy damage was caused by the 1994 Northridge
and the 1995 Kobe earthquakes.
 Performance-Based-Design.
 Retrofitting of existing structures:
 Passive control devices
 Goal: develop optimal design
methodologies
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Energy dissipation devices
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Energy dissipation devices
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Tuned Mass Dampers - TMDs
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Weakening
f

a
 Accelerations (forces) are reduced
 Inter-story drifts are increased
 Combination with viscous dampers
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
m
f 2
f 2
f  ma
O. Lavan
Technion - IIT
Gap and objective
 The design process has become increasingly complex.
What type of damper is good for what purpose
(hazard, type of damage to be controlled, type of
structural system)?
Once a type of damper is chosen, how can one come
up with an efficient design?
 Most design methodologies lead to “expensive” designs.
 Optimal design methodologies require understanding of
concepts and tools from optimization theory.
 Develop practical optimal design methodologies.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Requirements from the design
methodology
 Assist in choosing the right type of device
 General for all types of devices and objectives
 Lead to an efficient (optimal?) performance-based
solution
 Small computational effort
 Simple and transparent to practicing engineers: Make
use of tools familiar to the engineering community
 Lead to understanding of the behavior of the optimal
designs
 Unfortunately, there is no single method that can
satisfy all requirements.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Strategy – levels of optimization
 Identify what retrofitting technique is advantageous for what
purpose and what characteristics optimal designs have.
Experience.
Multi-objective zero order optimization scheme (GA).
III
 Identify what characteristics optimal designs of specific
problems have.
Gradient based approach
Multi-objective zero order optimization scheme (GA).
I
 Taylor simple design methods for specific
considering insight from the results attained.
Simple iterative approach
II
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
problems
O. Lavan
Technion - IIT
Single objective gradient based approach
Lavan, O., and Levy, R. (2005). "Optimal design of supplemental viscous
dampers for irregular shear-frames in the presence of yielding."
Earthquake Engineering & Structural Dynamics, 34(8), 889-907.
Lavan, O., and Levy, R. (2006). "Optimal peripheral drift control of 3D
irregular framed structures using supplemental viscous dampers."
Journal of Earthquake Engineering, 10(6), 903-923.
Lavan, O., and Levy, R. (2006). "Optimal design of supplemental viscous
dampers for linear framed structures." Earthquake Engineering &
Structural Dynamics, 35(3), 337-356.
Lavan, O. and Levy, R. (2010) "Performance based optimal seismic
retrofitting of yielding plane frames using added viscous damping."
Earthquakes and Structures 1(3): 307-326.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Problem Formulation
J  c  1the total added damping
Minimize
T
mininimize :
d
subject to :


h
xf

to

1
all

m
x

t

where xt , x t , xt  and f h t  satisfy the equations of motion
 a g  ensemble i

Mxt   C  C d c d  x t   K α xt   B fx f h t   M  e  a g t  ; x0   0, x 0   0

fh t   f x t , f h t  ; f h 0   0



0  c d  c d,max
Various
performance
f t inter-story
  B x tat
dt each
   Denergy
1
Hysteretic
plastic hinge
at each story
 max  Hindices
d  D dInter-story
xt    1drift at each story
E h t f   D E
1
tf
all
h
Equations of motion
Whole
ensemble
Size limitations
• Gradient Based Opt
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
10
10
9
9
8
8
7
7
Floor number
Floor number
Characteristic results
6
5
4
6
5
4
3
3
2
2
1
1
0
1
2
allowable
0
0.5
1
1.5
4
x 10
optimum damping [kN*sec/m]
maximal drifts [%]
dampers are assigned only where the performance
index is full
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Single objective simple iterative approach
Viscous dampers
Lavan, O., and Levy, R., (2005), “Optimal seismic retrofit of irregular 3D framed
structures using supplemental viscous dampers”, Proceedings of the 4th
European Workshop on the Seismic Behavior of Irregular and Complex
Structures, Aug. 26-27, Thessalonica, Greece, Paper no. 52.
Levy, R., and Lavan, O. (2006). "Fully stressed design of passive controllers in
framed structures for seismic loadings." Structural and Multidisciplinary
Optimization, 32(6), 485-498.
Lavan, O., and Levy, R., (2009) "Simple iterative use of Lyapunov’s solution for the
linear optimal seismic design of passive devices in framed buildings." Journal
of Earthquake Engineering, 13(5), 650–666.
Hysteretic dampers
Daniel, Y., Lavan, O, Levy, R. (2011) "A simple methodology for the seismic passive
control of irregular 3D frames using friction dampers." 6WEICS – 6th
European Workshop on the seismic behavior of Irregular and Complex
Structures, Haifa, Israel.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Single objective simple iterative approach
Multiple Tuned Mass dampers
Daniel, Y., Lavan, O. (2011) "Seismic design methodology for control of 3D
buildings by means of multiple Tuned-Mass-Dampers." COMPDYN 2011 - 3rd
International Conference in Computational Methods in Structural Dynamics
and Earthquake Engineering, Corfu`, Greece.
Lavan, O., Daniel, Y. (2013) "Full resources utilization seismic design of irregular
structures
using multiple tuned mass dampers." Structural and
Multidisciplinary Optimization, 48(3), 517-532
Weakening and damping
Lavan, O. (2010) "Seismic design procedure for total accelerations and inter-story
drifts reduction of existing and new buildings with protective systems."
Structures Congress 2010, Orlando, Florida.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Analysis/Redesign
dampers are assigned only where the performance
index is full
1.
Perform time-history analysis.
2.
Design new damping using the
recurrence formula.
cd i
3.
Jan. 19-20, 2014
Jerusalem, Israel
k 1
 cd i
k 
pi 
k 
i
1
q
Return to stage 1 if the results are
not satisfying.
Seismic retrofitting of buildings using
energy dissipation devices
pii(k)
cdi(k)
pij(k)
cdj(k)
O. Lavan
Technion - IIT
Convergence
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Convergence
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Convergence – hysteretic dampers
2
sum(k ) / sum( k final)
0
1.8
0
driftmax/driftallowable
ratio
1.6
1.4
1.2
1
0.8
0
10
20
30
40
50
60
iteration number
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Convergence - MTMDs
After the third modification, the added mass of TMDs increased
to 4.6%. Upon convergence, the properties of each TMD were:
Frame
1
3
4
Floor Mode to dampen Final mass (ton) Final stiffness (kN/m)
4
3
3.96
416.10
8
5
0.44
139.13
8
2
78.08
2974.8
Final damping ratio
0.0655
0.0267
0.2062
8
8
7
7
7
7
6
6
6
6
5
4
3
2
atall
1
0
1
2
envelope total acceleration (g)
Jan. 19-20, 2014
Jerusalem, Israel
5
4
3
5
4
3
2
2
1
1
0
1
2
envelope drift (%)
story number
8
floor number
8
story number
floor number
TIME domain
0
5
4
3
2
atall
1
2
envelope total acceleration (g)
Seismic retrofitting of buildings using
energy dissipation devices
1
0
1
2
envelope drift (%)
O. Lavan
Technion - IIT
Convergence W+D
m=1.0 ton
K5=789.6kN/m
Normalized values
3
m=1.0 ton
2.5
Fy5=7.29kN
K4=1421.2kN/m
2
max drift
max acceleration
total damping
total capping force
1.5
m=1.0 ton
Fy4=13.46kN
K3=1895.0kN/m
1
m=1.0 ton
Fy3=18.24kN
0.5
0
K2=2210.8kN/m
0
2
4
6
8
Iteration number
10
12
m=1.0 ton
Fy2=21.20kN
K1=2368.7kN/m
Fy1=22.23kN
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Multi-objective optimal seismic
retrofitting of buildings
Lavan, O., and Dargush, G. F., (2009) "Multi-objective optimal seismic
retrofitting of structures." Journal of Earthquake Engineering, 13,
758–790.
Dogruel, S., Lavan, O. (2010) "A comparative study of the seismic
retrofitting of structures using various innovative technologies." 14th
European Conference on Earthquake Engineering. Ohrid, Republic of
Macedonia.
Dogruel, S., Lavan, O. (2012) "A comparative study of seismic retrofitting
of a steel benchmark structure using various types of passive
controllers.” Structures Congress 2012, Chicago, Illinois
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Optimization objectives
 Maximal normalized inter-story drift
of all selected locations.
 Maximal normalized total acceleration
of all selected locations.
 Cost
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
1 2
O. Lavan
Technion - IIT
Multi-objective opt. – why?
Drifts
Acc.
Cost
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Multi-objective opt. – why?
 Traditional optimization
Cost
Cd1=X
Cd2=Y
Cd2
Cd1
Cd1=Y
Cd2=Z
Optimal
?
Optimal
Drift
 A small compromise on the performance
may lead to a much cheaper solution.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Pareto front
 A design is Pareto optimal if there exists no feasible design
which would decrease some objective without causing a
simultaneous increase in at least one other objective.
Cost
Pareto
Optimal
Pareto
Optimal
Pareto
Optimal
Pareto
Front
Pareto
Optimal
Pareto
Optimal
Drift
 Decision is made when the whole picture is at hand (choose
best compromise).
 Large computational effort
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Example
m=1.0 ton
K5=789.6kN/m
m=1.0 ton
Fy5=7.29kN
K4=1421.2kN/m
m=1.0 ton
Fy4=13.46kN
K3=1895.0kN/m
m=1.0 ton
Fy3=18.24kN
K2=2210.8kN/m
m=1.0 ton
Fy2=21.20kN
K1=2368.7kN/m
Fy1=22.23kN
Jan. 19-20, 2014
Jerusalem, Israel
 With the right design all
types of dampers can
reduce both objectives.
 Viscous dampers are
more
efficient
in
reducing both objectives
simultaneously.
 There is a wide region
where a large reduction
of drifts is accompanied
with only a small
increase in accelerations
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
Example
 The weakening and
damping approach is
more
efficient
in
reducing both objectives
simultaneously.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT
EDDs in wall structures
Rigid floor
Lavan, O. (2012). "On the efficiency of viscous dampers in reducing various
seismic responses of wall structures." Earthquake Engineering and
Structural Dynamics 41:1673–1692.
H
 A single parameter controls the
response of VCSW.
 It does not depend on the height of
the structure. Hence, this system is
also efficient for low rise buildings.
 Based on the example, such a
reduction is feasible using "off-theshelf" dampers.
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
cd
EI
EI
O. Lavan
Technion - IIT
Open questions
 The research done by the author so far focuses on
“modern” buildings.
 How to use such devices in cultural heritage
buildings?
 Some research on that has been done by others.
 (Maybe) There is more room for research on that
topic.
Thank you!
Jan. 19-20, 2014
Jerusalem, Israel
Seismic retrofitting of buildings using
energy dissipation devices
O. Lavan
Technion - IIT