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Combined computational-experimental approach
towards quantifying the structure resilience
Prof. Adnan Ibrahimbegovic, (Classe Exceptionnelle)
Univ. Technologie Compiegne/ Sorbonne Universites, Paris, France
Acknowledgements : “Structures under extreme conditions”
MENRT, EDF, CEA/DAM, IRSN …
Two hundred years of modeling of concrete and challenges
for the next century (Adnan Ibrahimbegovic, France)
Colosseum, Rome
- Studies : PhD Structural Eng. Mechanics Materials: University of California, Berkeley, USA 1989Habilitation in Mechanics: Université Pierre et Marie Curie, Paris, France 1997
Fullbright Fellowship for Yugoslavia (1 /8 excellence awards) 1986« George and Helen Popert » Scholarship, University of California, Berkeley 1987UC Berkeley Regents Scholarship, University of California, Berkeley 1988
NSERC International Fellowship, Canada : 1994Hôte académique, Ecole Polytechnique Fédérale, Lausanne, Switzerland 1998-9, 2000-5
NATO Fellowship for Croatia, Slovenia 2005, 2006
Alexander von Humboldt Research Award ‘Technischen Mechanik’, Germany 2005Fellow IACM Award, International Association of Computational Mechanics 2006Slovenian Science Foundation Research Award, Slovenia 2007Classe Exceptionnelle of University Professors (CNU60), France 20092010: France-India; 2011: France-Berkeley; 2012: Chair Claude Levy-Strauss USP Brazil;2013 Chair Asgard Norway; 2014: TUBITAK Professor TU Istanbul, Turkey;2014: OSCE Professor KAIST S. Korea; 2014: Mercator-Professor TU-Braunschweig, Germany2015 IUF – Institut Universitaire de France - Membre Senior
- Studies Awards :
… in recognition of a researcher's entire achievements to date to academics whose fundamental discoveries, new theories, or
insights have had a significant impact on their own discipline and who are expected to continue producing
cutting-edge achievements in future …
Professor Adnan Ibrahimbegovic, Chaire de MécaniqueE-mail: [email protected]
- Carrier Awards :
Evidence of efforts and ability to inspire young researchers:
Former: post-doc (5), thesis (31) + Habilitations: (5) current positions
of my former students:
-with each of the top engineering schools in Paris (ENPC, ECP, ESTP);
-with well-known technology institutes (MIT-Boston, PEER Center UC-Berkeley.
UT-Compiegne, INSA-Toulouse, Univ. Nantes, Univ. Lille);
-with a number of French industry leaders (AREVA, EDF, Lafarge, Renault);
-with computer software developers (ALTAIR, ESI, SAMTECH);
-and university professors in 10 countries (France, Mexico, Czech Republic,
Slovenia, Vietnam, Algeria, Bosnia, Hungary, Turkey, Croatia)Current: -post-docs (2): E. Marenic, M. Nikolic
-doct. students (9): A. Boujelben, X-N. Do,
E. Hajdo (co-ad. Dr. Dolarevic, Univ. Sarajevo),
E. Hadzalic, I. Imamovic, E. Karavelic ( “ ),
T. Rukavina (co-ad. Dr.. Kozar. Univ. Rijeka),
M. Sarfaraz (co-ad. Dr. Matthies, TU Braunschweig)
A. Stanic (co-advisor Dr. Brank, Univ. Ljubljana).
I Research Background & Accomplishments [past & current works](b) Identifying some of the key previous research accomplishments
Chaire de Mécanique « PICARDie »
Lecture outline:
1. Resilience quantification = system of systems
2. Material vs. structure: probability aspects
3. Combined extreme loading conditions
(earthquake, tsunamis, explosions, fires)
4. Conclusions
Pr Adnan Ibrahimbegovic
6
Earthquakes: First cause of Human Casualties due to Natural Disasters
Worldwide
Assisi, IT, 1997Azores, PT, 1998 Athens, GR, 1999
Molise, IT, 2002
Turkey, 1999Iran, 2003
Japan, 2004
Material vs. structure: probability
World seismic map
--Worst case scenario:i) Cooling liquid loss in the
case of ‘extreme accident’
in a nuclear power plant
ii) Durability issues
Q: Crack spacing and opening ? Collaboration : EDF, IRSN,
CE
Nuclear power plant: Durability problem (30 60 years !)
ENS/LMT-thesis D. Markovic [2001-2004], N. Dominguez [2001-2005]S. Melnyk [2004-2007], A. Kucerova, [2004-2007], M. Hautefeuille [2005-2009], B-H. Pham [2006-2009], A. Boulkertous [2005-9], N. Benkemoun [2007-2010],B. Ayhan [2009-2013], M. Jukic [2010-2013], V-M. Ngo [2011-2014] …
Material vs. structure: probability
Conclusions (in 1990): Solution methods under control
Need for better interpretations of inelastic failure mechanisms
Performance based design – early works 1992
at UC Berkeley, USA SAP, CSI
Material vs. structure: probability
New Issues:
RESILIENCE-BASED
DESIGN (better
understandig of damage
Mechanisms …
Different sources
of damping -
-new idea:
avoid Rayleigh
(non-physical )
Damping …–
Move from Structural
to Material
Point of view
P. Jehel, A. Ibrahimbegovic, P. Leger, L. Davenne Concrete Comp. [2010]
Material vs. structure: probability
Maquette CAMUS 2000
Fissuration ˆ la base dÊÕun mur apr�s essai
National Project CAMUS-2000
Seismic response of RC walls with/without torsion(thesis: G. Casaux, enc.: J. Mazars, L. Davenne, F. Ragaueneau,A Ibrahimbegovic)
Partners : LMT-Cachan, INSA-Lyon, LGS/ CEA Sacley …
Funding: Ministry of Equipment
Reduced Reinforcement. … “French Walls”
Davenne, Ragueneau, Mazars, Ibrahimbegovic [2003] Comp.Struct.
-Collab.: Ecole Polytechnique, Montreal, Quebec, Canada,
University of California, Berkeley, USA
University of Ljubljana, Slovenia
Technical University of Istanbul, Turkey
Local measurements
+ result interpretation
Material vs. structure: probability
Conclusions:
Rayleigh damping (single parameter) CAN NOT match all 3 phases
not the same cumulative damage !
Model based on ENERGY criterion (neither stress nor strain), e.g. fracture energy Gf
to obtain the same damage (merging force/ disp. based criteria
-earthquake structural response: nonlinear dynamics & damping
Material vs. structure: probability
Génie Civil et Environnement
Benchmark EDF
Computed results
Delaplace, Ibrahimbegovic [2006] IJNME, Brancherie, Ibrahimbegovic [2009] EC
Mazars E E (1-d) ; d € [0,1]
Questions (… with no answer in year 2000):
-prediction of complex crack patterns with proper nature of dissip.vol./surf. ?
-multi-physics extension of failure description ?
Nooru-Mohamed, TU Delft
experiment
Material vs. structure: probability
Benchmark EDF
Result : phenomenological models
are neither sufficiently robust
nor predictive under
non-propor. loading
- - - - - - - - - - - - - - - - - -
Guiding principles for model construction:
-separate complexities: to each mechanism its own criterion
-real nature of dissip. In fracture prob. volume vs. surface
-const. law «only» not enough : must address «FEM» issues
-model parameters in dynamics – related to fracture energy (Gf)
Material vs. structure: probability
Material vs. structure: probability
1st class of problems: Structural point of view
micro-macro dedicated representation of
inelastic fracture of a massive structure without
detailed representation of damaged zone
“Macro” crack accompanied by large fracture process zone
Material vs. structure: probability
+ condition of stress orthogonality
multi-scale interpretation:
total dissipation additive
Ibrahimbegovic, Brancherie [2003] CM, ‘”Crisfield issue”
Original approach
Failure of massive structures
Localisation problem:
σ = cst.
Gf
Material vs. structure: probability
D. Brancherie, A. Ibrahimbegovic [2009] Eng. Comp.
Gf
in Dynamics:
Damage model is not enough
no residual deformation need coupled
damage-plasticity:
s
Ce
D-1
e = ep + ed + ee
A. Ibrahimbegovic, D. Markovic, F. Gatuingt [2009] REEF
Material vs. structure: probability
-model criteria: plasticity + damage + localization
-internal variables: plasticity + damage + localization
Material vs. structure: probability
-model parameter identification procedure: plasticity + damage + localization
Material vs. structure: probability
-coupled damage plasticity model
representing 3 phase response:
evolution equations: operator split
-experimental vs. numerical results
A. Ibrahimbegovic, P. Jehel, L. Davenne [2008] Computational Mechanics
P. Jehel, A. Ibrahimbegovic, P. Leger, L. Davenne [2009] Concrete. Comp.
Material vs. structure: probability
-linear hardening model
additive structure of compliance
for computational robustness
(no need for local iterations) !
Very robust computational model
(FULLY IMPLICIT CODE
result quality guaranteed ! )
Material vs. structure: probability
-stress-strain loop: softening damage vs. hardening damage
-time history: i) loading, ii) displacement, iii) force-displacement
Material vs. structure: probability
23
Reinforced concrete frames is the most widely
used material in civil construction.
Structural designs apply standard design codes:
EC2, UK code, BS8110, ACI 318 with different
limitations in concrete and steel material.
Standard design procedures: 1- Linear analysis
(moment, shear , axial force); 2- Ultimate analysis
for cross-section(reinforcement area and stirrup); 3-
Then check other conditions ( deflection, buckling,
cracking)
23Idea: Stress-Resultant models for efficient comput. and design reinforced concrete frames
Reinforced concrete structures: standard vs. performance based design
This is “true” plastic hinge !
Material vs. structure: probability
24
2- Semi-global
3- Local model
Multi-layer model
(Pham, Davenne, Brancherie , Ibrahimbegovic [2010]
CC)
Moderate computational effort
2D model predicting crack spacing
,(Ibrahimbegovic, Boulkertous, Davenne [2010\
IJNME)
Large computational effort
3
Stress-resultant models for RC frame structures performance-based design
1D stress-resultant model for truss / beam failure
(Ibrahimbegovic, Brancherie [2003] CM,
Pham, Brancherie, Ibrahimbegovic [2010] CM)
Efficient computations
1- Global level
Material vs. structure: probability
able to capture the size effect ?
2nd class of problems: Material point of view:
interpretation of inelastic behavior mechanisms through
multi-scale analysis at strongly coupled scales
of 3 pt. bending test
Goal: predict material response from finer scales !
Material vs. structure: probability
Typical test :
3-pts. bending
Multi-scale model:
uM – macroscale displacement
um,e - microscale displacement
ξm - internal variables
Πa - energy
a=M strain energy at macroscale
a=m strain energy at microscale
a=interface scale coupling condition
a=ext external force energy
Model problem:
2 phase material
(porous media)
Material vs. structure: probability
-color code: matrix – blue, inclusions – green, interface -
red
Current works: 3D microstructure representation
Voronoi cell representation + cohesive forces
(Benkemoun, Hautefeuille,Colliat, Ibrahimbegovic [2010] IJNME)Material vs. structure: probability
Example: Simple tension test
force-displacement diagrams / contours of displacement / broken bars
- result invariance: mesh objectivity / isotropy
Material vs. structure: probability
Uni-axial compression test
Biaxial compression test
Cracks: Biaxial vs. Simple Comp. Test
Material vs. structure: probability
Tension test
– 2D repres.
of porous
material
a) Non-structured FE mesh b) Structured FE mesh(similar nb. FE in each mesh, but elements in mesh a) distorted + node numberiing)
(Hautefeuille, Melnyk, Colliat, Ibrahimbegovic [2009] EC)
Statistics of computed response
Mean response + st. dev.
Porosity histogram / f-u realizations
Heterogeneities !H. Matthies[2006]
, NATO-ARW
Computed diagram:
Force-imposed displacement
--- non-structured FE mesh [CPU time: 11774 s]
--- structured FE mesh [CPU time: 646 s]
Heterogeneity, probabilistic description and size effect:
Material vs. structure: probability
• chosen Lc = 0,01 m
(Matthies [2007])
Error in covariance repres. with: 5, 10, 50 KL modes + exact
Heterogeneity, probabilistic description and size effect:
Material vs. structure: probability
(Colliat, Hautefeuille, Ibrahimbegovic, Matthies [2006] CRAS)
Distribution of max force -
Fractals at 10%:
Short 3.35 MN
Medium 2.90 MN
Long 2.70 MN
Conclusions:
1. Lc introduces the notion of scale
2. Quasi-fragile mater. size effect !
3. Extension of “weak link” (Weibull [1951]
Bazant [1995]
Heterogeneity, probabilistic description and size effect:
Material vs. structure: probability
Chaire de Mécanique « PICARDie »
Lecture outline:
1. Resilience quantification = system of systems
2. Material vs. structure: probability aspects
3. Combined extreme loading conditions
(earthquake, tsunamis, explosions, fires)
4. Conclusions
Pr Adnan Ibrahimbegovic
Tsunami risk map
Failure of Tacoma Bridge (US) under
wind excitation in 1940
Structural Vulnerability has many other facets
Combined extreme loads
FSI (existing) software coupling Open-FOAM + FEAP (no com. codes !)
-Nested parallelization
Remark:
-other codes
(e.g. Chaire ESI ?)
Kassiotis, Ibrahimbegovic, Niekamp,
Matthies [2011] Comp. Mech.
Combined extreme loads
Combined extreme loads
37
2004 Sumatra, Indonesia, Earthquake 2011 Eastern Japan Earthquake
Tsunami can bring other concurrent hazards (fires, landslides, industrial disasters, etc.)
Getty Images
Structural Vulnerability has many facets:
tsunamis + fires
Tsunami risk map
Combined extreme loads
38
Structural Vulnerability has many facets:
terrorist attack + fires
The Murrah
Federal Building
(Oklahoma City)
before and after
the car bomb
attack of 1995
World
Trade
Center,
Sept 11
Problem: projectile impact
(e.g. nuclear power plant,
storage bldg.) ?
CEA: Dept. Military Appl.
Combined extreme loads
39
39
Previous design: impact by “small’ plane, Cesna
(commercial plane P(impact) < 1e-07)
g*
Ibrahimbegovic, Herve, Villon, Eng. Comp. [2009]
Airplane impact on massive struct. (CEA/ Dept. Applications Militaires)
Proposed refined design: Hard vs. Soft impact + field transfer
• 1D model projectile (mass+spring)
• Angle of impact = 90° response spectrum
• Target infinitely rigid
Combined extreme loads
Finite rotation shell model (large rotations, shell instability)
… A. Ibrahimbegovic et al. [1994, 1997,2001] CMAME, ASME-AMR, IJNME
u = 4[mm] u = 5[mm] u = 6[mm]
Viscoplasticité
Sheet metal forming
Large strain plasticity (large strain plasticity, necking instability)
… A. Ibrahimbegovic et al. [1994, 1999, 2000] IJSS, CMAME, CS
Research Expertise: 3D Finite Def. Plasticity
FEAP
UC Berkeley
Zienkiewicz & Taylor
[2005] Elsevier
Combined extreme loads
Multiphysics: Structural Vulnerability has many other facets
41
WTC, September 11/01
Combined extreme loads
: Dujc, Brank, Ibrahimbegovic, CMAME [2010]
Steel structures
Combined extreme loads
Localized failure – finite strain plasticity thermo-mechanical
coupling
Example: Mesh Objectivity
L1 =1m, A =1mm2 θ = 100t
U = 0
θ = 0
u = 2t (mm)
Material Properties Value Dimension
Young modulus 205000 MPa
Initial yield stress 250 MPa
Ultimate stress 300 MPa
Plastic hardening modulus 20000 MPa
Localized softening modulus -45 MPam-1
Mass Density 7.865 10-9 Ns2mm-4
Thermal conductivity 45 N s-1K-1
Heat specific 0.46 109 mm2s-2K-1
Thermal elongation 0.00001
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
50
100
150
200
250
300
- 5 elements
Force (N)
Displacement (mm)
+ 7 elements
* 9 elements
0 0.0020.0040.0060.008 0.01 0.0120.0140.016
50
100
150
200
250
300
Displacement (mm)
Force (N)Temperature independent properties
Temperature dependent propertiesMaterial properties
Temp. dependence (EC 1993)
Ngo, Ibrahimbegovic, Brancherie [2014] Coupled Systems Mechanics
Combined extreme loads
12/2/2015Localized failure for thermo-
mechanical problem44
Truss Instability at Finite Deformation
0 0.1 0.2 0.3 0.4 0.5 0.6-10
010
20
30
40
50
60
Displacement (m)
Force (kN)
Thermo-mechanical loadingMechanical loading
Temperature Distribution in the Truss before collapse
Case 1 Case 2Load/displacement curve
Combined extreme loads
Lecture Outline :
1. Resilience quantification = system of systems
2. Material vs. structure: probability aspects
3. Combined extreme loading conditions
(earthquake, tsunamis, explosions, fires)
4. Conclusions
Chaire de Mécanique « PICARDIE »
Pr Adnan Ibrahimbegovic
Chaire de Mécanique « PICARDIE »
MONOGRAPHS/
TEXTBOOKS :
… Springer 2009
… Hermes / Lavoisier 2006
… Springer 2008(AI, M. Zlatar)
… Springer 2007(AI, I. Kozar)
Perspectives for Resilience Studies: System vs. Structure !
Studies at the scale of complex structure
currently needed for sensitive structures (nuclear)
Objectives: Crack patterns (spacing, opening)
=> fluid flow through cracks, durability
Multi-physics / Multi-phenomena
Structures of large size
=> Multi-scale analysis (space and time)
and code coupling
Uncertainties
Probabilistic analysis
Conclusion: the biggest European computer
(with CEA / DAM used for nuclear simulations)
will also be used for earthquake simulations !
Conclusions
Perspectives for Resilience Studies: System vs. Structure !
Studies at at scale of (mega-) cities
Complex systems with different interactions
vert.
trans.
long.
Macro-elements:
piping, soil, joints
Echelle du quartier
Interaction sol-structures
Fragility curves
scenarios
Probabilistic comp.
Population in urban areas :
1950 : < 30%
2010 : 50%
2030 : > 60%
Conclusions
Perspectives for Resilience Studies: System vs. System of systems !
Conclusions
Gracias por su atención.
Thank you for your attention.
Merci bien de votre attention.