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NUMERICAL SIMULATION OF URM INFILL WALLS in RC FRAMES: CRITICAL MODELING ASPECTS. KHALID m. mosalam UNIVERSITY OF CALIFORNIA, BERKELEY. Motivation. URM Infill Walls in RC Buildings Benefits S ignificant effects on functionality - PowerPoint PPT Presentation
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Prof. Khalid Mosalam University of California, Berkeley
NUMERICAL SIMULATION OF URM INFILL WALLS in RC FRAMES:
CRITICAL MODELING ASPECTS
KHALID M. MOSALAM
UNIVERSITY OF CALIFORNIA,
BERKELEY
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
Motivation
3
URM Infill Walls in RC Buildings Benefits
Significant effects on functionality Contribute to lateral force resisting capacity & damping up to a certain hazard
level Increase the overall stiffness – may have benefits for certain cases
Detrimental Effects Sudden brittle failure: High potential to form a soft story during shaking Interaction with the frame: Shear failure of columns In plane/out of plane interaction: Reduced capacity in both directions In plane/out of plane interaction: Debris from out of plane failure, life safety
concerns Torsional effects due to asymmetric wall arrangement in plan
Quantification of detrimental effects requires proper modeling
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
Motivation
4
Soft Story:Kocaeli EQ, Turkey, 1999 (left)Haiti EQ, 2010 (right)
In-plane /out-of-plane interaction:Wenchuan EQ, China, 2008
Frame-URM interaction:L’Aquila EQ, Italy, 2009
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
Critical Modeling Aspects
5
In-plane/Out-of-plane Interaction: General modeling
midspan node with OOP mass
Beam-column elements (frame members)
Beam-column elements (frame members)
beamWithhinges elements
X
Y
Z
Infill wall model
&
Inelastic fiber section
Elastic section
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
6
In-plane/Out-of-plane Interaction: Section discretization
Critical Modeling Aspects
M
P i = 1
i = 2 i
i+1
i = Npts
Pi-Pi+1
Mi+1-Mi
zi
y (local)
z (local)
Fiber 1
ith fiber with area Ai
PNA 1
PNA 2
Note: fiber areas and locations are symmetric with respect to the y-axis
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
7
URM infill removal upon failure
Critical Modeling Aspects
OOP displacement
IP d
ispl
acem
ent
Displacement history
Failure Curve (symmetricabout x and y axes)
Integration time step i-1 Integration
time step i
@Integration time step i
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
8
URM wall removal upon failure: Algorithm
Critical Modeling Aspects
OOP displacement
IP d
ispl
acem
ent
Displacement history
Failure Curve (symmetricabout x and y axes)
Obtain OOP displacement from the analysis (OOP analysis)
Obtain the IP displacement from the analysis (IP analysis) Check |IP analysis| IP limit
Activate removal for the infill wall (Remove beam-column elements and the middle node)
Yes No
Calculate the IP displacement from the interaction curve corresponding to the
absolute value of OOP analysis (IP limit)
Do not activate removal
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
9
Shear failure of columns
Critical Modeling Aspects
$nodemid $ele1
$ele2
$nodebot
$nodetop
Shear springs with nonlinear force displacement relationship
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
10
Rocking spine retrofit
Numerical Simulations For Retrofit
Courtesy of Tipping Mar, Berkeley
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
11
Rocking spine retrofit
Numerical Simulations For Retrofit
Courtesy of Tipping Mar, Berkeley
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
12
Rocking spine retrofit: Dynamic analysis with critical modeling aspects
Numerical Simulations For Retrofit
0
1
2
3
4
5
6
7
8
9
0 0.01 0.02 0.03 0.04 0.05Interstory Drift Ratio
Sto
ry #
As-builtRetrofit
Maximum inter-story drift profile
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
13
Numerical Simulations For Retrofit
Fragility curves
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.25 0.5 0.75 1 1.25 1.5PSa (g)
Prob
abili
ty o
f exc
eeda
nce
IDR = 0.01 As-builtIDR = 0.01 RetrofitIDR = 0.02 As-builtIDR = 0.02 RetrofitIDR = 0.03 As-builtIDR = 0.03 Retrofit
15WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
Rocking spine retrofit: Dynamic analysis with critical modeling aspects
Thank you
1415WCEE, Lisbon, Portugal, September 24-28, 2012Special Session 24.1 Seismic Retrofit of Masonry Structures. Monday, 24 September 2012
