From Theory to Practice: Performance-based Kinematic Pile Response - Kevin Franke

Kevin W. Franke, Ph.D., P.E.
Assistant Professor, 2011-2012 EERI/FEMA NEHRP Graduate Fellow
Department of Civil and Environmental Engineering
Brigham Young University, Provo, Utah
2013 EERI Annual Meeting
Seattle, WA USA
February 14, 2013

Kevin W. Franke, 2011-2012 EERI/FEMA NEHRP Graduate Fellow Feb 14, 2013

Goals of our Research:
 Develop a PB procedure to compute kinematic pile
response due to free-field lateral spread displacement
 Incorporate empirical lateral spread models, but be
flexible enough to utilize other methods if desired
 Utilize commonly-used pile response software (e.g.
LPILE)
 Revisit and develop five “forgotten” kinematic loading
case histories from Costa Rica
 Make inferences based on comparisons between the
PB results and observed kinematic pile response from
the case histories.

Lateral Spreading

after Varnes (1978)

(after Varnes (1978)
Port in Port-au-prince, Haiti following 2010 EQ


Lateral Spreading

Down Slope
Movement


Performance-based Kinematic Pile
Response Procedure
 DV   G DV DM dG DM EDP dG EDP IM d  IM

 Intensity Measure – lateral spreading loading
parameter, L (after Franke 2005, Kramer et al. 2007)
 Engineering Demand Parameter – lateral spreading
displacement
 Damage Measure – kinematic pile response


Response Procedure
Develop hazard curves for lateral spread displacement using
empirical models using Franke (2005) and Kramer et al. (2007)
procedure.
Ni
d   P  DH  d | L i , S    L 
i 1


Response Procedure
Given a lateral spread displacement vector, use a kinematic pile
response model to compute mean pile response and to
characterize uncertainty in soil/pile interaction
Pile Displacement (m) Shear Force (kN) Bending Moment (kN-m) Curvature (rad)
-0.5 0 0.5 1 1.5 2 2.5 3 -2000 -1000 0 1000 2000 -1000 0 1000 2000 -0.4 -0.2 0 0.2
0
1. Point estimate methods
2. First order second 2

moment methods 4
Depth Below Pile Head (m)

3. Monte Carlo methods 6

Pile response 8

 R  R 
P  R  R   1  



 10

  R|DH 
  12

14


Response Procedure
At the depth of interest, compute the mean annual rate of
exceeding R  as: Lateral Displacement

N DH

Depth
1m at depth = 0

 R   P  R  R | DH  D



 H ,i
i 1 Lateral Displacement

Depth
Could develop similar 2m at depth = 0
Mean Annual Rate of

plots for bending
Exceedance

moment, shear force, Lateral Displacement

or curvature!

Depth
3m at depth = 0

1 2 3 4
Lateral Displacement at the Pile Head
(m)


Response Procedure
By performing across all depths of the pile, uniform hazard
pile response profiles can be developed


Costa Rica Limon Earthquake
• April 22, 1991 – M7.6
• Killed 53 people
• Injured 193 people
• Disrupted ~30% of
highways in the Limon
Province


Costa Rica Case Histories


Rio Cuba Bridge
• Reinforced Concrete bridge
• Constructed in the late
1960’s
• 3-spans, each 22 meters in
length
• Each abutment supported
by fifteen 14-inch square
RC piles that are 14 meters
in length
• 30° skew at abutments
• Approach embankments are
approximately 6 meters high


Rio Cuba Bridge
• Bridge deck did not
collapse, but “pinned” the
abutments
• Cracked piles are still
exposed
• Rotations still visible (8.5°
at the east abutment)
• All visible evidence of
lateral spread is gone, but
back-calculation suggests
that soil displacements
were approximately 0.35
meter


Rio Cuba Bridge Lessons Learned
• Deterministic empirical
lateral spread models
computed average
displacement of 0.27 meter
(within 31% of back-
calculated displacement).
• Bridge deck did not
collapse, but “pinned” the
abutments.
• The bridge deck appears to
govern the behavior of the
kinematic pile response.

Free (No Bridge Deck) Pinned (Bridge Deck)

Rio Bananito Highway Bridge
(Original Bridge)
• Reinforced concrete bridge
• Constructed in the 1971
• 2-spans, each ~27 meters in
length
• South abutment supported
by nine 14-inch square RC After Priestley et al (1991)

piles that are 15 meters in
length (Bridge Today)
• 30° skew at abutments
• Approach embankments are
approximately 3 meters high


Rio Bananito Highway Bridge
• Bridge deck collapsed
following massive soil
deformations (3.5 - 5.1 meters)
• Piles and abutment were
rotated 14 degrees and
translated 3.9 meters
• Post-seismic slope stability
analysis suggests this event
was likely a flow failure
• Eye-witness account reports
that the deck stayed in place
for approximately 1 minute; After Youd et al.
(1992)
after it collapsed, the entire
abutment slid into the river


RB Highway Bridge Lessons Learned
• Deterministic empirical
lateral spread models
computed less than half of
measured displacements.
• Again, the importance of the
bridge deck in determining
pile response is
demonstrated.
• A deterministic 2-stage
calculation successfully
replicated the horizontal
pile/abutment deformations
at the south abutment.


Rio Bananito Railway Bridge
• Steel truss rail bridge
• Constructed prior to 1890
• single-span 48 meters in
length
• Each abutment supported
by two 1.5m x 2.2m
elliptical CISS caissons
• Dynamic wave equation
analysis of exposed
caissons suggests they are
12 meters in length
• Little to no approach
embankments


Rio Bananito Railway Bridge
• Lateral spreading pushed all four
caissons towards the river (between
0.5 to 5.7 meters, rotations of 26°-
37°) and unseated the bridge at
both abutments.
• Bridge tilted to the east 15 degrees,
but amazingly did not collapse.
• Lateral spread displacement of over
4 meters was measured in the free-
field at the north abutment. Photos after Youd (1993)

• Dynamic wave equation analysis
indicated significant caisson
damage at a depths between 8-9
meters


RB Railway Bridge Lessons Learned
(Deterministic) (Performance-Based)
• Average empirical lateral spread
displacement at the north abutment
was 2.6 meters, which under-
predicted observed displacements.
• Traditional pile response methods
using p-y analysis in LPILE
reasonably replicated the observed
pile response of a single caisson.
• Maximum moment was computed to
occur between depths of 8-9 meters.
• PB analysis showed that the actual
kinematic pile response
corresponded to Tr=560 years.
(AASHTO currently targets Tr=1,033
years).


Rio Estrella Bridge
• 3-span steel and pre-
stressed concrete bridge
that is 178m in length
• Constructed in 1971
• South abutment is
supported by 2 bent-style
pile caps, each founded on
24 H-piles
• Surficial topography
around the bridge is
constantly changing due to
the river and the “banana
wars”


Rio Estrella Bridge
Courtesy of EERI
• The two steel truss spans collapsed
during earthquake shaking.
• Significant liquefaction and lateral
spread observed in the vicinity of
the southern abutment. Up to 2
meters of lateral displacement was
estimated.
• The approach embankment to the Courtesy of
LIS, Universidad de
southern abutment experienced Costa Rica

extensive localized, transverse
slope stability failures.
• Amazingly, the abutment itself was
not moved despite the kinematic
chaos around it. We wanted to find
out why.


Rio Estrella Bridge Lessons Learned
• Empirical lateral spread models
(No Water Film) (Water Film)
significantly underpredicted (0.4m) the
observed displacements at the southern
abutment (~2m).
• Our analysis suggests that the pinning
effect of the piles was not sufficient alone to
keep the foundation from moving.
• The soil stratigraphy at the site supported
the theory that a water film may have
developed above the pile caps, thus
isolating the pile caps from the bulk of the
kinematic loading.
• For similar scenarios, similar innovative
foundation design might help reduce
potential damage to foundations from
kinematic loading.


Conclusions
1. A performance-based kinematic pile response procedure
was successfully developed.
 Based on empirical lateral spread displacement models
 Soil-pile interaction can be computed with commonly-used
software such as LPILE
 Useful for evaluating the return period associated with various
levels of kinematic pile response
2. New lateral spread/kinematic pile response case
histories from the 1991 Limon EQ in Costa Rica were
brought to light.
3. For these cases, empirical lateral spread models
generally under-predicted the observed displacements.


Conclusions
4. For bridges, the presence of the bridge deck plays a
major role in the kinematic response of the piles,
even for simply-supported abutments.
5. The development of a water film can isolate the
majority of the lateral displacements to a relatively
thin zone.
6. For certain applications, placing the pile cap within
or below the liquefiable layer may reduce
foundation damage due to kinematic loading.


Acknowledgements
 This study was funded by a grant from the US
Geological Survey External Research Program (No.
G10AP00047)
 The Costa Rica Ministry of Transportation
 Prof. Kyle Rollins (BYU)
 Prof. T. Leslie Youd (BYU)
 Prof. Steven Kramer (UW)
 EERI/FEMA
 My wife Ruby and our 5 beautiful children


Thank you!

Kevin W. Franke, Ph.D., P.E.
Assistant Professor, 2011-2012 EERI/FEMA NEHRP Graduate Fellow
Department of Civil and Environmental Engineering
Brigham Young University, Provo, Utah
2013 EERI Annual Meeting
Seattle, WA USA
February 14, 2013


From Theory to Practice: Performance-based Kinematic Pile Response - Kevin Franke

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From Theory to Practice: Performance-based Kinematic Pile Response - Kevin Franke