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Bridge%20Pier%20Analysis%20and%20Design

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Title: Bridge%20Pier%20Analysis%20and%20Design


1
Soil Pile Group Interaction in FB-MultiPier
Dr. J. Brian Anderson, P.E.
Developed by Florida Bridge Software Institute
2
Session Goals
  • Soil-Pile Group Interaction
  • Discussion of Soil Strucuture Interaction Model
  • Lateral p-y multipliers
  • Axial efficiency factors
  • Example 2 Pile Group Analysis Load Test at
    Roosevelt Bridge

3
Coupled Soil-Structure Interaction
Ship Impact
4
Typical Deep Foundations
5
Soil-Structure Interaction
Vertical Nonlinear Spring
Torsional Nonlinear Spring
Lateral Nonlinear Spring
Nonlinear Tip Spring
6
Single Pile Model
7
Lateral Soil-Structure Interaction
Y
Active State
Passive State
8
Soil-Pile Group Interaction
Lead Row Smallest Disturbance
9
Soil-Pile Group Interaction
P
P x Pm2
P-y curves
P
P x Pm1
P-y curves
Group Interaction Modeled with Multipliers
10
Soil-Pile Group Interaction - Lateral
P-Multipliers
BROWN REESE (1988)
R
R
R
I
II
III
- Multipliers, Pm for P Values in P-y Curves
- Function of Row Position in Group
ROW Pm
R 0.8
I
R 0.4
II
Static
R 0.3
Ship Load
III
Pm would be 0.3 for R or greater
IV
11
Soil-Pile Group Interaction - Axial
  • Axial Efficiency

Summing Effects of a Friction Pile Group (FHWA)
12
Soil-Pile Group Interaction - Axial
  • Axial Efficiency

Block Failure Mode of Piles in Cohesive Soils
(FHWA)
13
Experiments
  • Scale Cenrtifuge Models (UF)
  • Plumb and battered pile groups
  • Embedded caps
  • Full Scale
  • Roosevelt Bridge Lateral Load Test (UF)
  • Axial Group Study (UH)

14
Centrifuge Modeling
Field
1 ft
Centrifuge
50 g
50 ft
Same Soil Stresses
15
Full Scale Load Test at Roosevelt Bridge
16
Roosevelt 4x4 Field Study
17
Prediction of Field Response
DEFLECTION (IN)
18
Single vs. Group Axial Behavior
FHWA Houston Study
25 ft
clay
18 ft
Sandy clay
Total Group
Individual Group Axial
Single Axial
19
Experimental Results Plumb Piles
  • Efficiencies and multipliers are independent of
    soil density
  • Group Efficiencies
  • At 5D Spacings - 95
  • At 3D Spacings - 70 to 75
  • Lateral Multipliers
  • At 3D Spacing- 0.8, 0.4, 0.3, 0.2, 0.2,,0.3
  • At 5D Spacing- 1.0 , 0.85, 0.7,..,0.7

20
Experimental - Battered Piles
  • Efficiencies and multipliers are independent of
    soil density
  • Lateral Multipliers
  • At 3D Spacing- 0.8, 0.4, 0.3, 0.2, 0.2,,0.3
  • At 5D Spacing- 1.0 , 0.85, 0.7,..,0.7
  • Data Available only for A frame design

21
Pinned Laterally Loaded Pile Group
22
Fixed Head Laterally Loaded Group
23
Design Summary
  • Pile Group response is strongly influenced by
    geometry, loading, connectivity, material
    characterization
  • geometry 3D vs. 5D, battered vs. plumb
  • connectivity fixed vs. pinned pile heads
  • loading lateral or combined lateral axial
  • material linear vs. nonlinear pile models

24
References
  • Zhang, L.M., McVay, M.C., Han, S.J., Lai, P. and
    Gardner, R., Effects of Dead Loads on the
    Lateral Response of Battered Pile Groups,
    Canadian Geotechnical Journal, Vol. 39, No. 6,
    June 2002, pg. 188-203.
  • McVay, M.C., Zhang, L., Molnit, T., Bollmann, H.,
    and Lai, P., Centrifuge Testing of Large Plumb
    Pile Groups (3x3 To 7x3) in Sands, ASCE, Journal
    of Geotechnical Engineering, Oct. 1998, Vol. 124,
    No 10, pp. 1016-1026.
  • Zhang, L., McVay, M.C., and Lai, P., Numerical
    Analysis of Fixed Head 3x3 to 7x3 Plumb Pile
    Groups in Sands, ASCE, Journal of Geotechnical
    Engineering, Nov, 1999, Vol. 125, No. 11, pp.
    936-946.
  • Brown, D, Morrison, C., and Reese, L. Lateral
    Load Behavior of a Pile Group in Sand, ASCE,
    Journal of Geotechnical Engineering, 1988, Vol
    114, No. 11, pp. 1261-1276
  • McVay, M.C., Zhang, L., Han, S., and Lai, P.,
    Experimental and Analytical Modeling of
    Laterally Loaded Pile Groups with Embedded Pile
    Caps in Sand, Transportation Research Record,
    No. 1736, Dec. 2000, pp. 12-18.
  • Pinto, P. and McVay, M.C., Hoit, M., and Lai, P,
    Centrifuge Testing of Plumb and Battered Pile
    Groups in Sand, Transportation Research Record,
    No. 1569, Jan. 1997, pp. 8-16.
  • O'Neill, M. W., Brown, D. A., Anderson, D. G., El
    Naggar, M. H., Townsend, F. C., Mcvay, M. C.
    (1997). Static and dynamic lateral loading of
    pile groups. NCHRP 24-9, Highway Research
    Center, Harbert Engineering Center, Auburn
    University, Auburn, AL

25
Session Goals
  • Soil-Pile Group Interaction
  • Discussion of Soil Strucuture Interaction Model
  • Lateral p-y multipliers
  • Axial efficiency factors
  • Example 2 Pile Group Analysis Load Test at
    Roosevelt Bridge
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