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Soil Pile Group Interaction in FB-MultiPier

Soil Pile Group Interaction in FB-MultiPier. Dr. J. Brian Anderson, P.E. Developed by: Florida Bridge Software Institute. Session Goals. Soil-Pile Group Interaction Discussion of Soil Strucuture Interaction Model Lateral p-y multipliers Axial efficiency factors

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Soil Pile Group Interaction in FB-MultiPier

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  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. Live and Dead Loading Debris Impact Scour Scour Plumb Piles/Shafts Battered Piles Earthquake 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. Y Z  (F/L2)  (F/L2) P (F/L) P (F/L) Z Z Y Y P (F/L) Y  (F/L2) Z Single Pile Model

  7. P Y 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. LOAD-DEFLECTIONCURVE TEST PILE GROUP (MEASURED) FB-PIER PREDICTION ROOSEVELT BRIDGE - TEST PILE GROUP 1200 1000 800 600 LOAD (KIPS) 400 200 0 2 3 4 5 6 0 1 Prediction of Field Response DEFLECTION (IN)

  18. 3D 10.75” pipe 3D 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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