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Seismic Evaluation of Prestressed and Reinforced Concrete Pile-Wharf Deck Connections

Seismic Evaluation of Prestressed and Reinforced Concrete Pile-Wharf Deck Connections. Jennifer Soderstrom University of Washington. Introduction. Ports represent a large economic investment for a region Direct damage to the port of Kobe, Japan estimated to exceed U.S.$11 billion

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Seismic Evaluation of Prestressed and Reinforced Concrete Pile-Wharf Deck Connections

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  1. Seismic Evaluation ofPrestressed and Reinforced ConcretePile-Wharf Deck Connections Jennifer Soderstrom University of Washington

  2. Introduction • Ports represent a large economic investment for a region • Direct damage to the port of Kobe, Japan estimated to exceed U.S.$11 billion • It is worthwhile to evaluate the seismic performance of port facilities

  3. Typical Wharf Section

  4. Pile-Deck Connections • Piles are the sole supports for large gravity loads • Detailing must be sufficient to allow pile forces to develop and hinges to form • Repair and inspection can be difficult, so a connection should remain undamaged in a large seismic event

  5. Prototype Connections • Survey of Wharves in Los Angeles, Oakland and Seattle • Connection types used included: • Precast Pile Connection • Pile Extension Connection • Batter Pile Connection

  6. Precast Pile Connection • Most common connection was a 24 in octagonal prestressed pile • Pile set 2 in into deck • Hooked dowels grouted in pile ducts • Varying development lengths

  7. Pile Extension Connection • Cast prior to deck if length > 6 in • Hooked dowels grouted in pile ducts and passing through extension • Varying development lengths • Extended spiral in some connections

  8. Pile Section • 24 in octagonal prestressed pile most common • Details varied

  9. Test Methodology Connection types investigated in this study: • Pile Extension Connections • No spiral reinforcement in joint region • Moderate spiral reinforcement in joint region • Precast pile connections • No axial load • 222 kip axial load

  10. Specimen 1: Pile Extension

  11. Specimen 2: Pile Extension w/Spiral

  12. Specimens 3&4: Precast Pile

  13. Test Setup

  14. Axial Load System

  15. Testing Procedure • Modified ATC-24 loading sequence • Lateral displacement from 0.05% to 10.6% drift % drift = lateral deflection / pile length

  16. Experimental Results • Test observations • Force-deflection history • Moment-curvature history • Average curvature • Strain curvature • Strain distribution • Incremental strain distribution

  17. Test Observations – pile cracking 1 2 3 4 Cracking at 1.0% drift

  18. Test Observations – deck cracking Specimen 1 Specimen 3 Specimen 2

  19. Test Observations – end of tests 1, 2 Specimen 2 Specimen 1

  20. Test Observations – end of tests 3, 4 Specimen 3 Specimen 4

  21. Force-Deflection History – specimen 1 Peak load = 26.5 kips at 4.5% drift

  22. Force-Deflection History – specimen 3 Peak load = 30.7 kips at 3.0% drift

  23. Force-Deflection History – specimen 4 Peak load = 38.1 kips at 1.5% drift

  24. Moment-Curvature History Average curvatures • Calculated over intervals 0 to ½ diam. and ½ to 1 diam.

  25. Moment-Average Curvature • Specimen 1 • Lower curvature 2-3 times greater than upper curvature ½ to 1 diam. (upper) 0 to ½ diam. (lower)

  26. Moment-Average Curvature ½ to 1 diam. (upper) 0 to ½ diam. (lower) • Specimen 4 • Lower curvature 8-10 times greater than upper curvature

  27. Moment-Curvature History Strain curvatures • Calculated at distances of 8.25, 0 and –5 in from interface

  28. Moment-Strain Curvature • Specimen 2 • Strain curvatures highest in pile section 8.25 in interface -5 in

  29. Moment-Strain Curvature 8.25 in interface -5 in • Specimen 4 • Strain curvatures highest in deck

  30. Strain Distribution Specimens 1, 2 • Peak strains between interface and ½ diameter • Yield at 1.0% drift

  31. Strain Distribution Specimen 3 • Peak strains in deck, 5 in below interface • Yield at 0.75% drift • High strains in lower bar

  32. Strain Distribution Specimen 4 • Peak strains in deck, 5 in below interface • Yield at 1.0% drift

  33. Incremental Strain Distribution • D Strains at 1000 kip-in moment, first cycles • Exponential distribution indicates good bond Specimen 2 Good bond within deck

  34. Incremental Strain Distribution • D Strains at 1000 kip-in moment, specimen 3 • D Strains at 1500 kip-in moment, specimen 4 Specimen 3 Slip in top 5 in of deck Good bond in pile section

  35. Conclusions • All connections had large rotational capacities • Precast pile connections were initially stiffer • and stronger, but experienced greater • deterioration than pile extensions • A moderate axial load increased strength by • 25%, but caused greater deterioration at drift • levels above 2.0%

  36. Conclusions • Pile extensions dissipated more energy at high drift levels through continued flexural cracking, while damage in the precast connection was concentrated in large cracks near the interface • Precast pile connections experienced bond • slip and rocking in early load cycles

  37. Conclusions • The addition of spiral reinforcement in the • joint region did not appear to have a • significant effect on pile extension • performance

  38. Seismic Evaluation ofPrestressed and Reinforced ConcretePile-Wharf Deck Connections Jennifer Soderstrom University of Washington

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