Seismic evaluation of prestressed and reinforced concrete pile wharf deck connections
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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

Seismic Evaluation ofPrestressed and Reinforced ConcretePile-Wharf Deck Connections

Jennifer Soderstrom

University of Washington


Introduction
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



Pile deck connections
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


Prototype connections
Prototype Connections

  • Survey of Wharves in Los Angeles, Oakland and Seattle

  • Connection types used included:

    • Precast Pile Connection

    • Pile Extension Connection

    • Batter Pile Connection


Precast pile connection
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


Pile extension connection
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


Pile section
Pile Section

  • 24 in octagonal prestressed pile most common

  • Details varied


Test methodology
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







Testing procedure
Testing Procedure

  • Modified ATC-24 loading sequence

  • Lateral displacement from 0.05% to 10.6% drift

    % drift = lateral deflection / pile length


Experimental results
Experimental Results

  • Test observations

  • Force-deflection history

  • Moment-curvature history

    • Average curvature

    • Strain curvature

  • Strain distribution

  • Incremental strain distribution


Test observations pile cracking
Test Observations – pile cracking

1

2

3

4

Cracking at 1.0% drift


Test observations deck cracking
Test Observations – deck cracking

Specimen 1

Specimen 3

Specimen 2




Force deflection history specimen 1
Force-Deflection History – specimen 1

Peak load = 26.5 kips at 4.5% drift


Force deflection history specimen 3
Force-Deflection History – specimen 3

Peak load = 30.7 kips at 3.0% drift


Force deflection history specimen 4
Force-Deflection History – specimen 4

Peak load = 38.1 kips at 1.5% drift


Moment curvature history
Moment-Curvature History

Average curvatures

  • Calculated over intervals 0 to ½ diam. and ½ to 1 diam.


Moment average curvature
Moment-Average Curvature

  • Specimen 1

  • Lower curvature 2-3 times greater than upper curvature

½ to 1 diam. (upper)

0 to ½ diam. (lower)


Moment average curvature1
Moment-Average Curvature

½ to 1 diam. (upper)

0 to ½ diam. (lower)

  • Specimen 4

  • Lower curvature 8-10 times greater than upper curvature


Moment curvature history1
Moment-Curvature History

Strain curvatures

  • Calculated at distances of 8.25, 0 and –5 in from interface


Moment strain curvature
Moment-Strain Curvature

  • Specimen 2

  • Strain curvatures highest in pile section

8.25 in

interface

-5 in


Moment strain curvature1
Moment-Strain Curvature

8.25 in

interface

-5 in

  • Specimen 4

  • Strain curvatures highest in deck


Strain distribution
Strain Distribution

Specimens 1, 2

  • Peak strains between interface and ½ diameter

  • Yield at 1.0% drift


Strain distribution1
Strain Distribution

Specimen 3

  • Peak strains in deck, 5 in below interface

  • Yield at 0.75% drift

  • High strains in lower bar


Strain distribution2
Strain Distribution

Specimen 4

  • Peak strains in deck, 5 in below interface

  • Yield at 1.0% drift


Incremental strain distribution
Incremental Strain Distribution

  • D Strains at 1000 kip-in moment, first cycles

  • Exponential distribution indicates good bond

Specimen 2

Good bond within deck


Incremental strain distribution1
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


Conclusions
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%


Conclusions1
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


Conclusions2
Conclusions

  • The addition of spiral reinforcement in the

  • joint region did not appear to have a

  • significant effect on pile extension

  • performance


Seismic evaluation of prestressed and reinforced concrete pile wharf deck connections1

Seismic Evaluation ofPrestressed and Reinforced ConcretePile-Wharf Deck Connections

Jennifer Soderstrom

University of Washington


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