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Peter Sheffield & Associates Ltd.
Peter Sheffield & Associates Ltd.
Micropile Bearing Plates: Are they Necessary? Presented by: Nadir - - PowerPoint PPT Presentation
Micropile Bearing Plates: Are they Necessary? Presented by: Nadir - - PowerPoint PPT Presentation
Micropile Bearing Plates: Are they Necessary? Presented by: Nadir Ansari, P.Eng. Peter Sheffield & Associates Ltd. The Art Gallery of Ontario Peter Sheffield & Associates Ltd. Post-Transformation Frank Gehry Peter Sheffield &
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Peter Sheffield & Associates Ltd.
Post-Transformation – Frank Gehry
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Peter Sheffield & Associates Ltd.
Royal Ontario Museum
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Peter Sheffield & Associates Ltd.
Post-Transformation - Daniel Libeskind
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Peter Sheffield & Associates Ltd.
- Reasons for Test
- Test set up
- Instrumentation
- Our Findings
Outline
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Peter Sheffield & Associates Ltd.
Reasons for Test and Analysis Program
- Cost
- Time/ Schedule impact
- Difficult to ensure plate to grout contact
- Plates impede concrete placement beneath
- Plates provide smooth interface where
cracks may propagate
- Tests by the Ohio DOT in 1947, suggest
large plates may weaken pile caps
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Peter Sheffield & Associates Ltd.
Test Set Up
Dial Gauges Air Pocket
1000 mm 1800 mm 800 mm 1200 mm Area of micropile Is 0.0294 m^2
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Test Set up
Dial Gauges
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Test Set Up
Concrete Strain Gauge Rebar with Strain Gauges
Compressible Material
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Test Set Up
Cylinders 30 MPa Concrete
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Cyclic Loading for One Micropile
LT1- Micropile Compression Test
500 1 000 1 500 2000 2500 3000 3500 4000 4500
5 1 1 5 20 25 30 35 40 45 50 55
Movement (mm) Load (kN)
- 8050 kN ultimate load on cap
- 50 mm movement
- 136 MPa based on MP area
- 2.33 Design Load
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Peter Sheffield & Associates Ltd.
Results - Actual Cracking Pattern
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Actual Cracking Pattern
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Cracking Pattern in
- ne quarter
- f the
cap
Column Base Plate
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Peter Sheffield & Associates Ltd.
Strut and Tie Model Used to Determine Required Reinforcement
Compression Strut Tension Tie A1 A2
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Vertical Stress
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Vertical Stress
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Horizontal Stress in Reinforcement Plane
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Results- Rebar Stress
- 30
- 25
- 20
- 15
- 10
- 5
5 1 2 3 4 5 6 7 8 9 10 Load (1000 kN) Stress (MPa) Test Analytical
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Peter Sheffield & Associates Ltd.
Our Findings
- Bearing plates were not necessary
- Based on area the bearing strength was 4.5
times the concrete compressive strength much higher than allowed by codes
- Class A analysis predicted failure within 5%
- The concrete strut was parabolic, not linear
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Peter Sheffield & Associates Ltd.
Findings Continued
- Longitudinal rebar was in Compression in the
middle of the pile cap
- Rebar can be spaced evenly across pile cap
- Further research for other geometries is
necessary
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Peter Sheffield & Associates Ltd.