Non-Contact Measurements Pre-Stressed Concrete Beams

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A New Real-Time, Non-Contact Transfer-Length
Measurement Technique
Inventors
Dr. Terry Beck (Mechanical Engineering) Dr.
Robert Peterman (Civil Engineering) Dr. John Wu
(Industrial Engineering) Weixin Zhao (Industrial
Engineering)
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What is the problem for which you have a solution
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Why Measure Transfer Length?

• Used for calculation of shear capacity
• Used for calculation of stresses
• Has been shown to often be a good indicator of
  strand development length
• Could be used as a tool to screen out potentially
  poor-bonding mixes

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How is the problem being solved now?  Whats
wrong with current solutions?

• We simply dont measure it?

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Why Dont We Measure Transfer Length at the
Present Time?

• There is currently not a convenient or
  time-efficient method to get this information
• The current method(s) interrupt the daily casting
  and de-tensioning sequence

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Current Tool
Whittemore Gauge
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Strain in Pretensioned Concrete Member
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What is our solution?

• Non-Contact Measurements
• Portable as Current Tool
• Much Higher Precision
• More Flexible

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Concept of Laser Speckle
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Photograph of Laser Speckle on Concrete
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Peak Distances vs. Strains Measures
0.02mm deflection
0.10mm deflection
0.20mm deflection
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Actual experimental workwe have performed?
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Concrete beam cutting experiment
Prototype Design
Beam Cutting
Experiment Setup
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Cutting Pretensioned Specimen
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Comparison of Different Strain Gauges
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Prototype Specification
4?1/4 inches
8 in
Optical Sensor
Resolution lt 10me ? 1mm Weight 3
lbs Dimension 11x6x4 Measurement speed 15
samples/second
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Concrete Cylinder Compression Experiment
Optical Strain Gage
Electronic Strain Gage
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Concrete Cylinder Results
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Concrete Cylinder Results
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What is the closest prior art that might be cited
against the novelty of your invention?

• None !

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What Still Needs to Be Done?

• Continue to Gather SCC Mix Ingredients
• Cast Pretensioned Transfer-Length Specimens
  Members from 5 mixes used in SCC bond study
• Compare Whittemore Gage Results with Optical
  Results

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Additional K-State PersonnelHave Been Added

• Commercialization Manager.
• 2 MBA Students (Final Project).
• Product Design Engineer.
• 2 Other Design Engineers (Optics and Electrical).
• Precision Optical Measurements, Inc.

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The Goal

• Version 1 available for use this summer.
• For sale within one year (Approx. 20k)

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The Future
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Auto Measuring System
Measurement Surface
Sensor
Traverse
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Delta Strain Rosette
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Who specifically would be a possible commercial
partner or licensee for your invention?

• Precision Optical Measurement Inc.
• Advanced Manufacturing Institute

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Questions?