Non-Contact Measurements Pre-Stressed Concrete Beams

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26 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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A New

Real
-
Time, Non
-
Contact

Transfer
-
Length Measurement Technique

Dr. Terry Beck (Mechanical Engineering)

Dr. Robert Peterman (Civil Engineering)

Dr. John Wu (Industrial Engineering)

Weixin Zhao (Industrial Engineering)

Inventors:

What is the problem for which
you have a solution

?

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

How is the
problem

being solved now?



What’s wrong with current solutions?


We simply don’t measure it?

Why Don’t 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

Current Tool

Whittemore Gauge

48
MPa
(7 KSI) SLW Specimen with 1/2"-Special FWC Strand
-1800
-1600
-1400
-1200
-1000
-800
-600
-400
-200
0
0
20
40
60
80
100
Distance Along Beam (cm)
Microstrain
At Transfer of
Prestress
3 Days After Transfer
14 Days After Transfer
36 Days After Transfer
66 Days After Transfer
0
0
500
1000
1500
2000
2500
Distance Along Beam (mm)
48
MPa
(7 KSI) SLW Specimen with 1/2"-Special FWC Strand
-1800
-1600
-1400
-1200
-1000
-800
-600
-400
-200
0
0
20
40
60
80
100
Distance Along Beam (cm)
Microstrain
At Transfer of
Prestress
3 Days After Transfer
14 Days After Transfer
36 Days After Transfer
66 Days After Transfer
0
0
500
1000
1500
2000
2500
Distance Along Beam (mm)
Strain in Pretensioned Concrete Member

What is our solution?



Non
-
Contact Measurements


Portable as Current Tool


Much Higher Precision


More Flexible

Concept of Laser Speckle

Photograph of Laser Speckle on Concrete


Peak Distances vs. Strains Measures

0.02mm deflection

0.10mm deflection

0.20mm deflection

Actual experimental work

we have performed?


Concrete beam cutting experiment

Prototype Design

Experiment Setup

Beam Cutting

Cutting Pretensioned Specimen

Comparison of Different Strain Gauges

Right Side
-50.0
0.0
50.0
100.0
150.0
200.0
0
20
40
60
80
100
Distance along beam(cm)
Microstrain
Whittemore 11-16
Optical 11-16
Prototype Specification

4

ㄯ㐠in捨敳

㠠in

Resolution: < 10
me


1m
m

Weight: 3 lbs

Dimension: 11”x6”x4”

Measurement speed: 15 samples/second

Optical Sensor

Concrete Cylinder Compression Experiment

Electronic
Strain
Gage

Optical
Strain
Gage


Concrete Cylinder Results

0
50
100
150
200
250
300
350
400
450
500
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Load (lbs)
Microstrain
ESG at surface 1
Optical at surface 1
Concrete Cylinder Results

Differences Between Optical and ESG
-4
-3
-2
-1
0
1
2
3
4
5
6
7
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Load (lbs)
Microstrain
What is the closest prior art that might be
cited against the novelty of your invention?


None !

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


Additional K
-
State Personnel

Have Been Added


Commercialization Manager.


2 MBA Students (Final Project).


Product Design Engineer.


2 Other Design Engineers (Optics and
Electrical).


Precision Optical Measurements, Inc.

The Goal


Version 1 available for use this summer.


For sale within one year (Approx. $20k)

The Future

Measurement Surface

Traverse

Sensor

Auto Measuring System

Delta Strain Rosette

Who specifically would be

a possible commercial partner or

licensee for your invention?



Precision Optical Measurement Inc.


Advanced Manufacturing Institute

Questions?