Geokon 4200 Series User manual

©2018, GEOKON. All rights reserved.
Document Revision: BB | Release date: 12/4/18
Model 4200 Series
Vibrating Wire Strain Gauges
Instruction Manual

WARRANTY STATEMENT
GEOKON warrants its products to be free of defects in materials and workmanship,
under normal use and service for a period of 13 months from date of purchase. If the
unit should malfunction, it must be returned to the factory for evaluation, freight
prepaid. Upon examination by GEOKON, if the unit is found to be defective, it will be
repaired or replaced at no charge. However, the WARRANTY IS VOID if the unit shows
evidence of having been tampered with or shows evidence of being damaged as a
result of excessive corrosion or current, heat, moisture or vibration, improper specifi-
cation, misapplication, misuse or other operating conditions outside of GEOKON’s
control. Components that wear or are damaged by misuse are not warranted. This
includes fuses and batteries.
GEOKON manufactures scientific instruments whose misuse is potentially dangerous.
The instruments are intended to be installed and used only by qualified personnel.
There are no warranties except as stated herein. There are no other warranties,
expressed or implied, including but not limited to the implied warranties of merchant-
ability and of fitness for a particular purpose. GEOKON is not responsible for any
damages or losses caused to other equipment, whether direct, indirect, incidental,
special or consequential which the purchaser may experience as a result of the instal-
lation or use of the product. The buyer’s sole remedy for any breach of this agreement
by GEOKON or any breach of any warranty by GEOKON shall not exceed the purchase
price paid by the purchaser to GEOKON for the unit or units, or equipment directly
affected by such breach. Under no circumstances will GEOKON reimburse the
claimant for loss incurred in removing and/or reinstalling equipment.
Every precaution for accuracy has been taken in the preparation of manuals and/or
software, however, GEOKON neither assumes responsibility for any omissions or
errors that may appear nor assumes liability for any damages or losses that result
from the use of the products in accordance with the information contained in the
manual or software.
No part of this instruction manual may be reproduced, by any means, without the written consent of GEOKON. The
information contained herein is believed to be accurate and reliable. However, GEOKON assumes no responsibility
for errors, omissions or misinterpretation. The information herein is subject to change without notification.
The GEOKON® wordmark and logo are registered trademarks with the United States Patent and Trademark Office.

I
TABLE OF CONTENTS
1. INTRODUCTION............................................................................................................................................1
2. MODELS ................................................................................................................................................................2
2.1 MODELS 4200 AND 4200L ........................................................................................................2
2.2 MODELS 4200-6 AND 4200-7 .................................................................................................3
2.3 MODEL 4202............................................................................................................................................3
2.4 MODEL 4210............................................................................................................................................4
3. PRIOR TO INSTALLATION...............................................................................................................5
3.1 ADJUSTING GAUGE TO THE DESIRED RANGE .......................................................5
3.2 GAUGE AND CABLE ASSEMBLY ...........................................................................................5
3.3 PRELIMINARY CHECK ....................................................................................................................5
4. INSTALLING THE GAUGES IN CONCRETE..................................................................7
4.1 DIRECT ATTACHMENT TO REBAR.......................................................................................7
4.2 SUSPENSION METHOD .................................................................................................................7
4.3 ALTERNATIVE SUSPENSION METHOD...........................................................................8
4.4 USING PRE-CAST BRIQUETTES, SHOTCRETE, OR GROUTING.................9
4.5 CABLE SPLICING AND TERMINATION............................................................................9
4.6 LIGHTNING PROTECTION............................................................................................................9
5. TAKING READINGS ............................................................................................................................. 11
5.1 MICRO-6000 DATALOGGER .................................................................................................. 11
5.2 EMBEDMENT STRAIN GAUGE READOUT POSITIONS.................................. 11
5.3 GK-404 READOUT BOX.............................................................................................................. 11
5.3.1 OPERATING THE GK-404 ........................................................................................................... 12
5.4 GK-405 READOUT BOX.............................................................................................................. 12
5.4.1 CONNECTING SENSORS WITH 10-PIN BULKHEAD CONNECTORS
ATTACHED ....................................................................................................................................... 13
5.4.2 CONNECTING SENSORS WITH BARE LEADS................................................................... 13
5.4.3 OPERATING THE GK-405 ........................................................................................................... 13
5.5 GK-403 READOUT BOX (OBSOLETE MODEL) ........................................................ 14
5.5.1 CONNECTING SENSORS WITH 10-PIN BULKHEAD CONNECTORS
ATTACHED ....................................................................................................................................... 14
5.5.2 CONNECTING SENSORS WITH BARE LEADS................................................................... 14
5.5.3 OPERATING THE GK-403 ........................................................................................................... 14
5.6 MEASURING TEMPERATURES ........................................................................................... 14
6. DATA REDUCTION ................................................................................................................................15

II
6.1 READOUT BOX POSITION A .................................................................................................. 15
6.2 READOUT BOX POSITION B................................................................................................... 15
6.3 READOUT BOX POSITIONS D & E.................................................................................... 15
6.4 STRAIN RESOLUTION.................................................................................................................. 16
6.5 TEMPERATURE CORRECTIONS .......................................................................................... 16
6.5.1 MODEL 4200-6 / 4200-7 CORRECTIONS.............................................................................. 17
6.6 SHRINKAGE EFFECTS.................................................................................................................. 17
6.7 CREEP EFFECTS ................................................................................................................................17
6.8 EFFECT OF AUTOGENOUS GROWTH............................................................................. 18
6.9 CONVERTING STRAIN TO LOAD........................................................................................ 18
6.10 EFFECTIVE MODULUS.............................................................................................................. 18
7. TROUBLESHOOTING........................................................................................................................... 19
APPENDIX A. SPECIFICATIONS................................................................................................... 21
A.1 STRAIN GAUGE ................................................................................................................................. 21
A.2 THERMISTOR ...................................................................................................................................... 21
APPENDIX B. THEORY OF OPERATION .............................................................................. 22
APPENDIX C. THERMISTOR TEMPERATURE DERIVATION ....................... 24
APPENDIX D. HIGH-TEMPERATURE THERMISTOR
LINEARIZATION ...................................................................................................... 25
APPENDIX E. NO STRESS STRAIN ENCLOSURE.................................................... 26
APPENDIX F. MODEL 4200HT-T HIGH-TEMPERATURE STRAIN
GAUGE ................................................................................................................................28
APPENDIX G. MEASUREMENT AND CORRECTION OF
TEMPERATURE EFFECTS............................................................................. 29

III
FIGURES
FIGURE 1: ON-SITE INSTALLATION PHOTO ....................................................................1
FIGURE 2: MODEL 4200 VIBRATING WIRE STRAIN GAUGE .........................................2
FIGURE 3: MODEL 4200L VIBRATING WIRE STRAIN GAUGE .......................................2
FIGURE 4: MODEL 4200-6 VIBRATING WIRE STRAIN GAUGE ......................................3
FIGURE 5: MODEL 4200-7 VIBRATING WIRE STRAIN GAUGE ......................................3
FIGURE 6: MODEL 4202 VIBRATING WIRE STRAIN GAUGE .........................................3
FIGURE 7: MODEL 4210 VIBRATING WIRE STRAIN GAUGE .........................................4
FIGURE 8: ADJUSTING THE RANGE OF THE STRAIN GAUGE .......................................5
FIGURE 9: ASSEMBLED STRAIN GAUGE AND COIL HOUSING ....................................5
FIGURE 10: ATTACHING GAUGES TO REBAR .................................................................7
FIGURE 11: SUSPENDING STRAIN GAUGES BETWEEN REBAR ...................................8
FIGURE 12: ALTERNATIVE METHOD FOR ATTACHING GAUGES TO REBAR ...............8
FIGURE 13: LIGHTNING PROTECTION SCHEME ..........................................................10
FIGURE 14: GK-404 READOUT .......................................................................................12
FIGURE 15: LEMO CONNECTOR TO GK-404 .................................................................12
FIGURE 16: GK-405 READOUT .......................................................................................13
FIGURE 17: NO STRESS STRAIN ENCLOSURE .............................................................26
FIGURE 18: MODEL 4200HT-T .......................................................................................28

IV
TABLES
TABLE 1: HEAT SHRINK COLOR DESIGNATIONS...........................................................2
TABLE 2: EMBEDMENT STRAIN GAUGE DATALOGGER PARAMETERS....................11
TABLE 3: READOUT POSITIONS......................................................................................11
TABLE 4: EMBEDMENT STRAIN GAUGE FACTORS......................................................15
TABLE 5: STRAIN RESOLUTION ......................................................................................16
TABLE 6: EFFECTIVE MODULUS .....................................................................................18
TABLE 7: RESISTANCE WORK SHEET............................................................................20
TABLE 8: SAMPLE RESISTANCE .....................................................................................20
TABLE 9: STRAIN GAUGE SPECIFICATIONS..................................................................21
TABLE 10: EMBEDMENT STRAIN GAUGE THEORETICAL PARAMETERS .................22
TABLE 11: THERMISTOR RESISTANCE VERSUS TEMPERATURE ..............................24
TABLE 12: THERMISTOR RESISTANCE VERSUS TEMPERATURE FOR MODEL
4200HT ..........................................................................................................25

V
EQUATIONS
EQUATION 1: PERIOD TO DIGITS CONVERSION........................................................... 15
EQUATION 2: THEORETICAL STRAIN ............................................................................. 15
EQUATION 3: APPARENT STRAIN................................................................................... 15
EQUATION 4: CORRECTION FOR TEMPERATURE EFFECTS ON THE GAUGE............ 16
EQUATION 5: TRUE, LOAD-RELATED STRAIN CORRECTED FOR TEMPERATURE .... 16
EQUATION 6: ACTUAL STRAIN........................................................................................ 17
EQUATION 7: STRAIN TO LOAD FORMULA ................................................................... 18
EQUATION 8: RESISTANCE TO TEMPERATURE ............................................................ 24
EQUATION 9: HIGH-TEMPERATURE RESISTANCE TO TEMPERATURE...................... 25
EQUATION 10: TEMPERATURE-INDUCED STRESS ...................................................... 29
EQUATION 11: COMBINED TEMPERATURE AND LOAD-RELATED STRESS.............. 29
EQUATION 12: EXTERNAL LOAD STRESS...................................................................... 29
EQUATION 13: ACTUAL STRAIN ..................................................................................... 29

VI