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Geokon 4200ER, Instruction Manual

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Geokon 4200ER Instruction Manual Download Page 10

4 

Alternative Method: 
 

Tie two short pieces of steel rebar to the existing rebar using  nylon Tie-wraps, as shown in 
Figure 3B. Then tie the strain gage to the short pieces of rebar again using nylon tie wraps. 
This method avoids the resonance problems associated with the previous method.

 

 

 

 
 
 
 
 
 

 

Figure 3B - Alternative Method for attaching VCE 4200X straingages to rebar. 

 

Summary of Contents for 4200ER

Page 1: ...by any means without the written consent of Geokon Inc The information contained herein is believed to be accurate and reliable However Geokon Inc assumes no responsibility for errors omissions or misinterpretation The information herein is subject to change without notification Copyright 2016 by Geokon Inc Doc Rev A 04 07 2017 ...

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Page 3: ...re are no warranties except as stated herein There are no other warranties expressed or implied including but not limited to the implied warranties of merchantability and of fitness for a particular purpose Geokon Inc 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 t...

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Page 5: ...e GK 404 Readout Box 7 3 3 Operation of the GK 405 Readout Box 8 3 4 MICRO 6000 Datalogger 9 3 5 Measuring Temperatures 9 4 DATA REDUCTION FOR THE GK 403 GK 404 or GK 405 in POSITION D 10 4 1 Conversion of Readings to Strain Changes 10 4 2 Temperature Corrections 11 4 3 Shrinkage Effects 12 4 4 Creep Effects 12 4 5 Effect of Autogenous Growth 12 5 TROUBLESHOOTING 13 APPENDIX A SPECIFICATIONS 14 A ...

Page 6: ...r 4 Figure 4 Lightning Protection Scheme 6 Table 1 Embedment Strain Gage Readout Positions 7 Figure 5 GK405 Readout Unit 8 Table 2 Embedment Strain Gage Datalogger Parameters 9 Equation 1 Strain Calculation channel D 10 Table A 1 Strain Gage Specifications 14 Equation C 1 Convert Thermistor Resistance to Temperature 15 Table C 1 Thermistor Resistance versus Temperature 15 Table B 2 High Temperatur...

Page 7: ... mass concrete Deformations in the concrete will cause the two end blocks to move relative to one another altering the tension in the steel wire This change in tension is measured as a change in the resonant frequency of vibration of the wire Electromagnetic coils that are located close to the wire accomplish excitation and readout of the gage frequency Portable readouts or dataloggers available f...

Page 8: ...e existing ambient temperature See Appendix B for the resistance to temperature conversion and resistance v temperature table Return any faulty gages to the factory Gages should not be opened in the field 2 1 Adjusting the Desired Range Gages are supplied with the wire tension set in approximate rmid range If the range needs to be at some other position this is accomplished by the following proced...

Page 9: ...ain Gages to Rebar Note the following instructions to suspend the model VCE 4200X strain gage between rebar 1 Wrap a layer of self vulcanizing rubber tape around the gage in the two places shown in Figure 3 around the tie points The rubber layer serves as a shock absorber dampening any vibrations of the suspension system Sometimes without the rubber layers as the tie wires are tightened the resona...

Page 10: ...r using nylon Tie wraps as shown in Figure 3B Then tie the strain gage to the short pieces of rebar again using nylon tie wraps This method avoids the resonance problems associated with the previous method Figure 3B Alternative Method for attaching VCE 4200X straingages to rebar ...

Page 11: ...he panel can have built in jacks or a single connection with a rotary position selector switch Cables may be spliced to lengthen them without affecting the gage readings Always maintain polarity by connecting color to color Always waterproof the splice completely preferably using a splice kit epoxy based such as the 3M Scotchcast kit model 82 A1 Cables may be terminated by stripping and tinning an...

Page 12: ... removable top so in the event the protection board LAB 3 is damaged the user may service the components or replace the board A connection is made between this enclosure and earth ground to facilitate the passing of transients away from the gage See Figure 4 Consult the factory for additional information on these or alternate lightning protection schemes Plasma surge arrestors can be epoxy potted ...

Page 13: ...t may change one or two digits while reading Press the Store button to record the value displayed If the no reading displays or the reading is unstable see section 5 for troubleshooting suggestions The thermistor will be read and displayed on the screen above the gage reading in degrees centigrade 3 The unit will automatically turn itself off after approximately 2 minutes to conserve power 3 2 Ope...

Page 14: ...peration of the GK 405 Readout Box The GK 405 Vibrating Wire Readout is made up of two components the Readout Unit consisting of a Windows Mobile handheld PC running the GK 405 Vibrating Wire Readout Application the GK 405 Remote Module which is housed in a weather proof enclosure and connects to the vibrating wire sensor by means of 1 Flying leads with alligator type clips when the sensor cable t...

Page 15: ... start and end frequencies of the calibration To maximize the stability and resolution of the sensor a relatively narrow band of excitation frequency should be selected One could calculate these settings by taking an initial reading and then setting the starting frequency to 200 Hz below and the ending frequency 200 Hz above Model 4200ER MICRO 6000 Gage Type 4200 Gage Factor G Shown on cal sheet S...

Page 16: ...ts R must be multiplied by the gage factor G on the calibration sheet to obtain true values of microstrain G R1 R0 Equation 1 Strain Calculation channel D Where R0 and R1 are the readout box readings in Pos D Note when R1 R0 is positive the strain is tensile A typical calibration sheet is shown in Figure 6 It will be noted that the 4200Er output is not very linear varying as much a 3 FS Therefor i...

Page 17: ...s attached If the concrete expanded by exactly the same amount as the wire then the wire tension would remain constant and no correction would be necessary The effect of temperature on the 4200ER strain gage is complex it varies depending on the strain level A Typical temperature correction factor to be applied to the 4200ER 10 000 is as follows Temperature Correction Factor 0 000401 R1 1 067 T1 T...

Page 18: ...n gage inside a concrete block that remains unloaded but exposed to the same moisture conditions as the active gages Strains measured on this gage may be used as a correction 4 4 Creep Effects It is also well known that concrete will creep under a sustained load What may seem to be a gradually increasing load as evidenced by a gradually increasing strain may in fact be strain due to creeping under...

Page 19: ...pment away from the installation or install electronic filtering Make sure the shield drain wire is connected to ground whether using a portable readout or datalogger Does the readout work with another gage If not the readout may have a low battery or be malfunctioning Symptom Strain Gage Fails to Read Is the cable cut or crushed This can be checked with an ohmmeter Nominal resistance between the ...

Page 20: ...ength Diameter 6 00 x 0 750 153 19 mm Dimensions coil 0 875 0 875 22 22 mm Coil Resistance 50 Temperature Range 20 to 80 C Table A 1 Strain Gage Specifications Notes Depends on the readout figures in Table A 1 pertain to the GK 403 or GK 404 Readout System Accuracy takes into account hysteresis non linearity misalignment batch factor variations and other aspects of the actual measurement program A...

Page 21: ...3 342 2 83 107 9 123 77 66K 36 8006 4 1363 44 331 5 84 105 2 124 72 81K 35 7618 5 1310 45 321 2 85 102 5 125 68 30K 34 7252 6 1260 46 311 3 86 99 9 126 64 09K 33 6905 7 1212 47 301 7 87 97 3 127 60 17K 32 6576 8 1167 48 292 4 88 94 9 128 56 51K 31 6265 9 1123 49 283 5 89 92 5 129 53 10K 30 5971 10 1081 50 274 9 90 90 2 130 49 91K 29 5692 11 1040 51 266 6 91 87 9 131 46 94K 28 5427 12 1002 52 258 6...

Page 22: ...203 35 6 235 18 090 12 4 543 44 1 432 76 539 9 108 235 3 140 114 5 172 61 0 204 35 1 236 17 255 13 4 368 45 1 385 77 525 0 109 229 7 141 112 1 173 59 9 205 34 5 237 16 463 14 4 201 46 1 340 78 510 6 110 224 3 142 109 8 174 58 8 206 33 9 238 15 712 15 4 041 47 1 297 79 496 7 111 219 0 143 107 5 175 57 7 207 33 4 239 14 999 16 3 888 48 1 255 80 483 2 112 213 9 144 105 3 176 56 7 208 32 9 240 14 323 ...

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