Strain Gages • Strainmeters
 
Photo of Model 3900  

Model 3900 Embedment Strain Gage
The Model 3900 Embedment Strain Gage is designed for the measurement of dynamic strains in concrete structures, asphalt roadways and soils. It comprises a full bridge strain gaged proving ring coupled, between two flanges, with a spring and shaft. When the flanges move relative to one another, the tension in the spring changes and hence the strain in the proving ring. A PVC tube serves as a protective housing and holds the gage at the desired initial tension.

Specifications  
Standard Range 5000 microstrain
Sensitivity 0.125 mV/V nominal
Accuracy ±0.025% F.S.
Nonlinearity < 0.5% F.S.
Temperature Range –20°C to +80°C
Active Gage Length* 203 mm
*Other lengths available on request

Photo of Model 4000  

Model 4000 Arc Weldable Strain Gage
The Model 4000 Strain Gage is designed primarily for arc welding to steel structures such as tunnel linings, excavation bracing, piles and bridges. The gage has a 150 mm gage length (longer or shorter versions are also available) a 3000 microstrain range and a 1 microstrain sensitivity. The gage can be adapted for bonding to concrete or for bolting to steel surfaces by modification of the end blocks.

Specifications  
Standard Range 3000 microstrain
Sensitivity 1.0 microstrain
Accuracy ±0.1% F.S.
Nonlinearity < 0.5% F.S.
Temperature Range –20°C to +80°C
Active Gage Length* 150 mm (5.875in.)
*Other lengths available on request

Photo of Model 4100 and 4150  

Model 4100 • 4150 Spot Weldable Strain Gages
The Model 4100/4150 Strain Gage has a 51 mm gage length (3000 microstrain range, 1 microstrain sensitivity) and is designed to measure strains in steel structures (4100) and on reinforcement bars (4150) where space may be limited. The gage is installed quickly and easily by means of a capacitive discharge spot welder or, for short-term use, with special epoxy adhesives; the latter method of attachment permits the use of this gage on concrete.

Specifications  
Standard Range 3000 microstrain
Sensitivity 0.5 to 1.0 microstrain
Accuracy ±0.1% F.S.
Nonlinearity < 0.5% F.S.
Temperature Range –20°C to +80°C
Active Gage Length 51 mm

Photo of Model 4200, 4210 and 4202  

Model 4200/4210/4202 Concrete Embedment Strain Gages
These Strain Gages are designed for direct embedment in concrete. The 4200 (standard model) has a 153 mm gage length and 1 microstrain sensitivity and is commonly used for strain measurements in foundations, piles, bridges, dams, tunnel linings, etc. The 4210 has the same range as the Model 4200 but has a 250 mm gage length making it particularly suitable for use in large aggregate concrete. The 4202, with a 51 mm gage length, is designed for laboratory use and / or where there are space limitations. Low modulus versions, for measuring concrete curing strains, are also available (contact Geokon for details).

Specifications 4200 4210 4202
Standard Range 3000 microstrain (for each model)
Sensitivity (microstrain) 0.5 to 1.0 0.4 0.4
Accuracy ±0.1% F.S. ±0.1% F.S. ±0.1% F.S.
Nonlinearity < 0.5% F.S. < 0.5% F.S. < 0.5% F.S.
Temperature Range¹ –20°C to +80°C (for each model)
Active Gage Length 153 mm 250 mm² 51 mm
¹Model 4200 high temperature version (up to 200°C) available on request
²Other lengths available on request

Photo of Model 4200HT  

Model 4200HT High Temp. Embedment Strain Gage
The Model 4200HT High Temperature Embedment Strain Gage is similar to the standard Model 4200 but is constructed using components that can be used at temperatures up to 200°C. It is particularly useful for measurements in autoclaved spun concrete piles.

Specifications  
Standard Range 3000 microstrain
Sensitivity 1.0 microstrain
Accuracy ±0.1% F.S.
Nonlinearity < 0.5% F.S.
Temperature Range –20°C to +200°C
Active Gage Length* 153 mm

Photo of Model 4911, 4911A  

Model 4911 • 4911A Rebar Strainmeters
The Model 4911 Rebar Strainmeter is designed for measuring strains in foundations, slurry walls, precast piles, caissons, bridge abutments, tunnel liners, etc. The standard Model 4911 (#4 rebar), known as the “Sister Bar," is installed alongside structural rebar. Larger models (4911A) are available for welding directly into structural rebar. Where short-term dynamic measurements are to be made, bonded resistance strain gages can be substituted, or added (Model 3911/3911A).

Specifications  
Standard Range 2500 microstrain
Sensitivity 0.4 microstrain
Accuracy ±0.25% F.S.
Nonlinearity < 0.5% F.S.
Temperature Range –20°C to +80°C
Sizes

(4911) #4 Rebar (Sister Bar)
(4911A) 6, 7, 8, 9, 10, 11 and 12

Length (4911) 1384 mm
(4911A) 1105 mm