VW Embedment Strain Gauge

 

Applications

Durham Geo's VW embedment strain gauge is used to measure strain in reinforced concrete and mass concrete.
 

Operation

The embedment strain gauge operates on the principle that a tensioned wire, when plucked, vibrates at a frequency that is proportional to the strain in the wire. The gauge is constructed so that a wire is held in tension between two end flanges. Loading of the concrete structure changes the distance between the two flanges and results in a change in the tension of the wire. An electromagnet is used to pluck the wire and measure the frequency of vibration. Strain is then calculated by applying calibration factors to the frequency measurement.
 

Installation

In reinforced or pre-stressed concrete applications, the embedment strain gauge is usually tied to the reinforcing cage. In mass concrete applications, the gauge may be installed either before or immediately after placement of the concrete. Gauges may be configured in a rosette either by direct placement in the soft concrete or by attachment to a rosette adapter.

Embedment Strain Gauge

Advantages

Permanently Attached Coils: The coils used to excite and read the vibrating wire cannot be accidentally separated from the body during installation and wiring operations.

Built-in Temperature Sensor: The temperature sensor is useful for temperature corrections when the gauge is installed on materials that have a different temperature coefficient.

Reliable Signal Transmission: The arc-weldable strain gauge provides a strong signal that can be transmitted reliably over long distances with properly shielded cable.

For more information

Please download the datasheet and manual for the VW Embedment Strain Gauge. These documents can be viewed and printed with Adobe Acrobat Reader.

Embedment Strain Gauge Diagram

VW Embedment Strain Gauge Specifications

EMBEDMENT STRAIN GAUGE
VW Embedment Strain Gauge52650226Vibrating wire strain gauge for monitoring strain in reinforced or mass concrete. Includes a built-in thermistor. Signal cable not included
Range3,000 microstrain, set mid-range
Resolution1 microstrain with VW Indicator
Accuracy± 0.5% FS
Thermal Coefficient12 ppm /°C
Length168 mm ( 6.625" )
PICKUP AND SIGNAL CABLE
VW Standard Clip-On Pickup52641110Standard clip-on pickup includes 10 feet (3m) of signal cable and a hose clamp
VW Custom Length Clip-On Pickup52641100Custom clip-on pickup includes the pickup and a hose clamp. Signal cable must be ordered separately and will be installed at the factory
Signal Cable50613824Shielded cable with four 22-gauge tinned-copper conductors and flexible poly-vinyl chloride (PVC) jacket rated to 80°C(176°F)
TERMINAL BOXES
Terminal Box for 6 sensors57711606Provides terminals for signal cable from 6, 12, or 24 sensors. Sensors are selected by rotary switch. Dimensions of 6-sensor box are 240 x 190 x 120 mm (9.5 x 7.5 x 4.75"). Dimensions of 12 and 24-sensor boxes are 290 x 345 x 135 mm (11.5 x 13.5 x 5.25")
Terminal Box for 12 Sensors57711600
Terminal Box for 24 Sensors97711624
Universal Connector57705001For terminating a single cable. Connector not required when sensors are connected to a terminal box, a data logger, or to the terminal posts on the VW Data Recorder
READOUT
VW Data Recorder52613500The VW Data Recorder displays VW sensor readings in Hz or H2 /1000 and thermistor data in degrees C. It can also record the readings. See separate datasheet.
Jumper Cable for Terminal Box.52613557The jumper cable is required when the VW Data Recorder is to be connected to a terminal box or to a connector attached to signal cable
DATA LOGGERS
VW MiniLogger52613310The VW MiniLogger is a compact, low-cost data logger for one sensor. See separate datasheet
4-Channel V-Logger52615140
8-Channel V-Logger52615180
Campbell Scientific Data LoggersCampbell data loggers with a VW interface and the AM16/32 multiplexer can accommodate 16 sensors with temperature readings or 32 sensors without without temperature readings