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Strain Gauges for Steel and Concrete

Vibrating-Wire Strain Gauges are used to monitor strain in steel and concrete. Datasheet

Struts instrumented with arc-weldable strain gauges

Struts instrumented with arc-weldable strain gauges

Weldable Strain Gauges

Careful positioning and protective foil wraps yielded a 100% survival rate during shotcreting.

Surface-mount strain gauge

Special end-blocks allow surface installation of strain gauges on concrete

Weldable Strain Gauges

Weldable strain gauges are installed on steel. Applications include:

  • Monitoring changes in load on structural elements during and after construction.
  • Monitoring the performance of wall anchors and other post-tensioned support systems.
  • Measuring strain in tunnel linings
  • Monitoring distribution of load in pile tests.

Embedment Strain Gauges

Embedment strain gauges monitor strain in concrete. Typical applications include:

  • Measuring strains in mass concrete.
  • Measuring curing strains.

Operation

The vibrating wire 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 monitored element changes the distance between the two flanges and results in a change in the tension of the wire and its output signal.

An electromagnet is used to excite the wire and measure the resulting frequency of vibration. Strain is then calculated by squaring the frequency value and applying calibration constant.

 

Arc-Weldable Strain Gauge

Arc-Weldable Gauges

Arc-weldable strain gauges are suitable for most applications and are quickly installed using an arc welder. They can be adapted for concrete by using groutable mounting blocks.

Sensor Type: Vibrating Wire.
Gauge Length: 6 inches ( 150 mm).
Range: 3,000 μm.
Resolution: 1.0 μm.
Accuracy: ±0.5% FS.
Non-Linearity: better than 0.5% FS.
Temp Range: −20°C to +80°C.

spotweld-strain-gauge-350

Spot-Weldable Gauges

Spot-weldable strain gauges are used when space is limited or when low-heat, shallow welds are required. For short-term applications, they can be installed with epoxy adhesive.

Sensor Type: Vibrating Wire Gauge
Length: 2 inches
Range: 3,000 μm
Resolution: 0.4 μm
Accuracy: ±0.5% FS
Non-Linearity: better than 0.5% FS
Temp Range: −20°C to +80°C

Embedment Strain Gauge

Embedment Gauges

Embedment strain gauges are designed for direct embedment in concrete. The gauge is typically tied to the reinforcing cage. In mass concrete applications, the gauge is installed either before or immediately after placement of the concrete.

Sensor Type: Vibrating Wire
Gauge Length: 6 inch ( 153 mm)
Range: 3,000 μm
Resolution: 1.0 μm
Accuracy: ±0.5% FS
Non-Linearity: better than 0.5% FS
Temp Range: −20°C to +80°C