The gauge consists of two end blocks with a tensioned steel wire between them.
Around the wire is a magnetic coil which when pulsed by a vibrating readout or data logger interface plucks the wire and measures the resultant resonant frequency of vibration.
Geosense® VWS-2100 series vibrating wire embedment strain gauges are designed for direct embedment in concrete.
The strain gauge operates on the principle that a tensioned wire, when plucked, vibrates at its resonant frequency. The square of this frequency is proportional to the strain in the wire.
Deformation within the concrete will cause the two end blocks will move relative to each other. The tension in the wire between the blocks will change accordingly thus altering the resonant frequency of the wire.