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Vibrating wire strain gauges are available for embedment and surface mount applications. Since they output frequency, they are particulary suitable for Civil engineering applications and are easily data logged and data can be transmitted up to 1 km from the instrument.
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| VW Arc weld surface Strain Gauge | ||||||||||
click here for Vibrating Wire Strain Gauge PDF
Sister bars are used to monitor strains in concrete and typically are used in concrete piles as an option to embedment strain gauges, where they are more robust than strain gauges. The sister bar, available in various diameters, consists of a calibrated hollow reference tube containing a single vibrating wire strain gauge. The reference tube is welded to extension rebars to provide for anchorage. The Sister bars are installed adjacent to main vertical rebar. A variant of the sister bar, the brother bar, is used to connect main vertical pile rebars together so that loads act through the calibrated strain gauge section.
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| VW 16 mm dia Sister Bar | ||||||||||
Vibrating Wire Displacement Transducer.
The displacement transducers are available in various operating ranges and the square of the frequency signal
is directly proportional to the amount of displacement. These units are used in crackmeters and rod extensometers.
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| VW Displacement Transducer | ||||||||||
click here for Vibrating Wire Displacement Transducers PDF
Vibrating Wire settlement system
The system uses a vibrating wire transducer buried within fill. The transducer is connected to a pair of fluid filled small
bore tues which lead to a datum header tank located outside of the construction area. Settlement or heave of the buried transducer
cause a change in applied fluid head on the transducer from the fixed datum allowing settlement to be determined.
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| VW Settlement System | ||||||||||
click here for Vibrating Wire Settlement System PDF
Soil extensometers are used to measure large deformations typically in embankments, and generally are installed in a chain so that the strain profile of a longitudinal section in embankment or dams can be determined.
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| VW Soil Extensometers | ||||||||||
click here for Vibrating Wire Soil Extensometer PDF
The triaxial crackmeter uses 3 vibrating wire displacement transducers to measure crack displacement in X, Y, and Z axes.Typical applications include the measuring in the dimensional change of mass concrete joints on dam faces or in galleries of dams. The units are submersible to 350 m water head.
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| VW Triaxial Crackmeter | ||||||||||
click here for Vibrating Wire Crackmeters PDF
The extensometer is a similar size to that of a conventional rock anchor used for slope stability and anchoring in tunnels and excavations. The extensometer contains 4 internal rods such that the relative extensions of the unit can be determined. The unit is tensioned in the same way as working rockbolts and is acted on by the same forces as the working rockbolts. The relative movement of the inner rods is normally monitored using a depth gauge, although this can be automated using potentiometric displacement transducers.
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| Load anchor Extensometer | ||||||||||
Rod extensometers are installed generally within boreholes to measure settlement or heave. Extensometer can have multiple anchors fixed within the borehole, each connected via rods to the reference head. Relative movement of the anchors to the reference head is determined by manual measurement at the head using a digital depth gauge.
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| Mechanical Rod Extensometer head | ||||||||||
Vibrating Wire Rod Extensometer.
The vibrating wire rod extensometer is similar to the mechanical rod extensometer, but instead of monitoring movement manually,
it is fitted with Vibrating wire displacement transducers allowing readings to be obtained remotely and for data logging.
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| VW Rod Extensometer head | ||||||||||
click here for Vibrating Wire Rod Extensometer PDF
A magnetic extensometer consists of an thick wall tube (or inclinometer tube) onto which annular magnetic targets are installed at various depths within a borehole. Normally, one datum magnet is installed at the distal end of the tube in strata which is considered to be stable and outside of any influence of construction induced settlement. A reed switch probe is used to determine the postion of the magnet targets within the borehole and is referenced to the datum magnet, thus determining the settlement profile within the borehole.
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| Inclinometer Spider magnet | ||||||||||
click here for Magnetic Extensometer PDF
This crackmeter allows for the determination of the movement of a crack in X,Y, and Z axes. Readings are obtained manually using a digital depth gauge.
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| Mechanical Triaxial Crackmeter | ||||||||||
click here for Mechanical Crackmeter PDF
Tape Extensometer.
The
tape extensometer is used to measure changes in distance between two fixed points. Typically this is used to measure the profile
of tunnels where multiple reference points are installed on a cross section. Successive readings enable a profile of
tunnel deformation with time to be determined.
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| Tape Extensometer | ||||||||||
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