Vibrating wire strain gauges provide measurements of strain in steel or concrete. The measurements are used to calculate structural loads or stresses. Arc-weldable strain gauges are fixed to steel structures via weldable end-blocks orto concrete surface with special mounting blocks. Embedment strain gauges are cast into concrete structures.
? Piles and mass concrete
? Concrete structures, beams and columns
? Concrete foundations and diaphragm walls
? Tunnel segments
? Steel structures, pipes and arch supports
? Gravity and arch dams
? RCC dams
? Bridges and viaducts
? Reliable long term performance
? Robust design, suitable for demanding environments
? Aged thermally to minimize long-term drift
? Immunity to voltage surges
? Built-in temperature sensor
? Totally waterproof
? Accurate readings even with long cable lengths
A tensioned wire, when plucked, vibrates at its resonant frequency. The square of this frequency is proportional to the strain in the wire. To make use of this principle, the vibrating wire strain gauge is designed to hold a wire in tension between two end blocks that are fixed to the structure. A electromagnetic coil assembly is used to pluck the wire and then to return a frequency signal to the readout units.
Deformation of the structure changes the distance between the two end blocks, altering the tension of the wire and its resonant frequency. The returned signal is converted to units of microstrain. Frequency signals are similar to digital signals and therefore insensitive to resistance changes in connecting cables caused by contact resistance or leakage to ground. Gauges may be read up to 1000 meters away from their location. The strain gauge has a built-in thermistor to provide temperature data for thermal corrections, if necessary.