Vibrating Wire Gauges

Vibrating wire gauges measure strain in structural elements by detecting changes in the resonant frequency of a tensioned wire contained within the sensor. As the structure strains, the wire tension changes, altering its natural frequency. This frequency change is measured precisely and converted to strain. The technique is inherently stable over very long periods, unlike electrical resistance strain gauges, which suffer from drift, making vibrating wire technology the standard for long-term structural monitoring.

TRSC installs vibrating wire gauges in concrete elements (embedded during construction or in drilled boreholes in existing structures), on steel members (surface-mounted), and in foundation systems (embedded in grout or attached to piles). The sensors are connected to automated data loggers that record measurements at configured intervals and transmit data wirelessly for remote access.

The primary value of vibrating wire monitoring in structural investigation is the ability to measure actual structural behaviour over time and compare it with predicted behaviour from structural analysis. If measured strains exceed predictions, it may indicate overloading, unanticipated load paths, or deterioration of structural capacity. If measured strains match predictions, it provides confidence that the structural model is reliable and the structure is performing as expected.

Vibrating wire gauges include integral thermistors for temperature compensation, a critical feature for long-term monitoring where thermal strains can exceed structural strains. TRSC separates thermal and structural strain components in data analysis to ensure that monitoring triggers are based on structurally significant changes rather than normal temperature cycles.