Laser Vibrometer Inspection of Suspender Cables
Locating tensile forces on bridge cables using laser vibrometry.
Determining load analysis is conducted to determine the actual tension forces of the suspension cables under dead load conditions.
Our infrastructure uses cable for many structures including power lines, radio towers, ski lifts, and bridge cables. The health of these cables is critical to the overall health of the structure it is supporting. Inspecting the consistent tension of suspension cables will help maintain the health of the structure and the safety of the traveling public.
The Laser Doppler Vibrometer (LDV) measures vibration based on the detection of the doppler shift in the frequency of a laser beam reﬂected from a moving target.
A Laser Vibrometer only requires pointing the laser beam onto the location where the measurement shall be taken.
The measurement is contactless and locations up to 200m (600ft) distance can be measured without physically attaching any device or target to the object of interest.
This allowed for very quick mobilization on-site and a very fast production rate, executing the measurements.
LDV takes a measurement of the vibration signature of each bridge cable at night time to reduce the influence factor of traffic load. It uses forced excitation to reduce the measurement time to a minimum and to allow excitation of multiple modes.
Infraspect uses a stochastic subspace identification method (SSI) to overcome the frequency resolution limit of an FFT analysis unless very long measurement intervals are selected.
Non-contact laser vibrometry provides a cost-effective, rapid, and accurate force measurement to ensure cable safety.