Institute of Reinforced Concrete Structures and Building Materials - Departement of Reinforced Concrete Structures


Assessment of the condition of external tendons, stay cables and other guyed structures using vibration measurement

Nondestructive determination (NDT) of the condition of external tendons and stay cables using a patented analysis of the eigenfrequency. The road network of Germany comprises about 40,000 bridges. These bridges are exposed to a high stress due to the increased traffic. To detect bridge damage early, regular inspections are necessary. Currently, here are almost exclusively visual methods used. The disadvantage is that the damages can be detected only if they are relatively advanced. Our rapid test for in-situ inspection of external tendons and stay cables offers an inexpensive and meaningful alternative.

An examination of external tendons in hybrid towers of wind power plants can also be performed. At wind power plants the external tendons are placed almost vertically. Due to their length (partially over 100m) and installed turning points they are not meaningful verifiable with other methods.

  • Detection of the frequency spectrum with very high accuracy
  • Measurement of external tendons
  • Measurement of stay cables and other guyed structures
  • Data acquisition per measuring point within a few minutes, including installation and removal of the sensor
  • Recording of measured values without the need for the presence of specialists
  • Instruction of measuring staff (e.g. bridge inspector) in one-day training
  • Achieving a comparability between different tendons and different bridges respectively wind power plants
  • All data are saved at a central point
  • Comparability given by regular measurements
  • At bridges as part of a major testing every 6 years according to DIN 1076
  • for wind power plants for periodic inspections 
  • Measuring instrument (Fieldbook) can be used by touchscreen as notebook (Windows OS)


Keywords: building inspection, bridge construction, inspection, monitoring, external tendons, stay cables, state examination, frequency determination, frequency analysis, tension force, actual state, in situ, wind energy plant, wind energy plants, ResoCable, ResoBridge