High Frequency Testing Facility for Stay Cables and Tendons

Fatigue is an important cause of failure in mechanical components and structures that are subjected to repeated loads. The testing of structural components under cyclic loading constitutes one of the most important fields of experimental mechanics. The testing of specimens with 2 to 20 million load cycles is only feasible for small specimens, and not for large structural elements. Usually, conventional servo-hydraulic testing machines are used; thus, time to carry out the experiments as well as the energy consumption increase dramatically with specimen size. A new approach to the testing of large structural elements by taking advantage of the resonance effect is shown in this paper. For example, a fatigue experiment on a stay cable for a bridge takes 3 to 4 weeks by using conventional servo hydraulic controlled jacks. The approach developed at the Institute for Structural Engineering at Vienna University of Technology reduces testing periods by a factor of 20 to 50 and the required energy input for a fatigue test by a factor of more than 1000. A testing unit dimensioned for a static tensile load up to 20 000 kN and an upper load for fatigue tests up to 10 000 kN was built at the Vienna University of Technology in 2006.