Fatigue testing of large-scale steel structures in resonance with directional loading control
In: Procedia Structural Integrity. Elsevier B.V.: Amsterdam. ISSN 2452-3216, more
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fatigue testing; resonance; resonant bending; steel; jacket; beam; pipeline; large-scale testing |
| Authors | | Top |
- Van Wittenberghe, J., more
- Coste, A.
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| Abstract |
Offshore structures such as jacket and monopile foundations for wind towers and platforms for oil and gas are large steel structures that are subjected to severe fatigue loading conditions. When developing constructions using novel welding techniques, high-strength steel grades or specific bolted assemblies there is a need for validation testing of large-scale components. Conventionally, such fatigue tests are carried out on servo-hydraulic test which are time-consuming.Alternatively, fatigue tests can be performed in resonant bending by a cyclic excitation force with frequency close to the first eigenfrequency of the test specimen. In this paper a new test setup is presented suitable for testing large-scale steel components in resonance with control of the loading direction by two counter-rotating excentric masses.A wide range of loading conditions can be applied with a frequency from 20 to 40 Hz. The test specimen, that can weigh up to 25 ton, is supported in the nodes of its natural wave-form, so that no dynamic forces are transmitted to the setup.The working principles of the test setup are illustrated based on test results of a 711 mm diameter x 25.4 mm wall thickness steel pipe, a welded X-node representative for a welding detail of an offshore jacket foundation structure and a large-scale HE-beam. Crack initiation is detected using acoustic emission while crack growth is monitored by local strain gauge measurements as well as the global stiffness reduction of the test specimen. Finally, the beach marking method is used to visualize crack fronts for post-mortem analysis. |
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