Dynamic assessment of underwater pipeline systems using statistical model updating

This paper presents a statistical model updating technique for damage detection of underwater pipeline systems via vibration measurements. To verify the reliability of the method, laboratory tests of a scaled pipeline model were carried out in a towing tank. The model includes a plastic pipe and some removable springs which are designed and fabricated to link the pipe and the steel base to simulate the bedding conditions. Different damage scenarios, in terms of location and severity of scouring under the pipe, were simulated by removing one or several springs. The natural frequencies, damping ratios and mode shapes of the pipeline system were extracted from the measured vibrations using a stochastic subspace identification technique. Both the numerical and the experimental results show that the method is effective and reliable in identifying the underwater pipeline bedding conditions and the damage in the pipe structure.