New Measurement System deployed for BreaKin JIP tests
To facilitate the ever-growing requirements concerning measurement quantity and quality, MARIN has recently deployed the new MARIN Measurement System 2 (MMS2). This system facilitates the measurement of an increased number of channels at higher sampling frequencies. Jule Scharnke,
j.scharnke@
marin.nl
Wave impact loading on offshore structures
The BreaKin JIP was one of the first projects to take advantage of the new measurement capabilities. With MMS2, a total of 125 channels were recorded at over 19kHz. The new system successfully captured the loading characteristics of breaking waves impacting a fixed platform deck in all their detail.
BreaKin is a joint research initiative addressing wave impact loading on offshore structures due to deepwater BREAKing waves and their KINematics. One of the objectives is to get more insight into the scale effects involved in wave-in-deck model tests, as it is suspected that these may lead to an overestimation of the prototype loading. To examine how conservative load measure-
ments are, model test data of the highest possible level of accuracy is required. Therefore, in March, the first set of wave- in-deck model tests of the JIP were carried out using MMS2.
During the measurement campaign in our Depressurised Wave Basin, wave impact loads on a fixed platform deck were measured at scale 1:25. Our aim was to evaluate the loading processes of both horizontal and vertical loads on the deck structure to de- termine possible sources of scale effects. The large model tests were carried out with a variation of near-breaking to breaking focused waves with crest heights up to 22.5 m, in atmospheric condition, as well
as scaled, depressurised conditions. To be able to study the detailed physical loading processes during the wave impacts, a large number of force panels and pressure cells were placed on the deck box and measured at high sampling rates. This required a large number of MMS2 conditio ning modules (see adjacent MMS2 article) connected in one measurement setup and properly synchronised.
The BreaKin JIP is the first project where we have used MMS2 to carry out such an extensive number of measurement channels and sampling rates. The tests were success- ful and all the measurements were recorded in line with our expectations.
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