Session: 02-09-01 Extreme Loading and Responses 1

Paper Number: 80945

80945 - Estimation of Design Slamming Loads From Laboratory Test of a Circular Cylinder 

NOTE: This paper was sent to the OMAE 2020 but not presented due to the Covid 19 issue. Note also that a similar abstract was sent this year, but one co-author was missing so therefore this is resent.

Slamming from steep breaking waves can give high impact loads, both globally and locally. Marine structures that can be exposed to slamming loads need to be designed to withstand these loads. However, there are several challenges related to estimating these loads. Slamming load is highly non-linear, and the impact loads from apparently similar wave profiles show a large scatter in load level.
Slamming loads from irregular steep breaking waves are of a stochastic nature and need to be treated statistically. The probability distributions of the slamming loads need to be established from a rather large number of realizations in realistic sea state conditions. The most common way to estimate the slamming load from steep irregular breaking waves is through laboratory experiments in small scale.
Model tests are normally performed in unidirectional sea. Regarding the impact problem, this is assumed to be slightly conservative. Previous laboratory tests have measured very large slamming loads from breaking waves in unidirectional sea. Real seas will always have some directional spread. In this paper the effect of short-crested waves on the q- probability slamming load is estimated from a small-scale laboratory experiment.

The experiment was performed in scale 1:100. Slamming loads were measured on a bottom-fixed circular cylinder with a diameter of 310 mm in a water depth of 1.25 m. The slamming force was measured on 56 individual panels of 30 mm x 30 mm.

About 850 irregular wave tests in both unidirectional and directional spread waves, were performed. The tested sea states were selected to represent realistic North Sea wave conditions. Eleven different combinations of Hs and Tp were tested. 

Presenting Author: Gunnar Lian Equinor

Authors:

Gunnar Lian Equinor
Sverre Kristian Haver University of Stavanger
Chris Swan Imperial College