Wave forces on slender piles within pile groups: laboratory tests and prediction formulae for design practice
Bonakdar, L. (2018). Wave forces on slender piles within pile groups: laboratory tests and prediction formulae for design practice, in: PIANC Yearbook 2017. pp. 33-48 In: (2018). PIANC Yearbook 2017. PIANC: Brussels. , more |  |
| Author keywords | Pile group effect; Pile group arrangement; Relative spacing; KC number; Hybrid M5MT-GP |
| Abstract | Wave-induced loading of slender piles is among the most uncertain issues in the design of pile group-supported marine structures. Though the correct estimation of the wave loading of a pile within a pile-group in different arrangements is crucial for both safety and costs, no reliable wave load formula is available in the current guidelines and standards for the design of offshore structures. Therefore, new wave load formulae are proposed in this paper which are derived from systematic laboratory tests on the pile group effect on the wave loading of a slender pile within the author’s PhD research at Leichtweiss-Institute (LWI), Technische Universität Braunschweig, in Germany. The experiments, with a focus on regular non-breaking waves, include different pile arrangements (single, side by side, tandem, 2×2 and staggered with relative spacing of SG/D=0.5 – 5) and cover a wide range of KC-numbers (KC=1-88) and relative water depths (h/L= 0.042 - 0.64). The new wave load formulae, developed using a so-called Hybrid M5MT-GP model, allow us to systematically account for the pile group effect (KG) as a function of the flow regime (KC number) and the relative spacing (SG/D) for each tested pile group arrangement. The results show that the pile group effect needs to be considered in calculating wave loads on the slender piles in pile groups, unless KG=1, meaning that there is no interference effect between neighbouring piles and that each pile in the group can be treated as a single isolated pile. |
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