Deep Sea Offshore Wind R&D Conference 2021 Early age ...

© ForWind1

Prof. Peter Schaumann Joshua Henneberg, M.Sc.LUH, Institute for Steel Construction 14th January 2021, Trondheim

Deep Sea Offshore Wind R&D Conference 2021

Early age movement in offshore structures with various bearing conditions

Early age movement in offshore structures with various bearing conditionsJoshua HennebergLeibniz University Hannover

Institute for Steel Construction

Outline

© DOTI/alpha ventus

Motivation Early age movement Joint research project

Seastate simulations and boundaries Monoplies Jacket structures OWT Jacket structures OSS

Summary and outlook

2



Motivation

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Movements in the material during curing

Movements due to variable loading conditions

Strength development duringcuring

E.g. sedimentation and segregation

Bond defects

What is early age movement (EAM)?

3

Sleeve

PileFluid grout material

Grouting procedure



Joined research project GREAM

© eon

Material

Local simulations

Global simulations

Experiments

Institute of Material Science


4



Joined research project GREAM

© eon

© eon

Material

Local simulations

Global simulations

Institute of Material Science

Experiments


5



Motivation


© eon

© eon

2016

No strict limits

Axial relative movement <1mm

Axial Relative movement <1mm

2014

DNV / DNVGL

< 1mm

Strict limit due to small amount of tests (primarily 35 years ago)

Influence of horizontal movement not investigated

6



Offshore structures with grouted connections


© eon

© eon

Offshore wind turbines Converter platforms

7





© eon

© eon


8





© eon

© eon


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• Positioning and leveling (using brackets “ hydraulic jackups”)

Installation procedure

Brackets

Installation weather window:

Hs = 0.5 - 3mT = 5.6 – 8.47s

© KCI

10

© Jumbo



Ring flange(300mm x 175mm)

Top view

L TP

Side view

MSL

B = Brackett = wall thicknessD = diameterLTP = transition piece lengthLG = grout length

B1t

120°

B2D

Lg

B3B1B2B3

B3

B4

B160°

B2

B5

B6

B4B5 B6

Early age movement in monopile structures


© eon

Geometry

11

Ring flange(300mm x 175mm)

Top view

B1B2

B3

L TP

Side view

MSL

B = Brackett = wall thicknessD = diameterLTP = transition piece lengthLG = grout length

B1t

120°

B2D

Lg

B3





© eon

ANSYS AQWA + ANSYS Mechanical

(1)(1) (2)

Δuradial

12

uradial [mm]





Brackets

(2)(1) (2)

Δuradial

13

ANSYS AQWA + ANSYS Mechanical

uradial [mm]




© eon

© eon

𝜂𝜂 =𝑀𝑀𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝑀𝑀𝑆𝑆𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷

≤ 1.0 𝜂𝜂 =𝐹𝐹𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐹𝐹𝑆𝑆𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷

≤ 1.0

14

Short grout length and TP length





© eon

© eon


15





© eon

© eon


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Early age movement at jacket structures of OWT


© eon

• Positioning and leveling (using brackets “ hydraulic jackups”)

Installation procedure

© IHC IQIP

• Embracing (pile gripper, horizontal brackets, wedges and grout plugs)

Stopper

Pile gripper© Boskalis

17




Simulation ANSYS WB

Stoper

Grout seal

Foundation pile

Mud line

MSL

EAM

System and boundaries

22m

42m

60m

Mud lineFoundation pile

Stopper

0° 45°

18

EAM



Summary

Magnitude >1mm up to several milimiters (Hs = 3m )

Monopiles: larger transition pieces toppling (-) local deformations (+)

Increase structural stiffness is favourable

Analyses of early age movement according to current guidelines for kind and magnitude in different offshore wind structures

greater wall thickness better than greater diameter

General trend to slender/optimized as well as increasing

structures lead to increasing EAM

22



Outlook

Further experimental investigations on EAM

What is needed to withstand occurring problems?

Depiction of fluid grout resistance in

on-bottom simulation

Submodelling and spring / damper approach

23


Institute for Steel Construction24

Thank you for your interest !Prof. Dr.-Ing. Peter Schaumann [email protected]

Joshua Henneberg, [email protected]

Leibniz University HannoverInstitute for Steel ConstructionAppelstraße 9A30167 Hannover

https://www.stahlbau.uni-hannover.de/en/

https://www.bam.de/Navigation/DE/Home/home.html

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Deep Sea Offshore Wind R&D Conference 2021 Early age ...

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