鋼管混凝土轉接頭(Transition Piece / Grouted Connection)被廣泛應用於離岸工程，如:石油、天然氣及風力發電等重大海事工程，並在結構中扮演重要的傳遞力量之角色，負責將上部結構的自重與載重傳遞至下部基礎。
本文藉由有限元素軟體ABAQUS輔助模擬鋼管混凝土接頭的力學行為，並針對鋼管內無設置剪力釘的構件型式，在承受軸向力作用的情況下，探討鋼管與混凝土間的機械咬合行為。本文嘗試呈現鋼管因製作工藝而生成之微小尺寸誤差，而使構件獲得的承載能力，再經由與實際實驗數據的比對，驗證分析的可行性。因此由鋼管表面起伏誤差量值之合理範圍內，透過常態分佈之機率模式隨機取值，以及在相同範圍內只取單一代表值等兩種方式，模擬鋼管表面之微觀不平整情形。
最後由模擬結果提出建議之起伏誤差代表值，以及起伏誤差點的佈設間距，以利未來對於鋼管混凝土轉接頭分析模擬之模型建立。
並由與實際實驗結果吻合的模型，再進一步探討鋼管混凝土接頭，其混凝土之幾何尺寸變化對構件軸向承載力的影響。

Finite element analysis of Concrete-filled double skin Connecting tube for offshore wind turbine

Yi-Cheng Hung
Hsuan-Teh Hu
Department of Civil Engineering National Cheng Kung University

SUMMARY

Transition piece (Grouted connection) is widely used in offshore engineering, e.g., wind power, oil and gas, and act as an important part to transit the loading from superstructure to foundation.
In this thesis, I use the finite element analysis software, ABAQUS, to simulate the behavior of grouted connections when subjected loading. The thesis try to show the slightly rise and fall on the surface of steel tube due to produce, which cause the member to gain the loading capacity. For simulate the condition of slightly rise and fall on the surface of steel tube, we arrange some assistant points on the surface of steel tube. The value of assistant points were picked from reasonable range, and picked by normal distribution method or choose only one value as representation.
Finally verify the feasibility of this simulation by compare the result with the conclusion of experiment, and to propose a representative value to exhibit the roughness of the surface of steel tube.
At the end of this thesis, further studying the effect on the difference of the length of transition piece.

Key words : Transition piece, Grouted connection, ABAQUS

Introduction

The energy resources in Taiwan is mainly depend on nuclear power and thermal power. Now, Taiwan is going to expand green power, and wind power is one of the green powers be emphasized, it’s expect to reach 12,502MW of total capacity in 2030, including 5MW offshore wind turbines 600 sets and 2.5MW onshore wind turbines 450 sets, and the offshore wind farm is located at Chang-Hua, Yun-Lin and Peng-Hu.

Materials and methods

The type of foundations of offshore wind turbine is depend on the condition of the sea which wind farm locate, even though the depth in the Taiwan strait is between 15m ~ 20m, it is well suited to mono-pile foundation, but after consider the weak seabed of Taiwan strait, and offshore construction ability, finally select the Jacket foundation (Group piles) as design.
This thesis use finite element software, ABAQUS, to simulate the loading behavior of transition piece, we set up the model refer to the scale of reality experiment, and compare the result of simulation with the data of experiment.

Results and discussion

The simulation show that if the assistant points distributed to a specific span, and the magnitude of rise and fall is setting in a specific value, then the result of simulation approach the experiment that is done by Peter Schaumann (2010).
This thesis keep on studying the effect on the difference of the scale of transition piece, and the effect on the difference of the strength of materials. We discuss four different values of length of transition piece (L_G), and four different values of thickness of transition piece (t_G). The result show that the loading capacity of transition piece is direct proportion with the length of transition piece, but the effect of the thickness of transition piece is not that simple, with increased the thickness of transition piece, the loading capacity will raise up first, and fall down after reach a peak value.

Conclusion

After testing, we found that if the model set up without assistant points, the transition piece may punching directly when loading comes up, it is almost no loading capacity.
We think the roughness of the surface of steel tube is the key point to lead to friction, in order to show the behavior of roughness, not only the friction coefficient of material should be set, but also the rise and fall of the surface of steel tube should be simulated.
After our simulation and compare the result with experiment, the model can approach experiment when the ratio of number of assistant points (N) and length of transition piece (L_G) equal to 0.5, and the rise and fall of the surface of steel tube set to 0.0266 mm.

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