Wind Power Plant with a Truss Segment Made of Fiber-Reinforced Molded Timber Pipes
An innovative research project has been carried out on the company premises of STM Montage GmbH in Lunzenau, Germany: A wind power plant with a lattice tower, where the uppermost segment consists of fiber-reinforced molded timber pipes.
|Research Project Funding||
Zukunftsinitiative Mittelstand (ZIM), Germany
German Federal Ministry for Economic Affairs and Energy (BMWi)
Funding code: KF 2132403WZ3
|Design, Structural Engineering, Execution||
Technical University of Dresden
|Execution and Assembly||
STM Montage GmbH
Thin-walled timber pipes have a low dead load and good dynamic properties. This improves the material efficiency and vibration behavior, as well as increasing the resistance to material fatigue.
The Technical University of Dresden was responsible for the design and dimensioning of the lattice tower. RSTAB structural frame and truss analysis software was used for the design.
The lattice tower is 104 ft high in total and carries the wind power plant with an output of 1.34 hp. The lowest approximately 60.70 ft of the structure consist of S235 steel pipes. The approximately 36-foot-long truss segment with molded timber pipes d = 9.45 in. and steel pipe diagonals was placed on top.
The molded timber pipes consist of pre-compressed timber panels that have been bent into thin-walled tubular cross-sections under the action of heat and steam. The Institute of Steel and Timber Construction developed this molded timber method. The structural components produced in this way have a very high load-bearing capacity with a very low dead load. A thin layer of fiber-reinforced plastics was also applied on the outside. This increases the compressive strength by up to 50% and provides the structure with protection against weathering.
The longitudinal joints of the timber columns consist of steel pipes to which the diagonals also connect. A special feature of these connections is that they were glued. Before they were used, they were extensively analyzed experimentally and numerically by TU Dresden. The analyses resulted in the limit strengths for the connections, which could be taken into account in the RSTAB calculation.
After the construction of the lattice tower, all the steel parts and transitions to the timber pipes were given an anticorrosive coating. The research project showed that molded timber pipes are very suitable as load-bearing components in tower structures subjected to vibration. The greatest advantage is the lower dead load compared to steel, and thus the reduction of the vibrating mass. In this project, the dead load of the uppermost segment could be reduced by 1.2 tons compared to steel. In addition, the damping material properties of the timber reduced the effects of fatigue on the lower structural components.
This research project was funded by the Central Innovation Programme for Small and Medium-Sized Enterprises (ZIM) of the German Federal Ministry for Economic Affairs and Energy (BMWi).
Project LocationCossener Straße 2
Do you have further questions or need advice? Contact us via phone, email, or chat or find suggested solutions and useful tips on our FAQ page available 24/7.
In RF-/FOUNDATION Pro, the foundation design requires the definition of the corresponding loading (load cases, load combinations, or result combinations) for different design situations (STR, GEO, UPL, or EQU).
For the joint components, it is possible to check whether the stability failure is relevant (requires the Structure Stability add-on for RFEM 6 / RSTAB 9).
In this case, the critical load factor for all analyzed load combinations and the selected number of mode shapes is calculated for the connection model. The smallest critical load factor is compared with the limit value 15 from the standard EN 1993‑1‑1, Clause 5. Furthermore, a user-defined adjustment of the limit value is possible. Moreover, the corresponding mode shapes are displayed graphically as the result of the stability analysis.
For the stability analysis, an adapted surface model is used to specifically recognize the local buckling shapes. The model of the stability analysis, including the results, can also be saved and used as a separate model file.
- What is the meaning of the superposition according to the CQC rule in a dynamic analysis??
- How do I display some results of all load cases in the printout report, but other results of the selected load cases only?
- Where do I find the setting to specify the entered structural component as a "wall" or "slab"?
- I would like to convert the load from a surface load to a line load, that is, to apply it to the individual beams. How can I do this without using an auxiliary area?
- I have defined temperature loads, strain loads, or a precamber. Once I modify stiffnesses, the deformations are no longer plausible.
- Is it possible to transfer properties, such as the cross-section, or the surface thickness as well as the material of a surface, of an existing element to a new element?
- How can I get the member end forces to design the connections?
- I would expect the results from my load combination (CO) set to a linear analysis to equal the summation of the results from my load cases (LC) also set to a linear analysis. Why do the results not match?
- A rigid member should only be able to absorb tensile forces or only compressive forces. What are the options for considering these nonlinearities in the calculation?
- How can I perform a stability analysis for a tapered member?