Wind Vibration Performance of Hollow Interlayer Steel Tube Concrete Wind Turbine Towers

Literature Overview

This paper by Wang Wenda, Zhang Lili, Ji Sunhang, and Shi Yanli from Lanzhou University of Technology investigates the wind vibration performance of Hollow Interlayer Concrete Filled Steel Tube (CFDST) wind turbine towers. Published in the Journal of Architecture and Civil Engineering (Vol. 40, No. 2, 2023, pp. 26-39), the research was supported by the National Natural Science Foundation of China (Grant No. 52168021) and the Gansu Provincial Construction Science and Technology Project (Grant No. JK2021-42). The study proposes a CFDST tower configuration based on load-bearing capacity equivalence with a conventional conical steel tower, establishes finite element models using ABAQUS, and compares the dynamic response characteristics of both tower types under different loading conditions.

Core Technical Findings

The CFDST tower design achieves equivalent bending load-bearing capacity and stiffness to the conventional steel tower while reducing the bottom cross-section dimensions by 25.6 percent. The CFDST tower does not resonate with the harmonic excitations generated by blade rotation, which is a critical advantage for wind turbine structural integrity.

Damping has a significant influence on the displacement, velocity, acceleration, and stress response amplitudes of the wind turbine tower. Compared with the conventional steel tower, the CFDST tower under normal operating load conditions shows reductions of 21.1 percent in peak displacement, 30.2 percent in peak acceleration amplitude, and 41.6 percent in maximum equivalent stress. Under storm load conditions, the reductions are 14.4 percent in peak displacement, 32.2 percent in peak acceleration amplitude, and 36.3 percent in maximum equivalent stress.

Key Technical Parameters and Performance Comparison

Process and Standards Analysis

The transition from conventional thin-walled steel towers to CFDST towers represents a significant structural innovation in wind turbine engineering. The conventional steel tower, characterized as a tapered single thin-walled slender structure, is inherently susceptible to large deformations and vibrations under blade rotation and wind loading. The CFDST configuration addresses these limitations by incorporating a concrete core within a steel tube framework, providing enhanced mass, stiffness, and damping characteristics.

From a manufacturing and fabrication perspective, the CFDST tower requires precise steel tube fabrication with attention to dimensional accuracy, weld quality, and surface treatment. The hollow interlayer configuration introduces additional complexity in terms of internal support structures, concrete placement access, and quality verification. The concrete placement within the hollow interlayer space requires specialized techniques to ensure complete fill without voids, particularly in the tapered geometry that may present placement challenges at varying elevations.

The finite element modeling approach using ABAQUS provides a validated analytical tool for CFDST tower design, enabling parametric optimization of tower geometry, material properties, and damping characteristics. The study's comparison methodology—establishing equivalence based on load-bearing capacity—provides a rational basis for CFDST tower design that can be extended to other wind turbine applications.

Engineering Practice Integration

In practical wind turbine engineering, the CFDST tower offers several compelling advantages: reduced cross-section dimensions enable more compact tower designs with potentially reduced transportation and installation costs; the absence of resonance with blade excitation frequencies enhances structural reliability; and the significant reduction in stress amplitudes improves fatigue performance and extends service life. The damping sensitivity finding highlights the importance of incorporating appropriate damping mechanisms in CFDST tower design, which can be achieved through material selection, structural detailing, or supplementary damping devices.

For quality control during fabrication and construction, the steel tube weld quality is critical, requiring non-destructive testing including ultrasonic testing and magnetic particle testing per relevant standards such as API 5L or ISO 15614. The concrete fill quality should be verified through density testing and ultrasonic inspection. The interface between the steel tube and concrete should be assessed for bond integrity, particularly at elevation transitions where the tapered geometry creates variable confinement conditions.

Key Questions and Reflections

The study raises important questions regarding the long-term performance of CFDST towers under cyclic wind loading and blade-induced vibrations over the 20 to 25 year design life of a wind turbine. The concrete-steel interface behavior under sustained cyclic loading, particularly the potential for progressive debonding and the effect on damping characteristics over time, warrants further investigation. Additionally, the seismic performance of CFDST towers in regions with significant seismic activity should be evaluated, as the increased mass of the concrete core may have implications for seismic response. The economic comparison between CFDST and conventional steel towers, including lifecycle cost analysis considering maintenance and replacement, should be conducted to fully evaluate the practical viability of this technology.

Study Insights and Implications

This research demonstrates that CFDST towers offer a promising alternative to conventional steel towers for wind turbine applications, providing significant improvements in dynamic response performance while maintaining equivalent load-bearing capacity. The 25.6 percent reduction in cross-section dimensions combined with the substantial reductions in displacement, acceleration, and stress amplitudes represents a meaningful advancement in wind turbine tower design. The elimination of resonance risk with blade excitation frequencies is particularly significant for structural reliability. The study provides a foundation for further development of CFDST tower technology, with the finite element modeling approach offering a practical design tool for engineers. The findings support the broader trend toward composite and hybrid structural systems in renewable energy infrastructure, where the combination of steel and concrete properties can yield superior performance compared to either material alone.