Wind Vibration Control of 1000kV Huainan-Shanghai Double-Circuit Steel Pipe Tower

Literature Overview

The paper by Yang Jingbo, Han Junko, Hua Xugang, and Chen Zhengqing (2010), published in the Proceedings of the CSEE, addresses wind-induced vibration control for the 1000kV Huainan-Shanghai (Wandian Dongsong) transmission and transformation project. Funded by the National Natural Science Foundation of China (Grant No. 50808079), this research targets two distinct vibration modes: global tower vibration in the along-wind direction and local tube member vortex-induced vibration in the cross-wind direction. The proposed control strategies combine numerical simulation with wind tunnel testing to develop practical engineering solutions.

Vibration Problem Analysis

The 1000kV extra-high voltage steel pipe tower presents unique vibration challenges due to its large span, significant height, and slender tubular members. The overall tower structure is susceptible to bending and torsional vibrations in the along-wind direction, while individual tube members experience cross-wind vortex-induced vibrations (VIV) when wind flows perpendicular to their axis. Both vibration types can lead to fatigue damage, accelerated corrosion, and reduced service life if not properly controlled.

The dual vibration problem requires a comprehensive control approach because the global and local vibrations interact. Global tower motion modifies the relative wind velocity experienced by individual tube members, potentially intensifying VIV. Conversely, local VIV in individual members contributes to the overall dynamic response of the tower structure.

Global Vibration Control Strategy

The proposed joint control scheme for global tower vibration combines two complementary damping systems. Viscoelastic dampers are installed in parallel with the main steel pipe members on the outer surface to control bending vibrations. These dampers provide frequency-dependent damping that is particularly effective for the lower-frequency bending modes of the tower. The viscoelastic material exhibits high loss factor over a broad frequency range, making it suitable for the multiple bending modes excited by turbulent wind loading.

Tuned mass dampers (TMDs) are positioned at the cross-arm tips to control torsional vibrations. The TMDs are tuned to the primary torsional frequency of the tower and provide targeted damping for this specific mode. The cross-arm tip location is optimal for TMD placement because the torsional mode shape exhibits maximum displacement at these locations, providing maximum control efficiency.

The design methodology for the control devices includes determination of the required damping ratio, selection of the damper natural frequency for TMDs, and specification of mass ratios. The viscoelastic damper design must account for the wide temperature range experienced by the tower, as viscoelastic material properties are highly temperature-sensitive.

Local VIV Control Strategy

Helical strakes are proposed as the control measure for cross-wind vortex-induced vibration of individual tube members. Helical strakes are spiral-shaped appendages wrapped around the tube member that disrupt the regular vortex shedding pattern responsible for VIV. By breaking up the coherent vortex structures, helical strakes prevent the synchronization between vortex shedding frequency and the structural natural frequency that causes VIV.

The key design parameters for helical strakes include the helix pitch (axial distance between consecutive turns), the strake height (radial extent from the tube surface), and the number of strakes per unit length. The pitch must be selected to ensure that the vortex shedding wavelength does not coincide with the structural wavelength. Too large a pitch may be ineffective, while too small a pitch increases drag and construction complexity.

Wind Tunnel Test Results

The wind tunnel testing validates the effectiveness of the proposed control measures. The test results demonstrate that under appropriate parameter configurations, the along-wind displacement and acceleration response at the tower top can be reduced by approximately 30%. The cross-wind vibration of individual tube members is essentially eliminated with the helical strake installation. These results confirm that the combined control strategy effectively addresses both vibration types simultaneously.

Engineering Practice Implications

The proposed control measures are designed for practical engineering application. The viscoelastic dampers can be installed during tower assembly without requiring major structural modifications. The TMDs at cross-arm tips utilize existing structural elements as mounting points. The helical strakes can be applied to existing tube members through external attachment methods. This practical approach minimizes additional construction costs while providing significant vibration reduction.

From a steel pipe manufacturing perspective, the helical strake installation requires careful consideration of the tube surface condition. The strakes must be securely attached to the pipe surface, and any attachment method should not compromise the pipe's structural integrity or corrosion protection. The additional drag from helical strakes increases the wind load on the tower, which must be incorporated into the overall structural design.

Study Insights and Reflections

This research demonstrates the importance of addressing both global and local vibration modes in extra-high voltage transmission tower design. The combined control strategy of viscoelastic dampers, tuned mass dampers, and helical strakes provides a comprehensive solution that addresses the full spectrum of wind-induced vibration problems. The 30% reduction in global vibration response and near-complete elimination of local VIV represent significant improvements in tower fatigue life and operational reliability.

The research methodology, combining numerical simulation with wind tunnel testing, provides a rigorous validation approach for vibration control design. The practical implementation considerations ensure that the proposed solutions are feasible for real-world application. For future extra-high voltage transmission projects, the findings of this research should serve as a baseline for vibration control design, with modifications tailored to specific site conditions and tower configurations.