Wind Resistance Analysis of Concrete-Filled Steel Tube Transmission Towers Based on ANSYS

Literature Overview

Gong Jing, Li Jia, and Miao Yuan (2014) published their study in Water and Power Resources and Electric Power Science, analyzing the wind resistance performance of concrete-filled steel tube transmission towers using ANSYS structural analysis software. The research was conducted at Northeast Electric Power University and Evergrande Real Estate Group Hefei Company. This work addresses the practical challenge of designing transmission towers that can withstand high wind loads, particularly in large-span applications.

Composite Material Property Calculation

The study begins with the calculation of composite material mechanical parameters for CFST members. The equivalent elastic modulus and Poisson's ratio are derived from the individual properties of steel and concrete:

The equivalent properties are assigned to the finite element model to represent the composite behavior of CFST members. This approach simplifies the analysis while capturing the essential mechanical characteristics.

Finite Element Modeling Strategy

The transmission tower model employs a combination of beam elements and truss elements to represent different structural components:

1. CFST columns — Modeled as beam elements with composite material properties to capture bending behavior.
2. Bracing members — Modeled as truss elements to represent axial force transfer.
3. Joints — Represented with appropriate connectivity to ensure load transfer accuracy.

The modeling approach balances computational efficiency with structural fidelity. Beam elements provide the necessary degrees of freedom for bending analysis, while truss elements efficiently model axial members.

Modal Analysis Results

The modal analysis identifies the natural frequencies and mode shapes of the transmission tower. Key findings include:

The first mode is most critical for wind response, as it aligns with the primary wind direction. The natural frequency determines the tower's susceptibility to vortex-induced vibrations and galloping.

Wind Load Time-History Analysis

The wind load time-history analysis simulates realistic wind conditions including:

• Mean wind speed — Based on site-specific wind data.
• Gust factor — Accounts for short-term wind speed fluctuations.
• Turbulence intensity — Represents atmospheric turbulence characteristics.
• Wind direction variation — Captures directional changes over time.

The analysis reveals that concrete filling significantly increases the tower's stiffness, resulting in:

• Reduced top displacement — The tower top deflects less under wind loading.
• Higher natural frequencies — The stiffer structure responds differently to wind excitation.
• Improved overall stability — Reduced risk of wind-induced instability.

Engineering Implications for Transmission Tower Design

The study demonstrates that CFST construction offers substantial advantages for large-span transmission towers:

1. Stiffness enhancement — Concrete filling increases column stiffness by a factor that depends on the concrete-to-steel ratio.
2. Displacement control — Reduced top displacement improves conductor clearance and reduces dynamic loading on insulators.
3. Durability improvement — Concrete protection reduces corrosion risk for steel members exposed to atmospheric conditions.

However, the increased weight from concrete filling must be considered in foundation design and seismic analysis. The additional mass can increase inertial forces during earthquakes, requiring careful evaluation of the overall structural performance.

Methodological Considerations

The ANSYS-based analysis provides valuable insights but has limitations:

• Linear elastic assumption — The analysis assumes linear material behavior, which may not capture post-yield response under extreme wind events.
• Simplified composite modeling — The equivalent material approach does not account for interface behavior between steel and concrete.
• Wind load simplification — Real wind fields are highly complex and may not be fully captured by the time-history simulation.

Study Insights and Outlook

This research validates the use of CFST construction for transmission towers, demonstrating improved wind resistance through increased stiffness and reduced displacement. Future work should extend the analysis to nonlinear behavior, investigate seismic-wind combined loading, and develop design guidelines for CFST transmission towers. The findings provide a basis for optimizing tower design to balance material efficiency, wind resistance, and cost-effectiveness.