Zhuojin Pipe Fitting Co., LtdDynamic Wind Effects During Construction of Ultra-Large Transmission Steel Tube Towers
Literature Overview
This study by Zhao Jun, Du Changqing, and colleagues (2023) investigates the wind-induced dynamic responses during the construction of a 385 m tall 500 kV transmission steel tube tower in the Fengcheng-Meili Yangtze River cable crossing project in Jiangsu Province, China. The dual horizontal arm boom structure used for tower assembly exceeds 400 m in height, making wind sensitivity a critical safety concern throughout the entire erection process.
Core Technical Content
The research establishes finite element models for both the standalone boom structure and the coupled tower-boom system, then applies the harmonic superposition method to simulate wind loads and calculate wind-induced dynamic responses. The key finding is that the dynamic responses of the coupled system are consistently greater than those of the standalone boom structure, indicating that the interaction between the tower and the boom significantly amplifies wind effects.
The study compares the calculated time-history wind vibration coefficients with those specified in tall structure design codes, providing a basis for evaluating construction-phase wind safety.
Key Technical Parameters and Analysis
| Parameter | Value / Description |
|---|---|
| Tower height | 385 m |
| Boom structure height | Over 400 m |
| Voltage level | 500 kV |
| Wind load method | Harmonic superposition method |
| Coupled system response | Greater than standalone boom |
| Key indicators | Structural displacement, cable tension, wind vibration coefficient |
| Design code comparison | Tall structure design code wind vibration coefficients |
Process and Standards Analysis
The wind vibration coefficient is a critical parameter in wind load design for tall structures, as specified in standards such as GB 50009 (Load Code for the Design of Building Structures) and GB 51253 (Code for Design of Transmission Line Steel Towers). The study's comparison of calculated coefficients with code values provides insight into whether existing code provisions are adequate for the construction phase of ultra-tall steel tube towers.
From a structural engineering perspective, the coupled tower-boom system exhibits different dynamic characteristics from either component alone. The tower acts as a boundary condition for the boom, modifying its natural frequencies and mode shapes. This coupling effect is particularly significant at the highest assembly stages where the boom is extended to its maximum reach and the combined system has the greatest slenderness ratio.
The steel tubes used in such towers are typically fabricated according to GB/T 1591 or equivalent standards, with strict requirements on wall thickness tolerance, straightness, and mechanical properties. The welding quality of field-erected joints is critical, as any reduction in joint stiffness affects the overall dynamic response. Welding procedures should be qualified per NB/T 47014 or ISO 15614, and weld inspections should include ultrasonic testing (UT) and magnetic particle testing (MT) to ensure full penetration and freedom from volumetric and surface defects.
Engineering Practice Integration
The practical significance of this research lies in providing quantitative data for construction wind safety assessments. During the assembly of the highest boom position, the structural displacement and cable tension are critical safety indicators that must be monitored. The study's findings enable engineers to establish wind speed thresholds beyond which construction activities must be suspended.
The harmonic superposition method used in this study is a well-established approach for wind response analysis, but its application to the coupled tower-boom system during construction represents a specific engineering challenge. The method requires accurate determination of the system's natural frequencies and damping ratios, which can be validated through field measurements during construction.
Study Insights and Implications
This research highlights an important gap in current design codes: the construction phase of ultra-tall structures is often analyzed using simplified models that do not fully account for the dynamic coupling between the structure under construction and the erection equipment. The findings suggest that code-specified wind vibration coefficients may be conservative for the standalone boom but potentially insufficient for the coupled system. Future research should incorporate full-scale wind tunnel testing of the coupled system and develop simplified analytical methods that can be readily applied in construction planning. The results also emphasize the importance of real-time wind monitoring during construction and the need for predictive wind analysis tools that can provide advance warning of critical wind conditions.