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In recent years, the advancement of steel structure application technology in China has led to significant development in economical profiles such as cold-formed thin-walled steel. Compared to traditional rolled sections, cold-formed steel offers a more rational material distribution across its cross-section, higher radius of gyration, and improved resistance to both bending and torsion. Unlike hot-rolled steel, which increases load capacity by adding more material, cold-formed steel enhances performance and saves material by optimizing its cross-sectional shape.
One of the key advantages of cold-formed steel is its economic section characteristics. In the context of transmission towers, the web often experiences instability due to its large slenderness ratio. Traditional angle sections lack clear advantages in this regard and have limited available specifications. Cold-formed steel, however, allows for the selection of appropriate cross-sections based on the structural forces acting on each member, making full use of its section properties to achieve greater efficiency and cost-effectiveness.
Another benefit is the flexibility in product specifications. A conventional 10-ton transmission tower may require up to 25 different types of angle steels, leading to challenges in sourcing a wide range of small-batch profiles. This often results in material substitution, causing up to 10% waste in processing. In contrast, cold-formed steel can be produced in various sizes using simple equipment like a cold rolling mill, ensuring a steady supply without limitations on quantity or size.
The variable dimensions of cold-formed steel also offer significant advantages. A typical 10-ton tower consists of nearly 2,000 components with varying lengths. Hot-rolled steel, being a fixed-size product, often leads to material waste, with up to 5% loss due to length mismatches. Cold-formed steel, however, can be manufactured to meet exact user requirements, achieving a high finished product rate (up to 99%) and minimizing material waste during the fabrication process.
Additionally, the diverse cross-sectional shapes of cold-formed steel provide design flexibility. Unlike angle steel, which restricts tower designs to square or rectangular forms, cold-formed steel enables more innovative and efficient structures. It allows for optimized web systems and reduces the number of components, ultimately lowering the overall weight and material usage.
High-strength cold-formed steel also addresses the challenges associated with traditional hot-rolled steel, such as limited supply and complex manufacturing processes. Moreover, while hot-dip galvanizing is commonly used for corrosion protection in transmission towers, it is not always suitable for cold-formed steel due to its varied cross-sections and thin profiles. However, emerging anti-corrosion technologies, such as weather-resistant materials and advanced plating methods, are now offering effective solutions for cold-formed steel.
The production of high-strength weathering steel has become increasingly mature, with widespread use in railway systems. Applying this material to transmission towers not only reduces the need for anti-corrosion treatments but also lowers costs by about 20% per ton, providing substantial economic and environmental benefits.
Although research into the use of cold-formed steel in transmission towers began in the late 1980s, early adoption was limited due to high costs and technical constraints. However, with the rapid development of steel structure technology in China, the consumption of these economical profiles has grown significantly, and their processing costs have decreased. The superior performance of their cross-sections has made them increasingly viable for use in transmission towers.
Using cold-formed thin-walled steel helps conserve resources and energy. Promoting high-strength weather-resistant cold-formed steel on transmission towers can reduce tower consumption, lower processing costs, and minimize environmental impact. This makes it an economically and environmentally beneficial solution that deserves further exploration and application.