Photovoltaic steel structure projects in high-altitude areas often face severe challenges from low-temperature environments, with steel brittleness being a core issue affecting structural safety and durability. In low-temperature environments, the toughness of steel decreases significantly, while brittleness increases. When the temperature drops to a certain critical value, the impact toughness of the steel decreases sharply, leading to brittle fracture of the structure without obvious warning. As the core carrier supporting photovoltaic modules, the safety of the photovoltaic steel structure directly affects the stable operation of the entire photovoltaic system. Therefore, a comprehensive approach involving material selection, design optimization, process control, and operation and maintenance management is necessary to effectively address the risk of steel brittleness in low-temperature environments.
Regarding material selection, steels with excellent low-temperature toughness should be prioritized. For example, low-alloy high-strength structural steel, by adding trace amounts of alloying elements, can significantly lower the ductile-brittle transition temperature and improve the steel's resistance to brittle fracture in low-temperature environments. Simultaneously, the chemical composition of the steel, especially the content of elements such as carbon, sulfur, and phosphorus, should be strictly controlled to avoid a decrease in steel toughness due to impurities. Furthermore, for critical components or structures subjected to dynamic loads, special steels with higher toughness can be selected, such as high-toughness steel for bridges, whose ductile-brittle transition temperature can be as low as required in extremely cold environments, providing reliable safety assurance for photovoltaic steel structures.
Design optimization is a key aspect of avoiding cold brittleness in steel. In structural design, stress concentration should be minimized, and sharp notches or abrupt changes in cross-section should be avoided to reduce local stress levels. For welded structures, welds should be rationally arranged to avoid excessive concentration or intersections, reducing the impact of residual welding stress on structural toughness. Simultaneously, measures such as rounded transitions and the addition of reinforcing ribs can be adopted to improve the overall resistance to brittle fracture. In addition, the impact of low-temperature environments on structural performance should be fully considered during design, and methods such as low-temperature fatigue life assessment and fracture mechanics analysis should be used to ensure the safety of the structure under extreme conditions.
Process control is an important means of ensuring the low-temperature toughness of photovoltaic steel structures. During welding, welding process parameters, such as preheating temperature, welding current, and welding speed, should be strictly controlled to ensure weld quality. For thick plate welding, layered welding and preheating followed by postheating should be employed to reduce residual welding stress and prevent cracking. Simultaneously, welding rods matching the base metal should be selected to ensure the weld metal's toughness is not lower than that of the base metal. During cutting, milling, and other machining processes, sufficient shrinkage gaps should be reserved to prevent work hardening and subsequent decrease in steel toughness. Furthermore, quality inspection during construction should be strengthened to promptly identify and address potential defects, ensuring the structural quality meets design requirements.
Operation and maintenance management is a crucial aspect of ensuring the long-term safe operation of photovoltaic steel structures. In high-altitude areas, regular inspections of photovoltaic steel structures should be conducted, focusing on critical areas such as welds and bolted connections, promptly identifying and addressing defects such as cracks and corrosion. Comprehensive operation and maintenance records should be established, documenting the structural operating status and maintenance history to provide a basis for structural safety assessments. Under extreme weather conditions, enhanced structural monitoring and temporary reinforcement measures should be implemented to ensure structural safety.
In addition, considering the unique environment of high-altitude areas, auxiliary measures can be taken to enhance the resistance to cold brittleness of photovoltaic steel structures. For example, coating the structural surface with anti-corrosion paint reduces the degradation of steel performance caused by corrosion; installing heating devices inside the structure raises the structure's temperature level in low-temperature environments, reducing the risk of cold brittleness. Although these measures increase costs, they significantly improve the reliability and durability of the structure, providing a strong guarantee for the long-term stable operation of the photovoltaic system.
