Portal frames are a classic structural system widely used in modern construction. The main upper structure consists of a rigid frame beam, columns, bracing, purlins, tie rods, and gable frames, among other components. The steel portal frame system is known for its simple load distribution, clear structural path, fast manufacturing of components, and ease of factory production, which significantly reduces the overall construction time. Due to these advantages, it has become a popular choice for industrial, commercial, and public buildings such as warehouses, factories, shopping centers, and cultural facilities. Originating in the United States over a century ago, the steel portal frame has evolved into a highly standardized system with well-established design, fabrication, and construction practices. Its efficiency and adaptability have made it one of the most commonly used structural solutions in contemporary architecture. Color haze meter,LCD panel haze meter,Spectral transmittance haze meter CHNSpec Technology (Zhejiang)Co.,Ltd , https://www.chnspec360.com