Notes in each flow of steel stairs

Steel structure production includes lofting, marking, cutting, correction and many other links. The anti-slip coefficient of the friction surface after high strength bolt treatment should meet the design requirements. Rust removal and coating shall be carried out after quality inspection. Generally, 30 ~ 50mm should be set aside for the installation weld. Welders must pass the examination and obtain a certificate of qualification, and must weld in the examination and approved scope of the item. After weld welding, welder's seal shall be made on the welds and parts specified in the process.

The welding material should match the base material. The first and second level welds with full penetration should be tested for internal defects by ultrasonic inspection. When ultrasonic inspection cannot judge the defects, radiographic inspection should be used. The steel, welding material and welding method used by the construction unit for the first time shall be evaluated for welding process. When transporting steel components, select vehicles according to the length and weight of steel components. The fulcrum of the steel member on the vehicle, the length of the extension of both ends and the binding method should ensure that the member does not deform and damage the coating. The installation of steel structure shall be carried out according to the construction organization design, and the installation procedure shall ensure the stability of the structure and not lead to permanent deformation. When installing the columns, the positioning axis of each column shall be directly led from the ground control axis. The columns, beams, roof frames and other major components of the steel structure shall be corrected and fixed immediately after they are installed in place.

The friction surface of the components processed by the factory shall be rechecked before installation, and the anti-slip coefficient shall be rechecked before installation. The fire performance of steel structure is poor. When the temperature reaches 550℃, the yield strength of the steel decreases to about 0.7 of the yield strength of the normal temperature, and the structure reaches its designed strength value and may be damaged. Design should be in accordance with the provisions of the relevant fire codes, so that the building structure can meet the requirements of the corresponding fire standards. In the time required by fire standards, the temperature of the steel structure should not exceed the critical temperature to ensure the normal bearing capacity of the structure. Exposed steel structures may suffer severe corrosion, most commonly rusting, from the atmosphere, especially polluted air. In order to ensure the normal use of steel structure, anti-corrosion treatment must be carried out on the surface of the component. The method of anticorrosive treatment is determined according to the surface conditions and service life of components.