The cold winter is coming soon, which is not good news for the construction of steel structure engineering. Once frozen, the outdoor works can only be stopped.There are many problems in winter construction, so special attention should be paid to the construction of steel structure workshop in winter. When the steel structure project is constructed under negative temperature, the characteristics of materials used and temperature requirements should be considered. The deviation should be adjusted timely. The construction should be carried out in strict accordance with the process regulations and implementation plan, and attention should be paid to the construction safety　　

 1、 Hidden dangers of steel structure construction in winter:

 　　1.The coating quality of steel structure is affected.Some paint industry personnel pointed out that the construction temperature of paint is very good, not less than 5 degrees, because the steel structure in winter roll coating prone to bubbles, and affect the adhesion of the paint film, thus reducing the coating fire and anti-corrosion ability. 

Hidden danger of steel structure construction in winter

　　2.It affects the flexibility of construction personnel, thus affecting the construction quality and construction period. 　　

 　　3.The welding difficulty and construction steps are increased. 　　

 　　4.When the component is manufactured at positive temperature or installed at negative temperature, it is easy to shrink due to the stable change of environment. 　　

2、 Construction measures of steel structure engineering in winter:　　

 　　1.The fabrication and installation of steel structure in winter construction shall be carried out in strict accordance with relevant regulations on winter construction of steel structure.　　

 　　2.When steel members are installed above or below zero degree centigrade, the shrinkage of steel members should be considered according to the difference of ambient temperature, and the deviation adjustment measures should be taken in construction. 　　

 　　3.Welders who participate in the construction of steel structure below zero ℃ shall be trained in negative temperature welding process and have corresponding operation certificate. 　　

 　　4.The steel and relevant connecting materials used at negative temperature shall be attached with quality certificate, and the performance shall meet the requirements of design and product specifications. 　　

 　　5.The welding rod used below 0 ℃ shall not be exposed for more than 2 hours, and shall be baked again after 2 hours. The welding rod shall be baked for no more than 3 times. 　　

 　　6.The flux shall be baked according to the regulations before use to make its moisture content not exceed 0.1%. 　　

 　　7.High strength bolts used below zero ℃ must have product certificate, and the torque coefficient and axial force shall be rechecked under negative temperature. 

Construction measures of steel structure engineering in winter

　　8.Water based coatings shall not be used for steel structures below 0 ℃. 　　

 　　9.The shrinkage allowance shall be reserved during the cutting of components, and the welding shrinkage and compression deformation shall be coordinated with the shrinkage deformation of steel below zero ℃. 　　

 　　10.During the assembly of components, the assembly shall be expanded from the inside to the outside according to the sequence specified in the process, and the weld shrinkage value to be reserved shall be determined by test during the assembly at negative temperature. 　　

 　　11.During the component assembly, the rust, burr, soil, oil stain, snow and other debris left in the joint shall be removed to keep the joint dry without residual moisture. 　　

 　　12..Multi layer welding shall be adopted when welding steel plate above 9mm below zero degree centigrade. The welding seam shall be overlaid layer by layer from bottom to top. Each welding seam shall be welded at one time. If the welding is interrupted, the welding defects shall be removed before welding again.It is forbidden to strike arc on the welding base metal.　　

 　　13.In case of snowy weather or wind speed above 6m / s, protective shed shall be set up when steel structure is installed on site. 　　

 　　14.The unqualified weld shall be removed and re welded, and welding shall be carried out according to the regulations of steel structure welding process under negative temperature.

 3、 What problems should be paid attention to in winter steel structure construction?

 　　1.When the ambient temperature is lower than 0 ℃, the coating process test shall be carried out before the anti-corrosion coating is applied. The rust, oil stain, burr, etc. on the surface of the component must be cleaned and the surface shall be dry.Painting shall not be carried out in snowy days or when there is thin ice on the components. 　　

 　　2.During transportation and stacking of steel structures in winter, anti-skid measures shall be taken, and the stacking site of components shall be smooth and solid without water pit and ice on the ground.When the components of the same type are stacked, the components shall be kept horizontal, and the pad iron shall be placed on the same vertical line to prevent the components from slipping. 　　

 　　3.Before installation, the quality of steel structure shall be rechecked according to the requirements under negative temperature conditions. The components that are not inspected during fabrication and deformed during transportation and stacking shall be repaired and corrected on the ground.　　

 　　4.The installation sequence chart of steel members is prepared according to the temperature conditions, and the installation is carried out in strict accordance with the specified sequence during construction. 　　

 　　5.The installation sequence chart of steel members is prepared according to the temperature conditions, and the installation is carried out in strict accordance with the specified sequence during construction. 

　　6.The installation and welding process of steel structure shall be prepared, and both ends of a component shall not be welded at the same time.　　

 　　7.Before installation, the ice, snow and dew on the surface of components shall be removed, but the coating shall not be damaged.　　

 　　8.The columns and main beams installed at negative temperature shall be corrected immediately, and their positions shall be corrected correctly and fixed permanently immediately. The components installed on the same day shall form a stable space system. 　　

 　　9.During the installation of high strength bolt joint, there shall be no snow and ice on the friction surface of the components, and no dirt, oil, etc. shall be contacted. 　　

 　　10.The installation quality of steel structure under negative temperature shall not only comply with the requirements of code for construction and acceptance of steel structure engineering, but also be inspected and accepted according to the design requirements.