The steel structure usually loses its bearing capacity in the temperature of 450 ℃ - 650 ℃, and great deformation occurs, which leads to the bending of steel column and steel beam. As a result, the steel structure cannot continue to be used due to excessive deformation. Generally, the fire resistance limit of unprotected steel structure is about 15 minutes. The length of this time is also related to the heat absorption rate of the component.
Use the method of double crane to lift the steel pile. When the double crane lifts the steel column horizontally, stop when it reaches the appropriate height; push the transport flat car away, open the rotary brake with the double crane, and then use the main crane to lift it alone; when the steel column is lifted back straight, remove the auxiliary crane, and then use the main engine to lift it alone. When checking the steel column, adjust the vertical deviation to less than 20 mm, and then use a theodolite to check the verticality; use a 10 mm thick steel mold to locate near the column, and fix it with electric welding and anchor bolts to avoid deviation.
Seismic resistance: the roofs of low-rise villas are mostly sloped roofs, so the roof structure basically adopts a triangular roof truss system made of cold-formed steel members. After sealing structural plates and gypsum boards, the steel structure forms a very solid "plate rib structure system", which has stronger seismic resistance and horizontal load resistance ability, and is suitable for seismic intensity of 8 degrees The above areas.