Do large-span steel structure space frame need to be fireproof
The long-span steel structure space frame usually loses its bearing capacity at a temperature of 450-650 °C, and undergoes great deformation, resulting in the bending of steel columns and steel beams, and cannot be used continuously due to excessive deformation. Generally, the fire resistance limit of unprotected steel structures is about 15 minutes. The length of this time is also related to the rate at which the component absorbs heat. In order to make steel structure materials overcome the deficiencies of fire protection in practical applications, fire protection treatment must be carried out. The purpose is to increase the fire resistance limit of the steel structure to the limit range specified in the design code. There are various measures to prevent the steel structure from deforming and collapsing due to rapid heating in a fire. The key is to take different methods according to different situations, such as using heat insulation and refractory materials to block the flame to directly burn the steel structure, reducing the speed of heat transfer and delaying the time for the temperature rise and strength weakening of the steel structure. But no matter what method is adopted, the principle is the same.
Whether the steel structure space frame should be sprayed with fire retardant coating should be determined according to the fire hazard category. "Code for Fire Protection Design of Buildings" clearly stipulates that Class D and E can not be sprayed, and Class C and above must be sprayed. Steel as a building material has some unavoidable defects in fire prevention. Its mechanical properties, such as yield point, tensile strength and elastic modulus, will drop sharply with the increase of temperature. Therefore, it is very necessary to do fire protection of steel structure space frame.
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