How long is the fire resistance rating of steel structure two?
According to the provisions of the "design of tall buildings" fire, fire is the highest grade, the time required for refractory component, column: 3 hours, beam: 2 hours, 1.5 hours; the fire floor: grade two, time requirements for the refractory component column: 2.5 hours, 1.5 hours, beam: floor: 1 hours. For fire retardant coating, the fireproof time of ordinary thin fireproof coating shall not exceed 1.5 hours, and thicker fireproof coating should be adopted for more than 1.5 hours.
Fireproof steel can be used (or concrete masonry brick, fireproof coating method), fireproof coating and composite structure of several methods of fire prevention board can be divided into fire plate and sheet thickness, the thickness of fireproof plate thickness is 20 ~ 50MM, the main fire board of calcium silicate and stone fire expansion borers in main varieties KB board, CF board; fireproof sheet thickness between 6 ~ 15MM, the main varieties of inorganic plate reinforced short fiber reinforced cement pressure plate, the ordinary fiber reinforced calcium silicate plate and glass cloth.
Therefore, when the fire resistance rating of steel structure is two, the refractory time requirement of the component is as follows: column: 2.5 hours, beam: 1.5 hours, floor: 1 hours. The steel structure can be made up of wrapped concrete (or masonry bricks), fireproof coating, fireproof board cladding and composite structure, and the required refractory time can be achieved.
As everyone knows, the steel structure is usually at 450 DEG C to 650 DEG C temperature will lose the bearing capacity, big deformation, resulting in steel column and beam bending, the results caused by excessive deformation can't continue to use, generally without steel structure fireproof limit protection for 15 minutes.
