Because of its high strength, excellent plasticity and bending, and small overall weight and short construction period, steel stairs are favored by developers and owners.One of the common steel structure stairs is the outdoor fire stairs, so how obvious are the advantages of building steel structure fire stairs?

    1.Allowable time for safe evacuation

    The allowable time for safe evacuation refers to the time when people leave the building on fire and arrive at the safe area.The allowable time of safe evacuation is an important basis to determine the distance of safe evacuation, the width of safe passage and the number of emergency exits.If the building is a smoke proof staircase, the evacuation time on the staircase will not be calculated.

     The allowable time for safe evacuation can be 5-7 minutes for high-rise buildings; for general civil buildings, the fire resistance rating of grade I and II should be 6 minutes, and that of grade III and IV can be 2-4 minutes; for densely populated public buildings, the fire resistance rating of grade I and II shall be 5 minutes, and that of buildings with grade III fire resistance shall not exceed 3 minutes, and the time for evacuation from the auditorium shall be grade I and II.The fire resistance rating of grade III buildings shall not exceed 1.5 minutes.

    2.Safe evacuation distance

    The safe evacuation distance of civil buildings refers to the maximum distance from the door of the room or residential house to the nearest external exit or staircase; the safe evacuation distance of the workshop refers to the maximum distance from the farthest working point in the plant to the external exit or staircase.The purpose of limiting the safe evacuation distance is to shorten the evacuation time and make people evacuate from the fire scene to the safe area as soon as possible.