Openings in sidewalks provided for in Section 24.65.010 must be supplied with doors attached to a frame built into the sidewalk and must be capable of supporting a uniform live load of 250 pounds per square foot and a concentrated live load of 8,000 pounds. The live loads do not need to be applied concurrently. The door must be constructed of sheet steel or other approved metal that has an approved non-slip surface. The dimensions of the door in any direction may not exceed the dimension of the opening by more than 6 inches. The doors and frames must be so constructed and maintained that there is no projection above or below the sidewalk exceeding 1/4 inch and existing doors that do not conform to the requirements must be changed to conform within a period of 10 days after notice is given to change the same. Sidewalk doors must be provided with a metal guard that, when the doors are open, will hold the doors open. This guard must be located on the side of the sidewalk opening nearest the property line. The guard must be made in the form of a grating with openings not exceeding 6 inches in dimension and so arranged that a child cannot get under or through the guard. This guard is not required for doors having metal gratings that are level with the sidewalk when the doors are open and the elevator platform is below the sidewalk level. Such gratings must be capable of supporting a uniform live load of 250 pounds per square foot and a concentrated live load of 8,000 pounds. The live loads do not need to be applied concurrently. Elevators having these sidewalk gratings must be provided with a 3/4-inch steel bar to hold the doors open.