Convergence into passageways - three questions

[blugosi]

Scratching my head on this....

Convergence requirements per 1005.6 are clear for a simple staircase. We must add occupants coming up from the basement into the LED to occupants coming down from the first floor to the same vestibule, because the relevant populations shall meet by the final exit at the same time and there will be a bottleneck.
How about the following 3 scenarios though?

1. What if occupants from these two levels arrive into an relatively long (say 400 feet long) exit passageway? Do we still add them? I suppose so.
2. What if occupants entering the passageway from the floor below enter the passageway on one side of that long passageway and occupants from the floor below enter it closer to the exit?
Isn't it reasonable to think that, by the time the occupants from the basement reach the convergence point inside the passageway , the occupants from the story above will have exited already?
3. What happens if the evacuation strategy is phased evacuation, where the upper story does not evacuate simultaneously with the bottom story? Do we still need to apply 1005.6?

 

[Yankee Chronicler]

1. Yes.

2. We still add them. By the logic proposed, in a one story building if a long corridor serves 200 people, the exit door at the end only needs to have a capacity of 100 because by the time people from the far end reach the door, the people closer o the exit door will be gone.

3. Do you have a code citation that would suggest phased evacuation eliminates the requirement to add converging egress occupant loads? I could see this scenario being the basis for a request for modification, but I don't think the code allows it directly.

 

[Blazer]

2. We still add them. By the logic proposed, in a one story building if a long corridor serves 200 people, the exit door at the end only needs to have a capacity of 100 because by the time people from the far end reach the door, the people closer o the exit door will be gone.

I think Yankee Chronicler was trying to say that your logic in item #2 is debunked. Follow the code.





If you size the capacity of the exit passageway for 200 people then the discharge shall be sized the same. The minimum width of exit passageway is 44 inches (IBC '18-1024.2). Since capacity (200*0.2=40") is less than minimum width you must use minimum width (always the greater of the two).