North,
I've had to do this and I believe they consider them intermittent.
It is regulated by ANSI 17.1.
Like any submittal, you have to ask the elevator contractor for his load ratings and include them in your own as an appliance.
If the contractor has not been selected yet, you can usually find one who will quote you load data. How tall, etc. is all they require. If the bldg is short enough you may have to 'guess' if they want to go hydraulic and you may find you'll have to adjust your calc after the elevator contractor is selected.
Most property owners use the same elevator company over and over.
Back to your question, the definition of intermittent is expected to last for 5 minutes or less, and most elevators never run for a continuous 5 minute period without stopping at a floor.
They design the equipment for continuous use however.
