Helicopter pad?

Has anyone had any experience designing a helicopter pad? Specifically around impact loads?

 

I would be AMAZED if there were no published specs for this - consider looking at ABS/Lloyds/DNV etc. for offshore oil rigs, etc.
Steve

 

RDB “Boat international” magazine for march 2006 has an article on helicopters and pads, its not a tech article but it does have weights and rotor radii’s of a lot of helicopters.

 

RDB, I think our own navy has perhaps the world's most thorough experience with impact loads on helicopter pads!
In general, helicopters tend to be pretty light- but when they come down quick, all that weight (and downward momentum) is applied on a very small landing gear area. The biggest thing with a helipad is getting enough clearance around it to safely bring the chopper in; only a very skilled pilot can safely land on a pad where side clearance is less than twice the rotor diameter. Keep big safety factors in the pad structure itself, and build the structures around it strong enough to handle a rotor failure. I'm afraid I don't have any quantitative values for this; Steve's suggestion to look at oil-rig scantlings is probably a good starting point.