For the record if anyone is reading this, Australia and New Zealand has a bunk bed safety standard. In the standard there are various safety requirement, there is static load requirement and dynamic impact load requirement on the ladder, unfortunately you have to buy the standards to get a soft copy, it cost about $120 USD after tax.
Without going into too much detail,
For static load requirement you are to test the ladder by putting an object of 1500N at 100mm interval of the tread for 30 seconds at each interval
For dynamic load, your ladder should be subjected to an impact load of 15kg, located at 400m from the tread and impact the tread at 150mm distance for 10 impacts, the 15kg object is tied to a rod that is 1000mm from the centre of its pivot point. the tread is 1400mm from the pivot point.
If you require further info about relevant safety requirement in this safety standard, send me a PM.