[maxerickson]

First, I'm not doing structural design, so maybe someone will wander by with a better answer. Anyway, it's probably overly simplistic, but passing the load test would involve surviving the maximum expected load with zero damage. Implying that lesser loads would also never do damage.

In reality, cyclic fatigue is also considered.

This seems like a nice discussion that shows the complexity:

http://www.coe.montana.edu/me/faculty/cairns/Introduction%20...