Increasing the airspeed on a fixed-wing aircraft allows to reach higher load factors, sometimes beyond the structural strength. This is why some fixed-wing aircrafts have g-limitations.
There is nothing similar on a helicopter. Beyond 100 Kts the load factor capability only decreases. The load factor you are able to reach in 100 Kts conditions cannot be exceeded in the whole flight envelope. The structural strength substantiation takes it in account.