The hydraulic power units on aircraft like 747's are designed to dampen movement (to a degree), but they will still move to their limits/stops. I see this all the time on the 747 and similar aircraft (today, in fact... and it wasn't all that windy). On the larger Boeings however, there is no mechanical feedback to the stick (no danger to the pilots). On windy days, you are more at risk from motion sickness
I recall reading somewhere (perhaps the Boeing Maintenance Manual) that hydraulics are to be applied if hurricane force winds are expected (where the aircraft cannot be flown to safety).
Regards.
Q.