When ALT* or ALT is engaged and ATHR is blue(armed) then there is no protection but if thrust is active (white) FMGS will limit the speed to VMAX. Also in SRS if thrust levers are left in TOGA at acceleration altitude FMGS will limit the speed to VMAX by increasing climb. Momentary over speed warning while retracting flaps to zero at high weights does not cause any structural problems.