free ends 12a and 12b of clamp 12 respectively in the event of an earthquake shock or vibration due to wind hydraulic jack 14 is energized to expand the clamp 12 until the rod 9 is freely movable should vibrator 2 become inoperative the pressure to the hydraulic jack 14 is stopped and clamp 12 is biased by the action of springs 13 into engagement with the groove 11 of the detent 10 to immobilize rod 9 fig7 to 9 show another embodiment of a fixing device 3a in which a rod 15 is provided with a plurality of brake plate members 16 which are selectively grippable by brake means 17 the brake means 17 are normally spring biased into gripping engagement with brake plate members 16 and disengaged by an electric solenoid or hydraulic jack means not shown to release rod 15 for free movement in the event of an earthquake fig1 shows a multistage pendulum type combination seismic response and wind control system as another applied embodiment a weight 21 is suspended from a support frame 26 by the use of suspending members 24 25 and suspension means divider 26a to provide a pendulum a fixing device 23 is mounted on the support frame 26 and positioned to act against suspending member suspension means divider 26a fixing device 23 and suspension means divider 26a coact to function as a pendulum frequency modifier when the combination seismic response and wind control system is.