Pendulum mass damper
A pendulum mass damper is directed to damping oscillation of tall buildings, towers or similar flexible structures requiring a low frequency tuned mass damper (TMD) for reducing a e.g. wind or earthquake induced displacement response of the structure. A mass ( 1 ) is balanced by a first spring system ( 2 a, 2 b, 2 c ) and supported by a carrying part ( 4 ) to maintain a vertical position, the carrying part ( 4 ) carrying the mass in the vertical direction extends between the mass and a position (C) below the mass, i.e. the weight of the mass is carried or supported from or at a point or level below the mass, wherein the mass at the position (C) below the mass is fixed and/or connected to a unit ( 5 ) constituting a base of a supporting system for the mass which unit is floating i.e. the unit can move either horizontally or both horizontally and vertically.
1. A pendulum mass damper for damping oscillations of a structure, the pendulum mass damper comprising a mass ( 1 ) balanced by a first spring system ( 2 a , 2 b , 2 c ) that balances the mass ( 1 ) horizontally and is positioned above or at substantially a same vertical level as the mass ( 1 ), wherein the mass is supported by a carrying part ( 4 ) to maintain a vertical position, the carrying part ( 4 ) carrying the mass ( 1 ) in the vertical direction extends between the mass ( 1 ) and a position (C) below the mass ( 1 ), and therefore the weight of the mass ( 1 ) is carried or supported from or at a point or level below the mass ( 1 ), such that the mass ( 1 ) at the position (C) below the mass is connected to a unit ( 5 ) constituting a base of a supporting system for the mass ( 1 ), the unit ( 5 ) balanced by flexible parts ( 8 ) such that the unit ( 5 ) can move either horizontally or both horizontally and vertically.
2. The pendulum mass damper according to claim 1 , wherein the unit ( 5 ) is constituted of a floating part.
3. The pendulum mass damper according to claim 1 , wherein the carrying part ( 4 ) comprises a central carrying part ( 4 ) extending from a suspension frame ( 7 ) to the position (C).
4. The pendulum mass damper according to claim 1 , wherein the first spring system ( 2 a , 2 b , 2 c ) balances the mass ( 1 ) horizontally and is attached at the central axis above the vertical level of the mass ( 1 ) within a distance of the top of the mass being less than 20%, or being less than 10% or being less than 5%, from the total length of the pendulum measured from a central point (C) to the fastening points or fastening level (F) of the springs.
5. The pendulum mass damper according to claim 1 , wherein the first spring system ( 2 a , 2 b , 2 c ) comprises at least three springs or at least balances the mass in three directions.
6. The pendulum mass damper according to claim 1 , the carrying part ( 4 ) comprises a central carrying part ( 4 ) in form of one or more cables or similar extending from a suspension frame ( 7 ) to the position (C).
7. The pendulum mass damper according to claim 1 , wherein the carrying part ( 4 ) also comprises support parts ( 3 ) extending from the mass ( 1 ) to the unit ( 5 ) positioned below the mass ( 1 ).
8. The pendulum mass damper according to claim 1 , wherein the unit ( 5 ) comprises a joint allowing either the support part(s) ( 3 ) or the carrying part(s) ( 4 ) to pivot relative to the unit ( 5 ).
9. The pendulum mass damper according to claim 8 , wherein the joint has one, two or three degrees of freedom i.e. the joint may allow the mass ( 1 ) to pivot relative to the unit ( 5 ) in one, two or more than two directions.
10. A structure comprising the pendulum mass damper according to claim 1 .
11. The structure according to claim 10 , wherein the structure is a building, wind turbine tower, or chimney.
12. The pendulum mass damper according to claim 1 , wherein said flexible parts ( 8 ) comprise a second spring system.
13. The pendulum mass damper according to claim 12 , wherein the second spring system ( 8 ) comprises at least three springs.
14. The pendulum mass damper according to claim 1 , wherein the pendulum mass damper comprises one mass ( 1 ) balanced by the first spring system ( 2 a , 2 b , 2 c ).