System and method for a gliding tuned mass damper

Abstract

A tuned mass damper (TMD) is provided for damping movement of a structure. The TMD includes a mass with a bottom surface having a center point, a first pair of opposed inclined planar surfaces extending away from the center point, and a second pair of opposed inclined planar surfaces extending away from the center point and interposed between the first pair of planar surfaces. The TMD also includes a mass support assembly facing the bottom surface and movably supporting the mass. The mass support assembly includes low friction interfaces that provide at least four points of support to the mass, each point of support communicating with a respective planar surface for providing omnidirectional motion of the mass. A method is also provided for damping movement of a structure, including providing a mass movably supported on a mass support assembly and having omnidirectional movement over the mass support assembly.

Description

SYSTEM AND METHOD FOR A GLIDING TUNED MASS DAMPERFIELD

[0001] The present disclosure relates to a damper and more specifically to a tuned mass damper.BACKGROUND

[0002] A tall structure such as a multi-story building has unwanted movement due to external factors such as wind. To dampen such movement, a tuned mass damper (TMD) is positioned at or near the upper end of the structure.

[0003] A TMD includes a mass that moves in response to movements of the structure in which it is positioned. The TMD may be able to move in two axes that are substantially aligned with the long and short dimensions across the top plan view of the structure. The TMD is "tuned", i.e., it is constructed so that movement of the mass has first-order frequencies across each axis that are predetermined relative to the corresponding natural frequencies of the respective vibration modes of the structure.SUMMARY

[0004] In the present disclosure, a system and method for a tuned mass damper are provided. An object of the present disclosure is to provide a TMD that has a small vertical size, low static and kinetic friction and that operates with independently tunable orthogonal frequencies.

[0005] Thus, by one broad aspect of the present invention, a TMD is provided for damping movement of a structure. The TMD includes a mass with a bottom surface and a mass support assembly facing the bottom surface and movably supporting the mass. The bottom surface of the mass includes a center point, a first pair of opposed inclined planar surfaces extending away from the center point, and a second pair of opposed inclined planar surfaces extending away from the center point and interposed between the first pair of planar surfaces. The mass support assembly includes low friction interfaces that provide at least four points of support to the mass, each point of support communicating with a respective planar surface for providing omnidirectional motion of the mass.

[0006] By a further aspect of the present invention, a method is provided for damping movement of a structure. The method includes providing a mass movably supported on a mass support assembly and having omnidirectional movement over the mass support assembly. The mass has a bottom surface facing the mass support assembly. The bottom surface includes a center point, a first pair of opposed inclined planar surfaces, extending away from the center point, and a second pair of opposed inclined planar surfaces extending away from the center point and interposed between the first pair of planar surfaces. The mass support assembly includes low friction interfaces that provide at least four points of support, each point of support communicating with a respective planar surface, for providing omnidirectional motion of the mass.

[0007] A further understanding of the functional and advantageous aspects of the invention can be realized by reference to the following detailed description and drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments disclosed herein will be more fully understood from the following detailed description taken in connection with the accompanying drawings, which form a part of this application, and in which:

[0009] FIG. 1 is a top perspective view of a TMD on a structure according to an embodiment of the present disclosure.

[0010] FIG. 2 is bottom perspective view of the TMD shown in FIG. 1.

[0011] FIG. 3A is a side plane view of a mass of the TMD shown in FIG. 2.

[0012] FIG. 3B is a front plane view of the mass shown in FIG. 2 and FIG. 3A.

[0013] FIG.4 is a side view of the TMD shown in FIG. 1, illustrating the TMD displaced in one axis.

[0014] FIG. 5 is a bottom perspective view of the TMD shown in FIG. 1, illustrating the TMD displaced in both horizontal axes simultaneously.DETAILED DESCRIPTION

[0015] The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.

[0016] Although the invention has been described with a preferred embodiment, it should be noted that the inventor can make various modifications, additions, and alterations to the invention without departing from the original scope as described in the present disclosure.

[0017] A tuned mass damper (TMD) is used to dampen movement of a structure, such as a tall building, that has unwanted movement due to wind or other external factors. The TMD generally will include a movable mass. The TMD functions to dampen the structure movement by providing a motion of the mass that is resonant with the structure movement. The motion of the mass may be unidirectional with respect to either a longer / length plan dimension or a shorter / width plan dimension of the structure, or it may be bidirectional, providing damping in both the directions, i.e. the longer / length plan dimension and the shorter / width plan dimension of the structure.

[0018] One issue with TMDs in high-rise buildings is that they are of large size due to their necessary mass. A second issue is that the weight of the TMD must be supported by a means with very low friction such that the mass can oscillate freely in one or more lateral directions at low building accelerations, on the order of one or two thousandths of gravity. A third issue is concerned with the mechanism(s) that are used to cause a restoring force when the TMD is moved away from its central resting position, such force to be linearly proportional to the displacement in a given direction so as to create a "natural" resonant frequency in that same direction, but which is not necessarily desired to be the same frequency in the perpendicular direction. Existing solutions to one or more of these issues generally impose undesirable constraints on the other issues and / or come with their own drawbacks.

[0019] A system and method for a TMD is disclosed herein that overcomes these limitations. The object of the present disclosure is to provide a TMD that has a small vertical size such that it fits within a single building story, a low static and kinetic friction, and that operates with independently tunable orthogonal frequencies.

[0020] In the following description, the terms "substantially" and "approximately" mean within a deviation of 10%; "ground plane" means a horizontal plane;"omnidirectional" means more than one direction with respect to the ground plane (but not in the vertical direction); and "low friction" means freely moving with negligible resistance due to friction.

[0021] Referring to FIG. 1 and 2, a TMD 100 for damping movement of a structure is provided. The TMD 100 includes a mass 104 movably supported by a mass support assembly 106. The mass 104 is able to move over the mass support assembly 106 with negligible friction. The mass 104 has a natural central resting position when not in motion. The mass 104 has a bottom surface 108 facing the mass support assembly 106, and a center point 110 of the bottom surface 108. The center point 110 of the bottom surface 108 may be a solid feature of the bottom surface 108 or it may be a space that coincides with an approximately central point of the bottom surface 108.

[0022] Referring to FIG. 2, 3A and B, the bottom surface 108 of the mass 104 includes a first and a second pair of opposed inclined planar surfaces 114, 116. Each planar surface extends away from the center point 110 of the bottom surface. The second pair of planar surfaces 116 is interposed between the first pair 114, so that the bottom surface 108 has alternating planar surfaces of the first pair 114 and the second pair 116.

[0023] The mass support assembly 106 includes at least four points of support for the mass 104, through the low friction interfaces 118, 119. Each of the low friction interfaces 118, 119 communicates with one of the planar surfaces of the first and second pairs 114, 116. The arrangement of the points of support 118, 119 against the inclined planar surfaces 114, 116 allows omnidirectional motion of the mass 104. The first pair of planar surfaces 114 produces a first axis of motion 115 perpendicular to a second axis of motion 117 produced by the second pair of planar surfaces 116.

[0024] Referring to FIG. 3A, the first pair of opposed planar surfaces 114 includes a first planar surface 120 and a second planar surface 122. The first planar surface 120 has afirst angle of inclination 124 relative to the plane normal to the vertical axis of the mass 112 and the second planar surface 122 has a second angle of inclination 126 relative to the plane normal to the vertical axis of the mass 112. The first angle of inclination 124 is approximately equal to the second angle of inclination 126.

[0025] Likewise, referring to FIG. 3A, the second pair of opposed planar surfaces 116 includes a third planar surface 128 and a fourth planar surface 130. The third planar surface 128 has a third angle of inclination 132 relative to the plane normal to the vertical axis of the mass 112 and the fourth planar surface 130 has a fourth angle of inclination 134 relative to the plane normal to the vertical axis of the mass 112. The third angle of inclination 132 is approximately equal to the fourth angle of inclination 134.

[0026] The first and second angle of inclination 124, 126 and the span between their associated low friction interfaces 118 create a natural frequency of oscillation of the mass in a first direction of the structure in the ground plane. Likewise, the third and fourth angle of inclination 132, 134 and the span between their associated low friction interfaces 119 create a similar or dissimilar natural frequency in a second direction perpendicular to the first also within the ground plane. With the mass having a natural frequency of oscillation in both the first and second directions, the motion of the mass 104 in response to movement of the structure is near the resonance frequencies of the structure. Additional damping means (not shown) dissipate energy to thereby damp the movement of the structure.

[0027] Referring to FIG.4 and 5, the points of support provided by the low friction interfacesll8,119 making up part of the mass support assembly 106 may be articulated so they remain oriented and in smooth continuous contact to the planar surfaces 120, 122, 128, 130 as the mass 104 moves and thereby continuously support the planar surfaces in their perpendicular orientations.

[0028] The low friction interface assemblies 118, 119 may utilize a fluid interface. In non-limiting examples, the fluid interface may be an oil-, water- or air-supported interface.

[0029] The TMD 100 may include a sensor 136 for sensing movement of the structure. The sensor 136 and a driven actuator may be used to adjust the low friction interface when movement of the structure is over a minimum threshold. For example, the fluid-support of the low friction interface may be adjusted when movement of the structure is over a minimum threshold value, switching the interface from a default high friction state, in which the TMD is immobilized, to a low friction state to permit motion of the mass when movement of the structure is over the minimum threshold value.

[0030] The same or a different sensor 136 and actuator may be included for sensing movement of the structure and adjusting the low friction interface 118, 119 when movement of the structure exceeds a maximum threshold value or when the structure passes back into a period of low building acceleration / movement, thereby disabling the low friction state and transitioning to a high friction state to essentially immobilize the TMD.

[0031] In a further embodiment, the system 100 may include an anti-yaw mechanism for restricting rotation around the vertical axis of the mass 112. In a nonlimiting example, rods and linkages (not shown) may be connected between the mass 104 and structure 102 to prevent a rotating yaw-axis motion of the mass 104 while still allowing a slight rotation about pitch and / or roll axes of the mass.

[0032] A method for damping movement of a structure with a TMD 100 is also provided. According to the method, a mass 104 is supported on a mass support assembly 106 and able to move omnidirectionally over low friction interfaces 118, 119. Motion of the mass 104 is tuned to damp movement of the structure. The mass 104 has a central resting position when not in motion.

[0033] The mass 104 has a bottom surface 108 facing the mass support assembly 106. The bottom surface 108 has a center point 110 and a first and second pair of opposing inclined planar surfaces 114, 116 extending away from the center point. The second pair of planar surfaces 116 is interposed between the first pair 114. The first and second pair of planar surfaces provide a range of motion for the mass 104 over the mass support assembly 106.

[0034] The first pair of opposed planar surfaces 114 includes a first planar surface 120 and a second opposing planar surface 122. The first planar surface 120 has a first angle of inclination 124 relative to the plane normal to the vertical axis of the mass 112 and the second planar surface 122 has a second angle of inclination 126 relative to the plane normal to the vertical axis of the mass 112. The first angle of inclination 124 is approximately equal to the second angle of inclination 126.

[0035] Likewise, the second pair of opposed planar surfaces 116 includes a third planar surface 128 and a fourth planar surface 130. The third planar surface 128 has a third angle of inclination 132 relative to the plane normal to the vertical axis of the mass 112 and the fourth planar surface 130 has a fourth angle of inclination 134 relative to the plane normal to the vertical axis of the mass 112. The third angle of inclination 132 is approximately equal to the fourth angle of inclination 134.

[0036] Thus, each of the inclined planar surfaces 120, 122, 128, 130 has an angle of inclination 124, 126, 132, 134 relative to the plane normal to the vertical axis 112 of the mass 104. The TMD 100 is tuned by setting the angles of inclination 124, 126, 132, 134 for each pair of planar surfaces 114, 116 and by the span between their associated low friction interfaces 118, 119 to create a natural frequency of movement of the mass in tune with a natural frequency of lateral vibration of the structure.

[0037] The first and second angle of inclination 124, 126 and span between their associated low friction interfaces 118 are initially determined nominally, and can be finetuned later, to create a natural frequency of oscillation of the mass in a first direction of the structure in a ground plane. Likewise, the third and fourth angle of inclination 132, 134 and span between their associated low friction interfaces 119 are determined nominally, and can also be separately fine-tuned later, to create a similar or dissimilar natural frequency in a second direction of the structure perpendicular to the first, also within the ground plane. With the mass having a natural frequency of oscillation in both the first and second directions, the motion of the mass 104 in response to movement of the structure is near the resonance frequencies of the structure. For example, the first / second angle of inclination 124, 126 and the span between their associated low friction interfaces 118 may be tuned to a vibration mode oriented with a longer / length plan dimension of a tall building and the third / fourth angle of inclination 132, 134 and span between their associated low fiction interfaces 119 may be tuned to a second mode of vibration mostly oriented in a shorter / width plan dimension of the tall building. Additional damping means (not shown) dissipate energy to damp the movement of the structure.

[0038] The mass support assembly 106 includes low friction interfaces 118, 119 with at least four points of support, each point of support communicating with a respective planar surface 120, 122, 128, 130, thereby providing omnidirectional motion of the mass 104 to dampen movement of the structure. The points of support of the low friction interfaces 118, 119 may articulate so that, as the mass 104 moves, the points of support maintain a perpendicular orientation with the respective planar surface 114, 116.

[0039] The low friction interfaces 118, 119 may be a fluid interface. In a non-limiting example, the fluid interface may be an oil, water, or air interface. A pressure of the fluid is provided at the low friction interface 118, 119, against the planar surfaces 120, 122, 128,130 thereby supporting the mass 104 above the points of support of the low friction interfaces 118, 119 to allow a low friction movement of the mass over the mass support assembly 106. The motion of the mass 104 over the mass support assembly 106 has a range of motion, or amplitude, defined by the planar surfaces 120, 122, 128, 130. The omnidirectional motion of the mass 104 may occur in one or a combination of the axis of the length of the structure and the axis of the width of the structure.

[0040] The low friction interfaces 118, 119 support of the mass 104 may be adjusted when movement of the structure is over a minimum threshold, thereby allowing damping when the structure movement is above a pre-determined value. For example, the fluidsupport of the low friction interface may be adjusted when movement of the structure is over a minimum threshold value, switching the interface from a default high friction state, in which the TMD is immobilized, to a low friction state to permit motion of the mass when movement of the structure is over the minimum threshold value. As a non-limiting example, adjusting the low friction interface may correspond to providing a high-pressure air flow through the low friction interfaces 118, 119. The low friction interfaces 118, 119 may likewise be adjusted when movement of the structure is over a maximum threshold or returns below the minimum threshold, returning the low friction interface to a default high friction state and immobilizing the mass 104.

[0041] An anti-yaw mechanism connected back to the structure 102 may be included to prevent a rotational yawing motion of the mass 104 about its vertical axis and restrict the motion of the mass to mainly translation motion in the horizontal plane.

[0042] The present invention has been shown and described in a preferred embodiment. It is recognized, however, that departures may be made within the scope of the invention and that obvious modifications will occur to a person skilled in the art. With respect to the above description, it is to be realized that the optimum dimensionalrelationships for the parts of the presented invention, to include variations in size, materials, shape, form, function, and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specifications are intended to be encompassed by the present invention.

Claims

WHAT IS CLAIMED IS:

1. A tuned mass damper (TMD) for damping a movement of a structure, the TMD comprising:a mass, having a bottom surface; anda mass support assembly facing the bottom surface and movably supporting the mass;wherein the bottom surface of the mass comprises:a center point;a first pair of opposed inclined planar surfaces, extending away from the center point; anda second pair of opposed inclined planar surfaces extending away from the center point and interposed between the first pair of planar surfaces; andwherein the mass support assembly comprises low friction interfaces providing at least four points of support, each point of support communicating with a respective planar surface, for providing omnidirectional motion of the mass.

2. The system of claim 1, whereinthe first pair of opposed planar surfaces comprises:a first planar surface having a first angle of inclination relative to a plane normal to a vertical axis of the mass and a second planar surface opposing the first planar surface and having a second angle of inclination relative to the plane normal to the vertical axis of the mass substantially equal to the first angle of inclination; andthe second pair of opposed planar surfaces comprises:a third inclined planar surface having a third angle of inclination relative to the plane normal to the vertical axis of the mass and a fourth inclined planar surface opposing the third planar surface and having a fourth angle of inclination relative to the plane normal to the vertical axis of the mass substantially equal to the third angle of inclination.

3. The system of claim 2, wherein the first and second angle of inclination and a first span between the associated points of support are tuned according to a first natural frequency of lateral vibration of the structure and the third and fourth angle of inclination and a second span between their associated points of support are tuned according to a second natural frequency of lateral vibration of the structure.

4. The system of claim 1, wherein each point of support articulates to maintain a perpendicular communication with the respective planar surface.

5. The system of claim 1, wherein each point of support comprises a swivel ball or a castor to maintain perpendicular contact with the respective planar surface.

6. The system of claim 1, wherein the low friction interface comprises a fluid- supported interface.

7. The system of claim 6, wherein the fluid comprises at least one of oil, water and air.

8. The system of claim 1, further comprising a sensor connected to the structure, for adjusting the low friction interface when movement of the structure is over a minimum threshold.

9. The system of claim 1, further comprising a sensor connected to at least one of the structure or the mass for adjusting the low friction interface when movement of the structure is at least one of over a maximum threshold or under the minimum threshold.

10. The system of claim 1, further including an anti-yaw mechanism for restricting a twisting motion of the mass.

11. A method for damping movement of a structure, the method comprising:providing a mass movably supported on a mass support assembly and having omnidirectional movement over the mass support assembly, the mass having a bottom surface facing the mass support assembly, wherein the bottom surface comprises:a center point;a first pair of opposed inclined planar surfaces, extending away from the center point; anda second pair of opposed inclined planar surfaces extending away from the center point and interposed between the first pair of planar surfaces; andwherein the mass support assembly comprises a low friction interface including at least four points of support, each point of support communicating with a respective planar surface, for providing omnidirectional motion of the mass.

12. The method of claim 11, whereinthe first pair of opposed planar surfaces comprises:a first planar surface having a first angle of inclination relative to a plane normal to a vertical axis of the mass and a second planar surface opposing the first planar surface and having a second angle of inclination relative to the plane normal to the vertical axis of the mass substantially equal to the first angle of inclination; and the second pair of opposed planar surfaces comprises:a third inclined planar surface having a third angle of inclination relative to the plane normal to the vertical axis of the mass and a fourth inclined planar surface opposing the third planar surface and having a fourth angle of inclination relative to the plane normal to the vertical axis of the mass substantially equal to the third angle of inclination.

13. The method of claim 12, wherein the first and second angles of inclination and a first span between the associated points of support are tuned to a first natural frequency of lateral vibration of the structure and the third and fourth angle of inclination and a second span between their associated points of support are tuned according to a second natural frequency of lateral vibration of the structure.

14. The method of claim 11, wherein each point of support articulates to maintain a perpendicular communication with the respective planar surface.

15. The method of claim 11, wherein each point of support comprises a swivel ball or a castor to maintain perpendicular contact with the respective planar surface.

16. The method of claim 11, wherein the mass has a range of motion for damping movement of the structure provided by the planar surfaces.

17. The method of claim 11, wherein the low friction interface adjusts from a high friction state to a low friction state when movement of the structure exceeds a minimum threshold.

18. The method of claim 11, wherein the low friction interface adjusts from a low friction state to a high friction state when movement of the structure is at least one of over a maximum threshold or under the minimum threshold.

19. The method of claim 11, wherein the mass is prevented from a twisting motion about a mostly vertical axis by an anti-yaw mechanism.

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