U.S. patent application number 12/747401 was filed with the patent office on 2010-10-28 for tuned mass damper.
This patent application is currently assigned to ALGA S.P.A.. Invention is credited to Agostino Marioni.
Application Number | 20100269424 12/747401 |
Document ID | / |
Family ID | 39671515 |
Filed Date | 2010-10-28 |
United States Patent
Application |
20100269424 |
Kind Code |
A1 |
Marioni; Agostino |
October 28, 2010 |
TUNED MASS DAMPER
Abstract
A tuned mass damper comprises a mass (1) restrained to a
structure (2) through supporting means (3) suitable to allow a
pendulum motion of said mass (1) when said structure (2) is subject
to an external force, as well as damping means suitable for
absorbing a portion of the kinetic energy of the moving mass (1).
The supporting means (3) comprise at least one bearing (3) provided
with a concave cylindrical sliding surface (3a) and the damping
means are made as a coating of a controlled friction material of
said sliding surface (3a).
Inventors: |
Marioni; Agostino; (Milano,
IT) |
Correspondence
Address: |
LUCAS & MERCANTI, LLP
475 PARK AVENUE SOUTH, 15TH FLOOR
NEW YORK
NY
10016
US
|
Assignee: |
ALGA S.P.A.
Milano MI
IT
|
Family ID: |
39671515 |
Appl. No.: |
12/747401 |
Filed: |
December 17, 2007 |
PCT Filed: |
December 17, 2007 |
PCT NO: |
PCT/IT07/00871 |
371 Date: |
June 10, 2010 |
Current U.S.
Class: |
52/167.2 |
Current CPC
Class: |
F16F 7/10 20130101; E04H
9/023 20130101; E04H 9/0215 20200501; F16F 2230/0052 20130101 |
Class at
Publication: |
52/167.2 |
International
Class: |
E04B 1/98 20060101
E04B001/98; E04H 9/02 20060101 E04H009/02 |
Claims
1-14. (canceled)
15. A tuned mass damper comprising at least one mass and supporting
means restraining said mass to a structure and suitable to allow a
pendulum motion thereof when said structure is subject to an
external force, said tuned mass damper further comprising damping
means suitable for absorbing a portion of the kinetic energy of the
mass when in motion, wherein said supporting means comprise at
least one bearing and wherein said bearing is provided with a
concave cylindrical sliding surface.
16. The damper of claim 15, wherein said supporting means comprise
a plurality of bearings having concave cylindrical sliding surfaces
of equal curvature and arranged parallel to each other, and wherein
said mass is provided with a plurality of feet arranged at
positions corresponding to the positions of the bearings.
17. The damper of claim 16, wherein each foot consists of an upper
portion restrained to the mass and of a lower portion that has a
convex cylindrical surface suitable to contact the concave
cylindrical sliding surface of the respective bearing.
18. The damper of claim 17, wherein each foot comprises a
cylindrical or spherical cap joint coupling said upper portion to
said lower portion of each foot and wherein said cylindrical or
spherical cap joint is suitable to allow a relative movement and a
relative rotation between the upper portion and the lower portion
of each foot.
19. The damper of claim 17, wherein the damping means are made as
coatings of controlled friction materials of the concave
cylindrical sliding surfaces of the bearings and of the convex
cylindrical surfaces of the lower portions of the feet.
20. The damper of claim 19, wherein the bearings and the lower
portions of the feet are entirely made of controlled friction
materials.
21. The damper of claim 19, wherein said controlled friction
materials are stainless steel and polymeric materials selected the
group consisting of polyethylene, polyamidic resins and PTFE
modified and/or filled.
22. The damper of claim 20, wherein said controlled friction
materials are stainless steel and polymeric materials selected the
group consisting of polyethylene, polyamidic resins and PTFE
modified and/or filled.
23. The damper of claim 16, wherein the sliding surfaces of the
bearings have curvature radiuses transversally varying with respect
to the direction of motion of the mass, and wherein the damper
further comprises driving means suitable for modifying the contact
points between the mass and said sliding surfaces.
24. The damper of claim 23, wherein the bearings are arranged in
pairs on the structure, the respective sliding surfaces being
parallel to each other and having a curvature radius increasing
outwards when starting from the plane of symmetry of the damper in
which the mass moves, the feet being correspondingly mounted in
pairs and movably on guides fixed to the mass and arranged
transversally to its motion direction, and wherein said driving
means are connected to each pair of feet and are suitable for
modifying their relative distance.
25. The damper of claim 24, wherein said driving means comprises a
worm, said worm being provided at one end with a maneuvering member
suitable to allow the rotation thereof around its axis, the worm
having a first threaded portion inserted in a threaded hole formed
in the upper portion of a first foot of the pair and a second
portion with opposite threading inserted in a threaded hole formed
in the upper portion of a second foot of the pair.
26. The damper of claim 16, wherein the bearings are arranged in a
multilayer structure, each layer comprising at least a base and one
or more bearings as well as a series of feet at positions
corresponding to the positions of the bearings, the direction of
motion for each layer being defined by the orientation of the
sliding surfaces of the one or more bearings arranged thereon.
27. The damper of claim 26, wherein for each layer of said
multilayer structure the sliding surfaces of the bearings have
curvature radiuses transversally varying with respect to the
direction of motion defined by them, and wherein each layer further
comprises driving means suitable for modifying the contact points
between the feet and the sliding surfaces.
28. The damper of claim 26, wherein in the various layers of said
multilayer structure the couplings between the concave cylindrical
sliding surfaces of the bearings and the convex cylindrical
surfaces of the feet are made with different controlled friction
materials.
29. The damper of claim 27, wherein in the various layers of said
multilayer structure the couplings between the concave cylindrical
sliding surfaces of the bearings and the convex cylindrical
surfaces of the feet are made with different controlled friction
materials.
30. The damper of claim 15, wherein the mass is equal to 2-4% of
the total mass of the structure.
31. The damper of claim 18, wherein the damping means are made as
coatings of controlled friction materials of the concave
cylindrical sliding surfaces of the bearings and of the convex
cylindrical surfaces of the lower portions of the feet.
Description
[0001] The present invention relates to a tuned mass damper and
particularly to a tuned mass damper suitable for the application to
civil and building structures (civil structures and buildings) like
skyscrapers, towers and bridges.
[0002] Tuned mass dampers, also know under the acronym TMD, are
devices for damping vibrations used for stabilizing the motion of a
structure subject to an external force, thus preventing the
structure from being damaged or even yielding.
[0003] Such devices are essentially mechanical systems of the
mass-spring-damper type provided with one or more degrees of
freedom and designed to be in resonance with the structure in which
they are installed. Whenever the structure vibrates subject to any
force like, for example, wind or an earthquake, the dampers oppose
the inertia of the mass to the vibration motion, thus generating,
as an effect of the resonance, equal and opposed forces capable of
nullifying the motions of the structure.
[0004] In the field of building and construction, and particularly
in the construction of very tall structures like skyscrapers,
towers and bridges that are very sensitive to wind and seismic
events, tuned mass dampers are made as pendulum structures wherein
the mass is a cement or steel block supported by ropes or arms
restrained to the structure. The mass moves according to the law of
motion of a pendulum, storing and releasing potential energy
similarly to a mass restrained by a spring of a mass-spring-damper
system, while the damping action is accomplished by one or more
damping means, e.g. of a hydraulic type, arranged in the one or
more preset directions of motion.
[0005] Tuned mass dampers of the pendulum type have remarkable
installation problems, due to the size of both the suspended masses
and the related supporting means. For instance, in the case of a
skyscraper the structure of a tuned mass damper may occupy even
some floors of the building in height.
[0006] Moreover, after the installation, a tuned mass damper always
requires a "tuning" step with respect to the real dynamic behavior
of the structure. In fact, a damper is designed on the basis of a
theoretical model of the structure to which it will be applied,
therefore adjustments of the fundamental period are always required
once the structure has been completed. Generally, a tuning step is
rather complicated and expensive since the adjustment of the length
of the ropes or arms supporting the mass requires the use of
equipment like winches or tension rods, which may be removably or
even permanently installed.
[0007] It is therefore an object of the present invention to
provide a tuned mass damper capable of overcoming said
disadvantages. Said object is achieved by means of a tuned mass
damper whose main features are disclosed in the first claim, while
other features are disclosed in the remaining claims.
[0008] The tuned mass damper according to the present invention
comprises at least one mass restrained to supporting means suitable
to allow a pendulum motion thereof when the structure is subject to
an external force. The supporting means comprise at least one
bearing provided with a concave cylindrical sliding surface.
[0009] The main advantage of the tuned mass damper according to the
present invention is that it has a remarkably smaller size with
respect to known dampers, thus allowing an easier installation into
the structure for which it is intended. In fact, choosing mass
supporting means in the form of at least one concave cylindrical
bearing allows to reduce the system size, which substantially
coincides with the mass size only. Consequently, it is possible to
reduce both the manufacturing and installation costs of the
damper.
[0010] Moreover, by coating or making the sliding surfaces of the
bearings with controlled friction materials, it is possible to
accomplish damping means without resorting to traditional external
devices, e.g. of a hydraulic type or the like, installed on the
structure and restrained to the mass, thus further reducing the
manufacturing costs.
[0011] Another advantage offered by the invention is that the
tuning step of the damper is strongly simplified. In fact, the
sliding surfaces of the bearings are provided with variable
curvature radiuses, thus allowing to adjust the fundamental period
by simply varying the contact point between the supporting means
and the mass transversally to its direction of motion.
[0012] Still another advantage offered by the invention is that it
is possible to make a damper provided with more degrees of freedom
by arranging the bearings on a multilayer structure and orienting
the sliding surfaces of the bearings of each layer such as to
define more directions of motion.
[0013] Moreover, the behavior of the damper in the various
directions of motion may be differentiated by choosing different
curvatures of the sliding surfaces and/or using different
controlled friction materials.
[0014] Further advantages and features of the tuned mass damper
according to the present invention will become clear to those
skilled in the art from the following detailed and non-limiting
description of some embodiments thereof with reference to the
attached drawings, wherein:
[0015] FIG. 1 shows a perspective view of a first embodiment of a
tuned mass damper according to the present invention;
[0016] FIG. 2 shows a detail H of FIG. 1;
[0017] FIG. 3 shows a perspective view of a second embodiment of a
tuned mass damper according to the present invention, provided with
means for tuning the fundamental period;
[0018] FIG. 4 shows a detail IV of FIG. 3;
[0019] FIG. 5 shows a cross-section V-V of FIG. 3;
[0020] FIGS. 6 and 7 show a detail VI and a detail VII of FIG. 5,
respectively;
[0021] FIG. 8 shows a perspective view of a third embodiment of a
tuned mass damper according to the present invention, provided with
two degrees of freedom;
[0022] FIG. 9 shows a detail IX of FIG. 8;
[0023] FIG. 10 shows a cross-section X-X of FIG. 8; and
[0024] FIG. 11 shows a detail XI of FIG. 10.
[0025] Referring to FIGS. 1 and 2, the tuned mass damper according
to the present invention comprises in a known way a mass 1
restrained to a structure 2 through supporting means 3 suitable to
allow a pendulum motion of mass 1 when structure 2 is subject to an
external force as, for instance, wind or an earthquake.
[0026] According to the inventive concept which is the basis of the
present invention, the supporting means 3 comprise at least one
bearing provided with a concave cylindrical sliding surface 3a.
Mass 1, made to move upon the action of a force acting on the
structure, moves along the sliding surface 3a of bearing 3,
increasing and decreasing its potential energy according to the law
of motion of a pendulum. The fundamental period of the oscillation
of mass 1, defined by the radius of the sliding surface 3a, is
substantially equal to the fundamental period of structure 2, thus
the damper and structure 2 are resonant.
[0027] In the design of the damper according to the present
invention, mass 1 is so dimensioned as to be equal to 2-4% of the
total mass of the structure to which it is applied.
[0028] Moreover, the size of mass 1 is remarkably larger with
respect to the order of magnitude of the movements that mass 1
makes in order to react against the movements of structure 2.
Therefore, both for encumbrance and stability reasons the
supporting means comprise a plurality of bearings, whose concave
cylindrical sliding surfaces 3a have the same curvature and are
arranged parallel to each other, thus defining one single direction
of motion for mass 1. Correspondingly, mass 1 is provided with a
plurality of feet 4 arranged at positions corresponding to the
positions of bearings 3.
[0029] In the embodiment shown in FIG. 1, for example, the damper
comprises four bearings 3 respectively provided with sliding
surfaces 3a and mass 1 is provided with four feet 4 arranged at
positions corresponding to the positions of bearings 3.
[0030] As shown in the detail of FIG. 2, each foot 4 consists of an
upper portion 4a restrained to mass 1 and of a lower portion 4b
that has a convex cylindrical surface 4c suitable to contact the
sliding surface 3a of the respective bearing 3.
[0031] The upper portion 4a and the lower portion 4b of each foot 4
are movable with respect to each other and coupled by means of a
cylindrical or spherical cap joint allowing a relative rotation
thereof. In this way, mass 1 moves along the sliding surfaces 3a of
bearings 3 without rotating with respect to the plane of structure
2.
[0032] During the motion of mass 1, a certain amount of kinetic
energy is dissipated through friction in the contact between the
concave cylindrical sliding surfaces 3a of bearings 3 and the
convex cylindrical surfaces 4c of feet 4, thus achieving a damping
effect. Therefore, without resorting to external damping devices as
in known applications, the damper according to the present
invention may be provided with damping means in the form of
coatings of controlled friction materials of the concave
cylindrical sliding surfaces 3a of bearings 3 and the convex
cylindrical surfaces 4c of feet 4.
[0033] Alternatively, bearings 3 and the lower portions 4b of feet
4 may be entirely made of controlled friction materials.
[0034] Preferably, the controlled friction materials are combined
with each other so as to minimize the wear. Suitable controlled
friction materials are, for example, stainless steel and polymeric
materials selected among, e.g., polyethylene, polyamidic resins and
PTFE suitably modified and/or filled.
[0035] Referring to FIGS. 3-7, a second embodiment of the damper
according to the invention is now described, wherein in order to
allow the tuning of the damper with respect to a structure 2, the
sliding surfaces 3a of bearings 3 have radiuses of curvature
transversally varying with respect to the direction of motion of
mass 1, and the damper comprises driving means 6 suitable for
modifying the contact points between mass 1 and the sliding
surfaces 3a. By modifying the contact points between the sliding
surface 3a and mass 1, the latter will move following a path having
a different radius, thus allowing to vary the fundamental period
and thereby to tune the damper according to the actual fundamental
period of structure 2. Preferably, the driving means 6 do not act
directly on mass 1, which is very cumbersome and difficult to move,
but on its feet 4 by modifying their relative distance.
[0036] The bearings 3 are arranged in pairs on structure 2 with the
respective sliding surfaces 3a parallel to each other and having a
curvature radius increasing outwards when starting from the plane
of symmetry of the damper in which mass 1 moves. The feet 4 are
correspondingly assembled in pairs and movably on guides 5 fixed to
mass 1 and transversally arranged with respect to its direction of
motion, and are connected to each other through the driving means
6.
[0037] The driving means 6 comprise a worm provided at one end with
a maneuvering member 7, e.g. a lever, suitable to allow the
rotation thereof around its axis. The worm 6 comprises a first
threaded portion 6a, inserted in a threaded hole formed in the
upper portion 4a of a first foot 4 of the pair, and a second
portion 6b with opposite threading inserted in a threaded hole
formed in the upper portion 4a of a second foot 4 of the pair. By
rotating lever 7 clockwise or counterclockwise, the rotation of the
worm causes feet 4 to come close to each other or to move away
along guide 5, thus varying their relative distance. In this way,
feet 4 move to portions of the sliding surfaces 3a having a
different radius, thus resulting in a variation of the fundamental
period of the damper.
[0038] The curvature of the concave cylindrical surfaces 3a of
bearings 3 may vary continuously or discretely, with more or less
marked changes in curvature between one portion of the sliding
surface 3a and another in order to obtain a larger or smaller
tuning range with the same size of the sliding surface 3a.
[0039] The tuned mass damper according to the present invention may
have more degrees of freedom, thus being able to be employed also
when more directions of motion are foreseen, e.g. two mutually
perpendicular directions.
[0040] FIGS. 8-11 show a third embodiment of the damper according
to the present invention, wherein mass 1 is supported by a first
series of feet 4 contacting a first series of bearings 3. The first
series of bearings 3 is restrained to a base 8 and the sliding
surfaces of bearings 3 are so oriented as to define a first
direction of motion marked by an arrow L. On the side of base 8
opposite the first series of bearings 3, a second series of
bearings 3' is provided, which contact a second series of feet 4'
restrained to structure 2 through corresponding guides 5' along
which they are adjustable through related driving means 6'. The
sliding surfaces 3a' of the bearings 3' of the second series are so
oriented as to define a second direction of motion, which is
perpendicular to the first one and marked by an arrow T.
[0041] Therefore, in this case the damper is provided with two
degrees of freedom in the two directions of motion defined by the
two series of bearings 3, 3'.
[0042] Other directions of motion may be similarly provided by
arranging the bearings in a multilayer structure wherein each layer
comprises a base and one or more bearings as well as a series of
feet arranged at positions corresponding to the positions of the
bearings. For each layer the direction of motion is defined by the
orientation of the sliding surfaces of the one or more bearings
arranged thereon.
[0043] In the case of a multilayer structure, the total mass of the
damper comprises not only mass 1 but also the masses of the
distinct bases 8, which are selectively activated depending on the
directions of motion simultaneously applied by an external
force.
[0044] As in the above-described embodiment provided with one
degree of freedom, in order to allow the tuning of the fundamental
period of the damper, the sliding surfaces 3a, 3a' of bearings 3,
3' have curvature radiuses transversally varying with respect to
the direction of motion defined by them and each layer comprises
driving means 6, 6' suitable for modifying the contact points
between feet 4, 4' and the sliding surfaces 3a, 3a'.
[0045] Moreover, it is possible to differentiate the damping
characteristics in the various directions of motion by using in the
various layers different controlled friction materials for the
couplings between the concave cylindrical sliding surfaces 3a, 3a'
of bearings 3, 3' and the convex cylindrical surfaces 4c, 4c' of
feet 4, 4', thus obtaining many possibilities for optimizing the
response of the damper.
[0046] It is clear that the above-described and illustrated
embodiments of the tuned mass damper are only examples susceptible
of numerous variations. In particular, it is possible to use other
controlled friction materials well known to those skilled in the
art for coating the sliding surfaces. In addition, for the sliding
surfaces made of a metal material it is possible to use special
materials like chrome-nickel steel in order to provide high
characteristics of hardness and minimize the wear.
* * * * *