Patent Abstract:
A damping system including a first set of plates having one end thereof attached to a first vertically extending structural element, a second set of plates having one end thereof attached to a second vertically extending structural element spaced in a horizontal direction from the first vertically extending structural element, and arranged such that the first set of plates has a second end portion extending towards and overlapping with a second end portion of the second set of plates at an overlapping region, and further including an energy dissipating material provided in the overlapping region for connecting the first set of plates and the second set of plates.

Full Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the field of damping systems for buildings, bridges and other structures. In particular, it relates to a new configuration damper, for interconnecting two elements of a structure that undergo relative movements and deformations, that increases the level of damping when the overall structure is subjected to a loading condition. The new configuration damper aids in controlling displacements, forces, velocities and accelerations under dynamic loading in structural systems. 
       BACKGROUND OF THE INVENTION 
       [0002]    Modern buildings, using typical construction components such as reinforced concrete shear walls, structural steel braced frames, structural steel or reinforced concrete moment frames or combinations thereof, have low inherent damping properties. Due to this low inherent damping, high-rise buildings, in particular, tend to be susceptible to excessive vibrations caused by dynamic loads. Excessive accelerations and torsional velocities can cause occupant discomfort, while excessive displacements can cause damage to non-structural and structural elements. For this reason it is advantageous to provide additional sources of damping to control these excessive vibrations and reduce the overall building response to dynamic loads. 
         [0003]    Currently available systems for controlling displacements, forces, velocities and accelerations in such structures consist of passive systems such as supplemental dampers and vibration absorbers as well as active systems. 
         [0004]    Passive supplemental dampers such as hysteretic, viscous and visco-elastic dampers are currently used in typical braced configurations and are activated under axial deformations. While this may be effective in adding damping to some structural configurations, where under this typical braced configuration the brace elements undergo significant axial deformations, they are less effective for other structural systems, such as high rise buildings where the primary mode of lateral deformation does not cause sufficient axial deformation in typical bracing elements to actuate such dampers. In order to increase the deformations to an extent sufficient to activate the dampers, special configurations using toggle bracers or scissor braces to amplify the displacements are used. 
         [0005]    Vibration absorbers such as Tuned Mass Dampers (TMD) and Tuned Liquid Dampers (TLD) are also used to reduce the deflections, forces, velocities and accelerations of such structures. They typically consist of a mechanical vibrating system installed on the top floor of buildings in order to maximize their effectiveness. This has the disadvantage of using up some of the most valuable real estate within the building in addition to being expensive to design and to build. They also act in a limited frequency range. 
         [0006]    Active systems require an external power source, an actuating force and extensive hardware and software control systems. As a result, they are expensive to design and implement, and are susceptible to power outages or failure of the control system. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of this invention to provide a new damping system for structures which overcomes at least one of the disadvantages of the existing systems. In particular, it is an object of the invention that the damping system provides additional damping to a structure. 
         [0008]    According to one embodiment of the invention, there is provided a damping system including a first set of plates having one end thereof attached to a first vertically extending structural element, a second set of plates having one end thereof attached to a second vertically extending structural element spaced in a horizontal direction from the first vertically extending structural element. The first set of plates preferably includes a second end portion extending towards and overlapping with a second end portion of the second set of plates at an overlapping region. Also provided is an energy dissipating material in the overlapping region for connecting the first set of plates and the second set of plates. 
         [0009]    According to one aspect of this embodiment, the overlapping region is spaced from at least one or both of the first vertically extending structural element and the second vertically extending structural element. Preferably, the overlapping region is distally spaced from the one end thereof of the first set of plates and the overlapping region is distally spaced from the one end thereof of the second set of plates. 
         [0010]    According to another embodiment of the invention, there is provided a structure having a first vertically extending structural element adapted to resist lateral loads applied to the structure, a second vertically extending structural element adapted to resist lateral loads applied to the structure, a coupling member adjoining the first and second vertically extending structural elements. The coupling member preferably includes a first set of plates having one end thereof attached to the first vertically extending structural element, a second set of plates having one end thereof attached to the second vertically extending structural element, wherein the first set of plates has a second end portion extending towards and overlapping with a second end portion of the second set of plates at an overlapping region, and further including and an energy dissipating material in the overlapping region for connecting the first set of plates and the second set of plates. The coupling member provides damping for vibrations occurring in the structure due to relative movement between the first and second structural elements as the energy dissipating material damps against shearing displacement between the first set of plates and the second set of plates. 
         [0011]    According to another embodiment of the invention, there is provided a coupling member in a building structure, wherein the building structure includes first and second vertically extending structural elements adapted to resist lateral loads applied to the building structure. The coupling member connects the first and second vertically extending structural elements and includes a first set of plates having one end thereof attached to the first vertically extending structural element, a second set of plates having one end thereof attached to the second vertically extending structural element and arranged such that the first set of plates has a second end portion extending towards and overlapping with a second end portion of the second set of plates at an overlapping region, and also including an energy dissipating material provided in the overlapping region for connecting the first set of plates and the second set of plates. 
         [0012]    According to another embodiment of the invention, there is provided a damping system including a first set of plates having one end thereof attached to a first rigid extension element, the first rigid extension element connected to a first vertically extending structural element and a second set of plates having one end thereof attached to a second rigid extension element, the second rigid extension element connected to a second vertically extending structural element spaced in a horizontal direction from the first vertically extending structural element. The first set of plates preferably includes a second end portion extending towards and overlapping with a second end portion of the second set of plates at an overlapping region and an energy dissipating material is provided in the overlapping region for connecting the first set of plates and the second set of plates. 
         [0013]    Other and further advantages and features of the invention will be apparent to those skilled in the art from the following detailed description thereof, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which like numbers refer to like elements, wherein: 
           [0015]      FIG. 1A  is a side view of coupled shear wall in a typical building; 
           [0016]      FIG. 1B  is a side view of a structural steel braced frame in a typical building; 
           [0017]      FIG. 1C  is a side view of a structural steel or reinforced concrete moment frame in a typical building; 
           [0018]      FIG. 1D  is a side view of a combination of lateral load resisting systems, a structural steel braced frame and reinforced concrete shear wall in a typical building; 
           [0019]      FIG. 1E  is a side view of a combination of an outer structural column coupled to an inner shear wall in a typical building; 
           [0020]      FIG. 2A  is a side view of two shear walls in a high-rise building with the disclosed invention present coupled between walls; 
           [0021]      FIG. 2B  is a side view of a structural steel braced frame in a high-rise building with the disclosed invention present coupled between braced frames; 
           [0022]      FIG. 2C  is a side view of a structural steel or reinforced concrete moment frame in a high-rise building with an embodiment of the disclosed invention present coupled between moment resisting frames; 
           [0023]      FIG. 2D  is a side view of a combination of lateral load resisting systems, a structural steel braced frame coupled to a reinforced concrete shear wall in a highrise building with an embodiment of the disclosed invention present coupled between the steel brace frame and the concrete shear wall; 
           [0024]      FIG. 2E  is a side view of a combination of an outer structural column coupled to an inner shear wall in a typical building with an embodiment of the disclosed invention present coupled between the column and the shear wall; 
           [0025]      FIG. 3  is a series of views (orthogonal, fragmentary, plan and side elevation) of a configuration of the invention comprising four steel plates coupled to five steel plates and four layers of high damping material sandwiched there between; 
           [0026]      FIG. 4  is a pair of views (orthogonal and plan) of an alternative configuration of the energy dissipating material with a proposed anchor system and an example of the coupling zone configuration, with the damper coupled between two shear walls; 
           [0027]      FIG. 5  is a pair of views (orthogonal and plan) an embodiment of the invention in which optional extension members are used to configure the damper system to be coupled between two shear walls; 
           [0028]      FIG. 6A  is an orthogonal view of two shear walls undergoing deformation with the disclosed invention present coupled between the walls; 
           [0029]      FIG. 6B  is a close-up of the circled area B of  FIG. 6A ; and 
           [0030]      FIG. 6C  is a close-up of the circled area C of  FIG. 6A . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    Referring now to  FIGS. 1A-1E , examples of the present state of the art for the construction of mid and high-rise buildings is shown, namely using coupled reinforced concrete shear walls  114  ( FIG. 1A ), structural steel braced frames  120  ( FIG. 1B ), structural steel or reinforced concrete moment frames  130  ( FIG. 1C ), combinations thereof  140  ( FIG. 1D ), and construction with outer columns  152  (concrete or steel or any other material as used in the field of construction) and internal shear walls  156  ( FIG. 1E ). As a building is subject to wind or seismic loads, the coupling beams ( 116 ,  128 ,  134 ,  144 ,  154 ) or lateral braces ( 126 ,  148 ) are deformed, without providing any significant damping. 
         [0032]    Referring to  FIG. 1A , a structure  110  using reinforced concrete shear walls  114  has concrete coupling beams  116  located in the openings  112  between the shear walls  114 . Similarly, a structure  120  using steel columns  124  and braces  126 , as shown in  FIG. 1B  has steel coupling beams  128  located in the openings  122  between the columns  124 . An alternative steel structure  130 , consisting only of columns  132  and coupling beams  134  in the openings  136  is shown in  FIG. 1C . The structure shown in  FIG. 1D  is a combination structure  140 , with concrete shear walls  142  and steel columns  150  and braces  148  separated by an opening  146  and joined by coupling beams  144 . The final structure  150  shown in  FIG. 1E  has external columns  152 , preferably of concrete or steel, coupled to internal shear walls  156  by coupling beams  154 . 
         [0033]    In  FIGS. 2A-2E , the damping system or damper of an embodiment of the invention, generally designated  10  described herein replaces one or more of the coupling beams ( 116 ,  128 ,  134 ,  144 ,  154 ) or lateral bracing elements ( 126 , 148 ) of the structures shown in  FIGS. 1A-1E . There is no loss in interior space by doing so, as the damper  10  merely replaces the coupling beams or lateral bracing and fits within the area otherwise occupied by the coupling beams or lateral bracing. However, for some applications a damper  10  of larger depth, up to the height of an entire story, can be used to replace the coupling beam, if required. In doing so, when the building is subject to dynamic wind or seismic loads, the damper  10  is deformed and provides supplemental damping to the system. 
         [0034]    Referring variously to  FIGS. 3-5 , the damping system  10  is comprised of a first set of steel plates  310  interdigitated with a second set of one or more similar steel plates  312  and coupled thereto by way of interposed layers of energy dissipating material  320  firmly adhered thereto by layers of adhesive or other bonding means. The ends of the two sets of plates opposite the coupled ends are structurally engaged with a pair of adjacent lateral load resisting elements  330  i.e. concrete shear walls, by embedding the ends therein or by bolting the ends to the walls in secure fashion. The plates  310 ,  312  are sufficiently rigid to provide the necessary structural integrity to the building and to follow the movement of the lateral load resisting elements  330 , thus accentuating the differential movement between the two ends of the lateral load resisting elements  330 , which in turn shears the energy dissipating material  320  between the two sets of plates  310 ,  312 .  FIG. 3  discloses an example of a configuration of the damping system comprising four plates  310  connected to five plates  312 . The four plates  310  are coupled to the five plates  312  by way of disks of energy dissipating material  320 . There are eight layers of energy dissipating material  320  that undergo shear deformations when the lateral load resisting elements  330  to which they are attached undergo lateral deformations. 
         [0035]    The energy dissipating material  320  used is a high damping rubber or a high damping visco-elastic material or any other material capable of dissipating energy (either displacement dependent, or velocity dependent). 
         [0036]      FIG. 4  discloses another example of a damping system  10  according to the invention and comprising a first set of four plates  410  connected as in  FIG. 3  to a second set of five plates  412  by larger, rectangular shaped sections of energy dissipating material  420 . Variations in the number of plates used, and the length, width, thickness and shape of the energy dissipating material can be used to tune the damping system to the particular application to maximize its damping effect. Furthermore,  FIG. 4  discloses an anchorage system  414  at one end of the plates  412  for anchoring the damping system  10  to the lateral load resisting elements  430 . 
         [0037]      FIG. 5  discloses a configuration of the damping system  10  where the energy dissipating portion of the damper  510  is separately constructed and then connected to rigid extension elements  520 , which, in turn are configured to be structurally engaged with the lateral load resisting elements  530  at a later time, for example at a construction site. In the configuration shown, the plates are joined together in sets for coupling to the rigid extension elements. 
         [0038]      FIG. 6A  discloses a structure  610  undergoing lateral deformation. The coupling beams  616  connecting the shear walls  614  are deformed, as well as the damping system  10 .  FIG. 6B  shows a close-up of a coupling beam  616  under deformation. As the shear walls  614  shift, they undergo a rotation by an amount shown by arrows A-A, and the coupling beam  616  is deformed from the base chord  640  by a corresponding amount shown by arrow  642 . The deformation of coupling beam  616  is a rotational effect arising from the lateral displacement of shear walls  614 .  FIG. 6C  shows a close-up of a damping system  10  under deformation in the same manner. It can be seen that the rigid extension elements  630  do not deform, but instead laterally displace, and deformation is restricted to the energy dissipating elements  635  (shown shaded). Thus, minimal rotational deformation takes place. 
         [0039]    Preferred embodiments of the invention thus utilize the in-plane relative deformations, in both orthogonal directions, and in-place differential rotations, between two or more lateral load resisting structural elements, regardless of composition, to provide additional damping. 
         [0040]    They provide a damping system that is relatively inexpensive, compared to current damping systems. 
         [0041]    The preferred embodiments further provide a damping system capable of being installed without significant changes to the architectural and structural configuration of the building structure in which it is to be installed, and one that is easily constructed and provides a simple replacement for conventional damping systems. 
         [0042]    While the embodiment of the invention described herein relates to buildings subjected to lateral loads such as wind loads, seismic loads, and blast loads, other useful applications of this invention, including, but not limited to other structures, will be apparent to those skilled in the art. 
         [0043]    This concludes the description of a presently preferred embodiment of the invention. The foregoing description has been presented for the purpose of illustration and is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching and will be apparent to those skilled in the art. For example, while the plates constituting the first and second sets have been described as made from steel, any material sufficiently rigid to provide the necessary structural integrity to the building and to follow the movement of the lateral load resisting elements such as walls or beams could be used, such as other metals and alloys, high strength resin reinforced composites and the like. Also, the energy dissipating material can be chosen from a wide variety of materials, such as natural or synthetic rubber (SBR, polybutadiene, polyisoprene, butyl, etc.), a choice which is within the skill of the art. It is intended the scope of the invention be limited not by this description but by the claims that follow.

Technology Classification (CPC): 5