Patent Publication Number: US-7584578-B2

Title: Seismic energy damping apparatus

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to seismic energy dissipation using damping apparatus. More particularly, this invention relates to an apparatus, method, and system for absorbing and dissipating seismic energy manifest by relative movement between two members in a structure, such as a building. The systemic embodiment of this invention in a building includes plural seismic dampers and rigid shear panel members distributed or arrayed in the building so that seismic energy is absorbed and dissipated in a distributed arrangement throughout the building structure which both avoids stress concentrations in the building structure, and dissipates a greater amount of seismic energy than conventionally would be possible using concentrated damping instruments. 
   2. Related Technology 
   Seismic energy dissipation using damping devices is well known. For example, a technical paper entitled,  Seismic Response Evaluation of Post - Tensioned Precast Concrete Frames With Friction Dampers , presented at the Proceedings of the 8 th  U.S. National Conference on Earthquake Engineering, Apr. 18-22, 2006, San Francisco, Calif., USA. This paper discusses the seismic response evaluation of unbonded post-tensioned precast concrete moment frames with friction dampers at the beam ends. Another type of friction damper is illustrated in a report to the National Science Foundation, entitled, “Slotted Bolted Connection Energy Dissipaters (with April 1993 Addendum of some recent results), published in  Steel Tips , by the Structural Steel Engineering Council, Technical Information &amp; Product Service, Report No. UCB/EERC-92/10, July 1992. Slotted bolted connections (SBC&#39;s) of two types are evaluated for their ability to dissipate energy through friction. One SBC is steel-on-steel, and the other is steel-on-brass. 
   Further to the above, it is known to provide diagonal braces, either in original construction or as part of a seismic retrofit program, to brace a building having an otherwise open rectangular frame or beam structure. These diagonal braces assist in stiffening the building structure against shear forces resulting from lateral seismic ground motions, and reduce the amplitude of the displacements the building experiences in response to these shear forces. As a result, damage to the building during a seismic event is reduced, and the building will better withstand a higher level of earthquake while cost-effective construction is obtained. 
   U.S. Pat. No. 5,560,162 illustrates a variation of this diagonal bracing concept, in which the diagonal bracing is accompanied by a so-called seismic brake. The seismic brake includes a cylindrical member or pipe gripped by a gripping block. The gripping strength of the gripping block on the pipe is adjustable, so that below a certain force level, the diagonal brace acts as a rigid connection. However, if the force level between the pipe and gripping block exceeds the certain force level (i.e., as a result of a seismic event) then the pipe and gripping block move relatively to one another, the diagonal brace temporarily becomes flexible (with Coulomb damping), and seismic energy is frictionally dissipated in the seismic brake. Upon the conclusion of the seismic event, the gripping block again grips the pipe immovably, and the diagonal brace is again rigid. 
   However, the amount of seismic energy which can be dissipated by the seismic brake of the &#39;162 patent is inherently limited by the comparatively small size and extent of the brake defined between the pipe and gripping block. Also, the energy dissipation is concentrated at the gripping block and pipe, so that stress concentrations within the building structure can result. Still further, the structure of the seismic brake is rather expensive, so that building owners are hesitant to install a sufficient number of these devices to deal with predicted seismic forces. 
   SUMMARY OF THE INVENTION 
   In view of the deficiencies of the conventional related technology, it is an object of this invention to overcome or reduce one or more of these deficiencies. 
   It is an object for this invention to provide a structurally simplified seismic energy absorber or damper apparatus. 
   A further object of this invention is to provide an inexpensive seismic energy damper that can be used for structures consisting of: steel, reinforced concrete, post tensioned concrete, wood, or other materials. 
   Further, it is an object for this invention to provide such a simplified seismic energy absorber which is comparatively inexpensive and small in size, such that a multitude of the seismic energy absorbers may be distributed at low cost and in significant numbers in a distributed array in a structure, thereby to dissipate in total a greater amount of seismic energy than would otherwise be possible, and to do so within a distributed or arrayed plurality of absorbers spread about the structure, which greatly enhances the redundancy of the seismic dissipation mechanism. 
   Accordingly, one particularly preferred embodiment of the present invention provides a seismic energy damping apparatus including a pair of structure members juxtaposed to one another, and subject to relative movement during a seismic event. Each of the pair of structure members defines a respective one of a pair of holes generally aligned with one another. Each one of a pair of friction washers are connected substantially immovably to a respective one of said pair of structure members, and this pair of friction washers confront one another and define respective friction surfaces. The pair of friction surfaces cooperate with one another and move relative to one another during a seismic event to frictionally dissipate seismic energy. A resilient tie bolt extends through said aligned pair of holes and urges the pair of structure members and said pair of friction surfaces toward one another with a determined force, thus to substantially determine the frictional damping force effective between said pair of structure members and said pair of friction washers connected thereon. And, the pair of holes are oversized with respect to said tie bolt thus to provide room for said structure members to move relative to one another during the seismic event without binding on said tie bolt. 
   Accordingly, another particularly preferred embodiment of the present invention provides a seismic energy damping apparatus including a pair of members which are subject to relative motion during a seismic event, the pair of members being disposed adjacent to one another, and each of said pair of members defining a respective one of a pair of holes generally aligned with one another. At least one of said pair of members carries a first element defining a first friction surface disposed toward the other of said pair or members, the other of said pair of members carries a second element defining a second friction surface disposed toward said first friction surface. A thin friction control and damping element is interposed between said first and second friction surfaces. And, an elongate resilient tie rod member extends in said pair of holes with radial clearance accommodating said relative motion of said pair of members during a seismic event. This elongate resilient tie rod member biases said pair of members forcefully toward one another to engage said first and said second friction surfaces frictionally and movably with said interposed friction control and damping element. 
   Accordingly, still another particularly preferred embodiment of the present invention provides a method of absorbing and dissipating seismic energy, said method including steps of: juxtaposing to one another a pair of structure members which are subject to relative movement during a seismic event; providing for each of the pair of structure members to define a respective one of a pair of holes generally aligned with one another; providing a pair of friction washers each connected substantially immovably to a respective one of said pair of structure members; arranging said pair of friction washers to confront one another, and employing said pair of friction washers to define respective friction surfaces; providing for said pair of friction surfaces to frictionally cooperate with one another and to moving relative to one another during a seismic event to frictionally dissipate seismic energy; providing a resilient tie bolt extending through said aligned pair of holes and urging the pair of structure members and said pair of friction surfaces toward one another with a determined force, thus to substantially determine a frictional damping force effective between said pair of structure members and said pair of friction washers connected thereon; and configuring said pair of holes to be oversized with respect to said tie bolt thus to provide room for said structure members to move relative to one another during the seismic event without binding on said tie bolt. 
   Advantages of the present invention include that seismic energy is absorbed both in greater amount than would conventionally be possible, and the absorption of this seismic energy is distributed or spread over a greater area or volume of a building structure so that stress concentrations within the building structure are avoided; while a redundant system with significant damping characteristics is achieved. The system is capable of limiting the amplitude of the excursions (or movements) experienced by the building during a seismic event. 
   Other objects, features, and advantages of the present invention will be apparent to those skilled in the art from a consideration of the following detailed description of a preferred exemplary embodiment thereof taken in conjunction with the associated figures which will first be described briefly. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       FIG. 1  provides a simplified illustration, partly in cross section, of a seismic damping assembly according to a particularly preferred embodiment of the present invention; 
       FIG. 1A  is a fragmentary perspective view of a portion of the seismic damping assembly seen in  FIG. 1 , with parts there of omitted for simplicity and clarity of illustration; 
       FIG. 2  provides a diagrammatic illustration, partly in cross section, of an alternative embodiment of seismic damping assembly according to this invention connecting a reinforced concrete element (e.g., a slab or beam) to a steel or tube frame member; 
       FIG. 3  provides a diagrammatic illustration, partly in cross section, of yet another alternative embodiment of a seismic damping assembly according to this invention connecting a reinforced concrete element (e.g., a slab or beam) to a pair of steel tube frame members, one disposed above and the other disposed below the concrete slab or beam; 
       FIG. 4  provides a diagrammatic illustration, partly in cross section, of an alternative embodiment of a seismic damping assembly according to this invention connecting a thick or deep reinforced concrete element, (such as a slab, beam, or foundation member, for example), to a steel tube frame member; 
       FIG. 5  provides a diagrammatic illustration, partly in cross section, of yet another alternative embodiment of a seismic damping assembly according to this invention connecting a reinforced concrete element (a slab or foundation member, for example), to a steel tube frame member; 
       FIGS. 6A and 6B  in conjunction provide diagrammatic illustrations, partly in cross section, of a seismic damping assembly according to another alternative embodiment of this invention connecting a larger or principal steel tube frame member to a pair of smaller or secondary steel tube frame members, with one of the smaller frame members being disposed above and the other disposed below the principal frame member; 
       FIG. 7  provides a diagrammatic illustration, partly in cross section, of another embodiment of a seismic damping assembly according to this invention, which is somewhat similar to the embodiment of  FIG. 3 , and which connects a reinforced concrete element (such as a slab or beam) to a pair of steel tube frame members, one disposed above and the other disposed below the reinforced concrete element; 
       FIGS. 8 and 8A  respectively provide a diagrammatic illustration, partly in cross section, and a fragmentary exploded perspective view, of still another embodiment of a seismic damping assembly according to this invention, which is somewhat similar to the embodiments of  FIGS. 3 and 7 , and which connects a reinforced concrete element (slab or beam) to a pair of steel tube frame members, one disposed above and the other disposed below the reinforced concrete element; 
       FIGS. 9 and 10  respectively provide diagrammatic illustrations of a building structure having reinforced concrete or steel columns and beams, with  FIG. 9  showing the building in its normal position of repose, and  FIG. 10  illustrating the building during a seismic event involving lateral ground motion, and diagrammatically illustrates one embodiment of a steel-frame shear panel and distributed damper system; 
       FIG. 11  diagrammatically illustrates an alternative shear panel and distributed seismic damper assembly and system, in which the shear panel is constructed of concrete; 
       FIG. 12  provides a detailed illustration, partly in cross section, of one of a plurality of guide or retention members maintaining a desired relationship between the shear panel seen in  FIG. 11  and the frame of a building; and 
       FIG. 13  provides a detailed illustration, partly in cross section, viewed in the direction of arrows  13 - 13  on  FIG. 11 , of one of a plurality of seismic energy dampers as seen in  FIG. 11 ; 
   

   DETAILED DESCRIPTION OF AN EXEMPLARY PREFERRED EMBODIMENT OF THE INVENTION 
   While the present invention may be embodied in many different forms, disclosed herein are several specific exemplary preferred embodiment which illustrate and explain the principles of the invention. In conjunction with the description of these embodiments, a method of providing for seismic energy dissipation and for distributed dissipation of seismic energy in a building structure will be apparent. It should be emphasized that the present invention is not limited to the specific embodiments illustrated. 
     FIG. 1  illustrates a seismic damper, generally indicated with the arrowed numeral  10 . This seismic damper includes two members  12 ,  14 , which may, for example, be beams or slabs. These two members  12  and  14  are adjacent to one another, perhaps as part of the structure of a building. During a seismic event these two members are subjected to lateral relative motion, illustrated by the double headed arrows  16  on  FIG. 1 . As is illustrated by  FIGS. 1 and 1A  in conjunction with one another, each of the members  12  and  14  defines a through hole  18 ,  20  (only the beam  14  and hole  20  being seen in  FIG. 1A ). The through holes  18  and  20  are most preferably round in cross section, although the invention is not so limited. That is, the holes  18  and  20  could be oval, or square, or another shape in cross section if that were desired. As  FIG. 1  shows, the holes  18  and  20  are generally aligned with one another within structural tolerances, and an elongate tie bolt or rod  22  extends within the holes  18 ,  20 , and passes between the two members  12 ,  14 . Importantly, the holes  18 ,  20  are sufficiently larger than the tie bolt  22  that the motions experienced between the two members during a seismic event (recalling arrows  16 ) do not result in the tie bolt  22  binding in the holes by forceful contact at surrounding surfaces generally indicated by the arrowed numeral  24 . 
   In the embodiment of seismic damper seen in  FIGS. 1 and 1A , each of the members  12 ,  14  receives a spool assembly, generally indicated with the numeral  26 . Because each of the spool assemblies  26  is substantially the same, only the assembly carried in member  14  will be described in detail, with the spool assembly  26  carried in the member  12  being substantially the same (although inverted in position relative to the assembly  14 ). Viewing  FIG. 1 , it is seen that the spool assembly  26  includes a flanged tubular member  28  having a tubular body  30  closely received into hole  20 . The tubular body defines a through bore  32  passing the tie bolt  22  with a generous radial clearance  34 . The tubular body  30  also carries or includes an annular flange portion  36  (i.e., generally like a large washer) interposed between the two members  12 ,  14 , and defining a first friction surface  38  disposed toward the other member  12 . The flange portion  36  bears upon a surface  40  of the member  14  which is disposed toward member  12 . In this embodiment, a second friction surface  38 ′ is defined by the other spool assembly  26  carried in the other member  12 . Most preferably, the flange portions  36  of each of the spool assemblies  26  in the members  12  and  14  are made of steel. So, the friction surfaces  38  and  38 ′ are defined by steel. Interposed between the friction surfaces  38  and  38 ′ is a rather thin annular friction member  42 , which is most preferably made of brass, although the invention is not so limited. It is to be noted that the friction member  42  is optional and that the friction surfaces  38  and  38 ′ can directly engage one another. However, it is preferred to include a friction member (such as the brass friction member  42 ) between the friction surfaces  38  and  38 ′ because the nature of the Coulomb damping (i.e., frictional damping) occurring between the spool assemblies  26  (and therefore, between members  12  and  14 ) can be selected to be of a more desirable nature. 
   In order to securely attach the spool assembly  26  to member  14 , the assembly  26  also includes a second flanged tubular member  44  having a tubular body  46  closely received into hole  20 . The tubular body  46  defines a stepped through bore  48  including a smaller-diameter portion closely passing the tie bolt  22 . The tubular body  46  also defines or includes a flange portion  50  engaging surface  52  of member  14 , which is opposite to the surface  40 . The two tubular bodies  30  and  46  each define a respective thread-defining tubular portion  54  and  56 , which threadably engage one another. That is, by relative rotation of the tubular bodies  30  and  46  of the flanged tubular members  28  and  44 , the spool assembly  26  is tightened on the member  14  so that the flange portions  26  and  50  each engage tightly against the respective surfaces  40  and  52 . 
   Further to the above, the seismic damper  10  includes elongate tie bolt  22 , which as described earlier passes along the bores of the spool assemblies  26  in each of the members  12  and  14 . This tie bolt  22  at each of its opposite end portions  22 ′ receives a respective one of a pair of heavy washers  58 , and a respective one of a pair of smaller washers  60 . The pair of heavy washers respectively bear on a respective one of the spool assemblies  26  at the second flanged tubular member  44 . A respective one of a pair of nuts  62  threadably engages each end of the tie bolt  22 , and is tightened to a desired certain level to bias the friction surfaces  38 ,  38 ′ toward one another. That is, the friction surfaces  38 ,  38 ′ are biased with a determined certain force into engagement with the friction member  42 . It is to be noted that the elongate tie bolt  22 , partly because of its length, possesses a certain resilience. But, in order to provide an increased level of resilience for the tie bolt, if desired, the smaller washers  60  may be of a Belleville configuration. That is, the washers  60  may be themselves of a resilient type. Alternatively, the smaller washers  60  may be of a stress indicator type which is useful to measure or indicate the level of pre-load applied by tie bolt  22 . 
   Having observed the structure of the seismic damper  10  attention may now be directed to its operation and effect during a seismic event causing relative motion of the members  12 ,  14 , as is indicated by arrow  16 . It will be noted that below a certain force level along the direction of arrow  16 , the clamping force provided by tie bolt  22 , and the frictional engagement of the spool assemblies  26  with the friction member  42  results in a rigid connection of the members  12  and  14  to one another. Thus, during normal repose of the building or structure, for example, including the members  12 ,  14 , or during a small seismic event not sufficient to reach the certain force level, the members  12 ,  14  remain essentially immovable relative to one another. However, in the event that a seismic event is sufficiently forceful that the force level along the lines of arrow  16  reaches the certain level, then the two members  12 ,  14 , will move relative to one another (recalling arrow  16 ). This movement will result in relative movement of the two spool assemblies  26  because each is effectively locked to its respective member  12 ,  14 . Thus, the first  38  friction surface will move relative to the second friction surface  38 ′, and each moves relative to the friction member  42 . Most desirably, as mentioned above, the friction member is made of brass, which has a particularly desirable Coulomb (i.e., friction) damping characteristic when in contact with steel. That is, a steel-on-brass friction surface combination has been found to provide a uniform hysterisis. The Coulomb damping effective between the two spool assemblies  26  of the damper  10  is effective to dissipate a considerable amount of energy at the seismic damper  10 . Importantly, because of the generous radial clearance  34  between the tie bolt  22  and the surrounding surfaces  24  within the spool assemblies  26  adjacent to (or in the plane of) the friction surfaces  38 ,  38 ′, the spool assemblies do not forcefully contact the tie bolt at this location. That is, the tie bolt  22  does not bind or interfere with the movements of the members  12 ,  14  indicated by the arrow  16 . Thus, the seismic damper is free to and does dissipate a considerable amount of seismic energy. 
   Turning now to  FIG. 2 , and alternative embodiment of seismic damper is illustrated. Because the seismic damper of  FIG. 2  has many features which are the same or analogous in structure or function to those features already depicted and described by reference to  FIG. 1 , those features are indicated on  FIG. 2  with the same numeral used above, but increased by one-hundred (100). In  FIG. 2 , the seismic damper  110  connects a reinforced concrete slab or beam  64  to a steel tube frame member  66 . The members  64  and  66  are subject to relative motion indicated by arrow  116  during a seismic event. Most preferably, the steel tube frame member  66  is rectangular in cross section, so that this frame member includes an upper wall  66   u , a lower wall  66   l , a back wall  66   b , and a front wall  66   f  (which front wall is not seen in the drawing Figures but is indicated by the arrowed numeral). The upper wall  66   u  defines a rather large hole or opening  68 , the function of which will be described below. Aligned with the large upper hole  68 , the lower wall  66   l  defines a somewhat smaller hole  70 , which will be seen to provide a generous radial clearance  134  about a tie bolt  122  passing through this smaller hole. 
   Turning to the concrete slab or beam  64  seen in  FIG. 2 , it is seen that this slab or beam  64  defines a through hole  72 . Fixedly received in this through hole  72  is a spool assembly  126  in all ways comparable to the spool assembly  26  depicted and described above. This spool assembly  126  defines a first function surface  138 . However, in the seismic damper of  FIG. 2 , the steel tube frame member  66  is itself made of steel, and thus may itself be used as an active and functional part of the seismic damper  110 . That is, a respective spool assembly disposed in the steel tube frame member  66  is not required. Moreover, a portion of the lower wall  66   l  of the steel tube frame member immediately surrounding the smaller hole  70  defines a second friction surface  138 ′ which engages a friction member  142 . However, in this embodiment, a heavy washer  158  bears directly upon the upper surface of lower wall portion  66   l , and a Belleville washer  160  bears upon the heavy washer  158  and is secured by a nut  162  engaging the tie bolt  122 . As can be seen by viewing  FIG. 2 , the large hole  68  in upper wall  66   u  provides for the heavy washer  158 , Belleville washer  160 , and nut  162  to be put into place. Again, an indicator washer may be used as washer  160  for purposes of indicating the pre-load applied to tie bolt  122 . The seismic damper of  FIG. 2  functions as described above for the seismic damper of  FIGS. 1 and 1A . 
   Considering  FIG. 3 , another alternative embodiment of seismic damper is illustrated. Because the seismic damper of  FIG. 3  also has many features which are the same or analogous in structure or function to those features already depicted and described by reference to  FIGS. 1 and 2 , those features are indicated on  FIG. 3  with the same numeral used above, but increased by two-hundred (200) over  FIG. 1 , or by 100 over  FIG. 2 . In  FIG. 3 , the seismic damper  210  connects a reinforced concrete slab or beam  164  to a pair of steel tube frame member  166 / 166   a . In this case, the one frame member  166  is located above the slab or beam  164 , while the other frame member  166   a  is located below. The members  164  and  166 / 166   a  are subject to respective relative motions indicated by arrows  216  and  216 ′ during a seismic event. It is to be noted that in this case, the arrows  216 ,  216 ′ are indicative of relative motions which can be different from one another. One aspect of this relative motion  216 ,  216 ′ applies between member  164  and frame member  166 , while the other aspect appears between the member  164  and frame member  166   a.    
   Again, and most preferably, the steel tube frame members  166  and  166   a  are rectangular in cross section, so that these frame members each include a wall  166   c  (i.e., closest to the slab or beam  164 ), a wall  66   d  (i.e., distant from the slab or beam  164 ), a back wall  166   b , and a front wall  166   f  (which is not seen in the drawing Figures but is indicated by the arrowed numeral). The wall  66   d  defines a rather large hole or opening  168 , the function of which will already be clear in view of the disclosure above concerning the embodiment of  FIG. 2 . Aligned with the large holes  168 , the wall  166   d  defines a somewhat smaller hole  170 , which will be seen to provide a generous radial clearance  234  about a tie bolt  222  passing through this smaller hole. 
   Turning to the concrete slab or beam  164 , it is seen that this slab or beam  164  defines a through hole  172 . Fixedly received in this through hole  172  is a spool assembly  226  which in this case defines not only the first friction surface  238  confronting member  166 , but also defines a friction surface  238   a  confronting the member  166   a . In this case, the friction surface  238  engages a friction member  242  engaging the member  166  at second friction surface  238 ′, and the friction surface  238   a  engages a second friction member  242   a  engaging the member  166   a  at a respective second friction surface  238 ″ defined by this member  166   a . That is, the spool assembly in this instance defines respective first friction surfaces  238 ,  238   a  at each of its opposite ends, and the members  166  and  166   a  each define respective second friction surfaces  238 ′,  238 ″, which respectively engage friction members  242  and  242   a  interposed therebetween. 
   In this embodiment of  FIG. 3 , respective ones of a pair of heavy washer  258   a  and  258   b  each bear directly upon the respective wall portions  166   c  of the frame members  166  and  166   a , and respective ones of a pair of Belleville washers  160  bear upon the heavy washers  158   a ,  158   b  and are each secured by a respective nut  262  engaging the tie bolt  222 . In this case, as a result of relative movement between the slab  164  and each of the frame members  166  and  166   a , there is frictional motion between each of the spool assembly (i.e., friction surfaces  238  and  238 ′, and each of the frame members  166 / 166   a . As a result, the seismic damper  210  is able to dissipate seismic energy at both friction surfaces where relative movement is experienced. Again, in this embodiment, the washers  160  may be of the indicator type. 
     FIG. 4  provides a diagrammatic illustration of an alternative embodiment of a seismic damping assembly according to this invention connecting a thick or deep reinforced concrete beam, slab, or foundation member, for example, to a steel tube frame member. Because the seismic damper of  FIG. 4  has many features which are the same or analogous in structure or function to those features already depicted and described by reference to  FIGS. 1-3 , those features are indicated on  FIG. 4  with the same numeral used above, but increased by three-hundred (300) over  FIG. 1 , or by an appropriate increment over  FIG. 2  or  3 . It will be noted viewing  FIG. 4  that the steel tube frame member  266  is analogous to members  66  and  166  described above, and is engaged by the seismic damper  310  in the same way as was the case with the dampers of  FIGS. 2 and 3 . However, attention to the concrete beam, slab, or foundation member  76  of the embodiment seen in  FIG. 4  will reveal that the seismic damper  310  is not mechanically locked, or clamped, or tightened to the concrete structure as was the case with the earlier embodiments. That is, the seismic damper  310  of  FIG. 4  includes a spool assembly  326  which is (or may be) of a single piece. In other words, the spool assembly  326  may be formed of steel tubing and steel plate material, which are welded together to form an integral spool assembly  326 . The spool assembly  326  includes a closed end wall portion  80  defining an outwardly extending flange part  80   a , and which carries an internally threaded sleeve  82  projecting within the tubular body  330  of the spool assembly  326 . The tie bolt  322  threadably engages with the sleeve  82 . Tubular body  330  includes a flange portion  336 , which defines a friction surface  338 . 
   Importantly, viewing  FIG. 4  it is seen that the spool assembly  326  is cast into place within the concrete beam or foundation member  76  so that the body  330  and flange portion  80   a  is embedded permanently in the concrete. Alternatively, the damper  310  may be secured by use of an epoxy, for example. This aspect of the seismic damper  310  means that the seismic damper may be part of the construction from the time the concrete beam, slab, or foundation member  76  is formed, or that it may be retrofitted to such a member after construction as part of a seismic retrofit program, for example. In other respects, the seismic damper  310  of  FIG. 4  is analogous to and functions like the dampers depicted and described above. So, when the foundation member  76  is subject to motion (arrow  316 ) relative to the frame member  266 , the frictional surface  338  moves under load relative to the frictional surface  338 ′ defined by the tubular member  266 , with interposed friction member  342  determining the nature of the Coulomb damping effective at the seismic damper  310 . As a result, seismic energy is absorbed and dissipated in the damper  310 . 
   Turning now to  FIG. 5  a diagrammatic illustration of yet another alternative embodiment of a seismic damping assembly according to this invention is provided. This seismic damper embodiment connects a concrete slab or foundation member, for example, to a steel tube frame member. Importantly, and in contrast to the embodiment depicted and described by reference to  FIG. 4 , this embodiment of  FIG. 5  can be retrofit to an existing concrete structure. As will be seen in view of disclosure following below, the steel frame seen in  FIG. 5  may be part of a rigid steel frame shear panel, and the seismic damper of  FIG. 5  may be retrofit to a building or structure not having seismic capacity to resist a significant seismic demand. 
   Because the seismic damper of  FIG. 5  has many features which are the same or analogous in structure or function to those features already depicted and described by reference to  FIGS. 1-4 , those features are indicated on  FIG. 5  with the same numeral used above, but increased by four-hundred (400) over  FIG. 1 , or by a appropriate increment over  FIGS. 2-4 . It will be noted viewing  FIG. 5  that the steel tube frame member  366  is analogous to and is engaged by the seismic damper  410  in the same way as was the case with  FIGS. 2 ,  3  and  4 . However, the direction of the view in  FIG. 5  is parallel to (rather than perpendicular to) the length of the steel tube frame member  366 . Further, attention to the concrete beam, slab, or foundation member  176  of the embodiment seen in  FIG. 5  will reveal that the seismic damper  410  is not mechanically locked, or clamped, or tightened to the concrete structure as was the case with the earlier embodiments of  FIGS. 1-3 . The spool assembly  426  of this seismic damper  410  is also not cast in place in the concrete as was the case with the seismic damper  310  of  FIG. 4 . Instead, the seismic damper  410  of  FIG. 5  is especially configured to allow it to be part of a retrofit program which may be effected to an existing structure or building. 
   In order to so allow the seismic damper  410  to be fitted to an existing building structure, the damper  410  includes a spool assembly  426  having a cylindrical tubular body  430  defining or including a top flange portion  436 . This top flange portion  436  is provided with plural recessed or countersunk bold holes  436   a , through which plural fasteners  86  extend to threadably engage into the concrete slab or foundation portion  176 . That is, with an existing building structure including the slab or foundation portion  176 , a blind hole  88  is bored into the slab or foundation portion  176 , and is provided with an enlarged counter bore portion  90 . The hole  88  is sized to closely receive the tubular body  430  of the spool assembly  426 , while the counterbore  90  is sized to allow the flange  436  to set close to flush with the top surface of the slab or foundation. Thus, the spool assembly is fitted into the hole  88  and is secured by fasteners  86 . Again, an epoxy may also be used to secure, or to assist in securing, the spool assembly  426  in hole  88 . It also should be noted that the fasteners  86  could be of the expanding type, or could be anchored in epoxy, and that epoxy could be used about the assembly  426  to securely seat this assembly in the hole  88 . The anchoring resistance of the assembly  426  in hole  88  is designed to exceed the tension in tie bolt  422 . As was the case with the spool assembly  326  seen in  FIG. 4 , the spool assembly  426  of  FIG. 5  includes a threaded sleeve portion  182  for threadably receiving an elongate tie bolt  422 . The steel tube frame member  366  is provided with holes  368  and  370  allowing on the one hand access for fitting the large washer  458  and nut  462 , and on the other hand to allow the steel tube frame member  366  to be received over the projecting portion of the tie bolt  422 . Preferably, a friction member  442  is interposed between the top of flange portion  436  and friction surface  438  thereof, and the steel tube frame member  366 . The embodiment of seismic damper illustrated in  FIG. 5  functions as described above. 
   Considering now the seismic damper of  FIG. 6 , it will be seen that this damper has many features in common particularly with that embodiment of  FIG. 3 . However, the embodiment of  FIG. 3  attached an interposed concrete slab or beam to a pair of steel tubing frame members. In the embodiment of  FIG. 6 , a large or principal steel tube frame or beam member is interposed between and connected to a pair of steel tube frame members. By way of example, and as will become more clear in view of disclosure following below, the pair of steel tubing frame members may each be a respective part of a pair of rigid steel tube shear panels, disposed one above and one below the principal steel tubing frame or beam member. 
   Because the seismic damper of  FIG. 6  also has many features which are the same or analogous in structure or function to those features already depicted and described by reference to earlier drawing Figures, those features are indicated on  FIG. 6  with the same numeral used above, but increased by one-hundred (100) over their earlier or last use. In  FIG. 6 , the seismic damper  510  connects a rather large or principal steel tube frame or beam member  94  to a pair of steel tube frame member  466   a / 466   a ′. In this case, the one frame member  466   a  is located above the member  94 , while the other frame member  466   a ′ is located below. The members  94  and  466   a / 466   a ′ are subject to relative motions indicated by arrows  516 ,  516 ′ during a seismic event. One aspect of these relative motions  516 ,  516 ′ applies between member  94  and frame member  466   a , while the other aspect appears between the member  94  and frame member  466   a′.    
   Again, and most preferably, the steel tube frame members  466   a  and  466   a ′ are rectangular in cross section, so that these frame members each include a wall  466   c  (i.e., closest to the slab or beam  94 ), a wall  466   d  (i.e., distant from the slab or beam  94 ), a back wall  466   b , and a front wall  466   f  (which is not seen in the drawing Figures but is indicated by the arrowed numeral). The wall  466   d  defines a rather large hole or opening  468 , the function of which will already be clear in view of the disclosure above concerning the embodiment of  FIG. 3 . Aligned with the large holes  468 , the wall  466   d  defines a somewhat smaller hole  470 , which will be seen to provide a generous radial clearance  534  about a tie bolt  522  passing through this smaller hole. 
   Turning to the principal steel tube frame or beam  94  seen in  FIG. 6 , it is seen that this member  94  defines a through hole  472 . Fixedly received in this through hole  472  is a spool assembly  526  which in this case again defines not only the first friction surface  538  confronting beam  466   a , but also defines a friction surface  538   a  confronting the member  466   a ′. In this case, the friction surface  538  engages a friction member  542  engaging the member  466   a  at second friction surface  538 ′, and the friction surface  538   a  engages a second friction member  542   a  engaging the member  466   a ′ at a respective second friction surface  538 ″ defined by this member  466   a ′. In this embodiment, the spool assembly  526  may be welded into place within beam  94  if desired. 
   In this embodiment of  FIG. 6  also, respective ones of a pair of heavy washers  558   a  and  558   b  each bear directly upon the respective wall portions  466   c  of the frame members  466   a  and  466   a ′, and respective ones of a pair of Belleville washers  560  bear upon the heavy washers  558   a ,  558   b  and are each secured by a respective nut  562  engaging the tie bolt  522 . This embodiment of seismic damper also functions as described above. 
     FIG. 7  illustrates an alternative embodiment of seismic damper having many similarities to the embodiment of  FIG. 3 ; as well as an important difference. Again, because the seismic damper of  FIG. 7  has many features which are the same or analogous in structure or function to those features already depicted and described by reference earlier drawing Figures, those features are indicated on  FIG. 7  with the same numeral used above, but increased by one-hundred (100) over their earlier or last use. In  FIG. 7 , the seismic damper  610  connects a reinforced concrete slab or beam  564  to a pair of steel tube frame member  566   a / 566   a ′. The steel tube frame members  566   a  and  566   a ′ are rectangular in cross section, so that these frame members each include a wall  566   c  (i.e., closest to the slab or beam  564 ), a wall  566   d  (i.e., distant from the slab or beam  664 ), a back wall  566   b , and a front wall  566   f  (which is not seen in the drawing Figures but is indicated by the arrowed numeral). Each wall  566   c  defines a hole  570  providing a generous radial clearance  634  about a tie bolt  622  passing through this hole  570 . 
   Turning to the concrete slab or beam  564  of  FIG. 7 , it is seen that this slab or beam  564  defines a through hole  572 . Fixedly received in this through hole  572  is a spool assembly  626  which in this case also defines a pair of oppositely disposed first and second friction surfaces  638  and  638   a . These friction surfaces respectively confront member  566   a  and  566   a ′. In this case also, a pair of friction members  642  and  642   a  are interposed between the friction surfaces of the spool assembly  626  and the steel tube frame members  566   a  and  566   a ′. However, in this embodiment the opposite walls  566   d  of each steel tube frame member  566   a  and  566   a ′ also define a respective hole  96  about the same size as hole  570 . The tie bolt  622  in this embodiment of  FIG. 7  is thus considerably longer than was the case in the embodiment of  FIG. 3 , and passes completely through the steel tube frame members  566   a  and  566   a ′. Again, a pair of heavy washer  658   a  and  658   b  each bear directly upon the steel tube frame members  566   a  and  566   a ′, and respective ones of a pair of Belleville washers  660  bear upon the heavy washers  658   a ,  658   b  and each is secured by a respective nut  662  engaging the tie bolt  622 . Again, this seismic energy damper functions as described above. 
     FIGS. 8 and 8A  illustrate another alternative embodiment of seismic damper having many similarities to the embodiments of  FIGS. 3 and 7 . Because the seismic damper of  FIG. 8  has many features which are the same or analogous in structure or function to those features already depicted and described by reference earlier drawing Figures, those features are indicated on  FIG. 8  with the same numeral used above, but increased by one-hundred (100) over their earlier or last use. However, as will be seen, the embodiment of  FIGS. 8 and 8A  also includes provision not only for effecting Coulomb (i.e., friction) damping between the interconnected structure members, but of also effecting viscous damping between these structure members. In  FIGS. 8 and 8A , the seismic damper  710  also connects a reinforced concrete slab member or beam  664  to a pair of steel tube frame member  666   a / 6566 . The steel tube frame members  666   a  and  666   a ′ may be rectangular in cross section, although this is not required. That is, the steel tube frame members  666   a  and  666   b  could be round in cross section if desired. The concrete slab or beam  664  carries a spool assembly  726  substantially similar to the spool assembly  626  described above with reference to  FIG. 7 . The spool assembly  726  defines a pair of oppositely disposed first and second friction surfaces  738  and  738   a . These friction surfaces are defined respectively by friction members  742  and  742   a  Further, as is best illustrated in  FIG. 8A , the spool assembly  726  also includes a pair of disks  800 ,  800   a  each formed of viscoelastic (hereinafter “VE”) material. These disks  800  are each attached at one side (i.e., by bonding, for example) to the respective flange portion  736 ,  736   a  of the spool assembly  726 , and are similarly attached at the opposite side to a respective one of the friction members  742 ,  742   a . The result is that relative displacement of the friction member  742 ,  742   a  in the plane of the disks  800 ,  800   a  distorts the VE material, and results in the VE material absorbing and dissipating (i.e., by viscous damping) seismic energy. Further, as is best seen also in  FIG. 8 , about the tubular body  730  of the damper assembly  726  is disposed a sleeve member  802  also formed of VE material. In this embodiment, the sleeve  802  is closely fitted within the hole  672  formed in member  764 , such that relative motion of the damper assembly  726  and member  672  results in distortion of the VE material of sleeve  802 , and consequently results in the absorption and dissipation of seismic energy. 
   However, in the embodiment of  FIG. 8 , each of the steel tube frame members  666   a  and  666   b  also carries a respective spool assembly  98  and  98   s . These spool assemblies may be substantially the same as the spool assembly  26  described with respect to  FIG. 1 . Alternatively, the spool assemblies  98  and  98   a  my be substantially similar to the spool assembly  526  of  FIG. 6 , and each may be welded into place in the respective members  666   a ,  666   b . As was pointed out above, interposed between the respective friction surfaces of the spool assembly  726 ,  98 , and  98   a  are respective friction members  742  and  742   a . Again, in this embodiment, the tie bolt  722  is sufficiently long that it passes through both of the steel tube frame members  766   a  and  766   b , to carry heavy washers  758   a  and  758   b  each bearing respectively on the spool assembly  96 ,  98  in the steel tube frame members  766   a  and  766   b , while respective ones of a pair of Belleville washers  760  bear upon the heavy washers  758   a ,  758   b . Again, each end of the tie bolt  722  is secured by a respective nut  762  engaging the adjacent one of the pair of Belleville washers  760 . Washers  760  may be of an indicator variety, if desired. Again, this seismic energy damper of  FIG. 8  functions as described above, with the exception that at force levels lower than the certain level necessary to result in Coulomb damping at the friction surfaces, the VE material may by distortion and absorption of seismic energy, contribute also to damping of building motions even during relatively small seismic events. In the event of a significant seismic event, the friction (i.e., Coulomb) damping, and the viscous damping effected by the VE material, both contribute to damping of seismic distortions in the building structure. It is noted that there are numerous viscoelastic (VE) materials available in the market today that are used for building seismic and vibration damping. An example of these VE materials which could be used in the current inventive apparatus is a VE material known as Sorbothane®, available from Sorbothane, Inc. of Kent, Ohio. This Sorbothane®, may be used to fabricate the disks  800 ,  800   a , and sleeve member  802 , although the invention is not so limited. 
   Turning now to  FIGS. 9 and 10  considered in conjunction with one another, it is seen that  FIG. 9  illustrates diagrammatically the column and beam structure of a building or structure  910  at repose (i.e., without perturbation by a seismic event). At repose, the columns and beams may be orthogonal, although the invention is not so limited. This building  910  includes a foundation  912 , which rests upon and is connected to the ground. Raising from the foundation is seen a pair of columns  914 ,  916 . The building will include other columns as well, but for purposes of illustration, only the columns  914 ,  916  need be illustrated. These columns  914 ,  916  support spaced apart beams or floors  918 ,  920 ,  922 , and  924 . The beams or floors may be reinforced concrete. Again, the beams and columns may be orthogonal while the building is in repose, although the invention is not so limited. 
   Located between the foundation and beam  918 , and between each of the beams  920 ,  922 , and  924  are respective ones of plural shear panels  926   a ,  926   b ,  926   c , and  926   d . These shear panels  926   a/b/c/d , are each constructed of steel tubing, including a perimeter frame  928  and bracing  930  including diagonal bracing. Those ordinarily skilled in the pertinent arts will understand that the shear panels  926  may be of different shapes, and may employ different materials of construction, so that the rectangular shape for these shear panels  926  shown in  FIGS. 9 and 10  is merely illustrative. Similarly, the shear panels  926  may be made of steel plate, or of concrete, for example. As is seen in  FIG. 9 , a plurality of seismic energy dampers (represented by arrowed numerals  932 ) interconnects the shear panels  926   a/b/c/d  with the foundation  912 , and beams  918 - 924  of the building  910 . In view of the disclosure above, it may be appreciated that the seismic energy dampers  932  may be selected to be the same (or substantially the same) as the dampers depicted and described by reference to  FIGS. 1-8 . Particularly, the embodiments of  FIGS. 3 ,  6 ,  7 , and  8  are appropriate for use between the beams and shear panels. On the other hand, the embodiments of seismic damper seen in  FIG. 4  or  5  might be used to attach the shear panels to foundation  912 . 
   Turning now to  FIG. 10 , the building  910  is illustrated as it may appear when deflected during a seismic event. This seismic event includes lateral ground shift, illustrated on  FIG. 10  by arrow  934 . On the other hand, the lateral ground shift  934  results in an inertia reaction or force  936  acting on the building, principally at the floors or beams  918 - 924 . The inertia force is illustrated in  FIG. 10  by arrows  936  at each floor of the building. As a result of the seismic event and the inertia force, the building is distorted as is shown in  FIG. 10 . 
   Comparing  FIGS. 9 and 10 , it will be seen that the shear panels  926   a - d  have not distorted significantly as a result of the seismic event, but that the foundation and beams  918 - 924  are each displaced laterally relative to the adjacent one of the plural shear panels  926   a - d . As a result, each of the seismic energy dampers  932  is able to absorb and dissipate seismic energy from the seismic lateral ground shift  934 . Considering  FIGS. 9 and 10 , it is to be noted that the seismic energy dampers are arrayed or distributed within the structure of the building  910 . Thus, the absorption and dissipation of seismic energy is also distributed within the building structure, avoiding stress concentrations which might result from conventional seismic damping technology. As a result, the swaying or excursions of movement experienced by the building at each floor is markedly reduced from what would be the case where the seismic energy dampers and shear panels not present in the building structure. Consequently, damage to the building  910  from the seismic event  934  is significantly controlled. 
   Turning now to  FIG. 11 , an alternative embodiment of a shear panel structure, attaching to plural seismic energy dampers, and also attaching to the column and beam structure of a building is illustrated. The columns  1014 / 1016  and beams  1018 ,  1020  may be considered to be substantially the same as was illustrated in  FIGS. 9 and 10 . Moreover, in the embodiment of  FIG. 11 , the shear panel  938  is made of pre-cast, reinforced concrete, as will be further described. Alternatively, the shear panels  938  may be made of post-tensioned concrete. In essence, the plural seismic energy dampers  940  may each be substantially like that illustrated in  FIGS. 1 ,  2 ,  6 , or  8 . However,  FIG. 11  illustrates that the shear panel  938  is also connected to and constrained by the columns  1014 / 1016 . In order to connect the shear panels  938  to the columns  1014 / 1016 , so as to resist an inherent moment occurring in the plane of each shear panel as a result of seismic displacements, illustrated on  FIG. 11  by the circular arrow  942  (the double-headed arrow indicating that this moment may have either a clock-wise or counter clock-wise direction), the panel  938  also carries plural guide members  944 . At a particular time the moment  942  will have only a single direction, but because the building may sway back and forth, the direction of the moment  942  may reverse depending on the direction of relative movement of the shear panels  938  and building structure. It will be noted viewing  FIG. 11 , that were the moment  942  not countered, then the seismic dampers near one corner of the panel  938  would be subject to an additional normal force, while those near the opposite corner of the panel would experience a reduced normal force. The result would be an undesirably uneven distribution of seismic energy damping among the plural dampers associated with each shear panel. However, as will be seen, countering the moment  942  reduces the overturning shear demand at the ends of the beams. 
     FIG. 12  illustrates that in order to overcome the effect of the moment  942 , each of the plural guide members  944  includes a substantially rigid guide rod  946  secured in a socket  948  carried in a respective one of the columns  1014 , 1016 . This guide rod  946  is movably received in a guide spool  950  rigidly attached to the shear panel  938 . As a result, relative movements of the shear panel  938  and column  1014 / 1016  are permitted in the direction parallel to arrow  952  on  FIG. 12 . However, relative movements of the shear panel  938  and column  1014 / 1016  in the direction of arrow  954  are resisted by interaction of the guide rod  946  in socket  948 . In other words, relative movements along the arrow  954  create bending moments in the guide rod  946 , which are resisted by the substantial rigidity of this guide rod. 
   Turning now to  FIG. 13 , a fragmentary cross sectional view in the plane of the shear panels  938  is provided. As is seen in  FIGS. 11 and 13 , the shear panels define plural outwardly extending round holes  956  (arrowed on  FIG. 11 ), each opening at one end on an edge surface of the shear panel  938 . These holes  956  each open at an opposite end in a respective niche  960  opening on a face of the shear panel  938 . Each of the holes  956  of the shear panel  938  receives a spool assembly  826  (which will be familiar from the description above), as does each of plural holes  958  defined by the beams  1018 ,  1020 . The holes  956  and  958  generally align with one another within construction tolerances, so that tie bolts  822  can connect the spool assemblies  826 , as will be well understood at this point of the disclosure. A friction member  842  interposed between the friction faces or surfaces of each spool assembly  826  provides for selection of the Coulomb damping characteristic to apply between the shear panel  938  and the beams  1018 ,  1020 . As can be appreciated by viewing  FIG. 13 , the plural niches of the shear panels  938  provide for tightening of the tie bolts  822 . In view of this description, it will be understood that the seismic dampers of  FIGS. 9-13  operate as described above. However, an improved uniformity of the distribution of seismic energy absorption and dissipation is afforded by the action of the guide members  944  in resisting the overturning moment  942  inherent in the building and seismic damper structure as depicted. 
   Those skilled in the art will further appreciate that the present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof. Because the foregoing description of the present invention discloses only particularly preferred exemplary embodiments of the invention, it is to be understood that other variations are recognized as being within the scope of the present invention. Accordingly, the present invention is not limited to the particular embodiments which have been described in detail herein. Rather, reference should be made to the appended claims to define the scope and content of the present invention.