BACKGROUND OF THE INVENTION

a. Field of the Invention

The present invention relates generally to earthquake shock dampers and, more particularly, to an improved earthquake shock damper suitable for use at load bearing points in pillars, columns, bridges, buildings and other structures.

b. Related Art

Bridges, elevated highways, buildings and other large structures are often constructed in areas where earthquake protection for the structure is required. In many of these structures, the structural integrity is highly dependent on capacity of the load bearing points to survive the stresses imposed during an earthquake. Although a structure may be able to withstand the loss of one or more load bearing points (e.g., load bearing pillars or columns), each failure increases the load on the rest of the structure and makes it more likely that the entire structure will fail. Thus, it is critical to provide shock dampers or other devised that prevent load bearing points from failing under the forces in moments generated during an earthquake: These loads include horizontal and vertical forces, as well as twisting and bending moments. The form of the load bearing points will vary with the nature of the structure, e.g., the corners of a building or the columns supporting an elevated roadway. Moreover, the shock dampers may be located at load bearing points between the structure and an underlying foundation, referred to as "base isolation", or elsewhere, as between the tops of pillars or columns and an overlying roadway, for example. One prior form of shock damper that has provided protection for load bearing points, and that can be used to protect the load bearing pillars and columns, is that shown in U.S. Patent Nos. 5,657,588 and 6,085,471, both of which are incorporated herein by reference. The dampers disclosed therein employ a male plug and female receptacle separated by a resilient, cast-in-place urethane insert. The vertical load- bearing interface is configured to permit a degree of relative movement between the plug and receptacle, so that earthquake shock loads are absorbed and damped by deformation of the elastomeric insert. Although the apparatus disclosed in U.S. Patent Nos. 6,085,471 and 5,657,588 have been successful in many respects, areas for improvement have remained in terms of efficiency and dynamic response. For example, the urethane material of the prior devices is, for practical purposes, loaded only in compression, in part because significant tension loading has the potential for causing rupture of the material where this interfaces with the male plug member and the female receptacle. The use of the cast-in-place urethane insert, in which the urethane is poured and cured between the male and female members, also complicates manufacture, since in most instances this means that the damper must be fabricated, transported and installed as a complete, comparatively bulky unit; furthermore, any errors in casting the urethane insert may result in the entire assembly having to be scrapped. Moreover, in terms of dynamic response, it has been found that providing the correct degree of frictional engagement at the vertical load-bearing interface is a critical factor in most installations. Specifically, the static co-efficient of friction controls the amount of shear force that is transmitted to the structure up to the point at which sliding initiates; then, once sliding initiates, the shear force that is transmitted to the structure is dependent on the dynamic co-efficient of friction at the sliding interface, not the magnitude of the earthquake. For example, it is important that the static co-efficient of friction not be so high as to cause the interface to "stick" in a way that would compromise the ability of the assembly to absorb shock loads in the event of an earthquake; at the same time, it is important that the dynamic co-efficient of friction not be so low that the interface moves excessively under normal working loads (traffic, wind, etc.), nor so low that the interface will continue to move for an excessive time after a seismic event. Moreover, it is important that the static and dynamic coefficients of friction be both consistent and predictable so that the apparatus can be properly engineered. With the prior dampers described above, however, it has been found that achieving the desired consistency and control is difficult, which greatly complicates the process of properly engineering the assemblies for different structures and installations. Accordingly, there exists a need for an earthquake damper assembly for protecting the load bearing points of bridges, buildings, elevated roadways, and other structures that has an improved and more efficient design. Furthermore, there exists a need for such a shock damper in which the frictional engagement between the vertical load-bearing surfaces is predictable and readily controlled and engineered. Still further, there exists a need for such a shock damper in which the components can be economically manufactured, and can be transported and installed separately, if desired, and that does not require the use of a cast-in-place resilient insert. SUMMARY OF THE INVENTION

The present invention has solved the problems cited above, and is an earthquake shock damper assembly comprising (a) a first coupling member that is mountable to a first portion of a structure; (b) a second coupling member that is mountable to a second potion of the structure; (c) a bearing surface on the first coupling member; (d) an articulated slider mounted on the second coupling member in vertical load bearing engagement with the bearing surface on the first coupling member, the articulated slider comprising: (i) a shoe member that is formed of high strength material and mounted to the second coupling member so as to be pivotable thereon; and (ii) an insert that is formed of a controlled friction material and mounted to the shoe member in contact with the bearing surface on the first coupling member so as to form a sliding interface therewith; and (e) a resilient member that is mounted between the first and second coupling members so as to provide a restoring force in response to relative displacement of the first and second coupling members due to an earthquake shock load. The shoe member of the articulated slide may comprise a hemispherically- contoured base portion that engages a cooperating hemispherically-contoured portion of the second coupling member in pivoting engagement therewith. The hemispherically-contoured base portion of the shoe member may be convexly hemispherical and the cooperating hemispherically-contoured potion of the second coupling member may comprise a concavely hemispherical socket on the second coupling member that receives the base portion of the shoe member therein. The insert formed of a controlled friction material may comprise a surface of the controlled friction material that protrudes distally from an upper portion of the shoe member so as to form a spaced gap between the shoe member and the bearing surface that is contacted by the controlled friction material. The insert may comprise a generally disc-shaped piece of the controlled friction material, and the upper portion of the shoe member may comprise a generally circular recess having the disc-shaped piece of controlled friction material mounted therein, the recess being bordered by a shoulder of the upper portion of the shoe member having a surface that faces towards the bearing surface on the first coupling member. The shoe member may be formed of metal and the controlled friction insert may be formed of substantially nonmetallic material. The nonmetallic material of the controlled friction insert may comprise a fluoropolymer resin woven composite material or cast nylon material. The nonmetallic material of the controlled friction insert may undergo resilient compression in response to vertical shock loads that are imparted to the assembly, and the spaced gap by which the controlled friction insert separates the shoe member from the bearing surface may be sized to allow the insert to undergo compression up to a predetermined limit, so that at the predetermined limit the surface of the shoulder on the metal shoe comes into contact with the bearing surface so as to prevent further compression of the nonmetallic insert. The second coupling member may comprise a male coupling member having a base portion and a central post, the hemispherical socket being formed in a distal end of the post. The first coupling member, in turn, may comprise a female coupling member having a base portion and a surrounding wall that receives the post of the male coupling member centrally therein, the bearing surface being contained within the surrounding wall. The resilient member may comprise a generally annular-shaped restoring force member mounted intermediate the central post of the male coupling member and the surrounding wall of the female coupling member. The restoring force member may comprise a generally annular elastomeric member, a rigid inner ring that engages the central post of the male coupling member, and a rigid outer ring that engages the surrounding wall of the female coupling member, the rigid inner and outer rings being mounted to the annular elastomeric member so that the elastomeric member provides resistance in both compression and tension in response to lateral displacement of the male coupling member relative to the female coupling member. The rigid inner and outer rings may comprise inner and outer metal rings that are bonded to the elastomeric member, and the elastomeric member may be formed of elastomeric natural rubber. In a preferred embodiment, the present invention provides an earthquake shock damper assembly for protecting a structure, the shock damper assembly comprising: (a) a female coupling member that is mountable to a first portion of the structure, the female coupling member comprising: (i) a base for being mounted to the first portion of the structure, (ii) a generally cylindrical wall that extends from the base about a vertical axis of the assembly so as to form a receiving area, and (iii) a substantially planar bearing surface that is mounted in the receiving area and extends substantially perpendicular to the wall of the female coupling member; (b) a male coupling member that is mountable to a second portion of the structure, a male coupling member comprising: (i) a base for being mounted to the second portion of the structure, and (ii) a generally cylindrical post that extends from the base of the male coupling member along the vertical axis of the assembly, the post having a generally hemispherically concave socket at a distal end thereof; (c) an articulated slider in vertical load-bearing engagement between the female coupling member and the male coupling member, the articulated slider comprising: (i) a pivoting shoe comprising a generally hemispherically convex base end that is received in the hemispherically concave socket in the distal end of the post, a generally circular recess formed in a distal end of the shoe, and a distally facing shoulder that extends generally annularly around the recess, and (ii) a disc of controlled friction material that is mounted in the recess in contact with the bearing surface on the female coupling member so as to form a sliding interface therewith, the controlled friction material having a surface that protrudes from the distal end of the shoe member so as to form a spaced gap of predetermined size between the bearing surface and the annular shoulder of the shoe member; and (d) a restoring force member mounted between the female and male coupling members so as to provide a restoring force in response to relative displacement of the female and male coupling members by an earthquake shock load, the restoring force member comprising: (i) a generally annular elastomeric member, (ii) a rigid, generally cylindrical inner ring that engages the cylindrical post of the male coupling member, and (iii) a substantially rigid, generally cylindrical outer ring that engages the cylindrical wall of the female coupling member, the rigid inner and outer rings being bonded to the annular elastomeric member so that the elastomeric member provides resistance in both compression and tension in response to lateral displacement of the male coupling member relative to the female coupling member. These and other features and advantages of the present invention will be more fully understood from a reading of the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a shock damper assembly in accordance with the present invention, with the wall of the upper, female member partially cut away to show the internal components of the assembly; FIG. 2 is a cross-sectional view, taken vertically through the damper assembly of FIG. 1 , showing the relationship of the male and female members, the articulated slider and the resiliently compressible insert in greater detail; FIG. 3 is a cross-sectional, exploded view of the damper assembly of FIGS. 1- 2, showing the configuration of the components thereof in greater detail; FIG. 4 is a cross-sectional view, similar to FIG. 2, of the damper assembly of FIGS. 1-3, showing the manner in which the assembly is mounted to the opposing ends of an exemplary column by means of radial flanges on the base portions of the male and female members of the assembly; FIG. 5 is a perspective view of the articulated slider of the damper assembly of FIGS. 1-3 showing the manner in which a disc of fictional material is mounted within the recess in the distal end of the slider; FIG. 6 is a perspective view of the resilient restoring force insert of the damper assembly of FIGS. 1-3, showing the manner in which the elastomeric component thereof is bonded to inner and outer metallic bands; FIGS. 7-8 are first and second plan, schematic views of the resilient insert of FIG. 6, showing the manner in which the elastomeric material of the insert provides resistance in both compression and tension as the inner and outer bands are displaced laterally in response to shock loads generated by an earthquake; and FIGS. 9-10 are graphs comparing the restoring forces generated by example elastomeric inserts, with FIG. 9 showing the response of a plain rubber insert that resists the displacement only in compression and FIG. 10 showing the response of a rubber insert having inner and outer steel rings bonded thereto so that the insert resists displacement in both compression and tension. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For purposes of illustration, the present invention is shown herein primarily in the context of a load-bearing pillar or column, such as those which support overpasses, bridges, and other elevated structures. It will be understood that the applicability of the present invention is not limited to load-bearing pillars and columns, however, and that the invention may be used with the load bearing points of buildings and many other types of structures. Accordingly, FIG. 1 shows an earthquake damper assembly 10 in accordance with the present invention. As can be seen, the principal components include a male coupling 12, a female coupling 14, an articulated slider 16, and an elastic restoring force element 18. Each of these components will be described in greater detail below. As can be seen in FIG. 2 and FIG. 3, the male coupling 12 includes a generally circular base plate 20 having centrally located, columnar pedestal 22. An annular mounting flange 24 is formed about the perimeter of the coupling and includes a plurality of spaced bores 26 for passage of bolts or other fasteners therethrough. The bottom side of the flange is co-planar with that of the base plate to form a mounting surface 28 for engaging the end of a load-bearing column or other part of a structure, as will be described in greater detail below. The center post 22 is also formed integrally with the base plate 20. As compared with the corresponding components of the previous devices described above, the post 22 has a cylindrical (as opposed to tapered) outer surface, and cooperates with the inner ring of the restoring force element 18 as described below. The upper end of the post has an annular, inward bevel 30, and includes a hemispherically concave cup 32 for receiving the articulated slider 16. The male member 12, as well as the female member 14, may be constructed of any suitable high-strength, rigid material. Machined 4140 steel or other high strength steel is eminently suitable, with the surfaces of the members being treated for corrosion resistance. All inside corners are preferably radiussed, as seen in FIG. 3, to minimize concentration of stress. Similar to the male member, the female housing 14 includes a base plate 34 having a flat mounting surface 36 that extends outwardly to a mounting flange 38 having a plurality of bolt holes 40. An annular, cylindrical wall 42 depends from the base plate and defines the shell of a cylindrical opening 44 for receiving the elastomeric restoring element 18. An annular, inwardly projecting shoulder 46, formed part-way up the inside of shell wall 42, provides a stop for the upper edge of the elastomeric insert so as to form an open chamber 48 for the articulated slider 16, as will be described in greater detail below. The lower side of the base plate 34 forms a flat, circular surface 50 that is circumscribed by the shell wall 42. A circular bearing plate 52 having a matching configuration is mounted (e.g., welded or adhered) to the circular lower surface of the base plate. The bottom, bearing surface of the plate 52 is polished to provide substantially uniform coefficient of friction at the sliding interface with the frictional insert of the articulated slider. Stainless steel is generally preferred for the bearing plate 52 due to its excellent corrosion resistance, in that the sliding interface must be able to perform consistently over the entire design life of the structure in which it is installed; suitably, the surface is ASTM A-240 Type 316 (or alternatively, Type 304) polished to a Degree No. 8 mirror finish. The use of a separate bearing plate 52 simplifies the polishing process and is therefore generally more economical, however, it will be understood that in some embodiments the polished surface may be formed directly on the lower, inside surface of the female member itself rather than on a separate plate. The articulated slider 16, in turn, is composed of a pivoting shoe or puck 54 having a disc-shaped insert 56 formed of frictional material. As can be seen in FIG. 5, the upper (distal) end of the pivoting shoe 54 includes a shallow, circular recess 58 that is bordered by a raised, annular shoulder 60. As indicated by the dotted line in FIG. 5, the disc of frictional material 62 mounted within the circular recess 58 so as to be surrounded by the distally-facing shoulder 60. The recess 58 and shoulder 60 are formed at the top of a generally cylindrical body 64 of the shoe 54. The lower portion of the shoe, in turn, is formed with a downwardly extending hemispherical surface 66. When loaded, the hemispherically convex shape of the surface 66 cooperates with the concavely hemispherical socket 32 at the top of post 22 to allow small rotations of the shoe 54 in all directions, thereby ensuring that contact is made with the polished surface of the wear plate over substantially the entire surface area of the disc-shaped friction insert 56. The components - the circular bearing plate and insert and the hemispherical socket and shoe base - thus cooperate to establish a sliding interface having a substantially uniform mechanical response in all directions. The material of which the insert 56 is formed, in turn, controls the static and dynamic co-efficiency of friction at the interface itself. A preferred factional material for the insert is a fluoropolymer (e.g., polytetrafluoroethylene) woven composite; a second preferred frictional material is cast nylon. Other suitable materials may be employed, however, the fluoropolymer resin woven composite is generally preferred for several reasons, including consistent low-friction characteristics, high load capacities, and good wear/durability characteristics. With regard to the latter quality, it will be appreciated that although large-magnitude movement of the sliding interface due to seismic events is a comparatively rare occurrence, small, almost constant movement of the interface due to live loads under normal conditions will typically cause at least several kilometers of travel to accumulate over the lifetime of the structure. Suitable fluoropolymer resin woven composite materials include but are not limited to those using fluoropolymer resins in combination with glass, carbon, polyester, Kevlar™ and other fibers, and are commercially available in sheet form from which the disc-shaped inserts can be cut or machined. A principal benefit of the frictional insert (as opposed to a metal-to-metal or other plain interface) is the improved ability to adjust the static/dynamic coefficients of friction to meet specific design and installation requirements. To begin with, both coefficients of friction can be increased or decreased by increasing or decreasing the diameter of the insert. Moreover, the frictional material itself can be modified to adjust the static and dynamic coefficients of friction; this is particularly true in the case of the fluoropolymer resin woven composite frictional materials, in which the configuration and/or compositions can be adjusted (as known to those skilled in the relevant art) to produce materials with graduated frictional characteristics. Consequently, it is possible to use a single design of articulated slider and provide it with greater or lesser static and dynamic coefficients of friction by simply substituting different grades of the material for the disc-shaped friction insert. As a result, the frictional engagement of the sliding interface can be precisely engineered to cooperate with the resilient restoring force member in a manner that meets the requirements of a particular application or installation. For example, certain applications, such as bridges, require comparatively "stiff dampers so as to avoid excessive movement of the structure under normal, "live" loads (such as traffic/wind loads and thermal expansion/contraction) as well as to prevent excessive swaying of the structure during a seismic event; consequently, in such installations it may be preferred to use a frictional insert having high static/dynamic coefficients of friction in combination with a high-durometer elastomeric insert so as to minimize movement under normal loads and quickly dissipate energy from seismic shocks. On the other hand, a damper for a building may utilize a frictional insert having lower static/dynamic coefficients of friction in combination with an elastomeric insert formed of a lower durometer material so as to provide a "softer" response which lessens likelihood of damage to the building and its contents. Still other applications may call for combining of higher-friction sliding interfaces with lower-durometer elastomeric members, or vice-versa. The present invention's use of articulated slider and restoring force elements having adjustable frictional and restoring force characteristics greatly facilitates proper engineering of the dampers for all such applications. As can be seen in FIG. 2, the height of the frictional insert 56 relative to the depth of the circular recess 58 is such that the upper surface of the frictional material protrudes a short distance above (distally of) the shoe 54, thereby creating a short vertical gap 68 between the shoulder 60 of the shoe and the overlying metal plate 52 on the female housing. This arrangement ensures that the sliding interface is formed entirely by the surface of the frictional material, not by the metal material of the shoe. The gap 68 is sized to permit a predetermined degree of compression ("squeezing") of the frictional material (e.g., the fluoropolymer resin woven composite or cast nylon) under vertical loads, with the annular shoulder 68 serving to confine the perimeter of the material so as to restrain it from deforming outwardly (i.e., spreading) while undergoing compression. Beyond a predetermined limit, however, the ability of the material to establish a satisfactory co-efficient of friction and/or maintain its physical integrity may become compromised: the height of the gap 68 is preferably sized to allow compression of the frictional material to a point near or at this limit, beyond which continued vertical compression causes the plate 52 to move into direct contact with the annular shoulder of the shoe 54. The metal materials of which the shoe and post 22 are constructed are for practical purposes incompressible, so that the shoulder 60 acts as a stop that limits vertical compression of the frictional material. The frictional insert will generally be sized (e.g., in height and diameter) with respect to anticipated seismic events such that it will be unlikely that the shoulder will actually come into contact with the bearing plate during the life of the assembly. However, in the event of an unexpectedly high vertical loading, the engagement of the incompressible shoulder 60 with the plate 52 will prevent failure of the frictional material and ensure that a viable sliding interface is maintained, although it will be understood that the characteristics of the interface created by direct contact between the bearing plate and the metal shoulder will generally be less than optimal. As was noted above, the hemispherical interfit between the lower portion 66 of the shoe and the socket 32 at the top of post 22 enables the former to rotate by small amounts in any direction. As can be seen in FIG. 2, the height of the cylindrical upper portion 64 of the shoe is such that a gap 70 of predetermined height is formed between it and the upper end of the post 22 in order to accommodate the pivoting motion of the shoe. Similarly, the height of the shell wall 42 is sized relative to the height of the post 22, shoe 54 and insert 56 to form a peripheral gap 72 that accommodates the rocking/pivoting motion of the female member relative to the male member. As was also noted above, and as can be seen in FIG. 2, the resilient restoring force member 18 is sized to fit intermediate the post 22 of the male member and the shell wall 42 of the female member. The resilient insert provides restoring force in response to seismic shock loads that cause both lateral and pivoting displacement of the female member relative to the male member. As a result, the energy of the shock loads is dissipated in a cooperative fashion by both the resistance of the resilient insert and the friction at the sliding interface between the male and female members. As can be seen in greater detail in FIG. 6, the restoring force member 18 is composed of a donut-shaped elastomeric insert 74 bonded to rigid inner and outer rigid rings 76, 78. The inner and outer rings 76, 78 have generally cylindrical configurations, so as to cooperate with the cylindrical outer surface of the post 22 of the male member and the cylindrical inner surface of the shell wall 42 of the female member. The inner and outer rings 76, 78 are suitably formed of a substantially rigid metal, e.g., steel. The elastomeric insert 74, in turn, is formed of any suitable elastomeric material. However, natural rubber formulations are generally preferred for the elastomeric insert, primarily because it generally exhibits a greater resistance to rupture than most cast urethane compositions or similar materials; in particular, commercially available, AASHTO (American Association of State Highway and Transportation Officials) approved natural rubber formulations having a Shore Hardness between Durometer 20 and Durometer 90 have been found eminently suitable for the insert. It will be understood, however, that other suitable elastomeric materials may be used; for example, polyurethane formulations may be employed in certain applications where the damper will be exposed to extremes of cold or heat that are outside the optimal ranges for most natural rubber formulations. The restoring force member 18 can therefore be manufactured on an economical basis by casting the natural rubber or other elastomeric material of the desired durometer in the space between the inner and outer metallic rings 76, 78, with the opposing faces of the rings suitably being provided with scoring, knurling or other surface texturing so as to enhance the bond between the metal and the rubber material when cured. Although steel rings are employed in the preferred embodiment, it will be understood that some embodiments may utilize non-metallic rings; moreover, it will be understood that in some embodiments the rings may be formed by inner and outer portions of the elastomeric insert itself that are given an increased rigidity/hardness relative to the main body of the material, as by addition of a material or specialized curing, for example. The diameters of the inner and outer rings 76, 78 are sized so that these meet in close-fitting interface with the corresponding cylindrical, vertically extending surfaces on the center post 22 and shell housing 42. As a result, the predominant, lateral displacement forces are transmitted into the elastomeric material of the insert with a high degree of efficiency; as an incidental but still significant benefit, the calculations necessary to design the resilient insert for predetermined lateral forces are also greatly simplified, thus rendering it much more economical to engineer the inserts for a variety of applications. More importantly, the bonded inner and outer rings 76, 78 ensure that lateral displacement forces are resisted by the elastomeric material in both compression and tension. This greatly increases the overall efficiency of the assembly, as compared with the prior devices in which the elastomeric material resisted lateral displacement essentially only in compression. This latter benefit is illustrated in FIGS. 7-8, in which the elastomeric component 74 is shown with radial and annular grid or mesh lines 80 that illustrate deformation and therefore the loading of the material. FIG. 7 shows the insert in an undisplaced condition, with the inner ring 76 at an initial, static center C, with the undistorted grid lines 80 indicating an even distribution of force in the elastomeric member 74. FIG. 8, in turn, shows the loading of the elastomeric insert when the inner ring 76 is shifted relative to the outer ring 78, to a laterally displaced center C, as due to a seismic shock load: As is indicated by the distortion of the grid lines 80, the zone 82 of the elastomeric material in front of the inner ring 76 (i.e., in the direction of advance towards the outer ring) resists the lateral displacement force in compression; the zone 84 of elastomeric material behind the inner ring 76, in turn, resists the lateral forces in tension, due to the bonding of the material to the rigid metal of both the inner and outer rings. As a result, resilient restoring force insert 18 is far more efficient in resisting lateral displacements than the prior designs noted above, which resisted displacement only in compression. This difference can be seen by a comparison of FIGS. 9 and 10, which illustrate the restoring force generated by two identically-sized elastomeric inserts, the first being a plain elastomeric insert and the second having the bonded steel rings, both inserts being subjected to a displacement having an amplitude of 45 millimeters and a rate of 0.5 millimeters per second. As can be seen, the peak restoring force generated by the element with the bonded rings (FIG. 10) is roughly twice that of the element that lacks the rings (FIG. 9). This tremendous increase in efficiency enables the assembly to utilize significantly more compact and economically manufactured components, thus reducing the cost of both manufacture and installation. FIG. 4 shows an installation of the shock damper assembly 10 in an exemplary load-bearing pillar. As can be seen, the assembly is mounted in a gap between the end faces 86, 88 of upper and lower segments 90, 92 of the pillar. Each of the end faces 86, 88 is substantially flat so as to form a more-or-less continuous, face-to-face load-bearing abutment with the corresponding flat mounting surfaces 36, 28 of the mounting flanges of the male and female coupling members. Bolts 94 or other suitable fasteners are passed through the bores 40, 26 of the upper and lower flanges and threaded into anchors 96 embedded in the ends of the pillar segments 90, 92. Similar types of installation can be made, for example, between a floor and a foundation or between the upper end of a pillar and a roadway or the other structure that is supported thereon. The anchors may be of any suitable type compatible with the material of the structure, which in many installations will be concrete; in other installations, the male and female members may be bolted, welded or otherwise mounted directly to the material of the structure or building without the use of anchors, and the mounting flanges may also having varying configurations for different types of installations. Because the restoring force member and male and female coupling members are fabricated as separate pieces, the physical transportation and installation of the assembly is in many cases considerably easier than with the prior dampers described above. Moreover, the increased efficiency of the design allows the dampers of the present invention to have a significantly smaller external size than their predecessors of equal capacity, again easing installation and making it possible to use the dampers in a wider range of applications. In addition to the components that are shown in FIG. 4, the assembly may be provided with means for preventing separation of the male and female members in the event that a seismic event causes an overturning or parting force to be generated between the ends of the column segments, such as external or internal brackets or shoulders that come into engagement to hold the members together. Furthermore, a flexible seal or other mechanism may be included (e.g., between the base of the male member and the cylindrical wall of the female member) to prevent condensation from entering the assembly and possibly causing corrosion of the internal surfaces and components. Sizing of the components will depend on the design requirements for a particular installation. For purposes of illustration, however, the dimensions of one example of a shock damper assembly in accordance with the present invention are set forth in the following Table A: TABLE A

Male Coupling Member

Overall diameter including mounting flange 304.80 mm Diameter of base plate portion 234.95 mm Diameter of center post 63.50 mm Diameter of post top socket 38.10 mm Overall height including center post 108.71 mm Height of mounting flange 21.59 mm Height of base plate portion 43.18 mm Height of center post above base plate portion 65.53 mm Post top bevel 50.0 "I°O Female Coupling Member

Overall including mounting flange 304.80 mm Outside diameter of shell wall 234.95 mm Inside diameter of shell wall at shoulder 203.20 mm Inside diameter of shell wall below shoulder 208.28 mm Overall height including shell wall 99.06 mm Height of mounting flange 22.22 mm Height of shell wall below mounting flange 76.835 mm Height of inside of shoulder below mounting flange 26.035 mm Thickness of bearing plate (stainless steel) 03.175 mm

Pivoting Shoe Member

Overall diameter 50.80 mm Diameter of the recess 38.10 mm Radius of hemispherical load portion 19.05 mm Overall height 31.75 mm Height of cylindrical upper portion 12.70 mm Depth of recess 01.575 mm Thickness of fluoropolymer resin woven 1.60 mm composite disc (with backing)

Restoring Force Member

Overall diameter including outer ring 204 mm Thickness of elastomeric element, i.d. to o.d. (50 Shore Durometer natural rubber) 62 mm Thickness of outer steel ring 5 mm

Thickness of inner steel ring 3 mm Overall height 50 mm The example of damper assembly having the foregoing dimensions is a comparatively small unit, and, as noted above, it will be understood that other assemblies will have differing dimensions depending on design requirements. The foregoing description provides just one example of many possible constructions, configurations, and materials for implementing the present invention. Various alternative configurations and materials may be equally adequate for delivering the attributes that the preferred embodiment provides. It is therefore to be recognized that various alterations, modifications, and/or additions may be introduced into the constructions and arrangements of parts described above without departing from the spirit or ambit of the present invention as defined by the appended claims.