Abstract:
A system for improving the horizontal fracture resistance of older chimneys and fireplaces comprised of units of brick, stone, and the like, in response to seismic, wind, and other external lateral forces, by placing the units under a vertical internal compression stress, increasing the shear capacity between the units, by means of a clamping action. Said clamping action is the results of providing one or more elongated members attached to an element affixed at the top of the chimney and an element affixed at a lower level, said elongated members being placed under predetermined tension creating a vertical internal compression stress.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to the protection of chimneys in general and fireplace chimneys in particular against seismic or wind forces and, more particularly, to a system which can be applied to older existing stone, brick, block, and the like chimneys and fireplaces to provide such protection. 
     Modern fireplace chimneys constructed over the last several years in areas prone to seismic activity or high winds are provided with protection against those forces. Sturdy foundations and a variety of systems for tieing the fireplace and their chimney&#39;s to the structure are generally provided, as generally required by modern building codes. 
     Older fireplace chimneys are generally inadequately constructed and are prone to movement and collapse during an earthquake or high winds. This is usually due to factors such as aging, corrosion, deterioration of materials such as mortar and grout and improper installation, etc. Retrofitting these existing chimneys and their fireplaces to the standards for new construction is generally prohibitively expensive and/or impractical. Thus, there is a continuing need for improved, inexpensive, and effective systems for protecting existing stone, brick, and block chimneys. 
     This invention provides a system for retrofitting or mitigating against damage from seismic or wind forces. 
     SUMMARY OF THE INVENTION 
     Modern chimneys contain reinforcement, anchorage, and foundations which resist horizontal fracturing, as well as, lateral displacement from earthquakes or high wind forces. Older chimneys usually lack such modern reinforcement, anchorage, and foundation and are prone to damage when subjected to seismic or wind forces. Such chimneys, in general, do not conform to modern building codes. 
     This invention is a system comprised of three structural strengthening elements. One, is a clamping element which resists horizontal fracturing. The second, is the bracing element which resists lateral displacement. And, the third, is the horizontal extending foundation element which also resists lateral displacement. These three strengthening elements are summarized herein. 
     The clamping element results in a vertical internal compression stress from the top portion of the chimney, through the body of the chimney, downward to selected lower levels of the chimney or to the ground level of the chimney by means of one or more elongated tension member attached to the top of the chimney in a suitable manner, i.e., by a collar, girdle, harness or similar means engaging the upper portion of the chimney and anchoring the top end of the tension member thereto, while the lower end of the tension member is attached to selected locations along the lower level of the chimney, i.e. by using a connector or similar means of engaging the lower portion of the chimney and anchoring the bottom end of the tension member thereto, or extending the tension member further down to ground level anchoring attached to plates secured to or suitably positioned into or on the chimney or into cast-in-place concrete foundations or plates secured to or suitably positioned under the foundation of the fireplace or existing structure or straps which extend continuously under the fireplace foundation or earth type anchors and the like and placed under suitable tension. This tension exerts a predetermined degree of downward pressure upon the chimney structure, which determines the degree of internal vertical stress. 
     The tension member may be tie rods, wire rope, webbing, straps, and the like, with suitable means for providing tension, i.e. such as turnbuckles, rachet, etc. 
     The tension member should be of suitable properties to provide a predetermined internal stress and able to incorporate a means for applying the tension to the tension member the tension applied to the tension member is of such a magnitude that conformity to applicable building code requirements related to preventing horizontal fracturing is obtained. Such tension has been calculated as sufficient to produce a downward pressure in the range of 20 to 30 pounds per square inch. 
     In actual practice, the number of such tension members and the angular position thereof, will depend upon the size, shape and position of the chimney. In some cases, a single tension member may suffice. In others, two or more tension members may be required. In most cases, a pair of such members may be sufficient. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Details of the invention, and of certain preferred embodiments thereof, will be further understood upon reference to the drawings, wherein: 
     FIG. 1 is an exterior perspective view showing a typical external fireplace chimney installation utilizing one embodiment of the invention using a compression collar over the top of the chimney with tensioning attached thereto. 
     FIG. 2 is a chimney top perspective showing another embodiment of the invention utilizing a circumferential collar at or near the top and attached to the face of the chimney, with tensioning attached thereto. 
     FIG. 3 is a chimney top perspective showing another embodiment of the invention utilizing a sectional circumferential girdle type connector which is placed at or near the top of the chimney. The girdle has a bearing lip which is embedded into the mortar joint or placed over the top of the top of the chimney, with tensioning attached thereto. 
     FIG. 4 is a cross sectional view of FIG. 3 showing the bearing lip of the sectional circumferential girdle type connector. The bearing lip can be located at the top or along the height of the collar. 
     FIG. 5 is a chimney top perspective showing another embodiment of the invention utilizing a webbing harness over the top of the chimney, with tensioning attached thereto. 
     FIG. 6 is a chimney top perspective showing another embodiment of the invention utilizing a plate type gripper, gripping the bottom side of chimney and placed in a mortar joint, at or near the bottom part of the chimney with the tensioning attached thereto and showing the top end of the tensioning attached to one of the collars from FIGS. 2 to 5. 
     FIG. 7 is a chimney perspective showing another embodiment of the invention utilizing a plate type gripper, gripping the bottom side of chimney material and placed in a mortar joint, along the side of the chimney, at or near the bottom part of the fireplace with the tensioning attached thereto and showing the top end of the tensioning attached to one of the collars from FIGS. 2 to 5. 
     FIG. 8 is a chimney top perspective showing another embodiment of the invention utilizing a diagonal brace member attached to one of the compression collars from FIGS. 2 to 5 and extending away and down toward the structure and attached thereto. 
     FIG. 9 is a ground level perspective showing another embodiment of the invention utilizing a plate type gripper connector which is placed under the structure or fireplace foundation, with tensioning attached thereto. 
     FIG. 10 is a ground level perspective showing another embodiment of the invention utilizing a plate type connector attached to the side of the chimney or structure foundation, with tensioning attached thereto. 
     FIG. 11 is a ground level perspective showing another embodiment of the invention utilizing a continuous strap type connector under the chimney foundation, with tensioning attached thereto. 
     FIG. 12 is a ground level perspective showing another embodiment of the invention utilizing earth type auger anchors embedded into the earth, with tensioning attached thereto. 
     FIG. 13 is a ground level perspective showing another embodiment of the invention utilizing a horizontal extending foundation. 
     FIG. 14 is a exterior prospective view showing another embodiment where one tensioning member element may be utilized. 
     FIG. 15 is a building section showing a typical interior fireplace chimney embodiment at an interior condition showing one of the collars from FIGS. 1 to 5, and showing one of the anchoring means from FIGS. 9 to 13. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, there is seen a fireplace foundation 10 which is independent or monolithic to the structures&#39; foundation 11, formed of concrete. A fireplace exterior wall 12, typically formed of stone, brick, block, or the like, is shown with a continuing chimney wall 13, also formed of stone, brick, block, or the like. The exterior wall of the structure 14 is shown. 
     Over the top of chimney 13 is shown a compression collar or cap 15, which may be formed of welded or connected steel angles, plates and the like to which compression end connectors 16 are attached. The compression end collar connectors 16, may be formed of welded steel plates, angles, and the like with a hole to receive the tensioning member tie rods 17 and or clevis 24. 
     The pair of steel tensioning tie rod members 17 have threaded ends attached to the compression end connectors 16 with clevis type connector 24. The rod members 17 are threaded at their lower ends into turnbuckle type tensioners 19. A pair of short, threaded steel adjusting tie rods 20, are threaded into the turnbuckle type tensioners 19 and to clevis type connector 24. 
     A pair of embedded rod anchors 22, preferably made of steel and the like, with hooked lower ends which are embedded into the anchoring elements 23 and attached to the clevis type connector 24. The pair of anchoring elements 23, are formed of a cast-in-place concrete foundation which receive the rod anchors 22. 
     By tightening the turnbuckle type tensioners 19, a tension is applied to the long tension tie rods 17, the tie rod tension is resisted by the top collar 15 and the base anchoring element 23, the applied tension causes a clamping action, commonly referred to as post-tensioning in engineering terminology. 
     Referring to FIGS. 2 through 5, there is shown several alternative ways of attaching the tensioning members to the top of the chimney. In each of these alternates there is seen a chimney wall 13, formed of stone, brick, block, and the like. The exterior wall 14 of the structure is shown. Each of these alternates have a pair of long steel tension tie rods 17 which have threaded ends attached to the compression end connectors 16 with threaded fastener or clevises 24. The lower ends of the tensioning tie rods 17 are attached to the embodiments shown in FIGS. 6 and 9 to 13. 
     In FIG. 2 there is seen a circumferential collar 25 attached to the side of the chimney 13, which may be formed of welded or connected steel angles, plates and the like which is attached at or near the top of the chimney with fasteners 26. At the ends of the circumferential collar, compression end connectors 16 are attached. These may be formed of welded steel plates, angles, and the like, with a hole to receive the long tension type tie rods 17 and or clevis 24. 
     In FIG. 3 there is seen a sectional circumferential girdle type collar 27 with a bearing lip 28 shown dashed, which may be formed of welded or connected steel angles, plates and the like, and secured to the chimney face 13 by cinching. At the ends of the sectional girdle type connector 27, compression end connectors 16 are attached. These may be formed of welded steel plates, angles, and the like, with a hole to receive the long tension type tie rods 17 and or clevis 24. 
     In FIG. 4 is seen a cross section view of FIG. 3 showing the sectional circumferential girdle type collar 27 with the bearing lip 28 shown at the top. The bearing lip may be positioned at various locations on the girdle as shown dashed. 
     In FIG. 5 is seen a harness type collar 31 placed over the top of the chimney 13, the harness may be formed of steel plates or webbing materials and the like. At the ends of the harness type collar 31, compression end connectors 16 are attached to receive clevises 24 which are attached to the long tension type tie rods 17. 
     Referring to FIGS. 6 and 7, there is shown two ways of attaching the lower ends of the tensioning members 17 to the lower portions of the chimney. In each of these figures there is seen a chimney wall 13, formed of stone, brick, block and the like, and one of the compression collars 15 from FIGS. 2 to 5. Each of these have a pair of long steel tensioning tie rods 17 which have threaded ends, attached to compression collar 15 with threaded fasteners or clevis 24. 
     In FIG. 6 is seen a compression collar 27 similar to FIG. 3 at or near the top of the chimney 13. At the ends of the compression collar 17, compression end connectors 16 are attached to receive the long tension type tie rods 17 and or clevis 24. A pair of long steel tension tie rods 17, which rods are threaded at their lower ends into turnbuckle type tensioners 19. A pair of short, threaded steel tension tie rods 20, are threaded into the turnbuckle type tensioner 19 and to clevis type connector 24. The clevis type connectors 24 are attached to a invented bearing element 18 which may be formed of welded or connected steel angles, plates and the like (similar to FIG. 4) which is suitably placed in a mortar joint and engaging the bottom surface of the chimney material. 
     In FIG. 7 is seen a compression collar 27 similar to FIG. 3 at or near the top of the chimney 13. At the ends of the compression collar 27, compression end connectors 16 are attached to receive the long tension type tie rods 17 and or clevis 24. A pair of long steel tension tie rods 17, which rods are threaded at their lower ends into turnbuckle type tensioners 19. A pair of short, threaded steel tension tie rods 20, are threaded into the turnbuckle type tensioner 19 and to clevis type connector 24. The clevis type connectors 24 are attached to an invented bearing element 18 which may be formed of welded or connected steel angles, plates and the like, (similar to FIG. 4) which is suitably placed in a mortar joint and engaging the bottom surface of the chimney material 12 at a lower level. 
     Referring to FIGS. 9 through 12 there is shown several alternative ways of attaching the tensioning members to the bottom of the chimney. In each of these alternates there is seen a fireplace foundation 10 which is independent or monolithic to the structures foundation 11, typically formed of concrete. A fireplace exterior wall 12, typical formed of stone, brick, block, or the like is shown with a continuing chimney wall 13, also formed of stone, brick, block, and the like. The exterior wall of the structure is shown at 14. Each of these alternates have a pair of long steel tensioning tie rods 17 with threaded ends, which are threaded into the tensioning elements 19. A pair of short steel threaded rods 20, also threaded into the tensioning elements 19 and to the clevises type connector 24. The tensioning tie rods are attached thereto. 
     In FIG. 9 is seen a pair of long steel tension tie rods 17, which are threaded at their lower ends into turnbuckle type tensioners 19. A pair of short, threaded steel tension tie rods 20, are threaded into the turnbuckle type tensioner 19 and to clevis type connector 24. The clevis type connectors 24 are attached to a foundation gripper connection 32, formed of steel angles, plates, and the like and suitably placed under the fireplace foundation 10 or structure foundation 11. 
     In FIG. 10 is seen a pair of long steel tension tie rods 17, which are threaded at their lower ends into turnbuckle type tensioners 19. A pair of short, threaded steel tension tie rods 20, are threaded into the turnbuckle type tensioner 19 and to clevis type connector 24. The clevis type connectors 24 are attached to the foundation side plate assembly 33, formed of steel angles, plates, and the like, and attached to the sides of the fireplace foundation 10 or structure foundation 11, with concrete type fasteners 34 and the like. 
     In FIG. 11 is seen a pair of long steel tension tie rods 17, which are threaded at their lower ends into turnbuckle type tensioners 19. A pair of short, threaded steel tension tie rods 20, are threaded into the turnbuckle type tensioner 19 and to clevis type connector 24. The clevis type connectors 24 are attached to a continuous member 35, formed of steel bar, wire rope, strapping material, and the like and suitably placed under the fireplace foundation 10. 
     In FIG. 12 is seen a pair of long steel tension tie rods 17, which are threaded at their lower ends into turnbuckle type tensioners 19. A pair of short, threaded steel tension tie rods 20, are threaded into the turnbuckle type tensioner 19 and to clevis type connector 24. The clevis type connectors 24 are attached to earth type auger anchors 36, formed of steel and the like, and placed, drilled, or otherwise in the ground adjacent to the fireplace foundation 10 or structure foundation 11. 
     Other applications, variations, and ramifications of this invention will occur to those skilled in the art upon reading this disclosure. Those are intended to be included within the scope of this invention, as defined in the appended claims.