Patent Publication Number: US-2021180634-A1

Title: Masonry hardware

Description:
FIELD 
     This invention relates to masonry hardware in particular clay brick or soft stone block fasteners and wall ties. 
     BACKGROUND 
     Loadbearing cavity (aka hollow) wall construction is a form of masonry wall construction where two leaves of unreinforced clay brick masonry or soft stone block masonry (URM) are separated by a continuous air cavity. In recent times the two leaves are interconnected using some form of tie system. In earlier times a tie system was not used. Observations of building damaged in earthquakes and strong winds indicated that failure of URM construction, typically cavity walls, was critical in terms of structural stability and safety issues, and collapse of the outer masonry cavity wall layer due to wall bending failure was commonly encountered. Also observed was the poor quality of masonry construction, mortar strength and cavity wall ties that often corroded, resulting in a poor connection between the two masonry wall layers. Therefore, the capacity of wall ties to transfer lateral load was significantly diminished due to cross-sectional reduction. In a similar manner inadequate or missing shear and tension connections between the unreinforced masonry (URM) bearing wall and the floor or roof can cause issues. The most significant deficiency in URM bearing wall buildings is the lack of an adequate positive (i.e. mechanical) tie between the masonry walls and the floor and roof diaphragms. Ties are usually separated into two categories: tension ties and shear ties. Tension ties transfer out-of-plane inertial loads perpendicular to the face of the masonry back into the structural elements. Shear ties transfer loads from the structural elements into the wall where they are resisted by in-plane action of the wall. Tension ties help keep the walls from falling away from the diaphragms; shear ties help keep the diaphragm from sliding along parallel to the wall. 
     SUMMARY 
     According to one example embodiment there is provided a masonry fastener, comprising:
         a shank having a first and second portions, a tip at one end and a head at a second distal end, the shank having ductility measured as a bending angle under complete three repeated cycles without rupture of between about 10.0° and 22.0°;   the first portion having a tapered helical screw portion along a predetermined longitudinal length thereof, the tapered helical screw portion commencing at a tip and extending partially towards the head; and   the second portion having a tapered helical screw portion along a predetermined longitudinal length thereof, the tapered helical screw portion commencing at the first portion and ending at the head.       

     Preferably the masonry is clay brick or soft stone masonry. 
     Preferably the clay bricks or stone blocks have up-to 35 MPa compression strength. 
     Preferably the bending angle is about 21.0°. 
     Preferably the tapered helical screw portions have a thread spacing of between about 6 mm and about 10 mm. 
     Preferably the thread spacing is about 8 mm. 
     Preferably the shank has a diameter between about 6 mm and about 10 mm. 
     Preferably the shank diameter is about 8 mm. 
     Preferably the shank has a length between about 160 mm and about 340 mm. 
     According to a further example embodiment there is provided a masonry wall tie, comprising:
         a shank having a first, second and third portions and a first and second end, the shank having ductility measured as a bending angle under complete three repeated cycles without rupture of between about 12.5° and 26°;   the first portion having a tapered helical screw portion along a predetermined longitudinal length thereof, the tapered helical screw portion commencing at a tip at the first end;   the second portion being unthreaded and extending between the first and third portions; and   the third portion having a tapered helical screw portion along a predetermined longitudinal length thereof, the tapered helical screw portion commencing at the second portion and extending to the second end.       

     Preferably the masonry is clay brick or soft stone masonry. 
     Preferably the clay bricks or stone blocks have up-to 35 MPa compression strength. 
     Preferably the bending angle is about 25.7°. 
     Preferably the tapered helical screw portions have a thread spacing of between about 5.5 mm and about 10 mm. 
     Preferably the thread spacing is about 6 mm. 
     Preferably the shank has a diameter between about 5.5 mm and about 10 mm. 
     Preferably the shank diameter is about 6 mm. 
     Preferably the second unthreaded portion is between about 25% and about 30% of the wall tie length. 
     Preferably the second unthreaded portion is about 28% of the wall tie length. 
     Preferably the second unthreaded portion length is between about 60 mm and about 90 mm. It is acknowledged that the terms “comprise”, “comprises” and “comprising” may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, these terms are intended to have an inclusive meaning—i.e., they will be taken to mean an inclusion of the listed components which the use directly references, and possibly also of other non-specified components or elements. 
     Reference to any document in this specification does not constitute an admission that it is prior art, validly combinable with other documents or that it forms part of the common general knowledge. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings which are incorporated in and constitute part of the specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description of embodiments given below, serve to explain the principles of the invention, in which: 
         FIG. 1  is a diagram of an embodiment of a wall tie connecting two masonry wall made of clay bricks or soft stone blocks; 
         FIG. 2  is an isometric view of the wall tie shown in  FIG. 1 ; 
         FIG. 3  is a side view of the wall tie shown in  FIG. 1 ; 
         FIG. 4  is a side view of the wall tie shown in  FIG. 1  with the proportions shown; 
         FIG. 5  is a close-up view of the threads of the wall tie shown in  FIG. 1 ; 
         FIG. 6  is a top view of the wall tie shown in  FIG. 1 ; 
         FIG. 7  is a bottom view of the wall tie shown in  FIG. 1 ; 
         FIG. 8  is a cross section of the head of the wall tie shown in  FIG. 1 ; 
         FIG. 9  is a diagram of an embodiment of a fastener connecting a wooden support to masonry including clay bricks and soft stone blocks; 
         FIG. 10  is an isometric view of the fastener shown in  FIG. 9 ; 
         FIG. 11  is a side view of the fastener shown in  FIG. 9 ; 
         FIG. 12  is a cross sectional side view of the fastener shown in  FIG. 9 ; 
         FIG. 13  is a top view of the fastener shown in  FIG. 9 ; 
         FIG. 14  is a bottom view of the fastener shown in  FIG. 9 ; 
         FIG. 15  is an isometric view of the fastener shown in  FIG. 10  in a further embodiment; 
         FIG. 16  is a side view of the fastener shown in  FIG. 15 ; 
         FIG. 17  is a cross sectional side view of the fastener shown in  FIG. 15 ; 
         FIG. 18  is a top view of the fastener shown in  FIG. 15 ; and 
         FIG. 19  is a bottom view of the fastener shown in  FIG. 15 . 
     
    
    
     DETAILED DESCRIPTION 
     It may be desirable to create minimally intrusive and reversible strengthening (earthquake and/or wind loading retrofit) options for unreinforced masonry buildings with cavity type walls. The wall may be made of clay bricks or soft stone blocks. The clay brick may be fired clay bricks. Further it may be desirable to create a composite interconnection action between separate wall layers in unreinforced masonry buildings with cavity type walls. 
     The material strength of clay bricks or soft stone blocks/units can be vastly variable. The soft stone block material includes but are not limited to sandstone, limestone, tuff, or similar. The wall ties and fasteners discussed herein are applicable for use with stone blocks having up-to 35 MPa compression strength. Similar compression strength applies to fired clay brick. 
       FIGS. 1 to 8  illustrates a clay brick or soft stone block wall tie  200  according to an example embodiment. 
     The clay brick or soft stone block wall tie  200  connects unreinforced clay bricks or soft stone blocks  220 ,  225 . 
     The clay brick or soft stone block wall tie  200  includes a shank having a first threaded portion  240  extending from the tip  242  of the clay brick or soft stone block wall tie  200  partially along the shank. 
     A third portion  230  is also threaded. 
     A second unthreaded portion  235  extends between the first threaded portion  240  and the third threaded portion  230 . The diameter of the unthreaded portion  235  is in one embodiment of a greater diameter that the center core diameter of the first and third threaded portions  230 ,  240 . The threads of the first portion  230  and third portion  240  are preferably sharp crested helical threads formed along the clay brick or soft stone block wall tie  200  shank. 
     Notches  245  may be formed on the crest of the helical thread along the length of the screw, more frequent end notches (saw teeth) may be formed in about the first three revolutions at the tip  242  in order to facilitate embedment of the crest into the masonry substrate 
     The notches  245  may facilitate embedment of the crest of the helical threads into the masonry substrate of the clay bricks or soft stone blocks. 
     The clay brick or soft stone block wall tie  200  forms an anchor device which is designed to be secured within a bore formed in a multi-leaf (wythe) masonry wall structure. 
     The clay brick or soft stone block wall tie  200  fasten itself into multi-leaf (wythe) masonry when it is screwed and will not be loosen from vibrations or use (such as earthquake or wind induced). 
     The thread  244  of the clay brick or soft stone block wall tie  200  is designed to cut a spiral groove into the masonry substrate when inserted into a predrilled hole and turned. The spiral groove cuts without damaging the surround clay brick or soft stone blocks. 
     The clay brick or soft stone block wall tie  200  is turned by a head  250  on the clay brick or soft stone block wall tie  200 . The head  250  has in one embodiment a torx head  260 , however other suitable head types including hex, square recess, pozi, p Phillips, slotted and hex head cap screw may be used. 
     The clay brick or soft stone block wall tie  200  may be suitable as a replacement of original wall ties and may provide high tensile capacity for earthquake and wind resistance of cavity and veneer type masonry construction. 
     Further the clay brick or soft stone block wall tie  200  may provide a high level of interleaf shear transfer for enhanced earthquake and wind resistance and may be used to secure multiple layers of masonry for a resilient interconnected masonry wall cross-section. 
     The clay brick or soft stone block wall tie  200  may be used without no resin or grout and there is no mechanical expansion. The clay brick or soft stone block wall tie  200  provides a quick, easy, non-disruptive installation. 
     In one embodiment the clay brick or soft stone block wall tie  200  may be recessed below face of masonry as seen in  FIG. 1 . 
     The clay brick or soft stone block wall tie  200  threaded portions  230 ,  240  will typically have a thread spacing of between about 5.5 mm and about 10 mm. Preferably the thread spacing is about 6 mm. 
     The clay brick or soft stone block wall tie  200  shank diameter is between about 5.5 mm and about 10 mm. Preferably the shank diameter is about 6 mm. 
     The clay brick or soft stone block wall tie  200  shank length is between about 200 mm and about 340 mm depending on the size of the clay brick or soft stone block and the space between the clay bricks or soft stone block. In one embodiment the length is 240 mm. 
     While illustrated and described in reference to double brick or block cavities, the clay brick or soft stone block wall tie  200  could be used in a triple brick or block situation. In this situation the first or third threaded portions would be lengthened to suit depending on whether or not the double brick or block layer of a triple brick or block cavity was being passed through or screwed into. 
     The clay brick or soft stone block wall tie  200  is preferably manufactured using tempered steel to provide ductile response. Other materials (manganese, carbon, silicon, aluminum, phosphorus) may be used that provide a good ductile response. 
     EN 14592 provides a ductility measure with the level of performance measured from S1 to S3. S3 being the highest level. The test requires a fitting being bent three times to a bending angle. The degrees of bendability using this measure is expressed as: 
     
       
         
           
             a 
             = 
             
               
                 4 
                  
                 5 
               
               
                 d 
                 
                   0 
                   . 
                   7 
                 
               
             
           
         
       
     
     α is expressed in degrees and d is the nominal diameter of the shank, in mm. 
     Ductility class S3 requires three repeated cycles at the bending angle before breaking of S3=2×α 
     In a typical embodiment 
     
       
         
           
             a 
             = 
             
               
                 
                   4 
                    
                   5 
                 
                 
                   d 
                   
                     0 
                     . 
                     7 
                   
                 
               
               = 
               
                 
                   
                     4 
                      
                     5 
                   
                   
                     6 
                     
                       0 
                       . 
                       7 
                     
                   
                 
                 = 
                 
                   1 
                    
                   
                     2 
                     . 
                     8 
                   
                    
                   4 
                 
               
             
           
         
       
     
     and 
         S 3=2×α=12.84×2=25.7
 
     Thus, the clay brick or soft stone block wall tie  200  would typically have a bending angle of about 25.7°. In a preferred embodiment the bending angle under complete three repeated cycles without rupture would be between about 12.5° and 26°. 
     The clay brick or soft stone block wall tie  200  may be installed using the following installation procedure:
         Mark the position for the masonry cavity screw on the face of the near brick/block leaf.   Drill a suitable diameter pilot hole through the near leaf and into the back-up substrate, to predetermined depth, using a rotary percussion drill. Using the preferred diameter clay brick or soft stone block wall tie  200  the hole would be 6 mm   Drill a hole for the countersinking of the head  250 .   Insert the clay brick or soft stone block wall tie  200  into pre-drilled hole.   Manually or power-drive the clay brick or soft stone block wall tie  200  into position until its outer end is recessed below the face of the near leaf.   Make good the entry hole with matching materials (if needed).       

     In a further embodiment a clay brick or soft stone block fastener  400  illustrated in  FIGS. 9 to 19  may be used for adding timber or metal strong backs to clay bricks or soft stone blocks, connecting plywood or wooden panels to clay bricks or soft stone blocks. Other uses may include attaching shear studs (or dowels) for concrete layer application, connecting steel elements to clay bricks or soft stone blocks and connecting timber elements to clay bricks or soft stone blocks. 
     Referring to  FIGS. 9 to 19  the clay brick or soft stone block fastener  400 , has a shank having a first  485  and second portions  480  and a tip  442 . 
     The first portion  485  has a tapered helical screw  444  along the longitudinal length of the first portion  485 . The tapered helical screw commencing at a tip of the first end thereof and ending at the second portion. The tapered helical screw type of the first portion is optimised for clay bricks or soft stone blocks. 
     The second portion  480  has a tapered helical screw along a longitudinal length thereof. The tapered helical screw of the second portion  480  commences at the end of the first portion  485  and end at the head  450 . The tapered helical screw type of the first portion is optimised for timber. 
     Notches  445  may be formed on the crest of the helical thread along the length of the screw, more frequent end notches (saw teeth) may be formed in about the first three revolutions at the tip  442  in order to facilitate embedment of the crest into the masonry substrate 
     The notches  445  may facilitate embedment of the crest of the helical threads into the masonry substrate of the clay bricks or soft stone blocks. 
     In other embodiments such as attaching metal to clay bricks or soft stone blocks the first and second portions may have a continuous thread type optimised for clay bricks or soft stone blocks. 
     The shank of the clay brick or soft stone block fastener  400  has ductility measured as the bending angle under complete three repeated cycles discussed above. 
     EN 14592 provides a ductility measure with the level of performance measured from S1 to S3. S3 being the highest level. The test requires a fitting being bent three times to a bending angle. The degrees of bendability using this measure is expressed as: 
     
       
         
           
             a 
             = 
             
               
                 4 
                  
                 5 
               
               
                 d 
                 
                   0 
                   . 
                   7 
                 
               
             
           
         
       
     
     α is expressed in degrees and d is the nominal diameter of the shank, in mm. 
     Ductility class S3 requires three repeated cycles at the bending angle before breaking of S3=2×α 
     In a typical embodiment 
     
       
         
           
             a 
             = 
             
               
                 
                   4 
                    
                   5 
                 
                 
                   d 
                   
                     0 
                     . 
                     7 
                   
                 
               
               = 
               
                 
                   
                     4 
                      
                     5 
                   
                   
                     8 
                     
                       0 
                       . 
                       7 
                     
                   
                 
                 = 
                 
                   1 
                    
                   
                     0 
                     . 
                     5 
                   
                 
               
             
           
         
       
     
     and 
         S 3=2×α=10.5×2=21.0
 
     Thus, the clay brick or soft stone block fastener  400  would typically have a bending angle of about 21.0°. In a preferred embodiment the bending angle under complete three repeated cycles without rupture would be between about 10° and 22°. 
     The shank diameter of the clay brick or soft stone block fastener  400  is between about 6 mm and about 10 mm. Preferably the shank diameter is about 8 mm. 
     The tapered helical screw  444  portions  480 ,  485  of the clay brick or soft stone block fasteners  400  have a thread spacing of between about 5.5 mm and about 10 mm. Preferably the thread spacing is about 8 mm. 
     The thread  444  of first portion  485  of the clay brick or soft stone block fasteners  400  is designed to cut a spiral groove into the masonry substrate when inserted into a predrilled hole and turned. The spiral groove cuts without damaging the surround clay brick or soft stone block. 
     The thread  444  of second portion  480  of the clay brick or soft stone block fasteners  400  is designed to cut a spiral groove into timber or the like when inserted into a predrilled hole and turned. 
     The clay brick or soft stone block fasteners  400  is turned by a head  450  on the clay brick or soft stone block fasteners  400 . The head  450  has in one embodiment a torx head  460 , however other suitable head types including hex, square recess, pozi, p Phillips, slotted and hex head cap screw may be used. 
     The clay brick or soft stone block fasteners  400  shank length is between about 200 mm and about 400 mm but the length may be adjusted to suit the use of the clay brick or soft stone block fasteners  400 . Likewise the proportion of the shaft optimized for screwing into brick/block or wood may be altered depending on the use. 
     The clay brick fasteners  400  is preferably manufactured using tempered steel to provide ductile response. Other materials (manganese, carbon, silicon, aluminum, phosphorus) may be used that provide a good ductile response. 
     The clay brick fasteners  400  may be installed using the following installation procedure:
         Mark the position for the masonry cavity screw on the face of the timber.   Drill a suitable diameter pilot hole through the timber and into the brick/block, to predetermined depth, using a rotary percussion drill. Using the preferred diameter fasteners  400  the hole would be 8 mm   Insert the clay brick or soft stone block fasteners  400  into pre-drilled hole.   Manually or power-drive the clay brick or soft stone block fasteners  400  into position until its outer end is recessed below the face of timber.   Make good the entry hole with matching materials (if needed).       

     Uses of the clay brick or soft stone block fasteners  400  may include masonry parapet securing; masonry wall to additional member connections (such as steel or timber strong-backs); and use as tension and shear dowels. 
     Additional uses of the clay brick or soft stone block fasteners  400  may include connecting plywood or wooden panels to clay bricks or soft stone blocks and use as masonry wall interleaf ties in cases such as poor interleaf (wythe) interconnection and where danger of delamination of the wall cross-section exists. 
     While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant&#39;s general inventive concept.