Band hardness and transverse control

Abstract

This invention provides fall protection systems, in metal building construction, and methods of installing such systems, a given such system comprising a suspension fabric, supported by a grid-work of longitudinal and lateral support bands. The fall protection system uses safety clips to attach lateral bands to intermediate purlins, such that the safety clips accommodate flow-through longitudinal movement of the lateral bands through the safety clips. The invention further provides relatively softer, more extensible, support bands. The system, using the softer support bands, in combination with the flow-through longitudinal movement of the safety bands through the safety clips, distributes the impact of a falling load over an increased number of members of the structural members of the building resulting in enhanced capacity for the fall protection system to catch and hold falling loads.

Having thus described the invention, what is claimed: 
     
         1 . A fall protection system in a building roof structure, for protecting workers involved in installation of such roof structure, such building roof structure including structural roof elements including at least first and second rafters, a space between said first and second rafters defining a first distance between said first and second rafters, each said rafter having a length, a top, and opposing first and second ends, said roof structure further comprising an cave, having a length, and extending between the first ends of said first and second rafters, a ridge, having a length, and extending between the second ends of said first and second rafters, and a second distance between said cave and said ridge, said cave and said ridge being disposed on, extending transverse to, and being connected to, the tops of said first and second rafters, and a plurality of intermediate purlins extending between said first and second rafters and spaced from each other between said cave and said ridge, said intermediate purlins being disposed on, and extending transverse to, the tops of said first and second rafters, said fall protection system comprising:
 (a) a first set of support bands extending from said first rafter to said second rafter and being connected to said building structural roof elements, said first set of support bands being spaced along the lengths of said first and second rafters;   (b) a second set of support bands extending from said cave toward said ridge and under said intermediate purlins, said bands of said second set of support bands having first and second end portions and being spaced along the lengths of said eave and said ridge; and   (c) a suspension fabric overlying, and being supported by, said first and second sets of support bands, and being attached to said building structural roof elements,   
       said first and second sets of support bands collectively defining a grid of crossing bands, 
       a first band of said second set of support bands, next adjacent said first rafter, having at least one of
 (i) a yield strength of 45 ksi to 85 ksi, or 
 (ii) a tensile strength of 60 ksi to 90 ksi, or 
 (iii) an elongation of 12 percent to 40 percent, 
 
       said first band being attached to said building roof structure for restraint of longitudinal movement of said band at less than all of said intermediate purlins. 
     
     
         2 . A fall protection system as in  claim 1 , said first band having at least one of
 (i) a yield strength of 45 ksi to 75 ksi, or   (ii) a tensile strength of 65 ksi to 85 ksi, or   (iii) an elongation of 22 percent to 37 percent.   
     
     
         3 . A fall protection system as in  claim 1 , said first band having a hardness of 50 Rockwell B to 85 Rockwell B. 
     
     
         4 . A fail protection system as in  claim 2 , said first band having hardness of 55 Rockwell B to 60 Rockwell B. 
     
     
         5 . A fall protection system as in  claim 1 , said first band having a hardness of 64 Rockwell B to 79 Rockwell B. 
     
     
         6 . A fail protection system as in  claim 1 , said first band having a hardness of 70 Rockwell B to 75 Rockwell B. 
     
     
         7 . A fall protection system as in  claim 1  wherein said first band is attached to said building roof structure, for restraint of longitudinal movement, at locations spaced from each other by at least 10 feet. 
     
     
         8 . A fall protection system as in  claim 1  wherein said first band is attached to said building roof structure, for restraint of longitudinal movement, at locations spaced from each other by at least 20 feet. 
     
     
         9 . A fall protection system as in  claim 1  wherein said first band is attached to said building roof structure, for restraint of longitudinal movement, at locations spaced from each other by at least 25 feet. 
     
     
         10 . A fall protection system as in  claim 4  wherein said first band is attached to said building roof structure only at said first and second end portions. 
     
     
         11 . A fall protection system as in  claim 1 , a safety clip being attached to a bottom flange of said one of said intermediate purlins, said safety clip, either alone or in combination with said one intermediate purlin, defining an opening at or adjacent said intermediate purlin, said first band extending through such opening and wherein sides of such opening confine said first band in such opening relative to lateral movement of said first band while accommodating generally unrestricted longitudinal movement of said first band through such opening. 
     
     
         12 . A fail protection system as in  claim 11 , said first band having at east one of
 (i) a yield strength of 45 ksi to 75 ksi, or   (ii) a tensile strength of 65 ksi to 85 ksi, or   (iii) an elongation of 22 percent to 37 percent, or   (iv) a hardness of 60 Rockwell B to 79 Rockwell B.   
     
     
         13 . A fall protection system as in  claim 3 , said first band comprising a safety band, said band grid comprising a said safety band next adjacent each side of each rafter in any portion of said building roof structure where said band grid supports said suspension fabric. 
     
     
         14 . A fail protection system as in  claim 12 , said first band comprising a safety band, said band grid comprising a said safety band next adjacent each side of each rafter in any portion of said building roof structure where said band grid supports said suspension fabric. 
     
     
         15 . A fall protection system as in  claim 14  said suspension fabric extending, as a generally flat sheet, across an open expanse bounded by said first rafter, said ridge, said second rafter, and said eave, said suspension fabric being supported by said first and second sets of bands and being restrained against movement along such structural roof elements by attachments of said suspension fabric to said first and second rafters, to said eave proximate a first end of said suspension fabric and to another one of such structural roof elements proximate a second opposing end of said suspension fabric. 
     
     
         16 . A fall protection system as in  claim 14 , said fall protection system being of sufficient strength to catch and support a weight of 400 pounds, distributed over a diameter of approximately 30 inches, when dropped from a height of about 54.5 inches. 
     
     
         17 . A fall protection system in a building roof structure, for protecting workers involved in installation of such roof structure, such building roof structure including structural roof elements including at least first and second rafters, a space between said first and second rafters defining a first distance between said first and second rafters, each said rafter having a length, a top, and opposing first and second ends, said roof structure further comprising an eave, having a length, and extending between the first ends of said first and second rafters, a ridge, having a length, and extending between the second ends of said first and second rafters, and a second distance between said eave and said ridge, said eave and said ridge being disposed on, extending transverse to, and being connected to, the tops of said first and second rafters, and a plurality of intermediate purlins extending between said first and second rafters and spaced from each other between said eave and said ridge, said intermediate purlins being disposed on, and extending transverse to, the tops of said first and second rafters, said fall protection system comprising:
 (a) a first set of support bands extending from said first rafter to said second rafter and being connected to said building structural roof elements, said first set of support bands being spaced along the lengths of said first and second rafters; 
 (b) a second set of support bands extending from said eave toward said ridge and under said intermediate purlins, said bands of said second set of support bands having first and second end portions and being spaced along the lengths of said eave and said ridge; and 
 (c) a suspension fabric overlying, and being supported by, said first and second sets of support bands, and being attached to said building structural roof elements, 
 
       said first and second sets of support bands collectively defining a grid of crossing bands, 
       a first band of aid second set of support bands, next adjacent said first rafter, having at least one of
 (i) a yield strength of 50 ksi to 60 ksi, and 
 (ii) a hardness of 60 Rockwell B to 79 Rockwell B, 
 
       said first band being attached to said building roof structure for restraint of longitudinal movement of said band at less than all of said intermediate purlins, 
       a safety clip being attached to a bottom flange of said one of said intermediate purlins, said safety clip, either alone or in combination with said one intermediate purlin, defining an opening at or adjacent said intermediate purlin, said first band extending through such opening and wherein sides of such opening confine said first band in such opening relative to lateral movement of said first band while accommodating generally unrestricted longitudinal movement of said first band through such opening. 
     
     
         18 . A fall protection system as in  claim 17  wherein said first band is attached to said building roof structure only at said first and second end portions. 
     
     
         19 . A fall protection system as in  claim 17  said first band having an elongation of 22 percent to 37 percent. 
     
     
         20 . A fall protection system as in  claim 17 , said first band having a tensile strength of 65 ksi to 65 ksi. 
     
     
         21 . A fall protection system as in  claim 17  wherein said first band is attached to said building roof structure, for restraint of longitudinal movement, at locations spaced from each other by at least 10 feet. 
     
     
         22 . A fall protection system as in  claim 17  wherein said first band is attached to said building roof structure, for restraint of longitudinal movement, at locations spaced from each other by at least 20 feet. 
     
     
         23 . A fall protection system as in  claim 17 , said first band comprising a safety band, said band grid comprising a said safety band next adjacent each side of each rafter in any portion of said building roof structure where said band grid supports said suspension fabric. 
     
     
         24 . A method of providing fall protection, as a fall protection system, in a building which is under construction, for protecting workers involved in construction of such building, the building having building structural roof elements in place, including at least first and second rafters, spaced from each other by a first distance between the first and second rafters, each rafter having a length, an upper surface, and opposing first and second ends, the roof structure further comprising an eave, having a length, and extending between the first ends of the first and second rafters, the building structural roof elements further comprising a ridge, having a length, and extending between the second ends of the first and second rafters, and a second distance between the eave and the ridge, the eave and the ridge being disposed on, extending transverse to, and being connected to, the tops of the first and second rafters, and a plurality of intermediate purlins extending between the first and second rafters and spaced from each other between the eave and the ridge, the intermediate purlins being disposed on, and extending transverse to, the tops of the first and second rafters, the method comprising:
 (a) installing a first set of longitudinal support bands extending from the first rafter to the second rafter and connecting the longitudinal support bands to the building structural roof elements, the longitudinal support bands being spaced along the lengths of the first and second rafters:   (b) installing a second set of lateral support bands extending from the cave toward the ridge and under the intermediate purlins, the lateral support bands being spaced along the lengths of the cave and the ridge and supporting the longitudinal support bands, including installing, as the lateral support bands next adjacent the rafters, bands having at least one of
 (i) a yield strength of 45 ksi to 85 ksi, or 
 (ii) a tensile strength of 60 ksi to 90 ksi, or 
 (iii) an elongation of 12 percent to 40 percent; 
   (c) installing a suspension fabric over the first and second sets of support bands and under the intermediate purlins such that the suspension fabric is supported by the first and second sets of support bands;   (d) positioning one or more safety clips about the lateral support bands which are next adjacent the rafters, and attaching the respective safety clips to respective ones of the intermediate purlins, each safety clip, either alone or in combination with the respective intermediate purlin, defining an opening at or proximate the intermediate purlin, such that the respective lateral bands are attached to the respective purlins, at least in part, by the safety clips and are confined, by walls of the openings, proximate the respective intermediate purlins, against lateral movement, while experiencing generally unrestricted longitudinal movement through the openings; and   (e) positioning the remaining lateral bands up against the overlying intermediate purlins and fastening such remaining lateral bands to the respective overlying intermediate purlins.   
     
     
         25 . A method as in  claim 24  wherein the lateral support bands about which the safety clips are positioned have at least one of
 (i) a yield strength of 50 ksi to 65 ksi, or 
 (ii) a tensile strength of 65 ksi to 85 ksi, or 
 (iii) an elongation of 22 percent to 37 percent. 
 
     
     
         26 . A method as in  claim 24  wherein the lateral support bands about which the safety clips are positioned have hardnesses of 50 Rockwell B to 80 Rockwell B. 
     
     
         27 . A method as in  claim 25  wherein the lateral support bands about which the safety clips are positioned have hardnesses of 50 Rockwell B to 80 Rockwell B. 
     
     
         28 . A method as in  claim 24  wherein the lateral support bands about which the safety clips are positioned have hardnesses of 60 Rockwell B to 79 Rockwell B. 
     
     
         29 . A method as in  claim 24  wherein the lateral support bands about which the safety clips are positioned have hardnesses of 70 Rockwell B to 75 Rockwell B. 
     
     
         30 . A method as in  claim 24  wherein the first band is attached to the building roof structure, for restraint of longitudinal movement, at locations spaced from each other by at least 20 feet. 
     
     
         31 . A method as in  claim 27  wherein the first band is attached to the building roof structure only at the first and second end portions. 
     
     
         32 . A method as in  claim 24  wherein the first band has at least one of
 (i) a yield strength of 50 ksi to 65 ksi, or 
 (ii) a tensile strength of 65 ksi to 85 ksi, or 
 (iii) an elongation of 22 percent to 37 percent, or 
 (iv) a hardness of 50 Rockwell B to 80 Rockwell B. 
 
     
     
         33 . A method as in  claim 32 , the first and second sets of support bands define a band grid and wherein the lateral bands next adjacent each rafter is a safety band, the band grid comprising a such safety band, extending through a such safety clip at each intermediate purlins next adjacent each side of each rafter in any portion of the building roof structure where the hand grid supports the suspension fabric. 
     
     
         34 . A method as in  claim 33 , the fall protection system being of sufficient strength to catch and support a weight of 400 pounds, distributed over a diameter of approximately 30 inches, when dropped from a height of about 50.5 inches.