Staggered truss system with controlled force slip joints

Abstract

A truss for use in a staggered truss system in provided. The truss includes at least one slip joint for allowing relative movement between the top chord of the truss and the bottom chord of the truss. The staggered truss system may be suitable for use in seismic regions.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . A truss for use in a staggered truss system, comprising:
 a top chord extending in a first direction;   a bottom chord spaced from the top chord and extending in parallel with the top chord;   at least one vertical web member positioned between the top and bottom chord;   at least one diagonal web member positioned between the top and bottom chord; and   at least one slip joint positioned at the interface of the top chord and the at least one vertical web member, the slip joint configured to connect the top chord to the at least one vertical web member in a manner that prohibits relative movement between the top chord and the vertical web member when a lateral load less than a preselected value is applied while allowing relative movement between the top chord and the vertical web member along the first direction when a lateral load greater than a preselected value is applied.   
     
     
         2 . The truss of  claim 1 , wherein the slip joint includes:
 an attachment plate secured to the top of the vertical web member, the attachment plate positioned underneath a section of the top chord;   a shim positioned between the attachment plate and the section of the top chord, the shim having a coefficient of friction; and   a fastener arrangement configured to connect the top chord to the attachment plate,   wherein the shim and one of the attachment plate and the section of the top chord include at least one slot elongated in the first direction and generally aligned with one another, and wherein the fastener arrangement includes a bolt that extends through the generally aligned slots and a hole in the other of the one of the attachment plate and the section of the top chord and a nut that affixes the bolt in place.   
     
     
         3 . The truss of  claim 2 , wherein the bolt translates within the elongated slots as the top chord slips along the first direction with respect to the attachment plate. 
     
     
         4 . The truss of  claim 2 , wherein the nut and bolt are cooperatively tensioned so that the top chord slips along the first direction with respect to the attachment plate when a load greater than a preselected value is applied. 
     
     
         5 . The truss of  claim 4 , wherein the tension applied by the nut and bolt and the shim material are selected so that the top chord slips along the first direction with respect to the attachment plate when a load greater than a preselected value is applied. 
     
     
         6 . The truss of  claim 5 , wherein the preselected value is dependent of lateral loads generated in seismic events. 
     
     
         7 . The truss of  claim 2 , wherein the shim includes a material selected from a group consisting of high strength steel, mild steel, stainless steel, brass, Babbitt metal, aluminum, PTFE, high density polypropylene, and high density polyethylene. 
     
     
         8 . The truss of  claim 1 , wherein the top chord and the web members are constructed of steel. 
     
     
         9 . The truss of  claim 1 , further including a second vertical web member spaced from the first vertical web member, and a compression member disposed between the first and second vertical web members. 
     
     
         10 . The truss of  claim 1 , wherein the compression member is disposed adjacent the attachment plate. 
     
     
         11 . A staggered truss system comprising two or more trusses according to  claim 1 . 
     
     
         12 . A truss for use in a staggered truss system, comprising:
 a top chord extending in a first direction;   a bottom chord spaced from the top chord and extending in parallel with the top chord;   at least one vertical web member positioned between the top and bottom chord;   at least one diagonal web member positioned between the top and bottom chord; and   at least one slip joint positioned at the interface of the top chord and the at least one vertical web member, the slip joint including:
 an attachment plate secured to the top of the vertical web member, the attachment plate positioned underneath a section of the top chord; 
 a shim positioned between the attachment plate and the section of the top chord, the shim having a coefficient of friction and a plurality of slots elongated in the first direction; and 
 a fastener arrangement configured to connect the top chord to the attachment plate, wherein 
 one of the attachment plate and the section of the top chord include a plurality of slots generally sized and aligned with the slots of the shims and the other of the plate and the section of the top chord includes a plurality of holes, and wherein the fastener arrangement includes a bolt that extends through the generally aligned slots and the holes and a nut that affixes the bolt in place. 
   
     
     
         13 . The truss of  claim 12 , wherein the nut and bolt are cooperatively tensioned so that the top chord slips along the first direction with respect to the attachment plate when a load greater than a preselected value is applied. 
     
     
         14 . The truss of  claim 12 , wherein the bolt translates within the elongated slots as the top chord slips along the first direction with respect to the attachment plate. 
     
     
         15 . The truss of  claim 12 , further including a second vertical web member spaced from the first vertical web member, and a compression member disposed between the first and second vertical web members. 
     
     
         16 . The truss of  claim 15 , wherein the compression member is disposed adjacent the attachment plate. 
     
     
         17 . The truss of  claim 12 , wherein the shim includes a material selected from a group consisting of high strength steel, mild steel, stainless steel, brass, Babbitt metal, aluminum, PTFE, high density polypropylene, and high density polyethylene. 
     
     
         18 . The truss of  claim 12 , wherein the chords and the web members are constructed of steel. 
     
     
         19 . A staggered truss system comprising two or more trusses according to  claim 12 . 
     
     
         20 . A truss for use in a staggered steel truss system, comprising:
 a top chord extending in a first direction;   a bottom chord spaced from the top chord and extending in parallel with the top chord;   at least one vertical web member positioned between the top and bottom chord;   at least one diagonal web member positioned between the top and bottom chord; and   means for connecting one of the top chord and the bottom chord to the at least one vertical web member in a manner that allows slip between the vertical web member and said one of the top chord and the bottom chord along the first direction when a lateral load greater than a preselected value is applied.   
     
     
         21 . The truss of  claim 20 , wherein the applied lateral load is a seismic load. 
     
     
         22 . The truss of  claim 20 , wherein the shim includes a material selected from a group consisting of high strength steel, mild steel, stainless steel, brass, Babbitt metal, aluminum, PTFE, high density polypropylene, and high density polyethylene. 
     
     
         23 . A staggered truss system comprising two or more trusses according to  claim 20 . 
     
     
         24 . A truss for use in a staggered truss system, comprising:
 a top chord extending in a first direction;   a bottom chord spaced from the top chord and extending in parallel with the top chord;   at least one vertical web member positioned between the top and bottom chord;   at least one diagonal web member positioned between the top and bottom chord; and   at least one slip joint positioned at the interface of the bottom chord and the at least one vertical web member, the slip joint configured to connect the bottom chord to the at least one vertical web member in a manner that prohibits relative movement between the bottom chord and the vertical web member when a lateral load less than a preselected value is applied while allowing relative movement between the bottom chord and the vertical web member along the first direction when a lateral load greater than a preselected value is applied.   
     
     
         25 . The truss of  claim 24 , wherein the slip joint includes:
 a top attachment plate secured to the vertical web member;   a bottom attachment plate secured to the bottom chord;   a shim positioned between the top and bottom attachment plates, the shim having a coefficient of friction and at least one slot elongated in the first direction; and   a fastener arrangement configured to connect the top attachment plate to the bottom attachment plate,   wherein the top or bottom attachment plate includes at least one slot elongated in the first direction and generally aligned with the slot of the shim, and wherein the fastener arrangement includes a bolt that extends through the generally aligned slots and a hole in the other of the top or bottom attachment plate and a nut that affixes the bolt in place.   
     
     
         26 . The truss of  claim 25 , wherein the applied lateral load that is greater than the preselected value is a seismic load. 
     
     
         27 . The truss of  claim 25 , wherein the shim includes a material selected from a group consisting of high strength steel, mild steel, stainless steel, brass, Babbitt metal, aluminum, PTFE, high density polypropylene, and high density polyethylene. 
     
     
         28 . The truss of  claim 24 , wherein the chords and the web members are constructed of steel. 
     
     
         29 . A staggered truss system comprising two or more trusses according to  claim 24 . 
     
     
         30 . A staggered truss system, comprising:
 three or more trusses positioned in a staggered orientation, each truss including
 a bottom chord spaced from the top chord and extending in parallel with the top chord; 
 at least one vertical web member positioned between the top and bottom chord; 
 at least one diagonal web member positioned between the top and bottom chord; and 
 at least one slip joint positioned at the interface of the bottom chord and the at least one vertical web member, the slip joint configured to connect the bottom chord to the at least one vertical web member in a manner that allows slip between the bottom chord and the vertical web member along the first direction when a lateral load greater than a preselected value is applied. 
   
     
     
         31 . The system of  claim 30 , wherein the lateral load greater than a preselected value is a seismic load. 
     
     
         32 . A staggered truss system, comprising:
 three or more trusses positioned in a staggered orientation, each truss including
 a top chord extending in a first direction; 
 a bottom chord spaced from the top chord and extending in parallel with the top chord; 
 at least one vertical web member positioned between the top and bottom chord; 
 at least one diagonal web member positioned between the top and bottom chord; and 
 at least one slip joint positioned at the interface of the top chord and the at least one vertical web member, the slip joint configured to connect the top chord to the at least one vertical web member while allowing slip between the top chord and the vertical web member along the first direction when a lateral load greater than a preselected value is applied. 
   
     
     
         33 . The system of  claim 32 , wherein the lateral load greater than a preselected value is a seismic load.