Sleeve Device For Transferring Bending Moments

Abstract

A sleeve device for transferring bending moments induced in a reinforced concrete slab includes a generally hollow member and tension rebars. The hollow member is positioned and fastened on a bottom formwork defining the reinforced concrete slab. The tension rebars are connected to opposing sides of an upper portion of the hollow member either directly or using rebar connectors. The hollow member creates a void in the reinforced concrete slab by pouring of concrete around an outer wall of the hollow member. The hollow member transfers compressive stresses across a bottom of the hollow member and tensile stresses through the tension rebars and the upper portion of the hollow member. The affixed tension rebars are spliced with regular reinforced concrete slab rebars to develop tensile stresses that are transferred through the relatively stiffer hollow member to retain a slab moment capacity.

I claim: 
     
         1 . A sleeve device for transferring bending moments induced in a reinforced concrete slab, said sleeve device comprising:
 a generally hollow member positioned on and fastened to a bottom formwork defining said reinforced concrete slab, said generally hollow member configured to create a void in said reinforced concrete slab by pouring of concrete around an outer wall of said generally hollow member, said generally hollow member further configured to transfer compressive stresses across a bottom of said generally hollow member and tensile stresses through tension rebars and an upper portion of said generally hollow member; and   said tension rebars connected to opposing sides of said upper portion of said generally hollow member, said tension rebars are configured to be spliced with top rebars of said reinforced concrete slab in accordance with a rebar tension splice length for transferring said bending moments induced in said reinforced concrete slab, wherein said bending moments in said reinforced concrete slab are resisted by said tensile stresses in said tension rebars and said compressive stresses in said concrete, and wherein said tensile stresses in said tension rebars on said opposing sides of said generally hollow member are transferred into said generally hollow member, and said tensile stresses acting on said opposing sides of said generally hollow member are balanced out through said outer wall of said generally hollow member, thereby bridging said tensile stresses from said tension rebars.   
     
     
         2 . The sleeve device of  claim 1 , wherein said tension rebars are welded directly to said opposing sides of said upper portion of said generally hollow member, wherein said tension rebars are configured to directly transfer said tensile stresses to and from said generally hollow member. 
     
     
         3 . The sleeve device of  claim 1 , further comprising rebar connectors operably connected on said opposing sides of said upper portion of said generally hollow member, wherein said rebar connectors are configured to fixedly connect said tension rebars to said opposing sides of said upper portion of said generally hollow member. 
     
     
         4 . The sleeve device of  claim 1 , wherein a cross section of said generally hollow member is of a geometric shape comprising at least one of a circular shape, a square shape, and a rectangular shape. 
     
     
         5 . The sleeve device of  claim 1 , wherein said generally hollow member is of a generally cylindrical shape. 
     
     
         6 . The sleeve device of  claim 1 , wherein said tension rebars are further configured to be rotated and repositioned to transfer said tensile stresses to and from said tension rebars and said generally hollow member in a plurality of directions. 
     
     
         7 . The sleeve device of  claim 1 , wherein said tension rebars are configured as deformed rebars to be fixedly connected to said opposing sides of said upper portion of said generally hollow member to transfer said tensile stresses to and from said generally hollow member. 
     
     
         8 . The sleeve device of  claim 1 , wherein said tension rebars are configured as corrugated fins to be fixedly connected to said opposing sides of said upper portion of said generally hollow member to transfer said tensile stresses to and from said generally hollow member. 
     
     
         9 . The sleeve device of  claim 1 , wherein said tension rebars are configured as bent plates to be fixedly connected to said opposing sides of said upper portion of said generally hollow member to transfer said tensile stresses to and from said generally hollow member. 
     
     
         10 . A method for transferring bending moments induced in a reinforced concrete slab, said method comprising:
 providing a sleeve device comprising:
 a generally hollow member positioned on and fastened to a bottom formwork defining said reinforced concrete slab; and 
 tension rebars connected to opposing sides of an upper portion of said generally hollow member; 
   splicing said tension rebars of said sleeve device with top rebars of said reinforced concrete slab in accordance with a rebar tension splice length for transferring said bending moments induced in said reinforced concrete slab;   creating a void in said reinforced concrete slab by said generally hollow member of said sleeve device by pouring concrete around an outer wall of said generally hollow member;   transferring tensile stresses due to said bending moments induced in said reinforced concrete slab to a first of said tension rebars on one of said opposing sides of said generally hollow member and said upper portion of said generally hollow member;   transferring said transferred tensile stresses from said upper portion of said generally hollow member to a second of said tension rebars on another one of said opposing sides of said generally hollow member; and   transferring said transferred tensile stresses from said second of said tension rebars to said top rebars of said reinforced concrete slab spliced with said tension rebars, wherein said bending moments in said reinforced concrete slab are resisted by said tensile stresses in said tension rebars and compressive stresses in said concrete, and wherein said tensile stresses in said tension rebars on said opposing sides of said generally hollow member being transferred into said generally hollow member, and said tensile stresses acting on said opposing sides of said generally hollow member are balanced out through said outer wall of said generally hollow member, thereby bridging said tensile stresses from said tension rebars.   
     
     
         11 . The method of  claim 10 , wherein said tension rebars are welded directly to said opposing sides of said upper portion of said generally hollow member to directly transfer said tensile stresses to and from said generally hollow member. 
     
     
         12 . The method of  claim 10 , wherein said tension rebars are fixedly connected to said opposing sides of said upper portion of said generally hollow member using rebar connectors operably connected on said opposing sides of said upper portion of said generally hollow member. 
     
     
         13 . The method of  claim 10 , further comprising coupling said tension rebars to said reinforced concrete slab rebars via horizontal splicing for transferring said bending moments induced in said reinforced concrete slab. 
     
     
         14 . The method of  claim 10 , wherein a cross section of said generally hollow member of said sleeve device is of a geometric shape comprising at least one of a circular shape, a square shape, and a rectangular shape. 
     
     
         15 . The method of  claim 10 , wherein said generally hollow member is of a generally cylindrical shape. 
     
     
         16 . The method of  claim 10 , further comprising rotating and repositioning said tension rebars to transfer said tensile stresses to and from said tension rebars and said generally hollow member in a plurality of directions. 
     
     
         17 . The method of  claim 10 , wherein said tension rebars are configured as one of deformed rebars, corrugated fins, and bent plates to be fixedly connected to said opposing sides of said upper portion of said generally hollow member to transfer said tensile stresses to and from said generally hollow member.