Tetrahedral Tube Reinforcement of Concrete

Abstract

A weight reduced and strength enhanced concrete structure in which at least one tubular reinforcing core is embedded in a solid concrete matrix. Each core is a chain of integrally interconnected hollow tetrahedra. Each tetrahedra has triangular faces connected at common edges and vertices. The planar faces of adjacent tetrahedra are spaced from each other, and concrete fills the spaces. The cores are suspended within the concrete and self-anchored, without anchors at the exterior surface of the structure. With the embedded cores the concrete structure becomes more resistant to compressive, tensile, and bending loads. For even greater strength of the structure, the cores can be tensioned and thereby pre-stress the concrete. Impact or other loads are distributed substantially isotropically, thereby reducing local stresses. These advantages can be achieved with cores that are lighter than the concrete material they displace or rebar they replace.

1 . A weight reduced and strength enhanced concrete structure comprising a continuous matrix of concrete reinforced with at least one tubular chain of integrally connected hollow tetrahedra. 
     
     
         2 . The concrete structure of  claim 1 , wherein a plurality of said chains are independently embedded and self-anchored in the matrix. 
     
     
         3 . The concrete structure of  claim 2 , wherein each chain is in tension, thereby pre-stressing the concrete structure. 
     
     
         4 . A reinforced structural member comprising:
 a body of rigid matrix material, having a length and width;   at least one reinforcing core embedded in the matrix, having a chain of integrally connected hollow tetrahedra, each tetrahedron defining four triangular planes with each plane in intimate contact with matrix material, thereby locking the reinforcing core in fixed relation to the matrix material.   
     
     
         5 . The structural member of  claim 4 , wherein the member is a beam having a longitudinal centerline and the at least one reinforcing core extends along the length of the beam parallel to and offset from the centerline. 
     
     
         6 . The structural member of  claim 5 , wherein
 the beam centerline extends horizontally;   the beam has longitudinal ends that are both anchored; and   the at least one reinforcing core is vertically below the centerline.   
     
     
         7 . The structural member of  claim 5 , wherein
 the beam centerline extends horizontally;   the beam has longitudinal ends, and is anchored only at one end with a cantilevered other end; and   the at least one reinforcing core is vertically above the centerline.   
     
     
         8 . The structural member of  claim 4 , comprising
 a rectangular slab anchored on at least two sides, and having a center plane between upper and lower surfaces; and   a plurality of reinforcing cores extending through the matrix below the center plane.   
     
     
         9 . The structural member of  claim 8 , wherein
 a first plurality of laterally spaced apart reinforcing cores extend parallel to the length of the slab below the center plane; and   a second plurality of laterally spaced apart reinforcing cores extend parallel to the width below the center plane.   
     
     
         10 . The structural member of  claim 4 , wherein each reinforcing core is in tension and thereby longitudinally pre-compresses adjacent matrix material, whereby when the structural member bears no external load, the faces on the tetrahedra apply a compression force on the matrix material that is in intimate contact therewith. 
     
     
         11 . The structural member of  claim 4 , wherein the matrix is concrete. 
     
     
         12 . The structural member of  claim 4 , wherein the matrix is plastic foam. 
     
     
         13 . The structural member of  claim 5 , wherein the matrix is concrete. 
     
     
         14 . The structural member of  claim 11 , wherein a plurality of parallel, spaced apart and unconnected cores extend longitudinally and entirely within the structural member. 
     
     
         15 . The structural member of  claim 11 , wherein each core includes means for rigidly tying the apices of successive tetrahedra in said chains. 
     
     
         16 . The structural member of  claim 15 , wherein
 the cores are embedded in a beam that extends in a longitudinal direction;   the edges of successive tetrahedra are connected by a rigid web; and   all the webs of the cores are oriented obliquely when viewed in cross section to said longitudinal direction.   
     
     
         17 . The structural member of  claim 11 , wherein the member is a horizontally extending concrete beam having a horizontally extending centerline, and all of said reinforcing cores are embedded in the concrete parallel to and vertically offset from the centerline. 
     
     
         18 . A reinforced concrete beam or slab having a length and width, comprising: a plurality of elongated metal reinforcing cores embedded in a concrete matrix, each core having a chain of integrally connected hollow tetrahedra, each tetrahedron defining four triangular planes with each plane in intimate contact with matrix material, thereby locking each reinforcing core in fixed relation to the matrix material. 
     
     
         19 . The reinforced concrete beam or slab of  claim 18 , wherein at least some of said plurality of cores are rigidly secured together in a side-by-side parallel array, 
     
     
         20 . The reinforced concrete beam or slab of  claim 18 , constituting a building element subject to a bending load transverse to the length or width.