Shear dowel assembly

Abstract

This invention relates to a shear dowel assembly for distributing loads between adjacent concrete slabs, separated by a joint. The shear dowel assembly includes a dowel sheath having a front face and a rear face. The rear face of the dowel sheath is imbedded within the first concrete slab, whereas the front face is left substantially flush with the side of said first concrete slab. The front face also has a portion defining an opening therein. There is also provided a shear dowel adapted to be inserted into the opening in the dowel sheath, with a first end of the shear dowel abutting the rear face of the dowel sheath, and a second end of the shear dowel extending out from the opening in the dowel sheath, whereby the shear dowel may be embedded within a second adjacent concrete slab to be poured. The shear dowel has a width of constant cross section, and is preferably trapezoidal (or in the shape of a trapezium) in plan view. The shear dowel assembly allows for increased differential movement of the adjacent concrete slabs, as the joint gap between the concrete slabs increases, whilst retaining the load carrying capacity of the shear dowel at all times.

1 - 13 . (canceled) 
   
   
       14 . A shear dowel assembly for distributing loads between adjacent concrete slabs, separated by a joint, said shear dowel assembly comprising:
 a dowel sheath adapted to be embedded into a side of a first concrete slab,   said dowel sheath having a front face and a rear face, with the rear face being embedded within said first concrete slab, and the front face being substantially flush with the side of said first concrete slab, and   said front face having a portion defining an opening in the side of said first concrete slab,   said dowel sheath having tapering sides which are not parallel in relation to an axis perpendicular to the joint between the adjacent concrete slabs, and   wherein a width of the dowel sheath at the rear face is less than a width of the dowel sheath at the front face; and   a shear dowel having a substantially rectangular outline in plan view,   the shear dowel having a width of constant cross section and a length extending perpendicular to the joint,   the shear dowel adapted to be inserted into the opening in the dowel sheath, with a first end of the shear dowel abutting the rear face of the dowel sheath, and a second end of the shear dowel extending out from the opening in the dowel sheath, wherein the shear dowel is embeddable within a second adjacent concrete slab to be poured,   the dowel sheath and shear dowel allowing for increased differential movement of the adjacent concrete slabs while continuing to effectively distribute the loads between the adjacent slabs through the shear dowel as the width of the joint between the concrete slabs increases.   
   
   
       15 . A shear dowel assembly, as claimed in  claim 14 , wherein a longer axis of the rectangular shear dowel is extended perpendicular to the joint and a shorter axis of the shear dowel is parallel to the joint. 
   
   
       16 . A shear dowel assembly, as claimed in  claim 14 , wherein there is a gap of at least ¼ inch between the sides of the shear dowel and the tapered sides of the dowel sheath at the region where the shear dowel abuts the rear face of the dowel sheath, once the shear dowel has been inserted in the dowel sheath. 
   
   
       17 . A shear dowel assembly as claimed in  claim 14 , wherein there is a gap of at least 1 inch between the sides of the shear dowel, and the tapered sides of the dowel sheath at the region where the sides of the dowel sheath meet the front face of the dowel sheath, once the shear dowel has been inserted in the dowel sheath. 
   
   
       18 . A shear dowel assembly, as claimed in  claim 14 , wherein the dowel sheath is substantially trapezoidal in plan view. 
   
   
       19 . A shear dowel assembly, as claimed in  claim 14 , wherein the dowel sheath is in substantially the shape of a trapezium, in plan view. 
   
   
       20 . A shear dowel assembly, as claimed in  claim 14 , wherein the inside of the dowel sheath is provided with at least two pairs of positioning means to contact the sides of the shear dowel and thereby to at least one of guide and retain the shear dowel in position within the dowel sheath until differential movement occurs across the joint, when the position means may snap off. 
   
   
       21 . A shear dowel assembly as claimed in  claim 14 , wherein the shear dowel is made of mild steel plate. 
   
   
       22 . A shear dowel assembly, as claimed in  claim 14 , wherein the dowel sheath is made from a plastics material. 
   
   
       23 . A shear dowel assembly, as claimed in  claim 14 , wherein said shear dowel has a dimension perpendicular to the joint which is greater than a dimension parallel to the joint. 
   
   
       24 . A shear dowel assembly for distributing loads between adjacent concrete slabs, said shear dowel assembly comprising:
 a dowel sheath, said dowel sheath having a front face and a rear face, with the front face defining an opening in the dowel sheath,   said dowel sheath having tapering sides wherein the width of the dowel sheath at the rear face is less than the width of the dowel sheath at the front face; and   a shear dowel adapted to be inserted into the opening in the dowel sheath, with a first end of the shear dowel abutting the rear face of the dowel sheath, and a second end of the shear dowel extending out from the opening in the dowel sheath, and said shear dowel having a width of constant cross section.   
   
   
       25 . A shear dowel assembly, as claimed in  claim 24 , wherein said shear dowel has a dimension perpendicular to the joint which is greater than a dimension parallel to the joint. 
   
   
       26 . A method of allowing for effective load transfer between adjacent concrete slabs separated by a joint, said method utilising the shear dowel assembly, and said method comprising the steps of:
 with an a assembly comprising a dowel sheath and a shear dowel, the dowel sheath adapted to be embedded into a side of a first concrete slab, said dowel sheath having a front face and a rear face, with the rear face being embedded within said first concrete slab, and the front face being substantially flush with the side of said first concrete slab, and said front face having a portion defining an opening in the side of said first concrete slab, said dowel sheath having tapering sides which are not parallel in relation to an axis perpendicular to the joint between the adjacent concrete slabs, and wherein a width of the dowel sheath at the rear face is less than a width of the dowel sheath at the front face; and the shear dowel having a substantially rectangular outline in plan view, the shear dowel having a width of constant cross section and a length extending perpendicular to the joint, the shear dowel adapted to be inserted into the opening in the dowel sheath, with a first end of the shear dowel abutting the rear face of the dowel sheath, and a second end of the shear dowel extending out from the opening in the dowel sheath, wherein the shear dowel is embeddable within a second adjacent concrete slab to be poured, the dowel sheath and shear dowel allowing for increased differential movement of the adjacent concrete slabs while continuing to effectively distribute the loads between the adjacent slabs through the shear dowel as the width of the joint between the concrete slabs increases
 embedding the dowel sheath into the first concrete slab to be poured; 
 inserting the shear dowel into the opening in the dowel sheath; and 
 pouring the second concrete slab adjacent the first concrete slab, wherein the shear dowel is encased in said second concrete slab, 
   the arrangement and construction being such that the shear dowel assembly allows for increased differential movement of the adjacent concrete slabs as the joint gap between the concrete slabs increases.   
   
   
       27 . A method, as claimed in  claim 26 , wherein said shear dowel is placed with a dimension perpendicular to the joint which is greater than a dimension parallel to the joint.