Collapsible expansion joint

Abstract

An elongated joint connects adjacent concrete sections, usually slabs, and remains below the top surface of the slabs during temperature fluctuations. The joint has a grooved top surface and an opposite keyed bottom, and two mirror image spaced apart sides. The top, bottom, and sides form a generally rectangular cross section. Within the joint, upright risers, flat braces, and angled knees provide stiffness to the joint yet allow bending to withstand expansion and contraction of adjacent slabs. The joint has a generally symmetrical cross section. Upon the sides and bottom, the joint has keys that connect the joint to adjacent slabs. The joint can also serve as formwork for concrete.

1 . A device filling the gap between adjacent concrete sections, such as slabs and walls, that expand and contract, comprising:
 a hollow, elongated joint having a generally rectangular cross section, keys adapted to engage said concrete sections, and a plurality of integral internal members within the cross section forming a web stiffening said joint for vertical and horizontal loads.   
   
   
       2 . The gap filling device of  claim 1  further comprising:
 said joint having a top, a spaced apart opposite bottom, and two spaced apart sides connecting said top and said bottom, said top having two halves connecting at a groove lengthwise upon said joint, said bottom having a raised key, and each of said sides having a key extending into said joint.   
   
   
       3 . The gap filling device of  claim 2  further comprising:
 said bottom having two outer sections;   said raised key having a convex shape extending towards the center of said joint and locating between said outer sections that adjoin said sides; and,   said keys having a concave shape extending towards the center of said joint, and generally locating in the center of each of said sides between two outer sections that adjoin said top and said bottom respectively.   
   
   
       4 . The gap filling device of  claim 1  further comprising:
 said internal members including at least one riser extending upwards from said bottom, at least one brace extending inwards from each of said sides, at least one knee brace orienting an angle and connecting to said top and at least one of said internal members; and,   said internal members supporting loads applied to said joint.   
   
   
       5 . The gap filling device of  claim 4  further comprising:
 two first risers extending upwards from said bottom, two first braces extending inwards from said keys and connecting to said first risers, two second risers extending collinear from said first risers, two second braces extending inwards from said sides generally above said first braces and parallel to said first braces and connecting to said second risers, two first knee braces extending from said top to said side at an angle and connecting to said second brace proximate said side, two second knee braces, generally parallel to said first knee braces and connecting to said second brace and said second riser, and a third riser generally vertical and connecting to said second knee braces and below said top proximate the center.   
   
   
       6 . The gap filling device of  claim 5  wherein said joint is symmetric. 
   
   
       7 . The gap filling device of  claim 2  further comprising:
 said bottom having two outer sections;   said raised key having a chevron like shape extending towards the center of said joint and locating between said outer sections that adjoin said sides; and,   said keys having a concave shape extending towards the center of said joint, and generally locating in the center of each of said sides between two outer sections that adjoin said top and said bottom respectively.