Flange Connectors for Double Tee Beams

Abstract

A connector for joining concrete structures such as double tee beams to one another. The connector includes a curved bolt that is formed with a shape memory alloy. Through utilization of the bolt, a joint can be post-tensioned following assembly through application of heat to the joint. Post-tensioning can be re-applied following loosening of the joint through application of heat. When considering a super elastic shape memory alloy, the bolt can be a smart bolt that can self-correct following deformation due to excessive load.

What is claimed is: 
     
         1 . A connector for a reinforced concrete slab comprising a bolt, the bolt including a first end and a second opposite end and defining a curvature between the first end and the second end, the bolt comprising a shape memory alloy. 
     
     
         2 . The connector of  claim 1 , wherein the shape memory alloy is a super elastic shape memory alloy. 
     
     
         3 . The connector of  claim 1 , wherein the shape memory alloy is a nickel titanium alloy. 
     
     
         4 . The connector of  claim 1 , wherein the bolt comprises multiple rods, each rod comprising the shape memory alloy. 
     
     
         5 . The connector of  claim 1 , wherein the connector further comprises a duct that is cast into the reinforced concrete slab. 
     
     
         6 . A method for forming a joint between a first reinforced concrete slab and a second reinforced concrete slab, comprising:
 retaining a first portion of a bolt within a first duct located within the first concrete slab, the bolt comprising a shape memory alloy and defining a curvature between a first end of the bolt and a second end of the bolt;   retaining a second portion of the bolt within a second duct located within the second concrete slab;   following, heating the bolt to a temperature that is about 5° C. less than the upper temperature of the transition temperature range of the shape memory alloy or greater.   
     
     
         7 . The method of  claim 6 , wherein at least one of the first concrete slab and the second concrete slab is a double tee beam. 
     
     
         8 . The method of  claim 6 , wherein both the first concrete slab and the second concrete slab are double tee beams, the joint being formed between flanges of the first double tee beam and the second double tee beam. 
     
     
         9 . The method of  claim 6 , wherein the shape memory alloy is a nickel titanium alloy. 
     
     
         10 . The method of  claim 6 , wherein the shape memory alloy is a super elastic shape memory alloy. 
     
     
         11 . The method of  claim 6 , further comprising pre-straining the bolt prior to retaining the first and second portions within the first and second ducts, respectively. 
     
     
         12 . A method for reapplying a post-tensioning force to a joint, the joint being formed between a first concrete slab and a second concrete slab, the joint comprising a connector, the connector including a curved bolt that includes a shape memory alloy, the method including heating the bolt to a temperature that is about 5° C. less than the upper temperature of the transition temperature range of the shape memory alloy or greater. 
     
     
         13 . The method of  claim 12 , wherein at least one of the first concrete slab and the second concrete slab is a double tee beam. 
     
     
         14 . The method of  claim 13 , wherein both the first concrete slab and the second concrete slab are double tee beams, the joint being formed between flanges of the first double tee beam and the second double tee beam. 
     
     
         15 . The method of  claim 12 , wherein the shape memory alloy is a nickel titanium alloy. 
     
     
         16 . The method of  claim 12 , wherein the shape memory alloy is a super elastic shape memory alloy.