Hollow, composite dowel bar assemblies, associated fabrication methodology, and apparatus

Abstract

Hollow composite dowel bar assemblies, their manufacture, and apparatus for manufacture. The dowel bar assemblies may include an elongate and hollow core, a protective jacket coating at least the sidewall exterior of the core, and a sealing structure coupled with each end of the combined core and jacket, that are configured to protect the core from the environment.

1 . A dowel bar assembly, comprising:
 an elongate hollow core;   a protective jacket coating at least a sidewall exterior of the core, and having a bond breaker exterior; and   a sealing structure coupled with each end of the combined core and jacket, wherein the sealing structures are configured to protect the core.   
     
     
         2 . The dowel bar assembly of  claim 1 , wherein the core includes a tube having a cross-section that is circular, elliptical, or oval. 
     
     
         3 . The dowel bar assembly of  claim 1 , wherein the core is a hollow cylinder. 
     
     
         4 . The dowel bar assembly of  claim 1 , wherein the core is selected to have a high load transfer efficiency. 
     
     
         5 . The dowel bar assembly of  claim 1 , wherein the core is structural steel. 
     
     
         6 . The dowel bar assembly of  claim 1 , wherein the protective jacket is configured to serve as a bond breaker coating for the dowel bar assembly. 
     
     
         7 . The dowel bar assembly of  claim 1 , wherein the protective jacket includes a plastic resin. 
     
     
         8 . The dowel bar assembly of  claim 7 , wherein the plastic resin is reinforced by one or more reinforcing fibers. 
     
     
         9 . The dowel bar assembly of  claim 1 , wherein the protective jacket includes a fiber-reinforced plastic resin having multiple layers of reinforcing fibers. 
     
     
         10 . A method of manufacturing a dowel bar, comprising:
 preparing an elongate hollow core precursor;   coating at least a sidewall exterior of the core precursor with a protective jacket;   cross-cutting the jacketed core precursor into segments having a desired length; and   capping each end of the core segments with a sealing structure.   
     
     
         11 . The method of  claim 10 , wherein preparing the elongate hollow core precursor includes preparing a core precursor having a cross-section that is circular, elliptical, or oval. 
     
     
         12 . The method of  claim 10 , wherein the core precursor includes a hollow cylinder. 
     
     
         13 . The method of  claim 10 , wherein coating the core precursor with a protective jacket includes pultrusion-forming a fiber-reinforced plastic-resin sleeve continuously and bondedly around the core precursor to form a coated core precursor. 
     
     
         14 . The method of  claim 13 , wherein pultrusion-forming the fiber-reinforced plastic-resin sleeve includes continuous dispensing of a reinforcing fiber; applying a curable plastic resin to the reinforcing fiber, and guiding the resin-soaked fibers into a circumferential layer structure circumsurroundingly disposed onto an outside surface of the core precursor. 
     
     
         15 . The method of  claim 14 , wherein pultrusion-forming the fiber-reinforced plastic-resin sleeve includes guiding the resin-soaked fibers into a circumferential layer structure having the fibers oriented at an off-axis angle relative to a longitudinal axis of the core precursor. 
     
     
         16 . The method of  claim 13 , wherein preparing the core precursor includes longitudinally alternating a plurality of core segments with end-plug blanks having an outside diameter substantially equal to the outside diameter of the core segments; and
 cross-cutting the jacketed core precursor includes sawing across the end-plug blanks so that each jacketed core segment is effectively capped.   
     
     
         17 . The method of  claim 13 , wherein the core precursor includes a longitudinally extended core precursor;
 cross-cutting the jacketed core precursor includes sawing through the jacketed extended core precursor to yield jacketed core segments; and   capping each end of the jacketed core segments includes inserting a protective end cap into each end of the jacketed core segment.   
     
     
         18 . An apparatus for forming elongate hollow dowel bar assemblies; comprising
 an advancing mechanism configured to advance an extended hollow core precursor;   a core heater, configured to receive and heat the core precursor;   a jacket applicator, configured to apply reinforcing fibers and a curable resin to an exterior of the core precursor;   a curing apparatus, configured to cure the curable resin;   a pultrusion puller, configured to pull the coated core precursor through the curing apparatus to produce a jacketed core precursor; and   a crosscutting mechanism configured to cut the jacketed core precursor into segments having a desired length.   
     
     
         19 . The apparatus of  claim 18 , wherein the curing apparatus includes a heated pultrusion die, configured to receive the fiber- and resin-coated core precursor and cure the curable resin. 
     
     
         20 . The apparatus of  claim 18 , wherein the curing apparatus includes a curing oven, configured to receive the fiber- and resin-coated core precursor and cure the curable resin.