Reinforced concrete structure, rebar end anchor therefor and method of manufacturing

Abstract

A method of forming anchors at the ends of rebars includes providing an anchor plate, forming an opening through the anchor plate that is larger than the diameter of the rebar, heating the end of a rebar, inserting it into the anchor plate opening and then forging it to upsize the rebar end into engagement with the wall of the anchor plate opening. Preferably, the wall of the opening through the anchor plate is irregular to enhance the interlock between the upsized rebar end and the anchor plate. The resulting rebar end anchor then finds particular utility in reinforced concrete structure at joint intersections of for example, a beam and column or wall.

Description

FIELD OF THE INVENTION Background of the Invention [0001] Concrete is characterized by high compressive strength and notoriously poor tensile strength. In a typical reinforced concrete structure this deficiency in the tensile strength of the concrete is obviated by imbedding in the concrete at those points where tensile stress will be encountered, reinforcing bars, typically of steel. Where a section of a reinforced concrete structure terminates at another section, such as at a beam / wall or beam / column intersection, provision must also be made to insure that the ends of the rebars will not pull out of the wall or column when tensile stress is encountered. Conventionally, this was remedied by bending the end of the rebar and perhaps inserting another rebar beneath the bend perpendicularly to the length of the first rebar. Typically, a joint of this type is congested to begin with and this remedy compounded the congestion, resulting in higher concrete placement costs and possible conc...

AI Technical Summary

Benefits of technology

"The present invention provides a method of manufacturing an end anchor with superior structural performance but at a lower cost than conventional methods. This is achieved by using a separate anchor plate with an opening having irregular wall portions, through which a smaller forging press can insert the end of rebar and forge it onto the plate to form a mechanical interlock. This method requires less energy, time, and expense than conventional methods and allows for the construction of intersecting joints without adding to the congestion. The forging process also provides a stronger section of rebar at the connection, ensuring failure to occur away from the connection."

Problems solved by technology

Concrete is characterized by high compressive strength and notoriously poor tensile strength.

Typically, a joint of this type is congested to begin with and this remedy compounded the congestion, resulting in higher concrete placement costs and possible concrete consolidation problems.

Where the rebar ends are provided with a forged head, a very large forging press is required, a substantial portion of the rebar must be preheated for forging with a commensurate expenditure of time and energy, and multiple strikes of the press are required to create the headed end.

If the rebar were threaded without upsizing the end, the thread would create a weak point that would reduce the overall tensile strength of the rebar.

This approach has the drawbacks of requiring a separate fabricated anchor plate and requiring the upsizing of the rebar end prior to welding, but more importantly, the welding process is subject to various process variables that contribute to quality considerations.

Images