Steel-Cased Concrete Piers

Abstract

A concrete pier and method of forming include providing a rust-resistant tube of a steel material. The tube is placed in a hole formed in the ground. The workers pour concrete into the tube and allow the concrete to harden. The above-ground structure is then attached to the upper end of the tube, leaving the tube in the ground to serve as a steel reinforcement for the concrete. The mounting structure at the upper end of the tube may be anchor bolts, or it may comprise tapered metal members. In the latter case, the above-ground structure to be supported by the pier has a base with a mating socket that fits over and is welded to the tapered mounting member.

Description

FIELD OF THE INVENTION

This invention relates in general to foundation piers, and in particular to a pier formed of concrete and encased within a steel tube.

BACKGROUND OF THE INVENTION

Concrete piers are widely used for supporting structures such as buildings, power transmission lines, light and sign poles, bridges, elevated transportation systems, as well as for underground reinforcements to hold back earth. Normally a pier is formed by drilling or forming a hole in the earth, which may be a mixture of rock and soil. The workers may set up a temporary tubular steel form and place the tubular form in the hole. Cardboard or paper temporary forms are alternatively placed within the hole.

Steel reinforcing bars are placed within the tubular forms. Typically, the reinforcing steel bars are spaced a selected distance, such as three inches, from the tubular form walls to minimize the danger of rusting caused by water penetration into the concrete. In some cases, temporary steel forms are also placed at the top of the steel forms within the hold to form an upper portion of the concrete into a shaped spud for supporting a hollow tapered steel column on the finished pier.

After the concrete has hardened sufficiently, the workers remove the temporary forms and put fill material around the concrete in a conventional manner. The above-ground structure will then be fastened to the top of the pier, such as by anchor bolts or the like.

Piers of this nature have a number of shortcomings. For example, it is time consuming to set up and remove the steel forms. Additionally, steel forms have to be carried to the work site and back. If paper forms are used, these must be transported to the work site and assembled. The pier is often larger in diameter than it needs to be, mainly because the reinforcing rods are placed three inches or more from their exterior surface of the concrete. Furthermore, after attaching the base of the above-ground structure, often a portion of the concrete is exposed. These exposed portions are porous, making it difficult to remove paint and other materials that may have been applied by vandals. Furthermore, exposed concrete above ground is easily damaged by impacts.

SUMMARY OF THE INVENTION

In this invention, a rust-resistant tube of a steel material is placed in the hole formed in the ground. The upper end of the tube will be typically protruding a short distance above the ground. The workers pour concrete into the tube and allow the concrete to harden. The workers fill any empty portions of an annulus surrounding the tube with a fill material, leaving the tube in place to service as reinforcing material for the concrete. The above-ground structure is attached to the upper end of the tube.

The tube is preferably hollow so that the flow of concrete from the open upper end to the bottom of the tube is unimpeded. The lower end of the tube is preferably open. The sidewall of the tube may be completely free of apertures. Alternately, a lower portion of the tube sidewall may have apertures for allowing concrete to flow into the annulus from the lower portion. If so, preferably the lower portion has a thicker cross-section than the impervious upper portion.

The mounting structure at the upper end of the tube is also preferably of steel. It may comprise conventional anchor bolts embedded in the concrete. It may also comprise a tapered mounting member protruding upward from the cylindrical portion of the tube. The tapered mounting member has a hole at its top through which the concrete is poured. The concrete is poured into the tube through the hole in the mounting member until the tube and the tapered mounting member are filled. The base of the above-ground structure to be supported by the pier preferably has a tapered socket in its interior that mates with the tapered exterior of the mounting member. When the base of the above-ground structure is placed on the mounting member, the exposed portion of the concrete at the upper end will be completely covered. The base of the above-ground structure may be welded to the tapered mounting member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a tube for a concrete pier constructed in accordance with this invention.

FIG. 2 is a sectional view of the tube of FIG. 1, shown installed within a hole in the earth, filled with concrete, and containing mounting members at its upper end.

FIG. 3 is a sectional view of an alternate embodiment of the tube of FIG. 1.

FIG. 4 is a sectional view of the tube of FIG. 3, shown installed within a hole in the earth.

FIG. 5 is an isometric view of another embodiment of the tube of FIG. 1.

FIG. 6 is an isometric view of the tube of FIG. 5, shown with a base of a mounting structure installed.

FIG. 7 is another isometric view of the tube of FIG. 5, but shown with a second embodiment of a base for an above-ground structure in the process of being lowered over the mounting member on the upper end of the tube.

FIG. 8 is an isometric view of the tube and base of FIG. 7, shown with the base installed and welded to the mounting member of the tube.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a tube 11 for a foundation pier is shown. Tube 11 is preferably cylindrical and formed of a high strength metal material that is resistant to rust. Preferably the material is steel, and preferably the steel is an alloy, such as stainless steel, that is resistant to rust. Tube 11 has a cylindrical sidewall 13, although other shapes are feasible. Tube 11 has an open upper end 15 and an open lower end 17. Tube 11 is preferably completely hollow prior to installation.

As shown in FIG. 2, a foundation pier is formed by first drilling or otherwise boring a hole 19 in the ground or earth 20. Earth 20 may be soil, rock, or a mixture of both. Hole 19 is normally cylindrical and of a somewhat larger diameter than tube 11. This results in an annulus 21 surrounding tube 11 when tube 11 is placed in hole 19. Hole 19 will normally have a depth that is less than the length of tube 13 so that a small portion of tube 11 protrudes above ground 20. The amount of protrusion will vary depending upon application, but the portion protruding above ground 20 will be substantially shorter than the portion of tube 11 located within hole 19. Tube 11 may rest on the bottom of hole 19, or spacers may be employed on the bottom of hole 19 if necessary.

After tube 11 is positioned as shown in FIG. 2, the workers will pour concrete 23 through open upper end 15. The concrete flows unimpeded to the lower end because there is no structure, such as steel reinforcing bars or the like, within tube 11. In the embodiment of FIG. 2, sidewall 13 is impervious to liquid, thus substantially all of the concrete 23 remains within tube 1. After pouring concrete 23, the workers fill annulus 21 in a conventional manner using any conventional fill material 27. Fill material 27 normally includes at least some of the earth that was excavated when forming hole 19.

In this embodiment, prior to concrete 23 hardening, the workers will position anchor bolts 25 at the upper end of tube 11. The lower portion of each anchor bolt 25 is embedded within concrete 23 while the upper portion protrudes above. Typically the upper portion of each anchor bolt 25 is threaded for attaching to a base of an above-ground structure.

FIG. 3 illustrates another embodiment, in which tube 29 has a sidewall that has a thickened lower portion 31 of greater thickness than its upper portion 35. A plurality of apertures 33 are formed in thickened portion 31. The thinner upper portion 35 of the sidewall above thickened portion 31 is free of any apertures.

Referring to FIG. 4, the pier using tube 29 of FIG. 3 is formed in the same manner as the embodiment of FIGS. 1 and 2. Some of the concrete 23 will flow out apertures 33 into annulus 21. The remaining portion of annulus 21 will be subsequently filled with fill material (not shown) in the same manner as fill material 27 of FIG. 2.

In the embodiment of FIG. 5, tube 37 has a cylindrical sidewall portion 39 and a tapered mounting portion 41 at its upper end. Tapered portion 41 is preferably conical and has a lesser length than cylindrical sidewall 39 of tube 37. Tapered portion 41 has an open upper end 42. Normally tapered portion 41 is formed separately from cylindrical portion 39 and secured as by a weld 43 to cylindrical portion 39.

Tube 37 is installed within a hole in the same manner as in the first two embodiments. The concrete is poured in open upper end 42. Sidewall 39 may optionally have a thickened portion with apertures as in the embodiment of FIGS. 3 and 4. Most, if not all of tapered portion 41 will protrude above the ground.

After the concrete has hardened, the operator will attach a base 45 to tapered portion 41, as shown in FIG. 6. Base 45 comprises a lower portion of the above-ground structure that will be supported by the pier. In the embodiment of FIG. 6, base 45 has a tapered exterior but it is polygonal, having four generally flat sides. Base 45 preferably has an interior socket 47 that is conical and formed at the same taper as tapered portion 41. Base socket 47 fits over tapered portion 41, for most, if not all of the length of tapered portion 41. Base 45 is attached to tapered portion 41 by a weld 49 in the preferred embodiment. The upper end of base 45 may be flat and conventional for attaching the above-ground structure, such as a light pole or sign post.

Referring to FIG. 7, an alternate embodiment of a base 51 serves as the lower end of an above-ground structure. Base 51 has a conical exterior that may be at the same taper angle as tapered portion 41. Conical base 51 has an interior socket 53 formed at the same taper as tapered portion 41. In FIG. 7, conical base 51 is shown being lowered over tapered portion 41 but not yet in its final position. In the final position of FIG. 8, lower end 55 of conical base 51 locates a short distance above weld 43. Preferably a weld 57 is made at lower end 55 to secure conical base 51 to tapered portion 41.

The invention has significant advantages. The strong non-rusting steel tube provides a more effective reinforcement for a concrete pier than one using reinforcing bars. This arrangement results in a stronger pier for the same pier diameter. The lack of any components that will rust, such as reinforcing bars, allows the pier to be of a smaller diameter than a pier with reinforcing bars. A smaller diameter pier allows the drilling of smaller diameter holes than for a reinforced concrete pier.

The use of a steel tube as the reinforcing member instead of conventional internal reinforcing bars, eliminates the labor of installing them. The use of a tube at the outer surface of the pier eliminates the labor costs of installing temporary paper or cardboard forms. The labor to assemble and the shipping costs of temporary forms are avoided by the use of the tube as a pier reinforcement.

The tube provides a pier with a smooth metal finish above-ground that is easier to clean. Columns or other above-ground structures may be easily mounted to the pier by welding or bolting to the pier mounting member. The tapered mounting extensions may be fabricated and welded to the cylindrical sidewalls of the tube at the factory, which avoids forming concrete spuds with temporary forms as in the prior art. The columns can be precisely mounted to the tapered mounting members without the use of anchor bolts, if desired.

Eliminating internal reinforcements removes obstacles to the free flow of concrete during pouring. Reinforcements can cause voids, requiring vibration members during the pouring process. In some of the embodiments, the tube has apertures to permit poured concrete to flow outward at the lower portion to fill part of the voids between the tube and the earth formation at the bottom of the drilled hole.

While the invention has been shown in only a few of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the invention.

Claims

1. A method of supporting a structure above ground, comprising: (a) placing a rust-resistant tube of a steel material in a hole formed in the ground; then (b) pouring concrete into the tube and allowing the concrete to harden; (c) filling any empty portions of an annulus surrounding the tube with a fill material; and (d) attaching a structure to an upper end of the tube.

2. The method according to claim 1, wherein the tube of step (a) is hollow so that the flow of concrete into the tube is unimpeded.

3. The method according to claim 1, wherein step (a) comprises providing the tube with an open lower end.

4. The method according to claim 1, wherein stop (a) comprises providing the tube with a sidewall having an upper portion that is free of any holes, preventing any concrete from flowing outward from the upper portion of the tube in stop (b).

5. The method according to claim 1, wherein: step (b) comprises embedding a lower portion of an anchor bolt within the concrete at the upper end of the tube prior to the concrete hardening; and step (d) comprises attaching the structure to the anchor bolt after the concrete has hardened.

6. The method according to claim 1, wherein: step (a) comprises providing the tube with a sidewall having a lower portion containing a plurality of apertures; and in step (b) some of the concrete flows out of the apertures of the tube into the annulus.

7. The method according to claim 1, wherein: step (a) comprises providing the tube with a tapered mounting section at its upper end and forming the hole to a depth such that the tapered mounting section protrudes from the hole; and step (b) comprises filling the tapered mounting section with concrete while filling the tube; and step (d) comprises providing the structure with a base with a tapered interior that mates with the tapered mounting section, placing the base of the structure over the tapered mounting section, then welding the base of the structure to the tapered mounting section.

8. The method according to claim 1, wherein step (a) comprises forming the hole to a depth such that when the tube is placed in the hole, the upper end of the tube protrudes above the ground.

9. A method of supporting a structure above ground, comprising: (a) providing a hollow tube with open upper and lower ends, the tube being of a rust-resistant steel material; (b) placing the tube in a hole formed in the ground to a depth such that the upper end of the tube protrudes from the hole; then (c) pouring concrete into the upper end the tube until the tube is substantially filled with concrete, then allowing the concrete to harden; (d) filling any empty portions of an annulus surrounding the tube with a fill material; and (e) mounting the structure to the upper end of the tube.

10. The method according to claim 9, wherein step (a) comprises providing the tube with a cylindrical sidewall having an upper portion that is free of any holes, preventing any concrete from flowing outward from the upper portion of the tube in step (c).

11. The method according to claim 9, wherein: step (c) comprises embedding a lower portion of an anchor bolt within the concrete at the upper end of the tube; and step (e) comprises attaching the structure to the anchor bolt after the concrete has hardened.

12. The method according to claim 9, wherein: step (a) comprises providing the tube with a sidewall having a lower portion of greater thickness than an upper portion, the lower portion having a plurality of apertures, the upper portion being free of apertures; and in step (c) some of the concrete flows out of the apertures of the tube into the annulus.

13. The method according to claim 9, wherein: step (a) comprises providing the tube with a tapered mounting section at its upper end, the tapered mounting section having a hole through which the concrete is poured in step (c); and step (c) comprises filling the tube with concrete by pouring concrete through the hole in the tapered mounting section until the tapered mounting section is filled with concrete; and step (d) comprises providing the structure with a base with a tapered interior that mates with the tapered mounting section, placing the base of the structure over the tapered mounting section, then welding the base of the structure to the tapered mounting section.

14. The method according to claim 13, wherein the tapered mounting section is conical and the portion of the tube below the tapered mounting section is cylindrical.

15. A foundation pier, comprising: a rust-resistant tube of a steel material located in a hole formed in the earth, defining an annulus surrounding the tube; the tube being substantially filled with concrete; at least part of the annulus surrounding the tube being filled with an earthen fill material; a metal mounting member at an upper end of the tube; a base for an above-ground structure connected to the mounting member for supporting the above-ground structure above the tube.

16. The pier according to claim 15, wherein the interior of the tube is free of any reinforcing metal for the concrete.

17. The pier according to claim 15, wherein the tube has a lower portion with a thickened sidewall containing a plurality of apertures and an upper portion that is free of apertures and has a thinner sidewall.

18. The pier according to claim 15, wherein: the mounting member comprises an anchor bolt having a lower portion embedded within the concrete and an upper portion secured to the base of the above-ground structure.

19. The pier according to claim 1, wherein: step (a) comprises providing the tube with a sidewall having a lower portion containing a plurality of holes; and in step (b) some of the concrete flows out of the apertures of the tube into the annulus.

20. The pier according to claim 15, wherein: the mounting member on the tube comprises a tapered mounting section that is filled with concrete and protrudes from the hole; and the base of the above-ground structure has a tapered socket that mates with the tapered mounting section and covers any exposed concrete, the base being welded to the tapered mounting section.