Steel-Cased Concrete Piers
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.
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 INVENTIONConcrete 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 INVENTIONIn 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
Referring to
As shown in
After tube 11 is positioned as shown in
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.
Referring to
In the embodiment of
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
After the concrete has hardened, the operator will attach a base 45 to tapered portion 41, as shown in
Referring to
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.
Type: Application
Filed: Jul 19, 2007
Publication Date: Jan 24, 2008
Inventor: Joy Henderson (Fort Worth, TX)
Application Number: 11/780,219
International Classification: E02D 5/44 (20060101);