US3145540A - Prestressed composite pile - Google Patents

Description

25, 1954 J. R. BAITTINGER 3,145,540

PRESTRESSED COMPOSITE PILE Filed March 14, 1962 2 Sheets-Sheet 1 INVENTOR. JHCK R, 5F TT/N GER HTT RNEY g- 1964 J. R. BAITTINGER PRESTRESSED COMPOSITE FILE 2 Sheets-Sheet 2 Filed March 14, 1962 INVENTOR. JqcK R, 517/ TTINCiER HTTORNEY tables.

United States Patent 3,145,540 PRESTRESEEED COMPGSTTE PTLE Jack R. Baittinger, 2 Wheatley tCourt, Scotch Plains, N.J., assignor of one-half to John J. Daugherty, Cedar Grove, NJ.

Filed Mar. 14, 1 .962, Ser. No. 179,7(39 ltila-im. {Cl. 61-53} This invention relates generally to the art of piling and more particularly to an improved composite pile, the upper part of which comprises prestressed reenforced concrete and the lower part comprises wood.

Piles are used to support or to form foundations for structures such as buildings, tanks, bridges, conduits, piers, wharves, etc. by inserting them into or through the yielding surface strata far enough to obtain a solid support for the principal structure.

As is well known, untreated wooden piles are frequently unsatisfactory when exposed to salt or brakish water, or when exposed to changing tides or changing water In free Water such piles are attacked by marine borers and other insects and are liable to rot. In earth above the lowest level of the water table, they are subject to termites, fungi, mold and rot. Because concrete is not unduly alfected by the above destructive forces, it has been proposed to use-a composite wood-concrete pile structure having a wooden section entirely below the area where the above destructive forces attack and a concrete section connected to the top of the wooden section.

Composite piles wherein the upper part is formed of hollowcylindrical concretesectionsconnected by a solid concrete section and fastened together with prestressed steel cables and reenforced by longitudinal and helical wires are desirable as the hollow upper parts of the composite pile provide great point-bearing area and large surface area per-unit weight-of material. The upper part also has a large section modulus, resulting in a high bending resistance. This results in a rigid pile, well able to resist horizontal forces suchas winds, waves, earthquakes and the impact of ships. Such hollow 'upper part of the pile also has a large radius ofgyration in proportion to its weight so that its slenderness ratio is low when column action must be taken into account in the design.

It is accordingly a principal object of'the present invention to provide a composite pile based on the use of a prestressed concrete hollow cylindrical upper section and a wooden bottom section.

Another object of the invention is to provide a composite pile that is especially well adapted to withstand both tensional and compressional longitudinal forces as well as lateral stresses.

The above advantages and objects are achieved by providing a composite pile that is economical in use and which does not require expensive or scarce speciallyfabricated parts.

For further comprehension of the invention and of the objects and advantages thereof, reference will be had to the following description and accompanying drawings and to the appended claim in which the various novel features of the invention are most particularly set forth.

In the accompanying drawings forming a material part of this disclosure:

FIG. 1 is a side elevational view of a composite pile embodying my invention, only part of the bottom section being shown.

FIG. 2 is a cross-sectional View taken on the line 2-2 of FIG. 3.

FIG. 3 is a top plan view as seen from the line 33 of FIG. 1.

FIG. 4- is a cross-sectional view taken on the line 44 of FIG. 1.

3,145,546 Patented Aug. 25, 1964 FIG. 5 is a similar view taken on the line 5-5 of FIG. 1.

FIG. 6 is atop perspective view of a reenforcingcage.

FIG. 7 is an enlarged cross-sectional view taken on the line 77 of FIG. 2.

Referring in detail to the drawings, vin FIG. 1,.a composite pile embodying my invention is shown and designated generally by the reference numeral 19. The composite pile as can be seen in FIGS. land '2 comprises two principal parts, a wooden lower section 12 (the lower part of which is not shown) and an upper concrete section-14.

Thewooden section 12 ordinarily will be generally round in cross-section, such as a section of log, although unlike other known structures the cross-sectional shape of the wooden section is not of particular importance, but its top or butt end 12a must'be round, the only requirement being that the dimension and cross-section of this end portion be such as to provide a tight fit in the bottom of theconcrete section 14.

The upper section 14.of the composite pile '10 isa precast prestressed .cylindrical concrete body formed of three sections, a top elongated hollowcylindrical body section 20, a bottom hollowcylindrical body section 22 shorter thansection 20, and an intermediate solid cylindrical .body section 24, the intermediate section serving as a joint between the top and'bottom sections. The joints between the-ends of thetopbody section 20 and thebottom body section 22 and theintermediate body section 24 are sealed by plastic cement such as the cement known in the-market as Epoxy cement. Any other suitable plasticcement may of course be used.

Thetop body section 20 includes thecylindrical side wall 26 formed of concrete reenforced by awire cage 28 embedded therein and shown in detail in FIG. 6. The

cage'includes a continuous wirelooped around, forming helically arrangedconvolutions 30. The convolutions are tied to each other by means of a series ofprestressed metal rods 32 extending across the'inside'thereof and lengthwise of the cage. The prestressing of therods 32 was effected by placing the rods on a hydraulic jack. The rods were pulled-or stretched by the jack and while under tensionthe :rods were welded to the insideof the convolutionsofthe cageZS-where the rods crossthe convolutions, the cage having been placed around the rods. After the welding operation, the rods were cut and released from the jack. The rods are Welded to the convolutions. The side wall has smooth outer and inner surfaces.

Thebottom body section 22 is similarly constructed, including the cylindrical side wall 34- of concrete reenforced by themetal cage 36, which cage consists of thehelical convolutions 38 and elongated reenforcingrods 40 therealong.

Theintermediate body section 24 constituting the joint between the top and bottom body sections is constituted by asolid round block 42 of concrete formed with acentral air tube 46 embedded therein and extending therethrough. Pairs ofwires 48, 48 are tangentially arranged with respect to the top of the tube. The pairs of wires cross each other and are welded to the tube. The wires are embedded in the concrete. Similar pairs ofwires 59, 56 are tangentially arranged with respect to the bottom of the tube and are welded thereto. The pairs of wires St), 50 cross each other and are embedded in the concrete. Thewires 48, 48 and 50, 5t) serve as reenforcements. During the assembly operation, thetube 46 serves as a vent, permitting air to escape from thebottom body section 22 to and through thetop body section 20.Block 42 is reenforced by ametal cage 47 embedded therein.

A series of spacedpassages 52 and 54 are formed in theside walls 26 and 34 of thetop body section 20 and thebottom body section 22, respectively, which passages are in line withsimilar passages 56 formed in theintermediate body section 24 adjacent its periphery. Aprestressed cable 58 extends through each set of aligned passages from one end of the body to the other. The cables hold the body sections securely and intimately together and for this purpose the cables are post-tensioned after insertion into the passages.

A metal bushing orcollar 60 with anannular flange 62 along one end of thebottom body section 22 is positioned in the bottom or free end of thebottom body section 22. Theflange 62 is perforated to receive the ends of thecables 58 and is provided with a shearing edge 64. While six cables are shown any desired number may be used. After the cables are inserted and post-tensioned, grout orconcrete 66 is forced through thepassages 52, 54 and 56 and while the cables are still under posttensioned condition the grout or concrete is permitted to harden and set, thus anchoring the cables in position. The protruding ends of the cables are sheared off.

When the composite pile is completely assembled, the bottom surface of theintermediate concrete block 42 will be flush with the upper flat surface 70 of the butt end 12a of thewooden pile 12. The metal bushing orcollar 60 will have slid along the butt end 12a of thewooden pile 12, causing some displacement of the wood to provide an extremely snug fit between the wood and bottomconcrete body section 22. The increased snugness provided by the bushing orcollar 60 is a material factor in developing both tensional and lateral stress resistance.

In assembling and placing the composite pile, thewooden section 12 first is driven with a pile driver in the usual way until its butt end 12a is just above the surface of the soil or water as the case may be. Thebottom body portion 22 of the assembledupper section 14 is then placed in position on top of the partially drivenwooden section 12, and a suitable mandrel (not shown) is lowered until it rests upon the top of theupper body section 20. The pile driver then-is used to drive thebottom body portion 22 of theupper section 14 of the pile down over the butt end 12a of thewooden section 12, shearing off any excess material and thereby fitting thebottom body portion 22 snugly onto the Wood.

Under most conditions of use, this improved com- 4 posite pile structure will be more than sufficiently re sistant to tensional stresses.

While I have illustrated and described the preferred embodiment of my invention, it will be understood that changes in details of construction might be made without departing from the principle of the invention and I desire therefore to be limited only by the state of the prior art and the appended claim.

I claim:

A composite pile comprising an elongated sectional body constituted by a wooden lower section and an upper concrete section, said upper concrete section having a top portion, a bottom portion and an intermediate portion, said bottom portion being shorter than the top portion, a reinforcing wire'cage embedded in the concrete in each of the top and bottom portions, said intermediate portion consitituting a joint between the top and bottom portions, said intermediate portion composed of a solid round block of concrete having a central air tube embedded in the concrete and extending vertically through the block, pairs of wires tangentially arranged with respect to the tube and being welded to the tube at the top and bottom ends thereof, said wires being embedded in the concrete and serving as reinforcements, said top, bottom and intermediate body portions having aligned passages therethrough adjacent the peripheries thereof, a cable extending through each set of aligned passages, concrete in the passages anchoring the cables in position, a metal bushing embedded in the bottom end of the bottom body portion, and a perforated flange extending about the lower edge of the bottom body portion and about the bushing on the inner surface of the bottom body portion, said perforated flange having a shearing edge on its inner end, the rods in the cage being prestressed.

References Cited in the file of this patent UNITED STATES PATENTS 1,103,334 Wilhelmi July 14, 1914 1,929,280 King Oct. 3, 1933 2,065,507 Alexander Dec. 29, 1936 2,474,660 Fitzpatrick June 28, 1949 2,933,898 Upson Apr. 26, 1960 3,047,081 Pitcher July 31, 1962 OTHER REFERENCES Fornerod: Prestressed Concrete Cylinder Piles, published by Raymond International, 140 Cedar St., New York, N. Y., 1959.

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