US2912829A - Composite piles and joiners therefor - Google Patents

Description

Nov. 17, 1959 v w. H. COBl 2,912,829

COMPOSITE FILES AND JOINERS THEREFOR Filed April 11, 1955 2 Sheets-Sheet 1 Nov. 17,1959 w. COB. 2,912,829

COMPOSITE FILES AND JOINERS THEREFOR Filed A ril 11,1955 2 Sheets-Sheet 2 United States Patent COMPOSITE PILES AND JOINERS THEREFOR Walter H. Cobi, Port Chester, N.Y.

Application April 11, 1955, Serial No. 500,440

Claims. (CI. 61-53) 0 The invention relates to composite piles and to joiners for such piles.

The invention relates more particularly to composite piles which have a lower section of timber. The upper section is preferably in the form of a concrete-filled shell of sheet steel, of the general type known as cast-in-place pile, but other forms may be used in accordance with the invention.

Further in accordance with the invention the joiner is of a type which may be lodged safely in the top end of the timber pile and which may be rigidly fastened to the bottom end of the shell section of the pile to effect a strong rigid connection between the two sections.

In the driving of piles into a stratum which is continuously covered by water or by a layer of water-soaked mud, it has been found to be advantageous, particularly from an economical viewpoint, to use composite piles, the joint between the two sections being located below the water table or mud so that the timber may be preserved for many years.

For such a joint a joiner section is used which must serve to keep the two sections rigidly in mutual contact and alignment during the driving operation so that the load from the superstructure shall be supported axially through the two sections to the firm bottom layer.

It has been found that super-structures of certain types, such as bridges and buildings, are subjected not only to unevenly distributed loads but also to wind-pressures, which will redistribute the normal loads on the piles supporting the structure and which may even set up a tensional pull on a number of the piles. It is therefore important that the joint between the two sections of a composite pile shall be capable both of sustaining the compressive load capacity of the pile and of resisting the tensional pulls that may be anticipated from time to time so that the pile under such circumstances may even serve to anchor the super-structure to the solid bottom without danger of the two sections becoming separated and thus failing in this requirement. The joint may furthermore not present a point in the combined pile structure which is weaker against bending action than the remainder of the pile.

It is a principal object of the invention to provide a composite pile, the lowersection of which is timber, in which the two sections are safely joined to conform to strength requirements.

It is a further object of the invention to provide a composite pile joiner which will answer the requirements outlined above and which is simple in construction and manufacture as well as in its application in practical use.

In accordance with a general feature of the invention the two pile sections are joined, end to end by driving the end portion of the steel pile partway into the end portion of the timber pile to provide both a frictional and a locking action between them.

In accordance with a principal feature of the invention the steel pile is terminated by a steel joiner section presenting locking areas which are angularly disposed relative to the center line of the pile to provide a locking action when driven into the end of the timber, this action being effective in overcoming axial pulling forces under actual operating conditions.

In accordance with the invention the joiner is of the type which is fastened, as by welding, to the lower edge of the steel shell or tube and is driven axially into the upper end portion of the timber section of the pile a sufiicient distance to effect the required friction against withdrawal from the pile under tensional force, as referred to above.

In accordance with a specific feature of the invention the joiner is comprised of a vertical hollow body portion having a collar for fastening to the steel shell. The body portion is of a cylindrical shape and has a wall thin enough to permit it to be driven down between the fibers in the end of the timber for frictional lodging there. The body portion is provided with a few wide fins extending lengthwise thereof so that they will be driven down between the fibers, thus providing additional friction with the timber against withdrawal.

In accordance with another important feature of the invention the friction secured by a given structure of this type is further increased by disposing the fins along the vertical wall at an angle with the vertical direction for each to define in effect a steep screw line. The effective resistance to withdrawal of the joiner from the timber end thus may be represented by both vertical and rotary componentswhich apply to the fins and also to the body portion.

In accordance with still another feature of the invention the body portion of the joiner comprises a plurality of complementary circumferential sections each having a fin formed of the wall material and bent at an angle not only relative to the wall section but also relative to the vertical direction of the joiner. The sections are welded together into a hollow tubular body.

The structure presenting the features referred to above lends itself to various modifications, as will appear from the following detailed description and the attached drawing, without a departure from the principles and scope of the invention, as defined by the appended claims.

For a fuller understanding of the principles and features of the invention reference is made to the following description of a preferred specific embodiment.

In the drawings:

Fig. 1 is a simplified view of a composite pile driven into position in watery ground;

Fig. 2 is a similar view of the intermediate condition when the two pile sections are about to be joined;

Fig. 3 is a detail view in perspective and with parts broken away of a joiner of a preferred construction;

Fig. 4 is a plan view of the blank used for each angular section of the joiner;

Fig. 5 is a perspective view of the plurality of separate sections formed from blanks, such as shown in Fig. 4, and ready to be assembled by welding;

Fig. 6 is a composite detail view of the joint between a timber pile and the shell for a concrete pile with parts broken away to show the joiner in position; and

Fig. 7 shows in perspective an alternative form for the joiner.

In Fig. 1 a joined composite pile 10 is 'shown as having been driven in position in a place where the subterranean layer A is fairly solid, the layer B above that is muddy or water soaked, and the surface layer C is fairly firm. Thus the layer A may be assumed to be firm enough for support to a superstructure. The layer B provides protection for the timber against atmospheric influences, the upper end of the timber being driven below safe water level. The layer C may of course be water, in which case the driving rig would be mounted on a barge; in such case the timber pile may end higher than shown in the drawing.

The watery condition of the location shown in Fig. 1 offers the advantage that timber may be used for a considerable length of the pile, timber being less expensive than constructed piles.

Thus the composite pile, shown in Fig. 1 is comprised of a timber pile first driven in until the top end is a convenient distance above ground level, as shown in Fig. 2. Above the timber section the pile has a section 30, which in the present instance comprises an outer sheet steel shell with helical corrugations and which will be filled with cement 34 after the combined sections have been fully driven into position in the ground, thereby completing the mandrel and imparting thereto its re quired strength. The pile further comprises the joiner 4-9 for securely joining the two sections, so that the pile may withstand specified stresses whether these be pulling, compressing or bending.

The pile shell 30 with the joiner 415 Welded thereto is placed over the timber butt, as shown in Fig. 2, and by means of an inner mandrel 61 (see also Fig. 6) reaching through its entire length it is connected to the butt by driving the joiner into it, thereby forming the structure as it appears in Fig. 1. Then the mandrel, acting through the joiner, drives the timber pile down into the layer A for firm lodging as shown in Fig. 1. The timber pile may of course begin moving deeper into the layer A while the joiner is being driven into the timber.

The joiner 4a is shown detached in Fig. 3 and also within the assembled pile in Fig. 6. It is of plate steel and has a cylindrical body portion 42 the upper edge of which is extended to form a continuous collar or flange 44. This collar may extend outward substantially at right angles.

A plurality of evenly distributed wings or fins 46, three in the present instance, project inward substantially at right angles from the inner surface of the body 42 and run lengthwise of the cylinder from the bottom edge and upward beyond the upper edge, projecting a distance about equal to the radial width of the flange.

The wings are however placed at a small angle with the centerline of the cylinder to form, in effect, a steep screw line inside the body 42. The wings may furthermore be tapered slightly, growing wider upward. The wings thus present areas following screw lines which during insertion into the end of the timber will turn the body portion 42 in one direction and which under an upward pull on the joiner would tend to turn the joiner in the opposite direction.

The joiner 45b is attached watertight to the bottom edge 32. of the corrugated shell 36 this edge being welded to the flange 44, as shown in Fig. 6.

With the mandrel 60 lowered into position within the steel pile the joiner is placed with its lower edge against the top surface of the timber 2d, the diameter of which preferably is l to 2 inches larger, and the mandrel can start driving with its bottom plate 62 striking against the upper projections of the wings 46. The lower edges of the body portion 42 and of the wings will force their way down into the wood, the cylinder going in COIl centrically with the centerline and the wings forcing their Way in along the screwline defined by their angular disposition, thereby turning the whole joiner slightly about its axis.

This small twist is readily taken up on the mandrel, which will turn in the rig. The circular shape of the body 42 will offer only some frictional resistance to this locking twist.

When the top edges of the fins come flush with the top surface of the pole the condition will be as shown in Fig. 6 and the joiner will be in its proper position. Thereafter the driving mandrel will be driving on the pole. The pole may of course begin to sink deeper in the ground during the screw action of the joiner relative to the stub.

With the center stub 22 of the timber filling the joiner, the driving may continue through mud or water without water entering the interior of the mandrel. Thus the cement mixture later poured into the shell will not be leached out.

When the driving is completed the mandrel is removed from pile shell 30 which then may be filled with cement to a required height, thereby completing the composite pile.

The fins add considerable friction along their surfaces against an upward movement, but additional resistance is offered due to the angular direction of the clefts in the wood in which the wings are pinched, whereby an upward pull on the joiner relative to the timber would tend to rotate the joiner and the whole upper pile section 30. Such rotation being impossible in an ultimate installation, the alternatives would be for the force to tear a plug of wood out at each fin or to deform the surrounding wood and the wings for straight upward movement of the joiner. Thus the locking twist given the joiner relative to the timber stub at the time of setting the pile has added a very great resistance against a force tending to tear the joiner ofl the stub.

By careful welding of the bottom edge 32 of the shell to the collar 4 and by heavy tamping of the first charge of cement into the channel along the upper side of the flange 44 and into contact with the end surface of the stub an even stronger connection between joiner and cement pile may readily be obtained.

Joints using joiners of this type have been laboratory tested for longitudinal pull and have been shown to resist considerably greater pulling force than that prescribed by building codes.

As an example the joiner may have the following approximate dimensions: diameter 11 inches, depth 6 inches, three wings 1% and 1 inch deep at top and bottom, respectively, with an angular shift of 1 inch between top and bottom.

The number of fins and their angle may be varied according to the size of the mandrel. With the objects of providing effective resistance to withdrawal and of not unduly obstructing insertion of the joiner into the Wood the angle may vary from /2 to 1%. inches, much depending upon the depth of the joiner.

The shape of cross-sections taken at any height of the joiner should be substantially the same to permit fairly easy insertion with a minimum of disturbance to the fibres, particularly about the fins. If desired the fins may be sharpened at the bottom edge to cut clean across the fibres, thereby permitting some increase in the angle of the fins.

For use with the present joiner, the usual practice of shaving the upper end of the timber pile down to correct diameter will be unnecessary, as will also the use of the usual reenforcing ring for the shaved-down stub.

As shown in Figs. 3, 4 and 5 the joiner is designed so that it can be constructed from identical parts 50, one part only for each wing.

Each part is made from a blank 51 of plate steel, which may be from A3 to inch thick depending on the diameter of the pile. For the example given above it may be inch thick.

The blank is slit at 52 so that the flange portion may be bent out along the line 53 and so that the fin may be bent in along the line 54, which is directed at the desired angle for defining the screw line of the finished fin. The edge 55 is cut at the same angle. The edge 56 may be out parallel with the line 54 or at an angle therewith in the case of a tapered wing, as shown in Fig. 4. The remaining body portion of the blank is curved with the flange to fit into the cylindrical shape formed with the other similar parts, as shown in Fig. 5.

The three parts 50 in the example are joined by welding of the edge 55 of one part to the bent edge 54 of the adjacent part. Some grinding off of irregularities may be necessary in an efficient job.

An alternative shape of joiners with screwline areas is shown in Fig. 7.

In this joiner 40a, the fins 46a present triangular areas tapered upward and do not extend above the flange 44a. All other details are the same as in the joiner in Fig. 3. This design may simplify the manufacture.

The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that Various modifications are possible within the scope of the invention claimed.

I claim:

1. A steel joiner for joining a steel pile shell section to a timber section which comprises a body portion defined by a cylindrical side wall forming a cylinder open at its opposite ends, a flange extending outwardly from the upper end of said cylindrical side wall for attachment to said pile shell section, and a plurality of flat fins extending along the inner surface of said cylindrical side wall and disposed at an angle relative to the central axis of said body portion, each of said fins extending from said cylindrical wall toward but terminating short of said axis for driving into the upper end portion of the timber section, each of said fins being disposedin a screw-thread line relative to said axis.

2. A self-locking joiner for joining the upper end of a timber pile to the lower end of a steel pile shell for producing a composite pile the lower portion of which is timber and the upper portion of which is-cast-in-pl ace concrete, said joiner comprising a cylindrically shaped wall portion for driving onto the upper end of said timber portion, said cylindrically shaped wall portion forming a cylinder open at its opposite ends, a plurality of circumferentially spaced fins extending inward from the interior surface of said cylindrically shaped wall portion and terminating short of the central axis of said cylindrically shaped wall portion, said fins extending along theinner surface of said cylindrically shaped wall portion angularly with respect to said axis, each fin forming a steep pitch line with said axis and being drivable into the wood of said timber portion, whereby said fins' cause said joiner to rotate with respect to said central axis as said joiner is driven onto the upper end of said timber portion to provide a locking means requiring a force having a rotational component in addition to an axial component to separate said joiner from said timber portion after the joiner is driven onto the timber portion.

3. A self-locking joiner for joining the upper end of a timber pile to the lower end of a steel pipe shell of generally cylindrical shape for producing a composite pile the lower portion of which is timber and the upper portion of which is concrete cast in said steel shell, said joiner comprising a cylindrically shaped wall portion, said cylindrically shaped wall portion forming a cylinder open at its opposite ends, a plurality of circumferentially and equally spaced fiat fin members extending inwardly in-a general radial direction from said cylindrically shaped wall portion and terminating short of the central axis of said cylindrically shaped wall portion, said fins extending along the inner surface of said cylindrically shaped wall portion angularly with respect to said axis, each of said fins being disposed along a screw thread line having a steep pitch and being drivable into the wood of said timber portion and a flange extending outwardly from the periphery of the upper end of said cylindrical wall portion in a plane at right angles to said axis forming a shoulder to which may be welded the lower end of the steel pile shell, whereby said fins cause said joiner to'rota'te with respect to said timber portion as said joiner is driven onto said timber portion to thereby provide a locking means requiring a force having a rotational component and an axial component to separate said joiner from said timber portion after the joiner is driven onto the upper end of the timber portion.

4. A joiner constructed as specified in claim 3 in which there are three of said fins spaced apart.

5. A composite pile comprising a lower timber section joined in axial alignment to an upper section comprising a steel casing having a cylindrical wall of generally circular cross section in whichis contained concrete, said upper and lower sections being joined together by a selflocking joiner having a cylindrical side wall driven into the wood at the upper end of said timber section, said cylindrical side wall forming a cylinder open at its oposite ends, fins extending inwardly from said cylindrical wall and terminating short of the central axis of said pile, said fins extendingalong the inner surface of said cylindrical side wall angularly with respect to said axis and each fin following a screw thread line on the inner side of said cylindrical side wall and being embedded in said wood to provide a locking means requiring a force having both a rotational and axial component to separate said upper and lower sections.

Dunn -QNov. 3, 1868 Watt Apr. 13, 1915 Watt July 4, 1933 Nadel Aug. 28, 1934 UNITED STATES PATENT emct:

CERTIFICATE 0F CORECEN Patent No.. 2 ,912 ,829 November 1'7, 1959 Walter Hn Gobi It is hereby certified that error appears in the -printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5 line 55, for "pipe" read w pile --o Signed and sealed this 10th day of May 1960.,

(SEAL) Attest:

ROBERT c. WATSON KARL Ho .AXLINE Attesting Officer Commissioner of Patents

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