US 2036793 A
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Patented Apr. 7, 1936 UNITED STATES PATENT OFFICE CONCRETE PILE CONSTRUCTION Application November 9, 1934, Serial No. 752,224
Ihis invention pertains to the construction of concrete piles of unusual length.
In practice there is a rather well-delined limit to the length of pre-cast concrete piles which may be economically handled. One of the limitations is, of course, the increased mass which is the natural result of increased length. Then there is a very serious problem in the use of precast piles of extreme length for the reason that an excessive amount of reinforcement is required to make the pile strong enough to stand the stresses due to handling, the amount of reinforcing steel required for that purpose being greater than the amount required in the pile after it is in use. Furthermore, the necessary equipment for handling extra long heavy piles is extremely expensive, due not only to the weights to be handled but to the extreme height of the driver and handling derricks.
Attempts have been made to overcome the above difficulties by driving steel pipes to be lled with concrete after driving. But even though that type `of pile offers no great handling diniculties it has its economical limitations due to the cost of the pipe, which becomes prohibitive beyond certain dimensions. The present invention seeks to solve the problem by disclosing a particular kind of composite pile having a lower pipe section, and a concrete upper section which is made as long as can be handled, thus making the pipe section as short as possible in order to reduce cost. Composite piles having pipe sections and pre-cast concrete sections are not broadly new, but according to previous practice, the pre-cast concrete member would usually be driven rst and the pipe section placed on top of the pre-cast member, since it is easier to put the long member in the ground rst and then drive the combined unit to a penetration suf- .:cient to carry the ultimate load. However, this involves stopping the driving when the pile has attained a position that makes it necessary to add the top section. When such driving ceases, the ground normally grips the pile to a degree that makes it almost impossible to re-start it, particularly when the pile mass is so much in excess of the mass of the driving hammer.
By driving the hollow pipe first, as in the present invention, this particular objection is overcome, rst, because the mass of the hollow pipe is not so excessive with relation to the mass of the hammer, and second, on account of the nature of the steel pipe the vibrations induced by the hammer blows tend to loosen the shell from the ground which grips it. Furthermore,
the upper concrete section is in the form of a hollow shell, thus greatly reducing its mass and permitting the driving of pile lengths never before possible, so far as I am aware.
Broadly then, the invention contemplates the 5 use of an upper pre-cast concrete section as long as can be handled, and a lower section of steel pipe. The upper pre-cast concrete section is made in the form of a hollow shell to reduce its weight and to provide a passage or conduit l0 therethrough by means of which the lower pile section may be llled with concrete after the driving is completed, the lling, of course, extending into the upper concrete shell so as to form a monolithic core and integral with the l5 pipe comprising the lower shell, and with the concrete comprising the upper shell, the core extending as far as desired into the upper shell.
The lower end of the concrete shell is provided with a tubular tenon which extends a certain 270 distance into the top of the lower pipe section to keep upper and lower shells in alignment. Also, the upper end of the tenon is encased in a steel sleeve, and reinforcing rods extending through the pre-cast concrete shell are welded 25 to the sleeve.Y The sleeve is in abutting relationship with the top of the lower pipe shell in order to transmit the driving effect to the pipe. Engagement of the sleeve with the upper concrete shell is accomplished by the reinforcing rods 30 welded to the sleeve, by abutment of the upper end of the sleeve with a shoulder on the concrete shell, and by the bond between the sleeve and the concrete of the tenon.
Further and other objects and advantages will 35 be apparent from the specication and claims, and from the accompanying drawings which illustrate what is now considered the preferred embodiment of the invention.
Fig. 1 is an elevation of the completed pile, 40 the lower section being circular in cross-section and the upper section being square in cross-section.
Fig. 2 is a cross-section of the pile taken on the shortest diameter of the upper square section and showing only the short set of reinforcing bars, designated B.
Fig, 3 is a cross-section taken on the long diameter of the square section and showing only the long reinforcing bars, designated A, which are placed in the corners of the square section.
Fig. 4 is a cross-section on line 4 4 of Fig. 2, but showing bars A and B.
Fig. 5 is a cross-section on line 5 5 of Fig. 2, but showing bars A and B.
Fig. 6 is a cross-section on line 6 6 of Fig. 3, but showing bars A and B.
Fig. 7 is a cross-section on line 'i-'l of Fig. 2, but showing bars A and B.
Fig. 8 is a cross-section of the upper end of the lower section and lower end of the upper section of the pile with modified form of reinforcement.
Fig. 9 is a cross-section on line 9 9 of Fig. 8.
In the drawings, 2t designates the pipe comprising the lower shell, 22 the driving point fitted to the lower end of shell 20, and 2d. a collar surrounding and welded to the upper end of shell 20, the collar projecting above the top of shell 2U.
26 designates the square pre-cast concrete upper shell. The lower end of shell 26 beginning at the point 28 is shaped in the form of an annular tenon 3U of such diameter as to fit snugly within the upper end of steel shell 20, thereby holding the upper and lower shells in alignment during the driving operation. The upper part of tenon 30 is encased in a steel sleeve 32, this sleeve being of the same external diameter as shell 20 so that when the tenon is slipped down into shell 2?, sleeve 32 will enter collar 24 and rest in abutting relationship with the top of shell 2B at point 34 (Figs. 2 and 3). The upper end of sleeve 32 is in abutting relationship with a shoulder 28 on the upper concrete shell.
In the illustrated embodiment of the invention, the upper concrete shell is equipped with two sets of reinforcing rods. The rods comprising set A, Figs. 3, 4, 5, 6 and 7, extend from the bottom of the tenon upwardly into the body of the shell where they are bent so as to occupy positions near the corners of the square shell (Figs. 3 and 4). These rods, when passing through the upper part of the tenon are bent into contact with sleeve 32 and are welded to the sleeve as indicated at 36. The other set of reinforcing rods designated B extend from the bottom of the tenon up through the tenon and for a limited distance into the upper shell at points from rods A. Rods B are brought into contact with, and welded to, sleeve 32 at points designated 38, Fig. 2. The vertical reinforcing bars are encircled by reinforcing rings 40, 42 and 52 in the usual manner.
In practice, lower shell 2G is rst driven. When its upper end approaches ground level, the upper concrete shell 25 is mounted on shell 2E), the tenon 3E (bevelled at its lower end as at 44 so as to easily enter shell 2Q), passes down into shell 2li until the lower end of sleeve 32 rests, within collar 24, at 34 on the top of shell 2). Then with the tenon holding the upper and lower shells in alignment, the two shells are driven into the ground by blows applied to the upper end of the concrete shell. The driving effect is transmitted from the upper concrete shell t0 the lower pipe shell by the abutting contact of sleeve 32 with the top of shell 29. The concrete comprising upper shell 26 transmits the driving effect to sleeve 32 by means of bars A and B which are embedded in the concrete and welded to the sleeve, by abutment of the top of sleeve 32 with shoulder 28, and by the bond between the concrete and the inside of the sleeve, which is very intimate because the concrete is cast into sleeve 32. Collar 24 on the outside of the joint between sleeve 32 and shell 26, and tenon '39 on the inside of that same joint, serve to hold sleeve 32 and shell 25 in proper alignment during driving.
In the modification shown in Figs. 8 and 9, the reinforcing bars A and B are not welded to the sleeve, the bonded relationship between the concrete and the sleeve being amplified sufficiently for some conditions by means of spaced radiating vertical plates 46 welded to the shell 32 as at 43 and extending radially inwardly, as best shown in Fig. 9.
After the driving of the upper and lower shells is completed, the lower pipe section and the cavity in the upper concrete section are filled with plastic concrete 53 which, when hardened, forms a monolithic core integral with the upper and lower shells to form the completed pile.
It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as dened by the following claims.
1. A composite pile comprising a lower shell of tubular steel, an upper shell of pre-cast concrete extending above said steel shell, and a monolithic core of concrete within said shells.
2. A composite pile comprising a lower shell of tubular steel, an upper shell of pre-cast concrete, an annular tenon projecting downwardly from the lower end of said upper shell into the upper end of said lower shell, and a monolithic core of concrete within said shells and said tenon.
3. The invention set forth in claim 2 in which said tenon is at least partially encased in a steel sleeve.
4. A composite pile comprising a lower shell of tubular steel, an upper shell of pre-cast concrete, an annular tenon projecting downwardly from the lower end of said upper shell into the upper end of said lower shell, a steel sleeve at least partially encasing said tenon, steel reinforcing bars welded to said sleeve and extending into the concrete of said upper shell, and a monolithic core of concrete within said shells and said tenon.
5. A composite pile comprising a lower shell of tubular steel, an upper shell of pre-cast concrete, an annular tenon projecting downwardly from the lower end of said upper shell into the upper end of said lower shell, a steel sleeve at least partially encasing said tenon, the lower end of said sleeve being in abutting relationship with the upper end of said steel shell, and a monolithic core of concrete within said shells and said tenon.
6. The invention set forth in claim 5 in which the upper end of said steel lower shell is provided with an annular collar welded thereto and extending upwardly around the lower end of said sleeve.
'7. The invention set forth in claim 5 in which said upper concrete shell is provided with an annular shoulder against which the upper end of said sleeve is in abutting relationship.
8. A composite pile comprising a lower shell of tubular steel, an upper shell of pre-cast con'- crete, an annular tenon projecting downwardly from the lower end of said upper shell into the upper end of said lower shell, a steel sleeve around the upper part of said tenon, the lower end of said sleeve abutting the top of said lower shell and the upper end of said sleeveV abutting said upper shell, reinforcing bars welded to said sleeve and extending into said upper shell, and a monolithic core of concrete within said shells and said tenon.
HENRY A. CHRISTIE.