SELF-INTERLOCKING MEANS FOR END TO END JOINTING OF ELONGATED CONCRETE ELEMENTS, ESPECIALLY OF CONCRETE PILES

Abstract: A self-interlocking means for end to end jointing of elongated concrete elements, especially concrete piles, comprises two end plates (1) and substantially straight glide bars (10) to be forced into slightly curved locking grooves (2) in the end plates and running from one peripheral side (4) of the end plate (1) to the opposite peripheral side (5) of the end plate and being open to both these sides. When the end to end jointing of two elongated concrete elements is performed, an end plate (1) will be attached to each of the two ends to be jointed. The end plates (1) are brought together in abutting relationship so that the locking grooves (2) of one end plate (1) will be exactly opposite the corresponding locking grooves (2) in the other end plate (1), and the glide bars (10) are forced into the lateral openings formed by each pair of exactly oppositely located locking grooves (2), thereby interlockingly pressing the two abutting end plates (1) together.

Description: Self-interlocking means for end to end iointinσ of elongated concrete elements, especially of concrete piles Field of the invention The invention relates to the jointing of ends of elongated concrete elements, especially concrete piles, and more particularly to a self-interlocking means for jointing abutting ends of two such elements. Although the invention will be described below with reference to the jointing of abutting ends of concrete piles to be rammed into the ground, it will be understood that the invention also relates to a means for jointing ends of any elongated structural concrete elements which occasionally need to be joined together end to end, like e.g. reinforced concrete beams. The Prior Art For obtaining a such end to end jointing of concrete piles mainly male-female jointing means in accordance with the bayonet catch principle are used today. A such joint is shown e.g. in Swedish laid open application No. 403156. There are also other types of jointing means on the market, however, they all have in common that they do not satisfy the requirements according to Norwegian Standard NS3420 2.edition H12.52. The disadvantages of the currently used jointing or locking means for end to end jointing of concrete piles are, besides the joint not becoming sufficiently strong, that at the building sites both bottom piles, intermediate piles and top piles of various lengths must be available dependent upon the depth to which the ramming of the piles into the ground shall be made. In order to avoid unnecessary loss of pile lengths regard must be taken to the pile lengths which are being rammed down. Half the length of a pile is very often lost. Further, regard must be taken to the storage of the piles at the building construction site both with respect to the types of piles and the lengths of the piles and to storing the piles in the correct direction with respect to female and male ends. The reinforcement in the piles must due to the known locking principle used be anchored near the center of the end of the pile. This causes the joint to fail to obtain the same strength as the pile itself. s A jointing means for concrete piles is disclosed and illustrated in Norwegian laid open application No. 133415, wherein to each of two pile ends to be jointed a shoe is at¬ tached which comprises at least two, preferably four, guides which are open outwardly towards the outer surface of the ι° locking shoe and which extend a distance inwardly into the locking shoe from opposite sides thereof. When the pile ends are to be jointed, the pile ends with locking shoes attached thereto are placed into abutting relationship so that the guides in one shoe will be exactly opposite the corresponding s guides in the abutting shoe attached to the end of the other pile. Locking bars are then introduced from the outside into the oppositely facing guides of the two abutting locking shoes, the locking bars being provided with two flange portions which upon forcing locking bars into the guides are 0 received in matchingly shaped hollow spaces in the guides. For this known jointing means the guides as well as the locking bars are of relatively complex shape, and a locking which runs uninterruptedly from one side of the concrete pile end to the opposite side of the concrete pile end is not obtained. 5 A similar locking system has been been disclosed and illustrated in Swedish laid open application No. 449499. This locking system comprises end plates for attachment to the ends of piles to be jointed. Each end plate is provided with guides into which locking bars are to be forced. According to an il- 0 lustrated embodiment, each end plate is provided with four separate guides. The guides extend a distance inwardly from opposite sides of the end plate. Also here the guides and the locking bars adapted thereto are of relatively complex shape in order to ensure locking of two abutting end plates together 5 upon forcing the locking bars into the guides, and the locking system does not provide locking of the end plates to one another uninterruptedly from one side of each end plate to the opposite side of the end plate. Objects of the invention It is an object of the present invention to provide a self-interlocking means for jointing the ends of two concrete piles while obtaining interlocking of the two concrete piles 5 uninterruptedly from one side of the end of the concrete pile to the opposite side of the end of the concrete pile, in order to provide a joint which will satisfy the requirements accor¬ ding to Norwegian Standard NS3420 2.edition H12.52. It is a further object of the invention to provide a o locking means wherein locking grooves in each end plate may be of relatively simple shape with correspondingly simple shape for the locking bars (here termed "glide bars"). It is also an object of the invention that the lock¬ ing grooves may be formed integrally with the end plate making s it unnecessary to provide separate guides which must be attached to the end plates, like the guides which form the locking grooves of the jointing means according to said Nor¬ wegian laid open application No. 133415. It is a further object of the invention to provide a o self-interlocking lock such that both ends of a pile are equal when the end plates have been attached thereto. Accordingly, only one type of piles will be necessary which can be produced for storage, and this will facilitate storing the piles at the building or construction sites. If the top pile upon ramming 5 into the ground is too long, then this pile may be cut off, and upon turning the cut off top portion of the pile upside down the end plate attached to the end of the cut off pile portion may then be interlocked with the end plate attached to the top end of another pile rammed into the ground if the lat- o ter is too short. Further, it is an object of the invention that the lock is to be simple to use by making it easy to align the concrete pile ends to be jointed and by providing a locking end plate with locking grooves into which locking bars ( "glide 5 bars") may be forced from either side of the end plate. Brief disclosure of the invention These objects are obtained according to the invention by means of a self-interlocking means for end to end jointing of elongated concrete elements, especially concrete piles, comprising two end plates to be attached respectively to each of two concrete element ends to be jointed and which when jointing is to be performed are abutting each other, each end 5 plate comprising locking grooves which are open towards an outer surface of the end plate and which when jointing said two ends of the two concrete elements will be located exactly opposite corresponding locking grooves in the abutting end plate attached to the end of the other concrete element, the o self-interlocking means further comprising glide bars for being forced into the locking grooves of the two opposite and abutting end plates with obtainment of interlocking bridging therebetween, the glide bars having a volume and a shape such that the glide bars essentially completely fill the locking s grooves upon having been forced thereinto, each locking groove having a horizontal opening cross section which is smaller than a largest horizontal cross section in the depth of the groove, and each glide bar having a vertical cross sectional shape which essentially corresponds to the vertical cross o sectional shape of two exactly oppositely located locking grooves of the two abutting end plates when the end jointing is to be performed, characterized in that each end plate is provided with two slightly curved locking grooves, each locking groove having its smallest horizontal cross section 5 at its opening towards said one outer surface, and each locking groove running from one peripheral side of the end plate to the opposite peripheral side of the end plate and is open to both these sides, and the glide bars being straight or essentially straight prior to being forced into the locking grooves. According to a preferred embodiment of the invention the walls of each locking groove converge outwardly toward the edges of the locking groove. Thereby good interlocking of the end plates is obtained against forces which act to pull the abutting end plates away from each other. It is further advantageous in order to obtain an optimum locking against torsional or bending forces which act in the lateral direction of the pile joint that the two curved locking grooves of each end plate are oppositely curved with their concavities facing one another. In order to facilitate forcing of the glide bars into the locking grooves it is also advantageous that the locking grooves have an entrance portion which is straight or substantially straight and that the entrance portion passes over into a curved middle portion which in its turn passes over into a straight or substantially straight exit portion. The curved middle portion of the locking groove may then comprise e.g. about half of the total length of the locking groove, whereby each straight end portion of the locking groove will comprise about 1/4 of the total length of the locking groove. The locking groove may also have a wave-line type run having at least two slightly curved portions. Here again it is preferred that the entrance portion and the exit portion of the locking groove are straight or essentialy straight. In order to protect the sides of the pile ends it is further advantageous that each end plate is provided with upright cover plates. The end plates are attached to the concrete pile ends in a conventional manner, e.g. by casting the concrete piles in horizontal moulds wherein an end plate to which anchoring bars have been securedly attached is vertically arranged at one end or at both ends of the casting mould, and with the reinforcement of the concrete pile arranged in the casting moulds. After casting of the concrete and upon solidification thereof the finished pile will have been provided with a well anchored end plate cast onto the concrete pile at one end thereof or at both ends thereof. Brief description of the drawings The invention will now be further explained with reference to embodiments of the self-interlocking means shown in the attached drawings. In these Fig. 1 shows a perspective view of an end plate provided with cover plates and with anchoring bars secured thereto, facing downwards, Fig. 2 shows a perspective view of a corresponding end plate as shown in Fig. 1, facing upwards, and, moreover, two glide bars for being forced into the two locking grooves of the end plate. Fig. 3 shows a vertical section through the self-interlocking means according to the invention upon the glide bars having s been forced into the end plates and are pressing the end plates against one another, Fig. 4 shows a similar prespective view as shown in Fig. 1, however, with another and preferred arrangement of the anchoring bars, Fig. 5 shows a perspective view of the end plate according to Fig. 4, however, with the end plate being turned upwards, and Fig. 6 shows a vertical section similar to the section shown in Fig. 3, however, with the preferred arrangement of the anchoring bars. Detailed description of the drawings and of the invention with best mode Referring to the drawings, Fig. 1 shows an end plate 1 of steel provided with cover plates 6. The end plate is provided with two locking grooves 2 which run from one side 4 of the end plate to the opposite side 5 thereof. The walls 3 of the locking grooves 2 converge outwardly towards the edges of the locking groove. According to the embodiment shown, the locking grooves 2 have a bottom 7 of triangular cross section. This bottom leaves space for plastic deformation of glide bars 10 (Fig. 2 ) when glide bars are forced into the locking grooves 2, and, moreover, the bottom 7 yields space for receipt of "foreign particles", like clay, sand, etc. Further, the end plate is provided with openings 8 for receiving and securely retaining reinforcement bars or anchoring bars 9. In order to obtain a secure attachment of the bars 9 in the openings 8 the latter may be provided with internal threads for threadingly securing bars 9 therein having exterior end threads adapted to the internal threads of the openings 8. in Fig. 2 the same reference numerals denote the same details as in Fig. 1. Moreover, in Fig. 2 a guide pin 11 has been shown which is located in a hole 12 in the end plate and which fits into a corresponding hole in the end plate which will become abutting to the former end plate when the two end plates are placed against one another when jointing the ends of two concrete elements is performed. Two straight glide bars 10 have been shown in Fig. 2. The glide bars have essentially the same length as the length of the locking grooves, and they 5 have a vertical cross sectional shape which corresponds or essentially corresponds to the vertical cross sectional shape of two locking grooves 2 arranged exactly opposite one another, one of the locking grooves 2 being provided in one of the end plates and the other of the locking grooves 2 being o provided in another and abutting end plate when the end to end jointing of two elongated concrete elements is to be performed. When the glide bars 10 are forced from outside into the opening formed by two exactly oppositely located grooves of two abutting end plates, each glide bar 10 will essentially s completely fill the two exactly oppositely located locking grooves 2. In order to be able to force the glide bars 10 into the locking grooves 2 the glide bars should be made of a material which when forcing the glide bars 10 into the locking grooves 2 may adapt their shape to the curvature of o the locking grooves, and a suitable material for the glide bars is nodular iron of a quality corresponding to a hot rolled material, e.g. St52-3N. Also the end plates may be made of the same material. However, also other metallic materials, e.g. alloys, having a certain ductility may be used for the = glide bars. As a consequence of the slightly curved run of the locking grooves 2, whereas the glide bars are straight or substantially straight, the glide bars 10 will automatically be kept interlocked in the locking grooves when the glide bars have been forced into the locking grooves, e.g. by knocking o them into the locking grooves. The cover plates 6 have been shown attached to the end plate 1 by means of spot welding, however, due to the simple shape of the end plate the latter with cover plates may be cast as one piece making any subsequent working of the end 5 plate with cutting tools unnecessary. Fig. 3 shows a cross section through the self- interlocking means or lock according to the invention, wherein two end plates 1 provided with cover walls 6 have been pressed against one another by means of glide bars 10 which have been '*' " forced into the locking grooves which are located exactly «***- opposite one another in the two end plates 1. Further, it has been shown in Fig. 3 how the guide pin 11 in the openings 12 of the two end plates 1 is arranged in a guide 13 and assists 5 in centering the two end plates so that the locking grooves of one end plate will come to be exactly opposite the corresponding locking grooves in the other end plate. Fig. 4 and Fig. 5 show the anchoring bars 9 fixedly attached to the end plate 1 in the preferred arrangement of s the anchoring bars, and Fig. 6 shows a cross section through the self-interlocking lock according to the invention, with the anchoring bars 9 secured in preferred manner in openings 8 in raised portions 14 of the end plate material right above the locking grooves 2. By this arrangement of the anchoring i5 bars 9 it has been found that the self-interlocking joint may take up the highest possible bending or torsional moment when ramming the piles into the ground. Because the locking groves 2 pass uninterruptedly from one side 4 of the end plate 2 to the opposite side 5 of 20 the end plate it is in contrast to the previously known locking means for end to end jointing of concrete piles possible to force the glide bars 10 which have been driven into the locking grooves 2, out of the locking grooves 2 if this should be desirable, whereby the connection between two -= abutting pile ends will be easily disconnected, e.g. by knocking the glide bars 10 out of the grooves 2 using punch and hammer. The through curved locking grooves 2, the curved middle portion of the locking grooves 2 or the curved portions so (wave-line type) of the locking grooves 2 may have a radius of curvature which may vary considerably, Thus, the radius of curvature may be from 1 to 3 m, preferably about 2 m, in order to ensure sufficient interlocking of the glide bars 10 upon forcing the glide bars into the locking grooves 2. 35 The principle of two curved locking grooves 2 which pass uniterruptedly from one side of each end plate 1 to the opposite side of each end plate 1 may be used not only for end plates of rectangular shape, as shown in the drawings, but also for end plates of other shapes for end to end jointing of elongated concrete elements having a cross sectional shape other than rectangular or square. It has been shown in the figures that the anchoring bars 9 are symmetrically arranged about the center opening 12 s of the end plate 1. A such symmetrical arrangement of anchoring bars 9 permits the arrangement of a larger number of reinforcement bars in the concrete between the anchoring bars 9 and the end plate 1 than what would have been the case with another arrangement of the anchoring bars 9. By the o arrangement according to the invention of the anchoring bars 9 it has been possible to introduce as many as eight reinforcement bars in the concrete between the anchoring bars 9 and the end plate 1. For the self-interlocking means according to the invention the anchoring bars 9 ought to have s the same cross sectional dimension as the reinforcement bars used in the concrete, in order to obtain the highest possible uniform strength from end to end of the elongated concrete element. 0 0 5

Claims: C l a i m s 1. Self-interlocking means for end to end jointing of elongated concrete elements, especially concrete piles, s comprising two end plates (1) to be attached respectively to each of two concrete element ends to be jointed and which when jointing is to be performed are abutting each other, each end plate (1) comprising locking grooves (2) which are open towards an outer surface of the end plate and which when ιo jointing said two ends of the two concrete elements will be located exactly opposite the corresponding locking grooves in the abutting end plate (1) attached to the end of the other concrete element, the self-interlocking means further comprising glide bars (10) for being forced into the locking ι= grooves (2) of the two opposite and abutting end plates (1) with obtainment of interlocking bridging therebetween, the glide bars (10) having a volume and a shape such that the glide bars essentially completely fill the locking grooves (2) upon having been forced thereinto, each locking groove (2) 0 having a horizontal opening cross section which is smaller than a largest horizontal cross section in the depth of the groove (2), and each glide bar (10) having a vertical cross sectional shape which essentially corresponds to the vertical cross sectional shape of two exactly oppositely located = locking grooves (2) of the two abutting end plates (1) when the end jointing is to be performed, characterized in that each end plate (1) is provided with two slightly curved locking grooves, each locking groove (2) having its smallest horizontal cross section at its opening towards said one outer 0 surface, and each locking groove (2) running from one peripheral side (4) of the end plate (1) to the opposite peripheral side (5) of the end plate and being open to both these sides, and the glide bars (10) being straight or essentially straight prior to being forced into the locking 5 grooves (2). 2. Self-interlocking means according to claim 1, characterized in that the walls (3) of each locking groove (2) converge outwardly towards the edges of the locking groove. 3. Self-interlocking means according to claim 1 or 2 , characterized in that the two locking grooves (2) of each end plate (1) are oppositely curved with their concavities facing one another. 5 4. Self-interlocking means according to anyone of claims 1 to 3, characterized in that the two locking grooves (2) in each end plate (1) are symmetrically formed on each side of a theoretical line of symmetry drawn through the center of the o end plate (1) from said one peripheral side (4) to said opposite peripheral side (5). 5. Self-interlocking means according to anyone of claims 1 to 4, characterized in that each locking groove (2) has a s straight or substantially straight entrance portion, a corresponding straight or essentially straight exit portion and a slightly curved middle portion. 6. Self-interlocking means according to anyone of claims 0 1 to 4, characterized in that each locking groove (2) has a wave-like pattern with at least two slightly curved portions. 7. Self-interlocking means according to anyone of claims 5 1 to 6, characterized in that the bottom (7) of each locking groove (2) is of triangular cross section. 8. Self-interlocking means according to anyone of claims 1 to 7, characterized in that each end plate (1) is provided o with cover plates (6) upright from each end plate for protecting the sides of the end of the concrete element. 9. Self- interlocking means according to anyone of claims 1 to 8, characterized in that each end plate (1) on 5 that side thereof which will be facing the end of the concrete element when jointing is to be performed, is provided with openings (8) for securing reinforcement bars or anchoring bars (9) therein. 10. Self-interlocking means according to claim 9, characterized in that the openings (8) for securing reinforcement bars or anchoring bars (9) therein are formed in raised portions (14) of the end plate (1) right above the locking grooves (2).

Inventors: FREDRIKSEN ARNFINN, HALDORSEN ROLF, HANSEN WILHELM OTTO, ROSFJORD BJOERN, FREDRIKSEN, ARNFINN, HALDORSEN, ROLF, HANSEN, WILHELM, OTTO, ROSFJORD, BJOERN
Applicants: FREDRIKSEN ARNFINN, HALDORSEN ROLF, HANSEN WILHELM OTTO, ROSFJORD BJOERN, FREDRIKSEN, ARNFINN, HALDORSEN, ROLF, HANSEN, WILHELM, OTTO, ROSFJORD, BJOERN
Application year: 1992
Main classification: E02D5
IPC codes: E02D5