JP2009287357A - Joint structure of steel pipes - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of steel pipes which eliminates a need for field welding, excels in work efficiency, and sufficiently secures required joint strength in spite of the low manufacturing cost. <P>SOLUTION: The joint structure of the steel pipes for joining the two steel pipes to each other in the axial direction comprises a joint member fitted to inner peripheral surfaces of the steel pipes astride the two steel pipes whose joint end faces at the axial end parts abut on each other, mounting jigs arranged on outer peripheral surfaces of the two steel pipes in the peripheral direction, and a cord-like body extended among the plurality of the mounting jigs on the two steel pipes in a manner of reciprocating between the steel pipes in the axial direction so that it may be wound around the two steel pipes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a joint structure for steel pipes that can connect a plurality of steel pipes used as steel pipe piles or the like in the axial direction thereof.

  Conventionally, in the field of piles such as steel pipe piles, as a technique for connecting two steel pipes in the axial direction, two methods, a method using on-site welding and a method using mechanical joints, have been proposed. . Of these, the mechanical joint methods can be classified by type into “joint structure by screwing”, “joint structure by bolt joint”, and “joint structure by fitting”.

  The joint structure by screwing here is, for example, as shown in Patent Document 1, provided with a threaded male threaded portion on the outer peripheral surface of one end of the steel pipe to be connected, and threaded on the inner peripheral surface of the other steel pipe. This means a structure in which a female threaded portion is provided and each steel pipe can be connected by screwing.

  The joint structure by bolt joining is, for example, as shown in Patent Document 2 and Patent Document 3, in which a connecting metal fitting is arranged so as to straddle the ends of two steel pipes to be connected, and this connecting metal fitting and two steel pipes It means a structure in which each steel pipe is bolted by a bolt that penetrates through.

  The joint structure by fitting is a connecting member such as a steel pipe having an outer diameter substantially the same as the inner diameter of these steel pipes in two steel pipes to be connected, as shown in Patent Document 4 and Patent Document 5, for example. Is a structure that allows two steel pipes to be connected by fitting them together.

  Incidentally, in Patent Document 4, the lower steel pipe is provided with a protruding portion that protrudes radially outward, and after inserting the protruding portion into the engaging recess provided in the upper steel pipe, both the steel pipes are rotated and moved. Then, a joint structure is disclosed in which two steel pipes can be connected by engaging the protrusion with an engaging portion further provided in the engaging recess.

JP 2002-256549 A JP-A-9-125376 JP 2001-279665 A Japanese Patent Laid-Open No. 11-21882 JP 2003-90035 A

  However, when connecting steel pipes by on-site welding, the problems are that the welding time is long, the construction period and construction costs are likely to increase due to the weather, etc. It is difficult to ensure reliability.

  Further, in the case of a joint structure by screwing, there is a problem that high accuracy is required when threading the male screw part and the female screw part, and the manufacturing cost is likely to increase as compared with other joint structures. Further, if mud or the like adheres to the male screw portion or the female screw portion, it becomes necessary to perform a joining operation after removing the mud or the like, and there is a problem that the storage management of the steel pipe becomes troublesome. In addition, it is necessary to perform the connection work while accurately aligning the two steel pipes provided with the male screw portion and the female screw portion, which is not preferable from the viewpoint of workability.

  Further, in the case of the joint structure by bolt joining, it is necessary to provide a female screw structure for screwing into the male screw of the bolt. When such a female screw structure is provided, the structure is complicated as in Patent Document 2. There is a problem that the manufacturing cost tends to increase. Further, as shown in Patent Document 3 without providing a female screw structure, a method of using one-side bolts is also conceivable, but if a plurality of expensive one-side bolts are used, the construction cost will eventually increase. There is a point. In addition, depending on the position and angle of the bolt hole, it may be difficult to fasten the bolt and nut on site, which is not preferable from the viewpoint of workability.

  In addition, in the case of a joint structure by fitting, there is a merit that the configuration is simple compared to joining by field welding and other joint structures, and it is superior in terms of workability, construction cost, and manufacturing cost. However, in the case of a joint structure by fitting, for example, as in the techniques disclosed in Patent Literature 4 and Patent Literature 5, a projection provided on one steel pipe is inserted into a groove provided on the other steel pipe. Therefore, when these techniques are applied to a steel pipe having a large diameter, there are problems that the processing accuracy of the groove is likely to be lowered, deviation is likely to occur after the steel pipe is connected, and it is difficult to ensure a predetermined joint strength. In addition, for example, in the technique disclosed in Patent Document 4, it is predicted that it is easy to come off when the direction of rotation or load changes, and the small-range landslide whose application range is hardly changed even in the pile field. There is a problem that it is limited to the prevention pile and cannot be used as a pile foundation such as a support pile.

  Therefore, the present invention has been devised in view of the above-described problems, and the purpose thereof is to eliminate the need for on-site welding, excellent workability, and low manufacturing costs. An object of the present invention is to provide a steel pipe joint structure capable of sufficiently securing the required joint strength.

  In order to solve the above-described problems, the inventor of the present application has invented the following steel pipe joint structure after extensive studies.

  The steel pipe joint structure according to claim 1 of the present invention is a steel pipe joint structure that allows two steel pipes to be connected in the axial direction, and straddles the two steel pipes whose joint end faces at the end portions in the axial direction are butted against each other. The fitting member fitted to the inner peripheral surface of these steel pipes, the outer jigs of the two steel pipes, a plurality of mounting jigs provided in the circumferential direction, and the axial direction of the steel pipe so as to reciprocate a plurality of times. A cord-like body wound around a plurality of mounting jigs in the two steel pipes and wound around the two steel pipes is provided.

  The steel pipe joint structure according to claim 2 of the present application is the invention according to claim 1 of the present application, wherein the joint member is fixedly provided at an end of the one steel pipe and is substantially the same as the inner diameter of the other steel pipe. It is characterized by being formed in a cylindrical shape having an outer diameter.

  The joint structure of the steel pipe according to claim 3 of the present application is the invention according to claim 1 or 2, wherein the joint member has a length protruding from an end of one steel pipe in the previous period of 1. mm of the outer diameter of the steel pipe. It is 0 times or more.

  The joint structure of the steel pipe according to claim 4 of the present invention is the invention according to any one of claims 1 to 3, wherein the joint member is formed in a cylindrical shape and is provided in a plurality in the circumferential direction of the steel pipe. It is characterized by being divided.

  The steel pipe joint structure according to claim 5 of the present invention is the invention according to any one of claims 1 to 4, wherein the mounting jig is spaced so as to equally divide the circumference formed by the outer peripheral surface of the steel pipe. It is characterized by being provided with a gap.

  The joint structure of a steel pipe according to claim 6 of the present invention is the invention according to any one of claims 1 to 5, wherein the cord-like body is provided with male screw portions provided at both ends thereof on the mounting jig. The fixing member is inserted into the insertion hole and fixed to the mounting jig by being screwed into the male screw portions at both ends thereof.

  According to the joint structure of a steel pipe according to claim 1 of the present application, even when a load is applied in any direction of tension, compression, axial torsion, and bending to two connected steel pipes, This makes it possible to sufficiently ensure the required joint strength.

  Further, in the steel pipe joint structure according to the present invention, when two steel pipes are connected, one of the steel pipes is inserted into the joint member, and the cords are stretched over these steel pipes and connected by simple work. The work can be completed, the work of the operator is not affected, and a quick construction is possible, which is very excellent from the viewpoint of workability. In addition, during the connection work, even if the positional relationship of the mounting jig between the two steel pipes to be connected is somewhat shifted, it is possible to easily stretch and wind the cord-like body, There is no need to strictly align the circumferential direction of the two steel pipes, and the construction efficiency can be improved.

  In addition, the steel pipe joint structure according to the present invention has a smaller number of materials as compared with the joint structure by bolt joining, and it is possible to reduce the construction cost and the manufacturing cost. In addition, since there is no need to make the positional relationship of the mounting jig between the two steel pipes to be connected, it has a structure that allows a wide tolerance range for the mounting position of the mounting jig in the manufacturing stage, The burden can be reduced in terms of manufacturing accuracy.

  Moreover, according to the steel pipe joint structure according to claim 2 of the present application, since the joint member is formed in a cylindrical shape having an outer diameter substantially the same as the inner diameter of one steel pipe, the inner peripheral surface of the upper steel pipe It fits in the state which the outer peripheral surface contacted over the perimeter, and high cross-sectional rigidity will be obtained in the connection part of a lower steel pipe and an upper steel pipe. In addition, since the joint member is configured to be fixed to the end of one steel pipe, the joint member can be attached by welding without machining or the like, compared with other conventional joint structures, It is possible to reduce the manufacturing cost.

  Further, according to the joint structure of the steel pipe according to claim 3 of the present application, when the bending tensile load acts on the two steel pipes to be connected, the lever principle acts between the joint member and the two steel pipes. The joint strength required for the connection of two steel pipes can be sufficiently obtained.

  Moreover, according to the steel pipe joint structure according to claim 4 of the present application, the split pieces formed by dividing the joint member can be attached to the inner peripheral surface of the steel pipe one by one, thereby improving workability. it can

  Moreover, according to the joint structure of the steel pipe which concerns on this-application Claim 5, the force which acts on a mounting jig from the cord-like body stretched over two steel pipes becomes equal, and joint strength is exhibited stably. Become.

  Moreover, according to the steel pipe joint structure according to claim 6 of the present application, it is possible to easily perform the work of fixing the cord-like body and the operation of introducing a tensile load into the cord-like body.

  Hereinafter, as a mode for carrying out the present invention, a steel pipe joint structure capable of connecting two steel pipes in the axial direction will be described with reference to the drawings.

  1-4 is a figure which shows an example of the state before and behind connecting the two steel pipes 3 and 4 arrange | positioned perpendicularly at intervals up and down by the steel pipe joint structure 1 to which this invention is applied. FIG. 1 is a perspective view showing a state before connection of two steel pipes 3 and 4 to be connected, and FIG. 2 is a longitudinal side view of FIG. Moreover, FIG. 3 is a perspective view which shows the state after the connection of the two steel pipes 3 and 4 which should be connected, and FIG. 4 is a vertical side view of FIG.

  The two steel pipes 3 and 4 to be connected are steel pipes having substantially the same outer diameter. As shown in FIG. 2, one of the steel pipes 3 has one lower end portion in the axial direction (not shown) embedded in the ground, and the other steel pipe is disposed above the joining end surface 3b in the other upper end portion 3a in the axial direction. The joint end surface 4b in the lower end portion 4a of 2 is abutted and disposed. After connecting the two steel pipes 3 and 4, as shown in FIG. 4, it arrange | positions in the state which the joining end surfaces 3b and 4b which faced each other contact.

  These steel pipes 3 and 4 are used as steel pipe piles. Hereinafter, the steel pipe 3 disposed on the lower side is referred to as the lower steel pipe 3, and the steel pipe 4 disposed on the upper side is referred to as the upper steel pipe 4.

  As shown in FIGS. 3 and 4, the joint structure 1 according to the present invention includes a joint member 5, a mounting jig 7, and a cord-like body 9.

  As shown in FIG. 1, the joint member 5 protrudes upward from the upper end portion 3 a of the lower steel pipe 3. The joint member 5 is composed of a cylindrical steel pipe. The steel pipe constituting the joint member 5 has an outer diameter substantially the same as the inner diameter of the inner peripheral surface of the lower steel pipe 3 and the upper steel pipe 4. Thus, the joint member 5 is fitted to the inner peripheral surfaces of the lower steel pipe 3 and the upper steel pipe 4 in a state where the outer peripheral surfaces are in contact with the entire circumference of the inner peripheral surface of the lower steel pipe 3 and the upper steel pipe 4. It is possible. The lower end side of the joint member 5 is fitted and provided by being inserted into the inner peripheral surface of the lower steel pipe 3. As shown in FIG. 2, the joint member 5 is welded and joined to the inner peripheral surface of the lower steel pipe 3 along the outer peripheral edge 5a on one end side in the axial direction at the manufacturing stage. The outer peripheral surface is weld-joined along the inner peripheral edge 3c of the end portion 3a.

  As shown in FIG. 3, after the lower steel pipe 3 and the upper steel pipe 4 are connected, the joint member 5 is provided by being fitted by being inserted into the inner peripheral surface of the lower end portion 4 a of the upper steel pipe 4. Thus, the lower steel pipe 3 and the upper steel pipe 4 are straddled and fitted to the inner peripheral surfaces of these steel pipes 3 and 4. Thereby, the joint member 5 restrains the radial movement of the lower steel pipe 3 and the upper steel pipe 4 and prevents the lower steel pipe 3 and the upper steel pipe 4 from being misaligned.

  As shown in FIG. 1, the mounting jig 7 is provided on the outer peripheral surface in the vicinity of the upper end portion 3 a of the lower steel pipe 3 and the lower end portion 4 a of the upper steel pipe 4 so as to be spaced apart in the circumferential direction. Yes. FIG. 5A is an enlarged cross-sectional view showing the configuration of the mounting jig 7. As shown in FIGS. 3 and 5A, the attachment jig 7 is provided for hooking and attaching the cord-like body 9. The attachment jig 7 is provided so as to protrude outward from the outer peripheral surfaces of the lower steel pipe 3 and the upper steel pipe 4. In the present embodiment, the mounting jig 7 is made of a steel plate having a predetermined thickness, and has an insertion hole 71 penetrating in the plate thickness direction. The attachment jig 7 is joined to the lower steel pipe 3 and the upper steel pipe 4 by welding.

  FIG. 6 is a plan view of the lower steel pipe 3 showing an arrangement state with respect to the lower steel pipe 3 and the upper steel pipe 4 of the attachment jig 7. As shown in FIG. 6, the mounting jig 7 is arranged with an interval so as to equally divide the circle formed by the outer peripheral surfaces of the lower steel pipe 3 and the upper steel pipe 4. In the present embodiment, the mounting jigs 7 are arranged at intervals so as to divide the circumference formed by the outer peripheral surface of the steel pipe into eight equal parts, and eight mounting jigs are arranged at a 45 ° pitch.

  FIG. 7 is a side view of the lower steel pipe 3 and the upper steel pipe 4 showing a fixing state with respect to the attachment jig 7 at both ends of the cable-like body 9. In the present embodiment, the cord-like body 9 is composed of a wire rope provided with a threaded male thread portion 91 as shown in FIG. 7 by processing both ends in the axial direction. As shown in FIG. 3, the cord-like body 9 is configured to reciprocate the axial direction of the lower steel pipe 3 and the upper steel pipe 4 a plurality of times so that a plurality of the steel pipes 3 and the upper steel pipe 4 are provided. While being stretched around the mounting jig 7, the lower steel pipe 3 and the upper steel pipe 4 are wound in the circumferential direction. In the present embodiment, the cord-like body 9 is attached to the plurality of attachment jigs 7 while being inserted through the insertion holes 71. As shown in FIG. 7, the cable-like body 9 has a female screw that can be screwed into the male screw portion 91 after the male screw portions 91 at both ends in the axial direction are inserted into the insertion holes 71 of the mounting jig 7. The fixing member 93 such as a nut is screwed to fix the fixing member 93 to the lower steel pipe 3 and the upper steel pipe 4. A predetermined tensile load is introduced into the cord-like body 9 by firmly fastening one or both of the fixing members 93 on both sides thereof, whereby the lower steel pipe 3 and the upper steel pipe are introduced. It is possible to resist the pulling force acting on 4 and the force to rotate.

  In the present embodiment, as shown in FIG. 3, the cord-like bodies 9 are alternately stretched over the attachment jig 7 of the lower steel pipe 3 and the upper steel pipe 4 at a 45 ° pitch. Two cord-like bodies 9 are provided so as to be plane-symmetrical at the joint end surfaces 3b and 4b of the three and four.

  Next, an example of a construction procedure for connecting two steel pipes in the axial direction by the steel pipe joint structure 1 as described above will be described.

  As a construction procedure, first, the lower steel pipe 3 is driven to a predetermined depth by an intermediate digging method in which a steel pipe pile is buried in the ground while excavating with an earth auger or the like. Thereafter, the upper end 3 a of the lower steel pipe 3 and the lower end 4 a of the upper steel pipe 4 are disposed so as to abut each other, and the joint member 5 protruding from the upper end 3 a of the lower steel pipe 3 is connected to the upper steel pipe 4. It is inserted and fitted into the inner peripheral surface of the lower end 4a.

  Thereafter, the male thread portion 91 at one end of the cord-like body 9 is inserted into the insertion hole 71 of an appropriate attachment jig 7, and the fixing member 93 is screwed into the insertion hole 71 to be temporarily fixed to the attachment jig 7. Thereafter, as shown in FIG. 3, the cord-like body 9 is provided on the lower steel pipe 3 and the upper steel pipe 4 so as to reciprocate in the axial direction of the lower steel pipe 1 and the upper steel pipe 2 a plurality of times. Further, the lower steel pipe 3 and the upper steel pipe 4 are wound in the circumferential direction while being stretched over the plurality of mounting jigs 7. Thereafter, the male thread portion 91 at the other end of the cord-like body 9 is inserted into the insertion hole 71 of the mounting jig 7, and the fixing member 93 is screwed into this to fix both ends of the cord-like body 9. By tightening any one of the fixing members 93 on both sides of the body 9, a tensile load is introduced into the cable body 9 to tension the cable body 9. Thereby, the lower steel pipe 1 and the upper steel pipe 2 are connected, and the connection work is completed. The present invention can be applied to all embedding methods such as a pre-boring method in addition to the digging method.

  Next, the effect of the steel pipe joint structure 1 having such a configuration will be described.

  FIG. 8A to FIG. 8C are schematic front views showing two steel pipes 3 and 4 connected by the steel pipe joint structure 1 in the present invention. In the steel pipe joint structure 1 according to the present invention, the joint member 5 protruding from the end of one steel pipe 3 is fitted to the other steel pipe 4, and then a plurality of axial directions of the steel pipes 3 and 4 are reciprocated. In addition, a cord-like body 9 is stretched around a plurality of mounting jigs 7 in the respective steel pipes 3 and 4 and is wound around the two steel pipes 3 and 4. As a result, when a tensile load is applied in the direction A that separates the two connected steel pipes 3 and 4 as shown in FIG. 8A, or two steel pipes as shown in FIG. 8B. When a load is applied in the direction B in which the 3 and 4 are rotated, the cable 9 can resist the load. Further, when a bending tensile load is applied in the direction C which is the most problematic on the joint structure as shown in FIG. 8C, the joint member 5 and the cord-like body 9 can resist each other. That is, according to the present invention, even when a load is applied in any of the directions A, B, and C as shown in FIG. 8, the joint member 5 and the cord-like body 9 can resist. Thus, the required joint strength can be sufficiently secured.

  In the steel pipe joint structure 1 according to the present invention, at the time of connecting the two steel pipes 3, 4, one of the steel pipes is inserted into the joint member 5, and the cord-like body 9 is stretched over the steel pipes 3, 4. The connection work can be completed by a simple work that only requires tension, the work of the operator is not incurred, and a quick construction is possible, which is excellent from the viewpoint of workability. Further, at the time of connection work, even when the positional relationship of the mounting jig 7 between the two steel pipes 3 and 4 to be connected is slightly deviated, the cord-like body 9 is easily stretched and wound. Therefore, it is not necessary to strictly align the circumferential positions of the two steel pipes 3 and 4, and the construction efficiency can be improved.

  Further, in the steel pipe joint structure 1 according to the present invention, the number of materials is small as compared with the joint structure by bolt joining, and it is possible to reduce the construction cost and the manufacturing cost. In addition, since it is not necessary to make the positional relationship of the mounting jig 7 between the two steel pipes 3 and 4 to be connected to each other, the structure in which the tolerance range can be widened for the position where the mounting jig is mounted in the manufacturing stage. Therefore, the burden can be reduced in terms of manufacturing accuracy.

  Incidentally, the two connected steel pipes 3 and 4 are arranged in a state in which the joining end faces 3b and 4b that are in contact with each other are in contact with each other. For this reason, it is possible to smoothly transmit the axial load acting in the axial direction of the two steel pipes 3 and 4.

  Further, when the joint member 5 in the present invention is formed in a cylindrical shape having an outer diameter that is substantially the same as the inner diameter of one of the steel pipes 4, the outer peripheral surface thereof extends over the entire circumference of the inner peripheral surface of the upper steel pipe 4. Are fitted in contact with each other, and high cross-sectional rigidity is obtained at the connection portion between the lower steel pipe 3 and the upper steel pipe 4. Moreover, when it is set as the structure which fixes and provides the joint member 5 to the edge part of one steel pipe 4, since the joint member 5 can be set as the structure attached by welding joining, without machining etc., other conventional joint structures Compared to the above, it is possible to reduce the manufacturing cost.

  Each component used for the steel pipe joint structure 1 in the present invention may be configured as follows.

  The steel pipes 3 and 4 to be connected in the axial direction, to which the present invention is applied, are used as, for example, a support pile used as a foundation of a structure, a foundation pile such as a friction pile, and a landslide prevention pile. There is no particular limitation on its use.

  The joint member 5 is not limited to a case where the joint member 5 is composed of a cylindrical steel pipe. However, as described above, the outer diameter of the joint member 5 is substantially the same as the inner diameter of the inner peripheral surfaces of the two steel pipes 3 and 4. The cylindrical steel pipe is preferably fitted over the two steel pipes 3 and 4. The material of the joint member 5 is not limited to steel but may be composed of any of ferrous metals and non-ferrous metals.

  As shown in FIG. 2, the joint member 5 has a longitudinal length L <b> 1 protruding from the joint end surface 3 b at the end 3 a of the lower steel pipe 3, which is 1.0 times or more the outer diameter D of the steel pipe 3. It is preferable. The reason for this will be described.

  When a bending tensile load as in the direction C shown in FIG. 8C is applied to the two steel pipes 3, 4, the stress acting on the connecting portion 2 of the two steel pipes 3, 4 is lower steel pipe 3. The connection part of the two steel pipes 3 and 4 via one end side 5b of the joint member 5 on the side fitted to the upper side and the other end side 5c of the joint member 5 on the side fitted to the upper steel pipe 4 It is transmitted to a place away from 2. Here, assuming that one end side 5b of the joint member 5 is a fulcrum and the other end side 5c is an action point, the longer the other end side 5b of the joint member 5 is, the longer the length of the two steel pipes 3 and 4 is. The stress acting on the connecting portion 2 is reduced and transmitted to the upper steel pipe 4. The inventor of the present application can determine the length of the other end side 5b of the joint member 5 that can sufficiently obtain the joint strength required for the connection portion 2 of the two steel pipes 3, 4, that is, the end portion 3a of the lower steel pipe 3. As a result of intensive research on the length L1 protruding from the length, it was found that the load resistance required for the joint is satisfied if the length L1 is 1.0 times or more. Therefore, the length L1 of the joint member 5 is preferably 1.0 times or more the outer diameter D of the steel pipe 3.

  In addition, as shown in FIG. 2, the longitudinal length L2 in which the joint member 5 is fitted to the lower steel pipe 3 particularly corresponds to the length L1 from the joining end surface 3b in the end portion 3a of the lower steel pipe 3. Even if it does not do, the above effects are exhibited. For this reason, the length L2 of the joint member 5 is not particularly limited, but may be, for example, 0.5 times or more the outer diameter D of the steel pipe 3.

  FIG. 9 is a perspective view showing another configuration of the joint member 5. When the joint member 5 is composed of a cylindrical steel pipe, as shown in FIG. 9, the joint member 5 may be appropriately divided in a plurality in the circumferential direction. In this case, the division | segmentation piece 51 formed by dividing | segmenting the coupling member 5 can be attached to the internal peripheral surface of the steel pipe 1 one by one, and workability can be improved. Moreover, the joint member 53 may attach a reinforcing bar to the inside of the vicinity of the protruded end portion in the circumferential direction, thereby improving the cross-sectional rigidity of the joint member 3.

  The number of the mounting jigs 7 to be arranged depends on the diameters of the lower steel pipe 3 and the upper steel pipe 4, but is not particularly limited, and the interval may be appropriately determined according to the situation in which the cord 9 is wound and fixed. Good. Moreover, although the location which arrange | positions the attachment jig | tool 7 is preferable in the vicinity of the edge part of the steel pipes 3 and 4, it does not specifically limit to this. Further, the mounting jig 7 does not have to be arranged so as to equally divide the circumference formed by the outer peripheral surfaces of the steel pipes 3 and 4 to be connected. The effect of the period is demonstrated. In addition, when the attachment jig 7 is arranged so as to equally divide the circumference formed by the outer peripheral surfaces of the steel pipes 3 and 4, the cable-like body 9 stretched between the two steel pipes 3 and 4 is changed to the attachment jig 7. The acting force becomes uniform, and the joint strength is stably exhibited. In addition, the material of the mounting jig 7 is not limited to steel, and may be made of either ferrous metal or non-ferrous metal.

  The shape of the attachment jig 7 is not particularly limited as long as at least the cord-like body 9 can be hooked and attached. As an example of the shape that the mounting jig 7 can take, there may be mentioned one having an insertion hole 71 for allowing the cord-like body 9 to pass through a member having an arbitrary shape as shown in FIG. In the case of this shape, as long as it is inserted into the insertion hole 71, the cord-like body 9 will not come out, so the attachment work of the cord-like body 9 can be performed reliably.

  FIG. 5B is an enlarged cross-sectional view showing another configuration of the mounting jig 7. As shown in FIG. 5 (b), the mounting jig 7 has an engaging portion 75 protruding from the outer peripheral surface of the steel pipes 3 and 4, and one end side fixed to the engaging portion 75, and is hooked on the engaging portion 75. You may be comprised from the attachment jig | tool 73 formed in the L shape from the retaining part 77 provided in the outer peripheral side of the steel pipes 3 and 4 rather than the cable-shaped body 9 made. An opening 79 is formed between the other end side of the retaining portion 77 and the outer peripheral surface of the steel pipes 1 and 2. In the case of such a configuration, the attachment work can be completed quickly only by hooking the rope-like body 9 to the engaging portion 75 through the opening 79 during the attachment work of the rope-like body 9.

  It is preferable that the cord-like body 9 has a large degree of freedom of deformation and has a strength that does not break when a predetermined tensile load is applied. For example, a single wire such as a metal wire, natural fiber, synthetic fiber, or the like A cord-like thing like a stranded wire is mentioned, and specific examples include a wire rope, a PC (Prestressed Concrete) steel wire, a PC steel stranded wire, and the like.

  The number of the cords 9 used is not particularly limited, and may be only one or three or more, and the number of turns wound around the steel pipes 3 and 4 is also two. It may be more than a circumference and is not particularly limited. Further, the cord-like body 9 does not need to be alternately stretched with respect to the mounting jig 7 of the two steel pipes 3 and 4, and a plurality of the cord-like bodies 9 reciprocate in the axial direction of the steel pipes 1 and 2 under an arbitrary condition. It may be stretched over.

  If the both ends of the cable-like body 9 are fixed to the steel pipes 3 and 4 via a member such as the mounting jig 7 in a state where a predetermined tensile load is introduced, the both ends are attached to the steel pipes 3 and 4. The structure for fixing is not particularly limited. However, from the viewpoint of facilitating the work of fixing the cable-like body 9 and the work of introducing a tensile load into the cable-like body 9, as described above, the cable-like body 9 provided with the male screw portions 91 at both ends thereof is used. It is preferable that the fixing member 93 is screwed into the insertion hole 71 of the mounting jig 7. In the case where it is difficult to attach the fixing member 93 such as a nut by using the attachment jig 73 as shown in FIG. 5B as the attachment jig, the attachment jig shown in FIG. In addition to 73, it is of course possible to provide a mounting jig 7 shown in FIG. 5 (a) in order to easily fix the male thread portion 91 of the cord-like body 9.

  In this example, in order to check the joint strength of the present invention, numerical analysis was performed using the analysis code MARC. FIG. 10 (a) is a diagram showing a state in which two steel pipes 3 and 4 arranged horizontally on the left and right sides are connected by the steel pipe joint structure 1 in the present invention, and FIG. It is a figure shown about length L1, L2 of the coupling member 5 with respect to the steel pipes 3 and 4 arrange | positioned at intervals. In this example, as shown in FIG. 10 (a), a model was constructed in which the axial ends of steel pipes 3 and 4 having a total length of 8 m were connected by the joint structure 1 of the present invention. The values used for modeling are shown in Table 1 below. A wire rope was adopted as the cord-like body 9. Further, eight mounting jigs 7 are arranged in the vicinity of the ends of the two steel pipes 3 and 4 for each of the steel pipes 3 and 4 with an interval of 45 ° in the circumferential direction. The wire ropes as the cord-like bodies 9 are alternately stretched over the mounting jigs 7 of the two steel pipes 3 and 4 at a 45 ° pitch, and are surfaced at the joining end faces 3b and 4b of the two steel pipes 3 and 4. Two were provided so as to be symmetrical. In addition, the friction coefficient of the inner peripheral surface of the steel pipes 3 and 4 in contact with the outer peripheral surface of the joint member 5 was set to 0.2. By constructing such a model, as shown in FIG. 10 (a), a load is applied in the direction indicated by the arrow to the intermediate portion of each steel pipe 3, 4 in the axial direction, and two steel pipes 3 are loaded by four-point loading. 4, a pure bending load was applied to the connection part 2.

  In the above model, the protrusion length L1 of the joint member 5 from the end 3a of one steel pipe 3 as shown in FIG. 10 (b) is 0.5D with respect to the outer diameter D of the steel pipes 3 and 4. The joint strength was verified by changing to three types of 1.0D and 1.5D. In addition, the length L2 fitted to one steel pipe 3 of the joint member 5 was set to 0.5D.

  The joint strength was evaluated by measuring the displacement in the pipe diameter direction of the connecting portion 2 with respect to the bending load applied to the connecting portion 2 of the two steel pipes 3 and 4. FIG. 11 shows the analysis result obtained by the measurement. Note that the yield load in FIG. 11 is a value obtained by converting the yield stress of the steel material into a moment, the allowable load is a value obtained by converting the allowable stress of the steel material into a moment, and the design load resistance is 1 / yield of the yield load. The numerical value of 3 is the required performance required for the joint. Further, the data shown as a steel pipe in FIG. 11 and indicated by a black circle is that the two steel pipes 3 and 4 shown in FIG. 10A are connected by the joint structure 1 according to the present invention, and the total length is 16 m. A bending load is applied to a single steel pipe under the same conditions as described above, and the displacement in the pipe radial direction at a position 8 m from both ends, which is the middle part of the steel pipe, is plotted. The yield stress, allowable stress, outer diameter, etc. of this single steel pipe are the same as the conditions shown in Table 1.

  From the analysis result of FIG. 11, when the protrusion length L1 of the joint member 5 is 0.5D, it was confirmed that the joint strength is slightly lower than the design load resistance. Moreover, when the protrusion length L1 of the joint member 5 was 1.0D, it was confirmed that a joint strength higher than the design load resistance was obtained, and that the bending design load resistance required for the joint was satisfied. Moreover, when the protrusion length L1 of the joint member 5 is 1.5D, it was confirmed that the yield load of the steel pipes 3 and 4 was almost the same, and high joint strength was exhibited. From this result, if the protrusion length L1 of the joint member 5 is secured to 1.0D or more, the lever principle works between the two steel pipes 3 and 4 and the joint member 5, and the bending design load resistance required for the joint It was confirmed that you satisfy.

  In addition, although it is estimated that when the protrusion length L1 of the joint member 5 is longer than 1.5D, the strength against the bending load of the joint portion is further improved, the strength of the joint portion need not exceed the strength of the steel pipes 3 and 4. In the case of this model, the upper limit of the protrusion length L1 of the suitable joint member 5 is about 1.5D. In addition, when the protruding length L1 of the joint member 5 is 0.5D, the joint member 5 and the cord-like body 9 (wire rope) share the bending tensile load: joint member: cord-like body (wire rope) = 7: 3, when the protrusion length L1 of the joint member 5 is 1.0D, the joint member: cord-like body (wire rope) = 8: 2, and when the protrusion length L1 of the joint member 5 is 1.5D, the joint Member: cord-like body (wire rope) = 9: 1, and the result was that the proportion of the load burden on the joint member 5 increased as the length of the joint member 5 increased.

  The disclosed technique described in Patent Document 4 also has the possibility of exhibiting joint strength equivalent to that of the present invention due to the lever principle acting. However, when the joint structure disclosed in Patent Document 1 is manufactured in the same size as the embodiment, it is assumed that the number of projections for connection is increased in order to satisfy the joint strength. The reduction in accuracy increases the processing burden. Also, on the construction surface, it is conceivable that positioning on the site becomes difficult due to an increase in connecting projections, and rattling occurs due to a decrease in processing accuracy. On the other hand, the present invention uses the cable-like body 9 as a connecting material for the two steel pipes 3 and 4, and it is not necessary to strictly determine the connecting positions of the upper and lower steel pipes 3 and 4 in the construction on site. Efficiency can be improved. Moreover, it is a structure that allows a relatively wide allowable error range in terms of construction, and has the effect of reducing the burden in terms of manufacturing accuracy.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. The joint structure in the present invention is not only used as a joint for connecting two steel pipes arranged vertically up and down as described in the above embodiment, but horizontally in the left and right as described in the above example. It is good also as using as a coupling which connects two steel pipes arranged. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

It is a perspective view which shows the state before the connection of the two steel pipes which should be connected. It is a vertical side view which shows the state before the connection of the two steel pipes which should be connected. It is a perspective view which shows the state after connecting two steel pipes which should be connected. It is a vertical side view which shows the state after connecting the two steel pipes which should be connected. It is an expanded sectional view which shows an example of the shape of an attachment jig. It is a top view of the steel pipe for demonstrating the arrangement | positioning state of an attachment jig. It is a side view of the steel pipe for demonstrating the fixing state with respect to the attachment jig of the both ends of a cable-like body. It is a schematic front view for demonstrating the effect of this invention. It is a perspective view for demonstrating the state which divided | segmented the coupling member. It is a figure for demonstrating the analysis model used in order to demonstrate the relationship between the protrusion length of a joint member, and joint strength. It is a figure which shows the relationship between protrusion length L1 of a joint member, and joint strength.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Joint structure 2 Connection part 3 Lower side steel pipe 3a End part 3b Joining end surface 3c Inner peripheral edge 4 Upper steel pipe 4a End part 4b Joining end surface 5 Joint member 5a Outer peripheral edge 5b One end part 5c Other end part 7 Jig 9 Split piece 71 Insertion hole 75 Engagement part 77 Retaining part 79 Opening part 91 Male thread part 93 Fixing member

Claims (6)

In a steel pipe joint structure that allows two steel pipes to be connected in the axial direction,
A joint member fitted to the inner peripheral surface of these steel pipes, straddling the two steel pipes where the joining end faces at the end portions in the axial direction are abutted with each other;
On the outer peripheral surface of the two steel pipes, a plurality of mounting jigs provided in the circumferential direction,
A steel pipe joint structure comprising: a cord-like body wound around a plurality of attachment jigs in the two steel pipes so as to reciprocate in a plurality of axial directions of the steel pipes. 2. The joint member is fixed to an end of the one steel pipe and is formed in a cylindrical shape having an outer diameter substantially the same as the inner diameter of the other steel pipe. The steel pipe joint structure described in 1. 3. The steel pipe joint structure according to claim 1, wherein a length of the joint member protruding from an end of the one steel pipe is 1.0 times or more of an outer diameter of the steel pipe. The steel pipe joint structure according to any one of claims 1 to 3, wherein the joint member is formed in a cylindrical shape and is divided into a plurality of parts in a circumferential direction of the steel pipe. The steel pipe joint according to any one of claims 1 to 4, wherein the mounting jig is provided at an interval so as to equally divide a circumference formed by an outer peripheral surface of the steel pipe. Construction. The cord-like body has male screw portions provided at both ends thereof inserted into insertion holes provided in the mounting jig, and fixing members having female screws are screwed into the male screw portions at both ends. The steel pipe joint structure according to any one of claims 1 to 5, wherein the steel pipe joint structure is fixed to the mounting jig.

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