JP4634919B2 - Tension connector - Google Patents

Description

  The present invention is to transmit tension force to a reinforcing bar during the manufacture of a prestressed concrete column that is centrifugally formed in a state where tension is applied to the reinforcing bar, such as a prestressed concrete pile used to support a building. The present invention relates to a tensioning connector used in a case.

  In general, prestressed concrete pillars are manufactured by installing a rebar rod as a core material in a lower mold and using an end plate attached to one end of the rebar as a fixed plate that seals one end of the lower mold A large-diameter bar inserted through the fixing plate that locks the end plate attached to the other end of the reinforcing bar to the tension plate and seals the other end of the lower mold frame A tension rod is connected to the other end of the reinforcing bar via a tension plate, and the lower mold is filled with ready-mixed concrete. Then, the upper mold is closed, and the tension rod is pulled by an out-of-mold tension machine. This is done by stopping the rod at the towing position with a locking nut or the like, centrifugally molding it in a state where the reinforcing bar is tensioned, and then curing the steam.

  Conventionally, in the production of the prestressed concrete column, it is known to adjust the length by adding or removing tension rods of different lengths in order to cope with the production of prestressed concrete columns of different lengths. (See Patent Document 1).

  In addition, when multiple prestressed concrete pillars are formed at one time using a single formwork, multiple rebars installed in the lower frame are spaced in the series direction. It is generally performed to connect the gap with a tension rod different from the tension rod connected to the tension machine.

Japanese Patent Laid-Open No. 7-24826

  However, in the conventional molding performed by connecting the tension rod to the reinforcing bar, fine cracks may be generated on the surface of the prestressed concrete column obtained. This crack is not so bad as to adversely affect the strength of the prestressed concrete column to be obtained, but is not preferable in appearance. Moreover, this fine crack tends to occur in the vicinity of the base of the node portion of the prestressed concrete pile (node pile) having a shaft portion and a node portion having a diameter larger than that of the shaft portion among the prestressed concrete columns.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to prevent the occurrence of fine cracks that are likely to occur on the surface in the molding of a prestressed concrete column.

  For this purpose, the first aspect of the present invention includes a connection plate disposed at both ends and a plurality of connection rods disposed between both connection plates, and both ends of each connection rod correspond to the corresponding connection. It is attached to the plate at equal intervals on a concentric circle, and it is interposed between the reinforcing rods installed in the formwork and the tension rod pulled by the tension machine when forming the prestressed concrete column. A tension connector characterized by being connectable is provided.

  The second aspect of the present invention includes a connection plate disposed at both ends, and a plurality of connection rods disposed between the connection plates, and each connection rod has a corresponding connection plate at each end. On the other hand, it is mounted on the concentric circles at equal intervals, and when multiple pre-stressed concrete columns are formed, they are connected by interposing between the rebar rods installed in the lower frame with intervals in the series direction. The present invention provides a tension connector characterized in that it is possible.

  The reason for the occurrence of cracks on the surface is not necessarily clear, but that the tension rod is composed of a thick bar material having a large diameter and high rigidity, and that only one point transmits the tension force. It is presumed to be caused.

  For example, when pulling with a tension machine, the concrete column containing the reinforcing bar and the tension rod extend, and the formwork is compressed and contracted. The tension rod contracts and the formwork extends. During steam curing, steam heat is transferred to the formwork, tension rod, concrete, and reinforcing bar with a time lag, and each expands, and whether it is sufficiently cooled during the next molding after demolding depends on the next steam heat. The balance of the thermal expansion state of each part also changes. When a tension rod, which is a thick rod with a large diameter and high rigidity, is directly connected to a tension plate, it is assumed that the balance in the stretched and contracted state is poor, and that it is the cause of the occurrence of the fine cracks. The Another possible cause is that the position of the tension rod deviates from the position of the central axis of the mold, causing vibration during centrifugal molding and propagating to the reinforcing bar or concrete.

  The tension connector of the present invention is formed by connecting the connecting plates at both ends with a plurality of connecting rods arranged concentrically, and the peripheral surface is composed of a plurality of connecting rods arranged at equal intervals. It has become a cylindrical shape. Each connecting rod can be made much thinner than a conventional tension rod, and the position where the tension is transmitted can be dispersed to the position of each connecting rod. For this reason, it is easy to balance in the said expansion | extension and shrinkage | contraction state, and generation | occurrence | production of the crack to the surface of the prestressed concrete pillar obtained can be prevented. Further, since each connecting rod has a relatively small diameter and does not need to have a large weight, even if it is slightly deviated from the center position, it is difficult to cause a large loss of weight balance. Therefore, the occurrence of vibration due to eccentricity is small, which is considered to be effective in preventing the occurrence of cracks.

  An example of the present invention will be described with reference to FIGS.

  FIG. 1 is a partially cutaway plan view showing an example of a prestressed concrete column manufacturing apparatus provided with a tension connector according to an example of the present invention, and FIG. 2 is an enlarged cross-sectional view of the tension connector shown in FIG. 3 is a front view of the connecting plate, FIG. 4 is an exploded sectional view around one connecting plate (right side of FIG. 2), and FIG. 5 is an exploded sectional view around the other connecting plate (left side of FIG. 2). FIG.

  In FIG. 1, reference numeral 1 denotes a mold having an upper mold 2 and a lower mold 3, and both ends thereof are sealed with fixing plates 4 and 5 fixed to both ends of the lower mold 3. .

  In the mold 1, reinforcing bar rods 7 having end plates 6 and 6 attached to both ends are installed. Reinforcing bar 7 has a plurality of main bars (not shown) of a predetermined length arranged in a circular shape, and a hoop bar (not shown) is wound around the outer periphery and joined to form a hook shape. It has become. Both ends of each main bar are usually headed and inserted into and engaged with gourd-shaped fastening holes (not shown) formed in the end plates 6 and 6, respectively. In other words, the fastening hole has a gourd shape that connects two large and small holes. By inserting the end of the main muscle that has been subjected to heading into the large hole and shifting it to the small hole, the fastening hole can be headed around the small hole. The formed head is hooked and locked.

  Tension bolts 8 and 8 are attached to both end plates 6 and 6 so as to protrude in the axial direction of the reinforcing bar 7. A tension bolt 8 protruding from the left end plate 6 in FIG. 1 is inserted into a gourd-shaped engagement hole (not shown) formed in the fixing plate 4 of the mold 1 and the end of the main muscle subjected to the heading process. Are engaged in the same manner as the engagement between the portion and the fastening hole. Further, the tension bolt 8 protruding from the right end plate 6 in FIG. 1 includes a gourd-shaped engagement hole (not shown) formed in the tension plate 9 and the end of the main muscle that has been headed. Are engaged in the same manner as the engagement with the fastening holes.

  A tension rod 11 is connected to the tension plate 9 via a tension connector 10 according to the present invention. That is, the tension connector 10 is interposed between the tension plate 9 and the tension rod 11. One end of the tension rod 11 is connected to the tension connector 10, and the other end side slidably passes through the fixing plate 5 and protrudes outward from the mold 1. The tension rod 11 is connected to a tension machine (not shown) on the outward projecting side and is pulled in the axial direction, and the rebar rod 7 can be tensioned by pulling the tension rod 11. It has become. A locking nut 12 is screwed onto the projecting portion of the tension rod 11 to the outside, and the tension nut 11 is screwed to a position where it comes into contact with the fixing plate 5 while being pulled by a tension machine. Thus, the tension state of the reinforcing bar 7 by the pulling of the tension rod 11 can be maintained even after the connection between the tension rod 11 and the tension machine is released.

  As described above, the prestressed concrete column body is configured by connecting and connecting the reinforcing bar 7, the tension connector 10 and the tension rod 11 in the lower mold 3, and filling the concrete between the both end plates 6, 6, After the upper mold 2 is put on the lower mold 3 and fastened, the tension rod 11 is pulled with a tensioning machine, and the reinforcing bar 7 is tensioned with a locking nut 12 and molded with a centrifugal molding machine. It can be manufactured by steam curing. The tension connector 10 according to the present invention can improve the balance between the expansion and contraction force applied to the reinforcing bar 7 and the concrete, and can improve the quality of the resulting prestressed concrete column, which will be further described below. To do.

  As shown in FIGS. 2 to 5, the tension connector 10 includes left and right disk-shaped connection plates 13 and 14 and a connection bar 15 attached between the connection plates 13 and 14. It has become.

  As shown in FIGS. 3 and 4, the connection plate 13 on the left side in FIG. 2 has a female screw portion (not shown) provided at the center of the tension plate 9 (see FIG. 1). The connecting male threaded portion 16 that is screwed to the outer circumferential portion protrudes, and locking grooves 17 are formed at equal intervals in the circumferential direction at positions on a concentric circle of the peripheral edge. Further, as shown in FIGS. 3 and 5, the connection plate 14 on the right side in FIG. 2 has a connection female screw portion 18 into which the inner end side of the tension rod 11 (see FIG. 1) is screwed. In the same way as the other connecting plate 13, locking grooves 17 are formed at equal intervals in the circumferential direction at concentric positions on the peripheral edge.

  The locking groove 17 is connected from the outer surface side of the connection plates 13 and 14 to the small groove portion 17a having a U-shaped cross section formed by crossing the peripheral edges of the connection plates 13 and 14 in the central axis direction of the connection plates 13 and 14. It is comprised from the large groove part 17b formed by drilling to the intermediate part of the thickness of the plates 13 and 14. FIG. The small groove part 17a becomes what the connection rod 15 fits. Further, the large groove portion 17b is formed by fitting the locking tube material 19 attached to the end portion of the connecting rod 15, and has the same center as that of the bottom portion of the small groove portion 17a having a U-shaped cross section, and the curvature of the bottom portion of the small groove portion 17a. It is formed by drilling with a radius larger than the radius.

  Each of the connecting rods 15 is headed at both ends, and a locking tube member 19 is fitted at the end. A seat portion 20 having an enlarged inner diameter is formed on the outer end side of the locking tube member 19, and a head portion 21 at the end portion of the connecting rod 15 formed by heading is locked to the seat portion 20. ing.

  When the end portion of the connecting rod 15 to which the locking tube material 19 is attached is fitted into the locking groove 17, the inner end surface of the locking tube material 19 is locked to the step portion between the small groove portion 17a and the large groove portion 17b. In this state, the connection bar 15 can be attached between the connection plates 13 and 14. Further, since the locking grooves 17 are formed on the concentric circles of the connection plates 13 and 14 at equal intervals in the circumferential direction, the end portions of the connection rods 15 are respectively connected to the corresponding connection plates 13 and 14. The connecting rods 15 are attached to the concentric circles at equal intervals by being fitted into the locking grooves 17. In addition, on the outer surface side of both connection plates 13, 14, in order to prevent the end of the connection bar 15 to which the locking tube material 19 is attached from coming off the locking groove 17, Donut-shaped presser plates 23 and 23 having openings 22 and 22 corresponding to the connection male screw portion 16 and the connection female screw portion 18 are attached.

  The diameter of the concentric circles where the connecting rods 15 are located is ½ or more of the diameter of the bar-shaped reinforcing bar 7 in order to make it easy to distribute and transmit the expansion and contraction force applied to the reinforcing bar 7 and the concrete. It is preferable to be in a range equal to or smaller than the diameter of the reinforcing bar 7. In addition, it is preferable that the connecting rods 15 have substantially the same number and the same thickness as the main reinforcing bar 7. Specifically, it is preferable that the diameter is within ± 20% of the diameter of the main muscle and the number is within ± 2 to approximate the strength of the connecting bar 15 and the main muscle. By doing in this way, the extension and contraction behavior of the tension connector 10 can be brought close to the behavior of the reinforcing bar rod, and the overall balance can be easily achieved.

  In the usage mode of FIG. 1, it is sufficient that the length of the connecting bar 15 is selected within a range in which the tension rod 11 and the tension plate 9 can be connected. In FIG. 1, the tension rod 11 and the tension plate 9 are connected by one tension connector 10. For example, the connection male screw portion 16 of the connection plate 13 is connected to the connection female screw portion 18 of the connection plate 14. It is also possible to connect the tension rod 11 and the tension plate 9 by connecting a plurality of tension connectors 10 in series.

  FIG. 6 is a cross-sectional view showing another example of the tension connector according to the present invention, and FIG. 7 is a diagram showing an example of a connected state using the tension connector of FIG. 6, the same reference numerals as those in FIGS. 1 to 5 denote the same members.

  The tension connector 10 ′ shown in FIG. 6 uses the connection plate 14 having the connection female screw portions 18 on both the left and right sides, and the tension connector 10 described with reference to FIGS. 1 to 5. It is the same. When the tension connector 10 described above and the tension connector 10 ′ of FIG. 6 are used in combination, as shown in FIG. 7, the tension rod 11 is between the tension connector 10 and the tension connector 10 ′. Another tension rod 24 can be connected to connect between the tension rod 11 and the reinforcing bar 7.

  Next, another use mode of the tension connector according to the present invention will be described with reference to FIG.

  FIG. 8 is a partially cutaway plan view showing an example of a prestressed concrete column manufacturing apparatus provided with a tension connector according to another example of the present invention, and FIG. 9 is a diagram of the tension connector shown in FIG. It is an expanded sectional view. 8 and 9, the same reference numerals as those in FIGS. 1 to 5 denote the same members.

  The prestressed concrete column manufacturing apparatus shown in FIG. 8 is for the case where a plurality of prestressed concrete column bodies are taken, and a plurality (two in the drawing) are spaced within one mold 1. Reinforcing rods 7 and 7 are installed in series. Further, a tension connector 10 ″ according to the present invention is attached between the tension plates 6 and 6 attached to opposite ends of the adjacent reinforcing bar rods 7 and 7, 7 are connected.

  As shown in FIG. 9, the tension connector 10 ″ is the tension described with reference to FIGS. 1 to 5 except that the connection plate 13 having the connection male screw portions 16 on both the left and right sides is used. This is the same as the connection tool 10. That is, the tension connection tool 10 "is screwed into the female thread portions (not shown) provided on the tension plates 6 and 6 facing each other. By doing so, the reinforcing rods 7 and 7 are connected.

  By doing in this way, the tension | tensile_strength connection tool 10 '' can improve the balance of the expansion | extension and contraction force which are added between the reinforcing bar rods 7 and 7. FIG.

  In FIG. 8, a tension rod 11 is directly connected to the tension plate 6 connected to the reinforcing bar 7 on the right side in the drawing, and the tension plate 6 and the tension rod 11 are described with reference to FIG. 1 or FIG. 7. Thus, it is preferable to interpose the tensioning connectors 10 and 10 '. Further, in FIG. 8, when the interval between the reinforcing bar rods 7 and 7 is large, for example, in the order of the tension connector 10 ″ / the tension connector 10 ′ (see FIG. 6) / the tension connector 10 ″. They can be connected or connected in the order of the tension connector 10 (see FIG. 2) / the tension rod 24 (see FIG. 7) / the tension connector 10 (see FIG. 2).

  In the illustrated example, the connecting male screw portion 16 and the connecting female screw portion 18 are used as connecting means for the tension plate 7 and the tension rods 11 and 24 and the tension connectors 10, 10 ′, 10 ″. For these connections, means other than screwing can be used. For example, an appropriate coupling device can be used.

It is a partially notched top view which shows an example of the prestressed concrete column body manufacturing apparatus provided with the connector for tension | tensile_strength which concerns on an example of this invention. It is an expanded sectional view of the connector for tension shown by FIG. It is a front view of a connection board. FIG. 3 is an exploded cross-sectional view around one connection plate (right side in FIG. 2). FIG. 3 is an exploded cross-sectional view around the other connection plate (left side in FIG. 2). It is sectional drawing which shows the other example of the connector for tension | tensile_strength which concerns on this invention. It is a figure which shows an example of the connection state using the connection tool for tension | tensile_strength of FIG. It is a partially notched top view which shows an example of the prestressed concrete column body manufacturing apparatus provided with the tension connector which concerns on the other example of this invention. It is an expanded sectional view of the connector for tension shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold frame 2 Upper mold frame 3 Lower mold frame 4 Fixing plate 5 Fixing plate 6 End plate 7 Reinforcement rod 8 Tension bolt 9 Tension plate 10 Tension connector 10 'Tension connector 10 "Tension connector 11 Tension rod 12 Locking nut 13 Connection plate 14 Connection plate 15 Connection rod 16 Connection male screw portion 17 Locking groove 17a Small groove portion 17b Large groove portion 18 Connection female screw portion 19 Locking tube material 20 Seat portion 21 Head portion 22 Opening portion 23 Presser plate 24 Tension rod

Claims (5)

  It is provided with connecting plates arranged at both ends and a plurality of connecting rods arranged between both connecting plates, and both end portions of each connecting rod are equidistantly arranged on concentric circles with respect to the corresponding connecting plates, respectively. A tension that is attached and can be connected between a rebar rod installed in a formwork and a tension rod pulled by a tension machine when forming a prestressed concrete column. Connection tool.   2. The tension according to claim 1, wherein one connection plate is connectable with a tension rod, and the other connection plate is connectable with a tension plate attached to an end of the reinforcing bar on the tension rod side. Connection jig.   It is provided with connecting plates arranged at both ends and a plurality of connecting rods arranged between both connecting plates, and both end portions of each connecting rod are equidistantly arranged on concentric circles with respect to the corresponding connecting plates, respectively. A tension that is attached and can be connected by interposing between a plurality of reinforcing bar rods installed in the lower frame at intervals in the series direction when forming a plurality of prestressed concrete columns. Connection tool.   4. The tension connector according to claim 3, wherein one of the connection plates and the other of the connection plates can be connected to tension plates attached to opposite ends of adjacent reinforcing bar rods, respectively.   The tension connector according to any one of claims 1 to 4, wherein a plurality of tension connectors can be connected in series.

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