JP5860433B2 - PC steel support for PRC bridge girder - Google Patents

Description

  The present invention relates to a support for PC steel used for constructing a PRC bridge girder.

  In Patent Document 1, a box girder is assembled with steel plates, and a PC steel material formed by inserting a plurality of high-tensile steel wires into a sheath is stretched in the span direction in the box girder. A method of constructing a bridge girder that imparts prestress (compressive force) to concrete by tensioning is disclosed. In this method, the PC steel material is placed and supported on one of the webs forming the both side walls of the box girder on a cantilever rack provided horizontally from the inner surface toward the other web.

  Racks are arranged in several rows in the span direction, and PC steel is placed on the appropriate rack. In Patent Document 1, the PC steel is bowed so as to be close to the bottom plate of the box girder in the center of the span. Curved and stretched.

JP 2003-138520 A

  Patent Document 1 discloses a method of constructing a bridge girder by combining a box girder (steel girder) made of a steel plate, concrete, and PC steel, and is a PRC that is a combination of reinforcing bar, concrete, and PC steel. It does not disclose how to construct a bridge girder. That is, since there is no member corresponding to the web of Patent Document 1 in the PRC bridge girder, the rack structure cannot be adopted.

  Moreover, in a cantilevered rack like patent document 1, there exists a possibility that a front end side may bend below by the load of PC steel materials, and lack stability.

  An object of the present invention is to disclose a technique capable of stably supporting a PC steel material when constructing a PRC bridge girder.

  In order to achieve the above-mentioned object, in the present invention, in the PRC bridge girder constructed by arranging the PC steel material in the bridge axis direction between the left and right vertical bars of the stirrup arranged to surround the main axis in the bridge axis direction, As a metal fitting used to support the PC steel material before placing concrete, a steel plate frame provided with a horizontal plate portion at the lower ends of a pair of left and right side plate portions, and a steel rod bridged between the side plate portions The frame includes the horizontal plate portion disposed on the lower rebar of the main reinforcing bar or its assembly reinforcing bar, and the pair of side plate portions fixed to the left and right vertical bars of the stirrup. Use the means to do.

  In the support device of the present invention, the horizontal plate portion functions as an installation base of the frame as positioning until the side plate portion is fixed to the vertical stirrup of the stirrup. And since a side-plate part functions as a leg part which spans a shelf material and supports both ends of a shelf material with a pair of left and right side-plate parts, sufficient load resistance is obtained.

  In the present invention, the frame includes an integral type and a divided type. That is, the integrated frame is formed by connecting a pair of left and right side plate portions with one horizontal plate portion, and forms a U-shaped frame that is open at the top when viewed from the front. According to this frame, since the distance between the side plate portions is kept constant by the horizontal plate portion, the construction is easy. Further, since the horizontal plate portion exists between the side plate portions, the stability at the time of arrangement is increased.

  On the other hand, the split frame includes a pair of left and right L-shaped split frames in which a horizontal plate is provided at the lower end of the side plate. Then, the side plate portions of each divided frame are fixed to the left and right vertical stripes of the stirrup by binding or the like so that the horizontal plate portions face each other. The function of the horizontal plate portion as the installation base in each divided frame is not different from that of the integrated frame, but each can be arranged independently, so that the applicability to the site is enhanced. That is, the main reinforcement (lower rebar) and the assembly reinforcement that arrange the horizontal plate portion are usually arranged in pairs, but the interval between the two differs depending on the scale of the bridge girder. For this reason, the left and right intervals of the stirrup vertical bars that fix the side plate portions also differ on site, but if it is a divided type frame, it can be arranged by adjusting the intervals of the divided frames according to such bar arrangement intervals. it can. In addition, a large number of supports according to the present invention are arranged in the direction of the bridge axis. However, the split type frame can shorten the steel plate length of the horizontal plate portion compared to the integral type frame, so the material cost per support is also reduced. can do.

  It should be noted that the integrated frame and the split frame can be used together at the same site, such as using the integrated frame in one span and using the split frame in other spans.

  In the case of an integrated frame, it is conceivable that the shelf material is provided integrally on the side plate portion from the beginning, but in both the integrated type and divided type frames, through holes are provided in the pair of side plate portions. If a steel bar shelf is inserted and bridged, the support can be configured more easily. In this case, it is preferable to provide a bent portion for preventing the steel rod from coming off at one end.

  Moreover, the height of the shelf member can be changed by providing a plurality of through holes in the pair of side plate portions in the vertical direction. Further, a plurality of shelf members can be provided on the upper and lower sides.

  By the way, when inserting a steel rod shelf into the through hole in the side plate, the shelf must be inserted horizontally, but if the side plate has a large interval and the through hole is separated, it depends on the weight of the shelf. It becomes difficult to insert horizontally. Moreover, when constructing a hollow floor slab bridge with a cylindrical frame, the cover of the stirrup and the cylindrical frame may be small, and it may not be possible to secure a space for inserting the shelf material to the side of the side plate part. Therefore, in order to be able to bridge both ends of the shelf material from the front of the frame to the through holes of the side plate portion at the same time, in the present invention, the pair of side plate portions is further on one side from the through holes obliquely upward. A means of providing a shelf-receiving slit that opens at the edge is used. In this case, it is preferable that the shelf material further has a bent portion at the other end of the steel bar. This is because the shelf material can be prevented from coming out of the side plate portion in the rod axis direction.

  The above-mentioned slits for receiving the shelf material can be provided on both of the pair of side plate portions, so that when the vibration or impact is applied to the support, one end of the shelf material and, in the worst case, both ends are slit. It is assumed that you will get out of. In particular, when the depth of the slit is shallow or the inclination angle is small, the risk increases. Such a drop-out cannot be prevented by the bent portions at both ends of the shelf material. Therefore, in the present invention, means for selectively providing a shelf receiving slit in one of the pair of side plate portions and providing a simple through hole in the other side plate portion is selectively used.

  In this case, it is easy to insert one end of the shelf material into the through hole of the other side plate portion from the inside, rotate the through hole as a fulcrum, and engage the other end side with the shelf material receiving slit. Therefore, a round steel bar having bent portions at both ends is used.

  On the other hand, the frame can be configured by bending a single steel plate. However, the side plate portion needs to be considerably longer than the horizontal plate portion in accordance with the arrangement height of the PC steel material. When the frame is a frame, when the other side plate portion is bent after the one side plate portion is bent, or when the side plate portion is simultaneously bent, the end portions of the side plate portions interfere with each other so that a sufficient bending angle is obtained. It may not be secured. Therefore, in the present invention, a means is used in which a steel plate is divided by a horizontal plate portion and a pair of side plate portions, and these are joined by welding to constitute a frame. However, it does not exclude that the integrated frame is formed by bending. In other words, the joint between the side plate portion and the horizontal plate portion may be either welding or bending.

  Moreover, when many PC steel materials are mounted on the same shelf material, or when the space | interval of a side-plate part is large, there exists a possibility that a shelf material may bend below in the center. Therefore, especially for the integrated frame, an auxiliary steel plate is erected from the center of the horizontal plate portion, and through holes are formed in the auxiliary steel plate so that the shelf material is supported at three points, both ends and the center.

  In the present invention, PC steel means a tension material that gives prestress to concrete, and a PC steel wire, a PC steel rod and a PC steel wire, or a PC steel wire and a PC steel wire are inserted into a sheath. This is the case.

  The PRC bridge girder to be applied is typically a box girder bridge or a hollow floor slab bridge, but is not limited to these bridge girder. Further, the PC steel material may be either post-tension or pre-tension, and the concrete may be precast as well as cast in place.

  According to the support of the present invention, when a PRC bridge girder is constructed, it can be arranged using a reinforcing bar, and can support a PC steel while maintaining sufficient load resistance and stability.

The perspective view of the support tool which concerns on 1st embodiment of this invention. Explanatory diagram for constructing a frame from a single steel plate The side view of the support (frame) which concerns on 2nd embodiment of this invention. Same front view The perspective view of the support tool which concerns on 3rd embodiment of this invention. Explanatory drawing which showed the method of spanning shelf materials in the same support Front view of a support according to a fourth embodiment of the present invention Explanatory drawing which showed the point which fixes the support tool of this invention to the reinforcement of a PRC bridge girder Front view of Fig. 8 viewed in the direction of the bridge axis Explanatory drawing of the support tool which concerns on 5th embodiment of this invention. Explanatory drawing which showed the relationship between the shelf material height of the support tool of this invention, and the extending aspect of PC steel materials Explanatory drawing which shows the inconvenience of using the support tool which concerns on the integrated frame of this invention upside down

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a first embodiment of a support according to the present invention, in which a steel plate frame 1 having side plate portions 1b and 1b erected at both ends of a horizontal plate portion 1a having an appropriate width, and the side plate portions 1b and 1b. And a shelf 2 that spans the wall. In the case of this embodiment, the shelf 2 is made of a steel bar, and the side plate portions 1b and 1b of the frame 1 are provided with through holes 1c and 1c through which the shelf 2 is inserted at appropriate height positions. Yes. Therefore, the shelf 2 is horizontally inserted between the side plates 1b and 1b by inserting the shelf 2 into the through hole 1c from the side of the one side plate 1b and passing through the through hole 1c of the other side plate 1b. Can pass. And although the PC steel material K is mounted on the shelf material 2, since both ends of the shelf material 2 are supported by the through holes, the PC steel material K can be supported with sufficient load resistance.

  In addition, when the shelf 2 is inserted into the through holes 1c and 1c, it is preferable to provide a bent portion 2a at one end (terminal) so that the shelf 2 does not slip out to the opposite side. Although the shelf 2 is made of a round steel bar, it may be made of a square steel bar. In this case, the through hole 1c can be changed from a round hole to a square hole.

  In this embodiment, when the frame 1 is configured, the horizontal plate portion 1a and the side plate portions 1b and 1b made of different steel plates are joined and integrated by the welded joint 3. In order to obtain a frame having the same shape by bending a single steel plate, the side plate portions 1b and 1b are arranged at an upright angle (as shown in FIG. In the case of this embodiment, it is necessary to bend excessively inward beyond 90 degrees, and depending on the length of the side plate portions 1b and 1b, the tips may interfere with each other at the time of bending, and in the first place, This is because the bending angle may not be ensured. However, the joint integration by the welded joint 3 is a preferred configuration method of the frame 1, and in the present invention, the frame 1 obtained by bending a steel plate is not excluded.

  FIG. 3 shows a support according to the second embodiment. Explaining the difference from the first embodiment, the through-hole 1c has a shelf-receiving slit 1d that opens at a side edge on the front side of the side plate portion 1b obliquely upward. Therefore, the shelf material 2 can be bridged from the front side of the frame 1 to the through hole 1c through the slit 1d. This is because the target PRC bridge girder is a hollow floor slab bridge, and the frame 1 is arranged close to the cylindrical frame R, so that a space for inserting the shelf material 2 from the side is secured to the side of the side plate portion 1b. It is effective when it is not possible.

  Further, since the slit 1d is inclined so that the through hole 1c is at the bottom, the shelf material 2 is difficult to come out to the front side. At the same time, as shown in FIG. 4, the shelf material 2 is provided with bent portions 2 a at both ends, so that the shelf material 2 has a high retaining effect.

  Furthermore, the through holes 1c can be provided at a plurality of positions on the upper and lower sides of the side plate portion 1b. Thus, if it is the flame | frame 1 provided with two or more through-holes 1c, the spanning height of the shelf material 2, ie, the PC steel material K, can be supported by desired height.

  FIG. 5 shows a third embodiment of the present invention. In this embodiment, a structure for spanning the shelf 2 with respect to the frame 1 is configured by combining the through hole 1c and the shelf receiving slit 1d described in the first and second embodiments. That is, of the pair of side plate portions 1b and 1b, one side plate portion 1b is provided with the through hole 1c of the first embodiment, and the other side plate portion 1b is provided with the shelf receiving slit 1d of the second embodiment. ing.

  On the other hand, the structure of the shelf 2 is the same as that of the second embodiment, and the bent portions 2a are provided at both ends of the round steel bar. Then, as shown in FIG. 6, the shelf member 2 has a bent portion 2a at one end with the bent portions 2a and 2a facing upward, and an inner side of the through hole 1c of one side plate portion 1b shown in a cross section in FIG. , And the shelf 2 is rotated around the through hole 1c as a fulcrum, and is engaged with the slit 1d of the other side plate portion 1b from above, so that the frame 1 can be bridged. The bent portions 2a and 2a face downward due to their own weight.

  Even if the shelf 2 spanned in this way has no insertion space on the side of the frame 1, the shelf 2 can be spanned from the front side of the frame 1, and the bent portions 2a and 2a at both ends can be provided. Thus, the axial direction can be prevented from coming out. In addition, since the shelf 2 is stretched over the frame 1 and the bent portion 2a at one end protrudes outside the through hole 1c, the horizontal axis of the round steel bar is constrained by the through hole 1c, and the shelf 2 2 does not rotate, and as a result, the other end does not come out of the slit 1d.

  In the two embodiments described above, up to several PC steels K can be supported, but depending on the scale of the bridge girder, it may be necessary to support ten or more PC steels K, as in the above embodiment. If both ends are supported, the shelf 2 is bent at the center, and the PC steel K may not be supported at an appropriate height. Therefore, as a fourth embodiment, as shown in FIG. 7, it is effective to additionally provide an auxiliary steel plate 4 in the middle of the horizontal plate portion 1a and to form a support hole 4a in the auxiliary steel plate 4 as well. It is. According to the fourth embodiment, since the intermediate portion where the shelf material 2 is most easily bent by the weight is reinforced by the auxiliary steel plate 4, more PC steel materials K can be supported.

  FIG. 8 shows a procedure for arranging the support S (the first embodiment) of the present invention with respect to the reinforcing bars of the PRC bridge girder. That is, the PRC bridge girder has a basic reinforcing bar structure in which two main bars 5 are arranged in the upper and lower directions in the bridge axis direction, and the stirrup 6 is arranged around the main bars 5. 7 is a spacer disposed on the lower floor slab, 8 is an assembly bar (also called a set-up bar or a discarded bar) disposed on the spacer 7, 9 is a transverse reinforcing bar disposed on the assembly bar 8, and 10 is a slur. It is an axial rebar arranged in the abdomen of the wrap 6.

  With respect to the reinforcing bar having such a bar arrangement structure, the support S of the present invention arranges the horizontal plate part 1a on the lower reinforcing bar of the main reinforcing bar 5 and fixes the side plate part 1b. Each 1b is fixed by binding to the left and right vertical stripes 6a and 6a of the stirrup 6. The horizontal plate portion 1a can also be disposed on the assembly bar 8. By fixing a plurality of the support tools S at appropriate intervals in this manner, the PC steel material K can be stretched in the bridge axis direction while being positioned inside the stirrup 6.

  FIG. 8 shows a state in which the side plate portions 1 b and 1 b of the frame 1 are positioned inside the vertical bars 6 a and 6 a of the stirrup 6. However, when the interval between the vertical stripes 6a and 6a is narrower than that shown in the drawing, the side plate portions 1b and 1b are positioned on the outer side. As described above, whether the side plate portions 1b and 1b are located inside or outside the longitudinal bars 6a and 6a depends on the dimensional relationship between the frame 1 and the stirrup 6, and the present invention is not limited to any one of them. Absent.

  In this regard, when the axial rebar 10 is placed inside the abdomen of the vertical bars 6a and 6a of the stirrup 6, as shown in FIG. 9, the pair of left and right side plate parts 1b and 1b are further pivoted on the inside. By disposing the frame 1 so as to be inscribed in the directional reinforcing bars 10, the left and right movements of the side plate portions 1 b and 1 b are restricted by the axial reinforcing bars 10, so that the frame 1 can be attached stably. Reference numeral 11 denotes a binding wire such as a wire, which fixes the side plate portions 1b and 1b to the longitudinal bars 6a and 6a, and may be bound to the axial rebar 10 depending on the length of the side plate portion 1b. it can. Such bundling is preferably employed as appropriate for the horizontal plate portion 1a and the main reinforcement 5 or the assembly reinforcement 8. This support tool is not a structural member of a bridge girder in terms of structural strength, but can securely support the PC steel material K by securely fixing the frame 1 to the reinforcing bar.

  By the way, in an actual site, the interval between the vertical bars 6a and 6a of the stirrup 6 varies depending on the size of the PRC bridge girder. Therefore, as in the first to fourth embodiments described above, in the frame 1 (integrated frame) in which the pair of side plate portions 1b and 1b and the horizontal plate portion 1a are integrated, the distance between the side plate portions 1b and 1b is horizontal. Since it is held constant by the plate portion 1a, there may be a case where the arrangement form as shown in FIG. 9 cannot always be obtained.

  In general, the main bars 5 and the stirrup 6 use the spacers 7 and the assembly bars 8 to secure the positions specified in the design drawing. The frame 1 of the present invention allows the horizontal plate portion 1a to be arranged on the assembly bar 8 when the arrangement of the horizontal plate portion 1a on the main bar 5 affects the strength and structure of the bridge girder. The assembling bar 8 arranges the main bar 5 while ensuring the cover thickness, and is often not described in the design drawing, and is appropriately provided at the site. In other words, if the horizontal plate portion 1a is arranged on the main reinforcement 5, an appropriate frame 1 can be prepared by checking the design drawing in advance. There is a problem that the bar arrangement mode cannot be confirmed.

  Therefore, in the present invention, the divided type frame shown in FIG. 10 is used as the fifth embodiment. This split frame is composed of two L-shaped split frames 1A and 1B each having a horizontal plate 1a and 1a at the lower end of each of the left and right side plate portions 1b and 1b. And it arrange | positions so that a mutual horizontal board part 1a * 1a may oppose with respect to a reinforcing bar. That is, also in this divided frame, the horizontal plate portions 1a and 1a are arranged on the main bar 5 or the assembly bar 8 as the installation base, and the side plate portions 1b and 1b are connected to the vertical bars 6a and 6a of the stirrup 6 with the binding wires 11 and the like. However, since the divided frames 1A and 1B are independent, it is possible to deal with bar arrangement at any interval.

  In the split frame, the same configuration as that of the integral frame can be adopted for the shelf material and the through-holes and slits spanning the shelf material. In addition, the method of forming the frame is simple by bending a single steel plate into an L-shape to form each of the divided frames 1A and 1B, but depending on the thickness of the steel plate, In some cases, it is advantageous to obtain separate frames by welding separate steel plates at the portion 1a and the side plate portion 1b, and the present invention includes both. Furthermore, it is not excluded from the present invention to obtain a pair of left and right divided frames by cutting the horizontal plate portion of the integrated frame. Conversely, the integrated frame may be formed by bending one of the left and right side plate portions, and the other side plate portion may be provided by welding. In other words, a steel plate having a predetermined length is bent into an L shape, and another steel plate (a portion corresponding to one side plate portion later) is welded to one end of the portion corresponding to the horizontal plate portion. An integral frame is also within the scope of the present invention.

  And in the 1st to 5th embodiment mentioned above, if the height of the shelf 2 is the same in all the supports S, the PC steel K is stretched horizontally, but the height of the shelf 2 is increased. By changing, as shown in FIG. 11, it is also possible to stretch the PC steel material K like a bow.

  On the other hand, the support tool of the present invention can be stably fixed by fixing the horizontal plate portion 1a on the lower side to the reinforcing bar in the manner described above. Conversely, as shown in FIG. 12, when the horizontal plate 1a in the integrated frame is set to the upper side and the open ends of the side plate portions 1b and 1b are set to the lower side, If the end portion cannot be placed on the lower main reinforcement 5 or the assembly reinforcement 8 and is placed on the spacer 7, the spacer 7 may be destroyed by a load, and stable fixation cannot be expected. The same can be said for divided frames.

DESCRIPTION OF SYMBOLS 1 Steel plate frame 1a Horizontal flat plate part 1b Side plate part 1c Through-hole 1d Slit 2 Shelf material 2a Bending part 3 Welding (part)
4 Auxiliary Steel 5 Main Bar 6 Stirrup 6a Left and Right Vertical Bar 7 Spacer 8 Assembly Bar K PC Steel R Cylindrical Frame S Supporting Tool of the Present Invention

Claims (9)

A support tool for the PC steel material in a PRC bridge girder constructed by arranging a PC steel material in the bridge axis direction between the left and right vertical bars of the stirrup arranged surrounding the main reinforcement in the bridge axis direction,
A steel plate frame provided with a horizontal plate at the lower ends of the pair of left and right side plates;
Comprising a steel bar shelf spanning between the side plate portions,
The frame is characterized in that the horizontal plate portion is disposed on a lower rebar of the main reinforcing bar or an assembly reinforcing bar thereof, and the pair of side plate portions are fixed to the left and right vertical bars of the stirrup. PC steel support. The PC steel material support tool according to claim 1, wherein the frame is formed by connecting a pair of left and right side plate portions with a horizontal plate portion. The frame is provided with a pair of left and right L-shaped divided frames having a horizontal plate portion at the lower end of the side plate portion, and the side plate portions of each divided frame are placed in the left and right vertical directions of the stirrup so that the horizontal plate portions face each other The PC steel material support according to claim 1, which is fixed to each of the bars. 4. The support for PC steel material according to claim 1, 2 or 3, wherein the shelf material is provided with a bent portion for retaining the steel rod at one end, and a pair of side plate portions is provided with a through hole through which the steel rod is inserted. . The support member for PC steel according to claim 4, wherein a plurality of through holes are provided in the pair of side plate portions in the vertical direction. The shelf is further provided with a bent portion at the other end of the steel bar, and at least one side plate is further provided with a slit for receiving the shelf that opens obliquely upward from the through hole to one side edge. Item 6. The support for PC steel according to Item 4 or 5. While only one of the pair of side plate portions is provided with a slit for receiving the shelf material, the shelf material is provided with bent portions at both ends of the round steel rod, and the shelf material has one end as a through hole in the other side plate portion. The PC steel material support tool according to claim 6, wherein the PC steel material support is inserted from the inside, rotated around the through hole as a fulcrum, and the other end side is engaged with the shelf material receiving slit. The auxiliary steel plate is erected from the center of the horizontal plate portion, and the auxiliary steel plate is also provided with a through hole for the shelf material or a slit for receiving the shelf material. PC steel support. The support member for a PC steel material according to any one of claims 1 to 8, wherein the horizontal plate portion and the side plate portion are joined by welding.

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