JP2019052424A - JOINT STRUCTURE OF PCa SLAB AND ITS CONSTRUCTION METHOD - Google Patents

Abstract

To provide a joint structure of a PCa slab capable of shortening a width (dimension) of a filling part while suppressing a brittle fracture form in which cover concrete is extruded, and a construction method thereof.SOLUTION: A joint structure 1 of a PCa slab to be integrated by placing concrete in a filling part for connecting the PCa slabs to each other, comprises: a plurality of joint reinforcements 3, 4 extending in upper and lower stages, in which top reinforcements and bottom reinforcements of main reinforcements of the PCa slab are extended to the filling part; and a plurality of lateral reinforcements 5 extending in upper and lower stages and arranged to be orthogonal to the plurality of joint reinforcements 3, 4 in the filling part 2. Enlarged diameter parts 3a, 4a enlarged in diameter are formed at end parts of the plurality of joint reinforcements 3, 4, and a cover concrete peeling-inhibiting reinforcement member 6 for preventing peeling of the cover concrete on an opened surface of the filling part 2 caused by pushing with a stress acting on the joint reinforcements 3, 4 is arranged on an outer side in the vertical direction of the opened surface side of the top reinforcements and the bottom reinforcements of the plurality of joint reinforcements 3, 4 and inside the enlarged diameter parts 3a, 4a.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a joint structure of a PCa plate, which is a plate-like precast member, and a construction method thereof.

  Conventionally, a pier structure is constructed in a harbor or the like using a PCa (precast) member which is a reinforced concrete structure manufactured in advance in a factory or the like.

  For example, Patent Document 1 discloses a PCa girder member that is installed between steel pipe piles that are erected at a predetermined interval, and is disposed on a straight beam main body and a part of the main body. The socket part is provided below the main body so as to have its top surface flush with the bottom surface of the main body, and the socket part. A PCa girder member is disclosed in which a latching portion that is horizontally projected from the main body and is suspended from the top of the steel pipe pile is disposed above (see Claims of Patent Document 1). Claim 1, paragraphs [0018] to [0027] of the specification, and FIGS.

  On the other hand, a PCa (precast) floor slab, which is a plate-shaped reinforced concrete structure, is manufactured in advance at a factory or the like as a bridge floor slab, and the PCa floor slab is transported to a construction site, and a plurality of PCa floor slabs are arranged at predetermined intervals. A plurality of PCa floor slabs are integrated by laying them apart and constructing a joint structure in the separated spaces.

  For example, in Patent Document 2, the upper and lower reinforcing bars of the bridge axis direction reinforcing bars, which are the main reinforcing bars of the PCa floor slab, proposed by the present applicants are projected as joint reinforcing bars from the end of the floor slab, respectively. A joint structure of a PCa floor slab is disclosed in which a diameter-enlarged portion that is larger than the diameter of the reinforcing bar in the axial direction of the bridge is provided by fitting a crimping grip or the like to the end of the bridge (Patent Document 2 claims) (See claim 1 of the scope, paragraphs [0016] to [0024] of the specification, FIGS. 5 and 6 of the drawings, etc.).

  Therefore, the joint structure of the PCa floor slab having the joint reinforcing bar formed with the enlarged diameter portion such as the crimping grip described in Patent Document 2 is applied to the pier structure as shown in Patent Document 1 to the steel pipe pile. It is also conceivable to cover the steel girders with a jacket, place PCa floor slabs on these steel girders, and integrate the steel girders and PCa floor slabs with the joint structure of PCa floor slabs described in Patent Document 2. .

  However, in the joint structure of the PCa floor slab described in Patent Document 2, the joint length of the joint reinforcing bar is required to be 15 times or more the nominal diameter of the reinforcing steel bar. There has been a problem that the width of the padding portion for integrating the PCa floor slabs of the present invention becomes large. For this reason, the flange width required for the bottom plate of the padding portion becomes larger than the flange width of the steel beam necessary for strength, which is uneconomical. Therefore, when the PCa floor slab is applied to the jetty structure, it is required to reduce the size of the padding portion as much as possible.

  Moreover, even when the joint structure of the PCa floor slab described in Patent Document 2 is applied as a normal bridge floor slab, there is a similar demand. In other words, when using a bridge as a road bridge, etc. (shared) and updating one half on each side, the width of the padding part is reduced as much as possible to reduce the amount of on-site concrete and early-strength concrete etc. There was a request to shorten the construction period such as using it.

  The joint length of the joint rebar described above is required to be at least 15 times the nominal diameter of the rebar because of the stress acting on the joint rebar with the expanded portion due to the bending rigidity of the rebar from the verification experiment etc. This is because the length is set to suppress the brittle fracture mode in which the cover concrete of the interstitial concrete is extruded and peeled off due to a phenomenon close to the Dowel action.

  Further, in Patent Document 3, the lower joint reinforcing bar and the upper reinforcing bar (28) are formed from a lower reinforcing bar (27) and an upper reinforcing bar (28), which are bent from one reinforcing bar and folded at the end of the U-shape. A joint structure of a PCa floor slab surrounded from the joint reinforcement bars is disclosed.

  However, the lower reinforcing bar (27) and the upper reinforcing bar (28) in the joint structure of the PCa floor slab described in Patent Document 3 suppress the occurrence of cracks in the concrete, and the amount of rebar assembling work on the site and the concrete placement It was provided for the purpose of reducing the amount. For this reason, even if it says that the amount of concrete placement is reduced, the lower reinforcing bar (27) and the upper reinforcing bar (28) are not necessarily recessed in the joint end face (12A) and the second joint end face (12B). Since it can be placed at a predetermined position, it is possible to reduce the amount of on-site concrete placement (see paragraph [0057], etc. of Patent Document 3), and the width (dimensions) of the padding portion can be reduced. It was not a thing.

  The reason is that the lower reinforcing bar (27) and the upper reinforcing bar (28) having the same diameter as that of the transverse reinforcing bar arranged perpendicular to the bridge axial reinforcing bar protruding from the PCa floor slab as the connecting reinforcing bar in the padding portion. This is because the first extension part (27C) and the second extension part (28C), which are the fixing lengths of the steel, are required to be 15 times or more of the nominal diameter of the reinforcing bar in accordance with the specification of the road bridge specification. That is, it is because the joint length of the joint rebar which is required 15 times or more the nominal diameter of the above-mentioned rebar cannot be reduced, and the width (dimension) of the padding portion is not reduced (see FIG. 12).

  Moreover, in the joint structure of the PCa floor slab described in Patent Document 3, the lower joint reinforcing bar and the upper joint reinforcing bar are surrounded and restrained by the lower reinforcing bar (27) and the upper reinforcing bar (28), and cracking of the concrete occurs. It is said to suppress. However, in the first place, if the joint structure is an appropriate joint structure such as the joint structure of PCa floor slabs described in Patent Document 2, the concrete does not crack, and no reinforcing bars for crack prevention are required.

JP 2007-77575 A JP 2012-62664 A JP 2017-106231 A

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is to reduce the width of the padding portion while suppressing the brittle fracture mode in which the cover concrete is extruded and peeled off. It is an object to provide a joint structure of PCa plate capable of shortening (dimension) and a construction method thereof.

  The joint structure of PCa plates according to claim 1 is a joint structure of PCa plates in which concrete is cast and integrated in a filling portion for connecting the PCa plates to each other, and the upper end bars of the main bars of the PCa plates and A plurality of joint bars extending in the upper and lower stages where the lower end bars extend to the padding part, and a plurality of lateral bars extending in the upper and lower stages arranged in the padding part so as to be orthogonal to the joint bars. In the end portions of the plurality of joint bars, expanded diameter portions are formed, and the cover concrete on the open surface of the PCa plate is subjected to stress acting on the joint bars. A cover peeling suppression reinforcing material that prevents extrusion and peeling is disposed on the outer side in the vertical direction on the opened surface side and on the inner side of the enlarged diameter portion among the upper and lower reinforcing bars of the plurality of joint bars. It is characterized by being.

  The joint structure of the PCa plate according to claim 2 is the joint structure of the PCa plate according to claim 1, wherein the fog peeling suppression reinforcing material has an open end with one side of four sides open as a lower end or an upper end. It is characterized by a horizontal U-shape.

  The joint structure of the PCa plate according to claim 3 is the joint structure of the PCa plate according to claim 2, wherein the fog peeling suppression reinforcing material has an enlarged cross section at the open end. An enlarged portion is formed.

  The construction method of a joint structure of PCa plates according to claim 4 is a construction method of a joint structure of PCa plates in which concrete is cast and integrated in a filling portion for connecting the PCa plates to each other. PCa plate having PCa plates having a plurality of joint bars in which a streak and a bottom streak extend outward and a diameter-expanded part is formed at the end part, and are arranged in parallel with a predetermined interval to be the padding part. A cover peeling suppression reinforcing material that prevents the cover concrete on the open surface of the padding portion from being pushed and peeled off by the stress acting on the joint bar after the plate juxtaposing step and the PCa plate juxtaposing step. A reinforcing material arranging step of arranging the inside of the enlarged-diameter portion on the outside in the vertical direction on the opened surface side among the upper and lower reinforcing bars of the plurality of joint bars.

  According to the first to third aspects of the present invention, the cover peeling suppression reinforcing material that prevents the cover concrete on the open surface of the PCa plate from being pushed and peeled by the stress acting on the joint bar is provided with a plurality of joints. Since the upper and lower bars of the muscle are arranged on the opened surface side in the vertical direction outside and on the inside of the enlarged diameter portion, the brittle structure in which the cover concrete is extruded in the joint structure of the PCa plate The width (dimension) of the padding portion can be shortened while suppressing the destruction mode. For this reason, when the present invention is applied to a pier structure, the upper flange width of the steel girder of the pier structure can be reduced, and the steel girder can be optimally designed according to the strength. Become. In addition, even when the present invention is applied to a bridge floor slab, it is possible to reduce the amount of concrete on-site by reducing the width of the interstitial part as much as possible, such as renewing half of each side while using (shared) the bridge. The period can be shortened.

  In particular, according to the second aspect of the present invention, since the cover peeling suppression reinforcing material has a U-shape in a horizontal view having an open end with one side of the four sides open, after the PCa plate is installed, Therefore, it is possible to easily dispose the fog peeling suppression reinforcing material at a predetermined place. For this reason, the work time of the construction work of the joint structure of PCa version can be shortened, and the installation cost can be reduced.

  In particular, according to the third aspect of the present invention, the PCa plate is the PCa floor slab because the open end of the cover peeling suppression reinforcing material is formed with an enlarged portion in which the cross section of the covering peeling suppression reinforcing material is enlarged. Even when the fixing length is not taken at the straight line up to the open end of the cover peeling prevention reinforcing material such as when the plate is thin, the necessary adhesion can be obtained and the cover concrete is extruded. It becomes possible to suppress a brittle fracture mode.

  According to the invention described in claim 4, after the PCa plate side-by-side step, the cover peeling suppression reinforcing material that prevents the cover concrete on the open surface of the PCa plate from being pushed and peeled by the stress acting on the joint reinforcement. Is disposed on the outside in the vertical direction on the opened surface side and on the inside of the enlarged diameter portion among the upper and lower reinforcing bars of a plurality of joint bars, so that the brittleness that covers concrete is extruded in the joint structure of the PCa plate The width (dimension) of the padding portion can be shortened while suppressing a typical destruction mode. For this reason, when the present invention is applied to a pier structure, the upper flange width of the steel girder of the pier structure can be reduced, and the steel girder can be optimally designed according to the strength. Become. In addition, even when the present invention is applied to a bridge floor slab, it is possible to reduce the amount of concrete on-site by reducing the width of the interstitial part as much as possible, such as renewing half of each side while using (shared) the bridge. The period can be shortened.

It is a perspective view which shows the jetty structure which has the joint structure of the PCa plate which concerns on embodiment of this invention. It is a vertical sectional view orthogonal to the steel beam which shows the joint structure of the PCa plate concerning the embodiment of the present invention. It is a vertical sectional view along the steel girder showing the joint structure of the above. It is a partial expansion perspective view which shows the joint structure same as the above in the state before placement of interstitial concrete. It is a perspective view which shows the fog peeling suppression reinforcement material which concerns on embodiment of this invention. It is a vertical sectional view orthogonal to the steel beam which shows the joint structure of the conventional PCa floor slab. It is a vertical sectional view along the steel girder showing the conventional joint structure. It is process explanatory drawing which shows the PCa plate juxtaposition process of the construction method of the joint structure of the PCa plate which concerns on embodiment of this invention. It is process explanatory drawing which shows the horizontal direction reinforcement arrangement | positioning process of the construction method of the joint structure same as the above. It is process explanatory drawing which shows the reinforcing material arrangement | positioning process of the construction method of a joint structure same as the above. It is process explanatory drawing which shows the filler filling process of the construction method of a joint structure same as the above. It is explanatory drawing explaining that the width | variety of a padding part does not shrink in the joint structure of the conventional PCa floor slab.

  Hereinafter, an embodiment for carrying out a joint structure of a PCa plate and a construction method thereof according to the present invention will be described in detail with reference to the drawings.

<PCa plate joint structure>
First, the joint structure of the PCa plate according to the embodiment of the present invention will be described with reference to FIGS. The case where the joint structure of the PCa plate according to the present invention is applied to a floor slab constituting a jetty structure installed in a harbor or the like will be described as an example.

  FIG. 1 is a perspective view showing a pier structure PS having a PCa plate joint structure according to an embodiment of the present invention. As shown in FIG. 1, a pier structure PS according to the illustrated embodiment has a steel girder G suspended between steel pipe piles P standing at predetermined intervals via a jacket, and a plurality of PCa floors on the steel girder G. It is a structure in which the plates S,..., S are placed at a predetermined interval to be a filling portion described later. The pier structure PS is installed in a harbor or the like, and is used as an artificial ground for a pier of a large passenger ship.

  FIG. 2 is a vertical cross-sectional view orthogonal to a steel girder G showing a joint structure 1 (hereinafter simply referred to as joint structure 1) of a PCa floor slab that is a joint structure of a PCa plate according to an embodiment of the present invention. These are vertical sectional views along the steel beam G showing the joint structure 1. FIG. 4 is a partially enlarged perspective view showing the joint structure 1 before the interstitial concrete C is placed.

  As shown in FIGS. 2 to 4, the joint structure 1 is a structure for connecting and integrating the PCa floor slabs S described above, and is a space (interval) formed between the PCa floor slabs S. This is a structure applied to the padding portion 2. A filler such as concrete C or mortar is placed in the padding portion 2 so that the PCa floor slabs S are integrated with each other.

  This joint structure 1 has joint bars 3 and 4 in which upper and lower bars S1 and S2 of the main bars of the PCa floor slab S extend to the padding portion 2, and bar arrangements so as to be orthogonal to these joint bars 3 and 4. A plurality of lateral stripes 5 extending over the upper and lower stages and a cover peeling suppression reinforcing material 6 are provided.

  In addition, the code | symbol SJ is a stud with a head, this stud with a head SJ is welded by steel welding to the steel girder G, and the steel girder G and the PCa floor slab S are synthesize | combined by the concrete C of the padding part 2. , Have a function to integrate.

(Joint bars)
The joint bars 3 and 4 are deformed steel bars (JISG3112) for reinforced concrete such as SD345 and SD390 in which the main bars of the PCa floor slab S are extended to the outside and project to the padding portion 2, and the illustrated form is a deformed bar with the designation D19. It is. A joint bar 3 is obtained by extending the upper bar S1 of the main bar of the PCa floor slab S, and a joint bar 4 is obtained by extending the lower bar S2 of the main bar of the PCa floor slab S. Of course, the joint bars 3 and 4 are not limited to deformed bars, and may be other steel materials.

  Further, at the end portions of these joint bars 3 and 4, there are formed enlarged diameter portions 3a and 4a in which a tubular steel material is crimped and fitted as a crimping grip around the deformed reinforcing bars to increase the diameter of the reinforcing bars. Has been. In the diameter-expanded portion according to the present invention, a nut or the like may be screwed to the threaded reinforcing bar, or the end portion of the reinforcing bar may be diameter-expanded mechanically or by applying heat. In short, the enlarged diameter portion according to the present invention is subjected to a supporting pressure when stress is applied in the direction in which the vicinity of the end of the joint reinforcement is enlarged and the joint reinforcement is pulled out from the interstitial concrete C (filler). Any structure can be used.

(Lateral stripe)
Similar to the joint bars 3 and 4, the transverse bar 5 is a deformed steel bar for reinforced concrete (JISG3112) such as SD345 and SD390, and the illustrated form is a deformed bar having a nominal name D19.

(Cover peeling prevention reinforcement)
FIG. 5 is a perspective view showing the fog peeling suppression reinforcing material 6 according to the embodiment of the present invention. The cover peeling suppression reinforcing material 6 according to the present embodiment is made of a deformed steel bar for reinforced concrete (JISG3112) having a deformed reinforcing bar such as a nominal name D16. As shown in FIG. 5, the fog peeling suppression reinforcing material 6 is a horizontal view that is an open end 6 a in which one side of the lower end of the four sides including the upper side 60 and the pair of left and right side sides 61 and 62 is opened. It is bent into the shape of

  Of course, the cover peeling suppression reinforcing material according to the present invention is not limited to a steel bar, and may be a strip-shaped steel material. The material is not limited to iron, and may be a new material such as organic fiber such as polyvinyl alcohol (PVA) fiber, polypropylene fiber, or aramid fiber, or inorganic fiber such as carbon fiber or glass fiber. In short, the delamination-suppressing reinforcing material according to the present invention only needs to have the strength and the adhesive force required to fulfill the above functions.

  As shown in FIGS. 2, 4, etc., the cover peeling suppression reinforcing material 6 according to the present embodiment is located immediately on the inside of the enlarged diameter portion 3 a on the PCa floor slab S side, above the joint reinforcement 3 that is the upper end reinforcement. It is installed so that the upper side 60 is placed. The cover peeling suppression reinforcing material 6 prevents the end portion of the joint bar 3 from rotating upward by the upper side 60 by the adhesion and fixing force of the side sides 61 and 62 to the concrete C, and prevents the padding portion 2 The cover concrete has a function of suppressing extruding and peeling.

  The reason why the upper side 60 of the cover peeling suppression reinforcing member 6 is placed above the joint bar 3 is that the PCa placed on the steel beam G of the pier structure PS such as the joint structure 1 is installed. This is because, in the joint structure of the floor slab S, the stress acting on the joint bar 3 which is the upper end bar on the open surface side has a tensile advantage. In other words, in the joint structure 1 in which the joint bar 3 has a tensile advantage, the diameter-enlarged portion 3a rises in an arc by a phenomenon close to the Dowel action, so that the concrete C cover concrete on the open surface of the padding portion 2 is obtained. However, the force acts in the direction pushed out by the joint bar 3.

  Therefore, when the present invention is applied to a floor deck of a bridge or the like, when the stress acting on the joint bar 4 which is the lower end bar is usually in a tensile advantage, the cover peeling suppression reinforcing member 6 is upside down from the illustrated form. It is necessary to install in the state of.

  In addition, the reason why the fog peeling suppression reinforcing material 6 is installed in the immediate vicinity of the inside of the enlarged diameter portion 3a is to prevent the enlarged diameter portion 3a from rising in an arc, by the principle of lever ( This is because it is more advantageous to install it near the tip of the joint bar 3. And by arrange | positioning the fog peeling suppression reinforcement material 6 inside the enlarged diameter part 3a, it is because the upper side 60 of the fog peeling suppression reinforcement material 6 is latched by the enlarged diameter part 3a.

  In short, the cover peeling suppression reinforcing material according to the present invention is arranged on the outer side of one of the joint bars 3 and 4 where the tensile force which is the open surface side acts and on the inner side of the enlarged diameter parts 3a and 4a. It only has to be done.

  In addition, in the joint structure 1 which concerns on this embodiment, since it is a pier structure PS, the plate | board thickness of PCa floor slab S will usually be 300 mm or more. For this reason, the necessary adhesion fixing force can be ensured only by the length of the pair of left and right linear sides 61 and 62 as in the case of the fog peeling suppression reinforcing material 6 according to the present embodiment. However, when the present invention is applied to a bridge slab, ordinarily, when the PCa slab S is thin, the necessary adhesion and fixing force can be obtained by providing a hairpin hook bent at 135 degrees or more at the open end 6a. It is preferable to provide appropriate means for ensuring.

  In addition, as another means for ensuring the adhesion and fixing force required when the fixing length is insufficient due to the linear length alone, an enlarged portion (in which the cross section is enlarged at the open end 6a of the fog peeling suppression reinforcing member 6) It is conceivable to form (not shown). According to the present means, the work of arranging the cover peeling suppression reinforcing material 6 is only inserted from above or below, so that the workability is extremely good as compared with the case where a hairpin hook or the like is provided.

<Operational effect of joint structure of PCa plate>
Next, the effects of the joint structure 1 described above will be described using FIGS. 6 and 7 in comparison with the joint structure of a conventional pier structure PCa floor slab. FIG. 6 is a vertical cross-sectional view orthogonal to a steel girder G showing a joint structure 1 ′ of a conventional PCa floor slab, and FIG. 7 is a vertical cross-sectional view along the steel girder G showing the joint structure 1 ′.

  The joint structure 1 ′ includes joint bars 3 ′ and 4 ′ in which the upper bar S1 ′ and the lower bar S2 ′ of the main bars of the PCa floor slab S ′ extend to the padding portion 2 ′, and the joint bars 3 ′, A plurality of lateral stripes 5 'are arranged across the upper and lower stages, which are arranged so as to be orthogonal to 4'. Further, concrete C is placed in the interstitial portion 2 'so that the PCa floor slabs S' are integrated with each other.

  Similar to the joint structure 1 described above, a tubular steel material is crimped and fitted as a crimping grip around the deformed reinforcing bars to the ends of the connecting reinforcing bars 3 'and 4', and the diameter of the reinforcing bars is increased. The expanded diameter portions 3a ′ and 4a ′ are formed.

  Here, as shown in FIG. 6, the required joint length L 'of the joint structure 1' is required to be 15 times or more the nominal diameter of the reinforcing bar as described in the background art. In the illustrated embodiment, since the joint bars 3 ′ and 4 ′ are deformed bars of D19, 15φ = 285 mm is required.

  On the other hand, as shown in FIG. 2, the required joint length L of the joint structure 1 can be 10 times or less the nominal diameter of the reinforcing bar, that is, 10φ = 190 mm. This is because, according to the joint structure 1, the cover peeling suppression reinforcing material 6 causes the enlarged diameter portion 3 a to rise in an arc by a phenomenon close to the Dowel effect, and the cover on the open upper surface of the concrete C in the filling portion 2. This is because the concrete can be prevented from being pushed out by the joint bars 3.

  That is, according to the joint structure 1 according to the present embodiment, it is possible to shorten the width (dimension) of the padding portion while suppressing a brittle fracture mode in which the cover concrete is peeled off. For this reason, the upper flange width of the steel girder G of the pier structure PS can be made smaller than the width of the conventional steel girder G ′, and the pier structure PS can be optimally designed according to the strength. It becomes.

<Construction method for PCa joint structure>
Next, the construction method of the joint structure of the PCa plate according to the embodiment of the present invention will be described with reference to FIGS. The case where the above-described joint structure 1 is constructed will be described as an example. Hereinafter, the construction method of the joint structure of the PCa plate according to the embodiment of the present invention is simply referred to as the construction method of the joint structure 1.

(1) PCa plate side-by-side process First, as shown in FIG. 8, in the construction method of the joint structure 1 according to the present embodiment, the joint bars 3 and 4 in which the enlarged diameter portions 3a and 4a are formed at the end portions described above. A PCa plate juxtaposition process is performed in which a plurality of PCa floor slabs S having a plurality of PCa plates are juxtaposed at predetermined intervals.

  Specifically, the PCa floor slab S is lifted using a lifting machine such as a crane and is placed on the steel beam G of the pier structure PS at a predetermined interval.

(2) Lateral reinforcement arrangement process Next, in the construction method of the joint structure 1 according to the present embodiment, a lateral reinforcement arrangement process is performed in which the lateral reinforcement 5 of the padding portion 2 is arranged at a predetermined position. .

  Specifically, as shown in FIG. 9, a plurality of lateral bars 5 are arranged at predetermined positions at a predetermined pitch, and are joined with binding wires or the like so as not to move when the concrete C is placed. Tie to muscles 3 and 4 and fix.

  In addition, transportation of the horizontal streak 5 is performed by fixing the necessary number together in the space above the step portion of the precast concrete of the PCa floor slab S and transporting it with the PCa floor slab S by a lifting machine in the previous process. preferable. This is because the long and heavy lateral muscles 5 that are difficult to transport by human power can be transported safely and easily, and the time required for transport can be shortened.

(3) Reinforcing Material Arrangement Step Next, in the method for constructing the joint structure 1 according to the present embodiment, the above-described cover peeling suppression reinforcing material 6 is formed on the joint reinforcement 3 that is an upper end line arranged on the opened upper surface side. A reinforcing material arranging step is arranged above and inside the enlarged diameter portion 3a.

  Specifically, as shown in FIG. 10, it is installed so that the upper side 60 is placed above the joint bar 3 which is the upper end bar, immediately inside the diameter-adjusted part 3 a on the PCa floor slab S side. It is bound and fixed to the joint bars 3 and 4 with a binding wire so that it does not move when the concrete C is placed. Further, as shown in FIG. 4 and the like, the enlarged diameter portion 3a of the PCa floor slab S on the left side of the drawing is similarly bound and fixed. At this time, it fixes so that the cover peeling suppression reinforcement material 6 may be arranged alternately so that a strong weak point may not be made.

  It is preferable that the cover peeling suppression reinforcing material 6 is also transported together with the PCa floor slab S by a hoisting machine, similarly to the lateral stripe 5.

  Note that (2) the lateral reinforcement arrangement process and (3) the reinforcing material arrangement process may be performed in parallel, or the reinforcement material arrangement process may be performed prior to the lateral reinforcement arrangement process. .

  At this time, as described above, the shape of the cover peeling suppression reinforcing material 6 is a U-shape in a horizontal view having an open end 6a in which a lower end formed by the upper side 60 and the side sides 61 and 62 is opened. For this reason, even in the interstitial part 2 with few gaps in which the joint bars 3 and 4 and the lateral bar 5 are entangled, it can be easily arranged by only being pointed in from above.

  Therefore, it is possible to reduce the installation cost by shortening the working time of the reinforcing material arranging step and the lateral reinforcing bar arranging step, and hence the working time of the construction work of the joint structure 1.

(4) Filler Filling Step Next, in the method for constructing the joint structure 1 according to the present embodiment, a filler filling step of filling the filling portion 2 with the filler is performed.

  Specifically, as shown in FIG. 11, concrete C is placed and filled in the filling portion 2 as a filler. Needless to say, the filling material to be filled in the filling portion 2 is not limited to concrete and is expensive, but it is also possible to use a mortar or other time-hardening material that hardens after a certain period of time depending on the application.

  After that, when a predetermined curing period in which the concrete C develops a predetermined strength elapses, the PCa floor slabs S and the steel girders G of the jetty structure PS and the PCa floor slab are solidified and integrated. Thereby, all the work processes of the construction method of the joint structure 1 according to the present embodiment are completed.

  According to the construction method of the joint structure 1 according to the present embodiment, as described above, in the joint structure 1 of the PCa floor slab, while suppressing the brittle fracture mode in which the cover concrete of the padding portion 2 is extruded, The width (dimension) of the stuffing part 2 can be shortened. Moreover, since the width | variety of the padding part 2 becomes narrow, not only the placement amount of concrete C can reduce and material cost can be reduced, but the installation cost by shortening working time can also be reduced.

  Heretofore, the joint structure of the PCa plate and the construction method thereof according to the embodiment of the present invention have been described in detail. However, each of the above-described or illustrated embodiments is merely a specific embodiment for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. Is.

  In particular, the case where the present invention is applied to a pier structure as a PCa plate has been described as an example, but the present invention can also be applied to a PCa floor plate of a bridge. Even in such a case, it is clear that the width (dimension) of the padding portion can be shortened while suppressing the brittle fracture mode in which the cover concrete is extruded. Therefore, when the present invention is applied to a bridge slab, it is possible to reduce the amount of concrete placed on the spot by reducing the width of the interspaced portion as much as possible, while shortening the construction period, while using (shared) the bridge. This is extremely useful when updating half by one side.

  Moreover, although the PCa floor slab was illustrated and demonstrated as a PCa plate, this invention is applicable to the joint structure of PCa plates. Even in such a case, it is clear that the width (dimension) of the padding portion can be shortened while suppressing the brittle fracture mode in which the cover concrete of the joint portion is extruded.

PS: Pier structure P: Steel pipe pile G, G ': Steel girder SJ: Stud with head (Stud gibber)
S, S ': PCa floor slab (PCa version)
S1, S1 ': upper end bars S2, S2': lower end bars 1: PCa floor slab joint structure (PCa version joint structure)
1 ': Conventional PCa floor slab joint structure 2, 2': Spacing portions 3, 3 ', 4, 4': Joint bars 3a, 3a ', 4a, 4a': Expanded diameter portions 5, 5 ': Horizontal Directional stripe 6: Cover peeling suppression reinforcing material 6a: Open end 60: Upper side 61, 62: Side C: Concrete (filler)

Claims (4)

It is a joint structure of PCa plates in which concrete is cast and integrated at a filling portion connecting the PCa plates,
A plurality of joint bars over the upper and lower stages in which the upper and lower bars of the main bars of the PCa plate extend to the padding portion;
A plurality of lateral streaks across upper and lower stages arranged to be orthogonal to the plurality of joint bars in the padding portion,
The end portions of the plurality of joint bars are formed with expanded diameter portions, respectively, and
The cover peeling suppression reinforcing material for preventing the cover concrete of the open surface of the PCa plate from being pushed and peeled by the stress acting on the joint bars is the upper strip and the lower bars of the plurality of joint bars. A joint structure for PCa plates, wherein the joint structure is disposed on the outer side in the up-down direction on the opened surface side and on the inner side of the enlarged diameter portion. 2. The PCa plate joint structure according to claim 1, wherein the cover peeling suppression reinforcing material has a U-shape in a horizontal view with an open end having one of four sides open as a lower end or an upper end. The joint structure for a PCa plate according to claim 2, wherein the open end is formed with an enlarged portion in which a cross section of the cover peeling suppression reinforcing material is enlarged. A method for constructing a joint structure of PCa plates in which concrete is cast and integrated at a filling portion for connecting the PCa plates,
PCa plates having a plurality of joint bars in which the upper and lower bars of the main bars extend outwardly and the diameter-expanded part is formed at the end are arranged with a predetermined interval as the padding part. PCa plate side-by-side installation process,
After the PCa plate side-by-side step, a cover peeling suppression reinforcing material that prevents the cover concrete on the open surface of the padding portion from being pushed and peeled by stress acting on the joint bars, the plurality of joint bars A reinforcing material disposing step of disposing the reinforcing material in a vertically outer side on the opened surface side and an inner side of the enlarged diameter portion of the upper and lower end bars of the PCa plate. Method.

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