JP2001049621A - Joint structure and joining method for precast floor plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the safety and facility of construction and to reduce the total costs by downward fitting a spiral reinforcement from above into loop reinforcements which are zigzag disposed in a manner protruding from both side end faces of respective floor plates. SOLUTION: A leading precast floor plate 1 is mounted on an upper face of a bridge girder, and a second precast floor plate 1 temporarily placed on the same with a predetermined interval from the leading one is slid, whereby opposed projective joint pieces 1a, 1a are connected together. Next, loop reinforcements 2, 2 arranged on both side end face 1b, 1b of the respective floor plates at predetermined intervals, in a manner being vertical with respect to a floor face, are alternately zigzag protruded therefrom. Then, a spiral reinforcement 4 or a connected ring reinforcement having a pitch at which the reinforcement can be fitted into gaps of the loop reinforcements 2 is downward fitted from above in a direction orthogonal to a bridge shaft. Thus, even if the number of main reinforcements is smaller than that of a conventional loop joint, the present loop joint can maintain the same strength as that of the conventional one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a joint portion of a precast floor plate used as a floor plate of a road bridge and a method of joining the same. More specifically, the present invention relates to a method of mounting a precast floor plate manufactured in a factory on a bridge girder. The present invention relates to a joint portion structure and a joint method for erection.

[0002]

2. Description of the Related Art In recent years, in the construction of road bridges, prestresses manufactured in factories have been replaced with conventional cast-in-place floor boards in order to save labor and reduce costs and improve quality and durability of on-site work. The use of precast floorboards with the introduction of is increasing.

[0003] As one of the examples, as shown in FIG.
1b and 21b, the horizontal U-shaped loop reinforcing bars 22 and 22 perpendicular to the floor surface are alternately overlapped with each other, and the inside of each loop reinforcing bar 22 and 22 is formed along the direction perpendicular to the bridge axis. The main reinforcing bar 23 composed of a plurality of straight bars is inserted into each of the intermediate portion and the lower portion, and concrete is cast and joined.

[0004]

However, in order to insert the main reinforcing bar 23 into each of the loop reinforcing bars 22, 22, a special projecting scaffold H is provided on the side surface of the bridge girder B as shown in FIG. , Long main reinforcement 2 with its overhanging scaffold H
3 was inserted into the loop rebars 22, 22, and the insertion work took a long time, and the main rebar was heavy, resulting in heavy labor. Further, since the work is performed on the overhanging scaffold H, not only a special worker is required, but also the scaffold is unstable and involves danger, so that the work must be performed with great care. Further, a great deal of labor and cost was required to make the overhanging scaffold H.

[0005] Each of the main reinforcing bars 23 inserted into each of the loop reinforcing bars 22 must be bound with each of the loop reinforcing bars 22, and in particular, the reinforcing bars 2 inserted into the middle portion and the upper portion.
In the bundling work of No. 3, the bundling had to be performed while the reinforcing bar was lifted, which was troublesome, and the bundling work was difficult in a narrow space.

SUMMARY OF THE INVENTION The present invention has been developed with the object of solving the above problems, and can maintain the same level of strength even if the number of main bars is smaller than that of a conventional loop joint. To provide a joint structure of a precast floor panel and a joint method thereof, which enable construction on a bridge surface in all work, improve work safety, and facilitate construction and reduce total cost. It is intended for.

[0007]

According to the present invention, as a means for solving the above-mentioned problems and achieving the object, the present invention relates to a method in which the precast floorboards are provided at predetermined intervals on opposite side end faces thereof. The loop-shaped reinforcing bars are arranged alternately in a staggered manner, and a spiral reinforcing bar or a connecting ring reinforcing bar is arranged between the loop-shaped reinforcing bars along the direction perpendicular to the bridge axis. The joint structure of precast floorboards was developed and adopted.

Further, in the present invention, straight lines are alternately provided on the opposite side end surfaces of the precast floor plate at predetermined intervals at upper and lower portions which are horizontal to the floor surface, and are arranged in a staggered manner. We developed and adopted a joint structure for precast floor plates, characterized by arranging helical reinforcing bars or connecting ring reinforcing bars along the direction perpendicular to the bridge axis between the straight bars.

Further, in the present invention, in the joint structure of the precast floor plate configured as described above, the precast floor plate is provided with projecting joint pieces having different lengths at both lower end surfaces, and the left and right are formed in an asymmetric shape. The joint structure of the precast floor slab and the precast floor slab are provided with the same length of protruding joint pieces on both lower end surfaces, and the joint structure of the precast floor slab which is formed symmetrically on the left and right is developed. , Adopted.

As a means for solving the above-mentioned problems and achieving the object, according to the present invention, a succeeding precast floor plate is provided on one side surface of a preceding precast floor plate placed on the upper surface of a bridge girder with an interval. Side-by-side and temporarily placed, slide the precast floorboard of this succeeding from the front to the preceding precast floorboard side to join the opposing projecting joint pieces, and perpendicular to the floor surface at predetermined intervals provided on the side end surface The loop-shaped rebars are alternately protruded and arranged in a staggered manner, and a spiral rebar having a pitch fitted between the loop-shaped rebars or a connection ring rebar connected so that each ring is fitted in a direction perpendicular to the bridge axis. We have developed and adopted a joint method for joints of precast floorboards, which is characterized in that the joints are constructed by dropping and fitting from the top.

Further, as a means for solving the above-mentioned problems and achieving the object, according to the present invention, one long protruding joint piece of a preceding precast floor plate placed on the upper surface of a bridge girder is provided.
Lower from the top so that the other short projecting joint piece of the succeeding precast floor plate is joined, and alternately project straight lines to the upper and lower parts horizontal to the floor at predetermined intervals provided on the opposing side end faces. The spiral joints are arranged in a zigzag pattern, and a spiral reinforcing bar having a pitch fitted between the straight bars or a connecting ring reinforcing bar connected so as to fit each ring is dropped from above in the direction perpendicular to the bridge axis, and the joint is fitted. We developed and adopted a joint method for joints of precast floorboards, which is characterized by construction.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a joint structure of a precast floor plate according to the present invention; FIG. FIG. FIGS. 2 to 4 show a first embodiment of the present invention. As shown in FIG. 1, the precast floor plate 1 has a rectangular shape that is long in a direction perpendicular to the bridge axis and short in the direction of the bridge axis. This is a precast reinforced concrete slab having stepped portions formed on both side surfaces and provided with projecting joint pieces 1a and 1a on the lower end surface, and is manufactured at a factory and transported to the site.

The precast floor plates 1, 1 are arranged at predetermined intervals along opposing side end surfaces 1b, 1b, and have horizontal U-shaped loop reinforcing bars 2, 2,... Made of a steel bar perpendicular to the floor surface.
Are staggered and project alternately toward the opposing surface. The main reinforcing bars 3, 3 are previously bound to the loop reinforcing bars 2, 2, ... along the right angle of the bridge axis above and below the protruding bases of the loop reinforcing bars 2, 2, ..., respectively. It is not necessary to tie them after the installation of 1,1.

Reference numeral 4 denotes a spiral rebar formed by spirally winding a steel bar at a constant pitch P. The spiral pitch P is formed to a pitch P fitted between the above-described loop rebars 2, 2,.... The spiral reinforcing bar 4 is fitted between the loop reinforcing bars 2, 2 and so on in a direction perpendicular to the bridge axis.

The joint structure of the precast floor plate according to the present invention thus constructed retains the same strength as the conventional one by merely arranging one spiral reinforcing bar 4 in the loop reinforcing bar 2 and has a very assembled structure. This simplifies the operation and does not require the binding of the main reinforcing bars and the loop reinforcing bars as in the related art, and only the spiral reinforcing bars 4 need to be bound.

FIGS. 5 to 7 show a second embodiment of the present invention, which is different from the first embodiment in that a connecting ring reinforcing bar 5 replaces the spiral reinforcing bar 4 fitted in the direction perpendicular to the bridge shaft. Is used. The connecting ring reinforcing bar 5 is attached to a single upper reinforcing bar 5a made of a steel bar extending in a direction perpendicular to the bridge axis at predetermined intervals, that is, at intervals between the loop reinforcing bars 2, 2,. The ring 5b, 5b,... Is inserted, and the connection between the upper inner peripheral portion of each ring 5b, 5b,. Since the precast floor plate 1 and the loop reinforcing bar 2 are the same as those in the first embodiment, the same reference numerals are given and the description is omitted.

In the second embodiment, as in the first embodiment, the same strength as in the prior art is maintained by merely arranging the connecting ring reinforcing bar 5 in the loop reinforcing bar 2, and the assembling structure is extremely high. This simplifies the structure of the joint portion, and also eliminates the need to bind the main reinforcing bars and the loop reinforcing bars as in the conventional case, and suffices to bind only the connecting ring reinforcing bars 5.

FIGS. 8 to 10 show a third embodiment of the present invention. The difference from the first and second embodiments is that the side surface shapes of the projecting joint pieces 1a and 1a 'on the lower end side of the precast floor plate 1 are different. Is an asymmetric shape, and two straight reinforcing bars 6, 6 are used in place of the loop reinforcing bar 2 protruding from the side end surface.

That is, the projecting joint pieces of the precast floorboard 1 have an asymmetric shape in which one projecting joint piece 1a is lengthened and the other projecting joint piece 1a 'is shortened. On the upper and lower sides of the side end surfaces 1b, 1b, two straight reinforcing bars 6, 6,... Made of steel bars are arranged alternately in a staggered manner at predetermined intervals with respect to the floor surface. Is a point. This straight bar 6, 6 ...
... The reinforcing bars fitted therebetween are the same as the spiral reinforcing bars 4 of the first embodiment shown in FIGS. 8 and 9 or the connecting ring reinforcing bars 5 of the second embodiment shown in FIG. The description is omitted.

In the third embodiment, since the straight reinforcing bars are not used as in the first and second embodiments, the form structure of the precast floor plate does not become complicated. And assembly can be simplified.

FIGS. 11 to 12 show a fourth embodiment of the present invention. The difference from the third embodiment is that the shapes of the protruding joint pieces 1a, 1a of the precast floorboards 1, 1 are symmetric from asymmetric shapes. This is the point that has been replaced by the shape. That is, projecting joint pieces 1 of the same length
a and 1a are formed. The other points are the same as in the third embodiment, and the same reference numerals are given and the description is omitted.

Next, a method for installing a joint of a precast floor plate according to an embodiment of the present invention will be described. First, the construction method of the precast floor plate 1 having the loop reinforcing bars 2 and 2 according to the first and second embodiments will be described with reference to FIGS. 13A to 13E and FIGS.
4E will be described.

The succeeding precast floor plate 1 is suspended by a crane on one side surface of the preceding precast floor plate 1 installed on the upper surface of the bridge girder B and lowered (FIGS. 13A and 14A).
Since the loop reinforcing bars 2, 2 protrude from the projecting joint pieces 1 a, 1 a at the lower end surfaces on both sides of the precast floor plates 1, they are temporarily placed with a small interval W (FIGS. 13B and 14).
B).

The temporarily placed precast floor plate 1 is slid from the near side to the preceding precast floor plate 1 side (in the direction of the arrow) to join the protruding joint pieces 1a, 1a to each other (FIGS. 13C and 14C). At this time, the rectilinear bars 3 previously bound to the loop reinforcing bars 2, 2 are arranged outside the curvature of the loop reinforcing bars 2.

When the projecting joint pieces 1a, 1a are joined, the loop reinforcing bars 2, 2 projecting from the side end faces 1b, 1b of the opposing precast floorboards 1, 1 are arranged in a staggered manner. Then, the spiral reinforcing bar 4 or the ring reinforcing bar 5 is brought upward in the direction perpendicular to the bridge axis (FIGS. 13D and 14D). It is dropped from that position and fitted between the loop reinforcing bars 2 and 2 (FIGS. 13E and 14E).

According to this joint construction method, the spiral reinforcing bar 4 and the connecting ring reinforcing bar 5 can be inserted into the loop reinforcing bars 2 and 2 from the precast floor plate without providing an overhanging scaffold as in the prior art. In addition, the assembling work can be performed very easily and safely, and the construction becomes easy.

Further, straight bars 6, 6 are provided on the upper and lower portions of the opposing side end surfaces of the precast floorboards of the third and fourth embodiments,
15A to 15D and FIGS. 16A to 16D illustrate a method of applying the precast floor panel 1 in which the projecting joint pieces 1a and 1a 'on both side lower end faces are asymmetrical. 17A to 17E and FIGS. 18A to 18E will be described.

FIGS. 15A to 15D and FIGS. 16A to 1
In the case where the projecting joint pieces 1a and 1a 'shown in FIG. 6D are asymmetrical precast floor plates 1, the main reinforcing bars 3 along the direction perpendicular to the bridge axis are previously attached to the vertical reinforcing bars 6 and 6 before the precast floor plates 1 are erected. A long projecting joint piece 1a on one side of the preceding precast floor panel 1 laid on the upper surface of the bridge girder B beforehand
Is lowered from above so as to join the short projecting joint pieces 1a 'on the other side of the subsequent precast floor plate 1, and the projecting joining pieces 1a, 1a' are joined together (FIGS. 15A and 15B).
16A and 16B). Projecting joint pieces 1a, 1a '
Are joined, the upper and lower two straight reinforcing bars 6, 6 projecting from the side end surfaces 1b, 1b of the opposing precast floorboards 1, 1 are arranged in a staggered staggered manner. Then, the spiral reinforcing bar 4 or the ring reinforcing bar 5 is brought upward in the direction perpendicular to the bridge axis (FIGS. 15C and 16C). Drop it from that position and fit it between the loop reinforcing bars 2 and 2 (FIG. 15).
D and FIG. 16D).

In the case of the first and second embodiments, the connection was slid in the horizontal direction after the temporary placement before the setting once, but according to the method of installing the joint, such a process is performed. It is not necessary to do so, and the work can be performed extremely easily and the construction becomes easy.

FIGS. 17A to 17E and FIG. 18A
18E, the projecting joint pieces 1a, 1a are symmetrically shaped precast floorboards, as in the first and second embodiments.
The following precast floor plate 1 is suspended by a crane on one side of the preceding precast floor plate 1 installed on the upper surface of the bridge girder B, and the loop reinforcing bars 2 and 2 protrude from both lower end surfaces of the precast floor plates 1 and 1. Are temporarily placed with a slight interval W (FIGS. 17B and 18B).

The temporarily placed precast floor plate 1 is slid from the near side to the preceding precast floor plate 1 to join the projecting joint pieces 1a, 1a to each other (FIGS. 17C and 18C). Then, the straight reinforcing bars 6, 6 protruding from the opposing surfaces of the opposing precast floorboards 1, 1 are in a staggered arrangement.

Then, the spiral reinforcing bar 4 as shown in FIG. 4 or the connecting ring reinforcing bar 5 as shown in FIG. 7 is brought upward in the direction perpendicular to the bridge axis (17D and 18D). It is dropped from that position and fitted between the loop streaks 2, 2, ... (17E and 18E).

Next, in order to demonstrate the effects of the load bearing capacity and the spiral reinforcing bar on the behavior of the actual bridge between the first and third embodiments of the present invention and the conventional loop joint, a test piece having an RC structure was used. The safety of the joints against static load and the effect of the spiral rebar were confirmed by a bending tester, and the fatigue resistance was checked by a beam shear tester.

The specimen used for the static test has a design standard strength of 5
It is 00 kgf / cm ² (50 N / mm ² ), and the filling portion is made of expanded concrete (f'ck = 500 kgf / cm ² ) for the purpose of shrinkage compensation after performing a seaming process by washing out. is there.

The loading method in the static test is as shown in FIG. 21, and the two-point concentrated line loading is a simple version. The applied load was a design load (PD = 5.5 tf) at which the bending moment in the bridge axis direction could be reproduced, and the load was applied until failure. FIGS. 21A and 21B show a case where the loading surface is changed assuming a behavior in an actual bridge, and FIG. 21C shows a case where the span is shortened to confirm the shear strength.

The types of the joints are the tests in the first and third embodiments with and without the spiral muscle and the loop joints of the conventional example. Table 1 shows combinations of types of joints and loading methods in each test.

[Table 1] * 1: Due to preloading, the test results up to around 8tf have a different tendency from other types.

Ultimate strength The breaking loads of the test specimens in each loading method are shown in Tables 2, 3 and 4.
As shown in FIG.

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

[0040] The final state was that the upper edge of the concrete at the center of the span was crushed in all the specimens in case-1 and case-2. Similarly, in case-3, bending failure occurred, and concrete upper edge collapse occurred. In the loading methods case-1 and case-2, no significant difference was observed in all the test pieces, and the ultimate proof stress was equivalent. Using a loop joint (conventional example, first embodiment)
Has 1 or 2 cracks at the center of the span, and was broken in a state in which the center portion and both ends of the test piece were displaced. On the other hand, in the third embodiment, the number of cracks at the center of the span was two or three, and a beam-like fracture was formed. Cracks occurred inside the joints in all types of the specimens without spiral streaks. In the type with spiral streaks, cracks occur at the corners of the joint,
No crack occurred at the center of the joint.

FIG. 2 shows the state of occurrence of cracks in the test specimen in each loading method.
2 to 24 and Tables 5 to 7.

[Table 5]

Design Load Loading (PD) Initial cracking was 4.5-5.5 in all specimens.
It occurred at the joint joint at tf. 1.5PD loading ・ Cracks occurred at the center of the span in all the test specimens. Cracks generated at joint joints of the conventional loop joint and the type of the first embodiment evolved with loading, cracks at the fulcrum-side joint extended to near the lower main reinforcement, and the joint at the loading point-side extended to near the center of the plate thickness. . In the type of the third embodiment, the crack at the loading point side seam similarly developed,
There was no progress on the fulcrum joint. 2.0PD loading ・ The seam crack on the loading point side and the center crack between the struts grew to about 200 mm from the lower edge. 3.0PD loading ・ The seam crack on the loading point side has advanced to the upper main reinforcing bar position toward the loading point.・ After the main bar yielded, horizontal cracks developed along the upper main bar, leading to concrete upper edge crushing.

[0043]

[Table 6]

Design load loading (PD) Initial cracks occurred at the loading point side joint and the center of the span at 3 to 5 tf in all the test specimens, and developed near the position of the lower main reinforcing bar. 1.5PD loading-Cracks occurred at the fulcrum side joints, and the cracks at the fulcrum side joints and at the center between the supports extended to near the center of the plate thickness. 2.0PD loading ・ In the third embodiment, a second crack occurred at the center of the span, and the existing crack extended to about 200 mm from the lower edge. 3.0PD loading ・ Similar to case-1, cracks were directed in the direction of the loading point in the vicinity of the upper main reinforcing bar.

[0045]

[Table 7]

Design Load Loading (PD) In the conventional loop joint type, initial cracks occurred at the loading point side joint. 1.5PD loading ・ Bending cracks occurred in both types (conventional loop joint, Embodiment 3) in the center of the span. (Conventional loop joint type: 13tf, Embodiment 3 type: 11tf)-In the C type, initial cracks occurred at the loading point side joint at 13tf. 2.0PD loading ・ In the conventional loop joint A type, cracks occurred in the joint. (21tf) ・ The crack at the loading point side seam has spread to near the center of the plate thickness. 3.0PD loading ・ The crack at the loading point side seam was directed toward the loading point, and the main bar yielded, the crack propagated, and the upper edge of the concrete collapsed.

[0047]

As described above, according to the joint structure of the precast floor plate of the present invention, although the number of the main reinforcement is smaller than that of the conventional loop joint, the concrete by the spiral reinforcement or the connection ring reinforcement is used. Due to the restraining force described above, the shear load-carrying capacity of the joint is improved, and the same strength as that of the conventional joint can be obtained. Since the spiral reinforcing bar or the connecting ring reinforcing bar is used as the main reinforcing bar, the assembling becomes easier, and the material cost can be reduced because the number of the main reinforcing bars is small.

Further, according to the joint method of the fifth aspect, the overhanging scaffold which has been required in the past becomes unnecessary, and all work can be performed on the floor plate of the bridge girder during construction, so that it is safe. And since the main reinforcing bar is a spiral reinforcing bar or a connecting ring reinforcing bar, it can be easily fitted between the loop reinforcing bar or the straight bar, so that the assembling work becomes easy, and the inserting work of the reinforcing bar which requires physical strength, which was conventionally performed, is omitted. The efficiency is improved.

According to the joint method of the sixth aspect, in addition to the above-mentioned effects, in addition to one of the long projecting joint pieces of the preceding precast floor board, the other short projecting joint piece of the succeeding precast floor board is joined. In this way, the joining operation is completed only by descending from the top to the bottom, and the operation step of joining by sliding in the lateral direction such as a loop reinforcing bar can be omitted. Further, since the reinforcing bars projecting from the opposite side end surfaces of the precast floor plate are straight reinforcing bars, the formwork is not complicated, and the working of the reinforcing bars can be simplified.

[Brief description of the drawings]

FIG. 1 is a simplified perspective view showing a state of being installed on a bridge girder.

FIG. 2 is an enlarged sectional view of a main part of the first embodiment.

FIG. 3 is a partially omitted plan view of the first embodiment.

FIG. 4 is a partially omitted front view of a spiral muscle.

FIG. 5 is an enlarged side view of a main part of the second embodiment.

FIG. 6 is a partially omitted plan view of the second embodiment.

FIG. 7 is a perspective view of a ring reinforcing bar.

FIG. 8 is an enlarged side view of a main part of the third embodiment.

FIG. 9 is a partially omitted plan view of the third embodiment.

FIG. 10 is an enlarged side view of a main part showing a modification of the third embodiment.

FIG. 11 is an enlarged side view of a main part of a fourth embodiment.

FIG. 12 is an enlarged side view of a main part showing a modification of the fourth embodiment.

FIG. 13 is a simplified side view showing the joint method of the first embodiment.

FIG. 14 is a simplified side view showing a joint method according to a second embodiment.

FIG. 15 is a simplified side view showing a joint method according to a third embodiment.

FIG. 16 is a simplified side view showing a joint method according to a modification of the third embodiment.

FIG. 17 is a simplified side view showing a joint method according to a fourth embodiment.

FIG. 18 is a simplified side view showing a joint method according to a modification of the fourth embodiment.

FIG. 19 is an enlarged side view of a conventional joint structure.

FIG. 20 is a perspective view of a hanging scaffold used when a conventional main bar is inserted.

FIG. 21 is a drawing showing a loading method in a static test.

FIG. 22 is a diagram showing a state of occurrence of cracks in case-1.

FIG. 23 is a diagram showing a state of occurrence of cracks in case-2.

FIG. 24 is a diagram showing a state of occurrence of cracks in case-3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Precast floor board 1a Projection joint piece 1b Side end surface 2 Loop reinforcing bar 4 Spiral reinforcing bar 5 Connecting ring reinforcing bar 6 Straight reinforcing bar

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomihiko Oishi 3-3-22 Nakanoshima, Kita-ku, Osaka City Inside Kansai Electric Power Co., Inc. (72) Inventor Hideo Takenaka 3-2-222 Nakanoshima, Kita-ku, Osaka Kansai Inside Power Corporation (72) Inventor Eiji Nakamaru 3-3-22 Nakanoshima, Kita-ku, Osaka-shi Inside Kansai Electric Power Corporation (72) Inventor Shigeyuki Matsui 4- 6-4 Yamada Nishi, Suita-shi, Osaka (72 ) Inventor Shigeru Anfuku 5-14-10 Nishitenma, Kita-ku, Osaka City Kinki Concrete Industry Co., Ltd. (72) Inventor Hiroki Hasegawa 5-14-10 Nishitenma, Kita-ku Osaka City Kinki Concrete Industry Co., Ltd. F Terms (reference) 2D059 AA14 CC03 GG55 2E125 AA57 AA68 AE02 AG07 AG29 AG34 AG38 AG60 BA46 BD01 BE08 BF01 CA82 EA33

Claims (6)

[Claims] 1. A loop-shaped reinforcing bar perpendicular to a floor surface is alternately arranged at predetermined intervals on opposite side end surfaces of a precast floor plate in a staggered manner. A joint structure for a precast floor plate, wherein a spiral reinforcing bar or a connecting ring reinforcing bar is arranged along a direction perpendicular to a bridge axis. 2. A pair of straight streaks are alternately provided at upper and lower portions horizontal to the floor at predetermined intervals on opposite side end surfaces of the precast floor plate, and are staggered. A joint structure for a precast floor plate, wherein a spiral reinforcing bar or a connecting ring reinforcing bar is arranged along a direction perpendicular to a bridge axis. 3. The joint structure for a precast floor plate according to claim 2, wherein the precast floor plate is provided with projecting joint pieces having different lengths at lower end surfaces on both sides, and the left and right are formed in an asymmetric shape. 4. The joint structure for a precast floor plate according to claim 2, wherein the precast floor plate has projecting joint pieces of the same length on both lower end surfaces, and has a symmetrical shape on the left and right sides. 5. A precast floor plate of a succeeding precast slab laid on an upper surface of a bridge girder, and a subsequent precast slab is arranged side by side with an interval, and the precast floor slab of the succeeding precast slab is positioned on the side of the preceding precast slab. Slide to join the opposing projecting joint pieces, arrange the loop-shaped reinforcing bars perpendicular to the floor surface alternately at predetermined intervals provided on the side end faces, and arrange them in a staggered manner. A joint of a precast floor slab, wherein a joint portion is constructed by dropping a spiral reinforcing bar having a pitch fitted therein or a connecting ring reinforcing bar connected so as to fit each ring from above in a direction perpendicular to a bridge shaft and fitting the joint. Section joint method. 6. A lower precast floor slab, which is placed on the upper surface of a bridge girder, is lowered from above so that the other short protruding junction of the subsequent precast floor slab is joined to one of the long protruding junctions of the preceding precast slab. At regular intervals provided on the end surface, straight bars are alternately projected and arranged in a staggered manner on the upper and lower portions horizontal to the floor surface, and spiral reinforcing bars or rings having a pitch fitted between the straight bars are fitted. A joint method for a joint part of a precast floor plate, wherein a joint part is constructed by dropping and fitting a connecting ring reinforcing bar which is connected so as to be entirely perpendicular to a bridge axis.