JPH09100512A - Joint structure of precast concrete floor slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to facilitate execution of work without producing shortening in the direction of a girder and construct partially or all over the whole length and shorten a construction period of a floor slab and replaced partially when it is damaged. SOLUTION: A continuous offset area 4 in a definite cross section and a notched part 5 to be placed on a main girder are provided on the end face of a PCa floor slab 1. The offset area 4 forms an arc-shaped recessed part 4a in the central part, thereby providing a clearance between adjacent panels. A spiral reinforcing bar is inserted into this clearance where expandable mortar is placed, thereby forming a shearing key. A loop joint bar 5b, which uses distribution reinforcement on the upper stage and the lower stage of the PCa floor slab 1, is projectingly provided on the notched part 5. The loop joint bars, which are placed one upon the other in the vertical direction, are filled up with the expandable mortar and effectively joined, thereby preventing the panels from being mutually separated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure for precast concrete floor slabs laid on girders such as bridges.

[0002]

2. Description of the Related Art In the case where a precast concrete floor slab (hereinafter referred to as PCa floor slab) having a predetermined shape is spanned in a direction orthogonal to a girder, and panels of adjacent PCa floor slabs are connected to each other to form a series of floor slabs. In order to prevent individual PCa floor slabs from exhibiting independent behavior, it is necessary to have a structure as a plate that is continuous in the girder direction. In particular, in the case of a road bridge in which a one-way isotropic infinite simple plate is modeled to design the structure of the floor slab on the premise of an RC floor slab that is cast in situ, this girder joint structure is important.

For this reason, the conventional PCa floor slab joint structure employs a so-called vertical fastening method in which a PC steel material is inserted in the girder direction and stress is introduced by post tension to integrate the floor slab. Came. In the case of this construction method, a plurality of PCa floor slabs were placed on the girder, the positions of the PCa floor slabs were adjusted, and then a PC steel material was inserted, and sheathing of the packing portion and mortar filling of the packing portion were carried out. Later, tension and grout injection were performed to introduce prestress, aiming at perfect continuity between the plates.

[0004]

However, in the case of the joint structure by the vertical tightening method, since the floor slab is shortened in the girder direction, additional stress due to creep and drying shrinkage must be taken into consideration when designing. There is a drawback that the design work becomes complicated. Further, since the contact friction between the floor slab and the girder becomes large, it is necessary to devise a method for supporting the floor slab to shorten the elasticity.

Further, since strict quality control is required in the tension work, a sophisticated and complicated construction technique is required, and the construction sequence cannot be changed even in a series of works when introducing prestress. There is a drawback that the construction period is prolonged due to various reasons such as the difficulty of dividing construction because the construction of the floor slab is limited to one-sided construction.

Further, since it is necessary to provide a jack space for tension in the floor slab portion, it is impossible to perform vertical fastening over the entire length of the floor slab. Further, when the integrated floor slab is partially damaged, it is difficult to replace the part.

The present invention solves the above-mentioned problems, does not cause girder shortening, is easy to construct, enables division construction and full length construction, shortens the construction period of floor slab construction, and enables partial replacement when damaged. It is intended to provide a joint structure for a PCa floor slab.

[0008]

In order to solve the above-mentioned problems, the joint structure of the PCa floor slab of the present invention forms a stepped portion on the end surface of the PCa floor slab arranged on the girder and a notch portion at a part thereof. A shearing force transmitting member is installed in the gap between the facing step portions, and the loop joint reinforcements connecting the upper and lower distribution reinforcing bars to form a loop-like tip project from the opposite side surfaces of the notch. However, the stepped portion and the notched portion are filled with expansive mortar to integrally connect the adjacent floor slabs.

The shearing force transmitting member may be a slip-preventing member that projects from the side surfaces of the facing step portions, or a spiral reinforcing bar may be placed in a recessed portion that faces the stepping portion and filled with expansive mortar. It may be a shear key to be formed. or,
The tip of the upper part reinforcing bar protruding from one step is formed in a loop and bent downward, and the end of the lower part reinforcing bar protruding from the other step facing the other is formed in a loop and formed upward. The structure may be such that the inflatable mortar is filled with the bent loop reinforcing bars in a state of being superposed.

At the notch at the end of the PCa floor slab, the loop-joint bars projecting oppositely overlap each other in the vertical direction, and by filling the expansive mortar, both reinforcing bars are effectively joined. This prevents the PCa floor slabs from separating from each other. The notch is mainly provided just above the girder. The floor slabs are connected to each other while adjusting the height by filling expansive mortar in the stepped portions formed on the end faces of the slabs other than the cutout portions. Further, the shearing force generated in the PCa floor slab is transmitted to the adjacent floor slab by the shearing force transmitting member built in the step portion.

As the slip prevention material, a stud with a head used in a steel / concrete composite girder or a streak protruding from the side surface of the step portion is used. Further, when the tip loops of the distribution reinforcing bars are bent and overlapped as the shearing force transmitting member, the shearing transmission is achieved by the abdominal pressure resistance of the mortar surrounded by the two loops.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Fig. 1 shows P mounted on the girder
FIG. 2 is a perspective view of the Ca floor slab, FIG. 2 is a sectional view showing a II-II section of FIG. 1, and FIG. 3 is an enlarged sectional view showing a III-III section of FIG. The PCa floor slab 1 is a panel of a predetermined shape that is stretched over the main girder 2, and the panels are integrally connected in the girder direction by the joint portion 3 to function as a continuous floor slab.

In order to form the joint portion 3, a step portion 4 having a continuous constant cross section and a notch portion 5 arranged on the main girder 2 are provided on the end surface of the PCa floor slab 1. The step portion 4 has an arc-shaped recess 4a formed at the center of the end surface of the PCa floor slab 1, and a gap is provided between adjacent panels. The main girder width of the panel is usually 150
The distance between the stepped portions 4 and 4 is about 10 cm at the maximum, and the gap between the notched portions 5 and 3 is 3 cm.
It should be about 0 to 40 cm.

The notch portion 5 has upper and lower force distribution muscles 1a and 1b projecting from the side surface 5a of the PCa floor slab 1. The tips of the force distribution muscles 1a and 1b are connected to form a loop joint muscle 5b. Further, the notch portion 5 is provided with a bottom portion 5c, but when the PCa floor slabs 1 are placed adjacently, a gap of about 1 to 2 cm is generated between the bottom portions 5c, so the sealing material 6 is filled in this portion. . By inserting and tightly inserting the through streak 5d into the loops of the loop joint muscles 5b, 5b that overlap in the vertical direction and filling the notch 5 with expansive mortar, the loop joint muscles 5b are effectively joined to each other, so that the panels are connected and Are prevented from separating.

As shown in FIG. 3, a half steel pipe 4b is embedded in the peripheral surface of the concave portion 4a of the step portion 4 to reinforce the end portion, and the lower end portion of the slit-like gap is closed by a sealing material 6. Spiral rebar 4c is arranged between the facing concave portions 4a, 4a,
Fill with expansive mortar 7 to form a shear key.

When the step portion 4 and the notch portion 5 are connected in this manner, the shearing force generated in the PCa floor slab 1 is sequentially transmitted mainly through the shear key, and the floor slab serves as a so-called sheared connection slab. Can be integrated. Further, since the site forming portion is provided between the panels, it is possible to absorb the manufacturing error of the PCa floor slab 1 and the unevenness during the panel installation.

Although the joint structure of the PCa floor slab described above is a structure in which a shear key is formed in the step portion to transmit the shearing force, the shearing force transmitting member may be a headed stud. The embodiment will be described based on FIGS. 4 and 5. FIG. 4 is a cross-sectional view of a joint portion in which a stud with a head is provided to project, and FIG. 5 is a front view of a steel plate with a stud. The step portion 14 of the joint portion 13 has the steel plate 8 with studs embedded in the end surface of the PCa floor slab 1, and the lower end portion is closed by the sealing material 6. Headed studs 8b are provided in a zigzag manner on one surface of the steel plate 8a, and anchor streaks 8c are fixed to the other surface. If the protruding length of the headed stud 8b is 5 cm, the panel interval is about 6 cm. Reinforcing bars 9 are arranged in the gaps where the studs project from the side surfaces of both step portions, and the expansive mortar 7 is filled with them.

Further, instead of the headed stud, a structure in which a differential streak protruding from the side surface of the step portion is used as a shift preventing material may be used.
An embodiment thereof is shown in FIGS. 6 and 7. This joint part 113
Even at the step portion 114 of the
The steel plate 108 is provided with holes 108a in a staggered arrangement, and the upper and lower force distribution muscles 1a and 1b of the PCa floor slab 1 are alternately projected from the holes 108a.

Further, a joint structure using a loop bar of a distribution reinforcing bar as a shear force transmitting member is also conceivable. The embodiment will be described based on FIGS. 8 and 9. FIG. 8 is a cross-sectional view of a joint portion in which a loop line is obliquely provided, and FIG. 9 is a cross-sectional view of a joint portion in which the loop line is bent in the vertical direction.

In the joint portion 23 of FIG. 8, a trapezoidal concave portion 24a is formed in the step portion 24, and the force distribution muscle 2 above the side surface is formed.
Two lathes 1a obliquely downwardly and two lower-level force distribution muscles 21b obliquely upwardly project in a zigzag manner. These muscles 21a, 21
b forms a loop muscle 20 having its ends connected to each other, and a pair of loop muscles 20 and 20 bent up and down overlap each other. In the case of this joint structure, shear transmission is achieved by the abdominal pressure resistance of the mortar surrounded by the two loops, but some bending resistance can also be exhibited.

Further, in the joint portion 33 shown in FIG. 9, the loop ribs 30 are bent in the vertical direction so that the loop ribs 30, 30 facing each other are formed.
The expansive mortars 7 are filled with them in close proximity. With this joint structure, only shear transmission is expected mainly due to the abdominal pressure resistance of the mortar, but there is an advantage that the flexibility of construction can be taken because the loop muscles do not intersect.

As described above, in the case of the floor slab structure in which the shearing force transmitting member is provided in the step portion and the expansive mortar is filled and the panels are integrated as the shear connecting plate, the vertical tightening method is not used, and therefore a part thereof is not used. Even if the PCa floor slab is damaged, it can be easily repaired by replacing the part.

[0023]

As described above, the PCa according to the present invention is used.
In the joint structure of the floor slab, since the step portion where the shear force transmitting member is installed and the notch portion where the loop joint bar is projecting are filled with expansive mortar and connected, vertical tightening with PC steel is not necessary.
For this reason, the girder direction is not shortened and the tension work is eliminated, so that the construction becomes easy. In addition, floor slabs can be installed separately,
The construction period can be shortened. Further, since a jack space for tension is unnecessary, it is possible to lay a PCa floor slab of the same structure over the entire length. Further, it becomes possible to replace a part when it is damaged.

In the case of a joint structure in which the shearing force transmitting member is used as the slip prevention member, the stop member can be arranged with high accuracy.
A reliable joint proof strength can be expected. Further, in the joint provided with the shear key, there is no member protruding from the end face when the PCa floor slab is installed, so that the flexibility of construction is great. Further, in the joint for superposing shear transmission by stacking bent loop reinforcing bars, a special joint member is not required, so that a low-cost joint structure can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a PCa floor slab placed on a girder.

FIG. 2 is a sectional view showing a II-II section in FIG. 1;

FIG. 3 is an enlarged sectional view showing a section taken along line III-III of FIG. 1;

FIG. 4 is a cross-sectional view of a joint portion in which a headed stud is provided to project.

FIG. 5 is a front view of a steel plate with studs.

FIG. 6 is a cross-sectional view of a joint portion provided with a protruding rib.

FIG. 7 is a front view of a steel plate.

FIG. 8 is a cross-sectional view of a joint portion in which loop lines are obliquely provided.

FIG. 9 is a cross-sectional view of a joint portion that bends a loop line in a vertical direction.

[Explanation of symbols]

 1 Precast concrete floor slab 2 Main girder 3 Joint part 4 Step part 4a Recessed part 5 Notched part 5b Loop joint bar 7 Expandable mortar

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuo Tanaka 6-3-1, Takinogawa, Kita-ku, Tokyo Within Kawata Construction Co., Ltd. (72) Inventor Haruo Matsukawa 6-3-1, Takinogawa, Kita-ku, Tokyo Kawada Construction Co., Ltd.

Claims (4)

[Claims] 1. A precast concrete floor slab arranged on a girder is provided with a stepped portion on its end face and a cutout portion is provided in a part thereof, and a shearing force transmitting member is installed in a gap between the facing stepped portions, and Floor joints that connect the distribution reinforcing bars and form loop-shaped tips at the ends are provided so as to project from the side surfaces of the facing notches, and the steps and notches are filled with expansive mortar to adjoin the floor slabs. A joint structure for precast concrete floor slabs, which is characterized by connecting together. 2. The joint structure for a precast concrete floor slab according to claim 1, wherein the shearing force transmitting member is a slip-preventing member protruding from the side surfaces of the facing step portions. 3. The shearing force transmitting member, wherein the tip end of an upper force distribution reinforcing bar projecting from one step portion is formed in a loop shape and bent downward, and a lower part projecting from the other opposing step portion. The joint structure for a precast concrete floor slab according to claim 1, wherein the tip of the reinforcing bar is formed in a loop shape and bent upward, and the expansive mortar is filled in a state where these bent loop reinforcing bars are superposed. . 4. The shearing force transmitting member is a shearing key formed by arranging a spiral reinforcing bar in a recess provided so as to face the step portion and filling it with expansive mortar. Joint structure of precast concrete floor slab.