JP2006274736A - Construction method for pc floor system and pc floor system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method for a PC floor system capable of eliminating necessity of reexamination of main beam strength and shortening construction term. <P>SOLUTION: This PC floor system 11 incorporating a reinforcing fitting 17 composed of a box 17a having a shape similar to a box pulling-out part 11a, proper number of bulkheads 17b for partitioning the inside of the box 17a, and a stud 17c provided on an outer peripheral face of the box 17a in the box pulling-out part 11a is constructed on a main beam 1 from an end side on one side. After constructing a lining board 3 on the constructed PC floor system 11 directly, a crawler crane 4 is moved and is installed on the lining board 3. The work for constructing the PC floor system 11 on a front side of the PC floor system 11 constructed previously by the installed crawler crane 4 is sequentially repeated. Since predetermined punching shearing proof stress can be ensured without reducing punching shearing strength, the PC floor system is not broken by punching shearing force even if the crawler crane moves on the lining board by merely constructing the lining board in an upper part of the PC floor system to perform construction work very efficiently in a short period of time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a construction method of a precast floor slab (hereinafter referred to as “PC floor slab”) used as a floor slab of a road bridge, for example, and a PC floor slab used when implementing this construction method. .

For example, when laying a PC floor slab on a road bridge, various construction methods are implemented. An example is shown in FIG. In the construction method shown in FIG. 9, first, after installing the track 2 and the lining plate 3 on the constructed main girder 1 and assembling the frame equipment, a heavy machine such as a crawler crane 4 is arranged on the frame equipment, The PC floor slab 6 transported by the trailer 5 is sequentially installed.
Efficient installation of precast PC slabs (installation method using both a crawler crane and a carriage), "Kawada Technique", VOL.22, January 1, 2003, pp. 106-107

Further, the main girder and the PC slab are joined by forming a box opening in the PC floor slab, filling the stud gibber on the flange on the main girder in the box opening, and then filling with mortar or the like. However, no reinforcing metal fittings or the like were provided at the box-opening portion.
JP-A-10-96209

  The construction method of Non-Patent Document 1 works by placing heavy machinery and trailers on the PC floor slab, so work efficiency is good, but installation of frame facilities such as tracks on the main girder so as not to damage the PC floor slab. There is a need to. However, when a frame facility such as a track is provided, a load that is not taken into consideration at the time of design acts on the main girder, so that it is necessary to examine the main girder strength again. Moreover, since installation work and removal work of frame equipment such as tracks are required, there is a problem that the construction period becomes long.

  In addition, it is possible to install only the lining plate on the PC floor slab without assembling the frame equipment and allow the crawler crane to move on it. In PC floor slabs that are not provided with reinforcing metal fittings or the like, the PC floor slab may be punched and shear broken due to a drop in the punching shear strength at the box punching portion, which has not been realized.

  The problem to be solved by the present invention is that in the conventional construction method of PC floor slabs, it is necessary to examine the strength of the main girder again, and for the installation work and the removal work of the frame equipment such as the track, There is a problem that the lengthens.

The construction method of the PC floor slab of the present invention is as follows:
There is no need to examine the main girder strength again, and in order to shorten the construction period,
After laying a PC floor slab on one side of the main girder and laying a lining board directly on the PC floor slab,
Move the crawler crane and install it on this laid lining plate,
The most important feature is that the work of laying the PC floor slab is sequentially repeated on the front side of the previously installed PC floor slab by the installed crawler crane.

The PC floor slab of the present invention is
The PC floor slab used for the construction method of the PC floor slab of the present invention,
In order to prevent the PC floor slab from being punched and sheared, even if the crawler crane travels only on the PC floor slab without the frame equipment being assembled,
The first PC deck is
In the box opening part,
A box similar in shape to this box opening part,
An appropriate number of partitions separating the inside of the box;
It was equipped with a reinforcing metal fitting made of a stud provided on the outer peripheral surface of the box,
Or
The second PC deck is
In the longitudinal direction of the box opening part,
A plurality of plates arranged in parallel;
The most important feature is that a reinforcing metal fitting made of concrete reinforcing bars provided on these plates is installed.

  In the PC floor slab, when a steel pipe is welded in the axial direction on the upper surface of a nut / bearing plate screwed into a height adjusting bolt, and a shear reinforcement is welded to the outer peripheral surface of the steel pipe, reinforcement against punching shear failure Therefore, the bearing surface force can be reduced by dispersing the load inside the PC floor slab.

  In the present invention, a predetermined punching shear strength can be secured without lowering the punching shear strength, so the crawler crane moves on the siding plate simply by laying the lining plate directly on the PC floor slab. Even so, the PC slab is not punched and sheared, and the installation work of the PC slab can be carried out very efficiently in a short time.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.
FIG. 1 is an explanatory diagram of the construction method of the present invention, FIG. 2 is a diagram for explaining the positional relationship between the PC floor slab and the height adjusting bolt, FIG. 3 is a diagram for explaining shear fracture occurring in the PC floor slab, and FIG. FIG. 5 is a diagram for explaining the shear deformation due to the vicinity of the load being pushed down, FIG. 5 is a diagram for explaining the transmission of the shear force when the box opening is in the middle of the boundary surface of the shear fracture, and FIG. 6 is a weak point of the box opening. FIGS. 7 and 8 are diagrams illustrating examples of reinforcing metal fittings provided in the box opening portion of the PC floor slab of the present invention, which are suitable for use in the construction method of the present invention.

The construction method of the PC floor slab according to the present invention aims to further improve the work efficiency of the construction method described in Non-Patent Document 1 above.
That is, in the PC floor slab erection method of the present invention, the PC floor slab 11 is carried on the main girder 1 from one end side of the main girder 1 and is installed. Unlike the construction method, as shown in FIG. 1, the lining plate 3 is laid directly on the laid PC floor slab 11.

  Then, the crawler crane 4 is moved and installed on the laid lining plate 3, and the installed crawler crane 4 lays the PC floor slab 11 transported by the trailer 5 forward by the overhanging method. The work to be performed is sequentially performed up to the other end of the main beam 1.

  By the way, in the erection method of the present invention, the crawler crane 4 is, for example, one having a weight capacity of 100 tons and its own weight of about 106 tons as used in the erection method described in Non-Patent Document 1. . Therefore, when the weight of the PC floor slab 11 to be lifted is 24 tons and the lifting balance is 2.5 tons, a total weight of 132 tons acts on the laid PC floor slab 11.

  Further, from the size of the PC floor slab 11 and the crawler crane 4 used in the construction method of the present invention, as shown in FIG. 2A, the vicinity of the four height adjusting bolts 12 that support the crawler crane 4 In addition, the box opening portion 11a for storing the stud is located.

  In this case, the load acting on the single height adjusting bolt 12 is 53.4 tons in consideration of the uneven load, and the PC floor slab 5 of the conventional design in which the reinforcing metal fittings are not provided in the box opening portion. Then, it was considered that the punching shear fracture.

As the shear failure of the PC floor slab 11, two types of shear failure can be considered as shown in FIG. One is a shear failure caused by a load P _L acting like a beam, and one is a punching shear failure occurring when a load P _P penetrates the structure. Incidentally, S1 in FIG. 3 shear deformation caused by the load P _L, S2 denotes a punching shear deformation caused when a load P _P penetrates the structure.

Among them, as shown in FIG. 4, the punching shear fracture due to penetration is caused by the fact that the shear deformation S2 due to the fact that the vicinity where the load _PP is applied is pushed down (compressive load) is adjusted in height as shown in FIG. It is generated by being generated around a nut / supporting plate (hereinafter simply referred to as a supporting plate) 13 screwed into the bolt 12.

  As shown in FIG. 3, the compressive load acting on the bearing plate 13 propagates vertically in the PC floor slab 11 at first, but immediately spreads in the direction of about 45 degrees. Then, at the distributed boundary surface, shear deformation S2 occurs and shear crack Sc occurs. As the shear cracks Sc continue, punching shear fracture occurs. The angle of the boundary surface of this shear fracture progresses while changing from the initial 45 degrees to about 30 degrees.

  Here, if the box-cutting portion 11a is in the middle of the boundary surface of the shear fracture, the shear deformation is interrupted at that portion as shown in FIG. 5, and the shearing force is transmitted along the surface of the box-cutting portion 11a. . Further, the punching deformation pushes down the surface of the box cutting part 11a. Therefore, as indicated by an imaginary line in FIG. 5, it is considered that the box is shear-deformed, and the box end member is shear-deformed by the rigidity reduction of the box-extracting portion 11a, resulting in shear fracture.

The point in carrying out the erection method of the present invention lies in how to compensate for the weak point of the box opening portion 11a. Basically, the following two measures are required.
(1) Insert a member capable of supplementing the rigidity of the internal space of the box opening portion 11a and transmitting a shearing force to the internal space.
(2) Arrange shear reinforcement bars to prevent punch shear.

  FIG. 6 shows one of the countermeasures of the present invention. Here, the steel pipe 14 is first welded to the upper surface of the bearing plate 13 screwed into the height adjusting bolt 12 in the axial direction, and the shear reinforcement bars 15 are radially welded to the outer peripheral surface of the steel pipe 14. There are two possible functions of the shear reinforcement 15 as follows.

  The first is to reinforce the shear fracture surface by placing the reinforcement so as to straddle the punched shear fracture surface, and the second is to apply the force from the bearing plate 13 to the PC floor slab 11. Instead of transmitting only from the lower surface of the steel plate, the force is distributed inside the concrete of the PC floor slab 11 via the shear reinforcement 15 to reduce the support pressure of the support plate 13.

  In general, around the steel pipe 14, particularly just below the bearing plate 13, tensile stress is generated in the concrete of the PC floor slab 11 due to the Poisson effect with respect to the bearing pressure, and cracks may occur. FIG. 2 shows a steel tube 14 in which a coiled restraint reinforcing bar 16 is arranged and reinforced.

Next, the reinforcement structure of the box opening part 11a of the PC floor slab 11 of this invention used when implementing the construction method of this invention is demonstrated.
FIG. 7 shows an example of the reinforcing bracket 17 provided in the box opening portion 11a of the PC floor slab 11 of the present invention.

  In order to reinforce the rigidity of the hollowed-out concrete portion in order to form the box opening portion 11a in the PC floor slab 11, the reinforcing metal fitting 17 has an outer shape similar to the box opening portion 11a. A partition wall 17b for shear reinforcement is attached inside 17a. The number of the partition walls 17b depends on the number of studs 17c described later. However, the number of the partition walls 17b can be reduced if the thickness of the partition walls 17b can be sufficiently secured.

  The outer surface of the box 17a is welded with a reinforcing bar or stud 17c to enhance adhesion to the concrete, and the function of transmitting the shearing force on the side of the height adjusting bolt 12 to the concrete on the opposite side of the box 17a using these. I also have.

  As shown in FIG. 6A, the reinforcing metal fitting 17 and the upper surface of the steel pipe 14 are made smaller than the height of the PC floor slab 11, as shown in FIG. Since the lower surface is filled with non-shrink mortar, it may be the same surface as the lower surface.

  8 is obtained by removing the longitudinal side surface of the box 17a of the reinforcing metal fitting 17 shown in FIG. 7 and replacing it with, for example, two shape-retaining reinforcing bars 17e arranged one above the other for the purpose of cost reduction. It is said.

  That is, the reinforcing metal fitting 17 shown in FIG. 8 holds the shape by arranging the shape-retaining reinforcing bars 17e above and below an appropriate number of inverted trapezoidal plates 17d having a width that can penetrate into the concrete. The plate 17d is provided with a concrete fixing reinforcing bar 17f, and a shearing force is borne by the inverted trapezoidal plate 17d.

  Note that the reinforcing metal fitting 17 shown in FIG. 8 does not use the shape-retaining reinforcing bar 17e, and inserts, for example, styrofoam or corrugated cardboard between the plates 17d, and constructs it in the box opening portion 11a, and inserts it after hardening the concrete. However, it may be formed by extracting foamed polystyrene or cardboard.

  The present invention is not limited to the above examples, and it is needless to say that the embodiments may be appropriately changed within the scope of the technical idea described in each claim.

  The present invention can be applied not only to road bridges but also to buildings.

It is explanatory drawing of the construction method of this invention. It is a figure explaining the positional relationship of a PC floor slab and a height adjustment bolt, (a) is a top view, (b) is a detailed sectional view of the height adjustment bolt vicinity. It is a figure explaining the shear fracture | rupture which generate | occur | produces in PC floor slab. It is a figure explaining that the shear deformation by the vicinity of a load pushing down arises around the bearing plate screwed in the height adjustment bolt. It is a figure explaining the transmission of the shear force when there is a boxing part in the middle of the boundary surface of shear fracture, (a) is a sectional view and (b) is a top view. It is a figure explaining the countermeasure which compensates the weak point of a box extraction part, (a) is sectional drawing, (b) is a top view. It is the figure which showed an example of the reinforcement metal fitting provided in the box opening part of the PC floor slab of this invention suitable for using for the construction method of this invention. It is the figure which showed the other example of the reinforcement metal fitting provided in the box opening part of the PC floor slab of this invention suitable for using for the construction method of this invention. It is a figure explaining the construction method of the conventional PC floor slab.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main girder 3 Covering board 4 Crawler crane 11 PC floor slab 11a Box extraction part 12 Height adjustment bolt 13 Supporting plate 14 Steel pipe 15 Shear reinforcement 17 Reinforcement metal fitting 17a Box 17b Partition 17c Stud 17d Plate 17e Shape-retaining reinforcement 17f Reinforcing bar

Claims (4)

After laying a PC floor slab on one side of the main girder and laying a lining board directly on the PC floor slab,
Move the crawler crane and install it on this laid lining plate,
A construction method of a PC floor slab characterized by sequentially repeating the work of constructing a PC floor slab on the front side of the PC floor slab previously installed by the installed crawler crane. In the box opening part,
A box similar in shape to this box opening part,
An appropriate number of partitions separating the inside of the box;
The PC floor slab used for the construction method according to claim 1, wherein a reinforcing metal fitting comprising a stud provided on an outer peripheral surface of the box is internally provided. In the longitudinal direction of the box opening part,
A plurality of plates arranged in parallel;
The PC floor slab used for the construction method according to claim 1, wherein a reinforcing metal fitting made of concrete fixing reinforcing bars provided on these plates is provided. The PC floor slab according to claim 2 or 3, wherein a steel pipe is welded in an axial direction to an upper surface of a nut / bearing pressure plate screwed into a height adjusting bolt, and a shear reinforcement is welded to an outer peripheral surface of the steel pipe. .

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