JP2003166216A - Synthetic floor slab and construction method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic floor slab for a bridge constructed in the field which is excellent in fatigue durability and low in cost and in which welded structures are not used for steel forms and problems of deflection are not caused when fresh concrete is placed in the site, and its construction method. <P>SOLUTION: Bolt fitting holes are formed in a steel sheet 4 at a specified pitch in its lengthwise and breadthwise directions in advance, and U-shaped bolts 5 are fixed in the holes by nuts 8 so that the round sections of the bolts 5 are set upwards and the angle formed between the linear line connecting both front ends of the screw parts of the U-shaped bolts 5 and the breadthwise direction is at most 45° to make a steel form 3. Then, reinforcements 6 are arranged in the steel form 3, the reinforcements 6 are jointed to the U-shaped bolts 5, after that, it is hooked over main girders 1 and then concrete 7 is placed thereon. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite floor slab for bridges, which is made by placing concrete on a steel formwork produced by on-site construction, and a method for constructing the same.

[0002]

2. Description of the Related Art Conventional synthetic floor slabs constructed in the field are manufactured by welding auxiliary steel to a steel plate called a bottom steel plate in a factory to produce a steel form, which is then transported to the site. It is generally formed by straddling the main girder, placing reinforcing bars, and then placing concrete. The purpose of welding the supplementary steel material to the bottom steel plate is to secure the bending rigidity of the steel form and to reduce the deflection. However, since this steel formwork has a welded structure, cracks may occur in the bottom steel plate from the weld toe, and
It was pointed out that the presence of the supplementary steel material complicates the structure of the steel form, impairs the filling property of concrete, and causes cracks in the concrete at an early stage due to the filling defect, and there is a problem of lacking fatigue durability. Further, the welding work in the factory requires a high skill because it requires skill, and the production cost of the steel formwork is high.

Further, in Japanese Unexamined Patent Publication No. 9-21114, a composite floor slab that does not require welding work is formed by attaching high-strength bolts to a bottom steel plate at predetermined intervals by friction welding and then placing concrete. Precast floor slabs are disclosed. This precast floor slab is one in which concrete is cast on the formwork at the factory to integrate the concrete and the bottom steel plate to make it almost a finished product, and then it is transported to the site for final laying. In addition, since the concrete is solidified and then laid over the main girder, the problem of bending of the bottom steel plate does not occur, but there is a problem that the transportation cost increases.

In Japanese Examined Patent Publication No. 7-26450, a floor slab (called a half precast floor slab) made by pouring concrete at a part of the total thickness in a factory is called. A method of constructing a synthetic floor slab by laying it and placing concrete of the remaining thickness on it is disclosed. According to this method, since flexural rigidity has already been secured by using the half precast floor slab, there is no problem of deflection when fresh concrete is placed at the site, but both at the factory and at the site. Since it requires concrete pouring work, problems such as extension of construction period and cost increase occur.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fatigue endurance which does not cause the problem of bending when fresh concrete is placed on site without using a welded structure for the steel form. An object of the present invention is to provide a synthetic floor slab for on-site construction which is excellent in properties and low cost, and a construction method thereof.

[0006]

SUMMARY OF THE INVENTION The present invention reduces deflection at the time of placing fresh concrete by using a steel form frame having a high bending rigidity, which is made of a general-purpose product without using welding at all. It is characterized by the following, and its gist is as follows.

The invention of claim 1 is a synthetic floor slab formed by on-site construction, which comprises a steel formwork bridged between main girders and concrete cast into the steel formwork. A steel plate in which the steel formwork is provided with bolt mounting holes in the vertical and horizontal directions of the steel plate at a predetermined pitch in advance, and a U-shaped bolt fixed to the bolt mounting hole with a nut with the non-threaded part facing up And the angle formed by the straight line connecting both ends of the threaded portion of the U-shaped bolt and the bridge width direction is 45 ° or less.

The invention of claim 2 is further characterized in that the U-shaped bolts are arranged on a plurality of straight lines which are parallel to the bridge width direction and are spaced at predetermined intervals. Is.

A third aspect of the present invention is the synthetic floor slab according to the second aspect, further comprising a shear reinforcement member arranged on the U-shaped bolt.

According to a fourth aspect of the invention, the shear reinforcement material is L.
The synthetic floor slab according to claim 3, wherein the synthetic floor slab is a V-shaped steel, and a horizontal portion of the L-shaped steel is arranged in contact with the steel plate.

The invention of claim 5 uses a U-shaped bolt or a V-shaped bolt instead of the U-shaped bolt.
The synthetic floor slab according to any one of items 1 to 4.

According to a sixth aspect of the present invention, in the synthetic floor slab according to any one of the first to fifth aspects, the steel plate is provided with irregularities on the concrete placing surface side. is there.

The invention of claim 7 is the synthetic floor slab according to any one of claims 1 to 5, wherein the steel plate is a striped steel plate.

The invention of claim 8 is characterized in that an enlarged portion having a diameter larger than the diameter of the bolt mounting hole is provided in the non-threaded portion of the U-shaped bolt. The synthetic floor slab according to item 1.

According to a ninth aspect of the present invention, the non-threaded portion of the U-shaped bolt or the V-shaped bolt is provided with an enlarged portion having a diameter larger than the diameter of the bolt mounting hole. 5 is a synthetic floor slab.

According to a tenth aspect of the present invention, the expanded portion has a tapered shape in which the diameter increases from the threaded portion side toward the non-threaded portion side, and the synthetic floor slab according to claim 8 or 9, Is.

According to an eleventh aspect of the present invention, a U-shaped bolt is placed in the bolt mounting hole with its non-threaded portion facing upward, with respect to the steel plate in which bolt mounting holes are provided in advance in the vertical and horizontal directions of the steel plate at predetermined pitches. And, a steel form is produced by fixing with a nut so that the angle formed by the straight line connecting the both ends of the threaded portion of the U-shaped bolt and the bridge width direction is 45 ° or less, and thereafter,
It is a method for constructing a synthetic floor slab, characterized in that it is bridged between main girders and concrete is placed on the steel form.

According to a twelfth aspect of the present invention, a U-shaped bolt is placed in the bolt mounting hole with its non-threaded portion facing upward, with respect to the steel plate in which bolt mounting holes are preliminarily provided in the longitudinal and lateral directions of the steel plate at predetermined pitches. In addition, a steel mold is manufactured by fixing with a nut so that the angle formed by the straight line connecting both ends of the threaded portion of the U-shaped bolt and the bridge width direction is 45 ° or less, and the steel mold is manufactured. Reinforcing bars are arranged, the reinforcing bars and the U-shaped bolts are joined together at the tops of the U-shaped bolts, and then they are bridged between main girders, and concrete is placed on the steel formwork. This is a method of constructing a synthetic floor slab.

According to a thirteenth aspect of the present invention, the U-shaped bolts are further arranged on a plurality of straight lines which are parallel to the width direction of the bridge and are spaced at predetermined intervals. It is the method of construction of the plate.

According to a fourteenth aspect of the present invention, a shear reinforcement member is attached to the U-shaped bolt after the steel form is manufactured and before the steel form is bridged between main girders. It is the construction method of the synthetic floor slab according to claim 13 characterized by the above.

According to a fifteenth aspect of the present invention, a plurality of U-shaped bolts are fixed to a reinforcing bar by welding at a predetermined pitch in advance, and the plurality of U-shaped bolts are fixed to a steel plate in which bolt mounting holes are provided at the predetermined pitch. It is characterized in that the non-screw part of the U-shaped bolt is turned up and fixed with a nut to produce a steel form, which is then bridged between main girders and concrete is placed on the steel form. It is a construction method of a synthetic floor slab.

According to a sixteenth aspect of the present invention, a plurality of U-shaped bolts are previously fixed to a shear reinforcement member by welding at a predetermined pitch, and the steel plate is provided with bolt mounting holes at the predetermined pitch. A plurality of U-shaped bolts are fixed with nuts so that the non-screwed portions are upwards to produce a steel form, another reinforcing bar is arranged on the steel form, and the other reinforcing bar and the U-shaped bolt are arranged. Is connected to the main girder, and then concrete is placed in the steel formwork, which is a method for constructing a synthetic floor slab.

According to a seventeenth aspect of the present invention, a steel plate having bolt mounting holes preliminarily provided at predetermined pitches in the longitudinal and lateral directions of the steel plate is provided with L-shaped steels having bolt insertion holes matching the bolt mounting holes. The holes are aligned with each other, and the U-shaped bolts are placed in these holes with their non-threaded parts facing up, and fixed with nuts to produce a steel mold, and a steel bar is attached to the steel mold. It is a method for constructing a synthetic floor slab, which comprises arranging the reinforcing bars and the U-shaped bolts, connecting the reinforcing bars and the U-shaped bolts, then bridging them between main girders, and placing concrete on the steel form.

The invention of claim 18 uses a U-shaped bolt or a V-shaped bolt in place of the U-shaped bolt.
It is a construction method of the synthetic floor slab described in any one of 1 to 17.

The invention according to claim 19 is characterized in that the steel sheet is further provided with concavities and convexities on at least one surface thereof, and the surface provided with the concavities and convexities faces upward. The method for constructing a synthetic floor slab according to item 1.

According to a twentieth aspect of the present invention, an enlarged portion having a diameter larger than the diameter of the bolt mounting hole is provided on the non-threaded portion of the U-shaped bolt, and the U-shaped bolt is fixed to the bolt mounting hole. At this time, the enlarged portion is fixed while being pressed against the bolt mounting hole.
It is a construction method of the synthetic floor slab as described in any one of [18].

According to the inventions of claims 1, 11 and 12, U
The angle between the straight line connecting both ends of the threaded portion of the V-shaped bolt and the bridge width direction is set to 45 ° or less, and the steel plate is attached to the steel plate, fastened with the rebar, joined, and fixed. The secondary moment increases, the bending rigidity increases, and the deflection due to the weight of the placed fresh concrete is reduced. Further, by mounting the U-shaped bolt with the non-threaded portion (R portion) facing upward, the U-shaped bolt plays the role of a dowel and contributes to the integration of the steel plate and the concrete. Further, since the U-shaped bolt is fixed to the steel plate with the nut, no welding work is required.

According to the invention of claims 2 and 13, since the U-shaped bolts are arranged on a straight line parallel to the bridge width direction,
The main reinforcing bar can be joined and fixed to the non-threaded portion (R portion) of a large number of U bolts, which increases the bending rigidity of the steel sheet and reduces the deflection due to the weight of fresh concrete.

According to the inventions of claims 3, 4, 14, 16 and 17, since the shear reinforcing material is arranged on the U-shaped bolt, the bending rigidity of the steel plate is further enhanced and the deflection due to the weight of fresh concrete is further reduced. it can.

According to the invention of claims 5 and 18, even if a U-shaped bolt or a V-shaped bolt is used instead of a commercially available U bolt (U-shaped bolt) that can be obtained at low cost, The same effect can be obtained.

Here, as shown in FIG. 8, the hole diameter of the bolt mounting hole 41 provided in the steel plate 4 is usually slightly larger than the shaft diameter of the bolt 5. Therefore, there is a gap 11 called a clearance between the bolt 5 and the bolt mounting hole 41. Therefore, although the bolt 5 is fixed to the steel plate 4 from above and below by the nut 8 and fixed (friction joining), if the tightening force is not sufficient, the concrete 7 is solidified and then horizontal shearing force is applied to the concrete 7. Horizontal load is transmitted to the bolt 5 via the
May be shifted from the steel plate 4 in the horizontal direction by a maximum amount of the play gap 11. As a result, the steel plate 4 and the concrete 7 may be displaced from each other.

On the other hand, when designing a composite floor slab, it is designed so that there is no gap between the steel plate and the concrete,
Deformation and stress are calculated. Therefore, if a deviation occurs between the steel plate and concrete due to the deviation of the bolts as described above, not only the mechanical characteristics such as the rigidity as designed cannot be obtained, but also due to the repeated load. Since it is repeatedly deformed, fatigue deterioration may be promoted inside the concrete.

Therefore, according to the inventions of claims 6, 7 and 19, the unevenness is provided on the concrete casting surface side of the steel plate, so that after the concrete is solidified, the steel plate and the concrete are integrated through the unevenness. Therefore, even if a horizontal shear load is applied to the composite floor slab, the load transmitted to the bolt is small, and the displacement of the bolt with respect to the steel plate is prevented. As a result, the steel plate and the concrete can be more surely integrated (synthesized), and desired mechanical properties such as rigidity can be secured.

According to the present invention, the non-threaded portion of the U-shaped bolt is provided with an enlarged portion having a diameter larger than the diameter of the bolt mounting hole. Since the portion can be fixed while being pressed into the bolt mounting hole, the U-shaped bolt (or the U-shaped bolt or the V-shaped bolt) is fixed in a state of being bitten into the bolt mounting hole. As a result, the bolt is not displaced with respect to the steel plate, so that the displacement between the steel plate and the concrete can be prevented.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

[Embodiment 1] FIG. 1 is a view of a bridge using a composite floor slab according to an embodiment of the present invention. FIG. 2 is a diagram showing details of the synthetic floor slab according to the embodiment of the present invention, (a)
Is a cross-sectional view in the bridge width direction, and (b) is a cross-sectional view in the bridge axis direction.

As shown in FIG. 1, the bridge using the composite floor slab according to the present invention has a steel form frame with reinforcements (4, 5, 6, 8 assembled on site). (State), after installing this on a pair of main girders 1, concrete 7 is poured to form a synthetic floor slab 2 for construction. As the main girder 1, a plate girder with an I cross section, a box girder with a closed cross section, or a box girder with an open cross section is used recently. In the synthetic floor slab 2, a U-shaped bolt 5 is attached to a steel plate (bottom steel plate) 4 to form a steel form frame 3, and a reinforcing bar 6 (main reinforcing bar 61, distribution reinforcing bar 62) is arranged on the steel form frame 3. And this is a pair of main girders 1
It is formed by pouring concrete 7 after it is laid over it.

Details of the steel mold 3 are shown in FIGS. 2 (a) and 2 (b).
As shown in, the U-shaped bolt 5 is formed in the bolt mounting hole 41 of the steel plate 4 by tightening the nut 8 with the non-threaded portion (R portion) 51 facing upward. Bottom steel plate 4
For example, a commercially available plain carbon steel plate is used, and a bolt mounting hole 41 is formed in the factory beforehand by drilling or laser cutting or the like. This bolt mounting hole 41 is used for both screw parts 5 of the U-shaped bolt 5 to be used.
It is assumed that a pair of holes is formed at an interval equal to the interval P of 2 and the pair of holes are arranged in the entire bottom steel plate 4 in the vertical and horizontal directions of the bottom steel plate 4 at a predetermined pitch. Further, the mounting direction of the U-shaped bolt 5 to the bottom steel plate 4 should be such that the tips of both screw parts 52 of the U-shaped bolt 5 are fixed so that the bending rigidity of the steel form 2 is increased. The connecting straight line is 4 with the width direction of the bridge.
It is preferable to arrange the pair of holes such that the angle is 5 ° or less, more preferably 30 ° or less, and further preferably 15 ° or less, and the U-shaped bolt 5 is approximately 0 °, that is, as shown in FIGS. It is particularly preferable to mount the bottom steel plate 3 so that the straight line connecting the tips of the two threaded portions 52 is parallel to the bridge width direction because the bending rigidity of the bottom steel plate 3 can be most effectively enhanced. As described above, the reason why it is preferable to decrease the angle formed by the straight line connecting the ends of the screw portions 52 of the U-shaped bolt 5 with the bridge width direction is as follows.
It is as follows. That is, the smaller the angle formed by the straight line connecting the tips of the two threaded portions 52 of the U-shaped bolt 5 with the bridge width direction, the shorter the span distance based on the main reinforcing bars 61 arranged along the straight line. This is to reduce the deflection of the entire steel form 3.

After fixing the U-shaped bolt 5 to the bottom steel plate 4 with the nut 8, a main reinforcing bar 61 and a distribution reinforcing bar 62 are arranged above the bottom steel plate 4 as shown in FIGS. 2 (a) and 2 (b), for example. Then, these may be fixed to the non-screwed portion (R portion) 51 of the U-shaped bolt 5 by, for example, the number wire 9. Usually, the main reinforcing bars 61 are arranged parallel to the bridge width direction, and the distribution reinforcing bars 62 are arranged parallel to the bridge axis direction. As a result, the main rebar 61 is brought into a state close to the pin connection at the U-shaped bolt 5 and the number line 9 along the bridge width direction, so that the bending rigidity of the steel form 3 is increased. Therefore, as shown in FIG. 1, the U-shaped bolt 5
Are arranged on a plurality of straight lines parallel to the bridge width direction and at a predetermined interval, the number of binding points (the number of pin connections) between the main rebar 61 and the U-shaped bolt can be increased, so that the bending rigidity of the steel form 3 is increased. Can be raised.

The U-shaped bolt 5 is not particularly limited in its shape and size, but it is preferable to use a commercially available U bolt which can form the steel mold 3 at low cost and which is easily available and inexpensive. Alternatively, instead of the U-shaped bolt 5, a U-shaped bolt or a V-shaped bolt can be used to obtain the same effect.

The size of the U-shaped bolts 5 (or U-shaped bolts or V-shaped bolts) to be used, the mounting pitch, the mounting direction, etc. on the bottom steel plate 4 are determined by using, for example, numerical analysis by the existing finite element method. The amount of flexure of the steel form 3 at the time of placing the fresh concrete is calculated by appropriately changing the variables such as the size, the pitch, and the mounting direction, and the required accuracy of the composite floor slab 2 to be constructed depends on the amount of flexure and the like. From the satisfied combination of the above variables, the U-shaped bolt 5 is attached to the bottom steel plate 4
It can be determined by selecting a suitable combination in consideration of workability at the time of attaching to.

After arranging the reinforcing bars 61 and 62 on the steel form 3 formed by attaching the U-shaped bolt 5 to the bottom steel plate 4 as described above, the fresh concrete 7 is placed on the steel form 3. By doing so, since the bending rigidity of the steel form 3 is enhanced, the deflection of the steel form 3 due to the weight of the fresh concrete 7 is small, and the synthetic floor slab 2 can be formed with high construction accuracy.

Although the U-shaped bolt 5 can be mounted in the factory, the steel plate 4 in which only the bolt mounting hole 41 is drilled in the factory is not assembled with the U-shaped bolt 5 and the reinforcing bar 6. It is easier to transport and assemble on site because it is easier to transport to the site and assemble on site,
It is more preferable because the transportation cost can be reduced. In addition, since the framing is easy, the manufacturing cost can be reduced.

In addition, in the factory, a plurality of U-shaped bolts 5 are previously prepared.
It is further preferable that the reinforcing bar 6 is fixed to the steel bar 6 by welding at a pitch that matches the bolt mounting holes 41 of the steel plate 4, and the reinforcing bar 6 is transported to the site and attached to the steel plate 4 on the site. As a result, the on-site construction period can be further shortened and the manufacturing cost can be further reduced.

In the above, in the factory, a plurality of U-shaped bolts 5
When fixing the to the rebar 6 by welding, the U-shaped bolt 5
It is difficult to align the mounting directions of the plurality of U-shaped bolts 5 with the method of welding to the reinforcing bar 6 only at the top of the above, and the workability is likely to deteriorate. Therefore, the U-shaped bolt 5
It is preferable to adopt a method of spot-welding a reinforcing bar (which is referred to as an “assembled reinforcing bar”) to both of the middle legs. Then, after this is locally attached to the steel plate 4, the main reinforcing bar 61 and the distribution reinforcing bar 62 may be fixed to the top of the U-shaped bolt 5 by welding.

Instead of the assembled rebar, a flat bar or L
A shear reinforcing material such as a V-shaped steel (L-shaped steel) may be used. When the flat bar is used, the plate surfaces of the flat bar 12 may be brought into contact with the middle legs of the U-shaped bolt 5 and welded (see FIG. 10A). As a result, the mounting directions of the U-shaped bolts 5 can be aligned more easily and more accurately than in the case of using the assembled rebar, and the workability is further improved. Further, since the flat bar 12 is fixed to the U-shaped bolt 5 by welding, the shear deformation of the steel plate 4 can be further reduced.

The shear reinforcing material may be attached after the U-shaped bolt and the steel plate are integrated.

When an L-shaped steel is used as the shear reinforcing material, a bolt insertion hole which matches the bolt mounting hole 41 of the steel plate 4 is provided in the horizontal portion of the L-shaped steel 13 so that The holes of the U-shaped bolts 5 are made to match each other.
2 may be inserted and fixed integrally with a nut (Fig. 10).
(See (b)). According to this method, it is possible to obtain the effect of reducing the shear deformation of the steel plate 4 similar to the flat bar described above, while making welding work unnecessary for attachment.

[Embodiment 2] As the bottom steel plate 4, it is recommended to use a striped steel plate or the like having unevenness at least on the concrete placing surface side. FIG. 3 is a model diagram for explaining load transfer when a horizontal shear load is applied to the concrete portion after solidification of concrete when a striped steel plate is used as the bottom steel plate 4. Similar to FIG. 8 described above,
The U-shaped bolt 5 is fixed to the steel plate 4 by tightening it with nuts 8 from above and below (in FIG. 3, only the vicinity of the steel plate 4 is shown). A plurality of striped protrusions 42 are provided on the steel plate 4, and the solidified concrete 7 is in close contact with the steel plate 4. Here, when the steel plate is fixed and a horizontal load is applied to the concrete 7, a force (horizontal shearing force) that causes the concrete 7 to shift in the horizontal direction and the projection 4 are applied.
A force (uplift) is generated to try to get over. The horizontal shearing force is supported by the reaction force of the protrusions 4, while the uplift is supported by the reaction force of the gibber action of the U-shaped bolt 5, so that the concrete 7 does not shift or float up from the steel plate 4.

Since the deviation in the horizontal direction is supported by the projection 4, it is not necessary to support the deviation between the bolt 7 and the steel plate only by friction welding, and the tightening force by the nut may be small. For this reason, the U-shaped bolt 5 has
It is not necessary to use expensive materials such as those used for high-strength bolts of No. 21114, and it is possible to use inexpensive ordinary steel U
Bolts can be used.

Incidentally, FIG. 9 shows a model diagram for explaining the displacement behavior of the concrete 7 when a striped steel plate is used as the steel plate 4 and the U-shaped bolt 5 is not used. As shown in FIG. 9, when a horizontal load is applied to the concrete 7, the uplift cannot be supported because there is no U-shaped bolt 5, and the concrete 7 is separated from the steel plate 42 and floats up. It may get over the protrusion 4 and be displaced in the horizontal direction.

Therefore, the combined use of the U-shaped bolt 7 and the striped steel plate 4 makes it possible for the first time to reduce the deflection at the time of pouring fresh concrete and to reliably prevent the deviation of concrete after solidification. .

[Third Embodiment] Instead of using the striped steel plate described above, it is also possible to use a non-threaded portion of the U-shaped bolt provided with an enlarged portion having a diameter larger than the diameter of the bolt mounting hole. For example, as shown in FIG. 6, the U-shaped bolt 5 has a taper portion whose diameter increases from the threaded portion 51 side toward the non-threaded portion 52 side and whose maximum diameter is larger than the diameter of the bolt mounting hole 41. 53 is provided. By fitting the U-shaped bolt 5 into the bolt mounting hole 41 provided in the steel plate 4 and tightening it with the nut 8, the tapered portion 53 is restrained at the upper end portion of the bolt mounting hole 41, and the tapered portion 53 exerts tensile stress. It is fixed in the state of receiving and elastically stretching. Therefore, even if the portion of the concrete 7 after solidification receives a horizontal shearing force, the U-shaped bolt 5 is not displaced from the steel plate 4 and is not lifted up.

The shape of the tapered portion 53 is not limited to that shown in FIG. 6, but for example, as shown in FIG. 7, the maximum diameter side of the tapered portion 53 may have a flange shape.

[0055]

EXAMPLES [Example 1] In order to confirm the effects of the present invention,
Steel formwork according to the present invention (present invention example 1 and present invention example 2)
And a steel form (comparative example) using high-strength bolts, the maximum amount of deflection was calculated by three-dimensional analysis using the finite element method, and comparison was performed. FIG. 5A is an arrow view for explaining the configurations of the present invention example 1, FIG. 5B, the present invention example 2, and FIG.

Steel form 3 of Example 1 of the present invention shown in FIG. 5 (a).
Is a floor steel plate span 6 (thickness 6 mm) (main girder spacing) 2.
The bottom steel plate 4 is a U-shaped bolt 5 with a nominal 150 U-bolt (JIS F 30
22) with the non-threaded portion (R portion) 51 facing upward, and the mounting pitch is 388 mm at the U bolt 5 center interval in the bridge width direction,
It was attached in a 250 mm arrangement in the bridge axis direction.
Further, the mounting direction of the U-bolt 5 was such that the straight line connecting the tips of both threaded portions 52 of the U-bolt 5 was aligned with the bridge width direction. Then, the main reinforcing bar 61 having a diameter of 19 mm and the distribution reinforcing bar 62 having a diameter of 16 mm are arranged in the vertical and horizontal directions of the bottom steel plate 4 so as to be orthogonal to each other in the vicinity of the top of the U bolt 5, and the orthogonal portion is the top of the U bolt 5. It is assumed to be pin-coupled.

Steel form 3 of Example 2 of the present invention shown in FIG. 5 (b).
In the present invention example 1, the arrangement of the U bolts 5 is changed to a zigzag arrangement in which the positions in the bridge width direction of the U bolts 5 adjacent to each other in the bridge axis direction are shifted by a half pitch.

The steel form 3 of the comparative example shown in FIG.
A high strength bolt 10 is used instead of the U bolt 5. 1. A thickness of 6 mm, which is the same as the invention examples 1 and 2, and a floor slab span 2.
A high strength bolt (JIS B 1186) 10 having a standard size of 170 mm and a M24 on a bottom steel plate 4 of 5 m, with the head 101 facing upward, has a mounting pitch of 20 in both the bridge width direction and the bridge axis direction.
It was attached in a square arrangement of 8 mm. And 1
The main reinforcing bar 61 having a diameter of 9 mm and the distribution reinforcing bar 62 having a diameter of 16 mm are arranged in the vertical and horizontal directions of the bottom steel plate 4 so that they are orthogonal to each other at the head 101 of the high-strength bolt 10.
It is assumed that the head 101 of No. 0 is pin-connected.

The bottom steel plate 4, the U bolt 5, the high-strength bolt 10 and the reinforcing bar 6 all had Young's modulus of 206 GPa.

Then, 20 pieces of fresh concrete having a density of 2350 kg / m ³ were placed on each of the steel molds 3 described above.
As a result of calculating the maximum amount of deflection of the steel mold 3 in a state of being cast to a thickness of 0 mm, it was 7.9 mm in Inventive Example 1, 7.2 mm in Inventive Example 2, and 32 mm in Comparative Example.

In Examples 1 and 2 of the present invention, the combination of the bottom steel plate 4, the U-bolt 5, and the main rebar 61 provides a structure similar to a fieldel structure, so that the flexure is suppressed to a small amount with respect to the weight of fresh concrete. I was able to do it.

On the other hand, the bottom steel plate 4 and the high-strength bolt 10 of the comparative example.
The structure in which the main rebar 61 and the main rebar 61 are combined looks like a feeleldeal structure at first glance, but since the connection between the high-strength bolt 10 and the main rebar 61 is a pin connection with no rotation constraint,
The structure is completely different from the feeleldeal structure, and the deflection could not be suppressed small.

Here, the fieldel structure is a structure in which two horizontal upper and lower beam members are rigidly connected by a plurality of vertical members.

Further, in order to confirm the effect of the shear reinforcing material, a flat bar was attached (Invention Example 3) and an L-shaped steel was inserted (Invention Example 4) to the Invention Example 1 described above. For each of the above, the maximum deflection amount was calculated by three-dimensional analysis using the finite element method, as in the above. Figure 1
0 (a) is an arrow view for explaining the configuration of the present invention example 3, and (b) is an arrow view for explaining the configuration of the present invention example 4. Flat bar is FB-
70 × 6 was used and L-shaped steel was L-70 × 70 × 6. As a result of the calculation, the flexure amount in the case of the present invention example 1 in which the shear reinforcement was not used was 7.9 mm, whereas the flexure amount was 3.0 mm regardless of whether the flat bar or the L-shaped steel was used. It was confirmed that the shear deformation prevention effect was great.

Example 2 Striped steel plate (length 2800 mm,
A plurality of bolt mounting holes (pitch 250 mm, hole diameter 14.5 mm) are formed in the longitudinal direction of a width 2500 mm, thickness 6 mm), and commercially available U bolts (without taper portion; JIS F 3022 [ Call 150])
Was fixed with nuts and then concrete (thickness 200 m
m) was cast and solidified to prepare a synthetic floor slab test piece.
This test piece was subjected to a load test (wheel load running test) by a repeated moving load, after which the concrete was removed from the striped steel plate and the surface of the concrete on the side in contact with the striped steel plate was visually observed. As a result, the protrusion marks of the striped steel plate were clearly left on the surface of the concrete, and it is judged that the concrete did not behave as shown in FIG. 9 (over the protrusion repeatedly. In that case, the corners of the projection marks of concrete are worn or destroyed by the projections and the projection marks are not clear).

[Embodiment 3] As the steel plate, not a striped steel plate but an ordinary steel plate having no projection (the size is the same as that of the striped steel plate of the above-mentioned Embodiment 2) is used, and the U-shaped bolt 5 is the above-mentioned embodiment. Although the same size as the normal U-bolt used in 2 except for the shaft diameter, a taper portion 53 (φ12 mm / φ16 mm, length 6 mm) provided on the non-threaded portion 51 immediately above the threaded portion 51 was used ( (See FIG. 6). Further, the hole diameter of the bolt mounting hole was set to 14.5 mm, which is the same as in the second embodiment. After fixing the U bolt 5 in the bolt mounting hole with a nut, concrete (thickness 200 mm) was cast and solidified to prepare a test piece of a synthetic floor slab. A load test (wheel load running test) by repeated moving load was performed on this test piece, and when visually observed after the test, no deviation was observed between the U-bolt 5 and the steel plate, and concrete peeled from the steel plate. No shift was observed.

[0067]

As described above, according to the present invention, the welding work which requires skill can be replaced with the simple drilling work and the fastening work of the U-shaped bolts, etc. It is possible to provide a synthetic floor slab with excellent fatigue durability and a construction method thereof because the synthetic floor slab with less bending of the steel formwork and high construction accuracy with low construction cost is used and a welding structure is not used for the steel formwork.

By using a shear reinforcement material,
The deflection of the steel form can be further reduced.

Further, by using a striped steel plate or a taper-shaped U-shaped bolt, it is possible to prevent the steel plate and the concrete from being displaced. Therefore, in addition to the above effects, the mechanical characteristics such as the rigidity of the synthetic floor slab can be improved. It can be secured more reliably.

[Brief description of drawings]

FIG. 1 is a view for explaining the structure of a synthetic floor slab (Embodiment 1) according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the details of a synthetic floor slab (Embodiment 1) according to the present invention, in which (a) is a cross-sectional view in the bridge width direction,
(B) is a cross-sectional view in the bridge axis direction.

FIG. 3 is a model diagram for explaining load transmission in a composite floor slab (embodiment 2) according to the present invention, where (a) shows no load and (b) shows horizontal load. is there.

FIG. 4 is a model diagram for explaining load transmission in a composite floor slab (embodiment 3) according to the present invention, in which (a) is no load and (b) is a horizontal load. is there.

5A and 5B are views for explaining the structure of the steel mold of Example 1, where FIG. 5A is an example 1 of the present invention, FIG. 5B is an example 2 of the present invention, and FIG.
[Fig. 3] is an arrow view for explaining a configuration of a comparative example.

FIG. 6 is a view showing a U-shaped bolt having a taper portion, which is used in the composite floor slab of Example 3, (a) is a front view,
(B) is a partial front view showing details of the vicinity A of the tapered portion.

7A and 7B show another form of a U-shaped bolt having a tapered portion used in the composite floor slab of Example 3, (a) is an overall front view, and (b) is a portion showing details of the vicinity B of the tapered portion. It is a front view.

FIG. 8 is a model diagram for explaining load transmission in a composite floor slab using friction welding with bolts, (a) showing no load, and (b) showing horizontal load.

FIG. 9 is a model diagram for explaining the behavior of misalignment in a composite floor slab using only striped steel plates without using bolts.

10A and 10B are views for explaining the structure of the steel form of Example 1, wherein FIG. 10A is an arrow view for explaining the structure of Invention example 3 and FIG.

[Explanation of symbols]

1 ... Main girder 2 ... Synthetic floor slab 3 ... Steel formwork 4 ... Steel plate (bottom steel plate) 41 ... Bolt mounting hole 42 ... Protrusion 5 ... U-shaped bolt (U bolt) 51 ... Non-threaded part (R part) 52 ... screw part 53 ... taper part 6 ... Rebar 61 ... Main rebar 62 ... Power distribution rebar 7. Concrete (fresh concrete) 8 ... Nut Line 9 ... 10 ... High-strength bolt 101 ... head 11 ... Yuma 12 ... Flat bar 13 ... L-shaped steel (L-shaped steel)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhiro Okamoto             2-1026 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo               Kobe Steel, Ltd. Kobe Head Office F-term (reference) 2D059 AA17 CC04 GG61

Claims (20)

[Claims] 1. A synthetic floor slab formed by on-site construction, comprising a steel formwork bridged between main girders and concrete cast into the steel formwork, the steel formwork The frame is composed of a steel plate in which bolt mounting holes are provided in advance in the vertical and horizontal directions of the steel plate at a predetermined pitch, respectively, and a U-shaped bolt fixed to the bolt mounting hole with a non-threaded portion facing upward with a nut,
A synthetic floor slab, wherein an angle formed by a straight line connecting both ends of a threaded portion of the U-shaped bolt and a bridge width direction is 45 ° or less. 2. The synthetic floor slab according to claim 1, wherein the U-shaped bolts are arranged on a plurality of straight lines that are parallel to the bridge width direction and are spaced at predetermined intervals. 3. The synthetic floor slab according to claim 2, further comprising a shear reinforcement member disposed on the U-shaped bolt. 4. The shear reinforcement is L-shaped steel,
The synthetic floor slab according to claim 3, wherein a horizontal portion of the L-shaped steel is arranged in contact with the steel plate. 5. The synthetic floor slab according to claim 1, wherein a U-shaped bolt or a V-shaped bolt is used instead of the U-shaped bolt. 6. The steel sheet is provided with irregularities on the concrete pouring surface side thereof.
5. The synthetic floor slab according to any one of 5 above. 7. The synthetic floor slab according to claim 1, wherein the steel plate is a striped steel plate. 8. The non-threaded portion of the U-shaped bolt is provided with an enlarged portion having a diameter larger than the diameter of the bolt mounting hole, according to any one of claims 1 to 4. Synthetic floor slab. 9. The composition according to claim 5, wherein the non-threaded portion of the U-shaped bolt or the V-shaped bolt is provided with an enlarged portion having a diameter larger than the diameter of the bolt mounting hole. Floor slab. 10. The synthetic floor slab according to claim 8, wherein the enlarged portion has a tapered shape whose diameter increases from the threaded portion side toward the non-threaded portion side. 11. A U-shaped bolt with a non-threaded portion facing upward in the bolt mounting hole with respect to the steel plate in which bolt mounting holes are previously provided at predetermined pitches in the vertical and horizontal directions of the steel plate, respectively. A steel form is manufactured by fixing with a nut so that the angle formed by the straight line connecting both ends of the screw part of the bolt and the width direction of the bridge is 45 ° or less, and then the steel form is bridged between the main girders. A method for constructing a synthetic floor slab, which comprises placing concrete on a formwork. 12. A U-shaped bolt having a non-screw portion on its upper side in the bolt mounting hole with respect to the steel plate in which bolt mounting holes are provided in advance in the vertical and horizontal directions of the steel plate at predetermined pitches respectively. A steel formwork is manufactured by fixing with a nut so that the angle formed by the straight line connecting the both ends of the screw part of the bolt and the bridge width direction is 45 ° or less, and the rebar is placed on the steel formwork, A method for constructing a synthetic floor slab, comprising: connecting the reinforcing bars and the U-shaped bolts, then bridging them between main girders, and placing concrete on the steel formwork. 13. The method for constructing a synthetic floor slab according to claim 11 or 12, wherein the U-shaped bolts are arranged on a plurality of straight lines that are parallel to the bridge width direction and are spaced at predetermined intervals. 14. A shear reinforcement member is attached to the U-shaped bolt after the steel form is manufactured and before the steel form is bridged between main girders. The method for constructing a synthetic floor slab according to claim 13. 15. A plurality of U-shaped bolts, which are fixed to a reinforcing bar by welding at a predetermined pitch in advance, are attached to a steel plate in which bolt mounting holes are preliminarily provided at the predetermined pitch. Construction of a steel slab with the non-screwed part facing up and fixing with nuts, then straddling between the main girders and placing concrete on the steel form Method. 16. A plurality of U-shaped bolts are previously fixed to a shear reinforcement member by welding at a predetermined pitch, and the plurality of U-shaped bolts are attached to a steel plate having bolt mounting holes previously provided at the predetermined pitch. A steel mold is produced by fixing the non-screw part of the bolt with a nut, and another reinforcing bar is arranged on the steel mold, and the another reinforcing bar and the U-shaped bolt are coupled to each other,
After that, the method for constructing a synthetic floor slab is characterized in that it is bridged between main girders and concrete is placed in the steel form. 17. An L-shaped steel having a bolt insertion hole that matches the bolt mounting hole is made to match each other with respect to a steel plate in which bolt mounting holes are previously provided at predetermined pitches in the vertical and horizontal directions of the steel plate. And the U-shaped bolts are placed in these holes with the non-threaded parts facing upwards, and fixed with nuts to produce a steel mold, and the reinforcing bars are arranged in the steel mold.
A method for constructing a synthetic floor slab, comprising: connecting the reinforcing bars and the U-shaped bolts, then bridging them between main girders, and placing concrete on the steel formwork. 18. The method for constructing a synthetic floor slab according to claim 11, wherein a U-shaped bolt or a V-shaped bolt is used instead of the U-shaped bolt. 19. The steel sheet according to claim 11, wherein at least one surface of the steel sheet is further provided with unevenness, and the surface provided with the unevenness is directed upward. Construction method of synthetic floor slab. 20. An enlarged portion having a diameter larger than a diameter of the bolt mounting hole is provided on a non-threaded portion of the U-shaped bolt, and the enlarged portion is fixed when the U-shaped bolt is fixed to the bolt mounting hole. The method for constructing a synthetic floor slab according to any one of claims 11 to 18, wherein the portion is fixed while being pressed against the bolt mounting hole.