JP6180376B2 - Main girder provision method in composite girder floor slab replacement method, composite girder floor slab replacement method, and main girder provision structure in composite girder floor slab replacement method - Google Patents

Description

  The present invention relates to a main girder provisional method in a composite girder floor slab replacement construction method for elevated roads, highways, bridges (including railway bridges, pedestrian bridges, piers, etc.) (hereinafter referred to as “elevated roads”). Further, the present invention relates to a composite girder floor slab replacement method and a main girder provisional structure in the composite girder floor slab replacement method.

  Elevated road floor slabs may be depressed or damaged due to aging or accidents, and these floor slabs need to be replaced. FIG. 10 shows an example of an elevated road. This elevated road is a composite girder. A composite girder is a structure in which various types of floor slabs such as steel slabs, concrete slabs, and synthetic slabs are integrally mounted on a steel main girder, and the floor slab is part of the main girder. The floor slab is integrated, and it is difficult to remove the floor slab separately from the main girder. Therefore, when replacing the floor slab, the upper part of the web of the main girder is cut to remove the floor slab, the upper flange, and the cut upper end of the web (hereinafter collectively referred to as the “replacement part”) ( There exists patent document 1).

  In the replacement of composite slab floor slabs, noise is generated by cutting floor slabs, removing replacement parts, etc., so the longer the construction period, the greater the impact on the surrounding environment. In addition, the number of times of regulation and the time of regulation increase, so the impact on traffic increases, and the costs (regulation costs) associated with traffic regulation increase. In the case of toll roads, the toll is reduced.

  In the replacement work, after the replacement part is removed, the traffic may be partially opened (one-way traffic). However, since the main girder from which the replacement part has been removed cannot receive the load of the passing vehicle or the dead load depending on the case, conventionally, the main girder is temporarily received (reinforced) with an external cable as shown in FIG. Or by provisionally receiving the main girder with a vent as shown in FIG.

JP 2007-239365 A

The method of temporarily receiving the main girder with the outer cable (FIG. 11A) has the following difficulties.
(1) The reinforcement of the fixing portion is increased.
(2) A compressive force is introduced into the main girder, which adversely affects the construction when cutting the slab.
(3) Since the composite girder is easy to bend when the upper flange is removed together with the floor slab, it is difficult to adjust the camber. Here, the camber refers to an amount that is produced by calculating the deflection due to the dead load in consideration of the girder being a straight line when completed, and increasing the girder by the dead load in advance.
(4) The steel main girder supporting the elevated road may be bent in a plane when the road surface is a curve in a plane. When reinforcing the curved main girder using an outer cable, if an axial force is introduced into the main girder, the main girder is undesirably affected by eccentric bending.

  The method of temporarily receiving the main girder at the vent (FIG. 11 (b)) is unlikely to cause the above-mentioned difficulties, but in urban areas, a large street is located under the elevated road in parallel for the purpose of advanced use of land. There are many places, and it is not uncommon for a vent to serve as a temporary support.

  The problem to be solved by the present invention is that it is possible to construct safely and reliably without using a vent, to shorten the construction period, to be able to handle curved girders, to easily adjust camber, and to improve the economical efficiency of floor slabs for synthetic girders. The main girder provision method in the replacement method, the floor slab replacement method for the composite girder, and the main girder provision structure in the floor slab replacement method for the composite girder.

[Primary girder provision method in composite girder replacement method]
The main girder provision method (hereinafter simply referred to as “main girder provision method”) in the floor replacement method of the composite girder of the present invention is a part of the main girder of the composite girder (hereinafter referred to as “existing main girder”). A part of the floor slab above (hereinafter referred to as “existing floor slab”) is cut, and the cut existing main girder (hereinafter referred to as “removed main girder”) and the cut existing floor slab (hereinafter referred to as “replacement floor”). In the floor slab replacement method, the main girder (hereinafter referred to as “new main girder”) and the newly installed floor slab (hereinafter referred to as “new floor slab”) are removed from the existing main girder. In this method, the existing main girder is provisionally received before the cutting. In this main girder provisional method, a reaction force frame is installed below the existing main beam, a support beam is arranged below the reaction force frame, the existing main beam and the support beam are joined, and the support beam and the existing main beam are placed between them. This is a method of temporarily receiving an existing main girder by arranging a jack and jacking up. The reason for jacking up the existing main girder is to remove the influence of these existing loads on the existing floor slab, in addition to post-dead loads such as pavement and sound insulation walls, as well as the scaffolding and support girder loads for construction. Because. Another reason is that an effect of reducing the reinforcing structure of the existing main girder can be brought about by bearing the amount of positive bending of the existing main girder to some extent by the supporting girder.

  In the main girder provisional method, a supporting girder is joined to two or more existing main girder arranged at intervals, and a horizontal girder is installed between adjacent supporting girder of the supporting girder to reinforce the supporting girder. You can also.

[Synthetic girder slab replacement method]
The composite girder floor slab replacement method of the present invention (hereinafter simply referred to as “floor slab replacement method”) is to remove a part of the existing main girder of the composite girder and a part of the existing floor slab above it. In the floor slab replacement method of installing a new main girder and a new floor slab on the removal trace, after temporarily receiving the existing main girder by the main girder provisional receiving method, horizontally cutting the replacement part of the existing main girder, This is a method of cutting the replacement part of the existing floor slab, removing them (removed main girder and replacement floor slab), and installing the new main girder and the new floor slab on those removed sites.

  In the floor slab replacement method, two or more new floor slabs are installed and fixed in the direction of the bridge axis, and the existing main girder and the new main girder are bent upward by jacking up and bent, thereby It is also possible to introduce a compressive force to the newly installed floor slab and the interlining material by opening a gap in the joint portion, filling the interspace material with the intercalating material and then jacking down. The jack-up in this case can be performed with a longer jack-up stroke than the jack-up when the existing main girder is provisionally received by the support girder.

  In the floor slab replacement method, the replacement location of the existing main girder is horizontally cut, and if necessary, an additional plate is attached to the cutting location to temporarily reinforce the cutting location, and the existing main girder and the existing floor Removal of the cut portion of the plate can be performed after removing the attachment plate.

[Main girder provision structure in composite girder replacement method]
In the composite girder floor slab replacement method of the present invention, the main girder provision structure (hereinafter simply referred to as “main girder provision structure”) is a part of the existing main girder of the composite girder and one of the existing floor slabs on it. This is a main girder provisional structure in the floor slab replacement method in which a new main girder and a new floor slab are installed on the removal trace, and a reaction force stand is installed under the existing main girder. A support girder is placed under, the existing main girder and the support girder are joined by the joining means, and a jack is placed between the support girder and the existing main girder to jack up the existing main girder. is there.

In the main girder provisional structure, a bracket is fixed to a web of an existing main girder, and a PC steel rod or PC steel is provided between the bracket and the lower flange of the support girder without making a hole in the lower flange of the existing main girder. A structure in which a stranded wire (hereinafter referred to as “PC steel”) is installed, and the existing main girder is temporarily received by tightening the PC steel and joining the reaction frame and the support girder.

  The main girder provisional structure is formed by joining support girders to two or more existing main girders arranged with a space between them, and in order to reduce the influence of lateral buckling, between adjacent support girders. A structure in which a horizontal beam is erected and the support beam is reinforced may be used.

The main girder provisional method, floor slab replacement method, and main girder provisional structure of the present invention have the following effects.
(1) Compared to the outer cable method, the rigidity is increased and vibration is reduced, so that it is preferable for a traveling vehicle and the surrounding environment, and construction can be performed safely and reliably.
(2) Since the support girder is joined to the existing main girder and the existing main girder is temporarily received, it is possible to work without problems even in a place where the vent cannot be raised.
(3) If axial force is introduced into the existing main girder, it will be difficult to cut, and reinforcement may be required for the existing main girder. However, since axial force is not introduced into the existing main girder, it will not be difficult to cut. There is no need to reinforce the existing main girder.
(4) Since no axial force is introduced into the existing main girder, it is suitable for provisional reception of a main girder that is curved in a plane.
(5) Since the reaction force management can be performed relatively easily by providing the jack, the camber adjustment can also be performed relatively easily.
(6) It is economical because the support girder can be used over and over again.
(7) When jacking up and filling the joints of the newly installed floor slab with a filling material, and jacking down and introducing compressive force into the new floor slab and the filling material, the compressing force is applied to the padding part that tends to be a weak point. Since it is introduced, the infiltration of water from the road surface is prevented and the durability of the floor slab is improved.
(8) If the supporting girders are made of FRP or aluminum, the temporary support structure is reduced in weight.
(9) If the lower flange of the bracket and support girder is wider than at least the lower flange of the main girder and the upper and lower flanges of the reaction force frame, the bracket Since the lower flange of the support girder can be tightly connected with the PC steel material, there is no disadvantageous situation such as an increase in stress due to the effect of drilling in the lower flange as in the case where a hole is made in the lower flange of the support girder. As for the horizontal force against the support girders, the steel members constituting the main girders, reaction force mounts or support girders due to the tension of PC steel, or the steel members constituting the support girders should be temporarily clamped together with a vise. It can respond.
(10) By jacking up the existing main girder from the support girder, a tensile force can be applied without introducing a compressive force to the floor slab, so that the cutter blade becomes difficult to bite and easily cut when the floor slab is cut. This improves the workability.
(11) By jacking up the existing main girder from the support girder, the amount of positive bending of the existing main girder can be borne by the support girder to some extent, and this also has the effect of reducing the reinforcement structure of the existing main girder. it can.

1 shows an example of a main girder provisional method and a main girder provisional structure according to the present invention, in which (a) is a side view showing a state in which a reaction force frame is installed on an existing main girder, and (b) is a diagram showing a supporting girder. Side view showing the state of placing under the girder (reaction force stand), (c) is a jack installed between the joined support girder and the existing main girder, and jacking up the jack to temporarily receive the existing main girder The side view which shows the state which carried out. 1 shows an example of a main girder provisional method and main girder provisional structure according to the present invention, in which (a) is a front view of FIG. 1 (a), (b) is a front view of FIG. 1 (b), and (c). Is a front view of FIG. It shows an example of a method of installing the support girder below the existing main girder. (A) is a side view showing a state in which a scaffold protector is installed on a scaffold chain suspended from the existing main girder. (B) is a scaffold. Side view showing the state where the roller conveyor is installed in the protective work, (c) is a side view showing the state where the trolley rail is fixed to the existing main girder, and (d) is the state where the trolley and chain block are attached to the trolley rail. (E) is a side view showing a state in which the support beam is sequentially slid and moved by the trolley and the chain block, and (f) is a side view showing a state in which the support beam is assembled by repeating the operation of (e). 1 shows an example of a floor slab replacement method according to the present invention. FIG. 2A shows a method for temporarily installing an existing main girder according to the main girder temporary receiving method of the present invention, and then installing a reinforcing member, horizontally cutting the existing main girder, Side view showing the state of temporary attachment of the contact plate, (b) shows the state of cutting and removing the existing floor slab, installing the new main girder and the new floor slab, and temporarily paving the new floor slab Side view, (c) is a side view showing a state in which the support girder has been removed and the newly installed floor slab has been paved. It shows an example of the floor slab replacement method of the present invention, (a) is a front view of FIG. 4 (a), (b) is a front view of FIG. 4 (b), (c) is FIG. 4 (c). Front view. The other example of the floor slab replacement method of the present invention is shown, (a) is an explanatory view showing a state where the stroke of the jack is extended and the joint portion of two or more newly installed floor slabs is filled with a filling material, b) Explanatory drawing which shows the state jacked down after filling with a filling material. An example of the main girder provisional receiving structure of the present invention is shown. (A) is a side view showing a structure in which a jack installed between a joined support girder and an existing main girder is jacked up and the existing main girder is provisionally received. , (B) is a front view of (a). An example of a joining means is shown, Comprising: (a) is a side view which shows an example in the case of joining using PC steel materials, (b) is AA sectional drawing of (a). The other example of a joining means is shown, Comprising: (a) is a side view which shows an example in the case of joining using a high strength volt | bolt, (b) is BB sectional drawing of (a). The perspective view which shows an example of an elevated road. It shows an example of a conventional floor slab replacement method, where (a) is a side view when an existing main girder is supported by an external cable and a composite floor slab is replaced, and (b) is an existing main using a vent. The side view in the case of replacing an existing floor slab while supporting a girder.

(Embodiment of temporary girder acceptance method)
An example of the main girder provisional receiving method of the present invention will be described with reference to the drawings. The main girder provisional method of the present invention is a method that can be used for replacement of a composite girder floor slab. Here, a case will be described as an example where the elevated road is a highway with two lanes on one side, one lane of the two lanes is opened, and traffic is regulated in the other lanes.

[Outline of the provisional key digit acceptance method]
1 (a) to 1 (c) and FIGS. 2 (a) to 2 (c), the main girder provisional receiving method is such that the reaction force stand 2 is placed below each of the existing main girders 1 arranged at intervals. The supporting girder 3 is disposed below the reaction force frame 2, the supporting girder 3 is joined to the existing main girder 1 by the joining means 4, and the jack 5 is interposed between the supporting girder 3 and the existing main girder 1. In this method, the existing main girder 1 is provisionally received by jacking up the jack 5.

[Installation of reaction stand]
The reaction force base 2 below the existing main girder 1 is suspended from a crane or a chain block (not shown) from above the existing main girder 1 and pulled up below the lower flange 1b of the existing main girder 1. It fixes to the lower flange 1b of the existing main girder 1. In this embodiment, H-shaped steel is used as the reaction force frame 2 (FIGS. 2A to 2C), and the upper surface of the upper flange 2 a of the reaction force frame 2 is the lower surface of the lower flange 1 b of the existing main beam 1. It is arranged and fixed so as to face to. Two or more reaction force stands 2 are installed at intervals in the longitudinal direction of the existing main girder 1. The number of installed reaction force stands 2 and the installation interval can be appropriately set according to the length of the existing main girder 1 and the length of the support girder 3. Moreover, the lower flange 1b and the upper flange 2a may be fastened with a vise or the like as a method for fixing the reaction force frame and the existing main girder 1.

[Arrangement of support girders]
A support girder 3 is arranged under the reaction force stand 2. The arrangement method of the support girder 3 depends on the length of the support girder 3, but when a long support girder 3 is required, several support girder parts (hereinafter referred to as “support beams”) 3x are placed under the expressway. After assembling, it can be hung under the reaction force frame 2 or several support beams 3x can be hung under the reaction force frame 2 and then assembled. In the former case, the assembled support beam 3 can be placed on a multi-axis carriage (not shown), conveyed to an installation location, and lifted from the existing main beam 1. In the case of the latter, it can carry out like Fig.3 (a)-(f), for example.
(1) As shown in FIG. 3A, the scaffold chain 7 is suspended from the existing main girder 1, and the scaffold protector 8 is installed on the lower end side of the scaffold chain 7. A plurality of scaffold chains 7 are installed at intervals in the longitudinal direction of the existing main girder 1.
(2) As shown in FIG. 3B, transport means such as a roller conveyor 6 is installed on the scaffolding protector 8.
(3) As shown in FIG. 3 (c), the trolley rail 9 is placed on the roller conveyor 6 and transported to the longitudinal direction of the conveyor 6, and the trolley rail 9 is placed under the existing main girder 1. Fix to the flange 1b.
(4) As shown in FIG.3 (d), the trolley 10 and the chain block 11 are attached to the rail 9 for trolleys.
(5) As shown in FIG. 3 (e), the support beam 3 x is transported below the trolley 10 and the chain block 11, and the support beam 3 x is attached to the chain block 11. The support beams 3x attached to the chain block 11 are slid in the longitudinal direction of the existing main beam 1 and assembled sequentially.
(6) The operations (4) and (5) are repeated as many times as necessary to complete the assembly of the support beam 3.

  Here, although the case where the roller conveyor 6 is used as an example of transportation is taken as an example, the transportation means may be other than this. Although the description of the steps (1) to (6) is omitted, the trolley 10 and the chain block 11 are removed after the sliding movement of all the support beams 3x is completed, and one of the trolley rails 9 is removed. The part can be removed after the support beam 3 is joined to the existing main beam 1 by the joining means 4. A jack 5 for temporarily receiving the existing main girder 1 can be disposed in a portion where the trolley rail 9 has been removed (FIG. 7A).

[Join of support girders]
The support beam 3 assembled by the above method is bonded to the existing main beam 1 by the bonding means 4. Specifically, the assembled support girder 3 is lifted until its upper flange 3a abuts against the lower flange 2b of the reaction force frame 2, and the upper flange 3a of the support beam 3 and the lower flange 2b of the reaction force frame 2 The support girder 3 is joined to the existing main girder 1 with the upper flange 2a of the reaction force frame 2 and the lower flange 1b of the existing main girder 1 in contact with each other. As the joining means 4 of the supporting girder 3 to the existing main girder 1, there is a means of using PC steel or high strength bolts. These joining means 4 will be described later. Although not shown, it is desirable to attach the lifting chain block to the existing main beam 1 and to support the supporting beam 3 with the lifting chain block when the support beam 3 is joined. The lifting chain block can be removed after the support beam 3 is joined to the existing main beam 1. The stress transmission structure of the existing main girder 1 and the reaction force frame 2 and the support girder 3 and the reaction force frame 2 may be a rigid structure or a hinge structure. In the case of the hinge structure, the reaction force mount 2 is not bent, and the structure is simplified. On the other hand, if it becomes a rigid connection structure, although the bending will also act on the reaction force stand 2, the maximum bending of the support beam 3 will be relieved.

[Jack installation and provisional acceptance of main girder by jack]
A jack 5 is arranged between the existing main girder 1 and the supporting girder 3 joined below it, the jack 5 is jacked up, and the load applied to the existing main girder 1 is temporarily received by the jack 5, and the supporting girder 3 to transmit the load.

(Embodiment 1 of slab replacement method)
An example of the floor slab replacement method of the present invention will be described with reference to the drawings. This embodiment is an example in which the elevated road is a highway with two lanes on one side, where one lane of the two lanes is opened for traffic and the other lanes are traffic regulated to replace the floor slab.

[Overview of floor slab replacement method]
The floor slab replacement method of this embodiment temporarily receives the existing main girder 1 by the main girder provisional method of the present invention described above, and thereafter, FIGS. 4 (a) to (c) and FIGS. 5 (a) to (c). ), The web 1c of the existing main girder 1 is cut horizontally, the replacement floor slab 21a of the existing floor slab 21 is cut, the removed main girder 1x and the replacement floor slab 21a are removed, This is a construction method in which a new main girder 26 and a new floor slab 22 are installed and temporarily paved in the removal trace space, and then the support girder 3 and the reaction force frame 2 are removed and the floor slab 21 is replaced by main paving. The existing floor slab 21 is cut into a size that is easy to remove.

[Installation of reinforcing members, horizontal cutting of existing main girders, temporary attachment]
When the existing main girder 1 is cut horizontally, a reinforcing member 20 (FIG. 4 (a)) that functions as an upper flange after cutting the main girder in the vicinity of the cut portion of the web 1c of the existing main girder 1 before cutting. After the installation and cutting, the attachment plate 23 (FIG. 4A) may be temporarily attached to the cut portion (for example, a broken line portion in FIG. 8A or FIG. 9A, the same applies hereinafter) C. An existing steel plate can be used for the reinforcing member 20. The reinforcing member 20 can be fixed to the existing main girder 1 by fixing means such as bolts and nuts (not shown). An existing steel plate can also be used for the attachment plate 23, and it can be temporarily fixed to the existing main girder 1 with a temporary fastening bolt (not shown) such as a hexagonal high strength bolt. The existing main girder 1 can be cut by, for example, a gas cutter.

[Removal of existing floor slabs, installation of new floor slabs, temporary paving]
The removed main girder 1x and the existing replacement floor slab 21a are lifted and removed by the crane S (FIG. 4B). After the replacement floor slab 21a is removed, a new floor slab 22 is installed and temporarily paved. When the main girder web 1c is cut up and down in advance and the attachment plate 23 is temporarily attached, the attachment plate 23 is removed, and then the removed main girder 1x and the replacement floor slab 21a are removed. In some cases, the main pavement may be performed on the upper surface of the new floor slab 22 in advance. In this case, paving is performed at the factory, which can contribute to rapid construction.

[Removal of support girders and reaction force mounts, paving]
The new floor slab 22 is installed and temporarily paved, and then the support beam 3 and the reaction force stand 2 are removed. The removal of the support girder 3 and the reaction force gantry 2 can be performed in the reverse process to the installation of the support girder 3 and the reaction force gantry 2. When the support girder 3 is assembled and lifted under the highway, the support girder 3 in the assembled state is hung with a crane S or a chain block (not shown) and placed on a multi-axis carriage for removal. When the support beams 3x are sequentially lifted and then assembled, the support beams 3x are prepared and disassembled, the disassembled support beams 3x are suspended by a crane S or a chain block (not shown), and the transport vehicle T (FIG. 3 (e) ( f)) to remove. After the support beam 3 is removed, the reaction force frame 2 is removed and the main pavement is performed.

(Embodiment 2 of slab replacement method)
Another example of the floor slab replacement method of the present invention will be described with reference to the drawings. The basic procedure of the floor slab replacement method of this embodiment is the same as that of the first embodiment. The difference is that, as shown in FIGS. 6A and 6B, a large number of new floor slabs (for example, precast floor slabs) 22 are arranged on the existing main girder 1, and then the existing main girder 1 and the supporting girder 3 are arranged. The existing main girder 1 and the new main girder 26 are bent upward, a gap is formed in the joint portion 24 of the adjacent new floor slab 22, and the gap between concrete, mortar, etc. This is a point of introducing a compressive force to the interlining material 25 and the newly installed floor slab 22 by jacking down the jack 5 after the filling material 25 is filled. This makes it difficult for water to enter from the road surface, leading to improved durability of the floor slab.

(Embodiment of main girder provisional structure)
An example of the main girder provisional receiving structure of the present invention will be described with reference to the drawings. This main girder provisional structure is a structure in the middle of replacing the floor slab of the composite girder. Here, a case will be described as an example in which the elevated road is a highway with two lanes on one side, one lane in the two lanes is opened, and the work is performed in a state where traffic is restricted in the other lanes.

[Overview of main girder provisional structure]
As shown in FIGS. 7A and 7B, the main girder provisional structure of this embodiment is provided with a reaction force stand 2 below the existing main girder 1, and a support girder 3 below the reaction force stand 2. Is arranged, and the supporting girder 3 is joined to the existing main girder 1 by the joining means 4, the jack 5 is arranged between the supporting girder 3 and the existing main girder 1, and the existing main girder 1 is Temporarily received structure.

[Reaction force stand]
The reaction force stand 2 is disposed and fixed below the lower flange 1b of the existing main girder 1. For example, an H-section steel provided with an upper flange 2a, a lower flange 2b, and a web 2c can be used as the reaction force frame 2. Moreover, you may provide the rib which connects between the upper flange 2a and the lower flange 2b in a perpendicular direction as needed. The width of the upper flange 2a and the lower flange 2b of the reaction force frame 2 is the same (substantially the same) as the width of the lower flange 1b of the existing main girder 1. Two or more reaction force stands 2 are installed at intervals in the longitudinal direction of the existing main girder 1 (FIG. 7A). The number of installed reaction force stands 2 and the installation interval can be appropriately set according to the length of the existing main beam 1 and the length of the support beam 3. The reaction force stand 2 is installed under each of a plurality of existing main girders 1 arranged at intervals (FIG. 2A). There are various methods for attaching the reaction force stand 2 to the existing main girder 1. For example, it can be temporarily fixed with other fastening tools such as Bullman (registered trademark) made by Bullman Co., Ltd., or a high strength bolt. Or can be fixed by welding or the like.

[Supporting girder]
The support girder 3 has a strength capable of temporarily receiving the existing main girder 1 and can be made of steel, aluminum, FRP, or the like. If the existing main girder 1 is made of aluminum or FRP, the weight can be reduced. The length of the support beam 3 can be sufficiently handled by about 80% of the length of the existing main beam 1 (main beam length). For example, if the existing main beam 1 is 30 m, about 24 m is sufficient for the support beam 3. is there. As an example, the support girder 3 shown in FIGS. 8A and 8B is an I-shaped steel, and the width of the lower flange 3b is the width of the upper flange 3a (the lower flange 1b of the existing main girder 1 at a place where the reaction force mount 2 is located. It is wide enough that it does not interfere with the PC steel material arranged vertically. An arbitrary flange width can be taken in a place where the reaction force mount 2 is not provided because it does not interfere with the PC steel material.

  Support girder ribs 12 (FIG. 8A) are provided at locations near the ends of the support girder 3 in the longitudinal direction (axial direction). As an example, the support girder rib 12 shown in FIG. 8A has a rectangular shape spreading toward the hem side when viewed from the front, and is disposed between the upper flange 3a and the lower flange 3b of the support girder 3. The support girder ribs 12 are arranged on both sides of the support girder 3 with the web 3c interposed therebetween. The support girder may be other than the I-shaped steel, and for example, a box cross-section or a truss type can be used. The supporting girders 3 are installed under each of a plurality of existing main girders 1 arranged at intervals, and these supporting girders 3 are horizontal girders 13 (FIG. 7B). Joined and reinforced.

[Joint means]
The support girder 3 disposed below the existing main girder 1 is joined to the existing main girder 1 by the joining means 4. There are various means in the joining means 4, and main examples include a means using a PC steel material 14 and a means using a high strength bolt 15. FIGS. 8A and 8B show the joining structure when the PC steel material 14 is used, and FIGS. 9A and 9B show the joining structure when the high-strength bolt 15 is used.

[Joint structure when using PC steel]
When the PC steel material 14 is used (FIGS. 8A and 8B), the brackets 16 are attached to both surfaces of the web 1c (FIG. 8A) of the existing main girder 1 by welding, high-strength bolts, or the like. When using a high strength bolt, a hole is made in the web 1c, and the high strength bolt is inserted into the hole and connected. In either case of welding or high-strength bolts, the bracket 16 is attached so as to protrude to the outside (side) of the web 1c. A main girder rib 17 is disposed vertically between the bracket 16 and the lower flange 1b of the existing main girder 1 or parallel to the PC steel material 14. This fixing can be performed by welding, bolting or the like. The bracket 16 is attached below the cut portion C of the web 1c so that it remains in the existing main beam 1 even if the removed main beam 1x is removed.

  As shown in FIG. 8B, the horizontal width of the bracket 16 is determined by the horizontal width of the upper and lower flanges 1 a and 1 b of the existing main girder 1, the horizontal width of the upper and lower flanges 2 a and 2 b of the reaction force frame 2, and the upper flange of the support girder 3. It is made wider than the lateral width of 3a, and both end portions in the lateral direction of the bracket 16 are projected to the sides of the flanges 1a, 1b, 2a, 2b, 3a. By using a wide I-shaped steel so that the horizontal width of the bracket 16 is wide and the horizontal width of the lower flange 3b does not interfere with the PC steel material 14 disposed vertically compared to the horizontal width of the upper flange 3a. Since both sides of the width direction and the lower flange 3b of the support girder 3 protrude to the side of the lower flange 1b of the existing main girder 1 and the upper flange 3a of the support girder 3, no holes are formed in the lower flange 1b and the upper flange 3a. In both cases, the PC steel material 14 can be passed through the lower flange 1b of the existing main girder 1 and the upper flange 3a of the support girder 3 and through a through hole (not shown) provided in the lower flange 3b of the bracket 16 and the support girder 3. it can. A tension nut 19 is provided on each of the upper projecting portion 14a projecting above the bracket 16 and the lower projecting portion 14b projecting below the lower flange 3b of the support beam 3 via the bearing plate 18 in the PC steel material 14. By tightening, the existing main girder 1 and the support girder 3 are tensioned and connected. In this case, since it is not necessary to make a hole in the lower flange 1b of the existing main girder 1 or the upper flange 3a of the support girder 3, the stress considering the effect of drilling in the lower flange as in the case of making a hole. There will be no increase.

[Joint structure when using high-strength bolts]
When a high strength bolt is used as the joining means 4, as shown in FIGS. 9A and 9B, the lower flange 1 b of the existing main girder 1 and the upper flange 2 a of the reaction force base 2 are fixed with the high strength bolt 15, The upper flange 3 a of the support beam 3 and the lower flange 2 b of the reaction force base 2 are fixed with high-strength bolts 15. The existing main girder 1 is provided with a main girder rib 17 having a substantially rectangular shape when viewed from the front, and the support girder 3 is provided with support girder ribs 12 on both sides of the web 3c. A through-hole (not shown) is made in the lower flange 1b of the existing main girder 1, the upper and lower flanges 2a, 2b of the reaction force frame 2, and the upper flange 3a of the support girder 3 so that the high-strength bolt 15 can be inserted. .

[jack]
Various hydraulic jacks can be used for the jack 5 disposed between the support beam 3 and the existing main beam 1. The jack 5 may be an existing one or a new one. A plurality of jacks 5 are installed for each existing main girder 1 (FIG. 7A). The number and location of jacks 5 can be appropriately selected according to the length, size, shape, load, etc. of the existing main girder 1 to be supported.

  The above-described embodiment is a case where the elevated road is a highway with two lanes on one side, where one lane of the two lanes is opened to traffic, the other is traffic-regulated, and the traffic slab floor slab In this case, the floor slab can be replaced by alternately switching between a lane that opens traffic and a lane that restricts traffic. In the case of three lanes on one side, some lanes can be opened and other lanes can be traffic regulated.

  The main girder provisional method, floor slab replacement method, and main girder provisional structure of the present invention can be used for exchanging floor slabs that are similar to those other than elevated roads.

1 Existing main girder 1a Upper flange (for existing main girder) 1b Lower flange (for existing main girder) 1c Web (for existing main girder) 1x Removed main girder 2 Reaction force stand 2a (Reaction force stand) upper flange 2b (Reverse force) Lower flange 2c (for reaction rack) Web 3 Support beam 3a Upper flange 3b (Support beam) Lower flange 3c (Support beam) Web 3x Support beam 4 Joining means 5 Jack 6 Roller Conveyor 7 Scaffolding chain 8 Scaffolding protector 9 Trolley rail 10 Trolley 11 Chain block 12 Supporting girder rib 13 Horizontal girder 14 PC steel 14a Upper projecting part 14b Lower projecting part 15 High strength bolt 16 Bracket 17 Main girder rib 18 Bearing plate 19 Tension Nut 20 Reinforcing member 21 Existing floor slab 21a Replacement floor slab 22 New floor slab 23 Joint plate 24 Joint part 25 Filling material 26 Newly installed Main girder C Cutting point S Crane T Transportation vehicle

Claims (6)

In the main girder provisional method in the composite girder floor slab replacement method, which temporarily provisions the existing main girder when replacing the existing girder of the composite girder,
Install a reaction force stand below the existing main girder,
A support girder is arranged below the reaction force mount,
Joining the supporting girders to the existing main girders by means of joining,
Placing a jack between the joined support beam and the existing main beam,
Temporarily receiving the existing main girder by jacking up the jack,
The main girder provisional method in the composite girder floor slab replacement method. In the main girder provisional receiving method in the floor slab replacement method of the composite girder according to claim 1,
Join the supporting girders to two or more existing main girders arranged at intervals,
Reinforcing the support beam by installing a horizontal beam between adjacent support beams among the support beams,
The main girder provisional method in the composite girder floor slab replacement method. In the composite girder floor slab replacement method that cuts and removes part of the existing main girder of the composite girder and part of the existing floor slab above it, and installs the new main girder and the new floor slab on the removal trace,
After provisionally accepting the existing main girder by the main girder provisional method according to claim 1 or claim 2, the replacement part of the existing main girder is cut horizontally, and the replacement part of the existing floor slab is cut, Remove the cut existing main girder and the cut existing floor slab, and install the new main girder and the new floor slab on the removal site,
Synthetic girder floor slab replacement method. In the composite girder floor slab replacement method according to claim 3,
Two or more new floor slabs are installed and fixed in the direction of the bridge axis, and the existing main girder and the new main girder are bent upward by jacking up so that a gap is created in the joint portion of the two or more new floor slabs. After filling the gap with the filling material, jack down to introduce compressive force into the new floor slab and the filling material,
Synthetic girder floor slab replacement method. Cut off part of the existing main girder of the composite girder and part of the existing floor slab above it, and install the new main girder and the new floor slab on the removal trace. In the receiving structure,
A reaction force stand is installed below the existing main girder, a support girder is placed below the reaction force stand, the existing main girder and the support girder are joined by a joining means, and a jack is arranged between the support girder and the existing main girder. The existing main girder was provisionally received by jacking up,
A main girder provisional structure in the floor slab replacement method for composite girder characterized in that. In the main girder provisional structure in the floor slab replacement method of the composite girder according to claim 5,
A bracket is fixed to the web of the existing main girder,
Without making a hole in the lower flange of the existing main girder, a PC steel material is installed between the bracket and the lower flange of the support girder ,
The existing main girder was provisionally received by tightening the PC steel material and joining the reaction force frame and the support girder,
A main girder provisional structure in the floor slab replacement method for composite girder characterized in that.

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