JP7242821B1 - Concrete balustrade construction method - Google Patents

Abstract

An object of the present invention is to shorten the work time required for constructing a concrete wall balustrade of a bridge superstructure. In this concrete wall balustrade construction method, a bottom frame for a concrete floor slab is placed, a concrete precast wall balustrade member is temporarily placed at the tip of the concrete floor slab, and placed inside the formwork. This is done by assembling reinforcing bars for concrete floor slabs and pouring concrete for the concrete floor slabs. [Selection drawing] Fig. 7

Description

TECHNICAL FIELD The present invention relates to a method for constructing a concrete protection wall (wall balustrade) for a bridge superstructure.

There is a construction to replace the existing steel bridge protection fence with a concrete bridge protection wall (concrete wall balustrade) as a renewal work of the bridge protection fence of the existing bridge with the overhang floor slab. Since there is a large difference in weight between the steel bridge guard fence and the concrete wall balustrade, when a new concrete wall balustrade is constructed, the strength of the base of the existing overhanging floor slab may be insufficient. If it is difficult to externally reinforce this lack of strength, the overhanging floor slabs are also renewed at the same time.

Construction of a concrete wall balustrade that accompanies such renewal of the overhanging floor slabs involves cutting the overhanging slabs at their roots, reconstructing new overhanging slabs that satisfy the required bearing strength with cast-in-place concrete, and constructing the overhanging floors. This is done by constructing a new concrete balustrade on the tip of the plate. Here, the overhanging floor slab and the wall balustrade generally have different concrete mixes, so the overhanging floor slab and the wall balustrade are generally constructed separately. In this case, for example, rebars that connect to the balustrade are protruded from the top surface of the overhanging floor slab, and after the construction of the overhanging slab is completed, the reinforcing bars of the wall balustrade are assembled by connecting to the protruding rebars, and the formwork is installed. Install and pour concrete to construct the wall balustrade. However, this procedure requires two separate constructions of the cast-in-place concrete structure, which increases the time required for the operation. For this reason, it is desirable to improve construction methods for overhanging floor slabs and wall balustrades at sites where a shortened construction process and early release of traffic restrictions are desired.

In recent years, with the aim of shortening the construction period and traffic control time, after removing the existing floorboards, a method of laying precast floorboards with a width of about 2m in the direction of the bridge axis manufactured at the factory has been adopted. . Wall balustrades are generally constructed after laying precast floor slabs, but even when constructing wall balustrades, there is a method of constructing precast wall balustrades made at the factory on precast slabs for the purpose of shortening the construction period. Adopted. According to this method, there is no need to spend time on concrete placement and curing, so it is possible to shorten the overall construction period or shorten the traffic control time.

However, regarding the connection between the precast floor slab and the precast wall balustrade, for example, anchor rebars are installed in the precast floor slab in a protruding state, and anchor holes for inserting the anchor rebars are installed in the precast wall balustrade. There is known a method of inserting anchor reinforcing bars that protrude from the floor slab and filling the mutual gaps with, for example, mortar for integration (for example, Cited Document 1).

There is also a method of embedding anchor bolts in precast floor slabs instead of anchor reinforcing bars, inserting the anchor bolts into anchor holes provided in precast wall balustrades, and fixing them with nuts (for example, Cited Document 2).

In addition, regarding the construction to renew only the wall balustrade, after removing the existing wall balustrade, the reinforcing bars on the existing overhanging floor slabs were ground, and the reinforcing bars that connect to the floor slabs were protruding from the lower ends that had been manufactured in advance at the factory, etc. There is a known method of constructing a wall balustrade by installing a precast balustrade with a gap between the upper surface of the overhanging floor slab and the lower end of the precast balustrade, and filling the gap with non-shrinking mortar (for example, Reference 3).

In addition, there is renewal work of bridge protection fences on overhanging slabs of concrete precast bridge girders and floor slab bridges constructed with cast-in-place concrete. In this renewal work, when replacing steel protective fences with concrete wall balustrades, the weight difference between steel protective fences and concrete wall balustrades is large, and there may be cases where the bearing capacity at the base of the overhanging floor slabs is insufficient. Therefore, the overhanging slab may be renewed along with the bridge protection fence on the overhanging slab. Since the overhanging slab is generally a concrete structure, the overhanging slab is cut and removed at the boundary between the precast bridge girder and the slab bridge body, and a new overhanging slab is constructed using cast-in-place concrete. At that time, since the existing wall balustrade will be removed together with the existing overhanging floor slab, it will be necessary to construct a new wall balustrade. The new wall balustrade is constructed by connecting the reinforcing bars of the new wall balustrade to the reinforcing bars protruding from the new overhanging floor slabs, assembling the reinforcing bars, and constructing the cast-in-place concrete.

JP 2017-115485 A JP-A-09-29641 JP 2013-36205 A

In order to shorten the construction period, the concrete floor slabs laid on the steel bridge were renewed by laying new precast floor slabs manufactured at the factory and then installing precast wall balustrades manufactured at the factory and connecting them to the precast floor slabs. often
However, since precast members are connected to each other, it is necessary to install anchor reinforcing bars and anchor bolts on precast floor slabs and anchors on precast wall balustrades.

In the renewal work of only the wall balustrade, the existing wall balustrade will be cut and removed, and the existing overhanging floor slab will be reused as it is. A method is adopted in which connecting reinforcing bars are protruded, a gap is opened between the upper surface of the overhanging floor slab and the lower end of the precast wall balustrade, a precast wall balustrade is installed, and the gap is filled with non-shrinkage mortar.

However, in order to connect the reinforcing bars between the overhanging floor slab and the precast wall balustrade, the connection between the overhanging floor slab and the precast wall balustrade is complicated, such as the use of special reinforcing bar joints and the construction of post-installed anchors on the upper surface of the overhanging floor slab. be. In addition, in order to fill the gap between the overhanging floor slab and the precast wall balustrade with non-shrink mortar, it is necessary to install forms on the road side and outside of the precast wall balustrade.
Furthermore, when updating precast concrete bridge girders and overhanging deck slabs of concrete slab bridges, it is common to manufacture newly constructed overhanging slabs and overhanging balustrades with cast-in-place concrete. Concrete placement and curing require time, and work hours are severely restricted in renewal work subject to traffic restrictions.

In view of the above circumstances, it is an object of the present invention to provide a concrete wall balustrade construction method capable of shortening the work time required to construct a concrete balustrade of a bridge superstructure.

In order to achieve the above object, a method for constructing a concrete wall balustrade according to the present invention comprises placing a bottom frame for a concrete floor slab, and placing precast concrete wall balustrade members on the concrete floor slab bottom frame. This is done by temporarily placing the concrete floor slab at the tip, assembling reinforcing bars for the concrete floor slab in the formwork, and pouring the concrete for the concrete floor slab.

The precast wall balustrade member may have a fixing member to the concrete floor slab protrude so that the precast wall balustrade member is fixed to the concrete of the concrete floor slab cast in the mold.

ADVANTAGE OF THE INVENTION According to this invention, the work time of wall balustrade renewal construction can be reduced by changing the wall balustrade constructed with the cast-in-place concrete to the precast wall balustrade.
In addition, since the protruding reinforcing bars of the precast wall balustrade are embedded and fixed in the concrete of the newly overhanging floor slab, the newly overhanging floor slab and the precast wall balustrade are obtained as an integrated structure. This eliminates the need to fill the gap between the overhanging floor slab and the precast wall balustrade with non-shrinkage mortar or the like.

It is a flowchart which shows the procedure of the construction method of the concrete balustrade of this embodiment. FIG. 3 is a cross-sectional view showing a concrete overhanging floor slab portion 2 of an existing concrete floor slab 1 in the same construction method. 3 is a cross-sectional view showing a state in which an existing overhanging floor slab 2 including a steel bridge protection fence 3 is cut and removed from the existing concrete floor slab 1 of FIG. 2 in the same construction method. FIG. FIG. 4 is a cross-sectional view showing construction of the shoring and assembly of the bottom frame in the same construction method; It is sectional drawing which shows the assembly of the lower side reinforcing-bar 7 in the same construction method. It is sectional drawing which shows temporary placement of 3 A of precast wall balustrades in the same construction method. It is sectional drawing which shows the assembly of the upper side reinforcing-bar 12 of the new overhang floor slab part in the same construction method. It is sectional drawing which shows concrete placing in the same construction method. It is sectional drawing which shows the state of the completion of construction of a precast wall balustrade. It is a perspective view which shows the joint structure provided with the load transmission function in the lane direction edge part of 3 A of precast wall balustrades.

Hereinafter, an embodiment of a method for constructing a concrete balustrade according to the present invention will be described in detail based on the drawings.
This embodiment relates to a method of replacing a steel bridge protection fence laid at the tip of an overhanging deck slab of an existing concrete deck bridge with a concrete wall balustrade. Along with the renewal of the steel bridge protection fence to the concrete wall balustrade, in order to satisfy the required strength of the tip of the overhanging floor slab that supports the concrete wall balustrade in the existing concrete slab, the tip of the overhanging slab tip The updates should be done at the same time.

FIG. 1 is a flowchart showing the procedure of update work according to this embodiment.
This update work consists of the following work procedures S1-S8.
S1. Cut and remove the existing steel bridge protection fence and the tip of the existing overhang floor slab.
S2. Construction of shoring.
S3. Assembling the bottom frame of the newly installed overhanging floor slab.
S4. Assembling the lower reinforcing bars of the new overhang floor slab.
S5. Temporary placement and height/vertical adjustment of precast wall balustrades.
S6. Assembly of the upper reinforcing bars of the newly installed overhanging floor slab.
S7. Formwork is installed where necessary, such as the tip of floor slabs.
S8. Concrete placement and formwork dismantling for newly installed overhanging floor slabs.

Details of each work are described below.
(S1. Cutting and removing the existing steel bridge protection fence and the tip of the existing overhang floor slab)
FIG. 2 is a sectional view showing the concrete overhanging floor slab 2 of the existing bridge 1 (hereinafter referred to as the "existing overhanging floor slab 2"). A protective fence 3 to be removed, such as a steel bridge protective fence, is provided at the tip of the existing overhanging floor slab 2 .

First, as shown in FIG. 3, from the existing bridge 1, the existing overhanging floor slab 2 including the steel bridge protection fence 3 is cut and removed. At this time, from the remaining cut surface of the existing bridge 1, the existing reinforcing bars 4 on the upper edge side of the overhanging floor slab for joint with the reinforcing bars of the newly overhanging floor slab (not shown) are made to protrude. In this embodiment, in order to ensure the strength of the base of the new overhanging floor slabs, it is necessary to increase the cross-sectional dimension of the base of the newly overhanging floor slabs. It is constructed by connecting the rebar 4″ to the post-installed anchor 4′.

(S2. Construction of shoring and S3. Assembly of bottom frame of new overhanging floor slab)
Next, as shown in FIG. 4, construction of the shoring 5 for constructing the new overhanging floor slab and assembly of the bottom frame 6 of the newly overhanging floor slab are carried out. The strength of the shoring 5 shall take into account the weight of the concrete of the newly installed overhanging floor slab and the weight of the precast wall balustrade.

(S4. Assembling the lower reinforcing bars of the newly installed overhang floor slab)
Next, as shown in FIG. 5, the lower reinforcing bars 7 of the new overhanging floor slab are assembled. At this time, the lower reinforcing bar 7 and the reinforcing bar 4″ connected to the post-installed anchor on the cut surface of the existing bridge 1 are connected with a mechanical joint 7′ or the like. The rebar on the lower edge of the newly installed overhanging floor slab is connected to the post-installed anchor by a mechanical joint, but the rebar connection may be a lap joint. do not have.

(S5. Temporary placement and height/vertical adjustment of precast wall balustrades)
After assembling the lower reinforcing bars 7 of the new overhanging floor slab, as shown in Fig. 6, before removing the existing overhanging floor slab 2, the effective width on the road, which was set toward the center of the roadway from the base of the overhanging floor slab, was confirmed. The effective width adjusting material 8 is installed using the reference line to be used. After installing the effective width adjusting member 8, the precast wall balustrade member 3A is lifted by a hydraulic crane, and the precast wall balustrade member 3A is temporarily placed on the bottom frame 6 in accordance with the effective width adjusting member 8. - 特許庁Thereby, the precast wall balustrade member 3A can be easily installed within the reference value of the road alignment.

In addition, as shown in FIG. 6, the bottom of the precast wall balustrade member 3A is protruded with a fully threaded bolt 9 for installing the height adjustment member. 10 is installed on the fully threaded bolt 9. After temporarily placing the precast wall balustrade member 3A, the height of the precast wall balustrade member 3A is checked with a height measuring instrument or the like, and the height is adjusted with the height adjustment member 10 if necessary, and at the same time, the verticality of the precast wall balustrade member 3A. For the purpose of securing, the side of the precast wall balustrade member 3A on the side of the roadway and the road surface on the center side of the road from the cut portion of the existing concrete floor slab 1 are mutually supported by supporting members 11. The support members 11 are preferably adjustable in length so as to adjust the verticality of the precast wall balustrade member 3A, and are preferably installed at two or more locations per precast wall balustrade member 3A. In addition, the supporting member 11 can function not only to ensure the verticality of the precast wall balustrade member 3A but also to prevent overturning.

(S6. Assembling the upper reinforcing bars of the new overhang floor slab)
After fixing the precast wall balustrade members 3A, the upper reinforcing bars 12 of the newly overhanging floor slab are assembled as shown in FIG. Similar to the assembly of the lower reinforcing bars 7, the existing reinforcing bars protruding from the cut surface of the existing concrete floor slab 1 and the upper reinforcing bars 12 of the newly overhanging floor slab are connected by mechanical joints 7' or the like, or The protruding length of the existing reinforcing bars 4 protruding from the cut surface of the concrete floor slab 1 may be made to protrude beyond the length of the lap joint, and may be connected to the reinforcing bars 7 on the side of the newly overhanging floor slab by lap joints, regardless of the reinforcing bar joint structure. .

Although both ends of the precast wall balustrade member 3A in the lane direction are flat surfaces and are not structurally joined, a joint structure having a load transmission function may be employed as shown in FIG. The load transmission function shown in FIG. 10 is provided integrally with a joint convex portion 16 projecting to the other side on one of the joint end surfaces of the precast wall balustrade member 3A that are butted against each other in the lane direction. A groove-shaped joint recess 17 into which the joint protrusion 16 is fitted may be integrally formed on the joint end face of the balustrade 3A.
By installing and fixing the precast wall balustrade members 3A continuously for one bridge or for each span, it becomes easy to check the quality of alignment in the direction of the bridge axis.

(S7. Install formwork at required locations such as the tip of the floor slab, and S8. Concrete placement for the newly overhanging floor slab, dismantling the formwork.)
After installing and fixing the precast wall balustrade members 3A, as shown in Fig. 8, side frames (not shown) are attached to necessary parts such as the side frame 6' at the tip of the new overhanging floor slab on the outside of the precast wall balustrade and the end in the lane direction. ) is installed, and concrete 15 is poured into the space between the bottom frame 6, the cut surface of the existing concrete floor slab 1, and the side frame, thereby constructing a new overhanging floor slab. After the specified curing period has passed, the forms such as the bottom frame and side frames are dismantled. As a result, as shown in FIG. 9, the construction of the concrete wall balustrade is completed at the same time as the renewal of the tip of the overhanging floor slab (construction of the top end of the overhanging floor slab 2A).

As shown in FIG. 7, a reinforcing bar 13 protrudes from the bottom of the precast wall balustrade member 3A. The reinforcing bars 13 projecting from the bottom of the precast wall balustrade member 3A are embedded and fixed in the concrete of the newly overhanging floor slab portion 2A. As a result, the new overhanging floor slab 2A and the precast wall balustrade 3A are constructed as an integral structure.

In this embodiment, precast wall balustrade members 3A having a length in the bridge axis direction of, for example, about 4.0 m are arranged in the bridge axis direction. Reinforcement design such as diameter, length, pitch and number of rebar protruding from the precast wall balustrade members 3A can be the same as when constructing the wall balustrade with cast-in-place concrete, so a special design study is required. It can be said that it is an advantage of this construction method that it does not.

As described above, according to the concrete wall balustrade construction method of the present embodiment, by changing the wall balustrade constructed with cast-in-place concrete to the precast wall balustrade, the work time for the wall balustrade renewal work can be reduced. In particular, it is possible to significantly reduce the work time for wall balustrade renewal work that involves the renewal of concrete overhanging floor slabs.
Further, since the reinforcing bars 13 projecting from the precast wall balustrade 3A are embedded and fixed in the concrete of the newly overhanging floor slab part 2A, the newly overhanging floor slab part 2A and the precast wall balustrade 3A are obtained as an integral structure. For this reason, the work of filling the gap between the overhanging floor slab and the precast wall balustrade with non-shrinkable mortar or the like, which is required in the construction work for renewing only the wall balustrade, becomes unnecessary.
Here, in this embodiment, the reinforcing bars are protruding from the precast wall balustrade. good too. As long as it can be integrated with the newly installed overhanging floor slabs, there is no need to stick to the fixed structure of the precast wall balustrade.
According to the construction method of the concrete wall balustrade of the present embodiment, the construction of the overhanging floor slab and the wall balustrade is completed at the same time, so early traffic restrictions can be lifted.

In the above embodiment, after assembling the bottom frame 9 of the new overhanging floor slab, the lower reinforcing bars 7 of the newly overhanging floor slab are assembled, and then the precast wall balustrade members 3A are temporarily placed on the bottom frame 6. The precast wall balustrade member 3A may be temporarily placed on the bottom frame 6 after assembling the lower reinforcing bars 7 and the upper reinforcing bars 12. That is, the temporary placement of the precast wall balustrade member 3A and the assembly of the lower reinforcing bars 7 and the upper reinforcing bars 12 of the newly overhanging floor slab can be performed in parallel.

Although the construction method of the concrete wall balustrade using the precast wall balustrade accompanying the renewal of the overhanging floor slab end portion of the concrete floor slab of the existing bridge has been described so far, the present invention is limited to this embodiment. Instead, it can be used to construct concrete balustrades on the concrete floor slabs of new bridges.

3A... Precast wall balustrade member 6... Bottom frame 7... Lower reinforcing bar of new overhanging floor slab part 12... Upper reinforcing bar of newly overhanging floor slab part 15... Concrete

Claims (2)

Placing the bottom frame for the concrete floor slab,
A precast wall balustrade member made of concrete constituting the wall balustrade is temporarily placed on the bottom frame with a height adjusting member interposed therebetween to form a gap between the bottom frame and the lower surface of the precast wall balustrade member. At the same time, assembling forms and reinforcing bars other than the bottom frame for the concrete floor slab ,
A method for constructing a concrete wall balustrade, wherein concrete is placed in the concrete placement space for the concrete floor slab, including the gap . 2. The method for constructing a concrete wall balustrade according to claim 1, wherein the precast wall balustrade member has a fixed member for fixing to the concrete floor slab protruding, and is fixed to the concrete placed in the concrete placing space. .

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