JP2734986B2 - Existing bridge repair method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an underbridge for an overbridge, such as an overpass or an overpass, by removing the existing lower structure while reusing and reusing the main girder with new support means. The method relates to a method of repairing an existing bridge to increase the effective space of the section, and can be used, for example, for widening a road crossing a lower portion of an overbridge.

[0002]

2. Description of the Related Art In the case of widening a road, if the pier or footing of an overbridge straddling the road enters a widening lane, some modification is required.

Conventionally, in such a case, the existing bridge as an overbridge is generally completely removed and replaced.

[0004] Also, "Bridges and Foundations", August 200, p. 200, states that a portion of a pier was constructed in a renovation of the Black Lane Road Overpass in Illinois, USA, leaving the main girder of the existing overpass. The renovation example of the removal is described.

[0005] In the above case, the existing bridge 51 (four-span continuous RC girder bridge) as shown in FIG.
In constructing the ramps 56a and 56b outside the a and 55b, as shown in FIGS. 6 and 7, a new pier 62 is provided at a central portion in the bridge axis direction between the side diameters of the existing bridge 51. While the main girder 54 is supported by the rocker bearing 62a,
A reinforced concrete support 63 is also constructed on the main girder 54, and the support 63 and the fulcrum position of the existing pier 52 are connected to the PC steel rod 6.
After connecting with 4 to support the main girder 54, the existing pier 52 is removed and renovated as a new bridge 61 (two span continuous RC cable-stayed bridge).

In this case, the vertical component of the axial force of the PC steel rod 64 is transmitted from the column 63 to the foundation ground from the pier 62 via the main girder 54 and the rocker bearing 62a. The horizontal force is dealt with by providing the cross beam 66 at the fulcrum position of the bridge pier 52 to be removed. An anchor block 65 for taking a reaction force is provided on the opposite side of the column 63, and the PC steel rod 64 is provided.
Is connected to the strut 63.

[0007]

[Problems to be solved by the invention] The existing bridge is completely removed,
When constructing a new bridge, there are problems that the construction cost is high, the construction period (particularly the traffic regulation period) is long, and a large amount of construction waste is generated due to removal.

The rehabilitation example of the black lane road overpass described in the section of the prior art is intended to solve the above-mentioned problem by performing the renovation while leaving the main girder of the existing bridge. I can say.

However, on the other hand, the cross-section of the main girder of the existing bridge is designed in accordance with the supporting method, and the arrangement of reinforcing materials such as reinforcing bars and PC steel (in the case of RC structures) and the arrangement of stiffeners (steel). Structure) is often complicated.

Therefore, if the existing support structure is removed while leaving only the main girder and a new support type is adopted, the stress state of the main girder changes and the cross-sectional performance as the girder may not be sufficiently exhibited. .

For this reason, it is necessary to separately reinforce and stiffen the main girder in addition to simply changing the type of support or the position of the fulcrum. Therefore, the structure becomes more complicated, and problems arise in terms of workability.

For example, in the case described above, a new fulcrum is added to the main girder 54 at the position of the rocker bearing 62a.
Since the main girder 54 supports the column 63 and the column 63 receives a large vertical force from the PC steel bar 64, it is considered that the main girder 54 also needs considerable reinforcement. Although the horizontal girder 66 and the anchor block 65 bear a load on the horizontal force, the stress state between the side diameters of the existing bridge changes, and it is necessary to consider it in the repair.

The method for repairing an existing bridge according to the present invention was invented under the above-mentioned background, and improved the workability and economic efficiency by effectively utilizing the existing main girder, and the accompanying road under the existing bridge. The purpose is to ease traffic regulations during widening work.

[0014]

According to the method for repairing an existing bridge of the present invention, a main girder of an existing bridge is reused by being supported by a new support means, and an existing lower structure supporting the main girder is reused. It is to remove the body.

As a construction procedure, first, a main tower of a cable-stayed bridge is constructed at a predetermined position near an existing bridge.

Next, the fulcrum position of the main girder or the vicinity of the main girder made of diagonal materials in the existing pier as a lower structure or a π-shaped rigid frame bridge is connected to a newly constructed main tower with a tension member such as a PC cable.

Thereafter, by removing the lower structure, the bridge is repaired as a cable-stayed bridge in which the main girder supports the main girder without substantially changing the fulcrum position of the main girder.

Regarding the position of the main tower, it is desirable that the position including the foundation structures such as foundation piles and footing does not obstruct traffic under the existing bridge, and the position of the main girder fulcrum by the existing lower structure or its vicinity. And are positions where they can be connected by a tendon.

By removing the lower structure, the effective space below the main girder is widened, and the widened space can be used for widening the road under the bridge, constructing auxiliary facilities, and the like.

In the case of the cable-stayed bridge type, since the fulcrum position or its vicinity is suspended and supported by the diagonal tendon, the supporting state by the pier or the diagonal before the renovation and especially the stress state related to the horizontal force change. There is. To cope with this, it is possible to cope with the problem by reinforcing the fulcrum position and providing a horizontal girder in the direction perpendicular to the bridge axis at or near the fulcrum position of the main girder.

The invention corresponding to claim 3 of the present application specifies the arrangement of the main tower in the repair method according to claim 1 or 2, and the main tower corresponds to the fulcrum position of the main girder for each fulcrum position. To build.

Also, the invention corresponding to claim 4 of the present application
The renovation method according to claim 1 or 2 stipulates the arrangement of the main tower, wherein the main tower is constructed at an intermediate position in the bridge axis direction between two fulcrum positions of the main girder and two fulcrum positions sandwiching the main tower or the two fulcrum positions. The vicinity and the main tower are connected by tendons.

[0023]

Next, the illustrated embodiment will be described.

FIG. 1 shows an embodiment of the repair method according to claims 1 to 3 of the present application.

The existing bridge 1 is an overbridge that straddles a two-lane road 10 both up and down. A ramen bridge supporting the main girder 3 with diagonal members 2a and 2b using a footing 5 having a foundation pile 4 as a foundation structure. Make up.

When the road 10 under the existing bridge 1 is widened to three lanes in the upper and lower lanes, the existing footing 5 and the diagonal member 2a enter the widening range A (indicated by hatching in the figure). Existing bridge 1 needs to be rehabilitated.

The repair work in the present embodiment is performed in the following procedure.

First, when constructing the main tower 12 of the cable-stayed bridge constituting a new support structure, foundation piles 1
4. Underlay the footing 15, the ground anchor 16, the anchor block 17, etc. for taking the reaction force.

The main tower 12 is constructed on the footing 15.

In order to fix the PC cable 18 of the cable-stayed bridge in the transverse direction of the main girder 3 by a supporter or a suspension supporter rising from the ground surface at or near the intermediate fulcrum supported by the existing diagonal member 2a. Is provided.

The main tower 12, the cross beam 13, and the main tower 12
A PC cable 18 is stretched between the cable 11 and the anchor block 17 and is fixed in a tension state.
Complete the structural system.

A part of the existing footing 5 and the diagonal members 2 a that fall within the support and widening range are removed. In addition,
As in the illustrated example, the diagonal members 2b that do not enter the widening range and the foundation pile 4 that supports the footing 5 may be left alone.

FIG. 2 is a sectional view in the direction perpendicular to the bridge axis corresponding to FIG. 1. The left half is a cross section at the position of the main tower 12, and the right half is a PC.
It is a cross section of the cable 18 fixing position.

In the drawing, reference numeral 19 denotes a shear connector for integrating the existing main girder 3 and the horizontal girder 13 at the fulcrum position, and reference numeral 20 denotes a laterally tightened PC steel material passed through the lower part of the horizontal girder 13.

FIG. 3 shows an embodiment of the repair method according to the first, second and fourth aspects of the present invention.
FIG. 4 is a cross-sectional view in a direction perpendicular to the bridge axis corresponding to FIG. The conditions of the existing bridge 1 and the renovation are the same as in the above embodiment.

In the above embodiment, the main tower 12 of the cable stayed bridge is
In this embodiment, the main tower 12 'of the cable-stayed bridge is constructed at the median strip position of the road 10 under the bridge, and the intermediate supports on both sides of the main tower 12' are provided in this embodiment. And the main tower 12 'are connected by a PC cable 18' as a tension member to form a cable-stayed bridge as a new bridge 11 '.

The repair work in this embodiment is performed in the following procedure.

First, a foundation pile 14 ′, a footing 15 ′, a ground anchor 16 ′ for taking a reaction force at both ends of the main girder 3, an anchor block 17 ′, etc. at the construction position of the main tower 12 ′ of the cable-stayed bridge. The substructure will be constructed.

The main tower 12 ′ is built on the footing 15 ′.

The main girder 3 is provided at or near two intermediate fulcrums supported by the existing diagonal members 2a by a shoring or suspension shoring, respectively, which is raised from the ground surface.
A cross beam 13 'is provided in the transverse direction for fixing the PC cable 18' of the cable-stayed bridge.

P between the main tower 12 ′ and both cross beams 13 ′
The C cable 18 'is stretched, and the end of the PC cable 18' is fixed to the anchor block 17 'in tension, thereby completing the structural system of a new bridge 11' as a cable-stayed bridge.

A part of the existing footing 5 and the diagonal member 2 a that enter the support and widening range are removed.

This embodiment has the advantage that one main tower 12 ′ constructed using the space of the median strip can support both intermediate supports of the main girder 3, but has a large central span of the existing bridge 1. And the scale of the cable-stayed bridge including the main tower 12 'is increased.

[0044]

According to the present invention, the span can be expanded by repairing the existing bridge, and the space under the girder can be used effectively.

Since the existing main girder is reused to form a new overbridge, construction costs and materials can be reduced.

The construction period is shorter than when a new bridge is replaced, and the period of traffic regulation can be shortened.

Since the fulcrum position of the main girder does not change and the sectional force does not increase or decrease when the design load is applied, the PC in the bridge axis direction
There is no need to change the arrangement of steel materials and reinforcing bars, the amount of steel materials, etc., and there is little waste in design.

The amount of construction waste material due to dismantling is small.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment (corresponding to claim 3) of the present invention.

2 is a cross-sectional view (right and left cross-sectional positions are different) in a direction perpendicular to the bridge axis corresponding to FIG.

FIG. 3 is a side view showing an embodiment (corresponding to claim 4) of the present invention.

FIG. 4 is a sectional view in a direction perpendicular to the bridge axis corresponding to FIG. 3;

FIG. 5 is a side view of an existing bridge (overpass) before renovation in a conventional example.

FIG. 6 is a side view of the overpass after the repair corresponding to FIG. 5;

FIG. 7 is an explanatory diagram of a support structure corresponding to FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Existing bridge, 2a, 2b ... Diagonal material, 3 ... Main girder, 4 ... Foundation pile, 5 ... Footing, 10 ... Road, 11 ... New bridge, 12
... Main tower, 13 ... Girder, 14 ... Foundation pile, 15 ... Footing, 16 ... Grand anchor, 17 ... Anchor block, 18 ... PC cable, 19 ... Shear connector, 20
... PC steel laterally tightened, 51 ... Existing bridge, 52 ... Pier, 53 ...
Abutment, 54 ... Main girder, 55a, 55b ... Road, 61 ... Refurbished bridge, 62 ... New pier, 63 ... Reinforced concrete column, 64 ... PC steel rod, 65 ... Anchor block, 66 ...
Horizontal girder

Claims (4)

(57) [Claims] 1. A method of repairing an existing bridge in which a main girder of an existing bridge is reused by being supported by new support means, and an existing lower structure supporting the main girder is removed. By constructing the main tower of the cable stayed bridge at a predetermined position near the bridge, connecting the fulcrum position of the main girder by the existing lower structure or its vicinity and the main tower with a tendon, and removing the lower structure A method of repairing an existing bridge, wherein the main girder is supported by the main tower as a new supporting means without substantially changing the fulcrum position of the main girder. 2. A cross girder perpendicular to the bridge axis is provided at or near a fulcrum position of the main girder to reinforce the fulcrum position.
The existing bridge repair method described. 3. The method according to claim 1, wherein the main tower is constructed for each fulcrum position corresponding to the fulcrum position of the main girder. 4. The main tower is constructed at an intermediate position in the bridge axis direction between two fulcrum positions of the main girder, and the main tower is connected to the two fulcrum positions sandwiching the main tower or the vicinity thereof with a tendon. The existing bridge repair method described.