JP2016037774A - Erection method for bridge girder, and bridge body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an erection method for a bridge girder, and a bridge body, which enable simple and inexpensive execution of bridge body erection work.SOLUTION: An erection method for a bridge girder includes: a bridge body forming step of forming a bridge body 6 by connecting a plurality of new bridge girders 3, 3 and 3 together; a tensioning step of introducing a tensioning force into a tendon inserted through the bridge body 6; and an erection step of placing the bridge body 6 on a plurality of bridge piers 4, 4,.... In the bridge body forming step, the bridge body 6 is formed in such a shape that both ends are positioned on the upside with respect to a central part in a bridge axis direction. In the erection step, the bridge body 6 is erected so as to be flattened.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bridge girder construction method and a bridge body.

In some cases, the bridge girder is replaced while the existing pier remains, as a repair work for an aging bridge.
As a bridge girder replacement method, for example, as shown in Patent Document 1, an erection gutter is installed above the existing girder along the axis of the bridge, and the existing girder is removed by a suspension device that moves the erection gutter. In addition, there is a construction method for installing a new bridge girder by the suspension device.

  However, the conventional bridge girder replacement method requires replacement of a new bridge girder for each existing bridge girder (every span), and therefore, it takes time to perform the work for replacing the bridge with a large number of bridge girder.

On the other hand, a bridge girder (bridge body) in a multi-span continuous bridge is constructed by placing a bridge body in which a plurality of bridge girders are connected across a plurality of bridge piers.
In addition, when prestress is introduced to the bridge body, it is general that a force that tries to warp in a bow shape so that the center part of the bridge body is located above the both ends by the secondary force. .

JP 2003-253623 A

  In the conventional bridge body construction method for multi-span continuous bridges, the fulcrum reaction force acting on the pier supporting both ends of the bridge body is larger than the fulcrum reaction force acting on the pier supporting the center part, The design strength of the pier may be exceeded. In this case, it is necessary to reinforce the pier, but the work is time consuming and expensive.

  From such a viewpoint, an object of the present invention is to provide a bridge girder erection method and a bridge body that can perform bridge girder erection work easily and inexpensively.

  In order to solve the above-mentioned problems, the bridge girder construction method of the present invention is a bridge body forming step of connecting a plurality of newly installed bridge girders to form a bridge body, and a tension force is introduced into the tension member inserted through the bridge body. A tensioning step, and a laying step of placing the bridge body on a plurality of piers. In the bridge body forming step, both ends of the bridge body are located above the center in the bridge axis direction. It forms so that it may be located, and it is constructed in the said construction process so that the said bridge body may become flat.

According to such a bridge girder construction method, the bridge body is constructed so as to be flat, so that the fulcrum reaction force acting on the plurality of bridge piers can be applied equally.
For this reason, it is possible to omit or reduce the work of reinforcing the bridge pier, etc., and to shorten the construction period and reduce the construction cost.

  In the bridge body forming process, a plurality of jacks are arranged on the existing bridge girder, and the bridge body is formed by using these jacks, thereby eliminating the trouble of transporting the bridge body and making the erection process more efficient. Can be done.

In the erection step, the existing bridge girder is lowered and the plurality of jacks are contracted to lower the bridge body so that the existing bridge girder is removed and the new bridge girder (bridge body) is erected simultaneously. Work efficiency is further improved.
At this time, if the contraction amount of the jack disposed at the end portion of the bridge body is larger than the contraction amount of the jack disposed at the center portion of the bridge body, the bridge body is laid flat. Can do.

  In addition, the bridge body of the present invention is formed by connecting a plurality of bridge girders, and is characterized in that it is formed in a state of being warped so that both end portions are located on the upper side of the center portion. Yes.

  According to such a bridge body, the fulcrum reaction force acting on a plurality of bridge piers can be equalized when the bridge body is installed. Therefore, the pier reinforcement work can be omitted or reduced.

  According to the bridge girder construction method and the bridge body of the present invention, the bridge girder construction work can be performed easily and inexpensively.

(A)-(d) is a front view which shows the operation | work condition of the construction method of the bridge girder of this embodiment. (A) is the cross-sectional view of (b) of FIG. 1, (b) is the cross-sectional view of (d) of FIG.

In the present embodiment, as shown in FIG. 1, a construction method of a bridge girder that replaces the existing bridge girder 4 of the existing bridge 3 with the bridge body 1 will be described.
The bridge body 1 is formed by connecting a plurality of new bridge girders 2, 2, and 2. The bridge body 1 before erection is formed in a warped state so that both end portions are located on the upper side of the central portion in the bridge axis direction.

In this embodiment, the existing bridge girder 4 for three spans supported by the four piers 5, 5,.
In addition, the length (number of spans) of the existing bridge girder 4 to be replaced is not limited.

  The existing bridge girder 4 is formed of so-called ordinary concrete. In addition, the material of the existing bridge girder 4 is not limited.

  The bridge girder construction method includes a jack disposing process, a supporting process, a bridge body forming process, a tensioning process, and an erection process.

  The jack disposing step is a step of disposing a plurality of first jacks 6, 6,... Below the existing bridge girder 4 as shown in FIG.

In the present embodiment, a total of four first jacks 6, 6,... Are arranged between the piers 5 adjacent in the bridge axis direction. Specifically, two rows (see FIG. 2A) of two rows of jacks composed of two first jacks 6 and 6 arranged at an interval in the bridge axis direction are arranged along the bridge crossing direction.
Therefore, in this embodiment, 12 first jacks are arranged for the existing bridge girder 4 (3 diameters) to be replaced.

The first jack 6 is disposed close to the pier 5. That is, the first jacks 6, 6,... Arranged between the pair of bridge piers 5, 5 are arranged at intervals in the bridge axis direction.
The arrangement and number of the first jacks 6 are not limited.

  In the present embodiment, a large hydraulic jack (stage jack) is used as the first jack 6. The configuration of the first jack 6 is not limited.

  In the supporting step, as shown in FIGS. 1A and 1B, the existing bridge girder 4 is supported by the first jack 6, and the fulcrum portion (joint portion with the pier 5) 7 of the existing bridge girder 4 is cut. It is a process.

The existing bridge girder 4 is supported from below by a first jack 6 disposed below (Fig. 1 (a)). When the first jack 6 is extended to support the existing bridge girder 4, the fulcrum portion 7 of the existing bridge girder 4 is cut and removed ((b) of FIG. 1).
By removing the fulcrum part 7, the existing bridge girder 4 is divided into a plurality of divided bridge girders 4a, 4a, 4a shorter than the interval between the piers 5.

The bridge body forming step is a step of forming a bridge body 1 by connecting a plurality of new bridge girders 2, 2 and 2 as shown in FIG.
In this embodiment, three new bridge girders 2, 2, and 2 are connected in the direction of the bridge axis to form the bridge body 1, but the number of new bridge girders 2 that form the bridge body 1 is not limited.

The bridge body 1 is formed on the existing bridge girder 4 using the second jacks 8, 8,... Arranged on the existing bridge girder 4.
As shown in FIGS. 1B and 2A, each new bridge girder 2 is supported by four other second jacks 8, 8,. Connected. That is, the bridge body 1 is formed in a state where it is supported by twelve second jacks 8, 8,.

  The bridge body 1 is formed so that both end portions are positioned above the center portion in the bridge axis direction. That is, while the new bridge girder 2 at the center is horizontally supported, the new bridge girders 2 and 2 arranged on both sides (left and right in FIG. 1 (b)) By adjusting, the bridge body 1 is formed to be inclined so as to become lower toward the center side, and to be convex downward as a whole.

In this embodiment, the new bridge girder 2 is made of high-strength concrete. Therefore, the new bridge girder 2 is formed thinner than the existing bridge girder 4.
In addition, the material which comprises the new bridge girder 2 is not limited.

  A gap filling material (not shown) is interposed in the joint portion (butting portion) between the newly installed bridge girders 2. Moreover, joining of the newly installed bridge girders 2 is performed by a tension force (prestress) introduced via a tension member (not shown).

The tensioning process is a process of introducing a tensioning force to a tensioning material (not shown) inserted through the bridge body 1.
By introducing a tension force to the tension material, the end faces of the newly installed bridge girders 2 and 2 are pressure-bonded (total compression structure).
In addition, the material which comprises a tension | tensile_strength is not limited, For example, what is necessary is just to use PC steel wire, PC strand, a PC steel rod, etc.

  Since the tension members are arranged in the lower part of the bridge body 1, when a tension force is introduced into the tension members, downward force acts on both ends of the bridge body 1 in the bridge axis direction. Since it is supported by the two jacks 8, 8, the bridge body 1 is maintained in a warped state.

  The erection process is a process of removing the existing bridge girder 4 and placing the bridge body 1 on the plurality of piers 5, 5,.

In the erection step, the bridge body 1 is lowered together with the existing bridge girder 4 by contracting the first jacks 6, 6,... As shown in FIG.
At this time, the twelve first jacks 6, 6,... Are controlled so as to descend simultaneously through a control system (not shown).

  The control system collects jack stroke and jack reaction force data of each first jack 6 and performs management based on this data. If an error occurs during descending, all the first jacks 6, 6,... Are stopped and corrected.

  Moreover, on the existing bridge girder 4, the 2nd jacks 8, 8, ... are contracted, and the bridge body 1 is lowered. The second jacks 8, 8,... May be contracted after the descent of the existing bridge girder 4 by the first jacks 6, 6,. May be.

  When the bridge body 1 is lowered, the contraction amount of the second jack 8 disposed on the end side in the bridge axis direction of the bridge body 1 is larger than the contraction amount of the second jack 8 disposed on the center side. Adjust while adjusting. If it carries out like this, as shown to (d) of FIG. 1 and (b) of FIG. 2, when the bridge body 1 is constructed on the piers 5, 5, ..., the upper surface of the bridge body 1 will be in a flat state.

  When the bridge body 1 is installed on the piers 5, 5,..., The control is performed while simultaneously controlling the twelve second jacks 8 using a control system (not shown).

  The control system collects jack stroke and jack reaction force data of each second jack 8 and performs management based on this data. If an error occurs during lowering of the second jack, all the second jacks 8, 8,... Are stopped and corrected.

  The divided bridge girders 4a, 4a, 4a lowered along with the piers 5, 5,... Of the bridge body 1 are placed on a transporting vehicle (not shown) arranged in advance and carried out.

According to the bridge girder erection method of the present embodiment, the bridge body 1 is installed so that the upper surface is flat, so that the fulcrum reaction force acting on the plurality of bridge piers 5, 5,.
That is, in order to straighten the bridge body 1 until the bridge body 1 is placed on the piers 5 and 5 while prestress is introduced in a state where the bridge body 1 is warped downward, It is possible to prevent stress from being concentrated on the piers 5 and 5 on which the ends of the body 1 are placed.

  Therefore, it is possible to omit or reduce the labor for reinforcing the pier 5 and the like, and it is possible to shorten the construction period and reduce the construction cost.

In addition, since a plurality of new bridge girders 2, 2, and 2 are connected and installed simultaneously across multiple spans, the workability is excellent.
Moreover, since the bridge body 1 is formed on the existing bridge girder 4, labor can be significantly reduced compared with the case where the bridge body 1 is formed and transported in another place.

  In addition, by lowering the existing bridge girder 4 and lowering the bridge body 1, the bridge body is installed on the piers 5, 5,..., So that the existing bridge girder 4 is removed and the new bridge girder 2, 2, 2 (bridge body 1). Can be performed at the same time, and as a result, the labor of the work can be greatly reduced.

Moreover, according to the bridge body 1 of this embodiment, compared with the conventional multi span continuous bridge, the number of tendons can be reduced.
In order to improve the stress of the girder, the multi-span continuous bridge has a tension member arranged eccentrically near the upper edge on the fulcrum and near the lower edge on the fulcrum, but when tension is introduced in this state, The reaction force at each fulcrum fluctuates. Therefore, in order to avoid reinforcement of existing piers, it is necessary to arrange the tension members so that there is no eccentricity of the tension members. Therefore, it is necessary to increase the number of tendons as compared with the normal arrangement.
On the other hand, according to the bridge body of the present embodiment, since it can be arranged of a tension material capable of effectively acting the eccentric moment, than the multi-span continuous bridge in the case as described above The number of tendons can be reduced.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and the above-described components can be appropriately changed without departing from the spirit of the present invention.

For example, the form of the pier of the existing bridge is not limited to the T-shaped pier, and may be a wall-type pier, for example.
The form of the bridge girder (existing bridge girder and new bridge girder) is not limited, and a box girder, I-shaped girder, plate girder, etc. may be appropriately selected and adopted.

In the embodiment, the fulcrum part of the existing bridge girder is cut in the support process before the bridge body forming process, but the cutting timing of the fulcrum part of the existing bridge girder is not limited as long as it is before the installation process.
The method for carrying out the existing bridge girder 4 is not limited. For example, the divided bridge girder 4a may be further divided and carried out on the ground.

  In the above embodiment, the case where the existing bridge girder and the bridge body are lowered at the same time to remove the existing bridge girder and the new bridge girder at the same time has been described. However, the bridge body may be constructed after the existing bridge girder is removed. .

  Moreover, although the said embodiment demonstrated the case where an existing bridge girder was replaced, you may employ | adopt the construction method of the bridge girder of this invention when constructing a new bridge.

DESCRIPTION OF SYMBOLS 1 Bridge body 2 Newly installed bridge girder 3 Existing bridge 4 Existing bridge girder 5 Bridge pier 6 First jack 7 Support point 8 Second jack (jack)

Claims (4)

A bridge body forming process for connecting a plurality of newly constructed bridge girders to form a bridge body;
A tensioning process for introducing tension into the tension material inserted through the bridge body;
A bridge girder erection method comprising the erection step of placing the bridge body on a plurality of piers,
In the bridge body forming step, the bridge body is formed such that both ends are located on the upper side of the center part in the bridge axis direction,
In the construction step, the bridge girder construction method is characterized in that the bridge body is constructed so as to be flat.   2. The bridge girder erection method according to claim 1, wherein, in the bridge body forming step, a plurality of jacks are arranged on an existing bridge girder and the bridge body is formed using the jacks.   In the erection step, the existing bridge girder is lowered, and the contraction amount of the jack disposed at the end portion of the bridge body is larger than the contraction amount of the jack disposed at the center portion of the bridge body. The bridge girder erection method according to claim 2, wherein the bridge body is lowered while being adjusted. A bridge body formed by connecting a plurality of bridge girders,
A bridge body characterized in that the bridge body is formed in a warped state so that both end portions are located on the upper side of the center portion.

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