JP2004324164A - Method of constructing corrugated steel web pc bridge closure section - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct a bridge body at a closure section for which timbering cannot be erected on the ground, by employing a simple girder, at the time of erecting a corrugated steel web bridge in an overhanging manner. <P>SOLUTION: There is provided a method of constructing a corrugated steel web PC bridge closure section, according to which first the simple girder 40 is erected across the closure section, and a corrugated steel web 10 is erected across the closure section by using the girder 40, followed by sequentially placing lower floor slab concrete 20 from the side of an overhanging bridge body, to thereby construct a temporary girder formed of the lower floor slab concrete 20 and the corrugated steel web 10. Then the girder 40 is removed, and upper floor slab concrete 30 is sequentially placed from the side of the constructed bridge body 110 by using the temporary girder, followed by straining continuous outside cables, to thereby construct the bridge body at the closure section. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method of constructing a closed portion between side spans or a center span in erection of a corrugated steel web PC bridge.
[0002]
[Prior art]
Generally, when a bridge can be built up from the ground at the construction point of the closed part, the support is formed and the bridge is constructed on this bridge. Is done. However, in some cases, it is not possible to install a shoring, in which case a beam type shoring is spanned between the abutment and the end of the overhanging girder to support the concrete load and construct the bridge between the side spans. Is adopted.
[0003]
In addition, the closing portion between the center spans is usually cast with concrete between the ends of the existing overhanging girders by bridging a formwork. However, depending on the bridge condition on the terrain, the closed portion between the center diameters may be long due to span splitting. In this case, it is inevitable to use a beam type shoring between the ends of the overhanging girders to support the concrete load and to construct the closed bridge between the center spans.
[0004]
In the above case, the beam-type support member needs a function of supporting all loads during the construction period of the closing portion. FIGS. 10 and 11 are side views in the case of constructing a bridge body 115 having side spans as such a closed portion. When there is a situation where it is not possible to erect a shoring from the ground when constructing a bridge body 115 between side spans between the overhang bridge body 110 overhanged from the pier 100 and the abutment 50. Use beam type shoring. FIG. 10 shows a case where the construction length of the bridge body 115 at the closed portion between the side diameters is relatively short, and the beam type support is provided between the end 111 of the bridge body 110 overhanged and the abutment 50. An H-shaped steel 130 is erected as a work, and all the construction load of the bridge body 115 between the side spans is borne by the H-shaped steel 130.
[0005]
FIG. 11 shows an example in which the construction length of the bridge body 115 at the closing portion (side span) is long. A large-scale truss beam 140 is used as a beam type support, and the large-scale truss beam 140 is used. , The work scaffold 141 is suspended, and the construction load of the bridge 115 at the closing portion is entirely borne by the scaffold, and the bridge 115 is erected.
[0006]
In such a case, for example, the girder of the closing portion is divided into a plurality of block girder, support bases are provided on both sides of the construction span, temporary beams are bridged, and the predetermined girder is provided by an erection vehicle provided with the block girder on the temporary girder. There is a technique in which a bridge girder is installed at a position, a block girder is sequentially suspended by a temporary beam and supported, and each block girder is connected and integrated into a simple beam to construct a bridge body at a closed portion (for example, see Patent Document 1). .).
[0007]
In this technique, a bridge girder installed on a span to be constructed is suspended as a simple beam. Each block is successively extended and overhanged by wagen construction. This method requires a strong temporary girder to support all concrete loads.
[0008]
[Patent Document 1]
Japanese Patent No. 2517211 (page 2-3, FIG. 1)
[0009]
[Problems to be solved by the invention]
The present invention relates to a technique relating to the construction of a closed bridge body of a corrugated steel web PC girder, and is a construction method that does not require a large beam-type supporting material for supporting a full load of concrete, or a beam-type supporting material. It is an object of the present invention to provide a construction method which can be constructed by a work supporting structure which reduces a load acting on a work and which is reduced in weight.
[0010]
That is, the present invention is a technique applied when a bridge having a lightweight girder using a corrugated steel web as a bridge body is erected, and a condition in which a closed portion cannot be constructed by a support from the ground. It is necessary to install only the corrugated steel web of the bridge body of the closed part during the erection work under the construction and to carry out the concrete load on this corrugated steel web, or to carry the full construction load. It is intended to achieve the above-mentioned purpose by using a simple work support.
[0011]
[Means for Solving the Problems]
The present invention has been developed in order to solve the above-mentioned problems, and the technical means is for corrugated steel plates to bear a main girder concrete load in the closed portion when constructing a closed bridge body of a corrugated steel web PC bridge. A method of constructing a closed section of a corrugated steel web PC bridge, comprising laying a web connection body, placing concrete on a lower slab, then placing concrete on an upper slab, stretching a continuous outer cable, and tensioning. It is.
[0012]
In the present invention, when constructing a bridge body in which the closed portion is a side span, one end of the corrugated steel web connection body is connected to the tip of the overhanging bridge body, the other end is placed on the abutment, and It is a construction method of a corrugated steel web PC bridge closing portion characterized by placing floor slab concrete, and in this case, the lower floor slab concrete placement is performed sequentially from the overhanging bridge body side. When the local stress at the suddenly changing section between the concrete and the corrugated steel web web is relaxed, the construction can be easily and rationally performed, and is particularly suitable for a long span. In addition, it is preferable that the placing of the upper floor slab concrete be sequentially performed from the side of the overhanging bridge body for the same reason as described above.
[0013]
In the case of constructing a bridge with a closed part with a central span, the closing distance of the closed part is usually small, so it is possible to simply close the form by attaching a formwork between the overhanging bridges. , The closing distance between the center diameters may be increased due to circumstances such as span assignment. In that case, the following invention is applied.
[0014]
That is, in the present invention, when constructing a bridge body in which the closed portion is a center span, both ends of the corrugated steel web linked body corresponding to the closing distance between the center spans are attached to the tip of the overhanging bridge body. This is a method for constructing a closed section of a corrugated steel web PC bridge, which is connected to each other and casts a lower deck slab concrete. In this case, if the casting of the lower slab concrete or the placing of the upper slab concrete is to be sequentially performed from one or both of the overhanging bridge bodies, a closed part bridge body having a particularly long central diameter is particularly preferable. It is suitable when constructing.
[0015]
In the case of the construction of the closing portion, if necessary, using a working girder for erection of the corrugated steel web connection body, after placing the lower slab concrete, by removing the working girder to the lower slab concrete. What is necessary is just to give a compressive stress degree and relieve the tensile stress degree of the lower slab concrete. In this case, making full use of the characteristics of the corrugated steel web PC bridge, the provisional girder consisting of the corrugated steel web and the lower slab is formed using a simple work girder that can only perform the corrugated steel web and its lower slab concrete. The provisional girder was formed so that the provisional girder could support the load during the construction of the upper slab, and the girder could be removed after the provisional girder was formed. Therefore, girder does not require large girder. This is achieved by cleverly utilizing the properties of corrugated steel webs having high longitudinal stiffness and light weight.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 12 is a side view of a bridge according to an embodiment to which the present invention is applied. It is a continuous ramen bridge with a total length of 495m and a span of four. Bridges are erected from left and right on piers 100, 100a, 100b erected on the respective foundations 101, 101a, 101b to form overhang bridges 110, which are connected to each other at an intermediate joint between the piers. . At the left end in the figure, a bridge body 115 as a closed portion is constructed on the side span closed portion 120 between the overhang bridge body 110 and the abutment 50.
[0018]
In the embodiment, since a valuable plant is growing below the side span closing portion 120, it is not possible to construct a shoring from the ground. In addition, construction conditions are restricted because the tunnel entrance is adjacent to the abutment. The length of the span of the closing part 120 is about 31 m on the up line and about 46 m on the down line. Normally, a large truss girder that bears all the load during construction of the bridge body is newly manufactured and bridged using this large truss girder. I needed to.
[0019]
Here, in consideration of workability and economy, etc., a construction technique for pre-installing a corrugated steel web was developed. According to this construction technique, the main girder concrete load in the bridging process of the closed bridge can be applied to the corrugated steel web, and a large truss girder is not required.
[0020]
In some cases, it is possible to construct the closure using a small-scale girder capable of supporting only the corrugated steel sheet web and the lower floor slab concrete construction scaffold. Therefore, there is no need to produce a large girder.
[0021]
1 and 2 show a construction procedure of a bridge body of a closed portion between side diameters according to the embodiment. This embodiment shows an example in which a working girder 40 is used.
[0022]
According to the present invention, the resistance section at the time of placing the lower slab concrete is only the corrugated steel sheet, and the resistance section at the time of placing the upper slab concrete is a composite girder (temporary girder) of the corrugated steel sheet and the lower slab concrete.
[0023]
First step: As shown in FIG. 1A, the legs 41, 42 are erected on the tip 111 of the existing overhanging beam 110 and the abutment 50, and the girder 40 is bridged. 10 is suspended from the side span and closed.
[0024]
Second step: As shown in FIG. 1 (b), one end of the corrugated steel web 10 is connected to the tip 111 of the existing overhanging beam 110, and the other end is placed on the abutment 50.
[0025]
Third step: As shown in FIG. 1C, a scaffold for construction of the lower slab concrete 20 is suspended using the girder 40, and the formwork 21 of the lower slab concrete 20 is attached to the corrugated steel sheet web 10, and The floor slab concrete is cast in the direction indicated by the arrow 22 from the side of the existing overhang girder 110 about every 6 m in length as indicated by each casting length 23. Construction is carried out for each appropriate casting length to relieve the local stress at the suddenly changing section between the concrete and the corrugated steel web link. At this time, the casting load of the lower slab concrete is supported by the corrugated steel sheet web 10. The lower deck slab concrete 20 is constructed while being reinforced with a reinforced PC steel material while being sequentially integrated. The composite girder (temporary girder) of the corrugated steel sheet web 10 and the lower slab concrete 20 between the side diameters is designed to be able to bear the load at the time of placing the upper slab concrete.
[0026]
Fourth step: As shown in FIG. 2D, the girder 40 is removed as shown by an arrow 43. By removing the girder 40, a compressive stress is applied to the lower slab concrete 20, and the tensile stress of the lower slab concrete 20 is reduced.
[0027]
Fifth step: As shown in FIG. 2E, the upper slab concrete 30 is sequentially driven from the existing overhanging girders 110 side. The construction of the upper slab concrete is performed by attaching a formwork of the upper slab concrete 30 to a provisional girder composed of the corrugated steel web 10 and the lower slab concrete 20 and, as indicated by each casting length 31, every 6 m in length. Concrete is poured and proceeds as indicated by arrow 32. At this time, the provisional girder supports the concrete load.
[0028]
Sixth step: As shown in FIG. 2 (f), a continuous outer cable 33 is stretched and tightened to complete the bridge construction of the closed portion.
[0029]
【Example】
FIG. 12 shows an overall general view of the embodiment. The embodiment is a continuous ramen bridge having a total length of 495 m and a span of four. The side span closure is adjacent to the tunnel and has a steep slope 121 in terms of topography, and on this slope there are nationwide valuable plants, such as Ichimochisou, Ohikiyomogi and Himekonukagusa. Therefore, it was not necessary to install a pier on the slope, and the long span was closed at the side span closure.
[0030]
As a result, a PC extra-dosed bridge applicable to a long span was selected, and a corrugated steel web structure was adopted to further reduce dead load. 12, piers 100, 100a, and 100b are erected from the left side of FIG. 12, each span is about 140 m, 170 m, 120 m, and 70 m. A main tower 102 is provided on the pier 100, and a cable stay cable 112 is installed. are doing.
[0031]
The main girder is the world's first three-chamber box girder cross section of a corrugated steel web bridge as shown in the cross section in FIG. The width of the upper slab is about 20 m, the width of the lower slab is about 14 m, and the girder height is 4.5 to 7.5 m. In addition, the steel-concrete composite structure was actively adopted, and the main girder side anchoring part of the diagonal material was made of a steel diaphragm structure to reduce its own weight.
[0032]
The upper and lower flanges of the corrugated steel web at the middle part of the girder cross section are discontinuous with a thickness of 19 mm and a flange width of 360 mm in the girder cross section of the general part, and the upper flange of the girder of the closed part has a thickness of 40 to 46 mm. The width of the lower flange is 750 mm, the thickness of the lower flange is 40 mm, and the width of the flange is 500 mm.
[0033]
In terms of construction, there is a restriction that no support can be erected at the closed part, so for the construction of the closed part of about 30 m, the corrugated steel web is erected in advance and the main girder concrete load is loaded on the corrugated steel web. A new construction method was adopted.
[0034]
Regarding the closed portion, the axial stress of the slab concrete by plane frame analysis (FRAME) is shown in FIGS. 4 to 6, and the axial stress of the steel flange is shown in FIGS. The horizontal axis indicates the distance (m) from the main tower, the vertical axis indicates the axial stress (N / mm ² ), + indicates compression, and − indicates tension. In the figure, the symbol ◆ indicates the stress level at the upper edge, and the symbol □ indicates the stress level at the lower edge. Eight pre-grouted steel materials (1S28.6) were placed at the time of placing concrete on the lower floor slab, and the concrete tensile stress was controlled to 2.0 N / mm ² or less.
[0035]
FIG. 4 shows the degree of axial stress σc of the concrete after placing the concrete on the lower slab. The stress is small in both the steel flange of the lower slab and the entire cross section of the main girder. FIG. 5 shows the axial stress degree σc of the concrete after the girder was removed, and the stress was within the allowable range in both the lower deck slab steel flange and the entire cross section of the main girder. FIG. 6 shows the axial stress degree σc of the concrete after placing the upper slab. The stress is within the allowable range in both the lower slab steel flange and the entire cross section of the main girder.
[0036]
FIG. 7 shows the axial stress degree σx of the steel flange after casting the lower slab concrete. The stress is small in the steel flange, the lower slab steel flange, and the entire cross section of the main girder. FIG. 8 shows the axial stress degree σx of the steel flange after the girder was removed, and the stress was within the allowable range for the lower floor slab steel flange and the entire cross section of the main girder. FIG. 9 shows the axial stress degree σx of the steel flange after the upper slab is cast. The stress is within the allowable range in both the lower slab steel flange and the entire cross section of the main girder. The maximum compressive stress of the upper edge of the steel flange is about 170 N / mm ^{2 at the} time of placing concrete on the upper floor slab.
[0037]
【The invention's effect】
According to the present invention, in the construction of the closing portion of the overhanging bridge body, the corrugated steel sheet is erected in advance and the main girder concrete load is borne, thereby omitting or reducing the weight of a large beam type support structure. Is now available. In addition, by combining the main girder concrete divided and cast on the corrugated steel sheet web erected in advance as needed, and increasing the cross-sectional composition stepwise, it is possible to reduce the stress degree generated in the steel member and the joint. Furthermore, at the stage where the placing of the lower slab concrete is completed, the girder used for erection of the corrugated steel plate is removed, so that a compressive stress can be applied to the lower slab concrete.
[Brief description of the drawings]
FIG. 1 is a process chart showing a procedure for constructing a bridge body of a closed portion according to an embodiment.
FIG. 2 is a process diagram showing a procedure for constructing a bridge body of a closing portion according to the embodiment.
FIG. 3 is a cross-sectional view of a corrugated steel web girder.
FIG. 4 is a graph showing an axial stress level of floor slab concrete.
FIG. 5 is a graph showing an axial stress degree of the slab concrete.
FIG. 6 is a graph showing an axial stress level of floor slab concrete.
FIG. 7 is a graph showing an axial stress degree of a steel flange.
FIG. 8 is a graph showing an axial stress degree of a steel flange.
FIG. 9 is a graph showing an axial stress degree of a steel flange.
FIG. 10 is a side view showing construction of a bridge body of a closing portion.
FIG. 11 is a side view showing construction of a bridge body at a closing portion.
FIG. 12 is a side view of the bridge according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Corrugated steel sheet web 20 Lower deck slab concrete 21 Formwork 22 Arrow 23 Casting length 30 Upper deck slab concrete 31 Casting length 32 Arrow 33 Continuous cable 40 Girder 41, 42 Leg 43 Arrow 50 Abutment 100 Bridge pier 101 Foundation 102 Main tower 110 bridge body 111 end 112 cable-stayed cable 115 bridge body 120 closing part 121 slope 130 H-section steel 140 truss beam 141 work scaffold

Claims (8)

In constructing the bridge part of the corrugated steel web PC bridge, a corrugated steel web connecting body to bear the main girder concrete load is erected in the closed part, the lower slab concrete is poured, and then the upper slab concrete is laid. A method of constructing a closed section of a corrugated steel web PC bridge, wherein the cable is tensioned by stretching a continuous outer cable. In constructing a bridge body in which the closing portion is a side span, one end of the corrugated steel web connection body is connected to the tip of the overhanging bridge body and the other end is placed on the abutment, and the lower slab concrete The method of claim 1, wherein the corrugated steel sheet web PC bridge closing portion is cast. 3. The corrugation according to claim 2, wherein the lower floor slab concrete is cast sequentially from the overhanging bridge body side to relieve a local stress in a suddenly changing section between the concrete and the corrugated steel web link. Construction method of steel web PC bridge closure. The method according to claim 2 or 3, wherein the placing of the upper floor slab concrete is sequentially performed from the side of the overhanging bridge body. In constructing a bridge body in which the closing portion is a center span, the both ends of the corrugated steel web connection body are respectively connected to the tips of the overhanging bridge body, and the lower deck slab concrete is cast. The method for constructing a closed section of a corrugated steel web PC bridge according to claim 1. 6. The method according to claim 5, wherein the lower floor slab concrete is cast sequentially from one or both of the overhanging bridge bodies to relieve a local stress in a suddenly changing section between the concrete and the corrugated steel web web. The construction method of the closed section of the corrugated steel web PC bridge described in the above. The construction method of a corrugated steel web PC bridge closure according to claim 5 or 6, wherein the placing of the upper deck slab concrete is sequentially performed from one or both of the overhanging bridge bodies. A working girder is used for erection of the corrugated steel sheet web, and after placing the lower slab concrete, the working girder is removed to give a compressive stress degree to the lower slab concrete, and the tensile stress of the lower slab concrete is reduced. The method according to any one of claims 1 to 7, wherein the degree of relaxation is reduced.

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