JP4056540B2 - Bridge girder construction method - Google Patents

Description

  The present invention relates to a method for constructing a bridge girder used as a road bridge, a railway bridge, a pedestrian bridge, and the like, and more particularly to a method for constructing a bridge girder made of concrete or a composite structure of a concrete and a steel member.

  Bridge girder made of concrete, especially prestressed concrete, is widespread. Various cross-sectional shapes such as box-shaped cross section, T-shaped cross section, U-shaped cross section, etc. Is built according to. In addition, a bridge girder using a steel member for a part of a cross section is often used. In particular, there is a bridge girder having a box-shaped cross section and using a steel plate for a web. In such a bridge girder, the upper floor slab is made of concrete to support a wheel load acting on a wide area of the road surface, and the weight of the bridge girder can be reduced by using a steel material for the web. Patent Document 1 proposes a structure in which a steel web is divided in an axial direction of a bridge girder (hereinafter referred to as a bridge axis direction).

  In this bridge girder, the steel web connecting the concrete upper floor slab and the lower floor slab is divided into a predetermined length in the bridge axis direction, and each steel web is separated from the middle in the height direction. The width in the direction of the bridge axis is gradually enlarged as approaching the upper side to be joined to and the lower side to be joined to the lower floor slab. That is, each of the divided steel webs has a drum shape or a butterfly shape. Each of these steel webs is precast segmented to form a box-shaped cross-section member, which is connected in the bridge axis direction on the site to construct a bridge girder.

Various methods have also been proposed in which a bridge girder is manufactured as a precast segment as described above, and connected in the field to construct a bridge girder. For example, a support is constructed at the girder installation position, and the precast segment is installed on this. There is a method of arranging and connecting. In addition, when it is difficult to construct a support work, or when it is not economical, a so-called cantilever construction method is adopted in which the precast segments are sequentially projected from the pier while maintaining the balance of the falling moment on both sides.
JP 2002-220812 A

However, there is a demand for an economical erection method in which a so-called medium-scale bridge, that is, a bridge having a span length of about 30 m to 70 m, is erected with a bridge girder using concrete as described above, and the construction cost is high.
In the construction method that constructs a support work over the entire span, if the pier is high, a lot of work and costs are required to construct the support work, and it is often difficult to construct a support work on steep terrain such as a valley. In the cantilever construction method in which the girders are sequentially projected from the pier to both sides, the precast segments produced by dividing are sequentially joined one by one, and the construction period tends to be long. In addition, it is difficult to adopt with a bridge girder between single diameters.
In addition, there is a method of temporarily installing a girder or truss for erection and connecting a bridge girder by supporting a precast segment to this, but it requires a lot of expenses for temporary girder or truss construction and is not a continuous multi-span bridge girder. And not economically advantageous.

  The present invention has been made in view of the circumstances as described above, and its purpose is to provide a method for efficiently and economically installing a bridge girder made of concrete or a bridge girder made of a composite structure of concrete and a steel member. It is to be.

In order to solve the above-mentioned problems, the invention according to claim 1 is a method for erection of a bridge girder having a box-shaped cross section by using an upper floor slab and a lower floor slab made of concrete, and a steel member that connects them vertically. A member including at least the lower floor slab of the upper floor slab, the lower floor slab, and the steel member constituting the bridge girder, and a step of stretching a tension material between two abutments Forming a plurality of precast segments divided into a predetermined length; and supporting the precast segment on the tendon so that the tendon passes inside a box-shaped region using the precast segment. A step of arranging a plurality of precast segments along the tendon at a position substantially coincident with a height of the bridge girder, and connecting the plurality of precast segments arranged in the bridge axis direction. And supporting both ends of the bridge girder to which the precast segment is connected, fixing the tension material to the end of the bridge girder, and introducing prestress into the bridge girder by the tension force introduced into the tension material The precast segment is suspended from the tension material by a suspension support member raised upward from the lower floor slab, and the precast segment is used as a tension material according to the dimensions of the suspension support member. When supporting along, it is arranged so that the height of the bridge girder is almost adjusted, and all or a part of the steel member and the upper floor slab is formed by a predetermined cast on the tension member. Provided is a bridge girder erection method which is formed so as to surround a range where the tendon is stretched after being supported in position .

In this method, a tension member, that is, a cable is stretched between the abutment or the pier, so that the precast segment can be supported by the cable and arranged in the direction of the bridge axis. Further, the precast segment can be supported by the cable near the abutment or the pier and moved along the cable to be arranged at a predetermined position. Therefore, the construction can be performed without using a large erection machine or equipment such as a support, a cable crane, a large crane, or the like.

  In addition, in this method, the stretched cable is in a suspended state. By adjusting and arranging the position of the precast segment on the cable in the height direction, the segments supported by the cable are connected to each other in a predetermined manner. Longitudinal linear bridge girder can be constructed.

  Furthermore, after the precast segments are connected, both ends of the bridge girder can be supported, the cable can be fixed to the end of the bridge girder, and prestress can be introduced into the bridge girder by the tension force introduced into the cable. As described above, the cable used for transporting, arranging and connecting the precast segments to a predetermined position can be used as a tension material for introducing prestress, and temporary costs can be reduced. Further, by fixing the cable to the bridge girder itself, a so-called self-contained structure is obtained, and the cable tension does not act on the abutment or the pier, and a stable structure can be obtained.

  A bridge girder having a box-shaped cross section that uses a steel member for the web portion maintains high rigidity and reduces weight. Thereby, the bridge girder having a box-shaped cross section having a steel web does not become excessively tensioned even when suspended and supported by a tension member stretched, and can be efficiently installed by the method of the present invention.

Further, since the lower floor slab is suspended from the cable by the suspension support member , it can be conveyed along the cable to a predetermined position, and the precast segment is supported at a predetermined height by adjusting the suspension support member. It becomes easy.
The cable is surrounded by a steel member and an upper floor slab that are formed after the precast segment is supported at a predetermined position, and an effective prestress can be introduced into the bridge girder by tension.

The invention according to claim 2 is the bridge girder construction method according to claim 1 , wherein the steel member is separated for each of the plurality of precast segments.

  In this method, since the steel member is separated for each precast segment, the step of joining the steel member, for example, a steel web in the bridge axis direction can be omitted. And if the steel member is divided and independent in the bridge axis direction in this way, the handling is easy and the displacement of the floor slab when pre-stress is introduced is less restricted, and the floor slab is effectively subjected to compressive stress. be introduced.

The invention according to claim 3 includes a floor slab made of concrete and a stiffening girder protruding downward from a side edge of the floor slab or a side plate raised up from the side edge of the floor slab. A method of laying a bridge girder having a step of stretching a tension member between two abutments, a step of forming a plurality of precast segments obtained by dividing the bridge girder into a predetermined length in a bridge axis direction, and the precast segment A step of supporting the tendon and arranging a plurality of precast segments along the tendon at a position substantially coincident with a height of the bridge girder, and connecting the arranged precast segments in the bridge axis direction And supporting both ends of the bridge girder to which the precast segment is connected, fixing the tendon to the end of the bridge girder, and by the tension force introduced into the tendon A step of introducing prestress into the girders, and a support member is attached to the outer surface of the stiffening girder portion or the side plate portion on both sides of the precast segment, and the two supporting members are stretched When the precast segments are arranged on the tendon by adjusting the mounting position of the support member, the precast segments are suspended and supported between the two tendons. It is intended to provide a bridge girder construction method that is arranged at almost the height of the bridge girder.

The invention according to claim 4 is the bridge girder construction method according to claim 1, claim 2 or claim 3 , wherein a lower chord member is stretched under the bridge girder, and the lower chord member and the bridge girder are A columnar external support member connected in the vertical direction is provided, and after connecting the precast segments, the tension of the lower chord material is adjusted to set the height of the span portion of the bridge girder to a predetermined height. .

  In this method, the load acting on the bridge girder is shared by the lower chord material, and the load carrying capacity of the bridge girder increases, so that it is possible to construct a bridge girder with a longer span. In addition, the bridge girder can be installed by accurately setting the height of the span portion of the bridge girder, that is, the shape in the longitudinal direction.

The invention according to claim 5 is the bridge girder erection method according to claim 4 , wherein both ends of the lower chord member are fixed to both ends of the bridge girder in a state in which tension is adjusted.

  Prestress is effectively introduced into the bridge girder by fixing the lower chord material to both ends of the bridge girder as described above. Moreover, a large horizontal force does not act on the abutment or the pier, and the abutment and the pier have a stable structure.

  As described above, according to the erection method of the present invention, the precast segment can be supported by the cable, conveyed to a predetermined position on the cable, and arranged. And since these precast segments can be connected and used as a bridge girder, a bridge girder can be constructed without requiring support construction or large heavy machinery. In addition, the cable for supporting the precast segment can be used as a tensioning material for introducing prestress into the bridge girder after connecting the precast segment. Is possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic side view of a bridge girder that can be constructed using cables stretched in the same manner as the construction method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view.
This bridge girder 1 is simply supported between two abutments 2 and 3 via supports 4 and 5,
The upper floor slab 11 and the lower floor slab 12 made of concrete are arranged in two rows along the bridge axis direction,
It consists of a steel web 13 that connects the upper floor slab 11 and the lower floor slab 12 up and down, and has a box-shaped cross section. Further, a cable 14 which is a tension agent is arranged in a box-shaped cross section surrounded by these, and prestress is introduced into the upper floor slab 11 and the lower floor slab 12 by this cable 14.

The upper floor slab 11 has a predetermined width and is continuous in the bridge axis direction, on which a road surface is formed. The road deck 11 is formed of reinforced concrete, and prestress is introduced in a direction perpendicular to the bridge axis as necessary.
The portion connected to the steel web of the upper floor slab, that is, the central portion 11a of the upper floor slab is formed of a plate-like member having a uniform thickness in the direction of the bridge axis. The steel web 13 is joined by embedding. A portion 11b projecting from the joint with the steel web 13 is formed of a concrete rib 11c projecting in a direction perpendicular to the bridge axis, and a substantially equal thickness plate member 11d integrated therewith. The vicinity of the tip of the rib 11c is supported by an oblique support member 15 having a lower end joined to a side edge of the lower floor slab 12.
On the other hand, the lower floor slab 12 is a concrete plate-like member joined to both of the steel webs 13 arranged in two rows, and is joined by embedding the vicinity of the lower edge of the steel web 13 in the concrete.

  The steel web 13 connects the upper floor slab 11 and the lower floor slab 12 and is an array of a plurality of steel plates divided in the bridge axis direction. Each steel plate has the smallest width at an intermediate position between the upper side and the lower side, and the width is linearly enlarged toward the upper side or the lower side, thus forming a drum shape. The steel drum shape reduces the weight and effectively resists the tensile and compressive forces in the oblique direction when a shearing force acts on the bridge girder. And the concrete rib 13b is formed so that it may closely_contact | adhere to a side surface, and it bears the compressive force of a diagonal direction, and prevents buckling. Moreover, since it arrange | positions separately for every precast segment, it is not necessary to connect between webs. Further, when prestress is introduced, deformation of the upper floor slab 11 and the lower floor slab 12 in the direction of the bridge axis is rarely restricted, and the prestress is effectively introduced.

  The upper floor slab 11 and the lower floor slab 12 are connected by the steel web 13 and are joined together at the both ends of the bridge girder 1 by the end cross beams 16 and 17. The end cross beams 16 and 17 are supported on the abutments 2 and 3 by the supports 4 and 5.

  The cable 14 is fixed to the end cross beams 16 and 17 in a state where tension is introduced. The upper floor slab 11, the lower floor slab 12, and the steel web 13 are stretched in a convex shape on the inner side surrounded by the box shape, and are attached to the upper floor slab 11 via the support member 18 at a predetermined position. It gives the upward force. That is, the cable 14 is arranged outside a concrete member called a so-called outer cable, and a cable having a rust-proof coating layer formed on the outside of a high-strength steel wire is used.

Next, an example of a method for constructing the bridge girder shown in FIGS. 1 and 2 will be described as a reference example .
First, abutments 2 and 3 are constructed on both sides of the position where the bridge girder is constructed. The abutments 2 and 3 are firmly fixed to the ground or the rock by the earth anchors 6 and 7 so as to resist a large horizontal force. Then, as shown in FIG. 3, end blocks 16 ′ and 17 ′ serving as end cross beams are formed on these abutments 2 and 3 via supports 4 and 5, and temporarily fixed to the abutments 2 and 3. . The end blocks 16 'and 17' are preferably formed by placing concrete on site,
It may be formed of precast concrete. End block 16 ',
For example, as shown in FIG. 3, the temporary fixing block 17 '
, 20 are inserted and tightened with a temporarily fixed steel material 21 in the vertical direction.

Thereafter, the cable 14 is stretched between the end blocks 16 'and 17'. The cable 14 to be stretched here is inserted into a sheath embedded in the end blocks 16 ′ and 17 ′, and the extension cable 22 is added with a coupler to a fixing body in which both ends are crimped to steel strands. Established on Abutment 2. As a result, the reaction force acting from the cable 14 during installation is borne on the earth anchor 6 via the abutment 2 so that no large reaction force acts on the end block 16 '. A nut 23 is screwed onto the fixing body, and the cable 14 can be fixed by applying a reaction force to the end blocks 16 'and 17' in the completed system.

On the other hand, in a factory or a girder production yard, a plurality of precast segments divided by a cross section perpendicular to the bridge axis direction are produced. 4 is a front view of the precast segment 1a constituting the bridge girder, and FIG. 5 is a perspective view obliquely from below.
The precast segment 1a used for manufacturing the bridge girder 1 is a central portion 1 of the upper floor slab.
1a, ie, an upper floor slab between two webs, a steel web 13, a rib 11c for supporting an overhanging portion 11b of the upper floor slab 11, and a slant that supports the vicinity of the tip of the rib 11c from the side edge of the lower floor slab. A main part is constituted by the support member 15.

  In the vicinity of the upper edge of the steel web 13, a plurality of stud gibbles 13 a are planted, and the concrete of the upper floor slab is cast so as to be embedded and firmly integrated with the steel web 13. Further, a concrete member that forms both end portions 12 a of the lower floor slab 12 is formed at the lower end of the steel web 13. Similar to the upper floor slab 11, both end portions 12 a of the lower floor slab are formed by casting concrete so as to embed the stud gibber 13 a planted in the steel web 13. And it arrange | positions so that the reinforcing bar 12b may be protruded in the center part side of the lower floor slab 12, and it shall aim at integration with the concrete laid in the field.

  One end of the rib 11c extends laterally in the direction perpendicular to the bridge axis from the vicinity of the joint between the upper floor slab 11a and the steel web 13, and is provided at one location with respect to one precast segment. One end of the oblique support member 15 is joined to the lower surface near the tip of the rib 11c, and the other end of the oblique support member 15 is attached to the end portion 12a of the lower floor slab that is integrally formed with the steel web 13. It is assumed that the load acting on the overhanging portion 11b of the upper floor slab after the bridge girder is installed is supported from below through the rib 11c.

The support member 18 is provided to support the precast segment 1a on the cable 14, and is a U-shaped member protruding downward from the lower surface of the upper floor slab 11a. And the two latching | locking parts 18a provided in the lower end part are each latched to the two cables 14, and the precast segment 1a is supported on the cable 14. FIG. The support member 18 is formed of mold steel or the like, and one or two are provided in one precast segment.
This support member 18 is a precast segment used in the central part of the span of the bridge girder 1.
A thing with a large height is attached, and a thing with a small height is attached to the precast segment used near the end of the bridge girder 1. That is, when each precast segment 1a is supported on the cable 14 by these support members 18, the upper surface of each precast segment shall be arranged flatly along the vertical alignment at the time of completion.
This support member 18 maintains the function of connecting the cable and the bridge girder and transmitting the force even after the bridge girder is completed, but in addition to this, in order to stabilize the precast segment during erection, The support member may be used only during installation.

As shown in FIG. 6, the precast segment 1 a formed as described above is lifted by, for example, a crane 24 and is supported on the cable 14 via the support member 18 in the vicinity of the abutment. Then, it travels on the cable 14 and is transported to a predetermined position, and temporarily fixed at a predetermined position on the cable 14. Such operations are sequentially repeated, and a plurality of precast segments 1a are arranged in almost the entire area of the bridge girder to be installed. At this time, the dimension of the support member 18 is set so that the upper surface of the upper floor slab of each precast segment arranged is flat at a predetermined height. Further, the position of the precast segment in the height direction can be adjusted by adjusting the tension of the cable 14.

After all the precast segments 1a are arranged at predetermined positions on the cable 14, between the upper floor slabs 11a of adjacent precast segments 1a, between the upper floor slab 11a and the end blocks 16 'and 17', Filled concrete is placed between the end portions 12a of the lower floor slab and between the end portion 12a of the lower floor slab and the end blocks 16 'and 17' to connect each other.
In addition, the joining between precast segments can also be joined with an adhesive, when the joining surface of each precast segment is formed so that it may correspond exactly.

  Next, the concrete is placed between the concrete members 12 a respectively joined to the concrete at the center of the lower floor slab 12, that is, the lower end of the steel web 13. At this time, the formwork is supported by the concrete members 12a at both ends of the lower floor slab already formed, and concrete is placed so as to embed the reinforcing bars 12b protruding from the concrete members 12a. By forming the lower floor slab 12 in this way, a box-shaped cross section closed by the upper floor slab 11a, the lower floor slab 12, and the two steel webs 13 is obtained, and has a large rigidity.

Thereafter, axial prestress is introduced into the bridge girder 1 by the tension of the cable 14.
The cable 14 is fixed to the end block, that is, the end cross beams 16 and 17 in a state where a predetermined tension force is introduced, and the reaction force of the cable 14 is applied to the bridge beam. Then, the extension cable 22 connected to the cable 14 is removed, and the temporarily fixed blocks 19 and 20 and the temporarily fixed steel material 21 that have temporarily fixed the end blocks 16 ′ and 17 ′ are removed. As a result, the reaction force of the cable 14 shifts from the abutments 2 and 3 to the end cross beams 16 and 17 and is transmitted from the end cross beams 16 and 17 to the bridge beam 1 as an axial force. As a result, the box girder is simply supported at both ends. That is, the tensile force acting on the cable 14 and the compressive force acting on the bridge girder 1 are offset, and the structure is converted into a so-called self-contained structure system in which no horizontal force acts on the abutments 2 and 3.

  Furthermore, as shown in FIG. 7, the overhanging portion 11b of the upper floor slab lays the concrete panels 25 into which the prestress is introduced by the pretensioning method on the ribs 11c, and assembles the reinforcing bars thereon. And this concrete panel 25 is used as a formwork, and concrete is poured so that it may become one. That is, the concrete panel into which the prestress is introduced functions as a mold and becomes a part of the upper floor slab 11. Thereby, the process of installing and removing the formwork for placing concrete can be omitted, and the construction period can be shortened.

In the bridge girder, prestress is introduced into the bridge girder 1 only by the cable 14 stretched to support the precast segment during erection, but the cross section becomes a box shape after the precast segment is connected. An additional cable can be stretched on the inside of the raised part to introduce tension and introduce sufficient prestress.
Further, the additional cable may be arranged below the bridge girder having a box-shaped cross section as shown in FIG. Both ends of the cable 26 are fixed to the end cross beams 16 and 17 and the shape of the cable 26 is constrained by an external support member 27 attached to the lower surface of the bridge girder. It is intended to transmit the power of.

  By introducing tension in such an additional cable, the central part of the span of the bridge girder is pushed upward. Accordingly, the span portion of the bridge girder is accurately set to a predetermined height by adjusting the tension.

Note that the cable 26 may be disposed first together with the cable 14 supporting the precast segment 1a, or may be disposed at a predetermined position after the precast segment 1a is connected. And tension is introduced after the precast segments are connected.
The cable 26 may be a cable in which a steel wire is coated similarly to a cable arranged inside a box-shaped section. Moreover, it can also be set as the thin concrete board which included the cable.

Next, a construction method of a bridge girder which is an embodiment of the invention according to the present application will be described.
FIG. 9 is a schematic side view showing an example of a bridge girder that can be installed by this method.
FIG. 10 is a cross-sectional view.
This bridge girder 31 is simply supported between the two abutments 2 and 3 in the same manner as the bridge girder 1 shown in FIG. 1, and is composed of an upper floor slab 41 made of concrete placed on site and mainly precast concrete. The lower floor slab 42 formed, the steel web 43 that connects them up and down, and the cable 44 that is disposed within the range surrounded by these and introduces prestress into the upper floor slab 41 and the lower floor slab 42 are mainly used. The part is formed.

In this bridge girder, the steel web 43 is formed from a rectangular steel plate and is divided in the bridge axis direction,
They are arranged in two rows at a predetermined interval. These steel plates may be bonded by embedding the vicinity of the upper edge and the vicinity of the lower edge in the concrete of the upper floor slab 41 and the lower floor slab 42, or providing horizontal flanges along the upper edge and the lower edge. In addition, concrete may be placed so as to embed a stopper member such as a stud gibber attached to the flange.

The bridge girder 31 can be erected as follows.
Similarly to the bridge girder 1 shown in FIG. 1, the abutments 2 and 3 are constructed, and the end blocks 46 and 47 are temporarily fixed on the abutments 2 and 3 via the supports 4 and 5. Then, the cable 44 is stretched between the end blocks 46 and 47.

  On the other hand, the precast segment 31a manufactured in the factory or the girder yard is suspended and supported by a concrete lower floor slab 42, a steel web 43 raised on this, and a cable 44, as shown in FIG. It is assumed that the main part is formed with the suspension support member 45 for causing the above. Further, it is possible to attach the suspension support member 45 to the lower floor slab 42 without attaching the steel plate to be the steel web 43, and the steel web 43 may be attached after the precast segments are connected in the field.

  The precast segment 31a is carried into the site, and is lifted by a crane 48 or the like as shown in FIG. And it conveys along the cable 44 and arranges the several precast segment 31a in a predetermined position sequentially. At this time, the lower edge of each precast segment 31a is supported so as to substantially coincide with the height of the lower surface of the bridge girder, depending on the dimensions of the suspension support member 45 and the like. Thereafter, the interstitial concrete is placed between the lower floor slabs 42 adjacent to each other and between the lower floor slab 42 and the end blocks 46 and 47 to be connected. And prestress is introduce | transduced into the lower floor slab 12 as needed. This pre-stress may be one in which a tension material is inserted into a duct previously formed in the lower floor slab 42 of the precast segment and introduced by this tension material, or an outer cable is connected along the lower floor slab. You may arrange.

Next, a form for forming the upper floor slab 41 is assembled on the connected lower floor slab 42, and concrete is placed to form an upper floor slab.
When the upper floor slab 41 and the lower floor slab 42 are formed so as to be continuous between the two end blocks 46 and 47, the cable 44 fixed to the abutment is connected to the end blocks 46 and 47, that is, the bridge girder formed. Fixing is performed at the cross beam portion, and the reaction force of the cable 44 is applied to the bridge beam 31. As a result, prestress is further introduced into the bridge girder 31 and can resist the live load acting on the bridge girder.

In the above construction method, the concrete of the upper floor slab 41 is placed after the lower floor slab portion of the precast segment is connected in the direction of the bridge axis, but the formwork is installed in a state before the lower floor slab is connected. Then, the concrete of the upper floor slab may be cast and the lower floor slab of each precast segment may be connected.
In addition, arrange an additional cable inside the bridge girder in a box shape or under the girder like the bridge girder shown in Fig. 8, and introduce tension after the lower floor slab and upper floor slab are connected. It can be fixed at both ends of the bridge girder.

FIG. 13 is a schematic side view showing another example of a bridge girder that can be constructed by the erection method according to the present invention, and FIG. 14 is a sectional view.
This bridge girder 51 is made of concrete in its entire cross section, and includes a floor slab 61 that forms a road surface, a stiffening girder portion 62 that protrudes downward from a side edge of the floor slab 61, and a side edge of the floor slab. And a side plate portion 63 raised upward. 1 is simply supported between the two abutments 2 and 3 in the same manner as the bridge girder shown in FIG. 1, and is prestressed by cables 64 fixed to both ends of the bridge girder and stretched outside the side plate portion 63. Has been introduced. A lower chord member 68 is provided below the bridge girder 51 so as to hang downward from both ends, and supports the lower end of the external support member 69 protruding downward from the lower surface of the bridge girder 51. ing.

  Vertical ribs 70 are provided outside the side plate portion 63 and the stiffening girder portion 62 at positions spaced apart in the axial direction of the bridge girder 51, and the outer side surfaces are substantially vertical. A support member 65 is attached to a predetermined height of the vertical surface, the support member 65 is locked to the cable 64, and a load in the vertical direction is transmitted from the bridge girder 51 to the cable 64.

  The side plate part 63 is formed of concrete integrated with the floor slab 61 and the stiffening girder part 62 and functions as a part of the bridge girder 51 and is used as a rail. And the circular through-hole 63a is provided in the axial direction of the bridge girder 51 at predetermined intervals, and the weight is reduced.

  The external support member 69 is made of a steel pipe, and the lower end thereof is connected to a concrete plate 68 a constituting the lower chord material 68. The lower chord material 68 is mainly composed of a thin concrete plate 68a continuous between both ends of the bridge girder 51 and a cable 68b fitted in a groove provided on the lower surface of the concrete plate. Stress has been introduced.

The bridge girder 51 can be erected as follows.
As with the bridge girder shown in FIG. 1, end blocks 66 and 67 are formed on the abutments 2 and 3, and a cable 64 is stretched between them. On the other hand, the precast segment 51a constituting the bridge girder 51 is manufactured in a shape in which a bridge girder including a floor slab 61, a stiffening girder part 62, and a side plate part 63 is divided into a predetermined length in the axial direction. Support members 65 are attached to both sides of the precast segment 51a, locked to the two cables 64 stretched, and supported by being suspended between the two cables. And as shown in FIG. 15, it slides on the cable 64 and conveys to a predetermined position. In this manner, the plurality of precast segments are suspended and supported, conveyed, and arranged at predetermined positions. At this time, the position where the support member 65 is attached is adjusted for each precast segment, and when arranged on the cable 64, each precast segment is positioned at a height at which the bridge beam is constructed. Yes.

  In addition, although the precast segment 51a conveyed on the cable 64 may be conveyed one by one, as shown in FIG. 15, two can be temporarily joined on the cable 64 and these can be conveyed as a unit. . Thereby, the precast segment 51a can be conveyed in a stable state. Moreover, it is desirable to attach the steel pipe used as the external support member 69 to the lower surface of a predetermined position by the precast segment to which the external support member 69 is connected before conveyance.

  The precast segments 51a arranged on the cable 64 are connected by filling between the adjacent precast segments and between the precast segments 51a and the end blocks 66, 67 by filling concrete. The cable 64 fixed to the abutments 2 and 3 is fixed by the end blocks 66 and 67, and the reaction force of the cable 64 is applied to the bridge girder 51 to introduce prestress into the bridge girder 51.

  Further, a cable 68b constituting the lower chord material 68 is stretched below the bridge girder 51, and precast concrete plates 68a are arranged on the cable, and these are connected to form the lower chord material 68. However, as shown in FIG. 15, the precast concrete board 68a is not connected to the ends of the bridge girders at both ends, and allows a large deformation in the axial direction of the lower chord material. Then, the height of the lower chord material 68 is adjusted by adjusting the tension of the cable 68b and joined to the lower end of the external support member 69, and the lower chord material 68 bears the weight of the bridge girder 51 and a part of the loaded load. A compressive force is introduced into the external support member 69. As a result, the bridge girder can be pushed upward, and the height of the bridge girder can be adjusted to an accurate position. Both ends of the lower chord material are connected after the adjustment of the tension of the lower chord material is completed.

  The bridge girder 51 has a lower chord member 68. However, only the bridge girder 51 formed by the concrete floor slab 61, the stiffening girder portion 62, and the side plate portion 63 supports the load. A structure that does not use the material 68 can also be employed.

It is a schematic side view of the bridge girder which can be constructed | assembled using a cable similarly to the construction method which is one Embodiment of this invention. It is sectional drawing of the bridge girder shown in FIG. It is a schematic side view which shows the structure of the bridge girder edge part in construction of the bridge girder shown in FIG. It is a front view of the precast segment which comprises the bridge girder shown in FIG. It is a perspective view from diagonally downward of the precast segment which comprises the bridge girder shown in FIG. It is the schematic which shows the construction method of the bridge girder shown in FIG. It is a schematic perspective view which shows the method of forming the upper floor slab of the bridge girder shown in FIG. It is a schematic side view which shows the example of the other bridge girder which can be constructed using the same construction method as the bridge girder shown in FIG. It is a schematic side view of the bridge girder which can be constructed | assembled by the construction method which is embodiment of this invention. It is sectional drawing of the bridge girder shown in FIG. It is a perspective view of the precast segment which comprises the bridge girder shown in FIG. It is the schematic which shows the construction method of the bridge girder shown in FIG. It is a schematic side view of the bridge girder which can be constructed | assembled by the construction method which is other embodiment of this invention. It is sectional drawing of the bridge girder shown in FIG. It is the schematic which shows the construction method of the bridge girder shown in FIG.

Explanation of symbols

1: bridge girder, 1a precast segment, 2, 3: abutment, 4, 5: support,
6, 7: Earth anchor,
11: Upper floor slab, 11a: Center part of upper floor slab, 11b: Overhanging part of upper floor slab, 11c: Rib, 11d: Concrete placed on site, 12: Lower floor slab, 12a: Concrete at the end of lower floor slab Member, 12b: Reinforcing bar, 13: Steel web, 13a: Stud gibber, 13b: Concrete rib, 14: Cable (tension material), 15: Diagonal support member, 16, 17: End cross beam, 16 ', 17' : End block, 18: support member, 18a: locking portion, 19, 20: temporary fixing block,
21: Temporarily fixed steel material, 22: Extension cable, 23: Nut, 24: Crane,
25: Concrete panel, 26: Lower chord material, 27: External support member,
31: Bridge girder, 31a: Precast segment,
41: Upper floor slab, 42: Lower floor slab, 43: Steel web, 44: Cable (tension material), 45: Suspension support member, 46, 47: End block, 48: Crane,
51: Bridge girder, 51a: Precast segment,
61: Floor slab, 62: Stiffening girder part, 63: Side plate part, 63a: Through hole, 64: Cable (tension material), 65: Support member, 66, 67: End block, 68: Lower chord material, 68a: Concrete plate, 68b: Cable, 69: External support member, 70: Vertical rib

Claims (5)

A method for erection of a bridge girder having a box-shaped cross section by means of an upper floor slab and a lower floor slab made of concrete and a steel member that connects them up and down,
Stretching the tension material between the two abutments,
Forming a plurality of precast segments obtained by dividing a member including at least the lower floor slab of the upper floor slab, the lower floor slab, and the steel member constituting the bridge girder into a predetermined length in a bridge axis direction;
The precast segment is supported by the tendon so that the tendon passes through the inside of the box-shaped region using the precast segment, and a plurality of precast segments are installed along the tendon. Arranging at a position substantially coincident with the height to be
Connecting a plurality of precast segments arranged in the direction of the bridge axis;
Supporting both ends of the bridge girder to which the precast segment is connected, fixing the tendon to the end of the bridge girder, and introducing prestress to the bridge girder by the tension force introduced into the tendon. Including
The precast segment is suspended from the tendon by a suspension support member raised upward from the lower floor slab,
According to the dimensions of the suspension support member, when supporting the precast segment along the tension material, it is arranged so as to be adjusted to the height at which the bridge girder is constructed.
All or part of the steel member and the upper floor slab are formed so as to surround a range in which the tension material is stretched after the precast cast segment is supported at a predetermined position on the tension material. A construction method of bridge girder characterized by 2. The bridge girder construction method according to claim 1, wherein the steel member is separated for each of the plurality of precast segments. A bridge girder erection method comprising a concrete floor slab and a stiffening girder protruding downward from a side edge of the floor slab or a side plate raised upward from the side edge of the floor slab. ,
  Stretching the tension material between the two abutments,
  Forming a plurality of precast segments obtained by dividing the bridge girder into a predetermined length in the bridge axis direction;
  Supporting the precast segment on the tendon, and arranging a plurality of precast segments along the tendon at a position substantially coincident with the height of the bridge girder;
  Connecting a plurality of precast segments arranged in the direction of the bridge axis;
  Supporting both ends of the bridge girder to which the precast segment is connected, fixing the tendon to the end of the bridge girder, and introducing prestress to the bridge girder by the tension force introduced into the tendon. Including
  A support member is attached to the outer surface of the stiffening girder part or the side plate part on both sides of the precast segment,
  The supporting member is respectively engaged with the two tension members stretched, and the precast segment is suspended and supported between the two tension members,
  A bridge girder laying method characterized in that, when the precast segments are arranged on the tendon by adjusting the mounting position of the support member, the bridge girder is arranged at a height at which the bridge girder is erected. A lower chord member is stretched under the bridge girder, and a columnar external support member that connects the lower chord member and the bridge girder in the vertical direction is provided.
After connecting the precast segments, claim 1, characterized in that to set the height of the span portion of該橋digit at a predetermined height by adjusting the tension of the lower chord, claim 2 or claim 3 erection method of bridge girder described. The bridge girder construction method according to claim 4 , wherein both ends of the lower chord member are fixed to both ends of the bridge girder in a state in which tension is adjusted.

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