JP2006009449A - Truss panel girder and precast truss panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a truss panel girder which is available as a girder member of a bridge, a slab, etc., achieves thinning and lightweight of the girder member while ensuring necessary strength as the girder member, drastically improves construction efficiency, and contributes to shortening of a construction period and cost reduction, and to provide a precast truss panel. <P>SOLUTION: A panel constituting a web 1 of a box girder bridge or the like is formed of the truss-shaped precast truss panel 10 consisting of a frame 11 made of high-strength concrete A in the class of 150 N/mm<SP>2</SP>, and diagonal members 12. If necessary, the truss member to which a tensile force is applied, is reinforced by prestressing the same according to a pretension system or the like by using a prestressing steel 13. Then the panels 10 thus formed are connected together by mechanical shearing keys 14 or the like, and prestress is introduced to the panels in a bridge axial direction according to a post-tension system to unitarily connect the panels together as a truss panel web 1, followed by constructing an upper floor slab 2 by placing cast-in-place concrete on the truss panel web, to thereby construct the main girder. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a truss panel girder used for a girder member of a concrete structure such as a bridge or a slab, and a precast truss panel used for the truss panel girder, and particularly prestressed concrete (PC) such as a road bridge and a railway bridge. Effectively applied to bridges.

  The conventional concrete bridge has the following problems. (A) Concrete girders are heavy and difficult to apply to long spans. Moreover, the burden given to a substructure and a foundation is large. (b) The cast-in-place method (rebar assembly → formwork assembly → concrete placement) is complicated and requires a work period. There are also environmental problems such as construction by-products. Therefore, conventionally, the following improvement / solution means has been adopted.

(1) Precast blocks for girders Precast blocks produced at factories and production yards are carried to the construction site and integrated with adhesion and prestress to construct the girders. Labor-saving (mechanization) and construction period can be shortened. Since concrete blocks are heavy, there are problems such as the need for appropriate equipment for transportation and installation.

(2) Composite structure with steel members Replace the web members of girders with corrugated steel plates and steel pipe trusses to reduce weight and save labor. Moreover, there exists a proposal which devised the shape of a web steel plate as a prior art (patent document 1). There are problems such as the cost of processing and manufacturing steel members, poor workability requiring field welding, and the need for rust prevention measures such as painting.

(3) Use of high-strength concrete Girder web members are precast panels made of high-strength concrete (28-day compression strength 100 to 180 N / mm ² ) to reduce weight and save labor during construction (Patent Document 2).
JP 2002-220812 A JP 2004-68341 A

  Even the conventional improvement / solution means described above have the following problems.

(1) Weight reduction of members Upper floor slabs are members that are directly loaded with live loads, and it is important to maintain soundness and safety against fatigue and uncertainties of loaded loads. difficult. If the web is made of a steel member, it greatly contributes to weight reduction, but there is a problem of durability, and the cost of rust prevention measures becomes a problem. Further, in Patent Document 2, the web member is a precast panel having a pretension structure, and high strength concrete is used to reduce the thickness and reduce the weight. However, the concrete web has a certain thickness for the following reason. Therefore, there is a limit to weight reduction by thinning. (a) Ensuring safety against compression failure, (b) Ensuring safety against lateral bending, and (c) Ensuring the necessary thickness to place the appropriate stirrup amount.

(2) Truss structure The truss structure is mechanically rational as a girder and can be reduced in weight, but because it has many components, it requires local reinforcement at the floor slab joint, etc. There are problems such as poor performance and high cost.

(3) Joining precast members In the precast segment structure, segment seams are essential to ensure the performance against bending and shearing as girders. Usually, segment blocks are manufactured by match casting. However, labor saving and simplification of equipment and management are desired.

(4) Precast member production cost The precast segment construction method can be performed in a short period of time because it can be performed in parallel with the segment production and installation work. Since the construction equipment costs are expensive, a certain scale of construction (bridge length) is required to reduce the construction costs.

  The present invention was made to solve the above problems, and in a girder member such as a bridge or a slab, it is possible to reduce the thickness and weight of the girder member while ensuring the necessary strength. Moreover, it is an object of the present invention to provide a truss panel girder and a precast truss panel capable of greatly improving the workability and shortening the construction period and reducing the cost.

  Invention of Claim 1 of this invention is a truss panel girder used for the girder member of a concrete structure, and is comprised from an outer periphery frame (frame) and the diagonal material arrange | positioned in this outer periphery frame, These outer periphery frames, A truss panel girder characterized in that a plurality of precast truss panels in which diagonal members are made of concrete are joined.

  The present invention is applied to concrete structures such as bridges, piers, pedestrian bridges, slabs and deck structures. A precast panel used for webs such as bridge girders and beams such as slabs is not a single-sided plate, but a truss-like panel, and a panel with a large opening made of square or rectangular frames and diagonal materials. It is intended to reduce weight. In the case of a bridge girder web, a plurality of precast truss panels standing in parallel to the bridge axis direction are continued in the bridge axis direction to form a straight truss panel girder (web). In the case of beams such as slabs, precast truss panels are arranged vertically and horizontally on a plane to form a lattice-shaped truss panel beam (beam) in plan view.

  According to a second aspect of the present invention, in the truss panel girder according to the first aspect, high-strength concrete is used for the concrete.

  According to a third aspect of the present invention, in the truss panel girder according to the first or second aspect, a prestress is introduced into a portion to be pulled.

The concrete may be a normal strength concrete, but it is preferable to use an ultra high strength concrete having a compressive strength of 100 to 180 N / mm ^{2 on} the 28th, for example, to reduce the thickness of the panel. In the case of a box girder bridge web, it is recommended to use 150 N / mm ² class ultra high strength concrete. The truss panel girder truss type can be, for example, Howtruss, Platte truss, Warren truss, etc. Introducing pre-stress to the truss member subjected to tension with PC steel and reinforcing it, combined with the use of ultra high strength concrete To further reduce the wall thickness. Since ultra-high strength concrete is superior in adhesion performance compared to ordinary strength concrete, it is preferable to introduce prestress by a pretension method so that efficient prestress can be introduced. Note that the present invention is not limited to this, and a post-tension method may be used. In this case, a sheath hole may be provided at the time of panel manufacture.

  According to a fourth aspect of the present invention, in the truss panel girder according to any one of the first to third aspects, the vertical members of the outer frame of the precast truss panel are joined by a shear key means. Truss panel girder characterized by

  The joints between panels are easier to control the accuracy than precast segment box girder bridges, so there is no need to produce a match cast system. Further, by using a mechanical shear key for the joining method, it is possible to save labor when manufacturing the panel. In addition, not only this but a concrete shear key can also be used.

  According to a fifth aspect of the present invention, in the truss panel girder according to any one of the first to fourth aspects, the upper chord material of the precast truss panel outer peripheral frame is integrated by a cast-in-place slab. It is a truss panel girder that is characteristic.

  A precast concrete slab can be used for the floor slab, but it is preferable to embed the truss panel girder by embedding the upper chord material of the truss panel girder in the cast-in-place floor slab. In the case of a box girder bridge, a lower floor slab is provided in the same manner, but a structure without a lower floor slab is also possible.

  The invention of claim 6 of the present invention is characterized in that in the truss panel girder according to any one of claims 1 to 5, prestress in the longitudinal direction of the girder is introduced by a cable (PC steel material). Truss panel girder.

  A pre-stress PC steel material is used to introduce prestress in the longitudinal direction of the girder, and a truss panel girder composed of a plurality of precast truss panels is integrally installed. In the case of a bridge girder, use the inner cable in the floor slab and the outer cable arranged along the floor slab.

  The invention of claim 7 of the present invention is a precast panel used for a girder member of a concrete structure, and is composed of an outer peripheral frame (a square or rectangular frame) and diagonal members arranged in the outer peripheral frame. It is a precast truss panel that the outer peripheral frame and the diagonal member are made of concrete.

The invention of claim 8 of the present invention is a precast panel used for a girder member of a concrete structure, and is composed of an outer peripheral frame (square or rectangular frame) and diagonal members arranged in the outer peripheral frame. The outer frame and diagonal are made of high-strength concrete (for example, ultra high-strength concrete with 28-day compressive strength of 100 to 180 N / mm ² ), and the diagonal or outer frame is pre-stressed with tension steel (PC steel) Is a precast truss panel that has been introduced.

  The above-mentioned precast panel is preferably standardized and commercialized into several types of dimensions and the like so that it can be used in an appropriate combination according to the applicable span length.

  With the above configuration, precast truss panels made of high-strength concrete frames and diagonal materials are manufactured at the factory or on-site production yard, and prestressing is applied to the truss members by pre-tensioning as necessary to reinforce them. Then, this is carried into the erection site and installed at the position of the box girder web or beam. (1) Panels are joined together with a mechanical shear key, etc. (2) A floor slab such as cast-in-place is installed on a continuous truss panel girder, and (3) The post-tension method is used in the longitudinal direction of the girder if necessary. By introducing pre-stress, bridge girders and slabs are built.

  Since the present invention is configured as described above, the following effects can be obtained.

  (1) By making the precast truss panel that constitutes the girder members such as bridges into a truss shape consisting of a frame and diagonal members, it is possible to reduce the weight of the girder members while ensuring the necessary strength. By using pre-stress by using ultra-high-strength concrete for the member, high shear resistance can be secured, so that the girder member can be made thinner. As a result, the weight of the girder member can be greatly reduced, and a significant reduction in construction cost can be expected.

  (2) The use of a concrete truss panel eliminates the need for costly manufacturing and processing of steel members compared to the composite structure of steel members, and saves rust prevention measures and maintenance costs. The complexity of welding and the like is eliminated, so that the workability can be improved, the work period can be shortened, and the cost can be reduced.

  (3) By using a precast truss panel consisting of a frame and diagonal materials, the web can greatly reduce the number of members that make up the truss, compared to the composite structure of steel pipe trusses, This also eliminates the need to reinforce the work, improving workability, shortening the construction period, and reducing costs.

  (4) By joining the frame and the precast truss panel made of diagonal material to form the truss panel girder, it is possible to continuously join the floor slab with the continuously integrated frame, and the local slab generated on the floor slab The stress can be reduced and the joint structure can be simplified.

  (5) If a mechanical shear key is used to join the precast truss panels, it is possible to rationalize and simplify the panel production and installation.

  (6) By pre-casting the truss members, the quality of the web can be improved, and the work of formwork and concrete placement for web construction on site can be omitted, saving labor and shortening the construction period. Cost can be reduced.

  (7) If the PC steel material of the truss member as the web shear reinforcement is a pre-tension method, the grout work becomes unnecessary compared with the post-tension method, and labor saving and improvement in durability can be expected.

  Hereinafter, the present invention will be described based on the illustrated embodiments. This embodiment is applied to a prestressed concrete (PC) bridge such as a road bridge or a railway bridge. FIG. 1 is a side view showing a basic structure of a bridge girder using a truss panel girder according to the present invention for a web. FIG. 2 is a perspective view showing an example of a PC box girder bridge using the truss panel girder of the present invention for a web. FIG. 3 is a side view showing an example of the truss format used in the present invention. 4 and 5 show an example of a panel joining key used in the present invention. FIG. 6 is a front view showing an example in which the truss panel girder according to the present invention is applied to a bridge girder. FIG. 7 is a front view showing an example of a bridge without a lower floor slab.

  As shown in FIG. 1, a truss-shaped precast truss panel 10 made of ultrahigh-strength concrete A is used for a web 1 having a bridge superstructure. The panel 10 includes a quadrangular frame 11 as an outer peripheral frame and a diagonal member 12 that is integrally disposed at diagonal positions of the frame 11. The upper and lower two sides and the left and right sides of the frame 11 constitute the upper and lower chord members 11a and the vertical member 11b, respectively. The shape of the frame 11 is basically a square having a side length of about 1 to 3 m, and the angle of the diagonal member 12 is 45 degrees, but may be a rectangle as necessary.

As the ultra high strength concrete A, for example, ultra high strength concrete (28-day compressive strength 100 to 180 N / mm ² ) having material specifications and performance described in Patent Document 2 can be used. Further, 150 N / mm ² class ultra high strength concrete is preferable.

  By adopting the truss structure, the members (frame 11 and diagonal 12) become members in which the axial force is dominant, and in particular for members on which compressive force acts, it is possible to make use of the performance of ultra-high strength concrete having high compressive strength. it can. Furthermore, if necessary, the member on which the tensile force acts is pretensioned by the PC steel material 13 to be reinforced. When pre-tensioning is introduced into a tensile material, adhesion of PC steel and concrete (the length necessary for fixing the PC steel material) becomes an issue, but ultra-high strength concrete has better adhesion performance than ordinary strength concrete. In addition, the ultra-high-strength concrete of Patent Document 2 has a small amount of self-shrinkage, so that it is possible to introduce prestress efficiently. Note that the present invention is not limited to such a pre-tension method, and a post-tension method may be used if a sheath hole is provided at the time of panel manufacture.

  Such a precast truss panel 10 is placed upright so that the surface thereof is parallel to the bridge axis direction, and the vertical members 11b of the frame 11 are joined together by the joining key 14, and the truss panel girder, that is, the truss that is continuous in the bridge axis direction. A panel web 1 is formed. An upper floor slab 2 is cast in place on the upper chord member 11a of the truss panel web 1, the truss panel web 1 is integrated, a post-tension type PC steel material 15 is disposed, and prestress in the bridge axis direction is introduced.

  As the truss format of the truss panel web 1, a truss format as illustrated in FIG. 3 can be adopted. FIG. 3A shows a howtruss, in which a compressive force acts on the diagonal member 12 and a tensile force acts on the vertical member 11b against the shearing force acting on the truss girder. FIG. 3B shows a plat truss, where a tensile force acts on the diagonal member 12 and a compressive force acts on the vertical member 11b. FIG. 3C shows a warren truss, and compressive force and tensile force act alternately on the diagonal member 12 and the vertical member 11b. However, the present invention is not limited to this, and other truss formats can also be adopted. For example, the diagonal member 12 is preferably one in terms of weight reduction, but may be a double warren truss having two.

  For example, a mechanical shear key shown in FIG. 4 is used for the joining key 14 to save labor in panel manufacture. The mechanical shear key 14 is formed by embedding a male key 14a and a female key 14b in advance when manufacturing a panel, and fitting the protruding portion of the male key 14a into the female key 14b. . Not only the illustrated example but other mechanical shear keys may be used. In FIG. 1, the mechanical shear keys 14 are arranged above and below the frame 11, but the arrangement is not limited to this, and other arrangements may be used. Further, a multistage or corrugated concrete shear key 20 as shown in FIG. 5 may be used.

  In addition, the precast truss panel 10 is standardized and commercialized into several types of dimensions and the like, and can be used in appropriate combinations according to the applicable span length.

  When the truss panel web 1 composed of the precast truss panel 10 as described above is applied to a prestressed concrete bridge having a box girder structure shown in FIG. 2, construction is performed in the following procedure.

  (1) The precast truss panel 10 is manufactured in a factory or a field production yard, is carried into a construction place, and is installed at a position corresponding to the main girder web to form a truss panel web 1. The direction in which the panel 10 is arranged (the direction of the diagonal member 12) can be arbitrarily set according to the design (see FIG. 3).

  (2) After the upper floor slab 2 and the lower floor slab 3 are constructed by cast-in-place construction and integrated as a girder, pre-stress is introduced in the post-tension method in the bridge axis direction to construct the main girder. For the post-tension type PC steel material, the inner cable 4 and the outer cable 5 arranged on the floor slab can be used. The upper chord material portion that is continuous in the bridge axis direction of the truss panel web 1 is embedded in the upper floor slab 2, and the lower chord material portion is a thick wall portion that protrudes inward, and this portion is joined to the lower floor slab 3 via a reinforcing bar or the like. . As the bridge erection method, an overhang erection method, an extrusion erection method, a batch erection method, or the like can be used.

  FIG. 2 shows a case where the precast truss panel 10 is used as a web in the bridge axis direction, but it can also be used as a cross beam member in a direction perpendicular to the bridge axis. FIG. 6 shows an example in which the precast truss panel 10 is applied to the cross beam 6, and the two panels 10 are joined by a mechanical shear key 14 to form a short truss panel beam 1 for the cross beam. The diagonal material 12 is arranged in a letter C shape in front view, but is not limited to this and may have an inverted letter H shape. The upper and lower chord members 11a are respectively embedded in the cast-in-place upper floor slab 2 and the lower floor slab 3, and the left and right vertical members 11b are joined by a joining key or cast-in-place concrete on the end face of the precast truss panel 10 in the bridge axis direction. ing.

  FIG. 2 shows an example in which the main girder has a box girder structure (not limited to a one-chamber box girder but also includes two or more box girder), but a structure without a lower floor slab is also possible. FIG. 7 shows an example of a composite girder bridge having a plurality of girders, and a truss panel girder 1 is used for each girder.

In the case of the truss panel girder 1 configured as above,
(1) By making the precast truss panel 10 into a truss shape composed of the frame 11 and the diagonal member 12, it is possible to reduce the weight of the bridge girder web. Further, the truss members 11 and 12 are made of ultra high strength concrete. By using a pretension member, high shear resistance can be ensured, so that the web thickness can be reduced. As a result, the weight of the bridge superstructure can be greatly reduced, and the scale of not only the superstructure but also the substructure can be reduced. Various bridge construction methods have the following advantages and can be expected to reduce the cost of the entire bridge construction work.

-Overhang construction method: The construction length of one block can be lengthened and the number of overhang construction blocks can be reduced, so the construction period can be shortened.
Extrusion construction method: Construction equipment including the extrusion device can be made smaller.
・ Bulk construction method: Construction equipment such as girder construction equipment can be reduced.

  (2) By using the precast truss panel 10 made of concrete, compared with the composite structure of steel members such as corrugated steel plates, the costly manufacturing process of steel members is unnecessary, and rust prevention measures and their maintenance The cost can be saved and the complexity of on-site welding and the like is eliminated, so that the workability can be improved, the work period can be shortened, and the cost can be reduced.

  (3) By using the precast truss panel 10 composed of the frame 11 and the diagonal member 12, the web can greatly reduce the number of members constituting the truss as compared with the composite structure of the steel pipe truss. There is no need to reinforce the joints and the like, improving workability, shortening the construction period, and reducing costs.

  (4) By connecting the frame 11 and the precast truss panel 10 composed of the diagonal member 12 to form the truss panel web 1, the frame 11 continuously integrated in the bridge axis direction is continuously connected to the upper floor slab 2 and the lower floor slab 3 Can be joined together, local stress generated in the floor slab can be reduced, and the joint structure can be simplified.

  (5) If the mechanical shear key 14 is used for joining the panels 10, it is possible to rationalize and simplify the panel production and installation.

  (6) By precasting the truss panel web 1, the quality of the web can be improved, and the formwork and concrete placement work for web construction at the site can be omitted. Can be shortened and the cost can be reduced.

  (7) If the PC steel material 13 as the web shear reinforcement is a pre-tension method, a grout operation is not required as compared with the post-tension method, and labor saving and improvement in durability can be expected.

  In the above, the case where the present invention is applied to the bridge girder web and the cross girder of the bridge has been described. However, the present invention is not limited to this and can be applied to a pier, a footbridge, a slab, a deck structure, and the like. In the case of a slab or the like, precast truss panels are arranged vertically and horizontally on a plane and joined with a joining key, and a floor slab is provided thereon. Moreover, in the case of a bridge girder web, etc., the case where ultra high strength concrete was used was shown, but depending on the application, ordinary concrete may be used.

It is a side view which shows the basic structure of the bridge girder which used the truss panel girder of this invention for the web. It is the perspective view which made a part the cross section which shows an example of the prestressed concrete box girder bridge which used the truss panel girder of this invention for the web. It is a side view which shows the example of the truss format used by this invention, (a) is a Hau truss, (b) is a platform truss, (c) is a Warren truss. It is a vertical sectional view showing an example of a mechanical shear key of a joining key of a panel used in the present invention. It is the side view and front view which show the example of the concrete shear key of the panel used by this invention, (a) is a multistage shape, (b) is a waveform. It is a front view which shows the example which applied the truss panel girder of this invention to the horizontal girder of a bridge. It is a front view which shows the example of a bridge without a lower floor version.

Explanation of symbols

1 ... Truss panel web 2 ... Upper floor slab 3 ... Lower floor slab 4 ... Inner cable 5 ... Outer cable 6 ... Cross girder 10 ... Precast truss panel 11 ... Frame (outer frame)
11a ... truss upper and lower chord material 11b ... truss vertical member 12 ... diagonal member 13 ... truss member PC steel member 14 ... mechanical shear key 15 ... bridge shaft direction PC steel member 20 ... concrete shear key A ... ... Super high strength concrete

Claims (8)

  A truss panel girder used for a concrete structure girder, which is composed of an outer peripheral frame and diagonal members arranged in the outer peripheral frame, and these outer peripheral frame and diagonal members are made of concrete. Truss panel girder characterized by being constructed by joining a plurality of pieces.   The truss panel girder according to claim 1, wherein high-strength concrete is used for the concrete.   The truss panel girder according to claim 1 or 2, wherein prestress is introduced into a portion that receives tension.   The truss panel girder according to any one of claims 1 to 3, wherein the longitudinal members of the outer frame of the precast truss panel are joined together by a shear key means.   The truss panel girder according to any one of claims 1 to 4, wherein the upper chord member of the precast truss panel outer peripheral frame is integrated by a cast-in-place slab.   The truss panel girder according to any one of claims 1 to 5, wherein prestress in the longitudinal direction of the girder is introduced by a cable.   A precast panel used for a girder member of a concrete structure, which is composed of an outer peripheral frame and diagonal members arranged in the outer peripheral frame, and that the outer peripheral frame and the diagonal member are made of concrete. panel. A precast panel used for a girder member of a concrete structure, comprising an outer peripheral frame and diagonal members arranged in the outer peripheral frame, and the outer peripheral frame and diagonal members are formed of high-strength concrete, and the diagonal member Or precast truss panel that prestress is introduced to the outer frame by tension steel.

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