KR20160078150A

KR20160078150A - Segmental prestressed concrete girder and method for constructing same

Info

Publication number: KR20160078150A
Application number: KR1020140188973A
Authority: KR
Inventors: 김진국; 양준모; 성택룡
Original assignee: 주식회사 포스코
Priority date: 2014-12-24
Filing date: 2014-12-24
Publication date: 2016-07-04

Abstract

The present invention relates to a pneumatic tire comprising a pair of end blocks having a concrete member, an end duct penetrating the concrete member in the longitudinal direction, and a steel fiber mixed in the concrete member; A center block disposed between the pair of end blocks, the center block having a concrete member, a central duct penetrating the concrete member in the longitudinal direction, and a plurality of strands extending in the longitudinal direction embedded in the concrete member; And a tensioning device including a tension member passing through the end ducts and the central duct and a fixing member for fixing both ends of the tension member to the concrete member of the end block, The present invention provides a segmented prestressed concrete girder characterized by a square shape.

Description

TECHNICAL FIELD [0001] The present invention relates to a segmented prestressed concrete girder and a method of constructing the same.

The present invention relates to a segmented prestressed concrete girder as a whole and more particularly to a precast concrete block with high strength reinforced by a steel fiber on both ends where relatively large stress concentration occurs, The present invention relates to a segmented prestressed concrete girder and a method of constructing the same, which can eliminate the reinforcement by applying a pre-tension block using high-strength concrete together with a high strength strand.

It should be noted that the contents described in this section merely provide background information on the present invention and do not constitute the prior art.

The girder is installed on the upper part of the pier so that the bridge can secure the load-bearing capacity, and the concrete slab is placed on the bridge. Such a girder is a prestressed concrete girder manufactured by introducing a tension force to increase the load bearing capacity of a bridge or to resist deflection or crack generated by overload or use.

Prestressed concrete girder is a structure that can resist tensile force by introducing precompression force to concrete girder by using high strength steel wire to compensate characteristic of concrete which is vulnerable to tensile. In this case, as the length of the bridge increases, the height and width of the concrete section become larger in order to secure the rigidity and strength. In order to introduce the prestress into the enlarged section, tens of stranded wires should be installed.

Prestressed concrete and post tensioning methods are available for manufacturing prestressed concrete girders.

The pre-tension method is a method in which the steel wire is arranged in the longitudinal direction in advance, the concrete is laid after the tension is introduced, the concrete is hardened, and then the compressive stress is introduced into the concrete by releasing the tension force. In the post tension method, It is a method to introduce compressive stress to concrete by installing in advance, pouring concrete, hardening concrete, inserting steel wire and fixing tension on the end of concrete by introducing tension force.

The pretensioning method is advantageous in terms of quality and construction when it is manufactured and transported in a large quantity. However, since the steel wire must be strained in advance, it takes a lot of production equipment such as reaction force and long line bed, The post tension method is widely applied except that it can not be carried by a girder having a length of 15 m or more and is applied to a girder having a length less than that or applied to a girder manufactured in the field.

These prestressed concrete girders are composed of concrete, steel wire, and reinforcing steel. Here, reinforcing steel reinforces the bending strength and shear strength which are insufficient for concrete and stranded wire, and further reinforced to prevent non-structural cracking.

In particular, there is little bending around the fusing part, but a large amount of reinforcing bars must be laid to cope with the high shear stress of the fusible part together with the stress concentration occurring in the fixing process of the prestressing force. Also, since a plurality of fixing devices are pushed to the ends, complicated reinforcement can not be avoided, and the manufacturing cost of the reinforcement is increased.

On the other hand, the segmented prestressed concrete girders are manufactured by dividing one girder into a plurality of blocks and fabricating them in a factory or the like, and then connecting the blocks to each other in the field, installing tension members in the longitudinal direction, .

Since these blocks are manufactured in factories, the quality control is easy, and the manufacturing process except for the connection of beam and the introduction of tension is done at the factory, so the working air on the site can be drastically shortened. However, since there is a vague rejection and lack of reliability on joints of joints, there are not many applications.

Korean Patent Publication No. 10-2014-0121946 (published on October 17, 2014) Korean Patent Publication No. 10-2014-0121945 (published on October 17, 2014)

It is an object of the present invention to provide a segmented prestressed concrete girder having a precast block of high strength concrete applied to both ends thereof and a pretension block at the center thereof and a method of constructing the same. .

In order to achieve the above-mentioned object, the present invention provides a pneumatic tire comprising: a pair of end blocks including a concrete member, an end duct penetrating the concrete member in the longitudinal direction, and a steel fiber mixed in the concrete member; A center block disposed between the pair of end blocks, the center block having a concrete member, a central duct penetrating the concrete member in the longitudinal direction, and a plurality of strands extending in the longitudinal direction embedded in the concrete member; And a tensioning device including a tension member passing through the end ducts and the central duct and a fixing member for fixing both ends of the tension member to the concrete member of the end block, The present invention provides a segmented prestressed concrete girder characterized by a frame shape.

The present invention also provides a method of manufacturing a concrete block, comprising the steps of: preparing a pair of end blocks having end ducts penetrating a concrete member in a longitudinal direction by pre-casting using a mold; A step of preparing a center block having a rectangular cross section by releasing the tension of the strand after pouring and curing concrete with a plurality of strands preliminarily tensioned with the central duct; Inserting the end ducts arranged by arranging the center block between the end blocks and a tension member passing through the center duct; And applying a tension to the tension member and fixing both ends of the tension member to the concrete member of the end block through a fixing member, respectively. The present invention also provides a method of constructing a segmented prestressed concrete girder.

The segmented prestressed concrete girder according to the present invention is characterized in that a precast block of high strength concrete reinforced with steel fiber is applied to both ends and a pretilt block using high strength concrete is applied to the center portion along with a high strength strand, It is possible to reduce the material cost and human power consumption and improve the workability.

According to the present invention, reinforcement of steel fiber and high-strength stranded wire can be used to omit reinforcement and compensate for tensile stress of concrete. Thus, by eliminating the use of reinforcing bars, the shape of the end portion is made slimmer, The cross-sectional shape of the girder can be uniformly formed.

1 is a perspective view illustrating a segmented prestressed concrete girder according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view schematically showing the segmented prestressed concrete girder shown in FIG. 1; FIG.
3 is an enlarged cross-sectional view of a portion A in Fig.
4 is a sectional view taken along line BB of Fig.
5 is a perspective view showing the connection end of the block;

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a segmented prestressed concrete girder according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a segmented prestressed concrete girder according to an embodiment of the present invention, FIG. 2 is a sectional view schematically showing a segmented prestressed concrete girder shown in FIG. 1, and FIG. 3 is a cross- Fig. 4 is a sectional view taken along the line BB in Fig. 2, and Fig. 5 is a perspective view showing a connecting end portion of the block.

As shown in these drawings, the segmented prestressed concrete girder 100 is composed of a concrete member 11, an end duct 15 penetrating the concrete member 11 in the longitudinal direction, and a concrete member 11 A pair of end blocks 10 having steel fibers 13 incorporated therein; A concrete duct member 21 having a central duct 25 penetrating the concrete member 21 in the longitudinal direction and a plurality of stranded wires 22 extending in the longitudinal direction in the concrete member 21, A central block (20) disposed between the pair of end blocks (10); A tension member 31 passing through the end ducts 15 and the central duct 25 and a fixing member 31 for fixing both ends of the tension member 31 to the concrete member 11 of the end block 10 32). &Lt; / RTI >

The end block 10 is preferably manufactured in the factory by pre-casting using a mold so that it can be manufactured with high quality. However, it is not necessarily limited to this, but it may be produced on the spot. Each end block 10 is preferably made to have a length of 1/3 or less of the total length of the girder.

The concrete member 11 may be formed to extend along the longitudinal direction of the girder. The concrete member 11 is formed using high-strength concrete of about 70 to 100 MPa, and the steel fiber 13 can be incorporated to reinforce the concrete member 11. [

The steel fiber (13) can compensate the tensile strength, which is a disadvantage of concrete, and can control the occurrence of temperature cracks such as shrinkage and freezing and thawing, and improve the resistance performance against shear load, cyclic load and impact load. By reinforcing the steel fiber 13, it is possible to omit the reinforcing bars in the end block 10.

The end duct 15 is a member for receiving the tension member 31 which is used to connect the central block 20 and to introduce the post tension and is located so as to penetrate the concrete member 11 longitudinally, In the concrete member 11. The end duct 15 is made of a metal or the like, and at least one end duct 15 may be provided, and preferably two end ducts 15 may be provided. Thereby, at least one or two tension members 31 are also provided.

As described above, the end block 10 is made of high-strength concrete and steel fiber to improve the shear resistance, thereby eliminating the reinforcement of the reinforcing bars.

The center block 20 can be manufactured in a factory or on the site using a pretensioning method. Here, the both ends of the center block 20 are formed by using the mold from which the end block 10 was manufactured, so that the assembly at the site can be facilitated. The center block 20 is made to have a length of 1/3 or more of the total length of the girder.

The concrete member 21 may be formed to extend along the longitudinal direction of the girder. The concrete member 21 is slimly shaped by using a high-strength concrete of about 50 to 100 MPa. In addition, the steel fiber 23 may be mixed to reinforce the concrete member 21. [

As shown in FIG. 4, the concrete member 21 is cut by cutting the both ends of the strand 22 extending outward after concrete is poured and cured in a state in which a plurality of strands 22 equally arranged are tensed. .

The strand 22 plays the role of a reinforcing bar in the center block 20 and a prestressing function is introduced to maximize the bending performance of the girder.

As described above, when the end face of the concrete member 21 is slimmed, the space for arranging the strand 22 is insufficient. To compensate for this, a strand of high strength of about 2000 MPa or more is applied to the strand 22.

As shown in FIG. 2, the center block 20 may be formed by partially incorporating the steel fiber 23 or by using a high-strength concrete as shown in FIG. 2, Performance can be improved.

According to an embodiment of the present invention, the cross section of the central block 20 is preferably a rectangular shape. When the cross section of the center block 20 is formed in a rectangular shape, it is possible to resist the introduction of stress due to the uneven settlement when the block is placed in the field.

Also, it is possible to determine the number of strands to be installed in the central block after determining the introduction amount of the pre-tension in an extent that upward deflection does not occur due to the manufacture of the central block incorporating the prestressing function.

At this time, the tensile strength of the strand can be 2000 MPa or more, preferably 2160 MPa.

According to the present invention, the cross section of the center block 20 can be configured to have a hollow rectangular or square shape with a hollow portion 27 at the center. And a flange (F) formed of a concrete member (21) is provided outside the hollow portion (27).

At this time, the central duct 25 is preferably provided on the lower flange 24. At this time, a plurality of the central ducts 25 may be provided.

The plurality of central ducts 25 are preferably arranged symmetrically with respect to the center line of the cross section of the center block 20. [

According to one embodiment of the present invention, the central duct 25 is provided with two, spaced by a predetermined distance in a symmetrical manner with respect to the center line of the cross section.

The central duct 25 is a member for receiving the tension member 31 used to connect the end blocks 10 and to introduce the post tension and is positioned so as to penetrate the concrete member 21 longitudinally, (22) and embedded in the concrete member (21) at the time of molding. The central duct 25 is made of a metal or the like and may be provided in one or a pair.

As described above, the central block 20 is provided with the prestressed tension lines 22 uniformly arranged in the cross section, so that the reinforcement of the reinforcing bars can be omitted, and the bending performance of the girder can be ensured. In addition, a part of the steel fiber may be mixed in the concrete member 21 of the center block 20 or the concrete member 21 may be formed of high strength concrete, so that the adhesion performance in which the high strength strand is adhered to the concrete can be improved.

The tensioning device 30 includes a tension member 31 composed of a bundle of high strength steel wires and a fixing member 32 for fixing both ends of the tension member 31 so as to provide tension to the girder, And the central block 20 are connected to each other.

The tension members 31 are arranged such that when the central block 20 is disposed between the pair of end blocks 10 and when they are aligned in a linear manner they are inserted through the end duct 15 and the central duct 25, do. At least one tension member 31 is provided, and preferably it is provided as a pair.

The tension member 31 is then tensioned using a tensioning device (not shown) such as a hydraulic jack and both ends of the tension member 31 are fixed to one end of the end block 10 using the fixing member 32, respectively. A grouting (50) is applied to the inside of the duct (15, 25).

In the present invention, when the end blocks 10 and the center block 20 are coupled to each other, the post tension method is used to introduce the prestress into the girders.

Referring to FIG. 1, the central block 20 may include a plurality of central blocks 20a and 20b according to an exemplary embodiment of the present invention.

When a plurality of central blocks 20a and 20b to which a pretension method is applied are connected to each other or a central block 20a to which a pretension method is applied and an end block 10 to which a post tension method is applied are connected, The bending deformation of the central blocks 20a and 20b may be an impeding factor connecting the blocks.

Alternatively, when joining the end block 10 and the center block 20 using the post tension method, there is a fear that the introduction amount of the post tension is insufficient, causing a fray in the connection portion.

In the present invention, the coupling between the center blocks 20a and 20b or between the center block 20 and the end block 10 can be performed tightly, and even when the center blocks 20a and 20b are bent A structure for enabling smooth coupling is disclosed.

Hereinafter, it will be described in detail with reference to Fig. 1 and Fig.

The structure of the connection end described below is applicable to both the connection end 17 between the end block 10 and the center block 20 and the connection end 29 between the center blocks 20a and 20b.

In addition, when the first block and the second block described below are adjacent to each other and applied to the connecting end 29 between the central blocks 20a and 20b, the first block and the second block are all connected to the center block The first block is applied to the center block 20 and the end block 10 and the second block is applied to the other block. .

1, the cross-section of the center block 20 and the cross-section of the connecting end 17 of the end block 10 are shown in a rectangular shape. However, the entire longitudinal direction of the end block 10 may be formed in a rectangular shape Of course. In this case, the end block 10 may have a rectangular or square shape having a hollow portion like the central block 20 described above.

Referring to FIG. 5, according to an embodiment of the present invention, the connecting end of the first block that engages with the connecting end of the second block may have protrusions 291 and 292.

Hereinafter, the case where the first block and the second block are the center block 20 is explained, but when the first block is one of the center block and the end block and the second block is the remaining one block, Lt; / RTI > That is, the connection structure described below is equally applicable to the connecting end 29 between the center blocks and the connecting end 17 between the center block and the end block.

5 (a), the projection 291 is located at the center of the connecting end 29 of the first block 20. In addition, the projecting portion 291 of the first block 20 is inserted into the hollow portion of the second block.

This embodiment can be applied when the first block 20 and the second block are rectangular or square with the hollow portion 27 (see Fig. 4).

The projecting portion 291 provided at the connection end 29 of the first block 20 may correspond to the shape of the hollow portion of the second block.

According to the embodiment, there is an advantage that a separate recess is not formed in the second block.

Referring to FIG. 5B, a plurality of protrusions 292 may be provided. At this time, the plurality of protrusions 292 are provided at the connection end 29 of the first block 20.

The first block 20 may be disposed at a predetermined distance along the flange F around the hollow portion 27 when the first block 20 has a rectangular shape having the hollow portion 27. [

A concave portion (not shown) corresponding to the plurality of protrusions 292 and into which the protrusions 292 are inserted may be formed at the connection end of the second block adjacent to the first block 20.

As described above, when the protruding portions 291 and 292 are formed at the connection end portions of the blocks to couple the two blocks, there is an advantage that the coupling can be tightened despite the bending deformation occurring in the block.

5 (b) shows an embodiment in which a hollow portion is not formed in the connection end portion 29 of the block 20. In this case, it can be connected to the adjacent block by the tension member 31 passing through the central duct 25.

Hereinafter, a method of constructing a segmented prestressed concrete girder according to the present invention will be briefly described.

A method of constructing a segmented prestressed concrete girder (100) according to the present invention comprises the steps of: fabricating a pair of end blocks (10) having an end duct (15) penetrating a concrete member (11) in the longitudinal direction; Preparing a center block (20) having a rectangular cross section by releasing tension of the strand (22) after pouring concrete and placing a plurality of strands (22) preliminarily strained with the central duct (20); Placing a central block (20) between the end blocks (10) and inserting a tension member (31) through the aligned end ducts (15) and the central duct (20); Tensioning the tension member 31 and fixing both ends to the concrete member 11 of the end block 10 via the fixing member 32, respectively.

The end block 10 is manufactured in the factory by pre-casting using a mold. A steel fiber 13 for reinforcing the concrete member 11 is mixed at the time of molding.

The central block 20 is fabricated in a factory or on site using a pretension technique. Here, both ends of the center block 20 can be formed by using the mold from which the end block 10 was manufactured. A steel fiber 23 for reinforcing the concrete member 21 may be incorporated when the central block 20 is manufactured. The center block 20 may have a rectangular or square cross section, and a hollow portion 27 may be formed at the center.

On the other hand, a plurality of central blocks 20 may be manufactured.

At this time, one central block 20a of the central block 20 is provided with protrusions 291 and 292, and the other central block 20b is provided with a hollow portion 27 corresponding to the protrusions 291 and 292, (Not shown).

Next, when the blocks are completed, they are transported to the installation site of the girder. In the field, a plurality of central blocks 20a and 20b are arranged in a line. In addition, the center block 20 is positioned between the end blocks 10 in a line.

When the central blocks 20a and 20b are aligned in a line, the protruding portions 291 and 292 may be inserted into the hollow portion 27 or the concave portion so that the center blocks may be arranged and joined in a line.

Thereafter the tension member 31 is inserted through the ducts 15 and 25 of the aligned blocks 10 and 20 and the tension member 31 is tensioned using the tensioning device, So that both ends of the tension member 31 are fixed to one end of the end block 10, respectively.

Finally, a grouting 50 is applied to the inside of the ducts 15 and 25 to complete the segmented prestressed concrete girder 100 according to the present invention.

These girders are mounted on alternating and pierched bridges, and the bridges are constructed through bottom plate casting, curing, and paving work.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

100: Segmented prestressed concrete girder
10: end block 20: center block
30: tension device 50: grouting

Claims

A pair of end blocks including a concrete member, an end duct penetrating the concrete member in the longitudinal direction, and a steel fiber mixed in the concrete member;
A center block disposed between the pair of end blocks, the center block having a concrete member, a central duct penetrating the concrete member in the longitudinal direction, and a plurality of strands extending in the longitudinal direction embedded in the concrete member; And
And a tensioning device including a tension member passing through the end ducts and the central duct and a fixing member for fixing both ends of the tension member to the concrete member of the end block, Concrete girder.

The method according to claim 1,
Wherein the cross-section of the center block is a frame-like shape.

The method according to claim 1,
Wherein the central block has a hollow rectangular or square cross section and a hollow portion at the center thereof.

The method according to claim 1,
Wherein the at least two central ducts are provided symmetrically with respect to the center line of the cross section of the center block.

5. The method of claim 4,
Wherein the plurality of central ducts are provided in a lower flange located below the hollow portion.

6. The method according to any one of claims 1 to 5,
Wherein a plurality of the center blocks are provided, and in a first block and a second block neighboring the center block and the end block,
And the connecting end of the first block engaging with the connecting end of the second block has a protrusion.

The method according to claim 6,
Wherein the connection end of the second block has a hollow rectangular or square shape and a hollow portion at the center, and the protrusion of the first block is inserted into the hollow portion of the second block.

The method according to claim 6,
Wherein a plurality of protrusions are provided at a connection end of the first block and a concave portion corresponding to the protrusion is inserted into the connection end of the second block to receive the protrusion.

The method according to claim 1,
And the central block is mixed with a steel fiber to reinforce the concrete member.

The method according to claim 1,
A segmented prestressed concrete girder to which a strand of at least 2000 MPa is applied as the strand.

Forming a pair of end blocks with end ducts longitudinally penetrating the concrete member by pre-casting using a mold;
A step of preparing a center block having a square cross section by releasing the tension of the strand after pouring and curing concrete with a plurality of strands preliminarily tensioned with the central duct;
Inserting the end ducts arranged by arranging the center block between the end blocks and a tension member passing through the center duct; And
Applying a tension to the tension member and fixing both ends to a concrete member of the end block through a fixing member;
Wherein the method comprises the steps of:

12. The method of claim 11,
In the process of manufacturing the center block, a plurality of center blocks are manufactured, and protrusions provided in one of the neighboring center blocks are inserted into hollows or recesses provided in another neighboring central block, The method comprising the steps of:

12. The method of claim 11,
Wherein a steel fiber is mixed to reinforce the concrete member during a process of manufacturing the end block or a process of manufacturing the center block.

12. The method of claim 11,
Wherein the center block is manufactured by molding both ends of the center block by using a mold from which the end block is manufactured.