KR100541609B1 - Structure for debonding of prestressed concrete beam member with prestressing tendon and manufacturing method of prestressed concrete beam member thereby - Google Patents

Abstract

The present invention relates to a debonding structure of a prestressed concrete beam member having a tension member embedded therein, and a method of manufacturing the prestressed concrete beam member using the structure. Of prestressed concrete beam members (A) A multi-layered twisted wire (1a) which is a tension member formed by twisting a plurality of steel wires (1aa) while imparting tensile force to the main body (1) while being embedded in a predetermined portion of the lower end of the main body (1) in the longitudinal direction;

For debonding, the ends of both sides are tied so that the predetermined portions of both sides of the multi-layered stranded wire 1a buried in the tension state are covered, respectively, so that the multilayered stranded wire 1a is not attached to the concrete 3aa of the main body 1. It consists of the cover 1b.

In the present invention, since the debonding covers 1b are covered at both ends of the multilayered stranded wire 1a, which are respectively embedded in predetermined portions of the lower ends of the prestressed concrete beam members A, both ends of the prestressed concrete beam members A are provided. Unnecessary tensile force is not generated, and the cross-section of the prestressed concrete beam member (A) is reduced compared to the case of non-bonding structure, and the buried number of the upper tensile reinforcing bar can be cut in half, which is very simple at low cost. There is an effect that can be easily installed.

Prestressed concrete beam member, cover for debonding, inflection point, multi-layered strand, long line bed

Description

STRUCTURE FOR DEBONDING OF PRESTRESSED CONCRETE BEAM MEMBER WITH PRESTRESSING TENDON AND MANUFACTURING METHOD OF PRESTRESSED CONCRETE BEAM MEMBER THEREBY}

1 is a front view showing the inflection relationship of the beam member according to the load of the conventional PC beam member;

Figure 2 is a schematic front view of a state in which a steel wire which is a tension material bent from the upper side of both sides of the formwork for producing a prestressed concrete beam member by a conventional pretension method to the lower middle portion is arranged;

3A is a schematic front view of a state in which concrete is poured in a state in which a plurality of formwork is arranged in series on a tension table and a prestress is disposed at the same time by a conventional pretension method;

3B is a schematic enlarged longitudinal sectional view of portion C of FIG. 3A;

4 is a cross-sectional view taken along the line B-B in a state shown to the buried rebar in Figure 3b schematically shown,

5 is a perspective view of a prestressed concrete beam member embedded with a tension member of the present invention,

6 is a cross-sectional view taken along the line A-A of FIG.

7 is a perspective view of a cut type overlapping cover which is a cover for debonding of the present invention;

8 is a perspective view of a state where a cut type overlapping cover is applied to both ends of a multi-layered strand of the present invention;

9a to 9e is a schematic manufacturing process diagram showing a schematic process until the completion of the production of the prestressed concrete beam member using the debonding structure of the present invention,

10 is a perspective view of a non-cutting circular cover which is a debonding cover used in a prestressed concrete beam member as another embodiment of the debonding cover of the present invention;

FIG. 11 is a perspective view of the non-cut circular cover of FIG. 10 covered with both ends of the multilayer strand; FIG.

12a to 12d is a schematic manufacturing process diagram showing a schematic process until the completion of the prestressed concrete beam member using the debonding structure formed using the non-cutting circular cover of FIG.

FIG. 13 is an enlarged vertical cross-sectional view of part C of FIG. 12D.

<Description of the symbols for the main parts of the drawings>

 1: Body 1a: Multi-layered stranded wire

1b: Cover for debonding 2: Inflection point

 3: long line bed A, B: prestressed concrete beam member

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to prestressed concrete beam members incorporating tension members, and in particular, prestressed concrete beams having a cover for de-bonding a predetermined portion of both ends of a prestressing tendon. The present invention relates to a debonding structure of a prestressed concrete beam member having a tension member configured to prevent unnecessary tension from occurring at an upper end of both ends of the member, and a method of manufacturing the prestressed concrete beam member using the structure.

In general, buildings or bridges are manufactured in factories, and are constructed using reinforced PC beam members. At this time, the PC beam members become long spans, and a prestress line having a tension material as a tension material is embedded in the PC beam members. You will use rest concrete beam members.

The prestressed concrete beam member embeds a tension member in the formwork of the reinforced concrete beam and installs both ends of the tension member to protrude to the outside of the beam member, and then fixes it on a movable end fixing unit (detension jack) on one side. The prestressing chuck was placed on the other side to tension the strand.

After curing the concrete, the detent jack is relaxed and the strand wire is cut and a reverse camber is placed in the beam member to increase the protection against deflection and cracking of the member.

By using the prestressed concrete beam member, the structure of the high-load long span is easy, the design of a larger space is possible, and the structure with few cracks is obtained, and the structure with high durability can be constructed.

As shown in FIG. 2, the pistrest concrete beam member having a tension member embedded therein is an ideal prestress reinforcement method by arranging a twisted steel strand that is a tension member at a center lower portion and an upper portion of both ends thereof, as shown in FIG. 2. The same reinforcement method has a problem that can not produce a plurality of prestressed concrete beam members at the same time because it requires the additional measures to dedicate and raise the strand (1a) inside the concrete to reduce the workability.

To solve this problem, as shown in FIGS. 3A to 4, the long-line method, which is a method of manufacturing a plurality of prestressed concrete beam members by one prestressing, is used for the prestressed concrete beam members. There was a problem of embedding the reinforcing bar (1c) to control the tensile force on the upper side of the inside, and the cost increase because the cross section of the beam member must be increased as unnecessary tensile force occurs at both sides of the prestressed concrete beam member Of course, there was a problem that the construction is not easy.

The present invention has been made in order to solve the problems of the conventional prestressed concrete beam member, the object of the present invention is to prevent unnecessary tension from occurring at both ends of the prestressed concrete beam member, The present invention provides a debonding structure of a prestressed concrete beam member in which a tension member is not required to increase a cross section, and a method of manufacturing the prestressed concrete beam member using the structure.

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention will be described in detail.

(The same reference numerals as those used in the conventional drawings will be used for the drawings of the present invention which are the same as the conventional drawings.)

The debonding structure of the prestressed concrete beam member incorporating the tension member of the present invention is a predetermined portion inside the lower end of the rectangular parallelepiped main body 1 of the prestressed concrete beam member A, as shown in Figs. A multi-stranded strand (1a), which is a tension member formed by twisting a plurality of steel wires (1aa) while imparting tensile force to the main body (1) while being embedded in a tension state in a longitudinal direction;

The debonding where the ends of both sides are tied so as not to attach the multi-layered strands 1a to the concrete 3aa of the main body 1 while covering the predetermined portions on both sides of the multi-layered strand 1a embedded in the tension state. It is comprised by the cover 1b.

The debonding cover 1b of the present invention has a shape in which one side of the hollow cylinder cylindrical body is cut in the longitudinal direction, and a cut cover that overlaps both ends formed by cutting the one side {1bb (hereinafter, referred to as a cut overlap cover). Alternatively, as another embodiment, the non-cut circular cover 1ba of a hollow cylinder shape of which one side is not cut.

The cut overlapping cover 1bb is cut directly at predetermined portions on both sides, which are corresponding portions of the multi-layered strand 1a, which are buried in a tensioned state in the respective unit forms 3a, as shown in FIGS. 9A to 9E. Opening and pushing the cut part in the longitudinal direction of the type overlapping cover 1bb, the both sides of the multi-layered strand 1a are easily inserted into the cut type overlapping cover 1bb, and the cut type overlapping cover 1bb Both ends of the cut portion are overlapped and rolled up by a predetermined width to form an overlapped portion 1bb ', and the ends of the two sides are tied together so that the cut type overlap cover 1bb adheres to the multilayer strand 1a. Since the cutting type overlapping cover 1bb is covered, the concrete 3aa is formed so as not to penetrate and attach to the multilayer strand 1a.

The non-cut circular cover 1ba is inserted while pushing inward from each end of both sides of the multilayer strand 1a so that the multilayer strand 1a is smoothly inserted into the non-cut circular cover 1ba. In the state in which the predetermined portions on both sides of the multilayer strand 1a in the unit formwork 3a are respectively inserted in the hollow part, both ends of the non-cut circular cover 1ba are tied together and the multilayer strand 1a Since the non-cut circular cover 1ba is in close contact with the c), the concrete 3aa is constructed such that the portion where the non-cut circular cover 1ba is covered cannot penetrate and attach to the multilayer strand 1a.

The cutting type overlapping cover 1bb and the non-cutting circular cover 1ba are both sides of the main body 1 from a point at which the normal reinforcing bar becomes the same as the position of both side inflection points 2 of the PC beam member 5 which is reinforced. Covered to the outer end of the, the length of the portion where the non-cutting circular cover 1ba and the cut-type overlapping cover 1bb are covered on both sides of the multilayer strand 1a are respectively the total length of the multilayer strand 1a. The length corresponds to about 1/4 of the length of.

The material of the cutting type overlapping cover 1bb and the non-cutting circular cover 1ba, which is the debonding cover 1b, is preferably made of vinyl, but also prevents the concrete 3aa from penetrating and attaching to the multilayer strand 1a. It may be a cover body made of a material that can be used.

As the tension member, a prestressing strand is generally used as a high tensile strength steel.

In prestressed concrete, the initial prestress decreases over time due to the relaxation of the PS steel, the drying shrinkage of the concrete, and the creep.

As such, the effective prestress must remain after the initial prestress decreases, and the prestressed concrete steels must be tensioned with high tensile stress. Therefore, high-strength steel is required in prestressed concrete, and high-strength steel must be used for prestressed concrete to be tensioned so that a considerable amount of prestressing force remains after being destroyed by dry shrinkage and creep of concrete.

Next, a method of manufacturing the prestressed concrete beam member using the debonding structure of the prestressed concrete beam member in which the tension member of the present invention is embedded is as follows.

9a to 9e, the step of installing a plurality of unit formwork 3a at regular intervals in the prepared long line bed (3);

Installing both upper and lower reinforcing bars (1c) and stirrup bars (6) in each unit formwork (3a);

Installing the plurality of multi-layered strands (1a) through the inner lower ends of the respective unit forms (3a) at predetermined intervals, respectively;

Fixing one side of each of the plurality of multi-layered strands (1a) to a prestressing chuck (3b) respectively provided at one side of the long line bed (3);

Connecting the other side of the multilayer strand wire 1a connected to one side prestressing chuck 3b of the long line bed 3 to the movable end fixing unit 3c, and then tensioning the multilayer strand wire with the calculated tension force. Wow;

Placing a cut-over overlap cover (1bb), which is a debonding cover (1b), on a predetermined portion on both sides of the inner multi-layered strand (1a) of each unit formwork (3a);

Bundling both ends of the cut-type overlap cover (1bb) with a wire after completing the installation of the cut-type overlap cover (1bb);

Placing concrete 3aa in each unit formwork 3a;

Chopping the poured concrete 3aa;

Curing the compacted concrete 3aa;

A relaxation step of releasing the tension of the tensioned multi-layered strand (1a);

Cutting the multilayer strands (1a) for each unit formwork (3a);

After cutting the multi-layered strand 1a, each multi-layered strand that is fixed by cutting the overlapping cover 1bb on both sides of the lower end in the prestressed concrete beam member A by the step of demolding the unit formwork 3a. Production of the prestressed concrete beam member A in the state in which 1a is embedded at a predetermined interval is completed.

The debonding cover 1b is a case of using the cut type overlapping cover 1bb. The debonding cover 1b is formed by passing the multilayer strands 1a through the unit dies 3a, respectively, and then tensioning the multilayer strands 1a. Thereafter, the cut portions of the cut overlapping cover 1bb are placed on predetermined portions on both sides of the tensioned multilayer strand wire 1a in each unit die 3a, and the cut portions are opened, and then pushed to open the multilayer strand wire 1a. ) Is inserted into the hollow portion of the cutaway overlapping cover 1bb, and the multilayer strand wire 1a is inserted into the cutaway overlapping cover 1bb and the cut both sides of the cutaway overlapping cover 1bb naturally come into contact with each other. The overlapping portion 1bb 'is formed by overlapping each other while rubbing (FIGS. 9D, 9E, and 8), and by tying both ends of each cut type overlap cover 1bb with wires, the cut type overlap cover 1bb is formed. In the area covered with) concrete cannot penetrate At the site is no concrete is not attached to the multi-layered strand (1a).

Both sides of the multi-layered strand 1a are inserted into the hollow portion of the cut-away overlapping cover 1bb, and then both cut portions of the cut-away overlapping cover 1bb overlap and overlap each other to overlap the overlapping portion 1bb '. The reason why is formed is due to its elasticity due to the characteristics of the vinyl material and cylindrical structure of the cut-over overlap cover (1bb).

Compared to the conventional prestressed concrete beam member (A) having four tensile reinforcing bars 10, two reinforcing bars 1c and a plurality of stirrup reinforcing bars 6 on both sides of the lower part at regular intervals in the upper part of the present invention. Since the prestressed concrete beam member A is embedded with two tensile reinforcing bars 1c only on both sides of the upper part (the number of lower reinforcing bars 1c and the number of stirrup reinforcement 6 are the conventional prestressed concrete beam members ( The same as the number of A)) Since the buried number of the upper tensile reinforcing bar (1c) is reduced to about 1/2 than the conventional one, the cost is reduced.

Next, a method of manufacturing the prestressed concrete beam member in the case of using the non-cutting circular cover 1ba which is another embodiment of the present invention will be described.

12A to 12D, first inserting the multilayer strand 1a into hollow portions of the required number of non-cut circular covers 1ba, which are debonding covers 1b cut to a predetermined length; ;

Installing a plurality of unit formwork 3a at regular intervals in the prepared longline bed 3;

Installing reinforcing bars (1c) and stirrup reinforcing bars (6) on both sides of the upper and lower parts in each unit formwork (3a);

Installing a plurality of multi-stranded strands (1a) into which the non-cut circular covers (1ba) are pre-fitted at inner lower ends of the unit dies (3a) at predetermined intervals, respectively;

Fixing one side of each of the plurality of multi-layered strands (1a) to prestressing chucks (3b) respectively provided at one side of the longline bed (3);

After connecting the other side of the multi-layer stranded wire (1a) connected to one side prestressing chuck (3b) of the long line bed (3a) to the movable end fixing unit (3c) which is a tension jack, the multi-layered stranded wire with the calculated tension Tensioning;

Realigning the non-cutting type circular cover (1ba) so as to come to the part of the multi-layered twisted line (1a) at both inner ends of each unit formwork (3a) to complete the installation of the non-cutting type circular cover (1ba);

Bundling ends of both sides of the non-cutting circular cover 1ba, which is the debonding cover 1b, with wires after completing the installation of the non-cutting circular cover 1ba;

Placing concrete 3aa in each unit formwork 3a;

Chopping the poured concrete 3aa;

Curing the compacted concrete 3aa;

A relaxation step of releasing tension of the tensioned multilayer strand 1a;

Cutting the multilayer strand (1a) for each unit formwork (3a);

After cutting the multi-layered strand 1a, each multi-layered strand in which non-cut circular covers 1ba are fixed to both sides of the lower ends in the prestressed concrete beam member A by the step of demolding the unit formwork 3a. Production of the prestressed concrete beam member A in the state where 1a is embedded at predetermined intervals is completed.

In the portion where the non-cutting circular cover 1ba is covered, the non-cutting circular cover 1ba is formed by tying the characteristics of the non-cutting circular cover 1ba and the ends of both sides of the non-cutting circular cover 1ba, respectively, with a wire. Since concrete cannot penetrate at the site marked 1ba, the concrete is not attached to the multilayer stranded wire 1a at this site.

The cut overlapping cover 1bb of the debonding cover 1b of the present invention is the cutaway overlapping cover 1bb in advance on the multilayer strand 1a as shown in FIGS. 12A to 12D, which is another embodiment of the present invention. ) May be used.

The non-cut circular cover 1ba is formed at each end of the non-cut circular cover 1ba so that the multilayer stranded wire 1a is inserted into the hollow portion of each non-cut circular cover 1ba. After inserting into the hollow portion, while pushing the non-cutting circular cover 1ba, the multi-layered strand 1a may be inserted into the hollow portion of each non-cutting circular cover 1ba.

The unit formwork (3a) is installed on the inner bottom surface of the long line bed (3) is coupled to each other by only fastening bolts of each side portion of the four parts and the upper side is open.

The multilayer stranded wire 1a is installed by passing through holes formed in both sides of each unit formwork 3a, and one end of the multilayered stranded wire 1a is formed on one side prestressing post of the long line bed 3 to the prestressing chuck. The other end of the multi-layered stranded wire 1a is fixed to the movable end fixing unit 3c provided to be movable by the jack 3d provided on the other side of the long line bed 3 so as to be movable. By pulling the multi-layer stranded wire (1a) by the tension).

The length of the part where the cut overlapping cover 1bb and the non-cut round cover 1ba are covered on both sides of the multi-layered strand is respectively from one inflection point to one end of the beam member as shown in FIG. 1 or the other inflection point of the beam member. Is the same length as the distance from the other end to the other end (the distances from the two inflection points to the outer ends are equal to each other), and are each about one quarter of the total length of the multilayer strand 1a. . The outer end of the debonding cover 1b on one side and the outer end of the debonding cover 1b on the other side are configured to be seen from the outside.

The debonding structure of the prestressed concrete beam member in which the tension member of the present invention configured as described above is incorporated, and an operation related to a method of manufacturing the prestressed concrete beam member using the structure will be described.

Cut-over overlapping cover 1ba or non-cutting circular cover, which is the debonding cover 1b, at both ends of each of the plurality of multi-layered strands 1a, which are buried under tension in the lower end of the prestressed concrete beam member A. Since 1 bb is covered and fixed to each other, the tensile force at the upper end of the prestressed concrete beam member A generated by the multilayer strand 1a is attenuated, but the debonding cover 1b is not formed. Tensile force acts only on the part of the multi-layered strand 1a of the middle portion, which is not a portion, and the tensile stress occurring in the prestressed concrete beam member A is smoothly canceled, thereby prestressing concrete by the action of the multi-layered strand 1a, the tension member. Tensile stress does not occur at both ends of the beam member A, thereby controlling the unnecessary force of the fleece concrete beam member.

The reason why the tensile force is controlled and attenuated at the portion covered with both sides of the debonding cover 1b of the multilayer strand 1a is that the concrete 3aa and the multilayer strand 1a are depressed by the debonding cover 1b. This is because the bonding cover 1b is in a state where the bonding cover 1b is not attached to each other at the portion covered by the multilayer strand wire 1a.

That is, because the tensile force may be generated by the tension of the multi-layer strand (1a) in the tension state only in the portion where the multi-layer strand (1a) and concrete (3aa) is attached to each other.

When the non-cutting circular covers 1ba, which are other embodiments in which one side of the debonding cover 1b is not cut in the longitudinal direction, are fitted to the multilayer strand 1a, they must be inserted from the end of the multilayer strand 1a. Therefore, the cut overlapping cover 1bb, which can be inserted directly at a predetermined portion of the multi-layered twisted line 1a, is easier to insert and insert the multi-layered twisted line 1a than the non-cut round cover 1ba. It can be made easily.

As described above, in the present invention, since the debonding cover 1b is covered at both ends of the multilayer strand 1a embedded at a predetermined position of the lower end of the prestressed concrete beam member A, the prestressed concrete beam member ( Unnecessary tensile force is not generated on both ends of A) (i.e., the concrete 3aa and the multi-layered strand 1a of the intermediate portion, which are not both ends of the multilayer strand 1a covered with the debonding cover 1b). ) The tensile force acts only on the part where) is attached, which smoothly cancels the tensile force occurring in the prestressed concrete beam member (A), thereby increasing the protection against deflection and cracking of the member. Need not be increased (25-30% reduction in cross section of prestressed concrete beam members compared to non-bonding structures) Using only cut-over type overlap cover (1ba) or non-cut round cover (1bb) for debonding, the number of buried reinforcing bars (1c) on the upper part of the prestressed concrete beam member (A) is reduced by about 1/2 compared to the conventional one. Since it can be done, it is very simple and easy to install at low cost.

Claims (9)

A multi-layered strand wire which is a tension member formed by twisting a plurality of steel wires to impart a tensile force to the main body while being buried in a longitudinal state in a predetermined portion of the lower end of the main body of the prestressed concrete beam member; Debonding of a prestressed concrete beam member with a tension material, characterized in that it is composed of a debonding cover each of which is covered so that the multilayer stranded wire is not attached to the concrete at predetermined positions on both sides of the multilayer stranded wire embedded in the tension state. rescue. According to claim 1, The debonding cover is a state in which one side is cut in the longitudinal direction, the multi-layer strand is rolled so that the two sides formed by the cut so that the multilayer strand is not attached to the concrete close to each other by a predetermined width The debonding structure of the prestressed concrete beam member with a tension member, characterized in that the overlapping overlapping portion is formed is a cut-over type overlap cover is tightly bonded to the multi-layered strand by the end portions of both sides are tied. According to claim 1, wherein the debonding cover is a non-cut circular cover of a hollow cylindrical cylindrical shape that is in close contact with the multi-layer strand is tied to the ends of both sides so that the multi-layer strand is not attached to the concrete, the presisting tension material is built-in Debonding structure of the rest concrete beam member. The debonding structure of a prestressed concrete beam member with a tension member according to any one of claims 1 to 3, wherein the debonding cover is made of vinyl material. Installing a plurality of unit formwork at regular intervals in the prepared longline bed; Installing reinforcing bars and stirrup reinforcing bars on both sides of the upper and lower parts in each unit formwork; Installing a plurality of multi-layered strands through inner spaces of the unit dies at predetermined intervals, respectively; Fixing one side of each of the plurality of multilayer strands to a prestressing chuck respectively installed at one side of the longline bed; Connecting the other side of the multilayer strand wire connected to one prestressing chuck of the long line bed to the movable end fixing unit and tensioning the multilayer strand wire with the calculated tension force; Installing cut-over overlapping covers on predetermined portions of both sides of the inner multi-layered strand of each unit formwork; Bundling both ends of the cut-type overlapping cover with a wire after completing the cut-type overlapping cover installation work; Placing concrete in each unit formwork; Chopping the poured concrete; Curing the compacted concrete; A relaxation step of releasing the tension of the tensioned multilayer strand; Cutting the multi-layered stranded wire for each unit formwork; A method of manufacturing prestressed concrete beam members using a debonding structure, characterized in that the prestressed concrete beam member is produced by the step of demolding the unit formwork after the multilayer strand is cut. 6. The debonding structure according to claim 5, wherein the cut-out overlapping cover has an overlapping portion in which one side portion is cut in the longitudinal direction, and the cut portions overlapping each other by a predetermined width are formed. Method of manufacturing prestressed concrete beam members using The method of manufacturing a prestressed concrete beam member using a debonding structure according to claim 5 or 6, wherein the cut type overlapping cover is made of a vinyl material. Inserting the multi-layered strand into the hollows of the required number of non-cut circular covers which are debonding covers cut to a predetermined length; Installing a plurality of unit formwork at regular intervals in the prepared longline bed; Installing reinforcing bars and stirrup reinforcing bars on both sides of the upper and lower parts in each unit formwork; Installing a plurality of multi-stranded strands in which the non-cut circular covers are pre-inserted at inner lower ends of the unit dies at predetermined intervals, respectively; Fixing one side of each of the plurality of multilayer strands to prestressing chucks respectively installed on one side of the longline bed; Connecting the other side of the multilayer strand wire connected to one prestressing chuck of the long line bed to the movable end fixing unit, which is a tension jack, and tensioning the multilayer strand wire with the calculated tension force; Realigning the non-cutting circular cover so as to come to the part of the multi-layered strand in the inner side of each unit formwork to complete the non-cutting circular cover installation work; After completing the non-cutting circular cover installation work, tying the ends of both sides of the non-cutting circular cover with wires, respectively; Placing concrete in each unit formwork; Chopping the poured concrete; Curing the compacted concrete; A relaxation step of releasing tension of the tensioned multilayer strand; Cutting the multi-layered strands into respective unit dies; After the multilayer strand is cut, the prestressed concrete beam member using a de-bonding structure characterized in that the prestressed concrete beam member is produced by demolding the unit formwork. The method of manufacturing a prestressed concrete beam member using a debonding structure according to claim 8, wherein the non-cut circular cover is made of a vinyl material.

Images