KR20050015572A - Prestressing apparatus and construction method for making into continuous prestressed concrete beam using thereof - Google Patents

Abstract

PURPOSE: A continuation method of a PSC beam using a temporary prestressing apparatus is provided to install and dismantle a prestressing apparatus simply and to improve the efficiency on prestressing by installing a prestressing apparatus on a beam temporarily, to reduce the waste of materials and the cost required by recycling a prestressing apparatus, to secure the stiffness and durability of a bridge by continuing completely by prestressing on a spot joint of a negative moment section and to prevent the damage of a concrete beam by prestressing temporarily using a prestressing apparatus. CONSTITUTION: The continuation method of a PSC beam using a temporary prestressing apparatus comprises the steps of: applying prestress temporarily by installing an external tendon(40) on a concrete beam(2) with a sheathe pipe(4); pulling up the prestressed concrete beams(2), then placing on a pier in order; completing a field joint(60) by connecting the pre-laid sheathe pipes(4) of adjacent concrete beams(2) mutually and placing concrete on a spot joint of the placed concrete beam(2); installing crossbeams(70) on the connected concrete beams(2); placing prestress all over the span by inserting continuous tendons(80) to the concrete beams(2) to be continuous on the whole span, then tensioning and anchoring; and removing prestress by an external tendon(40) by un-anchoring the external tendon(40) installed on the outside of each concrete beam(2) and removing a prestressing apparatus.

Description

Prestressing apparatus and construction method for making into continuous prestressed concrete beam using techniques

The present invention relates to a sequencing method of prestressed concrete beams (hereinafter referred to as "PS beams") using a hypothetical prestressing device and a prestressing device used therefor. By reinforcing by applying temporary prestress to each of the plurality of concrete beams manufactured in a short span, it is possible to prevent the damage caused by the weight of the concrete beams, and to mount the plurality of concrete beams in the piers and to apply the tension material over the entire span. The present invention relates to a method of completely sequencing the entire span by applying continuous prestressing and a new prestressing device having a new structure for easily and effectively introducing a temporary prestress into the concrete beam.

In general, a continuous PS beam beam bridge is constructed by mounting a PS beam made of a plurality of short spans on a bridge and connecting each PS beam. PS beams manufactured with short spans are either pre-stressed at the time of manufacture (pre-tension method) or pre-stressed individually for each span just before the beam is completed and placed on the piers (post-tension method). ).

In other words, in the case of continuous PS beam bridges, each pre-stressed beam has a structure in which concrete is simply poured in the continuous part in the state where prestress is individually introduced, and a tension member is formed as a whole of the superstructure of the bridge. Not connected to each other. Therefore, in the related art, in order to control the parent moment generated in the continuous portion of the beam, a method of separately installing a tension member only in the continuous portion was adopted.

However, even after the pre-stress is individually introduced to each of the short-diameter concrete beams, a separate tension member is installed in the continuous portion and additional prestress is introduced in the continuous portion. This incompleteness makes the continuum structurally fragile.

The present invention was developed to solve the above problems, and the ultimate object of the present invention is to continuously connect a plurality of short span PS beams, not merely to connect the concrete of the beam, but also to the tension material installed on the beam. By arranging the beams together, tension can be introduced for the entire span at the same time, resulting in more robust continuity of the beam.

In addition, the present invention can be easily and simply added to the pre-stress to temporarily remove the pre-stress in order to prevent the concrete beam is damaged by its own weight, etc. in the process of achieving the complete continuity of the beam, it can be easily removed later Another object is to provide a new structure of prestressing device.

In order to achieve the above object, in the present invention is a method of sequencing by arranging the PS beams produced in a short span in a multi-span and connected to each other, by installing an external tension material for the concrete beam pre-buried sheath tube Temporarily introducing prestress; Lifting the concrete beams into which the prestress is introduced and sequentially placing them on the piers; At the pointed joint of the mounted concrete beam, allowing the adjacent concrete beams to communicate with the pre-embedded sheath pipe and completing the site joint by pouring concrete to the pointed joint; Installing a cross beam on the connected large concrete beams; Introducing prestress over the entire span by inserting a continuous tension member into the concrete beams continuously over the entire span and then tensioning and fixing it; And removing the prestressing device by removing the prestressing device and removing the prestressing device installed on the outside of each concrete beam, thereby removing the prestress caused by the external tension material.

In the present invention, the pre-stressing device having a structure that can be easily installed and dismantled the external tension material to be effectively used in the above sequencing method, the end installation member temporarily installed without being permanently fixed on the upper surface of both ends of the concrete beam; Guide members protruding from both sides of the abdomen of the concrete beam below each of the end installation members to bend and guide the external tension member upward; A saddle member that is simply simply seated upward without being permanently fixed to the center lower surface of the concrete beam; And external tension members at both side portions of the concrete beam, the outer tension members being fixed to the end mounting members at both ends of the saddle member via the lower surface of the saddle member and the guide member. The prestressing device is characterized in that the prestress is introduced to the concrete beam by pressing the saddle member upward while being guided by the guide member.

In the prestressing device as described above, the guide member, including a roller rotatably installed on both sides of the abdomen of the concrete beam, may be configured to guide the tension or relaxation of the external tension member while the roller is rotated.

In addition, in the prestressing device as described above, the external tension member is preferably configured to be fixed to the end installation member by a fixing nut.

In addition, in the prestressing device as described above, the saddle member, the support plate seated on the lower surface of the concrete beam, and having a width corresponding to the width of the concrete beam is extended upward from both sides of the upper surface of the support plate to move in the width direction of the support plate And an upward extension portion formed with an opening groove for horizontal beam installation thereon, and a guide extending downward from both sides of the lower surface of the support plate to guide the external tension member and at the same time to prevent the release of the support plate. Both sides of the upward extension may be configured to be installed adjusting screws for adjusting the center of the saddle member.

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

Prior to explaining the construction method according to the present invention, the configuration of the prestressing device according to the present invention for temporarily applying prestress to the outside of the PS beam manufactured in a short span will be described.

1A and 1B illustrate a state in which a prestressing device according to a preferred embodiment of the present invention is installed in a concrete beam, a side view is shown in FIG. 1A, and a plan view is shown in FIG. 1B.

Figures 2a to 2c shows a preferred embodiment of the end mounting member 10 and the guide member 20 provided in the prestressing device of the present invention in detail, Figure 2a is a perspective view of the main portion, Figure 2b FIG. 2A is a view seen from the direction “A” of FIG. 2A, and FIG. 2C is a view seen from the direction “B” of FIG. 2A.

As shown in FIGS. 1A and 1B, the prestressing device of the present invention includes an end installation member 10, a guide member 20, and a saddle member 30.

The end installation member 10 is fixed to both ends of the concrete beam 2 between short diameters, specifically, is provided in the transverse direction on the upper surface of both ends of the concrete beam 2. End portions of the outer tension member 40 are respectively fixed to both sides of the end installation member 10.

This end installation member 10 is installed in the form of simply placed on the upper surface of the concrete beam (2), unlike the conventional tension fixing device that is permanently fixed to the concrete beam (2) by an anchor or the like. Therefore, no damage occurs to the concrete beam 2 even if the end installation member 10 is installed, and mounting and removal of the end installation member 10 are easy.

The guide member 20 is installed to protrude to both sides of the abdomen of the concrete beam (2) below the end installation member (10). The guide member 20 serves to guide the external tension member 40 to pass through the end installation member 10 and the saddle member 30. In particular, as will be described later, when the external tension member 40 is tensioned while the external tension member 40 is wound on the outside of the guide member 20, the tension force applied to the external tension member 40 is increased by the end installation member ( 10) acts as a force to move to a position perpendicular to the guide member 20. Thus, the end installation member 10 is automatically in a position perpendicular to the guide member 10.

In other words, the tension force by the external tension member 40 acts to maintain the state in which the end installation member 10 is located in a direction perpendicular to the guide member 20. Therefore, even if the end installation member 10 is not artificially fixed by mobilizing a separate means such as an anchor, the end installation member 10 will be stably fixed to the upper surface of the concrete beam 2.

Next, the saddle member 30 is provided in the transverse direction on the central lower surface of the concrete beam (2), the outer tension member 40 passes through both sides thereof. Since the saddle member 30 is not permanently fixed to the concrete beam 2 by an anchor or the like, it does not damage the concrete beam 2 and is easy to install and remove.

As described above, in the state in which the end installation member 10, the guide member 20 and the saddle member 30 is installed, the external tension member 40 is disposed on both sides of the concrete beam 2 and then the external tension member 40 is disposed. When the tension is settled in the end installation member 10, the outer tension member 40 is guided to bend by the guide member 20 while prestressing the saddle member 30 by pressing the saddle member 30 upward. Is introduced.

Looking at the configuration of an embodiment of the end installation member 10, the guide member 20 and the saddle member 30 described above with reference to Figures 2a to 2c, first, the end installation member 10 is a seating plate 11 and the downward extension 12 can be configured. The seating plate 11 is not separately fixed by an anchor or the like and is simply installed on an upper end surface of the concrete beam 2.

At both ends of the seating plate 11, end fixing holes 41 of the external tension member 40 are fixed. That is, the end fixing unit 41 of the outer tension member 40 is inserted into the through hole formed in the seating plate 11 and then fixed by the fixing nut 42.

As such, in the present invention, since the external tension member 40 has a structure in which the external tension member 40 is fixed and fixed by the fixing nut 42, the external tension member 40 can be easily further tensioned by adjusting the fixing nut 42 later. It is easy to fine-tune the tension.

On the other hand, the downward extension portion 12 extends from both sides of the lower surface of the seating plate 11, the width of both downward extension portion 12 has a width corresponding to the width of the concrete beam 2 concrete By being covered on both sides of the beam (2) to limit the movement of the seating plate 11, that is, the end installation member 10 in the width direction to be installed on the concrete beam (2) and prevent the separation. A reinforcing rib 13 may be further provided between the seating plate 11 and the downwardly extending portion 12.

Next, the guide member 20, as described above, guides the external tension member 40, in the embodiment shown in the figure, is rotatably installed on both sides of the abdomen of the concrete beam (2) It is comprised including the roller 21. The roller 21 is guided by bending the external tension member 40 while being rotated by tension or relaxation of the external tension member 40.

In the embodiment shown in the drawings, the roller 21 is used as the guide member 20, but the present invention is not limited to this, the outside of the installation of a simple form of steel rods that do not rotate in place of the roller 21 The tension member 40 may be simply guided.

In the embodiment shown in the figure, the roller 21 is rotatably installed on the support steel bar (22). The supporting steel bar 22 passes through the abdomen of the concrete beam 2 and provides the rollers 21 at both ends thereof.

For the installation of the support steel bar 22, the protective pipe 23 is embedded in the concrete beam (2) in advance before the concrete casting, the supporting steel bar 22 after passing through the protective pipe (23) It is fixed by the washer 24 and the steel rod support nut 25 on both sides.

The roller 21 is rotatably inserted into the support steel bar 22 outside the steel support nut 25. The stop nut 26 is fastened to the outside of the roller 21 to prevent the roller 21 from being separated.

3A to 3C show a preferred embodiment of the saddle member 30 in detail, a perspective view in FIG. 3A, a front view of FIG. 3A in FIG. 3B, and a right side view of FIG. 3A in FIG. 3C. Are respectively shown.

3A to 3C, the saddle member 30 used in the present invention includes a support plate 31 seated on the lower surface of the concrete beam 2, and the width of the concrete beam 2. An upward extension having an opening corresponding to the width direction of the support plate 31 is extended upward from both sides of the upper surface of the support plate 31 and the opening groove 32 for the horizontal beam installation on the top ( 33). In addition, the saddle member 30 includes a guide 34 extending downward from both sides of the lower surface of the support plate 31 to guide the external tension member 40 and at the same time to prevent its separation.

Both side upward extension portions 33 of the support plate 31 is provided with an adjustment screw 50 for adjusting the center of the saddle member 30, that is, the center. The adjusting screw 50 passes through the installation hole (33a) formed in the upward extension portion 33, the end thereof is in contact with the inclined surface (2a) of the concrete beam (2). A nut 51 is embedded in the installation hole 33a of the upwardly extending portion 33 to adjust the adjustment screw 50.

Therefore, after the saddle member 30 is installed, the widthwise eccentricity of the saddle member 30 with respect to the concrete beam 2 can be corrected by adjusting the adjusting screws 50 on both sides to have the same length.

In addition, the saddle member 30, as can be seen in Figures 3b and 3c, a curved surface 35 is formed at the lower end of the support plate 31 inside the guide 34 thereof. The curved surface 35 induces the external tension member 40 to be in uniform contact throughout the saddle member 30. In the absence of the curved surface 35, the external tension member 40 contacts only both ends of the saddle member 30 so that the stress is concentrated at the portion thereof. In the present invention, the curved surface 35 is provided. This can prevent this stress concentration phenomenon. On the other hand, a reinforcing rib 36 is padded between the support plate 31 and the upwardly extending portion 33.

In the prestressing device of the present invention made as described above, the external tension member 40 can be easily and easily installed on the concrete beam 2 without damaging the concrete beam 2, and can be easily removed after use.

As described above, the guide member 20 by the tension force of the external tension member 40 to automatically position the end installation member 10 in a position perpendicular to the guide member 20, the end installation member Even if (10) is not artificially fixed by mobilizing another means such as an anchor, the same effect can be obtained.

When the guide member 20 is removed, the stop nut 26, the roller 21, the steel rod support nut 25, and the washer 24 are sequentially separated from the supporting steel bar 22, and then the protective tube ( 23) to remove the supporting steel bar (22). After removing the support steel bar 22 may be filled by filling the concrete (or grouting material) inside the protective tube (23).

The guide member 20 can also be used for the purpose of re-tensioning by reconnecting the tension member in the future maintenance by leaving it as it is without removing even after the construction of the bridge is completed.

Next, with reference to the accompanying drawings Figure 4 will be described the process of sequencing the PS beam of two or more intervals (three intervals in the figure) by the method according to the present invention.

When manufacturing the concrete beam 2, the sheath tube 4 is buried in advance inside. As described above, the concrete beam 2 produced in the state in which the sheath tube 4 is pre-embedded is temporarily prestressed before being mounted on the site. To this end, as shown in the figure, the prestressing device described above is installed on the outside of both sides of the concrete beam (2). Specifically, after installing the end mounting member 10, the saddle member 30 and the guide member 20 on both the upper surface, the center lower surface and both sides of the abdomen of the concrete beam (2), and arranged the external tension member 40, Temporary prestress is introduced into the concrete beam 2 by tensioning and fixing the external tension member 40 (a). As described above, using the prestressing device according to the present invention, it is possible to easily prestress the concrete beam (2).

Before the concrete beam 2 is mounted on the pier 6, stress is generated in the concrete beam 2 due to its own weight, etc. In the present invention, the prestressing device is installed outside the concrete beam 2 as described above. By applying temporary prestress to (2), it is possible to prevent damage to the concrete beam 2 due to stress generated by self weight or the like.

As a next step, the concrete beams 2 to which the temporary prestress is introduced as above are lifted and mounted on the pier 6 sequentially (b).

Next, at the point joint of the concrete beam 2 mounted on the pier 6 as described above, the pre-embedded sheath tube 4 is connected, and the longitudinal direction of the concrete beam 2 is adjacent to the adjacent beam. Reinforcing bars are structurally connected using a reinforcing bar coupler, and after the connection, the concrete is placed and cured at the point joints to complete the site joint 60 (c).

In this process, since the end installation member 10 according to the present invention is installed on the upper surface of the concrete beam 2, it does not interfere at all in forming the field joint 60. Therefore, construction can be made quickly and easily.

Next, the horizontal beam 70 is installed on the concrete beams 2 connected as described above (d). Here, in installing the cross beam 70 at the center of the beam 2, the cross beam 70 is an opening groove 32 (see FIGS. 3A and 3C) formed in the upward extension part 33 of the saddle member 30. It is installed through.

Subsequently, the tension member 80, such as a continuous PC strand, is inserted from one side of the sheath tube 4 connected as described above so that the tension member 80 is continuously disposed over the entire span. The tension member 80 continuously disposed as described above is tensioned and fixed at one or both ends of the continuous beam (f).

Subsequently, the prestressing device, which is installed outside the concrete beam 2 and the prestressing device including the external tension member 40, is removed (g), and the slab 90 is installed on the upper portion of the concrete beam 2 ( h).

When the prestressing device is removed, as described above, the prestressing device is temporarily installed in a temporary state without being permanently fixed to the beam, so that the removal operation is easy and can be quickly removed in a short time.

According to the present invention, since the sheath pipe 4 is continuous as described above, the tension member is inserted to be continuous so that the tension is integrated, so that the continuous state of each span is very assured, thereby showing the overall good structural behavior of the bridge.

For example, when a load is applied to the center of the span, the parent moment that is to be bent upward occurs at the point joint (continuous part). Therefore, it is difficult to achieve a reliable continuity of the bridge without controlling the parental moments at these point joints.

In the present invention, since the tension member 80 is arranged continuously at the point joint portion, and the prestress is introduced between the foreground by the tension member 80, the prestress is beamed at the center of the span of the beam 2 which is the constant moment section. It is introduced at the lower part of the part, and the pre-stress is introduced at the upper part of the point joint part which is a parent section, and the continuous continuation is attained.

In addition, since the parent moment is generated at the joint at the point joint, the constant moment in the center of the span generated at the bridge of the same span length is shared at the joint at the point joint. By controlling the cement, it is possible to reduce the design section of the bridge since the effect of reducing the static moment occurring at the center of the ground can be obtained.

In addition, when the prestress is introduced to the point joint as described above, the phenomenon that the upper part of the joint is open is suppressed, thereby reducing the occurrence of cracks in the upper bottom plate and improving the durability of the bridge.

As described above, the present invention is temporarily installed in a simple manner without permanently fixed to the beam, the installation and disassembly of the prestressing device is easy, and the workability for prestressing is improved.

In addition, the removed prestressing device can be used again, thereby reducing waste of material and saving costs.

In addition, in the present invention, the prestressing device is introduced to the point joint portion of the parent section without interrupting the sequential construction of the bridge, so that more reliable continuity is possible and the rigidity and durability of the bridge can be sufficiently secured.

On the other hand, before the concrete beams are mounted on the piers, prestresses are temporarily introduced using a new prestressing device that is easy to assemble and dismantle, thus preventing damage to the concrete beams due to the weight of the beams. Will be.

Figure 1a is a side view as a whole showing a state in which the prestressing device is installed on a concrete beam according to a preferred embodiment of the present invention

FIG. 1B is a top view of FIG. 1A

Figure 2a is a perspective view of the main portion showing in detail the end mounting plate and the guide member according to a preferred embodiment of the present invention

FIG. 2B is a view from the direction “A” of FIG. 2A

FIG. 2C is seen from the direction “B” in FIG. 2A

Figure 3a is a perspective view showing in detail the birds in accordance with a preferred embodiment of the present invention

3B is a front view of FIG. 3A

3C is a right side view of FIG. 3A

4 is a view sequentially showing a PS C beam continuous construction process according to a preferred embodiment of the present invention

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

2: concrete beam 4: sheath tube

6: pier 10: end mounting member

11: seating plate 12: downward extension

13 reinforcement rib 20 guide member

21: roller 22: support steel bar

23: sheath 24: washer

25: steel bar support nut 26: stop nut

30: saddle member 31: support plate

32: opening groove 33: upward extension

34: guide 35: curved surface

36: reinforcing rib 40: external tension material

41: end fixing unit 42: fixing nut

50: adjusting screw 51: nut

60: field joint 70: cross beam

80: continuous tension material 90: slab

Claims (5)

Continuity is achieved by arranging the PS beams made in short spans by connecting them with multiple spans. Installing an external tension member 40 with respect to the concrete beam 2 in which the sheath pipe 4 is pre-embedded to temporarily introduce prestress; Lifting the concrete beams 2 into which the prestress is introduced and sequentially placing them on the piers; At the pointed joint of the mounted concrete beam 2, adjacent concrete beams 2 communicate with the pre-embedded sheath pipe 4 and cast concrete at the pointed joint to connect the site joint 60 to the site joint 60. Completing; Installing a cross beam (70) on the connected large concrete beams (2); Introducing prestress over the entire span by inserting a continuous tension member (80) into the concrete beams (2) so as to be continuous over the entire span, and then tensioning and fixing them; And The PS beam comprising the steps of releasing the fixing of the external tension member 40 installed on the outside of each concrete beam (2) and removing the prestressing device to remove the prestress caused by the external tension member (40). Serialization method. An end installation member 10 temporarily installed on the upper surface of both ends of the concrete beam 2 without being permanently fixed; Guide members 20 protruding from both sides of the abdomen of the concrete beam 2 below the end installation members 10 to bend and guide the external tension member 40 upward; Saddle member 30 that is simply simply seated upwardly without being permanently fixed to the central lower surface of the concrete beam (2); And In both side portions of the concrete beam (2), via the lower surface of the saddle member 30 and the guide member 20, both ends of the external tension member 40 is fixed to the end installation member 10 including , When the external tension member 40 is tensioned and fixed, the external tension member 40 is bent and guided by the guide member 20, thereby prestressing the concrete beam 2 by pressing the saddle member 30 upward. A prestressing device, characterized in that it is introduced. The method of claim 2, The guide member 20 includes a roller 21 rotatably installed on both sides of the abdomen of the concrete beam 2, the roller 21 rotates the tension or relaxation of the external tension member 40. Prestressing device, characterized in that while guiding. The method according to claim 2 or 3, The external tension member 40 is prestressing device, characterized in that the fixing nut 42 is fixed to the end installation member (10). The method according to claim 2 or 3, The saddle member 30 is upwardly supported from both sides of the upper surface of the support plate 31 while having a width corresponding to the width of the support plate 31 seated on the lower surface of the concrete beam 2. Extends to restrict the movement of the support plate 31 in the width direction and extends downwardly from both sides of the lower surface of the support plate 31 and an upwardly extending portion 33 having an opening groove 32 for horizontal beam installation thereon; And guide the external tension member 40 and at the same time includes a guide (34) to prevent separation, the upper side extending portion 33 of the support plate 31 is adjusted for adjusting the center of the saddle member (30) Prestressing device, characterized in that the screw 50 is installed.