KR20040054639A - External Prestressing Method of PS Concrete Composite Girder Bridge by Anchoring and Holding Tendon on Precast Cross-Beam - Google Patents

Abstract

PURPOSE: An external prestressing method of a PS concrete composite girder by a tendon anchored/supported to a prefabricated beam is provided to apply external tensile force without the control of traffic volume or the removal of a board, to compensate or reinforce tensile force, to have a wide working space and to prevent the damage of a girder. CONSTITUTION: The external prestressing method of a PS concrete composite girder bridge by a tendon anchored and supported to a prefabricated cross beam comprises the steps of anchoring/supporting an anchorage(10) and a holding anchorage(14) buried in a cross beam while fixing to a joint reinforcing steel box of a prefabricated cross beam, fixing an anchorage(10) of an external tendon(20) to a joint steel box(14) of a support cross beam(11), and fixing a supporter(14) to a joint steel box(16) of a beam(15) or a joint steel box of an inner support cross beam to change the direction of the external tendon(20). The tensile force applied on a cross beam by the external tendon(20) is transferred to a PS concrete girder or a composite girder by perpendicular frictional connection of the cross beam-girder joint reinforcing steel boxes(16) of a prefabricated intermediate cross beam(15) and an inner support cross beam by end bearing pressure on an anchoring end.

Description

External Prestressing Method of PS Concrete Composite Girder Bridge by Anchoring and Holding Tendon on Precast Cross-Beam}

The demand for an external prestressing method is rapidly increasing as a result of the improvement of rust prevention technology for the tendons, the reinforcement of the PS (prestressed) concrete bridges in use, and the sequencing of simple girders. The external tensioning method for PS concrete girder is determined by the installation method of anchoring and holding anchorage of tension member disposed outside PS concrete girder. In addition, in recent years, in order to prevent the loss of tension and to raise the grade of the bridge in the PS concrete bridges, new anchorages and supports for the introduction of external tension are being installed in advance.

The most common method for introducing external tension to reinforce the PS concrete girder bridge in use is to fix the steel fixing device with anchor bolts or steel rods to the perforated PS concrete girder (Domestic Application 10-2002-0040223, 10-2002-0058112, 20-2000-0020363, 20-2001-0004505, 20-2001-0035616. In order to increase the friction between the girder and the fixing device, epoxy mortar is sometimes inserted into the contact surface (domestic application 02-2002-0017224), and external tension is introduced into the slab by the fixing device attached to the cross beam or girder Application 20-2002-003689 has also been developed. However, the punching of PS concrete girders by anchor bolts or steel rods damages the girder itself. In order to solve this problem, a simple support is inserted into the lower flange (domestic application 10-2003-0069030), and the larger the deflection, the higher the reinforcing effect. In addition, for the new bridges, steel blocks (domestic application 10-2001-0060681) are installed in the PS concrete girder to fix and support the external tension material at the bottom of the flange of the girder for the introduction of external tension material. Box-shaped steel reinforcement plates for attachment of supports are also pre-installed on PS concrete girders (Domestic Application 10-2004-0009282, 10-2004-0017706).

The external tensioning method is becoming more important for the introduction of additional tension force, steel continuity of simple girder and retension to compensate and reinforce tension loss during use after the basic structure of PS concrete composite girder bridge is completed. However, this requires that the tensions introduced into the anchorage and support can be safely transferred to the PS concrete girder. In this method, the external tension is introduced into PS concrete girder by the bearing of the anchoring end by installing the anchor and support of external tensioning material in the prefabricated cross beam (domestic application 10-2004-0032551) reinforced by the existing connecting steel box. It is a method to introduce external tension in an efficient and safe way to PS concrete composite girder bridges by friction against the vertical force of the bending section.

External tension applied to PS concrete girders is very important for tension loss compensation, reinforcement of girders and sequencing of simple girders. However, there are many problems in the installation of conventional anchorages and supports, such as damage to the PS concrete girder and difficulty in the construction process for the bridge in use. This method of fixing the anchorage and support of external tension member to the reinforcing steel box of the prefabricated crossbeam is to solve the following problems in the existing bridge efficiently.

1.Prevention of damage to the girder caused by the drilling work to fix the anchorage and the support

2. Safe transmission to PS concrete girder with external tension introduced into anchors and supports

3. Securing the work space for introducing external tension

4. Introduction of External Tension to Composite Section of Girder and Deck Plates

5. Securing continuity of connected parts at internal points

1 is a perspective view of a typical continuous PS concrete composite girder bridge

2 is a layout view of the external tension material of the continuous PS concrete girder according to the present method

3 is a layout view of the external tensioning material at the fixing end of the present method

4 is a detailed view of the arrangement of the external tension member at the continuous internal points of the present method;

5 is a prefabricated prefabricated point gaborbo and components of the present method

6 is a prefabricated intermediate crossbeam and components of the bent portion of the present method

7 is a continuous internal point prefabricated point giraffe and components of the present method

[Figure 8] Reinforcement steel box of the prefabricated crossbeam connection fixed to the anchorage or support of the external tension member

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

10. External tension material anchorage

11.Fixed end prefabricated branch

12. Reinforcement steel box of girder connection of fixing point prefabricated robot

13. Reinforcement steel box of cross beam connection of prefabricated point

14. External tension member support

15. prefabricated middle street robo

16. Reinforcement steel box of girder connection of prefabricated middle girvo

17. Inside point prefabricated street

18. Reinforcement steel box of girder connection of interior point prefabricated robo

19. Reinforcement steel box of crossbeam connection of interior point prefabricated beam

20. External tension material

21. End reinforced PS concrete girder (domestic application 10-2004-0009282 or 10-2004-0017706)

22. Rebar

23. Horizontal shear or shear friction rebar for girder-floor integration

24. Weld Head Studs

25. Bolting Head Stud (Domestic Application 10-2003-0099610)

26. Bolts for bolting head studs

27. Bolted head stud (Domestic application 10-2004-0026479)

31. PS concrete girder 32. On-site casting point

33. On-site Middle Road 34. Pier

35. Placement middle floor plate 36. Placement point floor plate

37. Chair Unit

In general, a continuous PS concrete composite girder bridge having a lattice structure of the girder 31 and the cross beams 32 and 33 is configured as shown in FIG. 1. This method is a prefabricated crossbeam (11, which is equipped with PS concrete girder 21 (domestic application 10-2004-0009282 or 10-2004-0017706) where the fixing end of the internal tension member is reinforced with a steel box) 15, 17) (domestic application 10-2004-0032551) is to introduce the external tension as shown in Figure 2 used bridge. In this method, anchorages and supports of external tension members are fixed to reinforcing steel boxes of prefabricated crossbeams.

Details of the fixing end and the continuous point of Figure 2 are shown in Figure 3 and 4, respectively. The external tensioning material 20 anchorage 10 of FIG. 3 is fixed in advance to the connection reinforcing steel box 12 of the point gabo in the manufacturing step of the fixing end point gabor 11 as shown in FIG. Since the fixing end point gabor 11 is installed across the girder 21 as shown in FIG. 3, the external tension force introduced is transmitted to the girder with end bearing force. The support 14 of the external tensioning material 20 is fixed to the connecting box strong box 16 of the intermediate girder 15 installed in the bent portion as shown in Figure 6, or across the girder to the continuous inner point as shown in FIG. The installation point is fixed to the connection box steel box 18 of the robot 17 is embedded in the cross beam.

The support 14 of the external tensioning material 20 is to maintain the parabola in the vertical direction with respect to the axial direction so that the equal distribution load in the vertical direction on the cross beam. The anchorage 10 and the supporter 14 of the external tensioning material 20 fixed to the connection reinforcement steel box (12, 16, 18) of the prefabricated beams are as shown in Figure 8, depending on the position, in a simple or continuous overall span The slope of the external tension material is continuous.

The use of the external tensioning method of this method, in which the anchorage and the support of the external tension member are fixed to the prefabricated crossbeam reinforced by steel box, can be expected to have the following effects.

1. It does not damage the girders because no drilling work is required to fix the anchorages and supports.

2. The axial force of the external tension member is transmitted by acupressure at the point of connection between the point and the end of the girder so that no shear force is generated between the anchorage and the girder.

3. Supports fixed in parabolic form in the reinforcing steel box of intermediate crossbeams at bends in which the direction of the external tension material changes, generate vertically distributed loads in the connecting beams of the crossbeams, and the friction between the crossbeams and the girders is relatively large. The vertical force of the crossbeam can be transmitted safely to the girders.

4. It is possible to introduce tension in the section of the parent near the inner point of the continuous PS concrete girder by forcing the support to the point of continuous inner point, and to control the continuity of the continuous inner point.

5. External tension material is fixed and supported on the cross beam between girders to secure a wide working space.

6. It is possible to introduce the tension force on the composite section after the bottom plate is poured, so when the external tension is introduced for the purpose of reinforcement during use, the external tension can be introduced immediately without restriction such as demolition of the bottom plate and control of traffic volume. have.

Claims (1)

This method is to introduce external tension to the PS concrete girder or composite girder in the simple or continuous PS concrete composite girder bridge prefabricated girders and cross beams, The external tension member is fixed and supported in the fixing unit 10 and the supporter 14 that are embedded in the cross beams while being fixed to the reinforcement steel box of the prefabricated crossbeam. The fixing unit 10 of the external tensioning material 20 is fixed to the connection box steel box 14 of the fixing end point gabor 11, The support 14 for changing the direction of the external tension member 20 is a connection box of the connection box box 16 of the intermediate crossbeam 15 or the inner point of the continuum crossbeam 17 in the form of a parabola in the height direction with respect to the axial direction. Is fixed to 19, The tension force introduced into the cross beam by the external tension member 20 is caused by the bearing pressure of the girder end at the fixing end, and the bent portion of the cross beam-girder connection reinforcement steel box 16 of the prefabricated intermediate crossbeam 15 and the inner point crossbeam 17. Method to transfer to PS concrete girder or composite girder by vertical friction connection