KR20050094613A - External prestressing method to improve load-carrying capacity of concrete beam-and-slab deck bridge using curved saddles and supplementary anchorages - Google Patents

Abstract

Material deterioration factors and structural safety deterrents during long-term or short-term common use in prestressed concrete (PSC) and reinforced concrete (RC) girder bridges, and design loads that are less than current loads (e.g. DB-24) For the PSC girder bridge, the external tensioning method using steel wire or continuous fiber is used to improve the performance of the bridge with less than -18) or the bridge with common load capacity less than the design load. In the case of girder bridge, various construction methods such as vertical expansion method, steel plate attachment, carbon fiber sheet attachment and epoxy panel attachment are applied.

External tensioning method for the PSC and RC girder bridge of the present invention is different depending on the presence or absence of crossbeams, but in general, a plurality of curved tension guide guide birds are installed on the basis of the crossbeam position that is hypothesized, so as to transmit the tension force to the girder when the tension force is introduced. For the movable and fixed end fixing devices, the additional fixing device, which consists of not only the main fixing device but also the auxiliary fixing bracket, the auxiliary fixing steel rod, and the auxiliary fixing device of the tension member, is additionally installed from the extension line of the main fixing device. To compensate for the problems caused by the decrease in the adhesive strength of anchor bolts and adhesives, the auxiliary fixing device reduces the loss as much as possible, and induces the effect of reducing the number of anchor bolts required to eliminate local defects of the reinforcement body as much as possible. I do it. In addition, unlike the tension method employed in most existing methods and under the girder, in the present invention, by installing the bracket forming the tension guide guide saddle on the side of the girder in all cross-sections, the planned flood level of the cross-flow according to the reduction of the geometry space Not only does the reduction occur, but the increase in the fixed load is minimal, and the maximum load moment as well as the load capacity of the front end portion is enhanced by moving the positions of the fixed end and the movable end to the top of the point as much as possible.

Description

External prestressing method to improve load-carrying capacity of concrete beam-and-slab deck bridge using curved saddles and supplementary anchorages}

The present invention uses a curved tension guide saddle installed in a plurality of cross beam position in principle to transfer the tension force to the girder in equal distribution, and by additionally installing an auxiliary fixing device in addition to the main fixing device to minimize the loss of tension and to reduce the tension guide saddle By moving the bracket to the side of the girder, the reduction of the planned flood level of the cross-flow which occurs frequently in the RC girder bridge is not induced, and the increase in the fixed load is minimal and the maximum position is achieved by moving the positions of the fixed end and the movable end to the point. The present invention relates to an external tensioning method for reinforcement and performance improvement of PSC and RC girder bridges which enhances the load capacity of not only the bending moment but also the shear.

The conventional non-attached external tensioning method for the PSC girder bridge is reduced by installing a fixing device and introducing tension by forming a plurality of through holes in the width direction with respect to both ends of the girder or exposing the reinforcing bars at the ends. It is composed of reinforcing load capacity. In addition, it is known to reinforce the load-bearing performance by injecting a steel bar into the impression hole formed at the time of manufacture of the PSC girder and then introducing tension force to the steel wire disposed on the bottom of the girder or simply attaching a plurality of intermediate support brackets at arbitrary positions of the girder. .

However, the typical conventional method as described above is required to increase the construction cost and construction period by forming through-holes in the width direction at the both ends of the girder or exposing the reinforcing bars, and damage of the reinforcing rods is expected due to cutting of the end bars. If proper measures are not taken for the reinforcing bars, corrosion may occur. Therefore, the rigidity of the actual reinforced structure before reinforcement is lowered, which poses a problem that threatens the safety of the bridge. In addition, when the wire placed on the bottom of the girder is tensioned after simply passing through the tension member with the cable intermediate support or the intermediate support bracket, as shown in the figure below), the tension member is in many cases due to neglect of the anchorage management of the anchorage or the activity of the anchorage. Even if the problem of sagging occurs or the management of these is relatively strictly performed, in the case of intermediate supporting brackets or saddles arranged horizontally as shown in Fig. 2), the upward force at the inlet or the outlet (a) at both ends of the brackets or saddles is shown. In this case, it is difficult to expect the same attachment effect on the entire contact surface of the bracket or saddle because the deformation and activity of the bracket or birds are easily generated due to the concentration of stress and the action of the horizontal component in the region (a). If this is not taken into account since their peeling may occur A large decrease in tension effects is expected.

Therefore, in order to make up for the problems as shown in Figs. A) and b) above, the maintenance of re-tensioning in common is necessary, but it is not easy to regularly use tension facilities equipped with hydraulic devices. . As a countermeasure, it is important to reduce the deformation of the brackets constituting the fixed and movable end fixing devices as much as possible. For this purpose, in addition to the use of brackets with sufficient rigidity, the fixing unit of the tension member is provided by an auxiliary fixing device using an auxiliary fixing bracket. It is expected to prevent the reduction of tension caused by activities and to reduce the maintenance cost in the future, and to maintain the same curvature as that of the tension member arranged in a curve to prevent deformation, activity, or peeling of the horizontal support bracket or birds. It may be required to introduce the curved guide saddles having the above-mentioned problems and to effectively generate an upward force of an even distribution.

On the other hand, the conventional method described above focuses only on the bending reinforcement of the PSC girder bridge, and in the reinforcement of the RC girder bridge, a vertical expansion method or a simple straight type method that adversely affects a large increase in the fixed load or the planned flood level in the cross stream is As has been generally applied, the need for public development has been largely neglected. However, as the RC girder bridge, which is required to improve the performance of most of the bridge types in Korea, the traffic that exceeds the original design load is rapidly increasing with the development of the industry, and the rigidity is deteriorated due to the long-term use. It is widely known that the usability, such as cracking and sagging, as well as the bending and shearing safety are extremely degraded under the area, and the development of an appropriate structural reinforcement method corresponding to the PSC girder bridge is also urgent for the RC girder bridge.

Therefore, in order to reinforce PSC and RC girder bridges that have been aged or severely damaged, it is possible to exclude any damage to the target bridge or to provide a cause that may cause defects in the future. By effectively transmitting the external tension to the target bridge and greatly reducing the loss of tension, it is possible to obtain the performance improvement effect not only for PSC but also for bending and shearing of RC girder bridge, and to satisfy the reduction of maintenance cost. We will present the method technically.

The process of the reinforcement and performance improvement method of the PSC and RC girder bridges (1, 2, 3 of FIG. 1) according to the present invention for completing the technical problem of the present invention is a design load of less than the current pass-through load (e.g. DB-24) Tension members, main anchoring devices and supporting devices installed in the mold for design tensions determined in the preliminary structural calculation for bridges with bridges or bridges with common load capacity below the original design load, or for structures requiring significant performance improvement due to the occurrence of significant defects. It uses the rigidity of the fixing device, the curved guide saddle and the cross beam, and introduces it as an equally distributed upward force, and removes and finishes the hydraulic jack.

The configuration of the present invention will be described with reference to the accompanying drawings.

1 is a side view of the slab (1), mold (2) and cross beam (3) of the concrete structure reinforced by the reinforcement and performance improvement method according to the embodiment of the present invention for the simple (or continuous) PSC and RC girder bridge When the fixed stage fixing device 4, the movable end fixing device 5, and the cross beam 3, which exist at the end of the structure constituting the present invention, are present or curved, the curved length 1/4 and 3/4 points The guide saddles 6 and 7 and the half point (center) curved guide saddle 8 of the span are shown together with the tension member 9.

According to Figs. 2, 3, 4A and 4B according to Fig. 1, the fixing device of each of the fixed end and the movable end is fixed to the whole shaft of the structure (neutral shaft of the composite section) and the tension member fixing nut of the fixed end and the movable end 14-. 1) Place the surface of the fixing plate (10-1, 10-2) on the rear surface of the fixing plate (10-1, 10-2) about 5mm (typically, the thickness of the concrete cover is 50mm-100mm) and roughen the fixing plate (10-1). , 10-2) and the epoxy is injected between the concrete surface and fixed with anchor bolts 12 so that sufficient adhesion strength is expressed between them through a curing period of 1-2 days. In addition, at the same time as the fixed end and movable end fixing devices 4 and 5, the curved guide saddle sets 7, 8 and 9 as shown in FIG. 4A or 4B also have epoxy injection and guide saddles fixed after chipping. Installation of the anchor bolt 21 is in progress. In particular, the tension member 9 can be connected from the fixed end to the movable end in the outer mold one side (FIGS. 5A and 6A) or the inner mold both sides (FIGS. 5B and 6B) in which the cross beams 3 exist. Tension guide tube (FIG. 5A) made by the guide plate through hole 19-1 and the cross beam core hole 22 and the curved steel pipe (19-2 of FIGS. 4A and 4B) inserted in succession thereof. 5b or 23) of FIGS. 6a and 6b, wherein the tension member 9 to be used has a maximum dimension of 40 mm, a thickness of the curved steel pipe up to 2 mm, and an auxiliary fixing steel rod threaded at both ends. In consideration of the diameter of 50mm, the diameter of each hole including the horizontal beam core hole is up to 75mm, and the position of the through hole 19-1 of the guide plate is based on the height of the mold, the position of the neutral axis, and the profile of the tension member 9 accordingly. Change according to (Figures 5a and 5b or 6A and VAR) of FIG. 6B to allow the curved guide birds to be completed.

After the installation of the series of fixing apparatuses 4 and 5 and the guide saddles 6 and 7, as described above, the tension member 9 and the auxiliary fixing steel rods 13-1 and 13-2 are illustrated in FIGS. Steel rods 13-1 for assembling the brackets 11-1, 11-2, 11-3, 11-4 set in each fixing plate and fixing the fixing end fixing device 4 as in Fig. Anchor nut 14-2 is fastened to the anchor nut 14, and the anchor nut 14-1 for fixing the tension member is completely fixed for tension work in the movable end fixing device 5.

As shown in FIG. 1, the tension member guide pipes (FIGS. 5A and 5B or 23A of FIGS. 5A and 6B) located in the curved guide saddles 6, 7, and 8 in the bracket 11-1 of the fixed end fixing device are removed. The tension member 9 disposed up to the movable end fixing device 5 is fixed to the anchor nut 14-1 at the same time as the tension bracket 11-3 of the movable end fixing device 5 is completed and the tension is increased. After completion, it is extended to the auxiliary fixing bracket (11-4) to fix the rolled screw portion (14-3) with the anchor nut to prevent the reduction of the introduced tension force. When the tension of the tension member 9 is completed and the tension member 9 is anchored to the auxiliary fixing bracket 11-4 with an anchor nut 14-3, the main fixing bracket 11-3 of the movable end fixing apparatus 5 is fixed. And the auxiliary fixing steel bar 13-2 set on the auxiliary fixing bracket 11-4 are also fixed by the anchor nut 14-2. After checking the deformation or defect of each part bracket which may be generated when the tension member 9 is tensioned, and confirming that there is no defect, a protective cap is installed at the fixed end and the movable end fixing unit, and the tension member induction pipe ((FIG. 5A and FIG. Inject grease into 5b or 23) of FIG. 6a and 6b to prevent inflow of moisture or foreign matter in the future, and epoxy in the gap between the core hole 22 formed in the crossbeam 3 and the curved steel pipe 19-2. By injecting and curing, the cross beam 3 and the steel pipe 19-2 are integrated and finished.

The PSC girder bridge, which is reinforced and improved by the method of forming a local core hole of the tension member, the main fixing device and the auxiliary fixing device, the curved guide saddle, and the cross member which is the auxiliary member based on the above-described implementation, is a conventional non-adhesive type. The tension method completely eliminates the degradation of rigidity that may be caused by the lateral through-hole of the mold that bears substantial resistance to external loads or local damage caused by rebar exposure. It is expected to greatly improve the problems, such as reducing the tension effect caused by deformation due to local stress concentration caused by horizontal placement of intermediate brackets or birds. In addition, the fixed load increases by adopting a rigid and small fixing device in the RC girder bridge, compared to the bell type process, which is frequently applied in the existing RC girder bridge, or a simple straight type method such as carbon fiber sheet or panel series. It is expected that the tension position can be as close to the point as possible, so that not only the shear reinforcement effect that has been neglected in the past but also the substantial structural reinforcement and performance improvement effect on the maximum moment part will be greatly increased.

External tensioning method for reinforcing and improving the performance of PSC and RC girder bridges using local core hole of tension member, main fixing device and auxiliary fixing device, curved guide saddle and auxiliary member of horizontal beam according to the present invention described above The attachment tension method is expected to solve the loss factors such as stiffness due to local damage of exposed mold, sagging of tension material and local deformation of brackets or birds. In addition, there is no additional fixed load increase compared to the vertical expansion method or the simple straight type method, which is frequently applied in the existing RC girder bridge as well as the PSC girder bridge, and the shear that has been neglected by moving the tension member to the branch part. In addition to the reinforcement effect, it is expected that the substantial structural reinforcement effect and performance improvement effect on the maximum moment portion will be greatly increased.

1 is a side view showing a conceptual diagram and a reinforcement example of the PSC and RC girder bridge according to the present invention.

2 is a plan view, front view and side view of the tension member fixing end fixing device according to FIG.

3 is a plan view, front view and side view of the tension member movable end fixing device according to FIG.

FIG. 4A is a conceptual view illustrating installation of representative guide birds installed in a non-girder bridge or crossbeam position where no cross beam is present in PSC and RC girder bridges according to FIG. 1.

FIG. 4B is a conceptual view illustrating the installation of representative guide birds installed in the girder bridge or the crossbeam position where the cross beams exist in the PSC and RC girder bridges according to FIG. 1.

5A is a plan view, a front view, and a side view detail of a guide saddle installed at one side crossbeam portion in a center portion outer mold of a span of a PSC and RC girder bridge span according to FIGS. 1 and 4B.

5B is a plan view, a front view, and a side view detail of guide saddles installed at both side crossbeams in a medial inner mold of the PSC and RC girder bridge spans according to FIGS. 1 and 4B.

6A is a plan view, a front view, and a side view detail of a guide saddle installed in one side crossbeam portion between a center portion and an end portion of an outer mold of a PSC and RC girder bridge according to FIGS. 1 and 4B.

6B is a plan view, a front view, and a side view detail of guide saddles installed in both side beam portions between a span center portion and an end portion in the PSC and RC girder bridge inner mold according to FIGS. 1 and 4B.

* Explanation of symbols for main parts of the drawings

1, 2, 3: concrete slab (1), mold (2), cross beam (3),

4: fixed stage fixing device,

5: movable end fixing device,

6, 7: curved guide saddle between the point and the span center,

8: curved guide saddle in the middle of the span,

9: polyethylene cloth tension material

10-1, 10-2: fixed end fixing plate 10-1 and movable end fixing plate 10-2,

11-1, 11-2, 11-3, 11-4: main fixing brackets 11-1, 11-3 and auxiliary fixing brackets 11-2, 11-4 set on the fixed and movable end fixing plates. ),

12: anchor hole for fixing the fixed and movable end fixing plate,

13-1, 13-2: auxiliary fixing steel bar 13-1 of the fixed end and auxiliary fixing steel bar 13-2 of the movable end,

14-1, 14-2, 14-3: tension member fixing nut (14-1), steel rod fixing nut (14-2) of the auxiliary fixing device, tension member auxiliary fixing nut (14-3),

15: bottom plate of the guide saddle,

16: side plate of guide saddle,

17: side brackets of guide birds,

18: tension guide plate of the guide birds,

19-1, 19-2: through-hole 19-1 and curved steel pipe 19-2 of the guide plate,

20: guide bracket side plate bottom plate,

21: anchor hole for fixing the saddle saddle,

22: gorbo core hole,

23: Tension guide tube formed by plate through hole and curved steel pipe.

Claims (6)

Reinforcement and performance improvement of PSC and RC girder bridges by non-attached external tension according to the method of arranging the tension material in a curved manner by forming core core hole and auxiliary fixing device of tension material, curved saddle, and cross beam. Way. In accordance with claim 1, an auxiliary fixing bracket is installed on each of the fixed end and the movable end fixing device, the tensioning material is fixed in the main fixing bracket of the movable end fixing device, and then the tensioning material screwed to the auxiliary fixing bracket is extended to the anchor nut. Method of reinforcing and performance improvement of the bridge to be settled. In accordance with claim 1 and 2, a pair of auxiliary fixing steel rods screwed at both ends of the fixed end and the movable end fixing device are integrated with anchor nuts by integrating the main fixing bracket and the auxiliary fixing bracket with anchor nuts. Method of reinforcing and improving the bridge to prevent activity and deformation. Bridge reinforcement by means of curved guide saddles formed by forming through holes in the plate in accordance with the profile of the tension member arranged in a curved manner in accordance with claim 1 and changing the hole position from the longitudinal direction of the mold to the curve. And how to improve performance. Reinforcement of the bridge by inserting a steel pipe having the same curvature as the curvature of the hole and forming a tension guide tube inside the guide plate in which the hole is formed in accordance with claim 1 and 4. And how to improve performance. The tension member which is continuously curved from the fixed end to the movable end fixing device by the cross beam core hole formed in the cross beam position and the curved steel pipe inserted therein in accordance with claim 1, 4 and 5. Method of reinforcing and performance improvement of the bridge by the.