JPS5817773Y2 - Prestressed concrete girder for road bridge - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a prestressed concrete girder installed between the support legs of a road bridge.

Prestressed concrete girders are generally manufactured using a pretension method or a post tension method, but conventional prestressed concrete girders have the disadvantage of being difficult to construct when constructing expansion and contraction devices at road joints.

In other words, in a prestressed concrete girder, the upper surface of the girder is formed at the same height at both longitudinal ends and the middle part thereof, but when constructing an expansion device, the height of the expansion device or the height below the expansion device or It is necessary to provide a notch at the road joint depending on the length of the anchor bar that will protrude rearward, and usually a prestressed concrete girder a is cut out at the top of both ends of the upper flange b, as shown in Figure 8. It is used.

In this prestressed conchnaut girder a, since the thickness C at both ends of the upper flange a is thin, when an excessive load is applied from the road surface via the expansion and contraction device built on top of the upper flange a,
There is a risk that this upper flange b may be damaged, making it difficult to construct a telescoping device with high load-bearing strength.

In view of these points, the present invention has a step portion lower than the top surface of the girder formed at the longitudinal end of the girder, a plate-shaped step surface member installed in this step portion, and a dowel bar on the step surface member. It is an object of the present invention to overcome the above-mentioned drawbacks of the conventional method by providing a prestressed concrete girder provided with a prestressed concrete girder and constructing an expansion and contraction device at a road joint using this stepped surface member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to the drawings.

1 is a prestressed concrete girder with a single-shaped cross section that is installed between the support legs of a road bridge, and tension steel members 5 are embedded in both the upper flange 2 and the lower flange 3 that are connected to the upper and lower parts of the web 9. ing.

The upper flange 2 of the prestressed concrete girder 1 has a stepped portion 6 lower than the girder top surface 4 formed at both ends in the elongated direction, and a plate with a cross-section shaped like an ellipse is provided on the bottom surface and vertical surface of the stepped portion to cover the bottom surface and the vertical surface. A stepped surface member 7 having a shape is fixed.

The stepped surface member 7 has a length l of the bottom side 7a of about 150 to 300 mm, and a height h of the vertical side 7b of about 50 mm.
Anchor reinforcements 8, 8, approximately 150 mm in length and protruding from the back side of the bottom and vertical sides, are buried in the concrete of the prestressed concrete girder 1.

The step surface member 7 has a plurality of dowel bars 10 projecting upward from the bottom side 7a, and a plurality of through holes 11.11 are formed at the bottom side 7a.

When manufacturing the prestressed concrete girder 1, if the pretension method is used, as shown in FIG. A formwork 13 to which step surface members 7 are attached is installed at both ends of the fixing plate 12b on the right side in the drawing (hereinafter, the left and right positional relationship is as in the drawing).

) is connected to a movable plate 15 via an adjustment bolt 14.

The tensioned steel material 5 has one end fixed to the fixed plate 12a on the left side, the other end passes through the formwork 13, and is further fixed to the fixed plate 12a on the right side.
2b and is fixed to the movable plate 15.

Next, the movable plate 15 is moved to the right by the adjustment bolt 14 to apply tension to the tension steel material 5, and then the formwork 13
Concrete 16 is poured within.

Concrete strength and concrete 16 and tension steel 9
After the adhesion strength reaches a predetermined value, the adjusting bolts 14 are loosened, the formwork 13 is removed, and the tension steel members 5 are cut to obtain the prestressed concrete girder 1 shown in FIG.

When using the boss tension method, a sheath with tension steel inserted through it is fixed in the formwork, concrete is poured, and the formwork is removed after the concrete has hardened.

After that, tension is applied to the tension steel material, concrete, resin, etc. are injected into the sheath, and the tension steel material is fixed.

Next, a road joint expansion/contraction device for a road bridge to which the prestressed concrete girder 1 described above is applied will be explained.

As shown in Figures 3 and 4, 1 is a prestressed concrete girder installed on the support leg 17 of a road bridge, and filler concrete 18 is placed between the girders, and the prestressed concrete girder 1 is Opposing step surface member 7
, 7, an expansion and contraction device 19 is installed.

In the expansion/contraction device 19, a flexible expansion/contraction plate 21 having a U-shaped cross section is bonded by baking to the opposing inner surfaces of opposing corrugated end plates 20 and 20.
A bottom plate 22 is fixed to the lower surface of the corrugated end plate, and a weir plate 23 erected on the bottom side 7a of the step surface member 7 is fixed to the back surface of the corrugated end plate 20. An anchor member 24 protruding from is connected to the dowel reinforcement 10 of the step surface member 7 together with the reinforcing reinforcement 25 and the through reinforcement 26,
Post-cast concrete 27 is placed on the back of the corrugated end plate 20.

28 is pavement. In the prestressed concrete girder 1, both ends of the girder are covered by step surface members 7 to increase the strength, so even if an excessive load is applied via the road surface expansion/contraction device 19 when a vehicle passes, Will not be damaged.

In addition, when constructing the expansion and contraction device 19, a step portion 6 lower than the top surface of the girder is formed on the prestressed concrete girder 1,
Since the step surface member 7 is fixed to the step, there is no need to form a new notch.

Moreover, since the surface of the bottom side 7a of the step surface member 7 is smooth, there is no gap between the weir plate 23 and the bottom side, so that concrete leaks when pouring concrete 27 is poured. will not occur.

In addition, since the end of the prestressed concrete girder 1 is formed into a step with a predetermined depth by the step surface member 7, there is no difference in depth between each girder, and therefore the top of the step surface member is Since the height of the upper edge of the vertically installed weir plate 23 is approximately constant, the corrugated end plate 2 connected to the upper part of the weir plate
0 height adjustment becomes easy, allowing for highly accurate construction.

Furthermore, the corrugated end plate 20 can be reliably fixed to the road joint by connecting the anchor member 24 protruding from the back side to the dowel bar 10 of the stepped surface member 7, so that it can withstand the load of the expansion and contraction device 19. Strength is improved.

Furthermore, since a plurality of through holes 11 are formed in the stepped surface member 7, the prestressed concrete girder 1 and the post-cast concrete 27 are connected with the same concrete, and the dowel reinforcements 10 and Therefore, the bond strength between the prestressed concrete girder and the post-cast concrete is enhanced.

In addition, although the through-hole 11 was opened in the step surface member 7 in the said Example, the through-hole 11 may not be provided in some cases.

The step surface member is not limited to the step surface member 7 having the above-mentioned cross-sectional shape, and its shape can be changed as appropriate depending on the type of expansion/contraction device constructed at the road joint.

For example, as shown in FIG. 5, a pair of parallel vertical end plates 2
9 and 29, and a telescopic member 30 is fixed to the opposing inner surfaces of the telescopic device 31, the cross section U
Preferably, a step surface member 32 in the shape of a letter is applied.

In this case, the vertical end plate 29 is fixed to the vertical side portion 32a of the step surface member 32 fixed to the prestressed concrete girder 1.

The mounting strength of the two vertical end plates is increased by the step surface member 32, and the post-cast concrete 27 is attached to the step surface member 32.
Since it is firmly connected to the prestressed concrete girder 1 through the , an expansion and contraction device with high load-bearing strength can be obtained.

Furthermore, the step surface member does not necessarily need to be fixed so as to completely cover both the bottom and vertical surfaces of the step of the prestressed concrete girder, but only the bottom surface of the step as shown in Figure 6. The flat step surface member 33 may be fixed.

Furthermore, as shown in FIG. 6, flexible seal plates 35 are baked and bonded to the upper surfaces of the substrates 34, 34 on both sides, and anchors are attached to the road joints, which protrude from the lower surfaces of the substrates 34, 34. It is also possible to construct a horizontal expansion/contraction device 36 by embedding the member 24 in post-cast concrete 27.

The prestressed concrete girder 1 has various step surface members fixed by cutting out the upper part of the upper flange 2, but as shown in FIG. At a specified interval from the end (150 to 300
mm) may be removed and the step surface member 36 may be fixed.

In this case, since the bottom part 36a of the stepped surface member 36 is deeper than the upper surface of the upper flange 2, it is possible to construct an expansion and contraction device with high load-bearing strength, and the thin layer part of the upper flange 2 is Therefore, damage due to excessive load will not occur.

Of course, not only the end of the upper flange 2 but also the web 9
It is also possible to remove up to the top of the step to form an even deeper step.

Further, the cross-sectional shape of the prestressed concrete girder may be other than the above-mentioned ■ shape, such as a T-shape or a box shape.

As described above, according to the prestressed concrete girder according to the present invention, the strength of the end of the girder is increased because the step surface member is fixed to the step lower than the top surface of the girder formed at the longitudinal end. Therefore, even if an excessive load is applied from the road surface through the expansion device, the prestressed concrete girder will not be damaged, increasing the load-bearing strength of the road joint, and also preventing the formation of stepped shapes at the ends of the girder. It is easy to use, and since the dowel bars are provided on the step face member, the connection between the post-cast concrete that fixes the expandable member and the step face member and the press rest concrete girder is improved. Because the anchor members of the present invention can be connected, an excellent effect can be obtained in that it is easy to construct a telescoping device with high load-bearing strength.

[Brief explanation of drawings]

1 to 6 illustrate embodiments of the present invention, FIG. 1 is a perspective view showing a prestressed concrete girder with some parts omitted, and FIG. 2 shows a method of manufacturing a prestressed concrete girder with some parts omitted, Figure 3 is a partially cutaway front view, Figure 3 is a plan view of an example of a road joint expansion and contraction device before pouring concrete, Figure 4 is a sectional view of the same, and Figures 5 and 6 are both A sectional view showing another example of the road joint expansion/contraction device, Fig. 7 is a perspective view showing other presses 1 to rest concrete girders partially omitted, and Fig. 8 is a conventional prestressed concrete girder partially omitted. FIG. 1... Prestressed concrete girder, 2...
...Top flange, 3...Bottom flange,
4...Girder top surface, 5...Tensile steel material, 6...
...Stepped section, 7, 32, 33, 36...
... Stepped surface member, 9... Web, 10...
... Gibel muscle, 11... Through hole.

Claims (1)

[Scope of utility model registration request] At the top of the web, flanges in which tension steel members are buried in the longitudinal direction are installed at predetermined intervals, and at both ends of the girder, steps lower than the top surface of the girder are formed, and the bottom or bottom and vertical surfaces of the steps are plate-shaped. A prestressed concrete girder for a road bridge, characterized in that a step face member is fixed and a dowel bar is erected on the step face member.