JP3420719B2 - Prestressed concrete girder using external cable - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prestressed concrete girder using an external cable such as a bridge. 2. Description of the Related Art Concrete bridges are frequently used as bridges for railways and roads because of their low noise and non-rust properties. Especially for long span bridges, prestressed concrete bridges are excellent, and various types of prestressed concrete bridges are employed. However, as the span becomes longer, the cross section of the girder becomes larger, the girder's own weight inevitably increases, and the amount of PC steel increases. Also, structures such as piers become larger, causing problems in seismic resistance and economic efficiency. . As one of the solutions, a PC cable, which was conventionally housed in a girder concrete section, is disposed outside the concrete section, and the web and floor slab concrete are reduced in thickness to reduce the weight. It is being done. FIG. 12 is a schematic perspective sectional view of a prestressed concrete girder using an external cable. A supporting and deflecting projection (deviator) 5 is arranged in an inner box-shaped space of a box-shaped concrete girder composed of an upper floor slab 21, a web 22, and a lower floor slab 23, and the PC cable 2 is stretched outside the concrete cross-section of the girder. The structure supports the bridge body via the deviator 5 and introduces prestress. As described above, the PC cable, which has been conventionally arranged in the web or the floor slab, is taken out of the concrete section, whereby the member thickness can be reduced, and the weight of the girder can be reduced. In FIG. 12, 24 is a cross beam, and 4 is a pier. However, in the prestressed concrete girder 1 using the external cable, the PC cable 2 is arranged outside the concrete section, and the contact point between the bridge and the PC cable 2 is limited to both ends of the girder 1 and the deviator 5. Therefore P
C-cable has low friction with concrete and pre-stress can be effectively introduced. However, since there is no adhesion between PC cable and bridge body, bending fracture resistance is small especially at the part where bending moment is large near the center of the span. However, it has been pointed out that it is necessary to increase the amount of PC steel to compensate for the problem, and that when cracks occur, they are not dispersed but concentrated. [0006] The present invention has a small cross-section, is lightweight, has a bending fracture resistance not inferior to that of a conventional prestressed concrete girder with a built-in cable, without increasing the amount of PC steel. An object of the present invention is to develop a prestressed concrete girder using an external cable having a structure in which harmless dispersed cracks are formed without concentrating even if cracks occur. SUMMARY OF THE INVENTION The present invention relates to a prestressed concrete girder in which a PC cable is disposed outside the concrete section of the girder, the total length between the deviators along the concrete surface of the PC cable after the introduction of the prestress. Wataru
A prestressed concrete girder using an external cable is characterized in that a portion to be buried is buried in a post-clad coated concrete, and the post-clad coated concrete is adhered to and integrated with the girder concrete. [0008] Embodiments of the present invention will be described below with reference to the drawings. FIG.
Is a prestressed concrete girder using an external cable 1
FIG. Girder 1 supported on abutment 3 and pier 4
The PC cable 2 bent down from the tension fixing ends at both ends applies bending force to the spar via two deviators 5 and introduces prestress into the spar concrete.
The part of the PC cable 2 located outside the girder concrete section between the two deviators 5 is pre-stressed and then buried in the post-cast covering concrete 6 by casting. This post-cast concrete 6 is a girder bottom concrete 7
And integrated. FIG. 2 is a detailed view of a portion A in FIG. 1. The deviator 5 is provided with a hole 8 through which the PC cable 2 penetrates, and the PC cable 2 continuous from the fixing ends at both ends of the girders is disposed therein. ing. The bent portion of the PC cable 2 is covered with a polyethylene tube 9 for rust prevention. The part buried in the post-coated concrete 6 between the deviators 5 and 5 is left uncovered in a bare state to enhance the adhesion performance with the post-coated concrete 6, and the PC cable 2 is buried in the post-coated concrete 6. When the grout is applied to the inside of the polyethylene pipe 9 at the bent portion of the PC cable 2 by a method of preventing rust of the cable by
It is preferable to cover the C cable portion with a sheath that communicates with the polyethylene pipe 9, inject grout over the entire length, and bury the grout in post-coated concrete to improve the rust prevention effect. FIG. 3 is a view taken in the direction of arrows BB in FIG. 1 and shows the tension fixing ends at both ends of the box girder. 4 is a cross-sectional view of the deviator section as viewed in the direction of arrows CC in FIG. 1, and FIG. 5 is a cross-sectional view as viewed in the direction of arrows DD in FIG.
The C cable 2 is shown. FIG. 6 is a detailed view of a portion E in FIG. 4, in which the PC cable 2 is inserted into a hole 8 embedded in a deviator 5 projecting from the lower slab concrete 7. FIG. 7 is a detailed view of a portion F in FIG. 5, in which the PC cable 2 is embedded in the post-cast concrete 6, and the post-cast concrete 6 is integrated with the lower slab concrete 7. FIG. 8 is a side view of a cable system suitable for applying the present invention, and is a side view showing an example of a PC strand aggregated cable. The end of the cable is shown in FIG.
−G As shown in the view of the arrow G, each PC is provided with a wedge 14 divided into two in a tapered hole formed in the steel anchor head 11.
A type in which the strand 13 is fixed, and a known cable system may be used. [0012] If several portions of the cable system are buried in the post-cast concrete, several bulging portions are provided so that the concrete wraps between the PC strands and the adhesion between the concrete and the PC strands becomes more reliable. As shown in FIG. 10 as viewed from the direction of arrows HH in FIG.
Each PC strand 13 is dispersed with the separator 15 interposed. FIG. 11 is a view taken on line II of FIG.
By squeezing the front and rear with the press ring 16, the expanded portion can be easily formed. In the above embodiment, a simple girder type bridge girder has been described. However, in the case of a continuous girder, the outer cable at a location where positive and negative bending moments are generated is buried in post-coated concrete and adhered to the concrete. It is more effective. The prestressed concrete girder using an external cable in which the PC cable of the present invention is disposed outside the concrete section of the girder is obtained by embedding the PC cable in a post-cast covering concrete after introducing prestress. By attaching and integrating with concrete, it can be made a lightweight girder that is not different from the conventional external cable concrete girder, and moreover, it requires only about the same amount of steel material as the conventional cable built-in concrete girder, it is economical, It has become possible to provide a prestressed concrete girder having bending fracture resistance.
Also, if grout is injected into the sheath of the buried portion that communicates with the polyethylene pipe of the PC cable bending part, it is possible to check the filling state of grout by injecting grout before constructing the coated concrete. And increase the reliability of grouting work,
Sheath and grout and double and triple anticorrosion means improve durability and realize highly reliable prestressed concrete girder. Furthermore, since the bridge body becomes lighter, it is also possible to reduce the foundation costs of the piers and the like, and the effect is immeasurable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a prestressed concrete girder using an external cable. FIG. 2 is a detailed view of a portion A in FIG. FIG. 3 is a view taken in the direction of arrows BB in FIG. 1; FIG. 4 is a view taken in the direction of arrows CC in FIG. 1; FIG. 5 is a view as seen in the direction of the arrows D in FIG. 1; FIG. 6 is a detailed view of a portion E in FIG. 4; FIG. 7 is a detailed view of a portion F in FIG. 5; FIG. 8 is a side view of the PC cable system. FIG. 9 is a view taken in the direction of arrows GG in FIG. 8; FIG. 10 is a view taken along the line HH of FIG. 8; FIG. 11 is a view taken along the arrow II in FIG. 8; FIG. 12 is a perspective sectional view of a prestressed concrete girder using an outer cable. [Description of Signs] 1 Prestressed concrete girder using outer cable 2 PC cable (outer cable) 3 Abutment 4 Pier 5 Deviator 6 Post-cast concrete 7 Lower floor concrete 8 Hole 9 Polyethylene pipe 11 Anchor head 12 Support plate 13 PC Strand 14 Wedge 15 Separator 16 Pressing ring 21 Upper floor plate 22 Web 23 Lower floor plate 24 Cross beam

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) E01D 2/00-2/04 E01D 1/00 E01D 11/00-11/04 E04B 5/02 E04C 2 / 06

Claims (1)

(57) [Claim 1] In a prestressed concrete girder in which a PC cable is arranged outside a concrete cross section of a girder, a portion extending over the entire length between deviators along a concrete surface of the PC cable after introduction of prestress. A prestressed concrete girder using an external cable, wherein the pre-stressed concrete girder is buried in a post-clad coated concrete, and the post-clad coated concrete is adhered to and integrated with the girder concrete.