JP2008025221A - Elevated structure constructed by jointing pier stud of pc structure and steel box girder together - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elevated structure which has high structural reliability imparted thereto at a joint portion between a pier stud as a lower structure and a horizontal beam as a super structure, and can be constructed in a relatively short construction period. <P>SOLUTION: The elevated structure is formed of the pier stud 20 of a prestressed structure, which is obtained by stacking up cylindrical precast blocks 21 each having insertion holes for insertion of reinforcements and prestressing bars 22, inserting the reinforcements and the prestressing bars into the insertion holes, respectively, and pouring grout into the insertion holes, and the steel box girder 10. Then a steel annular body 14a arranged on a lower surface of the steel box girder is fitted onto an upper edge of the pier stud, and the prestressing bars are projected upward from the upper edge of the pier stud to be inserted into predetermined locations of the steel box girder, followed by anchoring upper edges of the prestressing bars to the steel box girder by means of anchorage devices 26, to thereby joint the pier stud of the PC structure and the steel box girder together. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an elevated structure, and more particularly to an elevated structure in which a steel box girder and a PC structure pedestal are coupled.

  Intersections are becoming more and more three-dimensional as a measure for facilitating traffic in urban areas and as a business related to urban regeneration. In the construction of elevated structures in such urban areas, the work zone is narrow and rapid construction is required. Therefore, the superstructure is composed of steel floor slab box girder, etc. As a shaft structure), many structures that connect these superstructures and substructures have been proposed.

  For example, Patent Document 1 proposes a composite pier that uses a reinforced concrete structure or a steel-reinforced reinforced concrete structure as the pier substructure, and uses steel cross beams and girders as the superstructure. The main bars protrude from the top end of the pedestal and are inserted into the steel horizontal beam, and the main bars protruding from the upper end surface of the steel horizontal beam are fixed with nuts.

  However, as in Patent Document 1, when the pedestal is made of a different structure or material such as a concrete structure and the cross beam is made of steel, it is designed so that the force is smoothly transmitted at the joint. It is difficult, and sufficient structural reliability cannot be obtained simply by fixing a reinforcing bar inserted through a steel cross beam with a nut.

  Moreover, in order to shorten the construction period of the pedestal and the underground foundation as the substructure, Patent Document 2 describes a method of continuously and integrally constructing the pedestal and the underground foundation. In this method, an underground press-fit blade is attached to the reference block, a cylindrical precast block is stacked on the reference block and sequentially connected with a PC steel rod, and the soil in the block and stacking of the cylindrical precast block are repeated. Press the block stack into the ground to reach the support base. Then, in order to form ground structures such as pedestals, the stacking of cylindrical precast blocks is repeated, the reinforcing bars are inserted through the reinforcing bar insertion holes of the stacked blocks, and the reinforcing bar insertion holes are filled with grout. And fix it.

Patent Document 2 is effective in terms of shortening the work period of the pedestal and underground foundation, but there is no description about a structure in which a bridge girder as an upper structure is coupled to a pedestal as a substructure. The problem of enabling smooth transmission of force in the section cannot be solved.
JP-A-5-79017 JP-A-8-4021

  In view of the current situation as described above, the problem of the present invention is that the structural reliability of the joint portion between the pedestal as the lower structure and the cross beam as the upper structure is high, and the construction is performed in a relatively short construction period. It is to provide an elevated structure capable of.

  In order to solve the above problems, in the present invention, a plurality of cylindrical precast blocks having insertion holes for reinforcing bars and PC steel rods are stacked and integrally connected by reinforcing bars and PC steel rods respectively inserted into the insertion holes. A prestressed pedestal column and a steel box girder are provided, and a steel annular body provided on the lower surface of the steel box girder is fitted to the upper end of the pedestal column. A steel bar is projected upward and is inserted into a predetermined part of the steel box girder, and the upper end of the PC steel bar is fixed to the steel box girder with a fixing tool, so that the PC structure leg and steel box girder are fixed. And an elevated structure is provided.

  In the elevated structure of the present invention, the PC steel rod of the prestressed reinforced concrete structure pedestal as the lower structure is inserted into the steel box girder and fastened with the fixing tool, so the pedestal and steel box girder are securely connected Combined with Furthermore, the steel box girder ring is fitted to the top of the pedestal, so the force from the steel box girder is smoothly transmitted from the ring to the top of the pedestal, and the joint is structurally reliable. Will be expensive.

  Hereinafter, an elevated road will be described as an embodiment of the elevated structure of the present invention with reference to the accompanying drawings, but the present invention is not limited to this.

The elevated road 1 of the present invention is constructed by connecting a steel box girder 10 as shown in FIG.
The steel box girder 10 has a main part composed of an upper flange 11, both webs 12, a lower flange 13 and an annular body 14, and all of these main parts are made of steel.
The upper flange 11 is provided with a horizontal rib 11b and a vertical rib 11c on the back side of the floor slab plate 11a, and a ground cover 15 and a rail 16 are fixed to both sides of the floor slab plate 11a. Both webs 12 are integrally formed on the back side of the floor slab plate 11 so as to extend vertically downward, and a lower flange 13 is provided at the lower end thereof in the horizontal direction. The annular body 14 has a hood 14 a that protrudes from the lower surface of the lower flange 13 and an upper portion 14 b that extends to the upper surface of the lower flange 13. A steel pipe 17 having a smaller diameter is integrally fixed on the lower flange 13 inside the upper portion 14 b of the annular body 14.

Next, the pedestal 20 is formed by a PPRC structure (Precast Prestressed Reinforced Concrete). The PPRC structure is a conventional structure using a cylindrical block 21 made of precast reinforced concrete. The cylindrical block 21 has a reinforcing bar insertion hole (not shown) and a PC steel rod insertion hole (not shown), respectively. A plurality of cylindrical blocks 21 are stacked, the PC steel rod 22 is inserted into the insertion hole, a tensile force is introduced into the PC steel rod 22, and the plurality of cylindrical blocks 21 are integrated, and a grout material ( By repeating the above-described process of injecting (not shown), all the cylindrical blocks 21 are stacked, and then a reinforcing bar (not shown) is inserted through the insertion hole and a grout material (not shown) is injected. It is what is done.
In the conventional structure, the PC steel bar 22 is fixed to the upper end of the cylindrical block 21 by a fixing tool. However, in the elevated road 1 of the present invention, as shown in FIG. It protrudes upward from the upper end of the block 21 and is used for coupling with the steel box girder 10.

  FIG. 2 is a cross-sectional view of a joint portion between the steel box girder 10 and the pedestal 20. In this joint structure, the hood 14 a of the steel box girder 10 is fitted to the outer periphery of the upper end portion 21 a of the cylindrical block 21. Then, the upper end portion of the PC steel rod 22 is inserted through a through hole 13 a provided in the lower flange 13. The upper end portion of the PC steel rod 22 is further extended upward and passed through a sheath tube (not shown), and a ring-shaped plate 18 provided on the upper portion 14 b of the annular body 14 and the small-diameter steel tube 17. Is inserted. In the gap between the upper end portion 21a of the cylindrical block 21 and the lower flange 13, and the gap between the upper end portion 21a of the cylindrical block 21 and the hood 14a of the steel box girder 10, a filler 19a such as a non-shrink mortar, 19b is injected. Further, concrete 25 is filled between the upper portion 14 b of the annular body 14 and the small diameter steel pipe 17. When the fillers 19a, 19b and the concrete 25 are sufficiently hardened, a tension structure is introduced into the PC steel bar 22 and fixed by the fixing tool 26, whereby the steel box girder 10 and the pedestal 20 are combined. Is done.

  As described above, after the steel box girder 10 and the pedestal column 20 are coupled and a predetermined number of steel box girder units are connected in the extending direction of the road, asphalt pavement is performed on the floor slab plate 11a. Elevated road 1 is constructed. As a result, it was possible to rapidly construct a three-dimensional road construction in a narrow place such as an intersection without occupying a wide work zone. Moreover, the effect which suppresses the residual displacement of a steel box girder is acquired by the tension force introduce | transduced into the PC steel rod of a pedestal. Furthermore, the steel box girder annular body is fitted to the upper end of the pedestal, so the force from the steel box girder is smoothly transmitted from the annular body to the upper end of the pedestal, and the joint has high structural reliability. Become a thing.

<Experimental result>
Next, the test results of the proof stress of the joint between the pedestal made of prestressed reinforced concrete and the steel box girder constituting the elevated structure of the present invention will be described below.
In the experiment, the joint between the pedestal and the steel box girder was formed at a scale of 1 / 4.5 scale, the horizontal load was repeatedly applied from the pedestal side, and the displacement was measured. The result is shown in Fig. 3. It was shown as a curve diagram. For horizontal loads up to the horizontal strength of the pedestal, the steel hood, the PC steel bar, and the reinforced concrete pedestal behave as one body, and if a load exceeding the horizontal strength of the pedestal is continuously loaded, The integral behavior of the box girder and the pedestal becomes difficult, causing stress concentration on the PC steel bar and destruction of the joint concrete.
From the experimental results, the steel box girder and the top of the pedestal column are fastened together with a PC steel rod, and the hood of the steel box girder is fitted to the top of the pedestal column so that the force from the steel box girder is It was found that the steel box girder and the pedestal behaved as a unit, smoothly transmitted to the upper end of the pedestal.

It is a perspective view before the steel box girder and pedestal which comprise an elevated road are combined. It is sectional drawing of the connection part of a steel box girder and a pedestal. It is the load-displacement curve figure obtained from the proof stress experiment with respect to the connection part of a steel box girder and a pedestal.

Explanation of symbols

1 Elevated road (elevated structure)
10 Steel box girder 14a Hood (annular body)
20 pedestal 21 cylindrical block 22 PC steel bar 26 fixing tool

Claims (1)

A plurality of cylindrical precast blocks having insertion holes for reinforcing bars and PC steel bars are stacked, and a prestressed pedestal unit integrally connected by reinforcing bars and PC steel bars respectively inserted into the insertion holes, and a steel box girder And
A steel annular body provided on the lower surface of the steel box girder is fitted to the upper end of the pedestal column, and a PC steel bar protrudes upward from the upper end of the pedestal column, so that a predetermined location of the steel box girder An elevated structure in which the PC structural pedestal and the steel box girder are combined by being inserted into the PC and the upper end of the PC steel bar fixed to the steel box girder with a fixing tool.

Images