JPS584004A - Construction of prefabricated prestressed steel beam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] A method for constructing a prestressed steel girder when constructing a bridge using a steel girder, in which the prestressed steel girder is created in advance as a plurality of prefabricated blocks, and these blocks are erected. This invention relates to a method for constructing a prestressed steel girder that is completed as a single long prestressed steel girder on site.

As a bridge construction method, a forward deflection load is applied to the steel girder in advance, concrete is placed on the lower seven lunges on the tension side so as to enclose the lower seven lunges, and after this concrete hardens, the forward deflection load is applied. A prestressed steel girder, commonly known as a pre-beam, is already known (Special Publication Publication No. 10/1973 λda), in which prestress stress is introduced into the lower 7 lunge concrete by the restoring force of the steel girder. .

A girder in which such a prestressed steel girder is erected on-site and then concrete and slab concrete are placed to completely cover the steel girder with concrete is called a pre-beam composite girder. This pre-beam composite girder has lower 7-lunge concrete and deck slab concrete combined with the steel girder, so the bend has greater stiffness, and the girder height can be lower than that of a normal composite girder. This is extremely advantageous for construction and construction of bridges that are subject to restrictions. Additionally, since the steel girder itself is not exposed, it has the advantage of not requiring maintenance such as painting, not generating noise, and being fire resistant.

The prestressed steel girder used to construct the pre-beam composite girder with these advantages is made by applying a bending load to a steel girder of a predetermined length in advance, and then concrete is poured into the lower seven lunges on the tensile side. After the concrete has hardened, the steel girder is bent by releasing the load and applying prestress to the concrete. At that time, prestressed steel girders with long spans are transported to the construction site in pieces due to transportation constraints, and after being connected at the site, a pre-bending load is applied. It has traditionally been customary to fabricate prestressed steel girders. Therefore, a fabrication yard is required at the bridge construction site, and there have been cases where a fabrication yard cannot be secured due to the bridge construction site in an urban area or the local topography. In addition, since the prestressed steel girders were manufactured on-site, there were problems in that the on-site construction period was long and the construction costs were relatively high.

The present invention solves the above-mentioned problems in constructing bridges using pre-beam composite girders, and makes it possible to construct long prestressed steel girders on-site. The purpose is to fabricate and erect a long prestressed steel girder block by transporting the disassembled prestressed steel girder blocks to the site and then connecting the blocks to form a single long prestressed steel girder.

In order to erect a prestressed steel girder intended for such a long pre-beam composite girder, the present invention applies a bending load to the lower seven lunges on the tensile side while connecting multiple steel girders in a factory or the like. Pour concrete leaving the joints open,
After the concrete hardens, the load is released to apply prestress to the concrete, and then the joints of the steel girders are disassembled and each steel girder block is transported to the site, where each steel girder block is reassembled. After connecting the joints, concrete is poured into the lower 7 lunges of the joint, and by connecting the two plates of the joint with PC steel rods, etc., and applying prestress to the concrete at the joint, the lower 7 flanges are placed over the entire length of the steel girder. This method is characterized by completing the erection of a long prestressed steel girder in which prestress stress is introduced into the lunge concrete.

Next, the erection method according to the present invention will be described in detail with reference to illustrated embodiments. Figs. 1a to 1e are side views showing the manufacturing process of prestressed steel girders in a factory, etc., and Figs. 2f to 2j are side views showing the construction site. FIG. 3 is a side view showing the construction process from the construction of steel girders to the completion of bridge construction using pre-beam composite girders.

As shown in Figure 1 aK, a plurality of steel girder members (1), (/l, (/
1° are integrally connected to the joint portion G2) via the original plate attachment plate (3) and the upper and lower seven lunge attachment plates (31). These steel girder members (1), (1) 2 (/13 are connected to each other
It is formed so that a predetermined camber is given in the state where it is held, and on the side of each joint, there are duplicate plates (6) between the upper and lower 7 lunges (IIl (j)) as shown in Fig. 3.
A stiffening plate (7) perpendicular to is fixed by welding.

Next, for the steel girder (1) connected in this way,
) K As shown, forward deflection load (preflexion) P
f and with a pre-deflection load Pf applied, concrete <1) is poured leaving the lower 7 lunges (j) and K joints (c) on the tensile side as shown in Figure 1C. This concrete (1) is formed so as to cover the lower seven flanges, excluding the joint (2), as shown in FIGS. 3 and 1.

After the concrete (1) of the lower 7 langes (jl) has hardened, the forward deflection load Pf applied to the entire length of the steel girder (1) is released as shown in Figure 1aK, and the restoring force of the steel girder (c) causes the concrete to harden. (, r) K is given a prestress stress respectively. In the closed state, the steel girder (1
) to each joint G2) to the joint plate (J), (31)
Separate by removing the steel girder blocks (9
Transport 1, (9) 2(?) 3 to the construction site.

As shown in Fig. f, the steel girder blocks (?), (IF) 2 (913) transported to the erection site have both ends set as temporary supports (
10) With the joint part (C) supported by K, the joint part (C) is again fully tightened and connected as one body through the splicing plate (31 (3/). Remove the lower 7 langes (Jl) at the joint (2) and add concrete, preferably expanded concrete (
11). After pouring this concrete (II), the stiffening plates (71) on both sides of the cylinder (plan and the joint part as shown in Figure 5) After the joint concrete (IJ-) (II') reaches a predetermined strength, prestress stress is introduced into the concrete (r/) by pulling the PC steel 41 (//''), and Lower 7 lunge (JL concrete) Gr
) (II> is in a state where prestress is applied.

Afterwards, as shown in Figure 1 IK, the upper 7 lunges (II) K are covered with concrete slab Q2 over the entire length of the steel girder (1).
), cover concrete for duplication (6)) (/J) will be poured. In Figure λj, the concrete floor slab) (/
J) The dead load (/#) and live load of K asphalt etc. are loaded, and the bridge construction is finally completed using the pre-beam composite girder.

As described above, in the prestressed steel girder construction method of the present invention, a plurality of steel girder members are connected together and a pre-bending load is applied as one steel girder, and in this state, the joint ( In order to apply prestress to the concrete by pouring concrete leaving 2) and releasing the pre-bending load after the concrete hardens, each steel girder member is placed at the lower flange on the tension side even if the joint is separated. It can be made into a precast steel girder block that is prestressed, making it possible to erect long prestressed steel girders at the site without being affected by the construction site conditions or transportation circumstances. .

In addition, the construction work at the construction site only requires continuous work for each steel girder block, short concrete pouring work for the lower seven lunges of the connection joint, and prestressing work for the first joint, and concrete work for the main part of the steel girder. Since there is no need to perform pouring, the cost of fabrication required at the erection site can be significantly reduced, making it more economical than the conventional pre-beam construction method, and the construction time at one site is shorter than the conventional method. Compared to the pre-beam construction method, it can be shortened to a large extent, and therefore has the effect of making the advantages of this type of bridge construction technology using steel girders even more effective.

[Brief explanation of the drawing]

Figures 1 a to e are side views illustrating the manufacturing process of prestressed steel girders in factories, etc. Figures 2 f to j are side views illustrating the erection process at the construction site, and Figure 3 shows details of the joint part. The perspective view shown in Figure D is N-WI in Figure 1e.
FIG. 5 is an enlarged side view showing the connected state of the joint shown in FIG. It is a sectional view taken along the line ■-■. In the figure, (c... steel girder N tl), (71g (1)3...
Steel girder member, -)...Joint part, (3) (3/)...
Attachment plate, (II)...upper 7 lunge, (j)...lower 7
Lunge, (4>... duplication, (7)... stiffening plate, (f
) <tt)...Concrete, (q), (ri)2(
d), ... Steel girder block, (lO) ... Temporary support, (
ll)...PC steel bar, (/J)...floor slab concrete Q
-), <13> ... belly plate covering concrete), (l
l)...Dead load after. 21 Patent applicant Kawada Kogyo Co., Ltd.'++'++
'+ N-1
-22-

Claims (1)

[Claims] L A forward deflection load is applied to a plurality of steel girders that are connected together via splicing plates in a factory, etc., and concrete is poured into the 7 tension side flanges of the connected steel girders, leaving joints in each. Applying prestress to the concrete by releasing the front deflection load after pouring and hardening the concrete,
The successor joints are separated and each prestressed steel girder block is transported to the construction site. At the site, each block is reconnected in the temporary construction state and concrete is poured into the lower seven rungs of the joint. A method for constructing a prefabricated prestressed steel girder, characterized in that the two sides of the slab are connected by a PC steel rod or the like to apply prestress to the joint concrete.