JP3178911B2 - Prestressed concrete bevel precast box culvert and formwork used in its manufacture - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a precast box culvert made of prestressed concrete (hereinafter referred to as PC).
The present invention relates to a PC box culvert by a post-tension method.

[0002]

2. Description of the Related Art A PC box culvert in which a prestress such as a PC steel material is applied to a top plate and a bottom plate having a large bending moment due to a load by a tension member such as a PC steel material can greatly reduce labor on site and speed construction. , Because it is a factory product, the quality of the structure can be achieved, it is lighter than the cast-in-place box culvert, and the construction is easy, etc.It has features such as sewers buried under the road, for waterways, Widely used for passages and the like.

[0003] In general, PC box culverts are mainly cuboids whose front and rear ends are formed at right angles to the side walls. Particularly, bent portions and curved portions in the laying route, and attachment portions to existing structures, etc. A so-called oblique PC box culvert is used as a slab.

In order to effectively apply prestress and obtain a box culvert having a high strength, it is necessary to introduce prestress into the entire top and bottom plates of the box culvert. ,
High strength is required because stresses due to loads are easily concentrated. For this reason, there is a demand for a steel material arrangement for introducing prestress to the entire oblique PC box culvert.

[0005]

On the other hand, a jack used for prestressing the PC steel by tensioning the PC steel is attached to the end of the PC steel and used by taking a reaction force on the outer surface of the side wall of the box culvert. Have been. For this reason, the PC steel is disposed so that the PC steel and the outer surface of the side wall of the box culvert are orthogonal to each other. However, when introducing prestress into a conventional bevel box culvert,
All the PC steel materials arranged on the top and bottom plates cannot be perpendicular to the outer surface of the side wall of the box culvert.

[0006] For this reason, in the conventional beveled product, the beveled portion where the PC steel material cannot be made orthogonal to the outer surface of the side wall of the box culvert due to the difficulty in construction thereof has a reinforced concrete structure which does not introduce prestress,
As shown in the plan view of FIG. 7A and the enlarged view of the main part of FIG. 7B, when a jack 21 is mounted on the PC steel material 20 and a predetermined prestress is introduced into the oblique box culvert 22, This is dealt with by driving a wedge 23 between 21 and the side wall outer peripheral surface 22a.

However, making a part of the beveled box culvert into a reinforced concrete structure leads to a decrease in the strength of the entire box culvert, and using a wedge depends on the complexity of construction and the arrangement of PC steel. There are various problems such as the necessity of wedges of various shapes.

The problem to be solved in the present invention is that an oblique precast concrete box culvert that can introduce prestress into the entire oblique product using a conventional jack without requiring a special jig such as a wedge. And a mold used for the production thereof.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a prestressed concrete oblique angle precast box culvert formed by inclining at least one of the end surfaces thereof. That the tendon is inclined with respect to the axis to be provided, and that a reaction surface for jack attachment orthogonal to the axis of the tendon is formed on the outer surface of the side wall at the end surface of the tendon. Features.

Here, the reaction surface perpendicular to the arrangement axis of the tendon is formed by notching the side wall surface of the box culvert, or a part of the side wall surface of the box culvert is projected from the strength surface. It is desirable to form.

The prestressed concrete oblique angle precast box culvert can be manufactured by using a mold in which a flat surface and an inclined surface for forming the reaction force surface are formed integrally with the flat surface.

[0012]

In the bevel box culvert according to the present invention,
By forming the jack-attaching reaction surface orthogonal to the arrangement axis of the tendon material, it becomes possible to take the reaction force of the jack on this reaction surface when prestress is introduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the embodiments shown in the drawings.

FIG. 1 is a perspective view of an oblique angle precast box culvert made of prestressed concrete according to one embodiment of the present invention, FIG. 2 is a view showing the installation state of PC steel for a top plate and a bottom plate, and FIG. It is a part enlarged view.

1 is a beveled precast box culvert made of prestressed concrete having a long side of L _{1 and a} short side of L _s and having a slope on one side. 4 with a diameter of 19mm as a tendon
PC steel materials P ₁ , P ₂ , P ₃ , and P ₄ are provided.

The uppermost PC steel P ₁ shown in FIG. 2 has an axis X− orthogonal to the outer surface S ₁ of the side wall 4 of the box culvert.
X, i.e., arranged in parallel to relative upper end surface direction of the box culvert 1, P ₂ is tilted α with respect to X-X axis, and further P _3, P ₄ is β respectively, by γ inclined disposed . By providing such a PC steel material, it becomes possible to introduce prestress into the entire top plate 2 and bottom plate 3 of the oblique box culvert 1.

The end portions of the PC steel materials P ₁ , P ₂ , P ₃ , and P ₄ are respectively box culverts 1 by a fixing tool 5.
And the PC steel P of the box culvert 1
_2, P _3, the end surface of the P _4, PC steel P _2, P _3, P
Reaction surfaces R ₁ , R ₂ , and R ₃ for jack attachment that are orthogonal to the arrangement axis ₄ are formed.

[0018] Thus, for example, as shown in FIGS. 2 and 3, the PC steel P _1, jack 1 for prestress introduced
0 when worn, and despite PC steel P ₂ is not parallel to the X-X axis, and a bottom surface 10a of the jack 10, Hanchikaramen R
₂ can be easily set in close contact. Also,
The same applies to other reaction surfaces R ₂ and R ₃ . This coincides with distribution設軸axis and PC steel P ₂ of the jack 10 actuates the jack 10 by a conventional procedure similar to, it is possible to introduce the prestress to the PC steel member P _2.

In the above-described embodiment, the oblique box culvert having an inclination on one side has been described. However, the present invention is not limited to this, and it is a matter of course that the present invention can be applied to an oblique box culvert having an inclination on both sides. Further, the reaction surfaces R ₁ , R ₂ , R ₃ are not notched as in the above embodiment,
It is also possible to those which projects from the side wall 4 the outer surface S _1.

FIG. 4 shows the box culvert 1 of the above embodiment.
(A) is a plan view and (b) is a front view.

The manufacturing formwork of this embodiment includes an inner formwork 20, an outer formwork 21, an oblique partitioning formwork 22 for forming an oblique angle,
In addition, an end form (not shown) for closing both ends is provided, and first and second auxiliary inner forms 23 and 24 for fixing PC steel materials P ₁ , P ₂ , P ₃ and P ₄ are provided. ing.

The first auxiliary inner mold frame 23 is formed by a single plate as shown in FIG. 5, and has a flat surface 23a and reaction surfaces R ₁ , R ₂ and R ₃ shown in FIGS. Are formed, respectively, to form the inclined surfaces 23b, 23c and 23d. The inclined surfaces 23b, 23c and 23d are respectively inclined by α, β and γ with respect to the flat surface 23a. Reference numeral 23e denotes a projection for forming a concave portion formed integrally with the auxiliary mold frame 23.

Further, the second auxiliary mold 24 is provided with a PC in the middle.
The projections 25 for fixing the steel materials P ₁ , P ₂ , P ₃ , and P ₄ are formed.

By using such a formwork,
Using the conventional box culvert formwork, the prestressed concrete oblique angle precast box culvert 1 shown in FIG. 1 can be easily manufactured. At this time, the inner forms 23, 24 correspond to the arrangement direction of the PC steel.
Only the inner mold 20 and the outer mold 21 which are used for the production of general box culverts need not be processed.

FIGS. 6A and 6B show a manufacturing state of a box culvert using a mold according to still another embodiment, wherein FIG. 6A is a plan view and FIG. 6B is a front view.

In this embodiment, the auxiliary mold is not provided, and the outer mold 30 is divided into three parts: an upper outer form 31, an intermediate outer form 32, and a lower outer form 33. The intermediate outer frame 32 has a flat structure as in the prior art, and the upper outer frame 31 and the lower outer frame 33 are formed with the reaction surfaces R ₁ , R ₁ , R 2 in the same manner as the auxiliary frame shown in FIG. ₂ , inclined surface 31 for forming R ₃
a, 31b and 31c are formed respectively.

In the present embodiment, components corresponding to the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted.

The box culvert 1 shown in FIG. 1 can be easily manufactured by using the mold of the present embodiment. In particular, since there is no need to attach the inner formwork inside the outer formwork as in the previous embodiment, rapid construction is possible.

[0029]

According to the present invention, the following effects can be obtained.

(1) It is possible to introduce prestress into the entire prestressed concrete oblique angle precast box culvert without requiring a jig such as a wedge as in the prior art.

(2) It is possible to provide a prestressed concrete oblique angle precast box culvert which is prestressed throughout and has excellent strength.

(3) Efficient production can be achieved by using a predetermined mold.

[Brief description of the drawings]

FIG. 1 is a perspective view of a prestressed concrete oblique angle precast box culvert according to an embodiment of the present invention.

FIG. 2 is a view showing a state of installation of PC steel materials on a top plate and a bottom plate.

FIG. 3 is an enlarged plan view of a main part of FIG. 2;

4A is a plan view showing a state of the box culvert shown in FIG. 1 during manufacture, and FIG. 4B is a front view.

FIG. 5 is a perspective view of an auxiliary mold shown in FIG. 4;

6 (a) is a plan view showing another embodiment of a mold used for manufacturing the box culvert shown in FIG. 1, and FIG. 6 (b) is a front view.

FIG. 7 (a) is a plan view showing a construction state of a conventional oblique box culvert, and FIG. 7 (b) is a front view.

[Explanation of symbols]

1 box culvert 2 top plate 3 bottom plate 4 side walls _{P 1, P 2, P 3} , P 4 PC steel S ₁ sidewall outer surface R _1, R _2, R ₃ Hanchikaramen 10 jack, 10a bottom 20 inside formwork jack 21 Outer formwork 22 Partitioning formwork 23 First auxiliary inner formwork 23a Flat portion 23b, 23c, 23d Inclined surface 23e Projection 24 Second auxiliary formwork 30 Outer formwork 31 Upper outer formwork 31a, 31b, 31c Inclined Surface 32 Middle outer mold 33 Lower outer mold

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E03F 3/04

Claims (2)

(57) [Claims] In a prestressed concrete oblique angle precast box culvert formed by inclining at least one of the end surfaces, a tension member is arranged obliquely with respect to an axis perpendicular to a side wall surface of the box culvert. An oblique angle precast box culvert made of prestressed concrete, wherein a reaction surface for jack attachment is formed on an outer surface of a side wall at an end surface portion of the tendon material, and the orthogonal direction to an arrangement axis of the tendon material. 2. The formwork for producing a prestressed concrete oblique angle precast box culvert according to claim 1, wherein a flat surface and the inclined surface for forming the reaction surface are formed integrally with the flat surface.