JPH0369747A - Pc slab - Google Patents

Abstract

PURPOSE:To greatly increase economization by horizontally installing a precast flat beam with steels for bond prestressing integrally embedded therein, and by making a floor board with steels for unbond prestressing inserted thereto supported together with the flat beam. CONSTITUTION:Prestressed concrete precast flat beams 11 with steels 12 for bond prestressing embedded therein are installed in grille shape between columns 10. Tie hoops 13 are installed, protruding above the upper faces of the flat beams 11 and main reinforcements 14 are inserted into upper part of the tie hoops, and a floor board 15 is made up into one unit by means of casting concrete in site. After hardening of the concrete, stress is applied to an unbond cable 16 and prestressing is given thereby to the floor board 15 in the lengthwise and the breadthwise directions. Prestressing steels 18 for secondary stress are inserted into sheaths of the floor boards 15 and partial prestressing is given thereto. Thereby construction can be executed economically with number of reinforcements for girders lessened.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to prestressed concrete (hereinafter referred to as P
(denoted as C) relating to slabs.

(Prior art) Conventionally, a PC slab is also called a flat slab, and as shown in Figs. 8 and 9, the large eastern part 1, the small beam part 2, and the floor slab part 3 are integrated by pouring concrete on site. The PCI materials 4, 4...
... is buried and prestressed under tension to form a thin, strong slab.

This conventional PC slab has a thin overall structure, and is also PC@
Because it is necessary to generate a lifting force in the central part of the slab due to the tension of materials 4, 4, etc., a so-called unbonded cable is used, in which PC strands are inserted into a synthetic resin sheath and the gaps are filled with grease. There is.

In addition, in general, when building horizontally with a prestressed concrete structure using unbonded type PC steel materials such as unbonded cables, P
Since the tension caused by C steel may be released, P is applied to the main structural parts, at least the main beams.
It was necessary to create a design that had sufficient strength even when there was no tension due to the C steel material.

(Problems to be Solved by the Invention) Therefore, in the flat slab described above, a large amount of reinforcing bars were arranged in the portions corresponding to the large beams between the columns without including the PC steel materials in the stress calculation. This results in a high strength structure that is not required under normal conditions, resulting in a problem of high cost.

The present invention addresses the above-mentioned conventional problems and aims to provide a PC slab that can be constructed economically and has sufficient strength even in the event of a disaster with fewer reinforcements.

(Means for Constructing the Problem) The characteristics of the PC slab of the present invention that solves the conventional problems as described above and achieves the intended purpose are that the PC slab of the present invention is a bond type PC.
A precast flat beam with prestressed steel materials embedded in it is horizontally suspended, and a floor slab made of cast-in-place concrete is supported on the upper surface of the precast flat beam, and an unbonded type PC is installed on the floor slab. The reason is that prestress is applied to the entire area using the steel material.

(Function) The PC slab of the present invention uses a precast flat beam and has a bond type PC steel material embedded in it to create a prestressed concrete structure, so it is designed so that the PC steel material can withstand disasters. It can sometimes be used for stress calculations. In addition, the cast-in-place concrete floor slab integrated with the precast flat beam is
The entire structure is prestressed by unbonded PC steel, resulting in a thin yet highly elastic structure.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

1 to 5 show a first embodiment of the concrete flat slab of the present invention. This flat slab consists of columns 10, 10, made of cast-in-place concrete or precast concrete, and precast flat beams 11, 11 made of prestressed concrete between them.
. . . are constructed in a grid pattern, and the position of this flat beam 11 serves as a girder.

Each of these flat beams 11 is formed into a flat cross-sectional shape with a width larger than its height, and bond type PC steel materials 12 and 12 are buried inside in the longitudinal direction in addition to reinforcing bars, and a pre-tensioning method is used. Prestress in the longitudinal direction is applied by. Further, on the upper surface of this flat beam 11, hoop reinforcements 13, 13, . has been done.

A floor slab 15 made of cast-in-place concrete is integrally formed on the upper surface of the flat beams 11, 11, . . . , which are thus constructed between the columns 10, 10, .

The formation of this floor slab 15 can be carried out using the flat beam 1 as needed.
1, install shoring under the slab, assemble a template supported by the shoring on the bottom surface of the deck, place the necessary reinforcement on top of it, and unbond cable 16, which is an unbonded type PC steel material.
．． 16... are arranged vertically and horizontally except for the longitudinal direction on the flat beam 11, and cast-in-place concrete is poured. Thereafter, after waiting for the concrete to harden, the unbonded cables 16, 16, .

As shown in FIG.
The center part between 1 and 2 is placed low.

In addition, a bond type PC steel sheath is buried on each column 10, spanning the ends of the flat beams 11.11 adjacent in the longitudinal direction, with both ends opened on the upper surface of the floor slab 15. After the cast-in-place concrete of the floor slab 15 hardens, a bond type secondary tension PC steel material 1 is inserted into the sheath.
8 is inserted and tensioned to apply partial prestress to unify the girder section including the flat beam 11 in the longitudinal direction, and to reduce the upward stress on the column 10, the precast flat Stress concentration at the end position of the beam 11 is alleviated.

In the above-mentioned embodiment, the floor slab 15 made of cast-in-place concrete is formed on the upper surface of the flat beam 11, or the top 11a of the flat beam 11 is formed as in the second embodiment shown in FIG. is shaped like a mountain, and its top 11
a may be embedded in the floor slab 15 made of cast-in-place concrete, and further, as in the third embodiment shown in FIG.
5, and the bottom surface can be completely flat.

In addition, in the second and third embodiments, the same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

(Effects of the Invention) As mentioned above, the PC slab of the present invention uses a precast flat beam whose main beam part is prestressed with bond type PCA material, so that the PC steel material embedded in this flat beam can be Since prestress is not removed even in the event of a disaster, it can be included in stress calculations during design, and compared to the previous case where all prestress was applied using unbonded type PC steel, there were fewer reinforcing bars in the Daitobu area. Furthermore, when constructing the formwork for the floor slabs, the complicated construction of the eastern part was no longer necessary, making it significantly more economical.

[Brief explanation of drawings]

1 to 5 show a first embodiment of the present invention, FIG. 1 is a plan view of the entire slab showing the arrangement of each structural member, and FIG. 2 is taken along line A-A to FIG. 1. 3 is a sectional view taken along the line B-B, FIG. 4 is a sectional view of the girder, FIG. 5 is a sectional view of the top of the column, and FIG. 6 is a sectional view of the large eastern portion of the second embodiment. , Fig. 7 is a sectional view of the girder part of the third embodiment, and Fig. 8 is a 'ft43f!' of the conventional flat slab! A plan view showing the arrangement of members, and FIG. 9 is a sectional view taken along c-cMl in FIG. 8. lO... Column, 11... Precast flat beam, 12... PC steel material, 13...
...Hoop muscle, 14...Main muscle, 15...
・・Floor slab, 16・・・・Unboded cable, 18・・・・Secondary tension PC @ material. Figure 1 Figure 8 Figure 9

Claims (1)

[Claims] A precast flat beam that is prestressed by burying bond type PC steel materials is installed horizontally, and a floor slab made of cast-in-place concrete is supported on the upper surface of the precast flat beam. A PC slab made by applying prestress to the entire area using unbonded type PC steel.