JPH0610434U - Precast concrete beams - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a precast concrete beam that can be stretched between columns without supporting work by increasing the proof stress of the precast concrete beam, and can exert resource saving and economic effects. . [Structure] A PC steel material 4 is inserted into both side walls 3 of a precast concrete beam 1 and the PC steel material 4 is tensioned to apply prestress.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a precast concrete beam with prestress introduced.

[0002]

[Prior art]

 In recent years, columns, beams, floor slabs, etc. are being precast to compensate for the extreme labor shortage and to improve workability. Among them, precast concrete beams having a U-shaped cross section as shown in Fig. 5 are widely used. In this precast concrete beam 10, the stirrups 20 protruding from the upper surface are embedded in the floor slab 30, and the post-cast concrete 40 for the floor slab 30 is cast in the U-shape so as to be integrated with the floor slab 30 and the pillar. It has been made into.

[0003]

[Problems to be solved by the device]

 However, this precast concrete beam has low yield strength, and it was difficult to reduce the amount of temporary material because the support work was placed when bridging between the columns. Also, in buildings with large floors and floor heights such as warehouses and offices, cracks and flexure control are affected by the size of the beam cross section, increasing the weight of the building and the floor height, resulting in resource saving and economy. It was difficult to achieve the desired effect.

The present invention has been made in view of the above problems, and an object thereof is to increase the proof stress of a precast concrete beam so that the precast concrete beam can be bridged between columns without providing a supporting work, and It is to provide precast concrete beams that can achieve resource saving and economic effects.

[0005]

[Means for Solving the Problems]

 The precast concrete beam of the present invention for achieving the above object is a precast concrete beam with a U-shaped cross section in which the upper part of the stirrups protrudes from the upper surface, and PC steel material is inserted into both side walls of the precast concrete beam. The pre-stressed steel beam is pretensioned by tension, and reinforcing ribs are provided between both side walls of the precast concrete beam.

[0006]

[Action]

 Since PC steel material is inserted into both side walls of the precast concrete beam having a U-shaped cross section and the PC steel material is tensioned to apply prestress, the proof stress of the precast concrete beam is increased. Supporting work can be omitted when precast concrete beams are bridged between columns, and resource saving and economic effects can be exhibited.

[0007]

【Example】

 An embodiment of the precast concrete beam of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view of a precast concrete beam of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a plan view thereof.

The precast concrete beam 1 has a U-shaped cross-section with ribs 2 protruding from the upper surface, PC steel material 4 is inserted into the bottom of both side walls 3, and the PC steel material 4 is tensioned and prestressed. . The PC steel material 4 is a stranded wire of PC steel, a reinforcing fiber material, or the like, and an arbitrary proof stress is applied to the precast concrete beam 1 by prestressing it with pretension or posttension.

Further, the PC steel material 4 is not only inserted into the bottom portion of the side wall 3, but as shown in FIG. Can also be given.

FIG. 3 shows a structure in which a reinforcing rib 5 is provided between both side walls 3 of the precast concrete beam 1. The reinforcing rib 5 prevents the precast concrete beam 1 from buckling due to an increase in prestress. Is.

Next, a method of constructing the precast concrete beam 1 will be described. A precast concrete beam 1 produced at a factory or on site is laid between columns 6 with a crane. In this case, since this precast concrete beam 1 has a sufficient proof stress, it is not necessary to install a temporary material such as support work.

Then, a precast concrete plate 7 is laid on the upper surface of the precast concrete beam 1 spanned between the columns 6, and a post-cast concrete 8 is cast on the precast concrete plate 7 to form a floor slab 9. At this time, the post-cast concrete 8 is cast into the U-shaped groove 1a of the precast concrete beam 1, and the stirrup 2 is embedded in the floor slab 9, whereby the precast concrete beam 1 and the floor slab 9 are integrally molded. .

[0013]

[Effect of device]

 In a precast concrete beam with a U-shaped cross section in which the upper part of the stirrup protrudes from the upper surface, PC steel is inserted into both side walls of the precast concrete beam, and prestress is applied by tensioning the PC steel. Since the proof stress of the precast concrete beam can be increased and the supporting work can be omitted, the temporary material can be reduced and the economic effect can be achieved.

By providing the reinforcing ribs between both side walls of the precast concrete beam, it is possible to prevent buckling of the precast concrete beam due to an increase in prestress.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a precast concrete beam constructed.

FIG. 2 is a front view of a precast concrete beam constructed.

FIG. 3 is a plan view of a precast concrete beam provided with reinforcing ribs.

FIG. 4 is a front view showing a state in which a precast concrete beam in which a PC steel material is inserted in a curved shape is constructed.

FIG. 5 is a cross-sectional view of a conventional precast concrete beam.

[Explanation of symbols]

 1 Precast concrete beam 2 Stirrup 3 Sidewall 4 PC steel 5 Reinforcing rib

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Claims (2)

[Scope of utility model registration request] 1. A precast concrete beam having a U-shaped cross section in which the upper part of the stirrup protrudes from the upper surface, PC steel is inserted into both side walls of the precast concrete beam, and the PC steel is tensioned to prestress it. A precast concrete beam that is characterized by 2. The precast concrete beam according to claim 1, wherein reinforcing ribs are provided between both side walls of the precast concrete beam.