JPS6085149A - Prestressed reinforced concrete 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] Industrial field of application This invention relates to a prestressed reinforced concrete girder in which tensile stress is introduced into the large diameter high-tensile reinforcing bars arranged on the tension side in a girder of a reinforced concrete structure, thereby introducing prestress into the concrete. It is.

Problems to be Solved by the Invention Generally, the condition of the reinforcement on the tension side of the girder of a reinforced concrete structure (referred to as RCi structure) is as shown in Fig. 1.
Three to six D30 reinforcing bars with a diameter of 19 to 25 VTBR are used. Therefore, as shown in Figure 2, by arranging one or a small number of large-diameter high-tensile reinforcing bars, the width of the conventional girder was determined based on the requirements of the reinforcement arrangement, resulting in a considerably larger width. However, the present invention aims to shorten the surgical time by using the above-mentioned muscle arrangement, and by extension, to reduce the weight of the girder. 4゜makuR
If high-tensile reinforcing bars are used in the C structure, the high strength of the reinforcing bars cannot be fully utilized because of the balance with the tensile strength of the concrete.

On the other hand, in a commonly practiced prestressed concrete structure, in order to introduce prestress, a prestressing steel material, such as a steel wire or a steel rod, is separately arranged in addition to ordinary reinforcing bars.

The purpose of this invention is to arrange high-tensile reinforcing bars in the reinforcing bars of an RC structure and introduce prestress using part of the strength of the reinforcing bars.

Structure of the invention and its embodiments The structure of the present invention is the same as described in the claims column, and uses a small number of large-diameter high-tensile reinforcing bars for the tension side reinforcing bars of the girder of a reinforced concrete structure. It is characterized by applying prestress to the girder using the surplus strength of the reinforcing bars.

The details will be explained below based on examples.

The reinforcing bar 1 used is, for example, a large-diameter high-tensile reinforcing bar such as a 5D50 threaded reinforcing bar. A tension reinforcing bar 3 is connected to the end of the above reinforcing bar 1 using a coupler 2, and the tension reinforcing bar 3 is inserted through the tensile force fixing device 4 and a nut 5 is tightened.
This causes tensile stress to be introduced into the reinforcing bar 1.

Furthermore, a suitable form (not shown) is assembled, concrete 1.6 is poured, and after the concrete 6 hardens, the nuts 5 are loosened to introduce prestress into the concrete 6 and the tension reinforcing bars 3 are removed.

By the way, the allowable tensile strength of 5D50 reinforcing steel is 3.
Although it is thought to be about OOOkylcr&, the tensile strength of the reinforcing bars designed as a reinforced concrete structure from the balance with concrete is 2.000 K! / / c++1, and there is a surplus strength of approximately 1.000 kg/GTrt.

Therefore, the tensile strength of the reinforcing bar is 1.000 Ky/c1
By applying tensile force r+ to the reinforcing steel and releasing the tensile force, compressive prestress is introduced into the concrete.

In the actual design, the tensile force to be introduced into the reinforcing bars 1 is determined by considering the creep of the concrete and the relaxation of the reinforcing bars.

When a load is applied to the girder with the above configuration, it initially acts as a prestressed concrete member, and the concrete
From the point at which the prestress in 1. becomes zero, it acts as a reinforced concrete member.

Effects of the Invention The present invention has the above configuration, and by using a small number of large-diameter high-tensile reinforcing bars, the web width can be made smaller than the web width of a conventional girder. Moreover, by using the surplus force generated by using high-tensile reinforcing bars to introduce prestress into the concrete, the high strength of the reinforcing bars can be utilized without waste.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional girder, FIG. M2 is a sectional view of the girder of the present invention, and FIG. 3 is a t-sectional view showing an outline of the manufacturing process of the girder. ■...Reinforcing bar, 2...Coupler, 3...Tensile reinforcing bar, 4...Fixing device, 5...Narit, 6
··concrete.

Claims (1)

[Claims] The reinforced concrete girder has a reinforced concrete structure in which the reinforcing bars arranged on the tension side are a small number of large-diameter high-tensile reinforcing bars, and a part of the strength of the reinforcing bars is used as prestressing of the concrete. prestressed reinforced concrete girder.