JPH055342A - Structure for arrangement of beam main reinforcement - Google Patents

Abstract

PURPOSE:To make high strength bars in yield strength of SD50 or more available for use as main reinforcements for beams by preventing rupture and bond splitting fracture in an area whereto stress concentration occurs, and to decrease therewith quantity of the bars required for beam main reinforcements while making bar arrangement work easy. CONSTITUTION:In a structure for arrangement of beam main reinforcements 10 to be executed for constructing reinforced concrete beams 12 that form, together with a column 11, a rigid frame, high strength bars in yield strength of SD5O or more are used as the beam main reinforcements 10. Bonding of concrete to the beam main reinforcements 10 is severed at least in a part of a hinge zone 16 adjoining a column/beam connection 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing structure for a main beam of a beam, and more particularly to a reinforcing structure for a main beam of a beam arranged in a reinforced concrete beam member that forms a rigid frame structure integrally with a column member.

[0002]

2. Description of the Related Art A high-rise building or the like adopts a rigid frame structure in which a column member and a beam member are integrally joined to form a continuous frame structure. And in such a ramen structure,
As shown in FIG. 3, in order to join the column member 20 and the beam member 21, the beam main bar 22 is protruded from the beam member 21 and is bent and fixed in the column-beam joint 23 with a predetermined fixing length. . On the other hand, when an earthquake load H or the like acts on the rigid frame structure 24, as shown in FIG.
It is known that an antisymmetric moment load is applied to 3 and, as a result, stress concentration occurs in a region that extends from the end surface of the beam member 21 by a length equal to the beam width D, that is, the hinge zone 25.

[0003]

However, in such a rigid frame structure, when the building becomes high-rise, the amount of reinforcing bars in the column members and beam members increases, and in particular, the reinforcing bars are complicated at the beam-column joints, which makes the reinforcing work difficult. Become. On the other hand, for the purpose of reducing the amount of rebar, in place of the standard SD30 to SD40 (yield strength of about 30 kg / mm ^{2 to} 40 kg / mm ² ) rebar, for example, SD50 (yield strength of 50 kg / mm ² ) or more, preferably Is SD
70 ~ SD80 (Yield strength approx. 70 kg / mm ² ~ 80 kg / mm ² )
It is conceivable to use considerably high strength reinforcing bars, but when using such high strength reinforcing bars, the following problems occur.

1) Since the tensile force that each reinforcing bar bears becomes large, vertical cracking of concrete around the reinforcing bars is promoted, and so-called adhesive splitting fracture easily occurs.

2) When a crack progresses due to stress concentration in the hinge zone 25 shown in FIG. 4 (b), as shown in FIG. 5, the reinforcing bar is exposed at the crack portion and the elongation due to the moment load is absorbed at the exposed length t. However, in the above high-strength reinforcing bar, the elongation as a property of steel decreases because the carbon content increases for the purpose of increasing the strength, and therefore the amount of elongation to be absorbed at the exposed length t is large. If so, it is easy to break.

Therefore, the present invention has been made to solve the above problems, and particularly when a high-strength reinforcing bar is used as a beam main bar, it is possible to prevent the reinforcing bar from breaking and adhesive splitting due to stress concentration, and also to prevent the reinforcing bar from breaking. An object of the present invention is to provide a reinforcing structure of a beam main bar which can reduce the amount and facilitate the reinforcing work.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned object, and its gist is to arrange bar main bars arranged in a reinforced concrete beam member forming a rigid frame structure with a column member. In the structure, a high-strength reinforcing bar of SD50 or more having a yield strength of about 50 kg / mm ² is used as the main beam of the beam, and at least a part of the hinge zone adjacent to the beam-column joint is made up of the main beam of the beam and the concrete. It is in the rebar structure of the main beam of the beam, which is characterized by cutting the bond between them.

Here, the high-strength reinforcing bar having a yield strength of SD50 or more means an SD which is usually used as a building reinforcing bar.
It means a linear steel material including a PC steel rod or the like having a strength exceeding 30 to SD40, that is, a yield strength of SD50 or more, and preferably SD70 to SD80 (yield, which is highly likely to be standardized as a high-strength reinforcing bar. Strength 70kg / mm ² ~ 80
Use of reinforcing steel equivalent to kg / mm ² ) facilitates the acquisition and design calculation.

Further, in order to cut the adhesion between the main beam reinforcement and the concrete, when the reinforced concrete beam member is manufactured as a precast concrete member or as a cast-in-place concrete member, the reinforcing bar located in a part of the hinge zone is For example, concrete is poured after covering with a sheath tube or a tubular body made of a foam material.

[0010]

In the reinforcing structure of the beam main bar of the present invention, the beam main bar sandwiches the non-adhesive part where the adhesion with the concrete is cut, and both sides thereof are fixed to the column-beam joint or the concrete of the beam member, and its function It supports the pulling force that must be borne without compromising. Further, by cutting the adhesion in a part of the hinge zone where the stress is concentrated, it is possible to prevent the occurrence of adhesive split fracture and absorb the elongation due to the moment load over the entire length of the area where the adhesion is cut.

[0011]

An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

In the reinforcing structure of the beam main bar of this embodiment, SD8 is used.
Use a reinforcing bar equivalent to 0 (yield strength of about 80 kg / mm ² ). As a result, the same load can be supported with half the amount of the reinforcing bar as compared with the case of using the reinforcing bar of SD40 (yield strength of about 40 kg / mm ² ). The beam main bar 10 is shown in FIG.
As shown in FIG. 3, at the beam-column joint portion 13 where the column member 11 and the beam member 12 intersect, the beam member is joined to the column member 11 by the adhesive force of the beam main bar 10 itself and the bearing force of the washer 15 attached to the beam main bar 10 by the nut 14. At the same time, in the hinge zone 16 of the beam member 12, that is, in an area that is approximately equal to the beam width D from the contact surface 18 between the column member 11 and the beam member 12,
The adhesion between the beam main bar 10 and the surrounding concrete is cut off by a sheath tube 17 whose both ends are covered with duct tape or the like. Further, when the beam member 12 is manufactured as a precast concrete member or as a cast-in-place concrete member, the sheath tube 17 can be easily embedded and installed by being attached before the concrete is poured. The buried length of the sheath tube 17 is a design matter as long as it can cut the adhesion between the main beam reinforcement 10 and concrete in at least a part of the hinge zone 16. Further, in the present embodiment, the beam main bar 10 has a straight end protruding and a fixing force by the washer 15 by the bearing force of the washer 15 in order to save the labor of working and further eliminate the complicatedness of the reinforcing bar at the beam-column joint 13. However, for example, as in FIG. 3, the end may be bent to secure a predetermined fixing length, and the column member 11 may be joined only by its adhesive force.

In the beam reinforcement structure having such a structure, the adhesion between the beam reinforcement 10 and the surrounding concrete is cut off at a part of the hinge zone 16 where the stress is concentrated, whereby vertical cracks in the concrete are prevented. It is possible to prevent the adhesive splitting fracture caused by the generation. Further, even after the crack progresses due to a repeated load such as an earthquake load, the elongation of the beam main bar 10 due to the moment load is, as shown in FIG.
Since it is absorbed by, the breakage of the beam main bar 10 is prevented without causing local elongation. Therefore, SD80
It eliminates the drawbacks caused by using the high-strength reinforcing bar, and makes it possible to use it as the beam main bar.

[0014]

Industrial Applicability As described above, in the reinforcing bar structure of the present invention, the adhesion between the main beam and concrete is cut at least in a part of the hinge zone adjacent to the beam-column joint. Even if a high-strength reinforcing bar is used as the beam main bar, it is possible to prevent the reinforcing bar from breaking and adhesive splitting fracture due to stress concentration. It is possible to facilitate the work of arranging the column-beam joints.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a reinforcing bar structure of a beam main bar of the present invention.

FIG. 2 is an explanatory view showing a situation in which elongation generated in the beam main bar is absorbed in the reinforcing bar structure of the beam main bar of the present invention.

FIG. 3 is a cross-sectional view showing a conventional reinforcing structure of a beam main bar.

FIG. 4 is an explanatory diagram of stress concentration due to an antisymmetric moment load applied to a beam-column joint when an earthquake load occurs in a rigid frame structure including a column member and a beam member.

FIG. 5 is an explanatory diagram showing a situation in which the extension generated in the beam main bar is absorbed at the exposed portion due to cracking.

[Explanation of symbols]

 10 Beam Main Bar 11 Column Member 12 Beam Member 13 Column-Beam Joint 16 Hinge Zone 17 Sheath Pipe

Claims (1)

Claim: What is claimed is: 1. A reinforcing structure for a beam main bar arranged in a reinforced concrete beam member forming a rigid frame structure together with a column member, wherein the beam main bar has a yield strength of SD50 or more. A reinforcing structure for beam main bars, characterized by using strong reinforcing bars and cutting the bond between the beam main bars and concrete in at least a part of the hinge zone adjacent to the beam-column joint.