JPH0329938B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable not only to reinforcement structures such as reinforced concrete containers, floors, and slabs, but also to plate-shaped members such as slabs that receive concentrated loads with no particular limitation on the position of action. This invention relates to a reinforcement structure for reinforced concrete members suitable as a reinforcement structure for.

[Conventional technology]

In general, a plate-like member without shear reinforcement exhibits brittle punch-out shear failure properties when a concentrated load F ₀ is applied, as shown in FIG.

If the location where this concentrated load acts is determined, shear reinforcement using stirrups or bent reinforcing bars may be used, but this is only effective if the shear reinforcement is sufficiently anchored and the placement density is not large. It cannot be. Furthermore, in order for these shear reinforcements to be effective, continuous wire rods (axial reinforcing bars) must be placed above and below, and shear reinforcement bars must be placed to connect the upper and lower wire rods. .

However, since the thickness of the plate-like member is thin, it is difficult for the shear reinforcing bars to be sufficiently anchored, and even if the shear reinforcing bars are arranged, the effect cannot be expected to be much.

For this reason, other types of shear reinforcement methods using shaped steel and the like are being considered.

On the other hand, for concentrated loads that do not have a limited location of action, such as impactful external forces such as collisions and explosions, and moving concentrated loads such as the wheel loads of automobiles, reinforcement of the entire surface of the plate is required. Arranging bent reinforcing bars over the entire surface of the plate so that they work effectively is even more difficult than the above case, including the problem of fixation, and is considered impossible from a practical standpoint.

For this reason, in the case of road bridge slabs that are subject to moving concentrated loads, conventional methods have been developed to avoid consideration of punch-out shear by increasing the slab thickness and keeping the reinforcing bar ratio low, and by changing the placement of H-shaped steel etc. Therefore, two methods of strengthening slabs are being considered. However, when H-shaped steel is placed, there is a risk of adhesion failure between the concrete and the H-shaped steel.

Therefore, it can be said that there is currently no efficient method of arranging shear reinforcing bars for plate-like members that receive concentrated loads that are not particularly limited in their acting positions.

[Problem to be solved by the invention]

Therefore, the present invention has a structure that has excellent strength and toughness against concentrated loads as well as distributed loads, and also has a structure that restrains concrete deformation three-dimensionally. To provide a reinforcement structure for reinforced concrete members that has a large effect of restraining deformation, is suitable for introducing chemical prestress into expansive concrete, is relatively easy to construct, and is suitable not only for on-site reinforcement but also for factory production. The challenge is to

[Means to solve the problem]

The present invention has been made to solve the above problems, and consists of four corrugated wire rods each having diagonal lines H, I, J,
Diagonal reinforcement units U ₁ , U _{2 .} . . are assembled so that K intersects three-dimensionally in an are welded to the upper and lower vertical and horizontal wires arranged in a grid pattern in advance, or after inserting one of the vertical and horizontal wires into the hollow part of the diagonal reinforcement unit, the other wire is inserted inside or in contact with the outside, and welded or It is characterized by being connected by a binding line.

FIG. 2 is a diagram explaining the principle of the present invention, and FIG. 51 is arranged, and a concentrated load is applied to the top of the corrugated wire 52.

As shown in figure a, when a large concentrated load is applied to the center, diagonal cracks 53 occur due to shearing as shown by the dotted line, but if shear reinforcing bars are placed perpendicular to this, the reinforcing effect is You can expect it. However, as mentioned above, this is limited to the case where there are wire rods on the upper and lower sides, and the upper and lower wire rods and the corrugated wire rods are connected or fixed by welding or the like.

However, if failure is determined by bending,
The location where large cracks occur is the A-A cross section, and the bending resistance of this cross section becomes the bending strength of the beam element, so diagonal reinforcement works effectively as shear reinforcement when shear cracks occur. It is not effective against bending.

On the other hand, if the other corrugated wire 52' is arranged in a shifted manner and the diagonal reinforcements are made to intersect as shown in figures b and c, the C-C cross section is better than the B-B cross section.
The bending stiffness and bending strength are larger than those of the B-B and D-D cross sections, and in the case of bending failure, large cracks occur on the B-B and D-D cross sections, and small cracks occur on the E-E and F-F cross sections, but This has the same effect as when wires are placed at the intersection. This is because the horizontal component of the force acting on the diagonal muscle is effective for bending.

Furthermore, for shear, the load acting position is b
In the case of the figure, diagonal muscles G, H, and K work directly and effectively,
In addition, the diagonal striations I and J act to alleviate the occurrence of shear cracks.

Even when the load is applied at the position shown in figure c, a similar resistance mechanism is provided, and no matter where the load is applied, it can effectively resist shearing. In order to obtain this shear reinforcing effect in a plate-like member, it can be achieved by forming a set of four diagonal reinforcements and arranging them three-dimensionally so that the four diagonal reinforcements intersect three-dimensionally, as shown in FIG.

In other words, by intersecting four diagonal reinforcements, the diagonal reinforcements can function not only as shear reinforcing reinforcements but also as bending reinforcements, and in addition, a structure that can restrain the internal concrete three-dimensionally has been created. Therefore, a plate-like member with high toughness can be obtained.

Furthermore, as shown in the example of FIG. 4 described later,
By arranging the intersecting positions of the four sets of diagonal strips in a staggered arrangement, shear reinforcement and bending reinforcement can be efficiently performed on the plate-like member.

On the other hand, if the amount of wire rod used is normally used for beams or plate-like members, bending cracks will occur when the load is small.

In the case of reinforcement in which diagonal reinforcement intersects, bending cracks occur in the cross section at the intersection, and as the neutral axis moves, the effect of the diagonal reinforcement acting as a bending reinforcement increases, but along with this, In figure b, tensile force acts on diagonal muscles I and J, which have a shear crack mitigation function.

As a result, the diagonal muscles I and J also become restraining muscles and can function effectively against shearing.

Furthermore, if sufficient shear reinforcement is performed, the failure of the member will be in the form of bending, and the greater the cross-sectional bending resistance, the greater the member's yield strength will be. When used in conjunction with upper and lower lattice-shaped wire rods in a staggered arrangement, the reinforcement itself becomes a high-order statically fixed structure.
Even if cracks occur, the deformation of the internal concrete is restrained, making it possible to obtain a plate-like member with extremely high toughness.

Therefore, it can be said that making diagonal reinforcement function for both shearing and bending is an efficient reinforcement method.

The above configuration is particularly effective in the case of plate-shaped members that are internally statically indeterminate and in a three-dimensional stress state, and that are subjected to concentrated loads. In addition to the restraint effect as a shear reinforcement, it also has the function of a bending reinforcement, so it can resist large loads even in the region beyond the maximum load on the load-deflection curve, and has excellent toughness. I can do it.

For this purpose, it is necessary to arrange diagonal reinforcements that intersect three-dimensionally in a form that provides sufficient fixation and is effective in two or more directions.

The present invention attempts to apply this principle to plate-like members.

Conventionally, there have been examples in which the reinforcement method shown in Fig. 2a is applied to the reinforcement of plate-like members, but the reinforcement method shown in Fig. 2b and c has been applied to three-dimensional reinforcement of plate-like members. I can't see any examples of it being applied.

This is because even if the former method is implemented, the reinforcement work is troublesome, and furthermore, when the latter method is attempted to be implemented, it becomes extremely troublesome with known structures.

Therefore, as described above, the present invention uses four corrugated wire rods and constructs diagonal reinforcement units U ₁ , U ₂ .
... are arranged in parallel with the bent parts of the corrugated wire rods shifted by 1/4 pitch with respect to the adjacent diagonal reinforcement units, and then welded to the upper and lower vertical and horizontal wire rods arranged in a lattice shape in advance, or in the hollow part of the diagonal reinforcement unit. After inserting one of the vertical and horizontal wire rods into the wire, the other wire rod is inserted inside or abutted on the outside, and the structure is connected by welding or binding wire, which has succeeded in its industrialization.

Embodiments of the present invention will be described below based on the drawings.

〔Example〕

FIG. 4 shows an example of its implementation, in which figure a is a plan view, figure b is a front view, and figure c is a side view.

FIG. 5 is an explanatory diagram showing a method for constructing a three-dimensional truss diagonal muscle body X'', in which four corrugated wire rods 21 to 24 are interlocked in an X shape so that each diagonal wire H, I, J, and K intersect with each other. The diagonal reinforcement units U ₁ U ₂ . A straight member 3 in the direction is inserted, and a straight member 4 in the horizontal direction orthogonal to the straight member 3 is brought into contact with the lower or upper part of the straight member 3 in the vertical direction, and bound by a bind wire (not shown) or welding. A three-dimensional truss oblique muscle body X'' is constructed.

Note that it is not necessary to tie all the contact points; you can easily shape the structure by tying only the important points, for example, only the surrounding contacts, and if you tie the appropriate number of points, you can obtain the desired reinforcement structure. It will be done.

In this way, by forming a set of four corrugated wire rods, a diagonal reinforcement intersection where four diagonal reinforcements intersect three-dimensionally as shown in Fig. 3 is formed, and it has excellent toughness and rigidity, and also has excellent toughness and rigidity as described below. Reinforced concrete members with various characteristics can be obtained.

Figure 6 shows a different embodiment, in which vertical and horizontal straight members 3 and 4 arranged in a lattice pattern are used as diagonal reinforcement units.
U ₁ U ₂ ... has a structure that comes into contact with the top and bottom of...
The structure of the oblique muscle unit U ₁ U _{2 .} . . is the same as the embodiment shown in FIG.

In the embodiments shown in FIGS. 4 and 6 above, the intersection positions of the four diagonal reinforcements are arranged in a staggered manner in the short side direction, so the shear reinforcing reinforcements can be arranged evenly, and the diagonal reinforcement This has the effect of equalizing the magnitude of cross-sectional bending strength due to the presence of the unit. Furthermore, in addition to the fact that the slab itself is inherently statically unstable, incorporating this diagonal reinforcement unit significantly increases the statically constant order, making it easy to redistribute stress in response to cracking. becomes. In this case, since the reinforcing structure of the present invention three-dimensionally restrains the internal concrete, stress distribution is better than when ordinary shear reinforcing bars are used.

Furthermore, the anchoring effect as a shear reinforcing bar is extremely good not only because continuous wires are used, but also because the straight members 3 in the vertical direction are restrained three-dimensionally.

The vertical straight members 3 are indispensable for taking charge of bending rigidity and anchoring the shear reinforcement, but in the cross section at the intersection of the four diagonal reinforcements, the tension side and compression side The wire rod has the function of restraining the hinge formation at the intersection point.

This reinforcement structure has extremely excellent yield strength and toughness.

Furthermore, when it comes to impact loads, backside peeling due to stress waves, which is a primary response, is particularly likely to occur at the intersection of diagonal stripes, but by placing the horizontal straight members 4 at these positions, peeling can be prevented. The subsequent quasi-static secondary response can absorb as much energy as static concentrated loads, and the structure is retained even after failure. effective.

In addition, when configuring the three-dimensional truss oblique muscle body,
Assembly can be speeded up by fixing the intersection points with annealed iron wire or spot welding to the extent that they can stand on their own.

In addition, when the straight members 3 and 4 are placed outside the diagonal reinforcement units U ₁ , U ₂ . . . as in the embodiment shown in FIG. 6, the straight members 3 and 4 are spot welded in advance. The assembly can be speeded up by assembling them in a lattice shape, and then connecting the diagonal muscle units U ₁ , U ₂ . . . on top of it.

The reinforced concrete plate-like member constructed as described above with reinforcing bars buried therein has diagonal reinforcements that intersect with each other evenly, so it has high yield strength and toughness not only for distributed loads but also for concentrated loads. It has excellent properties and can resist the load equally no matter where it is applied.

Furthermore, when manufacturing in a factory due to its structure, pre-stressing can be easily introduced, so it is also possible to provide products with even better toughness and rigidity.

Furthermore, since the stiffness of the reinforcement itself is greater than that of normal reinforcement, there is a practical benefit of simplifying the shoring when concrete is poured on-site.

〔Effect of the invention〕

As detailed above, the reinforcing structure according to the present invention has excellent characteristics, so it can be used for precast road bridge decks, factory floors where local loads from heavy objects and machinery act, roof slabs and walls of important structures, etc. shear wall,
It is suitable as a flat slab, a replacement for steel structures whose usability such as flexure is ignored because there is no problem in terms of strength, such as reinforcement structures such as pedestrian bridges or reinforced concrete containers for dumping radioactive materials.
Its application range is extremely wide.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a state of push-out shear failure due to concentrated load, Fig. 2 is an explanatory diagram of the principle of the present invention, Fig. 3 is a perspective view showing the configuration of the grade-separated intersection in the present invention, and Fig. 4 is an illustration of the present invention. A plan view, a front view, and a side view of an embodiment of the invention, FIG. 5 is an explanatory diagram of a method of assembling a space truss diagonal muscle body, and FIG. 6 is a plan view and a front view of another different embodiment. X″...Three-dimensional truss diagonal bar body, 3 and 4...Straight material, 21-24...Corrugated wire material, H, I, J, K...
...oblique muscle, U ₁ , U ₂ ... oblique muscle body unit.

Claims (1)

[Claims] 1 A diagonal reinforcement unit made of four corrugated wire rods so that the diagonal reinforcements H, I, J, and K intersect in an X-shape.
U ₁ U ₂ ... for each adjacent oblique muscle unit,
The bent parts of the corrugated wires are arranged side by side with a 1/4 pitch offset.
After welding them to the upper and lower vertical and horizontal wire rods arranged in a grid shape in advance, or inserting either the vertical and horizontal wire rods into the hollow part of the diagonal reinforcement unit, the other wire rod is inserted inside or abutted on the outside, and welded. Or a reinforcement structure of reinforced concrete members that are connected by binding wires.