KR20090039903A - Preflex composite beam and its manufacturing method - Google Patents

Abstract

A preplex composite beam and a method of manufacturing the same are disclosed. The manufacturing method of such a preflex composite beam includes the steps of forming a camber on the girder, mounting the opposite side on which the camber of the girder is formed on a cradle, and supporting the support plate with a support plate, and supporting the girder with the support plate. A step of applying a load to both ends in a support plate direction, placing and curing concrete on the opposite side of the camber of the loaded girder, and introducing a prestressed load to the girder by releasing the loaded load from the girder; It includes.

Description

Preflex composite beam and its manufacturing method {MULTIFUL BEAM AND MANUFACTURING METHOD OF THE SAME}

The present invention relates to a preflex composite beam and a manufacturing method, and more particularly, by installing a horizontal support plate on a camber-formed composite beam to load a load, to close the support plate as close as possible to minimize the deformation error of the girder by introducing a bending moment. The present invention relates to a preflex composite beam and a method of manufacturing the same, which can generate a compressive force close to a design value in tension-side concrete.

In general, preflex composite beam generates a bending moment by applying a load to the girder and then pours the concrete on the tension side, removes the load, generates the opposite bending moment, and introduces prestress into the tension-side concrete. It is a structure to effectively resist.

Such preflex composite beams not only have prestress introduced into the lower flange concrete, but because the entire mold is surrounded by concrete, the rigidity is larger and the deflection is smaller than that of other types of the same mold height.

In the process of manufacturing the conventional preflex composite beam, as shown in Figures 1 and 2, the upper and lower girders (1, 2) having a camber is mounted on the support (3) as a pair, the upper and lower girders Preflection loads are introduced into the upper and lower girders 1 and 2 by applying a load to a load device such as a hydraulic jack at both ends of (1, 2).

Then, after the concrete is poured on the tensile side of the upper and lower girders (1, 2), the loads loaded on the ends of the upper and lower girders (1, 2) are removed.

As such, when the loads loaded on the upper and lower girders 1 and 2 are removed, the compressive force acts on the concrete, so that the preflex composite beams into which the preflex load is introduced can be manufactured.

In the conventional preflex composite beam, as shown in FIG. 2, since the load is applied at two points P1 and P2, the bending moment becomes the maximum bending moment at the two loading points P1 and P2. .

However, such a conventional preflex composite beam is deformed in advance by the weight of the girders mounted on the support, so that the deformation and the theoretical value by a predetermined preflection load occur, so that the preflection load as designed value is not introduced into the girder. There is a problem that the required compressive force is not introduced to the tension-side concrete.

In addition, due to this error, the preflex composite beam has a portion exceeding the bending moment, which causes a problem in that an excessive compressive force is introduced in a part of the tension-side concrete, so that the required amount of material is larger than necessary.

That is, the preflex composite beam manufactured by the conventional manufacturing method loads at two points, so the bending moment becomes the maximum bending moment at the loading point, while the required compressive force is introduced to the tension-side concrete at the point where the maximum cross-sectional force occurs. There is a problem that can not efficiently produce a preflex composite beam because it is not.

Accordingly, an object of the present invention is derived to solve the above problems, an object of the present invention is to inevitably occur by the weight of the girder by manufacturing a composite girder by applying a flat support plate to the girder camber is formed It is to provide a preflex composite beam that can generate bending moment by minimizing error and introduce compressive force close to design value in tension side concrete.

Another object of the present invention is to apply a cross-sectional force corresponding to the required bending moment throughout the girder by applying a planar support plate can be used to effectively use the cross-section of the composite beam and to achieve structural safety and material savings An object of the present invention is to provide a preflex composite beam and a method of manufacturing the same.

In order to achieve the object as described above, a preferred embodiment of the present invention comprises the steps of forming a camber on the girder; A loading step of mounting the opposite side on which the camber of the girder is formed on a holder and supporting the support plate; A loading step of applying a load in the direction of the support plate to both ends of the girder while supporting the girder with the support plate; Placing and curing concrete on the opposite side of the camber of the loaded girder; And it provides a preflex composite beam manufacturing method comprising the step of introducing a pre-stress load to the girder by releasing the load loaded from the girder.

As described above, in the method of manufacturing the preflex composite beam according to the present invention, a flat support plate is installed in the longitudinal direction between the support points when the preflex load is applied to the preflex composite beam, and the load is loaded to make the upper and lower rigid shapes as close to the support plate as possible. Since the moment is introduced, there is an advantage of minimizing the deformation error of the girder which can occur during the preflection load introduction process by generating uniform deformation in the upper and lower dies and generating compressive force close to the design value in the tension-side concrete.

In addition, the bending moment is generated in the girder by using the displacement difference between the maximum amount of the lift and the supporting point, so that the bending moment that is close to the required bending moment during common use in the shear surface in the longitudinal direction can be efficiently introduced into the tension-side concrete. There is an advantage that can be manufactured more secure composite girder.

Hereinafter, with reference to the accompanying drawings will be described in detail a method of manufacturing a preplex composite beam according to a preferred embodiment of the present invention.

As shown in FIG. 3, the method for manufacturing a preflex composite beam proposed by the present invention includes a camber forming step S100 of the girder 10, a mounting step S110 of the girder 10, and a girder 10. The prestressing load is applied to the girder 10 by releasing the loaded load from the loading step (S120) of applying a load, the step of placing concrete and curing the loaded girder (10), and the load from the girder (10). Introducing step (S140).

In such a preflex composite beam, in the camber forming step S100 of the girder, an camber C is formed on one side of the girder 10 by applying an external force to the girder 10 having a predetermined cross-sectional shape. In this case, the girder 10 preferably includes a girder 10 having an I-shaped cross section.

In the mounting step S110 of the girder, two girders 13 and 15 having cambers C formed thereon are placed on the holder 21 in a pair of up and down. That is, the upper girder 13 is placed on the upper side of the holder 21, and the lower girder 15 is placed on the lower side of the holder 21.

At this time, the support point on the girder 10 supported by the holder 21 is preferably placed so as to be located at the L / 4 point of the girder length.

The upper and lower girders 13 and 15 are placed so that the opposite directions in which the cambers C are formed face each other.

And, the support plate 23 is disposed between the upper and lower girders (13, 15). At this time, the support plate 23 has a predetermined length in a horizontal shape. Accordingly, the support plate 23 supports the upper and lower girders 13 and 15 by being disposed between the upper and lower girders 13 and 15.

In this state, the loading step (S120) for introducing a load to the girder 10 is in progress. In this loading step (S120), as shown in FIG. 6, loads are respectively applied to both ends of the upper and lower girders 13 and 15 stacked on the holder 21. That is, the hydraulic jacks are mounted at both ends of the upper and lower girders 13 and 15, and the hydraulic jack is operated to load the load.

In this way, when loads are applied to both ends of the upper and lower girders 13 and 15, the intermediate portion of the upper and lower girders 13 and 15 supported by the supporting plate 23 is in close contact with the upper and lower surfaces of the supporting plate 23.

Accordingly, the preflection loads are loaded on the upper and lower girders 13 and 15, and the bending moments are introduced by the upper and lower girders 13 and 15 being brought into close contact with the upper and lower surfaces of the support plate 23 by the preflexion load. Can be.

As a result, since the load is introduced until the upper and lower girders 13 and 15 are in close contact with the support plate 23, the portion in close contact with the support plate 23 has a shape close to a straight line, and thus deformation close to the theoretical value occurs.

Then, as shown in the diagram shown in Fig. 8A, a bending moment close to the design value can be generated.

In addition, as shown in FIG. 7, when the upper and lower girders 13 and 15 are in close contact with the support plate 23, when the load is further loaded, the upper and lower girders 13 and 15 are at the edges of the support plate 23. By contacting the load, the load is applied at two points P3 and P4.

Therefore, the middle portions of the upper and lower girders 13 and 15 are opened in the vertical direction about the support plate 23 to cause deformation.

At this time, the bending moments generated in the upper and lower girders 13 and 15 form a diagram as shown in FIG.

In this state, both ends of the upper and lower girders 13 and 15 are fixed by the clamping member so that both ends of the upper and lower girders 10 maintain the loaded state.

Then, the concrete placing and curing step (S130) for the girder 10 is in progress. That is, concrete is poured into the flanges of the upper and lower girders 13 and 15 loaded with loads, respectively. Then, it is cured by steam or sprinkling for a certain time.

As such, after the curing step (S130) of the concrete, the prestress introduction step (S140) proceeds. In this step, after curing the concrete, the clamping members mounted at both ends are separated.

When the clamping members are separated from both ends of the upper and lower girders 13 and 15, a bending moment having a sign opposite to the loading load is generated by removing the preflection loads loaded on the upper and lower girders 13 and 15. That is, the bending moment as shown in Fig. 8 (c) occurs.

The bending moment will be described in more detail. According to the theoretical value, the maximum bending moment of a certain magnitude is generated between the support point and the support point when the preflection load is loaded by the conventional method.

Therefore, according to this conventional method, excessive bending moments are introduced in some sections in order to generate a required bending moment that resists the maximum bending moment occurring at the center point of the girder 10 in common.

However, in the case of the preflex composite beam according to the present invention, the bending moment of the shape as shown in Fig. 8 (b) occurs first when the support plate 23 of the flat shape is supported and the load is applied using the rising amount. As a result, the bending moment that must occur at the support point is reduced.

The bending moment generated by the above method is close to the shape of the bending moment actually generated during the use of the composite girder 10 and can efficiently generate the compressive force required for the tension-side concrete in the longitudinal direction.

After the prestress introduction step (S140) as described above, the preplex composite beam is constructed on site.

That is, the composite beam in which prestress is introduced is loaded on the vehicle with the torsional deformation minimized by using a mechanism such as a turnover wheel device.

The prestressed composite beam is transported to the site and placed on both supports. In this state, the prestressed composite beam is finished by placing bottom plate, haunch, abdomen, cross beam concrete, etc.

1 is a view schematically showing a manufacturing method of a girder according to the prior art.

Figure 2 is a graph showing the bending moment by the girder shown in Figure 1;

Figure 3 is a flow chart showing a method of manufacturing a girder according to a preferred embodiment of the present invention.

4 is a perspective view showing a girder according to the present invention.

FIG. 5 is a perspective view showing a state where the girder shown in FIG. 4 is placed on a holder; FIG.

FIG. 6 is a view schematically showing a state in which a load is applied to the girder shown in FIG. 4.

FIG. 7 is a view schematically showing a state in which prestress is introduced into the girder shown in FIG. 4.

Figure 8 (a) is a view showing the bending moment diagram acting on the girder shown in Figure 4, Figure 8 (b) is a view showing the bending moment and the amount of rise of the girder, Figure 8 (c) is introduced into the girder This is the bending moment diagram that occurs when the preplex load is released.

Claims (6)

Forming a camber on the girder; A loading step of mounting the opposite side on which the camber of the girder is formed on a holder and supporting the support plate; A loading step of applying a load in the direction of the support plate to both ends of the girder while supporting the girder with the support plate; Placing and curing concrete on the opposite side of the camber of the loaded girder; And And a step of introducing a prestressed load into the girder by releasing the loaded load from the girder. The method of claim 1, wherein the supporting plate has a horizontal shape in the loading step. The method of claim 1, wherein the girder is placed in upper and lower portions of the cradle by using a pair of upper girders and lower girders, respectively. The method of claim 3, wherein in the loading step, both ends of the upper and lower girders are fixed by a clamping member. The girders on which the cambers are formed are placed in a state supported by a support plate on a cradle, and a load is loaded on both ends of the girders in the direction of the support plate, and then concrete is placed and cured on the opposite side of the camber of the loaded girders, and from the girder A preflex composite beam that can be manufactured by introducing a prestressed load into the girder by releasing the loaded load. The preflex composite beam according to claim 5, wherein the support plate has a predetermined length in a horizontal direction.

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