KR20070020836A - Top-down construction structure and method using prestressed concrete beams - Google Patents

Abstract

The present invention is characterized by consisting of a column connecting means 30 installed in the steel pillars to join the steel pillars 10, prestressed concrete beams 20, the steel pillars 10 and the prestressed concrete beams 20 It relates to a reverse casting structure and a construction method of the same.

The present invention makes it possible to utilize the prestressed concrete beam in the reverse casting method, and it is difficult to absorb the deviation according to the verticality allowed in the H-beam thumb pillar of the conventional concrete, but it was difficult to adopt the reverse casting method. This problem has been solved and concrete beams can be used for reverse casting.

In addition, the present invention can eliminate the instability of the quality that can occur when the concrete beam on-site, it is easy to work because it is light, and can shorten the air has the effect of reducing the overall construction cost.

Description

Top-down construction structure and method using prestressed concrete beams}

1 is an assembly view of the steel pillar and concrete beam connecting portion according to the present invention.

2 is a first process diagram of a reverse casting method according to the present invention.

3 is a second process diagram of the reverse casting method according to the present invention.

4 is a third process diagram of the reverse casting method according to the present invention.

5 is a view showing in sequence the first, second, third process in the reverse casting method according to the present invention.

Figure 6 is a view showing the anchorage of the suspension strand used in the present invention.

<Explanation of symbols for the main parts of the drawings>

10: steel pillar 20: concrete beam

21: reinforcing hardware 23: length groove

24: connecting rod

30: pillar connecting means 31, 31a: bracket

32: horizontal brace 33: vertical brace

41: Suspension 42: Fixture

43: connection stage

50: upper slab

The present invention relates to a method for constructing a reverse casting method using a prestressed concrete beam. More specifically, the reverse casting method is usually performed by a steel column and steel beams, steel pillars and cast-in-place concrete, but the present invention relates to a construction method by installing a concrete beam made in advance in a factory.

As the modern economy grows, the demand for buildings is increasing, and urban land prices are continuously rising. As a result, office buildings, which are constructed in expensive urban centers, tend to exhibit high-rise buildings in order to efficiently use the land.

On the other hand, when constructing a structure underground, the conventional method, first to excavate the underground soil or rock to the depth necessary for the formation of the underground structure, and to prevent the collapse of the excavation surface supporting earth wall (strut strut) or earth anchor ( After the excavation was completed by installing an earth anchor, etc., it has been constructed by sequentially constructing structures of basement and ground layers from the foundation. However, according to this conventional method, the construction and dismantling of temporary construction takes considerable cost and time, and if the construction is inadequate, a large accident may occur due to the collapse of the earth retaining wall. There has been a problem of lengthening.

Therefore, the retrofit method has been developed and applied to improve the conventional structure construction method by constructing underground structures from the ground down and simultaneously constructing the ground structures in parallel. Reverse casting method is also called top down method, reverse pouring method, or downward construction method. Instead of digging the ground first to the required depth of basement, pre-install steel columns and install slab and column molds based on the pre-installed steel columns. It is a method of constructing a basement structure from the ground floor to the bottom by placing the. According to the reverse casting method, the ground is not excavated at the same time as the required depth, thus reducing the risk of collapse accidents caused by underground excavation. It is effective.

In the reverse casting method, a concrete structure such as a slab or beam is placed on the ground while the ground is stopped, and a method of digging the ground, selecting the ground, laying a club, installing a formwork, and then placing concrete is commonly used. However, in accordance with these methods, in order to start the excavation work of the lower layer after placing concrete, it is necessary to wait until the structure develops its strength after sufficient curing period, which inevitably leads to work waiting time. In addition, in order to excavate the ground of the lower part of the structure, the formwork and the copper barge were dismantled and moved to the upper floor so as not to interfere with the work of gulting, and the gulting work was carried out, which was cumbersome and difficult in terms of air and cost.

In order to solve the above problems, a suspension member, such as strand wire or rock bolt, is fixed to the upper layer structure and suspended by supporting the modular slab formwork, and then the concrete frame is poured into the formwork. After the excavation work of the rear lower layer, the suspension type unsupported reverse casting method was developed by repeatedly lowering the hanging supported formwork and proceeding the lower layer process repeatedly, and applied for and registered by the present inventors. 10-0261775, etc. can be confirmed.

Unlike the ordinary reverse casting method, the suspension type reversal method is a method of performing a reverse casting process using a suspension formwork without using a prop, that is, a slab supporting copper bar, and when using this method, a temporary copper bar is used. By not doing so, the construction work is simplified and the cost is reduced, and when applying the normal reversal method, when the work of the floor is performed, no digging work can be performed under the floor. Even during the curing curing process, it is possible to promote the excavation work under the formwork has the advantage of shortening the construction period.

In the case of using the suspension method, since the H-shaped steel was used to form the formwork, the H-shaped steel was a relatively expensive material, and had a considerable unit weight, so that the weight of the entire formwork was increased. If you want to construct the formwork by using, you have to cut the H-beam to the required size and use it only for the formwork. This H-beam is used for other purposes after the use as formwork. Because of this limitation, there were disadvantages in terms of versatility and economy of materials.

If the suspended concrete formwork and the large formwork are not used, and suspended concrete beams are suspended, air can be reduced without installing clubs and formwork on the ground, and thus there are many useful points.

However, due to the poor adaptability to dimensional changes due to the nature of the material of the concrete, it is difficult to apply it unless a plan for installing concrete beams corresponding to the dimensional range allowed for the H-beams is provided.

In addition, the use of prestressed beams as concrete beams would be useful because they can produce beams that are relatively small in size and lightweight because of their high strength relative to the unit volume.

The present invention is to provide a method for construction using a ready-made concrete beam in a reverse casting method.

In addition, the present invention is to provide a suspension-type reverse casting method that is easy to install and excellent in economic efficiency by suspending the prestressed concrete beam.

The invention is illustrated by the examples shown in the accompanying drawings.

The present invention is composed of a steel pillar (10), prestressed concrete beam 20, the column connecting means 30 as a structure and method for constructing a reverse casting method.

Steel column 10 uses the H-shaped steel that is usually used as a thumb pillar in the reverse casting method. Perforations are installed in the column position. Due to the nature of the reverse casting method, the vertical accuracy of the thumb column is usually limited to 1/500 or less.

Prestressed concrete beam 20 is manufactured at the factory. Sheath is installed in the mold for beam production, and a strand is inserted into the sheath, and concrete is cured and then tensioned and preloaded. This usually depends on the method of manufacturing the prestressed concrete beam.

When fabricating a prestressed concrete beam, the load is given in advance, so it can endure the load as large as that load, so that the beam cross section can be made small and the weight of the member can be reduced. Furthermore, by placing a hollow in the middle of the beam, it can be manufactured as a lightweight beam with high structural performance.

Prestressed concrete beams are pre-fabricated at the factory, so strict quality control is available, enabling the use of highly reliable products.

At the end of the prestressed concrete beam is formed in the vertical direction, there is an open slot 23 on one side. This length is formed so that the bracket protruding to the pillar through the groove can be inserted. Without this groove, it is difficult to install the prestressed concrete beam in place.

This length groove is combined with a bracket that is installed in the column, which will be described later. The length groove provides a means for absorbing the deviation and joining without difficulty even if there is a deviation in the span due to the allowable verticality of the thumb pillar.

The reinforcing hardware 21 is installed on the end vertical surface of the prestressed concrete beam. The reinforcing hardware reinforces the ends of the prestressed concrete beams to distribute the stresses and prevent the ends from breaking. At the top of the reinforcement, the vertical reinforcement of the column is joined (in a variety of ways, such as bolts, welds, and mechanical joints) to share some of the load on the prestressed concrete beams. Reinforcing hardware can be embedded in prestressed concrete beams or embedded in concrete when pouring concrete.

Prestressed concrete beams can be pre-stressed for lighter weights, and hollows can be formed in the middle of the beams for lighter weights. By forming the hollow portion, the structural rigidity can be increased while reducing the weight.

On the side of the prestressed concrete beam, a hole 25 penetrating the length groove is formed. Through this hole, the connecting rod 24 is fitted.

The pillars are provided with brackets 31 and 31a. The bracket is for supporting the prestressed concrete beam 20 when joining the column.

The bracket is welded to the column or joined to the bolt, it can be made in various forms such as 1-shaped 31, T-shaped (31a).

Bracket materials 32 and 33 may be further installed on the top or side of the bracket. In order to couple the prestressed concrete beam 20 and the brackets 31 and 31a, a predetermined clearance is required, but it is better to eliminate the clearance after installation. The lateral force transmitted through the prestressed concrete beam 20 should be transmitted to the next prestressed concrete beam through the column so that there is no gap to resist the lateral force. Install a brace to close this gap.

The construction sequence will be described with reference to the drawings.

Figure 2: First Step

First install the steel pillars 10 with the thumb pile.

The bracket 31 is installed by the column connecting means 30 where the prestressed concrete beam 20 is to be joined.

The prestressed concrete beam 20 transported to the lower portion where the bracket 31 is installed is suspended by the suspension material 41 and raised to the position of the bracket 31.

Figure 3: Second Process

The prestressed concrete beam 20 is mounted to the bracket position and the upper part of the suspension is fixed to the upper layer slab 50 by the fixing unit 42.

The fixing unit 42 has an inner piece (a) engraved with a male thread as shown in FIG. 6, an outer piece (b) engraved with a female thread to correspond to the inner piece, and an iron hole (c) is installed at the lower end of the outer piece. The outer side is installed on the fixing plate (e) above the slab. On the other hand, a conical hole is formed in the upper end of the inner piece, and a conical wedge (e) is provided into the hole. Strands, which are used as suspensions, are held in place by conical wedges after being loaded. After the prestressed concrete beams 20 are installed, the strands must be unwound in order to use them again. In the past, the loads were applied to the strands, and the strands were difficult to turn because of the frictional force. Fixture used in the present invention is convenient to be able to release the strands by easily rotating by installing a steel ball acting as a bearing at the bottom.

When the prestressed concrete beam 20 is in place, the connecting rod 24 is inserted through the hole 25 to couple the prestressed concrete beam 20 to the pillar.

The upper end of the reinforcing hardware 21 is coupled to the lower end of the vertical reinforcing bars by welding to share a part of the load applied to the beam.

At the top or side of the bracket, the support members 32 and 33 are further installed to eliminate horizontal gaps between the prestressed concrete beams 20 and the columns so as to cope with the horizontal load.

Figure 4: Third Process

After the prestressed concrete beam 20 is fixed, the slab concrete is poured. Since the prestressed concrete beam 20 is fixed, it may be installed as a deck plate for formwork or a general plywood formwork.

After the concrete is cured, the outer side (b) of the fixing unit 42 fixing the suspended material at the upper end of the suspended material 41 is rotated to release the strand and use it again to return to the first process.

Figure 5 shows the above process in order.

Although the present invention has been described above by the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the spirit of the present invention, and such variations and modifications will be construed as belonging to the appended claims. .

According to the present invention, it is possible to utilize the prestressed concrete beam in a reverse casting method.

Conventional concrete beams have been difficult to absorb the deviation according to the verticality allowed for the H-beam thumb pillar, but it was difficult to adopt in the reverse casting method, the present invention solves this problem it is possible to use the concrete beam in the reverse casting method.

In addition, the present invention can eliminate the instability of the quality that can occur when the concrete beam on-site, it is easy to work because it is light, and can shorten the air has the effect of reducing the overall construction cost.

Claims (7)

Steel column (10); Prestressed concrete beams 20; And Pillar connection means (30) installed on the steel column to join the steel column (10) and the prestressed concrete beam (20); Reverse pour structure, characterized in that consisting of. In claim 1, the prestressed concrete beam (20) has a length groove (23) is formed at the end, and the reverse casting structure, characterized in that the side is formed with a hole into which the connecting rod (24). The reverse casting structure of claim 1, wherein the pillar connecting means is a bracket (31) installed on the steel pillar. 4. The reverse casting structure according to claim 3, further comprising a support material (32, 33) at the top or side of the bracket. Inner pieces (a) with male threads; An outer piece having a female screw engraved corresponding to the inner piece; A steel ball (c) installed at the lower end of the outer piece; And, Conical wedge is installed on the upper end of the inner piece; Suspension fixing fixtures characterized in that consisting of. Installing the steel column 10 with the thumb pile, and installing the column connecting means 30 in the column where the prestressed concrete beam 20 is to be joined; The prestressed concrete beam 20 transported to the lower part where the column connecting means is installed is suspended by the suspension material 41 and raised to the position of the connecting means, and then the suspension material is fixed to the upper layer slab 50 as the anchorage of claim 5. To; Coupling the prestressed concrete beam 20 to the column by inserting a connecting rod 24 through the hole 25 of the prestressed concrete beam 20; And, Combining the prestressed concrete beams 20 and then placing slab concrete; Reverse casting method using a prestressed beam, characterized in that consisting of. The method of claim 6, wherein a support material (32, 33) is further installed on the top or side of the bracket.

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