KR100960091B1 - Method for constructing a system structure by using of the pre-stressed steel girder - Google Patents

Abstract

The present invention relates to a method for manufacturing a steel girder in which prestress is introduced, a steel girder produced by the method, and a method for constructing a structure by applying a steel girder according to the present invention to a structure. In the process of manufacturing the girder, the prestress by temperature was introduced to offset part of the cross-sectional stress caused by dead and live loads.

In the case of constructing the steel girders according to the present invention to a bridge or steel structure, the amount of girder by removing the steel sheet 30 after joining to the pier 50 or the vertical column 60 without removing the steel sheet 30. The step is obtained by the restraint force of the piers 50 or the vertical column, and by the cross-sectional stiffness of the slab concrete or slab, to maximize the performance of the prestressed steel girders.

Prestressing, temperature prestressing, joining of the second girder and the lower section steel, structure

Description

Method for constructing a system structure by using of the pre-stressed steel girder}

The present invention relates to a method for manufacturing a steel girder in which prestress is introduced, a steel girder produced by the method, and a method for constructing a structure by applying a steel girder according to the present invention to a structure. In the process of manufacturing the girder, the prestress by temperature was introduced to offset part of the cross-sectional stress caused by dead and live loads.

According to the present invention, the webs are welded to each other by welding the girder 1b (hereinafter referred to as 'first girder') and the T-shaped girder 1a (hereinafter referred to as 'second girder') to each other. In the method of manufacturing an I-shape or H-shape steel girders, in a state in which compressive stress is introduced into the lower plate of the first girder by temperature prestressing before the webs of the two girders are integrated with each other. We propose an I-type or H-type steel girders fabricated by welding the webs of girders together to form a weld.

Furthermore, a technique for constructing a steel structure to be constructed by maximizing the performance of such prestressed steel girders is disclosed.

Pre-stressed steel girders have been used to improve the cross-sectional stress of steel girders.

The prestressed steel girders typically load the I- or H-beams 1 and impart a moment covering the design moment MD to deflect the I- or H-beams 1 and (Preflection) In this state, it was generally manufactured by the method of pouring, curing, and hardening concrete to a lower flange, removing a load, and introducing a compressive force to the lower flange concrete.

After that, the conventional method of pre-fractionation girder of the pre-stretching girder is removed from the construction method, at the construction stage to give a temporary temperature gradient to a part of the steel girder for a limited time, and after joining the site joint, the applied temperature gradient is removed The method of improving the bending moment by applying the temperature prestressing method to the steel girders by canceling part of the dead and dead forces acting on the steel girders by using the cross-sectional force generated when the steel girders are applied to the steel girders It has been suggested by the inventor.

Technical information on the construction of steel structures or steel girders by applying pre-stressing to girders by applying artificial temperatures to girders or plates can be found in Korean Publication No. 10-2002-0026775 (manufactured using temperature prestressing). Steel frame structure and its construction method) and Publication No. 10-2002-0024754 (Construction method of continuous steel girders using temperature prestressing),

The technical details of incorporating temperature prestressing into bridge reinforcement are well described in Publication No. 10-2002-0041719 (reinforcement of bridges using temperature prestressing).

Also, Publication No. 10-2003-0055061 (Continuous Method for PSC Beam Bridge Using Multi-stage Temperature Prestressing Method) and Publication No. 10-2002-0071272 (Reinforcement Method of Bridge Using Temperature Prestressing Reinforcement Bonding Method), Publication No. The technique which applied temperature prestressing is also shown in detail to 10-2006-0098239 (the construction method of some tableting cable-stayed bridge by the temperature prestressing method).

In the present invention, in the production of prestressed steel girders, by introducing pre-stressing in the manufacturing process of the steel girders, instead of introducing the pre-stress to the I- or H-shaped steel girders, to produce a steel girders, The purpose of the present invention is to provide an improved steel girders, and to provide a method for producing prestressed steel girders at low cost and easily. It is for the purpose of suggestion.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. In addition, the objects and advantages of the invention may be realized by the means and combinations indicated in the claims.

In order to achieve the above object, the production method of the prestressed steel girders presented in the present invention,

A first step of simply supporting and mounting both ends of the first girder having an X-shaped cross section; A second step of integrally fastening the steel sheet drawn by heating to the lower flange of the first girder; A third step of introducing prestressing such that a negative moment acts on the first girder by cooling the steel sheet; A fourth step of fabricating a steel girder by integrating a second girder having a T-shaped cross section against the web of the first girder is integrated.

In addition, in mounting the steel girders prepared by the fourth step to the structure, the horizontal beam of the cross-linking girder or the building structure after removing the steel sheet (step 5) before construction Although it may be used as a beam or the like, in the present invention, after the steel girder manufactured by the fourth step is installed (constructed) as a beam of a main girder or a ramen type structure of a bridge, etc. By presenting a construction method for removing the steel sheet in the prestressed steel girders according to the present invention can be effectively utilized.

The biggest feature of the prestressing method of the steel girder according to the present invention is not to prestress the steel girder at the construction site, but to give the steel girder pre-stressing at the factory for manufacturing the steel girder Since it is a method of manufacturing, not only can the prestressing work efficiency be increased as compared to performing the prestressing in the field, the workability in the construction site is reduced, so the workability can be greatly improved.

In addition, the structure construction method using the prestressed steel girders proposed in the present invention, because the main members of the structure to have the function of restraining the prestress introduced into the steel girders, girder due to dead and live loads of the structure Or there is an advantage to maximize the prestress effect of the beam.

Furthermore, unlike the method of prestressing the steel girders by using a tension material such as wire or tendon, prestressing is possible without any attachment to the outside of the steel girders, and thus, prestressing is possible once again by using the tension material at the construction stage. .

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A to 1C are conceptual views illustrating a general process of manufacturing an I-type or H-type girder, and FIG. 2 is a view illustrating a process of introducing prestressing to a girder according to the present invention, and FIG. 2 is a view showing the type of second girder that can be applied to the invention.

In general, H-type or I-type girders are manufactured and distributed to specified standards. The height (h1) of the ready-made standard products may be slightly different depending on the thickness and width (w). In the case of 600mm and H-shaped steel, the maximum length is only 900mm, so it is often unsuitable for long span steel girders of long bridges or steel structures. This is because the height (h2) of the long span or long span steel girders should be about 900-1,200 mm.

As shown in FIG. 1, the long girders or long span steel girders are formed by cutting the middle of the web of the I-shaped steel or the H-shaped steel 1 to form the first-shaped girders 1b and the T-shaped steel. After dividing into two girders (a), the auxiliary steel material 3 having the same thickness as the web is disposed between the first girder 1b and the second girder 1a to be integrally welded and manufactured (see FIG. 1A). ). As another method, as shown in FIG. 1B, after cutting the middle of the web of the I-shaped steel or the H-shaped steel 1 and dividing it into the first girder 1b and the second girder 1a, separately manufactured. The T-shaped second girder 2 may be placed on the web of the first girder 1b to be integrated by welding (see FIG. 1B), and in some cases, a flange and a web may be formed by welding ordinary steel. do.

By this method, the long girders or long span steel girders can secure a sufficient height h2. The present invention does not prestress the finished steel girders, but produces steel girders. There is a big feature in that it has a process of imparting prestressing.

As shown in FIG. 2, the method for manufacturing a pre-stressed steel girder according to the present invention includes a web 10a having both ends of the first girder 10 having a T-shaped or ⊥-shaped cross section as a first step. ) Is placed upward and the flange 10b is positioned at the bottom and mounted. This process is the same as the process of manufacturing a steel girder in general, as described above in Figure 1a or 1b. The first step is shown in Figure 2a.

As a next step, an elongated steel sheet 30 having a width equal to or similar to the width of the lower flange 10b of the first girder 10 is prepared, and heated and elongated to a predetermined temperature. At this time, the heating temperature and the heating section is determined in consideration of the amount of elongation of the steel sheet, but since the specific concept of the temperature prestressing is already known from the above-mentioned patent document, the description of the temperature prestressing technology itself is omitted in the present invention. Shall be. The second step is a process of integrally fastening the steel sheet 30 drawn by temperature to the lower flange of the first girder using the fastening bolt 31. 2B is drawn to explain the second step.

The third step is to cool the steel plate fastened to the lower surface of the flange of the first girder, and the steel plate 30 is gradually contracted while being cooled, while the upper portion of the first girder (ie, the web) is Since the shrinkage force does not work because it is at room temperature, the pre-stress of negative moment M ₁ is eventually introduced into the first girder by the compressive force applied to the lower flange of the first girder integrally fastened with the steel sheet. At this time, due to the compression force acting on the lower flange of the first girder, the tensile stress is generated on the upper portion of the net plane of the first girder, that is, the web 10a. 2C illustrates the third step.

As a fourth step, for the first girder in which the pre-stress of the negative moment M ₁ is introduced, the second girder 20 having a T-shaped cross section, as shown in the rightmost figure of FIG. The upper part of the web 10a of the girder 10 is integrated by welding. If necessary, as shown in FIG. 1A, the auxiliary steel material 3 may be disposed between the web 10a of the first girder 10 and the second girder 20 having a T shape to be integrally welded together. It should be understood that such changes should be included within the scope of the present invention. FIG. 2D is a drawing drawn to explain the fourth step, and FIGS. 4A, 4B, 4C, and 4D are exemplary views illustrating various forms of the second girder.

The fourth step is the most important step in the present invention. In the fourth step, when the tensile stress is applied to the web 10a of the first girder (that is, the web 10a of the first girder is tensioned), the second girder 20 is brought into contact with the upper surface of the web. The biggest feature is welding.

As a result of the fourth step operation, the upper end of the web 10a of the first girder is constrained by the second girder 20 while maintaining the tensioned state. Therefore, although the steel sheet 30 is still applying a compressive stress to the lower flange of the first girder, even if the steel sheet 30 is removed from the lower flange of the first girder, the web (1) 10a) Since the upper end is restrained by the second girder 20, the prestress applied to the first girder by the steel plate 30 is not completely extinguished (part of the applied prestress may be extinguished), Maintained by the second girder 20.

In the steel girder of the present invention, since the second girder 20 is welded to the upper end of the web 10a of the first girder, the web 10a of the first girder in tension is restrained from being returned to its original state. Since the second girder 20 welded to the upper end of the web 10a of the first girder is subjected to a compressive stress. That is, the prestressing effect of the steel girder according to the present invention is determined by the compressive rigidity of the second girder 20.

Therefore, in order to increase the compressive rigidity of the second girder 20, the cross section of the second girder 20 may be enlarged, or as shown in FIG. 4C or 4D, a large concrete slab or concrete slab resistant to compression may be used. It is particularly advantageous to be synthesized and molded integrally with The shear connector 21 is preferably provided for firm coupling between the flange 20b of the second girder 20 and the concrete top plate 40.

As shown in Figure 4, by integrally molding the concrete upper plate 40 resistant to the compressive force to the upper flange of the second girder 20, it is possible to maintain the prestress of the first girder to the maximum.

The second girder combined with the concrete upper plate 40 may be manufactured by pouring the concrete upper plate 40 during the process of preparing the second girder 20. Alternatively, the fourth step is completed, and the step of pouring the concrete deck 40 before the fifth step may be added. The concrete upper plate 40 prevents (constrains) the second girder 20 from being compressed, so that the stress applied to the first girder 10 is not restored and is maintained.

In the steel girder according to the present invention, since the prestress is maintained only by the girder itself, there is no external restraining element (for example, tandon or compressed concrete, etc.) for the prestress to be retained in the girder. That is, there are no attachments to the steel girders.

Therefore, for the pre-stressed steel girders according to the present invention, it is very easy to impart additional prestresses using wires or tandons. This is because there is enough space for the bracket to install tandon, which introduces additional prestress.

FIG. 3 shows that additional prestressing can be applied to the steel girder by a method of integrally fastening the steel sheet 30a elongated by heating to the lower flange of the steel girder manufactured by the present invention and then cooling it to room temperature. It is a figure explaining that there exists. An additional temperature prestressing method includes: a sixth step of integrally fastening a steel sheet 30a drawn by heating to a lower girder flange in which the fifth step is completed; And a seventh step of introducing prestressing so that the additional negative (M) moment M ₂ acts on the steel girder by cooling the steel sheet.

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A new type of prestressed steel girder can be obtained by the stages described above, or by removing the steel plate 30 which has been fastened in the second stage.

In applying the prestressed steel girder proposed in the present invention to the structure, rather than applying to the structure after removing the steel plate 30 which was fastened in the second step, it is mounted on the structure without removing the steel plate to the main structure of the structure It is particularly effective to remove the steel sheet 30 after joining with the main members.

5A, 5B, and 5C conceptually show an example of constructing a prestressed steel girder according to the present invention as a bridge girder, and fastening both ends (by bolt or welding) to a bridge bridge 50 of a bridge ( The fifth step), and the construction of the bridge is completed by pouring the upper concrete 40 (or placing the perforated plate). When the steel sheet 30 is removed after the bridge construction is completed, as shown in Figure 5a, the moment (Mr) that is to be restored to the steel girder, because both ends of the girder are coupled to the piers 50, The girder is not extinguished due to the binding force of the piers 50 and remains as it is. Here, the moment Mr is generated by the prestress not restrained by the second girder 20 but restrained by the steel plate 30 among the prestresses introduced into the first girder.

FIG. 5B illustrates an example in which crosslinking is performed using the prestressed steel girder 100 according to the present invention, and FIG. 5C conceptually illustrates a state in which the prestressed steel girder 100 according to the present invention is applied in constructing a continuous bridge. It is shown as.

6A and 6B conceptually show an example of constructing the prestressed steel girder 100 as a beam of steel structure according to the present invention, and fastening both ends of the beam to the vertical column 60 of the steel structure. And, placing the slab is shown a state in which the construction of the structure is completed. When the steel sheet 30 is removed after the construction of the structure is completed as described above, as shown in FIG. 6, the moment Mr, which is to be restored to the beam of the structure, of the structure coupled to both ends of the beam. It is constrained by the vertical column 60. Here, the moment Mr is generated by the prestress not restrained by the second girder 20 but restrained by the steel plate 30 among the prestresses introduced into the first girder.

In conclusion, when constructing a bridge or steel structure using prestressed steel girders, when the steel sheet 30 is removed after the steel sheet 30 is bonded to the pier 50 or the vertical column 60 without removing the steel sheet 30, Since both ends of the girder are coupled to the pier 50 or the vertical column, the restraint force and the cross-sectional stiffness of the slab concrete or slab provide the effect of maintaining the prestress applied to the steel girder as much as possible.

Steel girders produced by the present invention has the following advantages in that prestress is not maintained by external components such as tandon or compressed concrete, but is maintained only by the girder itself.

First, the construction is simplified because the accessory members such as steel wire, tendon, etc. are not attached to the outer circumferential surface of the girder.

Second, large prestress may be required depending on the design conditions or the characteristics of the structure. It is easy to introduce additional prestress by tendon or temperature prestressing for steel girders in which prestressing is introduced. In the case of conventional girder where prestress is maintained by external components such as tanden or compressed concrete, in order to add more prestress, additional tendons should be added, because there is a limitation of space to add tendons. Adding prestress was practically difficult.

The steel girders produced according to the present invention are not subjected to temperature prestressing to the steel girders in the construction stage, but to prestressing during construction of the steel girders at the factory. Compared to the prestressing work effect can be increased, as well as the field work is reduced, the workability can be greatly improved.

In particular, when constructing a steel girders according to the present invention in a bridge or steel structure, by removing the steel sheet 30 after the steel sheet 30 is bonded to the pier 50 or vertical column 60 without removing the steel girders, Both ends of the bridge are obtained by the binding force of the pier 50 or the vertical column, and by the cross-sectional stiffness of the slab concrete or slab, the performance of the prestressed steel girders can be maximized.

The steel girders produced by the present invention can be very usefully utilized as long gilts or long span girders.

1A to 1C are conceptual views illustrating a general process of manufacturing an I-type or H-type girder

2 is a conceptual diagram illustrating a process of introducing prestressing to a girder according to the present invention.

3 is a view for explaining a process of applying temperature prestressing to a steel girder manufactured by the present invention in a secondary manner;

4 is an explanatory diagram showing the type of second girder that can be applied to the present invention;

5 is a conceptual diagram illustrating an example of constructing a prestressed steel girder 100 as a bridge girder according to the present invention.

6 is a conceptual diagram illustrating an example of constructing a prestressed steel girder 100 as a beam of a steel structure according to the present invention.

<Description of Symbols for Main Parts of Drawings>

10: first girder 20: second girder

30: steel sheet 40: concrete slab or concrete slab

100: prestressed steel girder according to the present invention

Claims (2)

delete A first step of simply supporting both ends of the first girder (10) having a cross-sectional shape; A second step of integrally fastening the steel sheet 30 drawn by heating to the lower flange of the first girder; A third step of introducing prestressing to cool the steel plate 30 so that a negative moment acts on the first girder; A fourth step of fabricating a steel girder by integrating a second girder 20 having a T-shaped cross section against the upper portion of the web of the first girder; In the structure construction method comprising a fifth step of fastening both ends of the steel girder produced by the fourth step to the vertical member of the structure by bolts or welding, After curing concrete slab or top plate integrally with the structure, The method of constructing a structure using a girder, further comprising the step of removing the steel plate 30 is fastened in the second step.

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