KR100562758B1 - Manufacturing method of precast composite beam - Google Patents

Abstract

According to the present invention, a precast composite beam is fabricated by synthesizing a steel mold to a lower concrete precast member in a state in which a tension member is tensioned and fixed to a lower concrete precast member to introduce a predetermined compression prestress. After that, the present invention relates to a precast composite beam manufacturing method in which a second or second compression prestress is introduced to a lower concrete precast member again, and the synthetic beam manufacturing process is simple, thereby reducing the air shortening and construction cost required for the production. In addition, by introducing prestress over the first, second, or second order, the compressive stress considered in the design can be efficiently introduced into the lower concrete precast member, so that the tensile crack can be controlled efficiently. It can improve durability and stress due to creep and dry shrinkage (priest S) It can reduce the loss, and when the segment is manufactured and installed in the factory or the manufacturing site, the quality control of the synthetic beam and its transportation and installation are easy, so that the design and construction (transportation and installation) of the composite beam can be more efficient. The present invention relates to a method for producing a cast composite beam.

Composite beam, prestress, tension material, segment, preflex

Description

Manufacturing method of precast composite beam

Figures 1a and 1b shows a part of the manufacturing process of the conventional preplex composite beam,

Figure 1C shows a cross-sectional view of a conventional leafless preplex composite beam.

Figure 2a shows a steel mold constituting the precast composite beam integrally fabricated the entire span of the present invention,

Figure 2b shows a lower concrete precast member and the longitudinal cross-sectional view of the primary prestress introduced in the present invention,

Figure 2c shows a longitudinal cross-sectional view of a state in which a secondary cast or a second or more prestress is introduced into a precast composite beam and a precast composite beam in which the steel mold and the lower concrete precast member of the present invention are synthesized.

Figures 3a, 3b and 3c shows a specific example of the connection method of the steel mold and the lower concrete precast member of the present invention.

4 illustrates a conceptual diagram in which a tensile force is introduced into an upper flange of a steel mold when a secondary or secondary compression prestress is introduced into the precast composite beam of the present invention.

Figures 5a, 5b and 5c is a steel mold constituting the precast composite beam of the present invention produced by segmenting the entire interval, the lower concrete precast member and the primary steel and the lower mold precast The second or second prestress is introduced into the precast composite beam in which the precast member is connected.

Figures 6a and 6b show an embodiment of connecting the precast composite beam of the present invention with the bottom plate concrete.

<Description of Major Symbols in Drawing>

300: precast composite beam

310: lower concrete precast member

320: steel casting

330a, 330b: Tension material

330c: tension receptacle

340a, 340b, 340c: segmented steel mold

350a, 350b, 350c: segmented lower concrete precast member

400: bottom plate concrete

The present invention relates to a method for manufacturing a precast composite beam, and more particularly, in a state in which a tension member is tensioned and fixed to a lower concrete precast member and a predetermined compression prestress is introduced to the lower concrete precast member. The present invention relates to a precast composite beam fabrication method in which a precast composite beam is synthesized to be integrated with each other, and then a secondary or secondary compression prestress is introduced into the lower concrete precast member.

Looking at the manufacturing process of the composite steel beam (pre-plex beam, etc.) made by synthesizing the steel mold and concrete according to the prior patent No. 1163 (pre-stress composite beam manufacturing method), as shown in Figure 1a steel mold 100 Casing concrete 200 is formed by placing and curing concrete on the lower flange after applying a predetermined pre-flection load (P1) to the casing concrete, and removing the pre-flection load as shown in Figure 1b, the casing concrete by the elastic restoring force of the steel mold By introducing a kind of compression prestress into the body, it is possible to secure the rigidity and durability corresponding to the external load (prevention of tensile cracking of the casing concrete by the live load acting after the completion of the bridge). In other words, in order to prevent tensile cracking occurring in the casing concrete due to the external load, a model in which a pre-flection load is applied to the steel mold in advance is necessarily preceded.

In addition, looking at the manufacturing process of the leafless preflex steel composite beam manufacturing method similar to other conventional composite beams of Patent No. 244084, as shown in Figure 1c the steel mold (100, I-shaped steel) in advance to generate a predetermined bending moment Load the pre-fraction load, and cast the concrete on the lower flange to form the casing concrete 200, remove the pre-load load previously loaded to introduce the primary compression prestress to the casing concrete, and then to the casing concrete in advance Secondary compression prestress is introduced by the installed tension member 210, and as a result, it is effective to prevent the tensile cracking of the casing concrete, but also to prevent the tensile cracking occurring in the casing concrete caused by external load. It was essential to apply a reflection load.

The prefraction load loading type requires a special manufacturing facility according to the size and length of the steel mold, and also has a problem in that quality control of load positioning, load recovery, and load loading is not easy. It was well known that the construction cost was increased because it was necessary to construct a work site for the fabrication and secure a transport route when the composite beam was manufactured at the production site and then installed on the bridge undercarriage.

In the fabrication of composite beams for bridges using such a pre-loaded construction model, even though the problems caused by the pre-loading loading construction are as described above, the necessity to solve them has emerged. It was not happening.

Accordingly, the applicant of the present invention, while maintaining the effect of the same height as the composite beam manufactured by using the existing pre-flexion loading model without complicated work, such as pre-loading loading ball, bridges that can ensure the durability and safety of the required Developed composite beam for girder

It is an object of the present invention to manufacture a composite beam for a bridge utilizing only the merit of the mechanical behavior of concrete and steel molds. By using the tension member installed in the cast member in the longitudinal direction, the prestress is introduced and the required composite beam is manufactured without the prefraction load. It is possible to shorten, and to provide a precast composite beam manufacturing method that can reduce the construction cost for the composite beam production due to the cross-sectional reduction effect on the steel mold, the lower flange.

Another object of the present invention is to pre-stress introduced into the lower concrete precast member, in the factory easy to quality control, the pre-stress can be accurately introduced to the lower concrete precast member firstly at the stress level considered in the design, In addition, the prestress can prevent tension cracking of the lower concrete precast member of the composite beam, as well as the time-dependent stress (prestress) loss of concrete such as self-weight, live load, creep, and dry shrinkage acting on the composite beam. Is introduced into the lower concrete precast member in the second or second order, making it possible to manufacture and construct a more efficient composite beam. Precast composite beam for easy quality control of composite beams To provide a construction method.

According to the present invention, in order to fabricate the precast composite beam, a prefabricated steel mold is separately manufactured, and in the case of the lower concrete precast member, a tension member is installed in a longitudinal direction inside a concrete member having a predetermined cross section and a length, and then Tension and fixation at both ends of the concrete precast member allows the required prestress to be introduced first (precasting, in this case pre-tensioning means and re-stressing means for introducing the second or second prestress The steel mold and the lower concrete precast member are synthesized with each other, and then transported to the site, and the prestress required for the lower concrete precast member is additionally (secondary or second or higher). And precast composite beams over the entire span or segmented Efficient construction is possible.In particular, when manufacturing the lower concrete precast member over the entire area, the first prestress can be introduced by the pretension method, and the lower concrete precast member and the steel mold are connected in a non-synthetic state. In the state, the primary prestress is introduced to the lower concrete precast member, and the connection between the steel mold and the lower concrete precast member is connected (synthesized) by grouting or the like, and then the secondary or secondary prestress is connected to the lower concrete precast member. What can be produced by the introduction method is the technical characteristic.

Best Mode for Carrying Out the Invention The best embodiment of the present invention will now be described with reference to FIGS.

Precast composite beam 300 of the present invention comprises the steps of introducing a primary compression prestress using a tension material to the lower concrete precast member 310 in a non-synthetic state with the steel mold 320; Manufacturing a composite beam by connecting the lower concrete precast member and the steel mold 320; And further introducing at least a second or more compression prestress into the lower concrete precast member. It includes.

2A and 2B illustrate a steel mold 320 and a lower concrete precast member 310 required for fabricating the precast composite beam of the present invention, respectively.

The steel mold 320 is generally I-shaped steel, as shown in Figure 2a, but other material steel having a cross-sectional shape of the other required, such as the truss shape and the cross section having a corrugated abdominal steel may be used according to the purpose of use.

The steel mold 320 according to the present invention is characterized in that it is connected to the lower concrete precast member as it is, without being pre-loaded in advance in the manufacture of the composite beam. Furthermore, considering the case in which the lower concrete precast member is slightly bent upward by the primary compression prestress introduced into the lower concrete precast member 310, the steel mold can be easily connected to the lower concrete precast member. The lower concrete precast member is bent upward as much as it is bent upward.

The lower concrete precast member 310 is a member having a predetermined cross-sectional shape, and its length, strength, prestressing method (pretension or post-tension method) and tension member installation method (adhesive, non-adhesive) are the length of the steel, the use position. And functional purpose and design method.

In the case of Fig. 2B, the lower concrete precast member is made into a rectangular parallelepiped shape or the like (which may be manufactured as various shapes), and the length thereof is manufactured to correspond to the length of the steel mold, and the length thereof is in the longitudinal direction (L direction). Since a plurality of tension members 330a are installed and tensioned by the tensioning device and then fixed at both ends of the lower concrete precast member, the compression prestress is primarily introduced into the lower concrete precast member. 2B shows a state in which the primary prestress is introduced into the lower concrete precast member 310 in a longitudinal sectional view, wherein the primary prestress is gradually introduced according to the length of the lower concrete precast member. It can be shown, it may be introduced in duplicate in a certain length.

Reference numeral 330c of the lower concrete precast member indicates a tension member receiving means (such as a sheath tube) so that the tension member can be installed later. This shows that the required compressive prestress can be introduced into the second or second order at different times by separating the prestress of the required first through the installation of additional tension material (330b), tension, and settling work.

The lower concrete precast member 310 is manufactured in a factory and has an advantage of very easy quality control. Especially, in the case of the first prestress, the lower concrete precast member 310 is introduced according to a design by a pretension or posttension method in a factory or near a site. There is an advantage that the production efficiency can be improved.

FIG. 2C illustrates a state in which the steel mold 320 and the lower concrete precast member 310 are connected to each other (synthesized), and the steel mold 320 is disposed on the lower concrete precast member 310 in various ways as possible. 3A, 3B, and 3C are attached to each other, but are to be integrated with each other.

3B illustrates a lower concrete precast member 310 having a plurality of holes 311 formed in an upper surface thereof, and FIG. 3A illustrates a shear connector 321 protruding from a lower surface of an I-beam lower flange to correspond to the hole. Figure 3c shows the formed steel mold 320, Figure 3c introduces the primary prestress in a state in which the lower concrete precast member 310 and the steel mold 320 in a non-synthetic state, grouting with a filler such as mortar After synthesis, the lower concrete precast member 310 and the steel mold 320 is shown an example in which the secondary or secondary prestress is introduced in a state connected to each other.

Thus, the precast composite beam 300 in which the steel mold 320 and the lower concrete precast member 310 are combined with each other is manufactured as shown in FIG. 3C. Unlike the conventional composite type fabrication method in which the composite beam is directly preflected with a steel mold in a state previously integrated with the lower concrete precast member, the prestress is introduced into the lower concrete precast member. Since the primary compression prestress is adopted as it is connected to the lower concrete precast member in which it is introduced, the compression prestress is not introduced into the steel mold, and after the steel mold and the lower concrete precast member are synthesized, Even when the composite beam for the bridge girder is manufactured by introducing additional prestress, it is possible to introduce compression prestress that can prevent tensile cracking due to the load generated on the lower concrete precast member without complicated work such as pre-flection loading work.

Furthermore, by installing tension members 330a and 300b in the lower concrete precast member 310, the prestress is introduced directly through the primary and secondary (possibly even secondary), so that the required amount of prestress is required as necessary. It can be accurately measured and introduced, and there is a structural advantage that can sufficiently compensate for the time-dependent stress (introduced prestress) loss of concrete, such as creep, dry shrinkage, which occurs largely in a conventional preflex composite beam.

After manufacturing the precast composite beam 300 introduced preliminarily by the tension member 330a into the lower concrete precast member 310 at the factory and transporting it to the site, the lower concrete precast member 310 as shown in FIG. When the tension member 330b is inserted into the tension member accommodating means 330c formed in advance in the entire region, and is tensioned and fixed at both ends, prestress is introduced into the lower concrete precast member 310 secondly. do. FIG. 2C is a longitudinal cross-sectional view of the composite beam in which the secondary prestress is introduced into the lower concrete precast member while the lower concrete precast member and the steel mold are connected.

In other words, if the steel mold and the lower concrete precast member are first introduced into the lower concrete precast member in a non-synthesized state, if the compression prestress required by design is introduced into the lower concrete precast member of the composite beam, 2 The introduction of additional prestresses to the lower concrete precast members, secondary or secondary, is accompanied by creep and dry shrinkage, together with the introduction of the necessary compression prestresses corresponding to the self and live loads of the synthetic beams required for field installation of the composite beams. There is an effect of compensating for prestress loss, and as shown in FIG. 4, the tensile force is introduced into the upper flange of the steel mold, thereby greatly reducing the cross section of the steel mold.

Therefore, the necessary prestress can be efficiently introduced according to the design purpose, so that the design, construction management, and quality control of the steel mold and the lower concrete precast member can be efficiently achieved, and the economical cross-sectional design of the member is possible. have.

Finally, the bridge can be completed by installing the upper slab concrete on the precast composite beam installed in the field.

5A to 5C show a case in which the precast composite beam 300 is cut into a predetermined length and manufactured.

Even in the case of the steel mold 340 as shown in Figure 5a, each steel mold (340a, 340b, 340c) having a predetermined length is connected to each other using a mechanical connecting means 350 such as bolts and plates (steel type The upper flange, the abdomen and the lower flange), the pre-flection load is not applied to the steel mold in advance, and is connected to the lower concrete precast member 310 as the pre-fabricated steel mold, the lower concrete precast members (350a, 350b, Considering the case where the lower concrete precast member is slightly bent upward by the primary prestress introduced at 350c), the lower concrete precast member is bent upward for easy connection with the lower concrete precast member. It is bent upward as much as possible.

5b shows that the lower concrete precast members 350a, 350b, and 350c are also manufactured in various shapes including a rectangular parallelepiped shape with a predetermined length, and the length of the lower concrete precast members 350a, 350b, and 350c is corresponding to the length of the steel, and the length thereof is in the longitudinal direction (L direction). When a plurality of tension members 330a are installed and tensioned and fixed, the lower concrete precast member is a state in which compression prestress is first introduced, and the segmented lower concrete precast members are installed to abut each other. If the tension member is installed in the longitudinal direction inside the tension settled after the lower concrete precast member may be in close contact with each other. Although not shown in the drawings, it is preferable to form concavities and convexities at the joint surfaces of the respective lower concrete precast members, or to use a shear key, or to apply or fill an adhesive so that the lower concrete precast members can be closely connected to each other.

Figure 5c shows the state of connecting the lower concrete precast members closely connected to each other by a rigid and tension material manufactured by mechanical connecting means such as bolts, welding and grouting connection method after the segment is manufactured, the segment in the factory The final composite beam may be manufactured by fabricating in the assembled state, transporting it on site and assembling.

If the length of the composite beam is long, it is advantageous to manufacture, transport and install the composite beam more efficiently by manufacturing it in the factory as a segmented composite beam and then transporting it to the site.

The reference numeral 330c of FIG. 3b showing the lower concrete precast member indicates tension member receiving means (such as a sheath tube) so that the tension member 330b can be installed later, and the required prestress through the additional tension member installation, tension, and fixing process. It is distinguished from the prestress introduced primarily so that it can be introduced into the second or second or more at different times, and is also used as a means for connecting each lower concrete precast member.

The precast composite beam 300, which is manufactured so that the rigid and lower concrete precast members are integrated with each other and behaves as a whole and is segmented, is brought into the field and the prestress is introduced to the secondary or the secondary or higher to obtain the required prestress. If the upper slab concrete is installed (in-place and precast upper slab) with the synthetic beam installed in the entire area, the final bridge construction can be completed.

At this time, the connection method of the composite beam and the bottom plate concrete (400, the upper bottom plate) may be synthesized by the shear connector 360, as shown in Figure 6a, as shown in Figure 6b abdominal concrete (370) ) And the bottom beam concrete 400 is also possible to embed the composite beam formed with the shear connector 360.

In the precast composite beam of the present invention, in consideration of the distribution and characteristics of the member force according to the material characteristics, the compression prestress is introduced first to the lower concrete precast member in a state in which the steel mold and the lower concrete are not synthesized. After synthesis of the mold and the lower concrete precast member, by introducing an additional prestress into the lower concrete precast member (secondary or second or higher), the prestress is introduced into the composite section of the steel mold and the lower concrete precast member. Compared with the pre-flection manufacturing method or the re-restless composite beam manufacturing method, the upper and lower flange cross-sections of the steel mold can be greatly reduced, which is economical and has the advantage of maintaining the mold height of the conventional preflex composite beam. In addition, by supplementing the time-dependent prestress loss due to creep and drying shrinkage due to the introduction of the first prestress, the construction cost is reduced by the introduction of the second prestress.

Claims (2)

Introducing a first compression prestress by using a tension member to the lower concrete precast member in a non-synthetic state with the steel mold; Manufacturing a composite beam by connecting the lower concrete precast member and a pre-fabricated steel mold; And additionally introducing at least a second or more compression prestress into the lower concrete precast member, wherein the preconcrete is segmented into a length of the entire span or a predetermined length, and then connected and manufactured. Cast composite beam manufacturing method. delete

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