KR200358338Y1 - Beam using a separable steel member - Google Patents

Abstract

The present invention particularly relates to a structural beam using detachable steel that can be designed in an optimal cross-section by sharing its stress with respect to the external load acting at each construction stage in bridge girders. The structural beam of the present invention is a concrete reinforcement that shares the stress of the fixed load (dead load) and the external loads loaded at each construction stage with the beam (BEAM), which is constructed by combining with the slab, with steel, PSC steel, and reinforced concrete. And a steel material attached to the beam outer surface to be detachable to both the upper or lower portion, the upper and lower portions of the neutral axis with respect to the neutral axis of the beam cross section.

Description

Structural beams using removable steels {Beam using a separable steel member}

The present invention relates to a structural beam using removable steel and a bridge construction method using the same. More specifically, the present invention relates to a bridge construction method using a structural beam that can be designed in an optimal cross section by effectively sharing a stress with respect to an external load acting on each construction stage in a bridge girder.

1A is a longitudinal sectional view of a conventional PSC beam. As shown, a PSC beam (1; prestressed concrete beam) is generated by a bending moment due to self load (including slab load and cross beam load) and common load (including secondary dead load by traffic load, median separator, pavement, etc.). In order to reduce the tensile stress of the lower part of the beam, a plurality of PSC steels 2 embedded in the lower part of the beam are tensioned by a pretension method or a post-tension method, and then fixed using the anchorage 2a to lower the beam by an external load. It is precisely the structural beam that causes the compressive stress to be introduced into the beam, corresponding to the tensile stress acting below the neutral axis.

However, if the mold height is low and the compressive stress introduced into the lower flange of the beam by the PSC steel material 2 exceeds the allowable compressive stress of the concrete, the lower flange 11c is caused by compression cracking according to the PSC beam ( 1) It could lead to destruction, and even in the case of the upper flange, if the common load accumulates and the compressive stress accumulates on the PSC beam, which exceeds the allowable compressive stress of concrete, it will seriously affect the durability and safety of the PSC beam (1). The problem has been raised.

That is, in the case of fixing the PSC steel after tension, the upper part of the beam becomes the compression part, and the compression part is designed when the compression is continuously increased by the live load such as the beam weight, the cross beam weight, the slab weight, and the secondary dead weight and traffic load. It exceeds the standard (acceptable compressive stress of concrete), which is more dangerous than the lower surface of the beam in which tensile stress is introduced by PSC steel, which can cause serious safety problems in bridge construction using PSC beam (1). Meant.

Therefore, as a means for canceling the excessive compressive stress acting on the beam upper surface conventionally, the T-type steel (3) is embedded in the upper direction of the PSC beam, as shown in the left side of Fig. To form a steel beam protruding into the upper surface by being embedded in the upper flange, or to produce a beam applying compressive force to the steel embedded by using hydraulic means so that tensile stress is generated on the upper part of the PSC beam by the steel embedded in the upper flange. Many methods are introduced.

These methods extend to both sides by the elastic modulus ratio (n = Es / Ec, where n is the elastic modulus, Es is the elastic modulus of the concrete, and Ec is the elastic modulus of the concrete) to the cross-sectional area of the steel as shown in the right side view of FIG. The concrete converted cross section 4 can resist external forces, and as a result, the neutral axis can be moved upwards, and it can be more resistant to compressive stress acting on the compression section of the beam cross section, Steel buried in such a way as to be buried inside the beam is not economical because it is not reusable, and especially after the slab is formed, the beam and the slab can be combined and resist the external force with the composite cross section. Even though it is able to resist external force even if it does not exist, there is a structural problem that it does not meet the efficient beam cross-sectional design by remaining inside the beam. have.

In addition, in order to offset the cumulative tensile stress of the lower part of the PSC beam when the conventional PSC beam is manufactured, mounted on the piers and alternating slabs, and formed on the PSC beam, additional PSC steel (secondary PSC steel) ), And the second tension and fixing work of PSC steels is not only very poor in construction but also desirable in terms of safety accidents. The problem was pointed out. This can be particularly problematic in the case of so-called IPC girders, where the PSC steel is tensioned and settled in stages according to the construction stage (beam fabrication, transport, slab formation stage). There is a need to improve construction problems in the work.

The present invention has been made to solve the above problems,

An object of the present invention is to provide a structural beam and a bridge construction method using the same, which can design the most optimal beam cross section while canceling the excessive compressive stress in the compression portion of the structural beam.

Another object of the present invention is a structural beam that can be constructed by efficient beam cross-section design without secondary tension and fixing work of PSC steel to offset the tensile stress occurring in the lower part of the structural beam according to the construction stage, and the bridge construction method using the same To provide.

1A and 1B are longitudinal cross-sectional views of a PSC beam in which a longitudinal cross-sectional view and a steel material are expressed in a concrete converted cross-section in a conventional PSC beam,

2 is a perspective view of a PSC beam according to the present invention,

3A and 3B are cross-sectional views of another embodiment of FIG. 2,

Figure 4 shows an example of the installation state of the upper and lower steels in the structural beam of the present invention,

5 is a conceptual diagram of a state in which the hydraulic means is installed on the steel of the present invention.

<Explanation of symbols for main parts of the drawings>

10: PSC beam 11a: upper flange

11b: abdomen 11c: lower flange

12: PSC steel 13: home

14a, 14b.14c: Steel 15: Folded member

16: Bolt 18: Steel receiving means

30: Gabor 40: Hydraulic means

In order to achieve the above object, the structural beam according to the present invention, for example, PSC steel is embedded, the neutral axis of the upper portion of the neutral axis based on the neutral axis of the beam cross-section consisting of the concrete upper flange, the abdomen and the lower flange, the compressive stress, When the lower part is subjected to tensile stress, the technical feature is that the steel is installed to be detachable to the upper and lower parts of the beam.

The steel is installed on the beam is completed to manufacture the beam and the steel of the present invention is installed to be detachable to the compression flange side (upper portion including the upper flange and the abdomen). In this state, when the PSC steel is tensioned, the beam is blocked up, and both ends thereof become a point, and the weight of the beam acts as a weight.

At this time, the compressive stress acting on the compressing part of the beam by the PSC steel is divided into the upper flange, the abdomen, and the steel of the present invention, so that the stress acting on the compressing part is distributed to each component as compared to before using the steel. It is effective. Furthermore, since the compression section and the steel can continue to resist the cross beam and the slab weight, the stress applied to the upper flange and the part of the abdomen of the compression section of the beam is relatively small, thereby making it optimal. It is possible to design the cross section of.

When the slab curing formed on the upper part of the PSC beam with the steel of the present invention is completed, the steel is removed. At this time, the compressive stress acts on the composite section of the beam and the slab by the amount of force that the steel is structurally added. Compression stress can be added to the furnace slab and the compression section.

However, even if the stress is added, the compressive part of the beam and the steel have received the compressive stress from the previous, so even if the stress is added, much less stress acts on the compressing part of the beam than before the steel is used. On the other hand, the slab acts by increasing the additional stress than before using the steel, but the slab acts as a beam and composite cross section, so that it can sufficiently resist the added stress.

In other words, by using a steel material, by removing it, the stress of a part of the compression part is moved to the slab. Therefore, the stress of the compression part can be made small, and as a result, the beam height can be lowered in the same area.

In addition, at any point (before tensioning the PSC steel, after some or all tensioning of the PSC steel, after cross-beaming, etc.), the arbitrary size (stresses at the top and bottom of the beam may meet the design criteria). It is also possible to reduce the compressive stress acting on the compression part of the beam by spreading the steel to both sides by using hydraulic means in the middle at any number of times (at least one or more times) in a satisfying range).

In other words, if the steel is installed and the tension force is introduced into the PSC steel, some compressive stress remains on the upper part of the beam. If the steel is opened to both sides, the compressive stress of the steel increases but the compressive stress of the compressive portion decreases. Can have

Specifically, when the tension of the PSC steel is completed, the compressive stress of the compression part is about 60 kg / cm 2. Therefore, if the steel is opened so that the compressive stress is close to 0, the stress of the compression part becomes smaller. (Afterwards, additional stress is generated by the slab's own weight, but in this case, the compression flange and the steel share and resist so as a result, Compressive stress will be less.)

In addition, when the cross beam construction is completed, the compression flange increases about 75kg / cm2. At this time, if the steel is opened so that the stress of the compression flange is close to zero, the cross beam weight acts to increase the compressive stress acting on the steel. This can further reduce the final stress of the compression unit. At this time, the compressive stress can be increased in the slab by reducing the stress of the compression part. The slab is composed of beam and composite section and acts on the secondary dead load and live load. There is no problem at all.

Preferably, after the beam fabrication, the force is not applied to the steel until tension and mounting, cross beam construction, and the pressure on the compression flange side can be adjusted by opening to both sides as needed before slab casting.

As a result, the present invention increases the stress shared by the steel by the steel, but can be reused by removing the slab after curing, thereby economically manufacturing the structural beam, and optimizing the beam cross-section as much as the stress shared by the steel.

In the case of the steel installed in the lower part of the beam, when looking at the mechanical behavior of the steel in the lower part of the beam installed, the lower part of the beam is the portion where the PSC steel is placed and the tension is introduced. Is introduced. Afterwards, the tensile stress is continuously applied to beam weight, cross beam, slab, secondary dead load and live load to offset the first compressive stress.

After the beam fabrication is completed, the steel of the present invention is installed to be detachable under the beam, and when the PSC steel is tense, compressive stress is introduced under the beam. At this time, since the tension applied to the lower flange side (lower flange and lower part of the abdomen) and the steel are also shared resistance, as a result, as much PSC steel as possible is introduced so that the maximum allowable compressive stress is introduced. There is.

After the slab curing is completed, if the steel of the present invention is removed, the composite cross section of the slab and the beam is similarly resistant to external load, and the additional compressive stress acts on the position of the steel as much as the compressive stress received by the steel. As a result, an additional compressive stress is applied to the lower part of the beam.

This has the same effect as the result of installing additional PSC steel under the beam and introducing tension in the bridge. When the steel is removed, the structural calculations show that the slab and the composite cross section make the neutral shaft more upwards, and thus the eccentricity is increased, so that the effect of the compressive stress introduced is increased. The same structural effects (additional compressive stress on the bottom of the beam) can be achieved as are the tensioning and fixing operations of the PSC steel in stages.

Tensile stress introduced into the steel material below the beam can be spread freely using hydraulic means at any time, at any size, and any number of times (at least once), similarly to the steel material on the upper surface of the beam.

In the present invention, the steel is installed at least in the compression section of the beam in consideration of the size and workability of the beam cross section, but may be additionally installed in the beam tensioning section, and both may be installed.

In order to explain the present invention more clearly and easily described in detail by the accompanying drawings the best embodiment of the present invention, the embodiment according to the present invention can be modified in various other forms, the scope of the present invention It is noted that is not limited to the embodiments described below, and can be used in both building beams or bridge girders.

Figure 2 is a perspective view of a PSC beam according to the present invention, Figures 3a and 3b shows an example in which steel is installed in the structural beam of the present invention.

Structural beam 10 of the present invention is a concrete reinforcement that shares the stress of the fixed load (dead load) and the external load loaded in each construction stage with the steel, PSC steel, reinforced concrete, the neutral axis of the beam cross section based on the neutral axis Or steels 14a, 14b, 14c attached to the beam outer surface so as to be detachable to both the bottom, top and bottom.

The structural beam 10 is a structural beam that can be installed steel (14a, 14b, 14c) of the present invention, at least bridge PSC beam, U beam, steel plate beam, steel box girder, preflex beam, leaf It can be applied to the rest preplex beam.

In the embodiment of the present invention will be described based on the PSC beam.

The PSC beam may be applied to both a pretension method and a posttension method. In the present embodiment, a post tension PSC beam is described as an example.

The post tension PSC beam 10 used herein has an upper flange 11a formed on the upper side, a lower flange 11c formed on the lower side of the abdomen 11b, and a plurality of inside the lower flange 11c. Two sheaths are built in, and each of the sheaths is a structural beam into which a PSC steel 12 is inserted. At this time, as is known, the sheath tube is bow-shaped bowed downward as shown in Figure 1a.

At this time, at least one groove 13 is formed at the side edge of the upper flange 11, and the groove 13 may be installed in such a manner that the steel 14a of the present invention is inserted.

The steel 14a is made of Seg steels of approximately 3-4M so as to facilitate the work by using a steel bar having a predetermined thickness, if there is a product manufactured to a predetermined length as a steel bar, or easy to work, and several Seg Steels can be installed while connecting to each other, and if necessary, the connecting portion can be welded or connected to the connecting member.

In this embodiment, the Seg steel having a rectangular cross section is installed on a continuous basis. The steel member 14a is equipped with a plurality of folding members 15 having holes 15a formed therein. The steel material 14a is firmly fixed to the upper flange 11a by the bolt 16 penetrating through the hole 15a and being fixed to the fastener 17 of the upper flange 11a.

Thus, the steel 14a is installed on the upper flange (compression flange) of the PSC beam, and the compressive stress acting on the beam upper part in its own weight before slab curing when the beam is manufactured, transported, mounted on the piers, and when the cross beam is installed. To share.

In FIG. 2, the steel 14a is installed on both sides of the upper flange, which is the compression flange, but as shown in FIG. 3a, the bolt 16 and the folding member 15 are connected to the upper portion of the upper abdomen 11b and the upper flange 11a. It can be installed using, and a plurality of steel (14a) up and down may be installed on one side by the steel accommodating means (18), such as ㅗ type folding member. In addition, the groove portion may or may not be provided in the beam for accommodating the steel material 14a. This steel 14a may also be equally installed at the connection of the lower part of the abdomen 11b and the lower flange 11c.

Furthermore, as shown in FIG. 3B, a steel mounting portion 19 having a step difference is formed on the connection portion between the upper part of the abdomen 11b and the upper flange 11a, and using the bolt 16 and the folding member 15 in the steel mounting portion. It can also be installed.

Although the folding member 15 and the bolt 16 are used to fix the steel, they are to prevent the deviation of the position when the steel shares the stress, and the end of the steel can be supported as shown in FIG. It is preferable to form the supporting portion 11d on which the end of the portion can be supported.

In addition, the steel of the present invention is installed in the longitudinal direction of the beam irrespective of the formation position, at least one or more (14b, 14c) may be divided and installed by distinguishing the longitudinal section with a large cross-sectional force and the small longitudinal direction. That is, as shown in FIG. 4, since both ends of the beam generate less bending moment, one bone 14b is provided in the longitudinal direction of the beam, and the middle portion of the beam has at least one bone 14c or more because the bending moment is large. It can be installed additionally, and eventually a plurality of steel (14b, 14c) can be installed in the beam.

At this time, the steel (14b) is formed so that the abdomen (11b) of the beam end is formed thick, the abdomen (11b) of the portion except the end is formed so that the end is supported on the stepped portion 20 generated, and later To be installed through the cross beam that can be installed.

In addition, since the other steel 14c does not extend to both ends of the beam, in order to be able to support an end spaced from the beam end, it may be supported by a cross beam 30 installed in a direction crossing the beam between beams. And, if the cross beam is not available to put a separate support to be able to support the end of the steel.

Furthermore, when the steel material installed on the PSC beam 10 is manufactured and installed as a Seg steel, a separation part (S, a connection part of the Seg steel material, etc.) for positioning the hydraulic means 40 at a predetermined portion is formed as shown in FIG. 5. In the laid state, when the hydraulic means (hydraulic jack, jack clamp, etc.) is installed in the separation unit (S), and the hydraulic means is operated, the steel contacting the hydraulic means receives the compressive stress in the direction in which the hydraulic means acts and the steel Since the end is supported by the beam end, the cross beam or the support part as shown in FIG. 4, the tensile stress is generated in the concrete around the steel due to the stress. This tensile stress means that the additional tensile stress is introduced to the upper portion of the beam by the steel in addition to the installation of the steel, thereby canceling the excessive compressive stress generated on the upper portion of the beam.

Also in the case of the steel is installed in the lower portion of the beam as shown in Figure 3b and 3c can also be such that the compressive stress is introduced to the lower portion of the beam by using the hydraulic means.

When the slab is cured and formed on the PSC beam 10 provided with the steel of the present invention, the PSC beam is integrated with the slab. Therefore, the cross section of the slab and the PSC beam can be combined with the additional external load, and finally, the steel 14a installed as shown in FIG. 2 is removed, so that it can be reused as steel installed in another bridge.

Bridge construction method according to the present invention is installed on the pier or bridge with a beam for a bridge including a steel attached to the outer surface of the beam to be detachable to both the upper or lower, upper and lower portions of the neutral axis based on the neutral axis of the beam cross section 1 step to do; Before forming a slab on the bridge beam, using the hydraulic means in the middle of the steel to generate tensile stress in the bridge beam integrated with the steel; And forming a slab on the bridge girders, and then separating the attached steel materials.

The first step is to manufacture a girder for bridges, the steel material of the present invention is installed on the beam. Installation of the steel is a process of installing in the longitudinal direction on the upper flange and the lower flange as shown in Figures 2, 3a and 3b, and fixing the steel to the upper flange using the folding member and the bolt.

In the second step, in the beam for bridges in which steel is installed, hydraulic means is installed in the clearance portion S of the steel as shown in FIG. 4, and the hydraulic means is operated to push the steel to both sides, or vice versa. This is a process for generating tensile stress on the top or bottom of the beam. This two step is preferably such that the slab is carried out after curing and before curing.

The third step is to separate the steel installed after the slab is cured so that it can be reused later.When the slab is cured, the external load (various live loads, secondary dead loads, etc.) that the composite section of the slab generates later occurs And the separated steel is reused as steel for other structural beams.

As described above, according to the present invention, since the use of expensive PSC steel can be reused, it is possible to reduce the compressive stress of the compression flange when used in the structural beam having a low profile, and the secondary PSC steel is installed below the beam. The same structural effect as the post-tension and fixation can be obtained by separation after installation of the steel of the present invention installed in the lower part of the beam, thereby making it possible to manufacture a structural beam having excellent workability and having an economical and efficient cross section.

Claims (2)

In the beam for the structure (BEAM) composited with the slab, It is a concrete reinforcement that shares the stress against the fixed load (dead load) and external loads by construction stages with the steel, PSC steel, and reinforced concrete, and is applied to both the upper or lower, upper and lower neutral shafts based on the neutral axis of the beam section. Structural beams using detachable steel, characterized in that it comprises a steel material attached to the outer surface of the beam to be detachable. The method of claim 1, wherein the steel is formed in the longitudinal direction on the outer surface of the beam while both ends are supported, the steel is bolted to the beam using a folding member so as to be in close contact with the beam, when dismantling the bolt Structural beams using removable steel, characterized in that separated from the beam can be reused later.