KR20090022502A - Long span psc girder type rahmen bridge and its construction method using moment re-distribution - Google Patents

Abstract

Long span PSC girder type framing bridge through the moment redistribution and the construction method thereof are provided that the excessive moment to the wall is prevented. A long span PSC girder type framing bridge through the moment redistribution comprises a concrete wall body(10) of both sides, and an upper structure installed between the concrete wall bodies. The upper structure includes a PSC girder(20) and a concrete deck-plate formed in the PSC girder upper with the integrally.

Description

Long Span PSC Girder Type Rahmen Bridge and its Construction Method Using Moment Re-distribution}

The present invention relates to a structure capable of forming a prestressed concrete girder-type ramen bridge between long diameters through a moment redistribution method, and a construction technology suitable for the same, specifically, a prestressed concrete girder (hereinafter referred to as a "PSC girder"). In the construction of the ramen bridge, the moments generated by the girder and the bottom plate load are guided to the center of the bridge by appropriately redistributing the moments in the construction stage and renewing the cross-sectional shape of the walls and girders. The present invention relates to a ramen bridge and a construction method having excellent economic feasibility between long distance and low height by minimizing the parent moment and balancing the positive and negative moments acting on the bridge by secondary dead and live loads.

In recent years, the demand for bridges between low and long spans has been increasing due to frequent heavy rainfalls, rising river levels, and floods, but there is no appropriate low bridge type to meet these demands. In other words, the construction of bridges by applying multi-span bridges or by increasing the height of roads.

On the other hand, the concrete ramen bridge is used as a bridge type to be built in small rivers because it has the advantage that there is no bridge device, low mold height and easy maintenance. However, the conventional ramen bridge has a large moment, and the moment due to its own weight rapidly increases, and in particular, the moment of the point where the wall and the superstructure, that is, the girder or the bottom plate, increases rapidly, so it is generally applied to a bridge having a length of 15 m or more. Since there is a limit that it is difficult to do so, it is difficult to use it as it is with the recent bridge demand as the conventional ramen bridge.

Looking at the structural limitations that are difficult to apply the conventional ramen bridge directly to the bridge between the jijangji in more detail, first, the longer the length of the ramen bridge, the greater the moment due to its own weight. FIG. 1 shows a schematic moment diagram when a uniform distribution load is applied to a conventional ramen bridge, and Equation 1 below shows the moments (M _a , M _b ) acting at a fixed end of a wall, that is, a vertical member. Equation 2 is a moment (M _c , M _d ) acting on the point portion, Equation 3 is a moment (M _e ) acting in the center of the interval. In Equations 1 to 3 below, β is the ratio of the cross-sectional secondary moment (I _h ) of the horizontal member and the cross-sectional secondary moment (I _v ) of the vertical member, that is β = I _h / I _v , e is the height of the wall H Is the ratio of the length L to the length L, that is, e = H / L, l is the length of the length L, and w is an equally distributed load value.

As such, the moments (M _c , M _d ) acting on the point portion are proportional to the square of the length of the bridge, so if the span of the bridge doubles, the moment (M _c , M _d ) of the point portion is four times, and the temperature And considering the load due to dry shrinkage, etc. The moment (M _c , M _d ) of the point portion is increased to more than four times.

As such, the moment of the point increases, resulting in an increase in bridge height. In particular, when the bridge is constructed with concrete structure, the mold height should be designed based on the effective section considering the crack, etc., so the height between the actual bridges becomes bigger, and the increase in the weight results in the increase of the self weight. As a result, the moment of the point increases, and thus the additional increase in the height of the bridge, which is inevitably becomes a bridge having an uneconomical cross section of the height of the bridge.

Another structural limitation that is difficult to apply the conventional ramen bridge directly to the bridge between the jijangji is a difference due to the difference in the stiffness ratio of the superstructure and the wall, that is, the difference in the stiffness ratio of the girder or the bottom plate and the wall. As the height of the wall decreases in the ramen bridge between the same spaces, the moment (M _c ) acting on the point increases. In other words, the moment acting on the top of the wall becomes large. However, if the short span ramen bridge is changed to the long span bridge by increasing the length of the span as it is, the height of the wall becomes longer in the fixed state, so the height of the wall is increased. The moment due to the difference in the stiffness ratio between the plate and the wall is generated additionally, in response to this, the cross section is increased, and there is a limit to the construction of an uneconomic bridge.

As a conventional method for increasing the span of the ramen bridge, it has been proposed to introduce tension by arranging steel wires on girders forming a superstructure. However, the introduction of horizontal tension by the steel wire to the girder may be advantageous to the superstructure, but the additional moment due to the wire tension is applied to the wall causes a problem that increases the burden on the wall. In particular, since the tension force of the steel wire is eventually delivered to the wall, the tension force introduced into the center of the trunk is reduced, which also causes a problem in that the tension force is poorly introduced.

In addition, since the steel wire should be fixed to the point where the maximum parental moment occurs, that is, the point is structurally disadvantageous, and in order to reinforce the upper end of the wall on which the maximum parental moment acts, the steel wire must also be placed and reinforced in the vertical direction. There is a problem that is accompanied by economic disadvantages.

The present invention was developed to solve the above problems of the prior art, and ultimately, it is an object of the present invention to provide a ramen bridge and a construction method having excellent economic efficiency between long and short periods.

Specifically, the present invention forms a superstructure of the bridge with a PSC girder having an efficient cross section suitable for long distances, thereby greatly reducing the moment due to the weight increase and minimizing the increase in the weight due to the increase in the length of the bridge. It is an object of the present invention to provide a ramen bridge and its construction method for achieving a ramen bridge.

In addition, the present invention forms a wall that receives both the axial force and the moment in two divided sections, thereby reducing the rigidity of the wall to reduce the moment due to its own weight as well as to reduce the load due to displacements such as temperature and drying shrinkage It is an object of the present invention to provide a ramen bridge and a construction method for achieving long and low height ramen bridges by resolving excessive moments on walls that are problematic in inter-lane ramen bridges.

Furthermore, the present invention introduces a new method of construction that can redistribute the moments generated at each construction stage, so that the balance between the static and the parent can be balanced to efficiently construct the long span and low height ramen bridges. The purpose is to provide a ramen bridge with a new structure and construction method thereof.

Specifically, according to the present invention, as a ramen bridge composed of concrete walls on both sides and an upper structure provided therebetween, the upper structure has an I-shaped cross section consisting of an upper, a lower flange and a web in the middle of the span. At the point where the upper structure and the upper end of the wall meets the prestressed concrete girder (PSC girder) having a square faithful cross section and a concrete bottom plate integrally formed thereon; A bracket is formed on the top of the concrete wall and protrudes inwardly between the sections, and an end of the PSC girder is mounted on the bracket; Ramen bridge is provided, characterized in that the concrete is integrally poured to the point portion has a structure in which the upper structure and the wall is integrally rigid.

In the ramen bridge of the present invention, the wall has a structure in which the partition member is installed in the lower end thereof so that the cross section of the wall is divided into the inner side of the stem and the outer side of the stem, and the upper surface of the bracket and the PSC girder. An elastic pad may be interposed between the bottom surfaces of the end portions, and a bedding layer made of a filler may be formed on another gap portion between the top surface of the bracket and the bottom surface of the PSC girder.

In addition, in the ramen bridge of the present invention, a through hole is formed in the end portion of the PSC girder, a reinforcing tension member may be installed and fixed to the through-hole of the point concrete in the hardened state and the end of the PSC girder.

According to another embodiment of the ramen bridge according to the invention, the bottom plate may be formed on top of the PSC girder by pouring concrete together when the concrete of the point portion is poured.

In the present invention, there is provided a method for constructing such a ramen bridge.

According to the present invention, the stiffness ratio between the superstructure and the wall is increased through two divisions of the wall section, so that the moment acting on the upper end of the wall at the point is reduced, and the temperature is changed and dried due to the reduction of the secondary moment of the wall. The load caused by the displacement of the contraction, etc. is also reduced, so that it is possible to solve the excessive moment generation for the wall, which is a problem in the long-term ramen bridge.

In addition, in the present invention, the structure of the PSC girder has an I-shaped cross section consisting of an upper, a lower flange and a web in the middle of the span, and a rectangular faithful cross section at the point portion, so that the ramen bridge becomes a long span. In this case, it is possible to minimize the increase in moment due to the weight of the superstructure.

In particular, in the present invention, by redistributing the moment by adjusting the construction stage and structural shape, the moment generated by the self-weight of the superstructure to the center of the trunk to minimize the parent moment acting on the top of the wall at the point, bridge The positive and negative moments generated by secondary fixed loads and live loads due to the pavement acting after construction are balanced, and it is possible to efficiently construct long-term, low-density ramen bridges.

Next, with reference to the drawings will be described the joining structure and the construction method of joining the beam and the concrete deck according to the present invention.

2 is a schematic side view showing the state in which the wall 10 is installed. In order to construct a ramen bridge according to the present invention, first, as shown in FIG. In the present invention, the wall 10 preferably has the following structure. 3 is a cross-sectional view taken along the line A-A in FIG. 2, as shown in FIG. 3, in the present invention, the wall 10 is preferably made of a concrete wall having a structure in which the cross section of the lower part is divided into two. That is, the partition member 13 such as plywood or the like is installed in the axial direction so that the cross section of the wall 10 is divided into the interstitial inner side 11 and the interstitial outer side 12.

Since the wall 10 is a structure that receives axial force and a moment at the same time, the smaller the rigidity of the wall, the smaller the moment generated in the wall due to the change in the weight and temperature of the superstructure. Therefore, when the cross section of the wall 10 is divided into two, the cross-sectional area subjected to the axial force is maintained as it is, so that the bearing force for the axial force remains the same, but the stiffness and cross-sectional secondary moment of the two divided sections are reduced to 1/4, The ratio of the stiffness ratio between the wall and the wall, that is, the ratio of the cross-sectional secondary moment, is increased, thereby reducing the moment acting on the upper end of the wall 10 at the point portion. In addition, since the load caused by the displacement of the temperature change and the drying shrinkage is also reduced due to the reduction of the secondary moment of the cross section of the wall, it is possible to solve the excessive moment generation for the wall which is a problem in the long bridge ramen bridge. As such, it is preferable that the part divided into two parts of the wall 10 is in the range of about 0.5 to 1.0H at the lower end of the wall 10 (where H is the height of the wall).

Meanwhile, in the present invention, when the PSC girder 20, which will be described later, is mounted on the upper end of the wall 10 and is described later, both ends of the PSC girder 20 are placed and supported to support the bracket. (14) is formed.

The PSC girder 20 is mounted on the top of the constructed wall 10. 4 is a schematic side view of a state in which the PSC girder 20 is mounted. In order to prevent an increase in load and moment due to the weight of the superstructure, the PSC girder 20 preferably has the following structure. FIG. 5 shows a schematic perspective view of a PSC girder 20 according to the invention, FIG. 6A shows a cross sectional view at line BB of FIG. 5 and FIG. 6B shows a cross sectional view at line CC of FIG. 5. have. In the long span ramen bridge, since the influence of the moment due to its own weight is large, as shown in the drawing, the PSC girder 20 has an I-shaped cross section consisting of an upper, a lower flange and a web in the middle of the span. On the other hand, in the case of the point portion, the moment acting on the girder does not increase even if its own weight increases, so only the axial force on the wall is increased, so that the end of the PSC girder 20 positioned at the point portion has a square faithful cross section. . Through the PSC girder 20 having such a cross-sectional structure it is possible to minimize the increase in the moment due to the self-weight of the superstructure generated when the long-term interstitial.

In Figure 5, the member number 22 is a through-hole 22 for installing the reinforcing tension member for additional reinforcement after the concrete portion of the point as described later.

In mounting the PSC girder 20 having the cross-sectional structure as above on the top of the wall 10, the end of the PSC girder 20 is placed on the bracket 14 of the wall 10, as shown in FIG. FIG. 7 shows a detail of the circle D portion of FIG. 4, as shown in FIG. 7, in mounting the end of the PSC girder 20 over the bracket 14, the top surface of the bracket 14. And an elastic pad 23 between an end surface of the PSC girder 20 and an end surface of the bracket 14, and a different material between the upper surface of the bracket 14 and the end surface of the end of the PSC girder 20. It is preferable to have a structure which forms the bedding layer 21. Such an elastic pad 23 and the filling material serve to distribute the load directly evenly between the upper surface of the bracket 14 and the lower surface of the end portion of the PSC girder 20.

When the PSC girder 20 is mounted on the upper portion of the wall 10 as described above, the concrete 30 is poured into the point portion so that the upper portion of the wall 10 and the end of the PSC girder 20 are integrally formed to form a rigid structure. do. 8 is a schematic side view showing a state in which the concrete 30 is poured as above. As shown in the figure, when placing the concrete 30 in the point, the bottom plate 31 formed on the PSC girder 20 may be formed at the same time or may be poured concrete, alternatively PSC After installing the girder 20 and constructing the bottom plate 31 on the upper portion thereof, the concrete 30 is placed only at the point portion so that the upper structure, that is, the PSC girder 20 and the bottom plate 31 and the wall 10 The upper part of) can also be connected by hardening.

FIG. 9 is a schematic detail of the circle E portion of FIG. 8. Reinforcement 32 may be arranged to reinforce the point as shown in FIG. 8, in which case the vertical reinforcement 16 disposed in the wall 10 for a more robust rigidity of the wall 10 and the superstructure. It is also preferable to connect the reinforcing bar 32 and the point portion using a coupler 17 or by welding. In addition, it is also preferable to connect the reinforcing bars 23 arranged in the PSC girder 20 by various methods such as welding the point reinforcing bars 32.

On the other hand, if necessary, after the concrete of the branch portion is hardened, it is also preferable to penetrate the fixing portion 24 after the reinforcing tension member 24 is installed through the through hole 22 of the branch portion and the end of the PSC girder 20. At this time, in order to further increase the reinforcing effect, the reinforcing tension member 24 may be tensioned to impart a tension force.

As described above, after the installation of the concrete and the bottom plate 31 of the upper portion of the PSC girder 20 is completed, as shown in FIG. do.

Next, the moment redistribution state at each construction step will be described with reference to the moment diagram illustrated in FIG. 11. FIG. 11 shows a comparison between the moment of the conventional ramen bridge having the same specification and the moment of the ramen bridge according to the present invention. The moment of the left side is for the conventional general ramen bridge. It is about the present invention. In addition, (a) of Figure 11 is a moment diagram in the state that the load due to the weight of the upper structure, that is, the girder and the bottom plate is applied, Figure 11 (b) is a secondary fixed load by the bridge facilities such as pavement It is a moment diagram in the state which only a live load acts, and FIG.11 (c) is a moment diagram in a final use state.

As shown on the left side in FIG. 11 (a), in the case of the conventional ramen bridge, the construction of the upper structure of the bridge to install the temporary facility, such as a copper bar and cast concrete after the concrete is hardened and then the temporary facility is to be removed Moment of M _sn acts on the point part by load by structure. However, in the case of the present invention, as shown in Figure 3, the end of the PSC girder 20 is placed on the bracket 14 of the wall 10, the bottom plate in a state where the PSC girder 20 is mounted between the walls 10 If the concrete is placed on the right side of Fig. 11 (a), the concrete that is not hardened at the point does not resist the load, so the weight of the girder and the bottom plate load are _behaved like a hinge (M _sn1 = 0). ).

In the state where only the secondary fixed load and the live load act, the conventional ramen bridge and the ramen bridge of the present invention receive the same moment. Therefore, as shown in (c) of FIG. 11, the moment state in the final use state is a state in which the moment diagram shown in (a) of FIG. 11 and the moment diagram shown in (b) of FIG. In the present invention, the interstitial center moment M _p1 becomes larger than the interstitial center moment M _p in the conventional ramen bridge, but in the point moment, the point moment moment M _n1 of the present invention is the conventional ramen. It becomes smaller than the point moment M _n at the bridge.

As described above, in the present invention, by adjusting the construction stage and the structural shape, redistributing the moment, the parent moment acting on the upper end of the wall 10 at the point part by inducing the moment generated by the self-weight of the superstructure to the center of the trunk. The moment generated by the secondary fixed load and live load due to the pavement acting after the bridge construction is minimized, and the parent moment is greater than the positive moment, so the positive and negative moments are balanced when the moments for all the working loads are added together.

1 is a schematic moment diagram when a uniform distribution load is applied to a conventional ramen bridge.

Figure 2 is a schematic side view showing a state in which a wall is installed for the construction of the ramen bridge according to the present invention.

3 is a cross-sectional view taken along the line A-A in FIG.

4 is a schematic side view showing a state in which the PSC girder is mounted on a wall according to the present invention.

5 is a schematic perspective view of a PSC girder according to the present invention.

FIG. 6A is a cross sectional view taken along the line B-B of FIG. 5, and FIG. 6B is a cross sectional view taken along the line C-C of FIG.

FIG. 7 is a detail of the circle D portion of FIG. 3. FIG.

8 is a schematic side view showing a state in which concrete is poured in the point portion.

9 is a schematic detail of the circle E portion of FIG. 8.

10 is a schematic side view of the Ramen Bridge according to the present invention in a state in which vehicle traffic is allowed after installing facilities such as railings necessary for the bridge.

FIG. 11 shows the moment diagram of a conventional general ramen bridge having the same specification as the moment diagram of the ramen bridge according to the present invention.

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

10 ... wall

20 ... prestressed concrete girder (PSC girder)

30 ... concrete at the point

31 ... bottom plate

Claims (10)

As a ramen bridge composed of concrete walls 10 on both sides, and an upper structure provided therebetween, The superstructure has an I-shaped cross section consisting of an upper, a lower flange and a web in the middle of the span, and a prestressed concrete girder having a square faithful cross section at the point where the upper structure and the upper end of the wall 10 meet ( PSC girder) 20 and a concrete base plate 31 integrally formed thereon; A bracket (14) is formed on the upper portion of the concrete wall (10) so as to protrude inwardly between the sections, and an end of the PSC girder (20) is mounted on the bracket (14);  Ramen bridge, characterized in that the concrete portion 30 is integrally poured in the point portion has a structure in which the upper structure and the wall (10) is integrally rigid. As a ramen bridge composed of concrete walls 10 on both sides, and an upper structure provided therebetween, The superstructure has an I-shaped cross section consisting of an upper, a lower flange and a web in the middle of the span, and a prestressed concrete girder having a square faithful cross section at the point where the upper structure and the upper end of the wall 10 meet ( PSC girder) 20 and a concrete base plate 31 integrally formed thereon; The wall (10) has a structure in which a partition member (13) is provided inside the lower end thereof so that the cross section of the wall (10) is divided into the interplanar inner side (11) and the interplanar outer side (12); A bracket (14) is formed on the upper side of the concrete wall (10) so as to protrude inwardly between the sections, and an end of the PSC girder (20) is mounted on the bracket (14);  Ramen bridge, characterized in that the concrete portion 30 is integrally poured in the point portion has a structure in which the upper structure and the wall (10) is integrally rigid. The method according to claim 1 or 2, An elastic pad 23 is interposed between an upper surface of the bracket 14 and an end lower surface of the PSC girder 20, and another gap portion between an upper surface of the bracket 14 and an end lower surface of the PSC girder 20. Ramen bridge, characterized in that the bedding layer (24) made of a filling material is formed. The method according to claim 1 or 2, The through hole 22 is formed at the end of the PSC girder 20, Ramen bridge, characterized in that the reinforcing tension member 24 is installed and fixed in the through-hole 22 of the point concrete 30 and the end of the PSC girder 20 in the hardened state. The method according to claim 1 or 2, The bottom plate (31), when the concrete portion of the point portion 30 is poured with the concrete is ramen bridge, characterized in that formed on top of the PSC girder (20). As a construction method of the ramen bridge consisting of the concrete wall 10 on both sides, and the upper structure provided therebetween, The superstructure has an I-shaped cross section consisting of an upper, a lower flange and a web in the middle of the span, and a prestressed concrete girder having a square faithful cross section at the point where the upper structure and the upper end of the wall 10 meet ( PSC girder) 20 and a concrete base plate 31 integrally formed thereon; Constructing the concrete wall (10) in a state in which a bracket (14) protruding inward to the interior of the concrete wall (10) is formed; Lifting the PSC girder (20) to mount the PSC girder (20) between the two side walls (10) such that the end of the PSC girder (20) rests on the bracket (14); And The method of constructing a ramen bridge comprising the step of integrally pouring concrete 30 to the point portion to have a structure in which the upper structure and the wall 10 are integrally rigid. The method of claim 6, In the step of constructing the wall 10, the partition member 13 is installed inside the lower end of the wall 10 so that the cross section of the wall 10 is divided into the inner side 11 and the outer side 12 between the stems. Construction method of the ramen bridge, characterized in that. The method according to claim 6 or 7, In the step of mounting the PSC girder 20 between the two walls 10, Placing an end of the PSC girder (20) on the bracket (14) with an elastic pad (23) installed between an upper surface of the bracket (14) and an end lower surface of the PSC girder (20); The method of constructing a ramen bridge, characterized in that the bedding layer (24) is formed by filling a filler in another gap between the upper surface of the bracket (14) and the lower surface of the end portion of the PSC girder (20). The method according to claim 6 or 7, A through hole (22) is formed at an end of the PSC girder (20); After pouring the concrete 30 of the point portion, when the concrete 30 is hardened, a reinforcing tension member 24 is installed to pass through the through hole 22 at the end of the concrete 30 and the PSC girder 20. Construction method of the ramen bridge characterized in that the fixing. The method according to claim 6 or 7, When pouring the concrete 30 of the point portion, the floor plate 31 is constructed by pouring concrete so that the bottom plate 31 is integrally formed on the upper portion of the PSC girder 20 of the ramen bridge. Construction method.

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