KR20000041822A - Complex bridge composed of represtressed box girder - Google Patents

Abstract

PURPOSE: A complex bridge composed of a represtressed box girder is provided to enhance bending resistance and torsion resistance and to be applied to various types of bridges. CONSTITUTION: A bridge is in a box shape by being formed with a steel reinforcing concrete slab(1) and one between a steel frame and a steel plate. The bridge is composed of more than one steel girder(2) and a box concrete(3) supporting the steel girder by being installed over a lower flange(2a) of the steel girder. In the box concrete, many tendons(5) are installed to prestress the box concrete. The tendons are also installed in a web concrete(3b) at regular intervals to prestress the web concrete. Thereby, the stress concentration of concrete is buffered.

Description

Leafless Box Girder Composite Bridge

The present invention is different from the conventional Represtressed PreFlex (hereinafter referred to as "RPF") I girder composite bridge type I girder, which is a structural unit of the box girder composite type as a structural unit The present invention relates to a type bridge and a construction method thereof, and more particularly, to a leafless box girder composite type bridge which is economical, stable and constructable when manufactured in a two-chamber, three-chamber box girder.

In general, in composite bridges, the stresses on steel beams and deck concrete under the specified loading conditions must satisfy the conditions below the allowable stress. In this case, there is no problem in a simple beam, but a negative bending moment due to dead or live load acts on the point portion of the continuous beam to generate tensile stress. In order to process the tensile stress generated in the bottom plate concrete, it is necessary to introduce the prestress due to the rising or falling method of the point portion, the tension of the PC steel bar, etc., and thus the design and construction tend to be complicated.

In general, the design of continuous composite bridges such as two span bridges and three span bridges is regarded as composite in the range of (+) bending moment and non-synthesis in the range of (-) bending moment. I design it. At this time, the tensile stress is generated in the concrete deck of the (-) bending moment portion, which causes cracks in the concrete deck. In order to prevent this, in the conventional composite bridge design and construction as described above, in order to suppress the crack progression, the prestressing by the tension material is added to the axial direction of the concrete deck plate portion to allow the tensile stress acting on the concrete deck. It can be controlled within.

Here, the RPF I-girder composite type is a reinforced concrete slab 101 having a constant effective width as shown in Figure 1, and the steel girder 102, the upper flange is synthesized and supported on the slab 101, The lower flange of the steel girder 102 and the lower flange concrete 103 and the abdominal concrete 104 are respectively installed on the upright beams, and the tendon 105 is installed in the lower flange concrete 103. Here, the I-type steel girder and the PC strand supporting the slab have a non-bonded structure, and the tensile stress of the lower flange concrete is generated by re-tensioning using the non-bonding tendon to the lower flange concrete of the preflex bridge. It is the bridge which suppressed it.

The structure is low in shape and ensures stability during use due to the maximum load during construction, and can suppress the occurrence of concrete cracks in the lower flange, while the significant process density and reinforcement of the transverse support device under the preflex load There is a problem that can not be applied to the installation of long sections, bridges, curved bridges because it is required, because vibration is generated. In addition, stress on the lower concrete is applied.

Preplex composite type is a bridge that combines type I girder with reinforced concrete. Compression prestress is introduced to concrete surrounding steel tensile flanges in advance to offset tensile stress caused by dead and live loads. On the other hand, the structure has a low profile, while the lower flange concrete of the currently constructed bridge is severely cracked, so the maintenance cost according to crack repair and reinforcement is increased, and the process density is required in the case of pre-plex load.

As described above, the preflex bridge and the RPF composite bridge can cause lateral buckling if precision construction is not performed, and the lack of torsional rigidity implies a problem of causing vibration for bridges, curved bridges, long bridges, and high-speed loads. have.

The P.C I beam bridge is a structure in which a P.C strand is bonded to a reinforced concrete slab, and is a post tension bridge that reduces the moment of the constant moment section by using the PC steel wire and the steel bar. This structure has a relatively high crack safety factor, suitable for a span of about 20m to 30m, a low cost of construction, and an easy construction, whereas the structure has high mold height, can be conducted before and after installation, and continuous maintenance. There is a problem in that it is disadvantageous in travelability and in seismic design.

The PC box type is a non-adhesive combination of PC strands to reinforced concrete slabs, and is made of boxes to increase cross-sectional stiffness, and the PC strands are appropriately arranged and applied by post tension, and applied according to the construction method of FSM, FCM, It is a bridge built by ILM, MSS, etc. This structure has a low mold height and has the advantage of suppressing the occurrence of cracks in the lower flange concrete, but is prone to cracking in the prestressed anchorage, disadvantageous installation of curved bridges, complicated construction relationships, and long construction periods. There was this.

The steel box girder bridge is a structure in which a concrete slab is coupled to a steel girder, which is mainly used for a long bridge because of its rigidity, and an appropriate span has a length of about 50 m in a simple beam and about 60 m in a continuous beam. This structure is of high quality, easy to install, good aesthetics, and suitable for curved bridges and social bridges, while high in construction, corrosion, and excessive maintenance costs. There is a problem that the top plate cracks due to excessive deflection.

Accordingly, the present invention has been made to solve the above-mentioned problems, by introducing the pre-stressing by the preflex to the connection form of the box girder or I-girder and synthesized with the concrete slab to increase the flexural rigidity and torsional rigidity after completion The purpose of the present invention is to provide a releasless composite bridge that can be prevented from lateral buckling and can be applied to long span bridges, continuous bridges, bridges, and high-speed railway bridges.

The present invention also provides a restressless girder composite bridge for adding prestressing by tensioning material in the axial direction to the prestressing method for compressing the lower concrete by the preflex in the field condition or when the cross section is insufficient. There is a purpose.

It is another object of the present invention to provide an economical and stable leafless girder composite bridge.

1 is a cross-sectional view showing the configuration of a leafless I-girder composite type bridge according to the prior art.

2A to 2F are construction sequence diagrams of a leafless box girder composite bridge according to the present invention;

Figure 3 is a basic cross-sectional view showing an embodiment of the composite bridge of the leafless box girder according to the present invention.

Figure 4 is a two-section basic cross-sectional view showing the application state of the leafless box girder according to the present invention.

Fig. 5 is a two-threaded basic cross-sectional view showing an application state of a leafless box girder according to the present invention.

Figure 6 is a basic section of a three column type showing the application state of the leafless box girder according to the present invention.

Figure 7 is a first modified exemplary view of a leafless box girder composite bridge according to the present invention.

Figure 8 is a second modified example of the leafless box girder composite bridge according to the present invention.

Figure 9 is a third modified exemplary view of a leafless box girder composite bridge according to the present invention.

Fig. 10A is a fourth modified example of the leafless box girder composite bridge according to the present invention;

10B is a fifth modification of a leafless box girder composite bridge according to the present invention;

11 is a sixth modification of the leafless box girder composite bridge according to the present invention;

12 is a seventh modification of the leafless box girder composite bridge according to the present invention;

13A to 13C are structural diagrams of a RP-BOX girder composite type having a steel girder or a steel plate-shaped cross section at the point of maximum moment in the axial direction in a leafless box girder composite type bridge according to the present invention;

Fig. 14 is a schematic diagram showing a cross section example of a conventional leafless type I girder composite type calculation;

Fig. 15 is a schematic view showing a cross section example for a leafless box girder composite type calculation of the present invention.

FIG. 16 is a simplified comparative view used for comparing the torsional stiffness of FIGS. 14 and 15. FIG.

* Explanation of symbols for the main parts of the drawings

1: reinforced concrete slab 2: steel girder

3: box concrete 4: load balancing concrete

5, 5 ': tendon 6: reinforcement

7: torsion reinforcing member 8: cross-section reinforcing steel sheet

9: single reinforcing material 12: deck plate

The present invention to achieve the above object, the reinforced concrete slab having a predetermined width; It is installed and supported every predetermined span of the slab, the upper flange is synthesized in each of the slab span, the lower flange is formed of one of the continuous steel frame or steel sheet to form a box shape, the steel frame or steel sheet One or more steel girders loaded with a vertically downward preflex load; And it is provided over the entire length of the lower flange of the steel girder to provide a leafless box girder composite bridge including the box concrete for supporting the steel girder.

In addition, the present invention is a reinforced concrete slab having a predetermined width; At least one steel girder installed and supported at every predetermined span of the slab, the upper flange of which is synthesized in the respective slab spans, and a single reinforcing material is installed on the lower flange to form a box shape; Sectional force reinforcing plate continuously installed on the upper flange of the steel girder; A tendon installed to prestress the slab; And a box concrete supporting the steel girders installed over the entire length of the upright beams and the lower flanges of the steel girder, thereby providing a leafless box girder composite bridge for treating the continuous bridge parent section.

In order to prevent the lower part of the existing I-type girder composite type bridge from being separated and deteriorating stability and stiffness, the present invention having the characteristic configuration as described above has a closed cross section connected to the lower part as shown in FIGS. In this way, the torsional stiffness is increased by more than 37 times to solve the problem of low rigidity and instability of the existing bridge. If required by each site requirement, prestressing by tension material may be applied in addition to the prestressing method of compressing the lower concrete by the preflex.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings of FIG. 2.

The leafless box girder composite bridge according to the present invention is implemented to have sufficient torsional rigidity and stability. The present invention is mainly applied to long bridges, bridges, continuous bridges, and high-speed railway bridges, and the structure thereof is as follows.

The bridge of the present invention has a reinforced concrete slab (1) having a predetermined width, and is installed and supported for each predetermined span of the slab, the upper flange (2a) is synthesized in the span of each slab (1), the lower flange (2b) is formed of one of a continuous steel frame or steel sheet to form a box shape, one or more steel girder (2) is loaded with a vertical downward preflex load on the steel frame or steel plate, and the lower portion of the steel girder (2) It is composed of box concrete (3) installed over the entire length of the flange (2a) to support the steel girder (2).

Here, the steel girder 2 has an I-shaped cross section, and is divided into a plurality of threads or a plurality of boxes depending on the width of the bridge. For example, when the bridge width is 13m or less, the steel girder 2 is composed of one chamber, two chambers of 13-18m, and twin boxes of 18-25m.

In addition, the lower flange 2b has a structure in which only a vertical downward preflex load is loaded, but prestressing may be applied in the axial direction or the perpendicular direction of the axial direction.

The box concrete (3) may be divided into a lower flange concrete (3a), the abdominal concrete (3b), in this embodiment the abdominal concrete (3b) on the outer peripheral surface of the upright beam of the steel girder (2) to a predetermined thickness It is installed structure. In this structure, painting work to prevent corrosion on the inner surface of the upright beam of the steel girder 2 should be performed.

In the present embodiment, the structure in which the abdominal concrete is poured only on the outer circumferential surface of the upright beam of the steel girder 2 is not limited thereto, and the inner concrete 3b 'shown in phantom in FIG. 3 is formed of the steel girder 2. In the upright beam inside) can also be cast to a predetermined thickness, at this time, the painting work of the steel girder (2) is not necessary. In addition, when considering the internal workability, the abdominal concrete 3b may not be installed on the upright beam of the steel girder 2.

A lower flange concrete 4 having a thickness of about 20 to 40 cm is installed on the upper portion of the lower flange 2b of the steel girder 2, and 10 cm is suitable as a thickness of the most preferred embodiment.

A plurality of tendons 5 are installed in the inside of the box concrete 3 to apply prestress to the box concrete 3, and the tendons 5 are also disposed on the abdominal concrete 3b installed on the outer circumferential surface of the upright beam of the steel girder 2 at regular intervals. It is installed to reduce the stress concentration by allowing prestressing. The number and position of the prestressing tendon 5 can be changed according to the cross-sectional force.

Referring to the modified structure of the basic cross-section of the present invention configured as described above are as follows.

The bridge shown in Fig. 3 shows a one-chamber girder composite bridge with one box concrete 3, and is mainly used for bridges having a small distance (13 m or less).

The bridge shown in Fig. 4 shows a basic section of a two-mold type, showing a structure in which two girders 2 are connected by box concrete 3 in succession, and have a bridge having a width of 18 to 25 m in general. Mainly applies to

The bridge shown in Fig. 5 is a two-sided cross-sectional structure in which an intermediate girder 2 'is installed on one box concrete 3, and the bridge is mainly used for a bridge of 13-18 m. Abdominal concrete 3b is not installed on the upright beams of the intermediate girders 2 '. The two-threaded basic cross section is more stable compared to the two main cross section.

The bridge shown in FIG. 6 shows a basic section of a three columnar shape, showing a structure in which two girders 2 are connected by box concrete 3 in succession. This is usually applied to bridges with a width of more than 25m and is mainly used for socializing.

On the other hand, when the cross-sectional force of the lower flange is insufficient, as shown in Figure 7, the reinforcing material 6 is mounted to the lower flange (2b) of the portion that meets the upright beam of the steel girder (2), the reinforcing material (6) Box concrete (3) in which the lower flange (2b) included is installed to reinforce the cross-sectional force. Moreover, the abdominal concrete 3b provided in the upright beam of the said steel girder 2 has a structure in which the tendon 5 is not provided.

When the torsional rigidity of the box concrete cross section is insufficient, as shown in FIG. 8, the reinforcement 6 is mounted on the lower flange 2b of the site where the steel girder 2 meets the upright beam. Box concrete (3) in which the lower flange (2b) included is installed to reinforce the cross-sectional force. In addition, the torsion reinforcement member 7 is installed in the inner box space of the steel girder 2 in an X shape to support the box concrete 3 and the steel girder 2 to reinforce the torsional rigidity of the box section.

If the cross-sectional force of the upper and lower flanges 2a and 2b of the steel girder 2 is not appropriate, as shown in FIG. 9, the continuous continuation over the entire length of the upper and lower flanges 2a and 2b of the steel girder 2 is performed. A sectional force reinforcing steel sheet 8 is provided to reinforce the sectional force of the upper flange 2a. At this time, it is also installed in the upper reinforcing slab (1), such as tendon (5) installed in the hub flange concrete (3a) to facilitate load distribution. However, tendons 5 are not installed in the abdominal concrete 3b.

Meanwhile, modifications of the present invention will be described with reference to FIGS. 10 to 12.

In the modified example of the present invention, as shown in Fig. 10a, the upper surface of the upper flange (2a) of the steel girder (2) is provided with a sectional reinforcing steel sheet (8) continuous over the entire length, the lower flange (2b) A single reinforcing material 9 is installed at each site where the beam meets the upper and lower flanges 2a and 2b so that the upper and lower tension reinforcement is not necessary. The box girder structure is removed.

The preflex box girder composite type shown in FIG. 10B is composed of a single flange of a lower flange 2b of the steel girder 2 instead of a continuous steel plate, and no tendons are added to only the single lower flange 2b. It has a structure in which the box concrete 3 is provided.

The box girder of FIG. 11 is formed of a steel plate in which the upper flange 2a of the steel girder 2 is continuous, and the lower flange 2b is provided with a continuous steel plate over the entire length, and meets the upright beam of the steel girder. The reinforcing material 6 is provided in the lower flange 2b. In addition, in order to improve the internal workability, the concrete is poured into only the lower flange 2b of the steel girder 2 without installing the abdominal concrete 3b on the upright beam of the steel girder 2.

The structure of the box girder of FIG. 12 is a box girder installed in a section in which a parent moment of a continuous bridge acts. The upper surface of the upper flange (2a) of the steel girder 2 is provided with a continuous cross-sectional reinforcing steel sheet 8 over the entire length, the tendon (5 ') is installed on the reinforced concrete slab (1). The lower flange 2b is formed of a single flange instead of a continuous steel plate, and a single lower flange 2b is provided with a reinforcing material 6, and a tendon 5 is not added to the lower flange concrete 3a. This makes it easy to distribute the load in a continuous bridge.

On the other hand, in the box girder composite bridge structure of the present invention as described above, as the axial configuration of the upper or lower steel, as shown in Figure 13a to Figure 13d, respectively, using a steel sheet, a steel plate / frame, a steel sheet or a deck plate Can be installed economically.

That is, the steel girder 2 shown in FIG. 13A shows an example in which the lower flange 2b is made of one steel plate, which is most excellent in torsional rigidity and stability.

The steel girder 2 shown in FIG. 13B forms through-holes 11 at predetermined intervals in the longitudinal direction in the center of the lower flange 2b formed of steel sheet, and the steel frame or deck plate in the through-holes 11. The example in which (12) is properly installed is shown.

The steel girder shown in FIG. 13C forms a through hole 11 in the longitudinal direction in the center portion of the lower flange 2b formed of steel sheet, and the steel frame or deck plate 12 is formed only in the center portion of the through hole 11. It shows an example of installation.

The steel girder shown in FIG. 13D is an example in which holes are formed in two central portions of the lower flange 2b formed of steel sheet, showing the most economical structure.

The structure of the steel girder shown in Figure 13a to 13d is a structure that can sequentially reduce the manufacturing cost, these structures can be applied to the appropriate bridge in consideration of economics and construction.

A cross-sectional example for calculating a conventional leafless type I girder composite type is as shown in Fig. 14, and Fig. 15 shows a cross-sectional example for a leafless box-type compound-shaped compound type calculation of the present invention. 16A and 16B are comparative views used for the torsional stiffness comparison, which simplifies the cross section used in FIGS. 14 and 15. FIG. 16A shows an open section of a type I girder, and FIG. 16B is a schematic view showing a closed section of a box girder. Thus, the data in Table 1 was obtained in accordance with the cross-sectional example for calculation described above.

As shown in the comparative example of the numerical calculation of the invention according to Table 1, the flexural stiffness increased by 16%, and the torsional rigidity increased by 3700% or more. That is, in general, the difference in torsional stiffness between the box section (closed section) and the open section can be up to about 40 times, and all of the assumed values in this simplified calculation are assumed to be disadvantageous to the stiffness comparison. Unreasonable assumptions did not apply.

Next, the construction method of the present invention will be described.

First, as shown in FIG. 2A, the I-shaped steel girder 2 is mounted on a simple beam or a continuous beam, and the beam and the steel girder 2 are welded by a shear connecting material. Then, the steel sheet is attached to the lower flange (2b) of the steel girder 2 to form a box girder and the reinforcement for giving a temperature gradient, and after installing the formwork in the lower flange concrete 3a placing position Install tension material using steel wire and vinyl pipe. And camber management is performed.

After performing the step, as shown in Figure 2b by using a hydraulic device or the like to load the preflex load on the steel girder, the concrete is poured into the formwork to steam curing. At this time, the safety load and deformation of the buckling are measured, and the steam curing temperature is managed.

After the step, after removing the preflex load as shown in FIG. 2C, the introduced concrete stress is examined, and as shown in FIG. 2D, the work is tensioned by using a tension member pre-installed in the concrete placing process in the formwork. Manage tension after doing this.

Next, as shown in FIG. 2E, the rebarless box girder composite bridge is completed by laying the concrete after placing the upper reinforcing bar and performing abdominal concrete quality control.

Figure 2f shows a live load on the composite bridge completed construction.

The present invention described above is not limited to the above-described embodiments and drawings, and various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those who have

As described above, according to the present invention, the steel beams synthesized in the concrete slab in the steel composite continuous bridge has a box structure to increase longitudinal, transverse bending stiffness and torsional stiffness compared to conventional girder bridges, Compared with steel, it is economical for PC box girder bridge.

In addition to the increase in the torsional rigidity of the box structure, the stability and wind resistance / shockproof stability due to the increase in the bending / lateral stiffness are increased, thereby improving the performance and durability of the bridge. In addition, the energy is saved due to the vertical upward force of the preflex bridges and the cracks are controlled by tensioning within the allowable stress of the concrete slab due to the steel and the tension of the steel slab and tension material at the joint of the continuous bridge. It has the effect of increasing the linking effect by the synthetic effect of the site.

Claims (17)

Reinforced concrete slabs with a predetermined width; It is installed and supported every predetermined span of the slab, the upper flange is synthesized in each of the slab span, the lower flange is formed of one of the continuous steel frame or steel sheet to form a box shape, the steel frame or steel sheet One or more steel girders loaded with a vertically downward preflex load; And Box concrete installed over the entire length of the lower flange of the steel girder to support the steel girder Leafless box girder composite bridge comprising a. The method of claim 1, The lower flange concrete is installed in a predetermined thickness on the lower flange of the steel girder is further included, The lower flange is pre-stressed box girder composite bridge, characterized in that pre-stressing is further applied in the axial direction, axial direction perpendicular to the axial direction. The method of claim 2, Leafless box girder composite bridge, characterized in that the lower flange concrete thickness is 20 ~ 40cm. The method of claim 1, And the box-shaped steel girder is continuously installed to have a predetermined number of molds in the bridge width. The method of claim 1, And at least one intermediate girder is provided for dividing the inside of the box-shaped steel girder so as to have a predetermined number of actual shapes. The method according to any one of claims 1 to 5, The box concrete further comprises a plurality of tendons installed to apply prestress therein. The method according to any one of claims 1 to 5, And a reinforcing box girder composite bridge further comprising a reinforcing member installed at an upper portion thereof to reinforce the cross-sectional force of the lower flange of the steel girder. The method of claim 7, wherein And a reinforcing box girder composite bridge further comprising a reinforcing member installed in an inner space of the box section to reinforce the torsional rigidity of the steel girder. The method of claim 1, And a continuous steel plate which is continuously installed on the upper flange of the steel girder to increase its cross-sectional force. The method of claim 9, A leafless box girder composite bridge further comprising tendons embedded in the slab and the box concrete. The method of claim 1, The upper flange of the steel girder is formed of a continuous steel plate, the leafless box girder composite bridge characterized in that the box concrete is poured only on the lower flange of the steel girder to improve the internal workability. The method of claim 1, Reinforced box girder composite bridge, characterized in that the abdominal concrete of a predetermined thickness is further placed, bonded to the inner circumferential surface of the steel girders. The method of claim 1, The through-hole box girder composite bridge, characterized in that the through-hole is formed at predetermined intervals in the longitudinal direction in the center of the lower flange of the steel girder. The method of claim 13, A leafless box girder composite bridge provided with any one of a steel frame and a deck plate at predetermined portions of a plurality of through holes formed in the lower flange. The method of claim 13, A leafless box girder composite bridge in which any one of a steel frame and a deck plate is installed at a central portion of a plurality of through holes formed in the lower flange. The method of claim 1, And at least one portion of the upper or lower concrete of the steel girder is prestressed by an external preflex load. Reinforced concrete slabs with a predetermined width; One or more steel girders installed and supported at predetermined intervals of the slab, the upper flanges of which are synthesized in the respective slab spans, and having a single reinforcement installed on the lower flanges to form a box shape; Sectional force reinforcing plate continuously installed on the upper flange of the steel girder; A tendon installed to prestress the slab; And Box concrete which is installed over the upright beam and the lower flange of the steel girder to support the steel girder Leafless box girder composite bridge comprising a.