JP2003253621A - Continuous beam structure for continuing existing simple beam bridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continue even an existing simple beam bridge becoming a nonlinear shape in a passage of a main beam. <P>SOLUTION: An existing bridge B becomes a nonlinear shape by dislocating the passage of a central main beam 10 of a span S<SB>1</SB>and an inside main beam 10 of its adjacent span S<SB>2</SB>. A reinforced concrete horizontal beam 20 extending in the bridge width direction is constructed so as to cross with an end part of the main beam 10 of the two spans S<SB>1</SB>and S<SB>2</SB>. A stud (a stress transmitting member) is implanted by welding in a web 14 of the end part of the respective main beams 10, and is embedded in concrete of the horizontal beam 20. Thus, the respective main beams 10 and the horizontal beam 20 are connected so that stress can be transmitted, in its turn, the mutual two main beams forming the nonlinear passage can mutually transmit the stress. Thus, the bridge B is formed as a continuous beam structure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a structure in which an existing simple girder bridge is continuous.

[0002]

2. Description of the Related Art Many existing bridges have a simple girder structure for economic reasons and technical reasons. In recent years, there are many cases where main girders are connected as seismic retrofitting work for such existing simple girder bridges. FIG. 6 shows an example of this main girder connection construction method. Two main girders 1 adjacent to each other in the bridge axis direction are shown.
Connection plate 3 of upper and lower three steps between webs 2 of A and 1B (simple girder)
A, 3B and 3C are laid over. In particular, the upper connecting plate 3A extends long through the vertical stiffener 4 of each main girder 1A, 1B. As a result, the behavior of the two main girders 1A and 1B with respect to the live load and the dead load after connection can be brought close to the behavior as a continuous girder, and the earthquake resistance can be improved. In addition, the long life of heavy traffic (the current live load has increased compared to the design due to the revision of the road bridge specification), environmental improvement of the surrounding area by reducing vibration and noise, maintenance free by no joint Many advantages such as conversion can be obtained.

[0003]

In order to carry out the above-mentioned conventional main girder connecting method, there is a constraint that the two main girders to be connected have to be in a substantially straight line. In the case of a non-linear shape, that is, (1) when the main girders to be connected are largely displaced in the bridge width direction, (2) when the main girders to be connected are greatly bent, (3 ) When at least one of the main girders to be connected is a curved curve girder, it was physically impossible to connect these main girders with a connecting plate. Therefore, even if the need for consolidation was high, we had no choice but to give up implementation.

[0004]

In order to solve the above problems, the present invention has a steel main girder for each span, and the main girders between adjacent spans are non-linear ( These main girders are displaced from each other or the corners are bent, or at least one of the main girders is a curved girder). Between the adjacent spans, a transverse beam made of reinforced concrete extending in the bridge width direction is constructed so as to intersect with the ends of the main girders. A stress transmitting member is provided at an end of each main girder so as to be embedded in the concrete of the horizontal beam. The transverse beam and each main girder can transmit stress via the stress transmitting member. As a result, even if the street of the main girder is non-linear, it can be surely made continuous, and a continuous girder bridge can be obtained.

Here, the stress transmitting member is preferably a stud welded to the web of the main girder. As a result, the structure can be simplified, and the stress can be surely transmitted.

[0006] It is desirable that the horizontal beam includes a plurality of prestressed steel materials that are strained to form prestressed concrete. As a result, the resistance to the torsional moment can be increased and the beam cross section can be reduced. It is desirable that some of these prestressed steel materials extend through the web of the main girder in the bridge width direction.

It is desirable that an outer cable made of prestressed steel material be tensioned and bridged between the upper portion of the main girder near the intersection with the horizontal beam and the upper portion of the horizontal beam. As a result, a part of the tensile stress acting on the upper part of the main girder or the cross beam can be transmitted through this outer cable, and local stress concentration does not occur at the joint between the main girder and the cross beam. be able to.

In the vicinity of the intersection of the main girder with the horizontal beam, a recess defined by the upper and lower flanges and a web is filled with reinforced concrete so as to be continuous with the horizontal beam. On the other hand, it is preferable that the first reinforcing bar includes a first reinforcing bar that extends vertically and a second reinforcing bar that extends perpendicularly thereto and horizontally along the web, and that the upper and lower ends of the first reinforcing bar are connected to the upper and lower flanges.
This makes it possible to alleviate a sudden change in cross section between the main girder and the lateral beam, and reliably prevent local stress concentration on the joint. It is preferable that the second reinforcing bar extends inside the horizontal beam and also serves as a reinforcing bar of the horizontal beam. As a result, the cross beam and the reinforced concrete can be reliably integrated.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows the arrangement of the main girders 10 in the existing simple girder bridge B before being made continuous. Each main girder 10 includes a web 11 and upper and lower flanges 12,
And I-section steel with 13 and. Web 1
Vertical stiffeners 14 are provided at intervals on both side surfaces of 1.

The main girder 10 is erected so as to extend in the bridge axis direction for each of the spans S ₁ , S _2, ... Divided by the bridge pier 40 (shown in FIG. 2). Each of the spans S ₁ , S ₂ ...
A plurality of main girders 10 are arranged in parallel in the bridge width direction. In the bridge B of this embodiment, the three main girders 10 are arranged in parallel in the span S _1, and the four main girders 10 are arranged in parallel in the span S ₂ adjacent to the span S _{1 at} intervals smaller than the span S _1. There is.

The main girder 1 in each span S ₁ , S _2, ...
The end portions of 0 are steel end fulcrums transverse beams (not shown.
~ Same in FIG. ). The end portion of the end fulcrum lateral girder is bolted to the vertical stiffener 14 directly above the bearing (see FIG. 2) (on the most end side of the main girder 10).

[0012] What the main girder 10 of the bridge both widthwise sides of the span S1, S ₂ adjacent to is arranged in alignment with one another, as is in a straight line. On the other hand, the main girder 10 at the center of the span S _{1 in} the bridge width direction and the two main girders 10 on the middle side of the span S _{2 in} the bridge width direction are deviated from each other in axis line, and the passage is non-linear. The present invention constructs a continuous girder by connecting the main girders 10 having such non-linear streets to each other.

A continuous girder structure in which the simple girder bridge B is connected will be described. As shown in FIG. 1, in the continuous bridge B, a horizontal beam 2 made of prestressed concrete is provided at each intermediate fulcrum, that is, at a boundary between adjacent spans S ₁ , S ₂ ...
It is constructed so that 0 extends in the bridge width direction. The cross beam 20 intersects with each main girder 10. That is, the horizontal beam 2
The end of each main girder 10 is embedded in the concrete 21 of 0. As shown in FIGS. 2 and 4, a stud 15 (stress transmission member) having an appropriate length is welded and implanted in the web 11 of the buried portion. Stud 15 is web 11
Are arranged over the entire area in the vertical direction. With these studs, stress can be reliably transmitted between the main girder 10 and the lateral beam 20.

The cross beam 20 will be described in detail. As shown in FIGS. 2 to 4, in the concrete 21 of the horizontal beam 20, ordinary reinforcing bars 22 extending in the axial direction of the lateral beam 20 (bridge width direction) and ordinary reinforcing bars extending in the width direction of the lateral beam 20 (bridge axial direction). A plurality of 24 bars are arranged.

The reinforcing bar 22 is arranged at a position where the cover thickness of the concrete 21 is secured. The reinforcing bar 22 arranged on _one span S ₁ side intersects with the end of the main girder 10 of the span S ₁ , and the reinforcing bar 22 arranged on the other span S ₂ side,
It intersects the end of the main girder 10 of the span S ₂ . The web 11 at the end of each main girder 10 is formed with a through hole 11 a through which the reinforcing bars 22 pass. A stirrup bar 26 is arranged so as to surround all the reinforcing bars 22 in the axial direction of the cross girder 20, and in the vicinity of each main girder 10, only a plurality of reinforcing bars 22 penetrating the main girder 10 are surrounded. A stirrup streak 26 is also provided.

Further, in the concrete 21 of the horizontal beam 20, a PC cable (prestressed steel material) 23 which is parallel to the reinforcing bar 22 and extends in the axial direction (bridge width direction) of the horizontal beam 20.
And a PC steel material (prestressed steel material) 25 extending in the width direction (bridge axis direction) of the cross beam 20 in parallel with the reinforcing bar 24.
Multiple bars are arranged. The PC cable 23 is arranged inside the concrete 21 rather than the reinforcing bar 22. Of these PC cables 23, the P that is arranged closer to the span S ₁
C cable 23 crosses the end of the main girder 10 that span _{S 1,} PC cable 23 arranged on the span _{S 2} closer crosses the end of the main girder 10 that span _{S 2} ing. Each main girder 1
No. 0 web 11 has a through hole 1 through which the PC cable 23 passes.
1b is formed. As shown in FIG. 1, these PCs
The cable 23 is strained in its extending direction, and both ends thereof are projected from the end surface of the lateral beam 20 and fixed to the fixing member 28A provided on this end surface. by this,
In the concrete 21, the transverse direction of the transverse beam 20 (width direction of the bridge)
Pre-stressed along with.

Similarly, as shown in FIGS. 1 and 3,
PC steel material 25 extending in the width direction of the cross beam 20 (bridge axis direction)
Are projected from the side surface of the lateral beam 20 and are fixed in a fixing state to a fixing member 28B provided on this side surface. Thereby, the prestress in the width direction (bridge axis direction) is also applied to the concrete 21.

The extending direction, the bar arrangement position, the number of the reinforcing bars 22 and 24 and the prestressed steel members 23 and 25 of the cross beam 20 are not limited to the above, and may be various according to the necessity of ensuring the design strength. A mode (for example, the extending direction is oblique or vertical) is adopted.

As shown in FIGS. 1 and 3, in the upper part of the cross beam 20 and in the vicinity of the main girder 10, as the prestressed steel material extending in the bridge axis direction, a PC outer cable is used instead of the PC steel material 25. 27 are arranged. The cable 27 outside the PC is tensioned in the extending direction, and one end of the cable 27 is a horizontal beam 2.
0 is fixed to the fixing member 28B on the side surface opposite to the main girder 10 in the vicinity thereof, while the other end is exposed from the cross beam 20 and provided on the upper side of the web 11 of the main girder 10 in the vicinity. It is fixed to the fixing member 29. As a result, stress transmission between the upper portions of the main girder 10 and the lateral beam 20 is also performed via the PC cable 27.

As shown in FIG. 1, in the vicinity of the intersection of the main girder 10 with the horizontal beam 20, a reinforced concrete 3 is provided in a recess 10a formed by the web 11 and the upper and lower flanges 12 and 13.
0 is filled. The concrete 31 of the reinforced concrete 30 is seamlessly connected to the concrete 21 of the transverse beam 20. The outer surface of the concrete 31 is flush with the edges of the flanges 12 and 13 or the vertical stiffener 14. Depending on the strength required for the design, the concrete 31 may be cast thinner or thicker than the flanges 12 and 13 and the vertical stiffener 14. The end surface of the reinforced concrete 30 on the side opposite to the horizontal beam 20 is defined by the vertical stiffening member 14, but the present invention is not limited to this, and the end face may be exposed between two adjacent vertical stiffening members 14. It may be located.

As shown in FIG. 2, inside the concrete 31, there are a reinforcing bar 32 (first reinforcing bar) perpendicular to the flange, and a reinforcing bar 33 (second reinforcing bar) horizontal to the flange along the web 11. Are buried in each. The plurality of vertical reinforcing bars 32 are arranged at intervals in the extending direction of the main girder 10. The upper and lower ends of each vertical rebar 32 are abutted against the upper and lower flanges 12 and 13, respectively, and are connected by arc welding or spot welding.

The plurality of horizontal reinforcing bars 33 are arranged at intervals vertically. A large number of these horizontal reinforcing bars 33 are arranged in the upper part of the main girder 10 (the region where tensile stress acts above the neutral axis of the girder cross section) rather than in the lower part (the region where compressive stress acts). There is. The horizontal reinforcing bar 33 arranged on the upper side of the main girder 10 may be thicker than the horizontal reinforcing bar 33 arranged on the lower side, or one having high strength may be used. Each horizontal reinforcing bar 33 also enters the inside of the horizontal beam 20,
It also serves as the width direction reinforcing bar 24 of 0. As a result, the cross beam 20 and the reinforced concrete 30 and thus the main girder 10 are more surely integrated. The vertical stiffener 14 of the main girder 10 is formed with a through hole 14a through which the horizontal reinforcing bar 33 passes.

The concrete 21 of the cross beam 20 is filled with the end fulcrum cross beam (not shown). In this end fulcrum transverse girder, the width direction reinforcing bars 24, 33 of the transverse beam 20,
A through hole through which the PC steel material 25 and the PC cable 27 are passed is formed.

Further, in the continuous bridge B, a floor slab made of cast-in-place concrete is used in place of adjacent spans S ₁ , S ₂ ... 50 are provided. The floor slab 50 is spliced onto the concrete 21 of the horizontal beam 20. Further, on the pier 40, an intermediate fulcrum support 41 is provided for each end of each main girder 10. (Note that the support 41 for the intermediate fulcrum is provided at an intermediate position in the width direction of the horizontal beam 20.
You may make it support the edge part of each main girder 10 via. )

A construction procedure for making the bridge B continuous will be described. First, the stud 15 is welded to the web 11 of the main girder 10. Further, the reinforcing bars 22, 24, 26, 32, 33 and the prestressed steel members 23, 25, 27 are arranged. When arranging, through holes 11a, 11b, 14a are opened in the main girder 10 in advance. (The through-holes are also opened in the above-noted end fulcrum lateral girders.) Further, a form (not shown) for the transverse beam 20 and the reinforced concrete 30 is installed. In the formwork,
The fixing members 28 and 29 are attached, and the ends of the prestressed steel members 23, 25 and 27 are stopped. In this embodiment, since the end face of the reinforced concrete 30 on the side opposite to the transverse beam 20 is defined by the vertical stiffening member 14, the vertical stiffening member 14 is used as a form material for the opposite side end face. Can be used as, and a dedicated form material is unnecessary. (When the opposite end face is located between the two vertical stiffeners 14, the form material for the opposite end face is installed at this position.)

Then, the concrete 21, 31 is placed in the formwork.
To place. After curing the concrete 21 and 31, the formwork is removed. And the prestressed steel materials 23, 25,
Tension 27 to prestress concrete 21. After that, after temporarily blocking the traffic on Bridge B,
The expansion device is removed and the concrete of the floor slab 50 is cast in place. Further, while supporting the main girder 10 with the jack, the bearing for the simple girder is replaced with the bearing 41 for the continuous girder. If it is not necessary to consider the traffic during the construction of the horizontal beam 20, the concrete of the floor slab 50 may also be placed together in the step of placing the concrete 21 and 31. Also,
The replacement of the bearing 41 may be performed at an early stage or an intermediate stage of the continuous construction.

The operation of the continuous bridge B will be described. For example, it is assumed that a downward live load acts on the main girder 10 at the center of the span S ₁ . Since the end portion of the main girder 10 is restrained by the cross beam 20, a negative bending moment is generated there, and this is transmitted to the cross beam 20. At this time, the stress can be reliably transmitted to the cross beam 20 by the stud 15 at the end of the main girder 10. Further, the tensile stress transmitted between the upper portions of the main girder 10 and the horizontal beam 20 can also be transmitted via the PC outer cable 27, and is locally applied to the joint portion between the main girder 10 and the horizontal beam 20. It is possible to prevent stress concentration from occurring. Further, the main girder web 11 near the horizontal beam 20
Since the reinforced concrete 30 is filled so as to be continuous with the horizontal beam 20, the sudden cross-sectional change between the main girder 10 and the horizontal beam 20 can be alleviated, and the local stress concentration on the joint can be further enhanced. It can be surely prevented. The vertical reinforcing bars 32 of the reinforced concrete 30 can exert a large strength by restraining the upper and lower flanges 12 and 13, and the horizontal reinforcing bars 33 can exert a sufficient proof stress against tensile stress. Thereby, sufficient strength can be exerted against the negative bending moment.

In the transverse beam 20, the bending moment
Is the torsional moment and the span S ₁With the main girder 10 in the center
Is transmitted from both joints of the horizontal beam 20 to both sides in the axial direction.
It At this time, the concrete 21 of the cross beam 20 is
Being prestressed by the less steel material 23, 25
Therefore, it is possible to exert a large resistance to the above-mentioned twist.
You can Therefore, the cross section of the cross beam 20 can be made small.
And weight reduction, and reduction of horizontal force acting on the pier during an earthquake
Can be achieved.

The torsional moment in the transverse beam 20 is transmitted as a negative bending moment to the ends of the main girders 10 at the joint between the two main girders 10 on the inner side of the span S ₂ . At this time, similarly to the case of the main girder in the center of the span S ₁ described above, the stress can be surely transmitted by the stud 15 of the main girder 10 on the middle side of the span S ₂ , and particularly, regarding the tensile stress of the upper part, The PC cable 27 enables more reliable transmission, and the reinforced concrete 30 ensures that stress concentration can be alleviated.

In this way, the adjacent spans S ₁ , S ₂
Even if the main girder 10 of is not aligned, the stress acting on the main girder 10 of the _one span S ₁ is reliably transmitted to the main girder 10 of the other span S ₂ via the cross beam 20. be able to. Therefore, the bridge B behaves like a continuous girder. As a result, earthquake resistance can be improved, a bridge can be reliably prevented, and the life of heavy traffic can be extended. Further, since the horizontal beam 20 is made of concrete, it is possible to reduce the weight of the member to be carried into the site as compared with the case where it is made of steel, and the workability at the site can be improved.
Further, since the rigidity of the end portion of the main girder, which is the intermediate fulcrum after the connection, is increased, it is possible to significantly reduce vibration and noise when the vehicle is running.

The present invention can be applied to all cases where the main girders between adjacent spans are not aligned in a straight line. That is, it is not limited to the case where the main girders between the adjacent diameters are deviated from each other, and even if the main girders are bent or one or both of the main girders are curved girders, By constructing an intersecting concrete cross beam, stress can be reliably transmitted through this cross beam, and it can behave as a continuous girder.

Further, the present invention can be variously modified. For example, instead of the studs, a large number of reinforcing bars penetrating the main girder web may be embedded in the lateral beam, and this may be used as a stress transmitting member between the main girder and the lateral beam.

[0033]

As described above, according to the present invention,
Even if the street of the main girder of the existing simple girder bridge is non-linear, construct a concrete horizontal beam that intersects these main girders and transmit stress between the horizontal beam and each main girder via the stress transfer member. By doing so, the main girders can be reliably made continuous, and a continuous girder bridge can be obtained. As a result, it is possible to improve earthquake resistance, prevent falling bridges, and reduce vibration and noise. A stud is welded to the web at the end of the main girder to be embedded in a lateral beam, and this is used as the stress transmitting member, whereby the structure can be simplified and the stress can be surely transmitted.

By introducing prestress to the transverse beam, resistance to a torsional moment can be increased, the cross section of the beam can be reduced, and the weight can be reduced and the horizontal force at the time of earthquake acting on the pier can be reduced. .

An outer cable made of prestressed steel is bridged between the main girder and the upper portion of the cross beam, whereby a part of the tensile stress acting on the upper portion of the main girder or the cross beam is transmitted through the outer cable. It is possible to prevent local stress concentration from occurring at the joint between the main girder and the cross beam.

By filling reinforced concrete in the recesses defined by the upper and lower flanges of the main girder and the web so as to be continuous with the cross beam, it is possible to mitigate a sudden change in cross section between the main girder and the cross beam. It is possible to reliably prevent local stress concentration on the joint. Horizontal second of the above reinforced concrete
By extending the reinforcing bar inside the transverse beam, the transverse beam and the reinforced concrete can be reliably integrated.

[Brief description of drawings]

FIG. 1 is a perspective view showing a bridge according to an embodiment of the present invention in a state after being made continuous.

FIG. 2 is a sectional view of the bridge taken along line II-II in FIG.

3 is a cross-sectional view of the bridge taken along line III-III in FIG.

FIG. 4 is a cross-sectional view of the bridge taken along line IV-IV in FIG.

FIG. 5 is a perspective view of a main girder of the bridge before being made continuous.

FIG. 6 is a perspective view of a bridge subjected to a conventional connecting method.

[Explanation of symbols]

B Bridge S ₁ , S ₂ Span 10 Main girder 10a Recess 11 Web 11a, 11b Through hole 12 Upper flange 13 Lower flange 14 Vertical stiffener 15 Stud (stress transmission member) 20 Side beam 21 Concrete 22, 24 Ordinary rebar 23 PC Cable (prestressed steel material) 25 PC steel material (prestressed steel material) 26 Stirrup bar 27 Cable outside PC (prestressed steel material) 28A, 28B, 29 Anchoring member 30 Reinforced concrete 31 Concrete 32 Vertical reinforcing bar (1st reinforcing bar) 33 Horizontal reinforcing bar (2nd reinforcing bar) ) 40 pier 41 bearing 50 floor slab

Claims (7)

[Claims] 1. A structure in which an existing simple girder bridge in which steel main girders are erected for each span and the main girders between adjacent spans are non-linear is continuous, Between adjacent spans, a horizontal beam made of reinforced concrete extending in the bridge width direction was constructed so as to intersect with the end of each main girder. A continuous girder obtained by connecting an existing simple girder bridge, characterized in that a stress transmitting member is provided so as to be embedded, and the transverse beam and each main girder can transmit stress through the stress transmitting member. Construction. 2. The stress transmitting member is a stud welded to the web of the main girder.
A continuous girder structure that is a continuation of the existing simple girder bridge described in. 3. The cross beam comprises a plurality of prestressed steel materials which are strained, and thereby prestressed concrete is constituted.
A continuous girder structure that is a continuation of the existing simple girder bridge described in. 4. The existing simple girder bridge according to claim 3, wherein several of the plurality of prestressed steel members extend through the web of the main girder in the bridge width direction. Continuous digit structure. 5. An outer cable made of prestressed steel is tensioned and bridged between an upper portion near the intersection of the main girder and the horizontal beam and an upper portion of the horizontal beam. A continuous girder structure in which the existing simple girder bridge according to any one of claims 1 to 4 is continuous. 6. A reinforced concrete is filled in a recess defined by upper and lower flanges and a web so as to be continuous with the horizontal beam in the vicinity of an intersection of the main girder with the horizontal beam. 6. A first reinforcing bar extending horizontally along the web and a second reinforcing bar horizontally extending along the web, wherein upper and lower ends of the first reinforcing bar are connected to upper and lower flanges. A continuous girder structure that is a continuation of the existing simple girder bridge described in. 7. The continuous girder structure according to claim 6, wherein the second reinforcing bar is extended to the inside of the horizontal beam and doubles as a reinforcing bar of the horizontal beam.