JP2010144512A - Structure near intermediate supporting point of continuous i-beam bridge - Google Patents

Abstract

[PROBLEMS] To reduce steel weight, man-hours, and construction costs, reduce concrete placement work on site, enable rapid construction, and reduce transportation costs to the site.
In a continuous I-girder bridge composed of an I-girder 30 and a floor slab provided with an upper flange 32, a lower flange 34, a web 36, and a vertical stiffener 38, and supported by one or more intermediate fulcrums. A space is provided between the upper flange 32 and the lower flange 34 in the region surrounded by the lower flange 34, the web 36, and the vertical stiffener 38 in the vicinity of the fulcrum. By integrating the plate 40 with a stopper that is not connected to the upper flange, local buckling of the lower flange 34 is prevented and the lateral buckling strength is improved.
[Selection] Figure 6

Description

  The present invention relates to a civil engineering structure such as a bridge, and more particularly to a structure near an intermediate fulcrum of a continuous I-girder bridge.

  As illustrated in FIGS. 10 and 11, a large negative bending moment M is generated near the intermediate fulcrum 12 of the continuous I girder bridge 10. Due to this bending moment, a compressive force acts on the lower flange 134 of the I girder 130, so that as shown in the enlarged cross section of the I girder 130 in FIGS. 12 and 13, local buckling (FIG. 12), Lateral buckling (FIG. 13) can occur. In particular, when a high-strength steel or the like is applied to a continuous I girder bridge having a relatively long span, such a problem becomes significant. 12 and 13, 116 is a floor slab, 132 is an upper flange of the I-girder 130, and 136 is a web.

As prior art 1 for this, in the vicinity of the intermediate fulcrum,
(1) Increasing the thickness of the lower flange 134,
(2) The gap between the horizontal beam and the horizontal groove is reduced and arranged closely.
There are measures such as.

  Further, Patent Document 1 is cited as the prior art 2. The bridge continuous girder described in Patent Document 1 includes a steel girder body that has upper and lower flanges and a web, extends in the bridge axis direction, and is supported by one or more intermediate fulcrums. Around the intermediate fulcrum of the main body, reinforced concrete in which all or part of vertical and horizontal reinforcing bars are embedded is placed so as to follow the web, and the vertical reinforcing bars extend vertically and vertically Ends are respectively connected to the upper and lower flanges, the horizontal rebar extends in the direction of the bridge axis and perpendicular to the vertical rebar, and the supported area around the intermediate fulcrum is defined by the upper and lower flanges, the web and the vertical stiffener. In the formed recess, the reinforcing bars are reinforced with reinforcing bars arranged in a lattice pattern parallel to the web and concrete filled and filled to cover the reinforcing bars.

  Further, as a girder structure of a continuous girder bridge using a pair of parallel I-girder, Patent Document 2 and Patent Document 3 include a reinforcing plate (Patent Document 2) and a concrete plate (Patent Document 3) between lower flanges near a fulcrum. ) Is fixed and reinforced as a box-shaped cross section.

  Moreover, as a structure of the box girder bridge, Patent Document 4 describes that the entire internal space of the steel box girder in the area around the intermediate fulcrum is filled with concrete and reinforced.

JP 2002-266317 A JP-A-11-81240 Japanese Patent Laid-Open No. 11-148110 JP 2004-176344 A

  However, the prior art 1 has the following problems.

  (1) When the plate thickness of the lower flange is increased, the steel weight will increase significantly, and the work by welding and bolting for each cross section will become difficult, resulting in an increase in man-hours and cost. Become.

  (2) In the case where the gaps such as the cross beams and the horizontal grooves are arranged closely and densely arranged, the number of the cross beams, the horizontal grooves and the like increases, so that the steel weight and the man-hour increase, and the construction cost increases.

  The prior art 2 has the following problems.

  In the prior art 2, it is necessary to connect the upper and lower ends of the vertical reinforcing bar to the upper and lower flanges directly or by welding or the like via a short reinforcing bar and a coupler. In general, since the gap between the upper and lower flanges of the girder bridge is about 2 to 3 m, the vertical rebar also has a length of about 2 to 3 m. The operation of directly welding long reinforcing bars of 2 to 3 m to the upper and lower flanges is complicated and difficult, and it is difficult to ensure accuracy. Also, when connecting short rebars via couplers, it is necessary to weld short rebars and connect longer rebars via couplers, which not only increases the number of man-hours, but also the positions and angles of short rebars. High accuracy is required. Furthermore, complex concrete placement work on site and a long curing period are required. In addition, if the concrete is to be placed in a factory, transportation to the site becomes difficult.

  In addition, all of the techniques described in Patent Documents 2 to 4 need to form a box girder cross section, which requires more man-hours and costs than the I girder cross section.

  The present invention has been made to solve the above-mentioned conventional problems, and can reduce the steel weight, man-hours and cost, reduce the concrete placing work on site, enable rapid construction, and transport to the site. The object is to reduce costs.

  The invention according to claim 1 of the present invention is a continuous I-girder bridge constituted by an I-girder and a floor slab provided with an upper flange, a lower flange, a web, and a vertical stiffener, and supported by one or more intermediate fulcrums. A space is provided between the upper flange and the lower flange near the intermediate fulcrum, the web, and the lower flange in the area surrounded by the vertical stiffener, and the precast plate is placed on the upper flange. By the structure of the I-girder in the vicinity of the intermediate fulcrum in the continuous I-girder bridge, which is integrated with a non-displacement stopper to prevent local buckling of the lower flange and improve lateral buckling strength, Is a solution.

  In the invention according to claim 2 of the present invention, the precast plate is provided with a box cutting portion, and the precast plate provided with the box cutting portion is connected to a lower flange, a web, a vertical stiffening member near the intermediate fulcrum. Place on the lower flange of the area surrounded by the material, place the stopper on the lower flange so as to be in the boxed part, and place the filling material on the boxed part, preload with the lower flange The plates are integrated.

  In the present invention, the lower structure of the I girder and the precast plate are integrated. As a result, even when a large negative bending moment is generated near the middle fulcrum of the continuous I-girder bridge and a large compressive force acts on the lower flange, local buckling and lateral buckling of the lower flange are effectively prevented, and the load bearing capacity is reduced. It can be greatly improved. Therefore, unlike the prior art 1, it is not necessary to increase the plate thickness of the lower flange or to reduce the spacing between the cross beams and the lateral grooves and arrange them densely. Can be reduced.

  Further, in the present invention, since the concrete placement on site is only placement of a filler such as non-shrink mortar into the box opening part, it is compared with the on-site concrete placement method as in prior art 2. Work on site is greatly reduced and the effects of creep and drying shrinkage are reduced. Moreover, since the curing period of concrete also decreases, rapid construction becomes possible, and the effect of reducing construction cost and construction period can be obtained. If the prior art 2 is performed up to the concrete placement in the factory, the transportation to the site becomes difficult. In the present invention, since the I girder and the precast plate can be separately transported to the site, the transportation cost to the site is reduced as compared with the conventional technique 2.

The perspective view which shows the structure of the I girder near the intermediate fulcrum concerning the 1st reference example regarding this invention Same side view Side view showing another example of construction A plan view showing an example of the shape and arrangement of the box opening part Side view of I-girder structure near intermediate fulcrum according to second reference example of the present invention The perspective view which shows the structure of the I girder near the intermediate fulcrum according to the first embodiment of the present invention. Same side view Side view showing another example of construction Side view of the structure of the I-girder near the intermediate fulcrum according to the second embodiment of the present invention Side view showing an example where the first and second reference examples are arranged on a continuous I girder bridge Side view showing an example in which the first and second embodiments are arranged on a continuous I girder bridge Front view showing local buckling of the lower flange near the intermediate fulcrum of a continuous I-girder bridge Front view showing lateral buckling near intermediate fulcrum of continuous I-girder bridge

  DETAILED DESCRIPTION Reference examples and embodiments of the present invention will be described below in detail with reference to the drawings.

  A first reference example relating to the present invention is shown in FIG. 1 (perspective view) and FIG. 2 (side view). FIGS. 1A and 2 show the structure of the I-girder 30 near the intermediate fulcrum 12 in the continuous I-girder bridge 10 (see FIG. 10). The I-girder 30 is composed of an upper flange 32, a lower flange 34, and a web 36. It is configured. The precast board 40 shown in detail in FIG. 1 (B) is, for example, a precast RC board, a precast PC board, a precast FRP board, or the like, but other materials may be used as long as they satisfy predetermined performance. I do not care. Hereinafter, the precast board 40 provided with the box opening part 42 will be described as an example.

  A construction example of the first reference example on site is shown in FIG.

  (1) As shown in FIG. 3A, the I girder 30 is temporarily placed with the lower surface of the lower flange 34 facing upward, and a stud 50 for slippage prevention is installed on the lower flange 34 of the I girder 30.

  (2) As shown in FIG. 3 (B), the pre-cast plate 40 is installed so that the box opening portion 42 is aligned with the stud 50 installed on the lower flange 34 of the I girder 30.

  (3) As shown in FIG. 3C, a filler 52 such as a non-shrink mortar or a curing agent is placed on the box opening portion 42, and the lower flange 34 of the I-girder 30 and the precast plate 40 are integrated and synthesized. Let

  (4) After curing for a predetermined period, as shown in FIG. 3 (D), the I girder 30 is installed upside down.

  In this reference example, the box opening portion 42 has a rectangular shape as shown in FIG. 4 (A). However, it is sufficient that the stopper 50 can be disposed in the inside, and FIGS. 4 (B), (C) and (D). An arbitrary shape can be applied as illustrated in the modification example.

  Further, the installation order of the studs 50 may be changed in consideration of workability and the like. For example, it may be installed in a factory in advance, or after the precast plate 40 is installed on the lower flange 34 of the I girder 30, it may be installed in the box opening portion 42.

  On the other hand, when using the precast plate 40 without the box opening 42, the precast plate 40 is disposed under the lower flange 34 in the vicinity of the intermediate fulcrum 12 as in the second reference example shown in FIG. You may make it integrate with the volt | bolt 56 grade | etc.,.

  From the above, a composite structure in which the lower flange 34 of the I girder 30 and the precast plate 40 are integrated is obtained. As a result, a large negative bending moment is generated in the vicinity of the intermediate fulcrum 12 of the continuous I-girder bridge 10, and even when a large compressive force acts on the lower flange 34, local buckling and lateral buckling of the lower flange 34 are effectively prevented. The load bearing capacity can be greatly improved.

  In addition, since the concrete placement on site is only the placement of the filler 52 or the like into the box opening portion 42, the work on site is greatly reduced as compared with the on-site concrete placement method, and creep. And the effect of drying shrinkage is reduced. In addition, the concrete curing period is reduced as compared with the on-site concrete placing method, so that rapid construction is possible.

  Next, a first embodiment of the present invention is shown in FIG. 6 (perspective view) and FIG. 7 (side view). 6 (A) and 7 show the structure of the I-girder 30 near the intermediate fulcrum 12 in the continuous I-girder bridge 10 (see FIG. 11). The I-girder 30 includes an upper flange 32, a lower flange 34, a web 36, It consists of a vertical stiffener 38. The precast board 40 shown in detail in FIG. 6B is, for example, a precast RC board, a precast PC board, a precast FRP board, or the like, but other materials may be used as long as they satisfy predetermined performance. I do not care. Hereinafter, the precast board 40 provided with the box opening part 42 will be described as an example.

  The construction example in the field of 1st Embodiment is shown in FIG.

  (1) As shown in FIG. 8 (A), an I-girder 30 is installed on site, and a stud 50 for preventing slippage is installed on the lower flange 34 of the I-girder 30.

  (2) As shown in FIG. 8 (B), the pre-cast plate 40 is installed so that the box opening portion 42 is aligned with the stud 50 arranged on the lower flange 34 of the I-girder 30.

  (3) As shown in FIG. 8C, a filler 52 such as a non-shrink mortar or a curing agent is placed in the box opening portion 42, and the lower flange 34 of the I-girder 30 and the precast plate 40 are integrated and synthesized. Let

  In the present embodiment, the box opening portion 42 has a rectangular shape as in the first reference example. However, any shape can be applied as long as the stud 50 can be disposed therein.

  Further, the installation order of the studs 50 may be changed in consideration of workability and the like. For example, it may be installed in a factory in advance, or after the precast plate 40 is installed on the lower flange 34 of the I girder 30, it may be installed in the box opening portion 42.

  On the other hand, when using the precast plate 40 without the box opening 42, the precast plate 40 is disposed on the lower flange 34 in the vicinity of the intermediate fulcrum 12 as in the second embodiment shown in FIG. You may integrate with the volt | bolt 56 grade | etc.,.

  From the above, a composite structure in which the lower flange 34 of the I girder 30 and the precast plate 40 are integrated is obtained. As a result, a large negative bending moment is generated in the vicinity of the intermediate fulcrum 12 of the continuous I-girder bridge 10, and even when a large compressive force acts on the lower flange 34, local buckling and lateral buckling of the lower flange 34 are effectively prevented. The load bearing capacity can be greatly improved.

  In addition, since the concrete placement on site is only the placement of the filler 52 or the like into the box opening portion 42, the work on site is greatly reduced as compared with the on-site concrete placement method, and creep. And the effect of drying shrinkage is reduced. In addition, the concrete curing period is reduced as compared with the on-site concrete placing method, so that rapid construction is possible.

  FIG. 10 shows an arrangement example of the first and second reference examples 60 in the vicinity of the intermediate fulcrum 12 regarding the continuous I girder bridge 10, and FIG. 11 shows an arrangement example of the first and second embodiments 62. The structure of the I girder 30 in the vicinity of the intermediate fulcrum 12 according to the present invention may be arranged over the entire negative bending region as shown in FIG. Alternatively, as shown in FIG. 11 (B), it may be arranged only in a severe part of the negative bending region. In the figure, 14 is an end fulcrum, 16 is a floor slab, and M is a bending moment distribution.

DESCRIPTION OF SYMBOLS 10 ... Continuous I girder 12 ... Intermediate fulcrum 14 ... End fulcrum 16 ... Floor slab 30 ... I girder 32 ... Upper flange 34 ... Lower flange 36 ... Web 38 ... Vertical stiffener 40 ... Precast board 42 ... Box opening part 50 ... Stud (stop)
52 ... Filler 54 ... Adhering material 56 ... High strength bolt 60 ... Structure near the intermediate fulcrum of the first and second reference examples 62 ... Structure near the intermediate fulcrum of the first and second embodiments M ... Bending moment

Claims (3)

In a continuous I-girder bridge composed of I-girder and floor slab with upper flange, lower flange, web, vertical stiffener, and supported by one or more intermediate fulcrums,
A space is provided between the upper flange and the lower flange in the vicinity of the intermediate fulcrum, the web, and the lower flange in the region surrounded by the vertical stiffener, and the precast plate is disposed.
By integrating the lower flange and precast plate with a stopper that is not connected to the upper flange,
An I-girder structure in the vicinity of an intermediate fulcrum in a continuous I-girder bridge characterized by preventing local buckling of the lower flange and improving lateral buckling strength.   The precast plate is provided with a boxing portion, and the precast plate provided with the boxing portion is arranged on the lower flange in the vicinity of the intermediate fulcrum, the web, and the lower flange surrounded by the vertical stiffener. The stopper is disposed on the lower flange so as to be in the box-cutting portion, and a filler is placed on the box-cutting portion to integrate the lower flange and the precast plate. Structure of the I-girder near the intermediate fulcrum in the described continuous I-girder bridge.   A continuous I-girder bridge having an I-girder structure near an intermediate fulcrum according to claim 1 or 2.

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