JP3798371B2 - Steel plate web bridge and its erection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel plate web bridge and a construction method thereof.
[0002]
[Prior art]
Steel plate web bridges using steel plate webs and prestressed in upper and lower floor slab concrete are known. In particular, corrugated steel web bridges are equipped with lightweight corrugated steel webs that can reduce the weight of the girders and the web does not restrain the axial force of the concrete when prestressing is introduced into the upper and lower floor slab concrete. It has excellent characteristics such as easy prestress introduction into the floor slab.
[0003]
The corrugated steel web bridge is used for both I-girder and box-girder bridges, and is constructed by the overhanging construction method, extrusion construction method, and other construction methods. Manufactured with precast blocks and cast-in-place concrete blocks.
[0004]
For example, as a means for constructing a lightweight and economical bridge utilizing the features and superiority of the overhanging construction method, there is a construction method of a corrugated steel web bridge and a corrugated steel web girder bridge (see, for example, Patent Document 1). .
[0005]
Although a box girder bridge using a corrugated steel web and a pretension / external cable is also conceivable, it is not appropriate as a means for suppressing the girder height.
[0006]
Note that the precast girder is limited to a maximum girder length of about 25 m due to transport restrictions.
[0007]
On the other hand, as a technique for applying post compression to the upper edge of the PC bridge and reducing the girder height span ratio, a so-called bi-prep girder is known. Bi-pres is an abbreviation for bi-pressing system, and is a compound word of a prefix “Bi-” meaning “two” and a pre-stressing system (for example, Non-Patent Document 1). reference.).
[0008]
This technique is a press stressing system that combines a conventional post tension system or pre-tension system with a post compression system that compresses and fixes a PC steel material in concrete and applies tensile prestress to the concrete.
[0009]
The principle diagram of the bi-pre system is shown in FIGS. As shown in FIG. 14 (a), the concrete girder 100 that is simply supported at both ends exhibits the bending stress shown in FIG. 14 (b) due to its own weight. In the figure, + indicates compressive stress and-indicates tensile stress.
[0010]
As shown in FIG. 15 (a), when prestress is introduced into the beam 100 by the PC steel material 101, the total stress of the axial stress shown in FIG. 15 (b) and the bending stress shown in FIG. 15 (c) (FIG. 15 (d)). )). If the weight of FIG. 14A is added to this, the stress shown in FIG.
[0011]
Further, as shown in FIG. 16 (a), when post compression is applied to the upper side of the girder by the compressed PC steel material 102, the stress diagram of this post compression becomes FIG. 16 (d), and the stress is obtained by combining with FIG. 15 (e). Is as shown in FIG.
[0012]
When a uniformly distributed load 103 as shown in FIG. 17A is applied, the resultant stress of the stress due to the load (FIG. 17B) and FIG. 16E is as shown in FIG. In the bipre girders, the tensile stress at the upper and lower edges of the girders is thus reduced, so that the girder height can be lowered.
[0013]
Another technique is a pre-beam girder that uses a bending girder of a steel girder to reduce the girder height span ratio with a pre-stressed synthetic girder (see, for example, Non-Patent Document 2).
[0014]
The pre-beam girder 110 is a rational composite girder of a steel girder 120 having a cross section and a concrete 130 as shown in FIG. The steel girder 120 is an assembly-welded I-girder with manufacturing warpage. The lower flange 121 is provided with a block gibel 124, the upper flange 123 is provided with a stud diver 125, and is combined with slab concrete 132. Prestress is introduced into the lower flange concrete 131 using the bending rigidity of the steel girder 120.
[0015]
The principle of the pre-beam beam is shown in FIGS. As shown in FIG. 7, a load P ₁ shown in FIG. 8 is loaded on a steel girder 120 having an I-shaped cross section provided with a predetermined warp, and a bending moment including a design moment is applied. In this state, the lower flange concrete 131 is placed as shown in FIG. When opening the applied load P _1, the compressive force is introduced into the lower flange concrete 131, Purebimu shown in FIG. 10 is completed. The pre-beam girder 110 is installed and a web and slab concrete 132 are placed as shown in FIG. The pre-beam girder 110 and the slab concrete 132 are combined to form a concrete girder on which the dead load Wd shown in FIG. 12 acts.
[0016]
Next, as shown in FIG. 13, a distributed load p, a concentrated load P, and the like are loaded. The pre-beam beam 110 can select a low beam height.
[0017]
[Patent Document 1]
Japanese Patent No. 3279835 Patent Gazette (page 2-4)
[Non-Patent Document 1]
“Bipre Construction Method” (Bipress Stressing Construction Association) Catalog (Page 1-5): Issued August 1997 [Non-Patent Document 2]
“PREBEAM” (published by Prebeam Promotion Association) catalog (page 4-5): 13,2000
[0018]
[Problems to be solved by the invention]
Although the steel plate web bridge has excellent characteristics as described above, a technique for lowering the girder height has not been known. In addition, the bi-pre method, which is a technique for reducing the girder height, has a disadvantage that the girder's own weight becomes heavy, and the pre-beam method has a disadvantage that it has a complicated manufacturing process.
[0019]
The present invention inherits the advantages of the steel plate web bridge as it is, makes it possible to reduce the weight of the girder and save labor, and devise it to reduce the girder height, so that the girder height span ratio is 1/30 or less. The object is to provide an I-girder bridge (steel web bridge) with a low girder height that can be held down and spans 50 m. Moreover, it aims at providing the construction method of such a steel plate web bridge.
[0020]
[Means for Solving the Problems]
The present invention has been made to solve the above-mentioned problems, and provides a steel plate web bridge characterized by taking the following technical means. That is, the present invention embeds or half-finishes a lower floor slab concrete pre-stressed by a pre-tension method, a steel plate web in which a steel material is continuously attached to the upper end in the longitudinal direction, and the steel material to which a compressive force is applied. A steel plate web bridge characterized in that an intermediate girder made of upper floor slab concrete to be embedded is provided at an intermediate portion of a span.
[0021]
Here, the steel material means flat steel, round steel, steel pipe, angle steel, channel steel, H-shape steel, deformed steel, or other long steel materials, the longitudinal direction of which is the upper end of the steel plate web, and the longitudinal direction Attach to. As will be described later, this steel material can be applied with a compressive force before placing concrete. Semi-embedding refers to a state where a part or surface of a steel material is exposed in concrete and is embedded in concrete.
[0022]
In such a steel plate web bridge, if the intermediate girder has a length of 50 to 70% of the entire span, it is convenient to lower the girder height described later. Moreover, this steel plate web bridge is effective and suitable when applied to a bridge having an effective application span of 25 to 50 m.
[0023]
Moreover, if the steel plate web of the said steel plate web bridge is made into a corrugated steel plate, it is lightweight, and it becomes easy to apply compressive force and prestress to the steel material and the concrete floor deck attached to the upper end of the web, which is preferable.
[0024]
The steel plate web bridge can be manufactured by the following construction method. That is, the method of the present invention is a method for laying a steel sheet web bridge, characterized by comprising the following steps (A) to (D).
[0025]
(A) A member for an intermediate girder composed of a concrete lower floor slab in which pre-stress is introduced by a pre-tension method and a steel plate web in which a steel material is continuously attached to the upper end in the longitudinal direction is manufactured.
[0026]
(B) Supporting both ends of the intermediate girder member, extending an extension girder composed of a concrete upper and lower floor slab and a steel plate web from both ends of the intermediate girder member, and then tensioning the upper floor slab PC steel The compression force is applied to the steel material at the upper end of the steel plate web of the intermediate girder.
[0027]
(C) The steel material of the member for intermediate girders is embedded or semi-embedded, and the upper floor slab concrete is cast, and then a tension force of about ½ of the post-tension PC steel material is introduced to the entire span.
[0028]
(D) The support position is moved to both ends of the entire span, the tension of the upper floor slab PC steel is released, the compressive force applied to the steel at the upper end of the steel plate web is released and tensile prestress is introduced into the concrete, and then the post Re-tension the tension PC steel and introduce the final tension to the entire girder.
[0029]
In the above, if the steel sheet web is a corrugated steel sheet, it is preferable because compression force is imparted and tension is easy.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention using corrugated steel sheets for steel sheet webs will be described below with reference to the drawings.
[0031]
The steel plate web bridge of the present invention is a web bridge having a low girder height using pre-tension and post-tension, with an intermediate girder interposed in the middle part of the span, extension girder connected to both ends. The intermediate girder is prestressed concrete floor slab, steel plate web with steel material attached continuously in the longitudinal direction at the upper end, and the steel plate is embedded in the lower part or semi-embedded and tensile prestress by pre-compression system is introduced It consists of a concrete upper floor slab.
[0032]
Embodiments of the present invention will be described below with reference to the drawings.
[0033]
FIG. 1 shows an embodiment of a corrugated steel web bridge 1 according to an embodiment of the present invention. The right half of the figure shows a cross section of an intermediate girder 10 and the left half of the figure shows an intermediate girder. 10 is a front view of the end of the extension beam 50 formed at both ends in the longitudinal direction of FIG.
[0034]
The intermediate girder 10 includes a lower floor slab 20, a web 30, and an upper floor slab 40. The lower floor slab 20 includes a pretension PC steel material 21 and is prestressed. The lower end of the corrugated steel web is embedded in the lower floor slab. A sheath 22 through which a post-tension PC steel material for introducing final prestress is inserted is incorporated.
[0035]
The web 30 is made of a corrugated steel plate, the lower end is embedded in the lower floor slab, and the steel material 31 is attached to the upper end in the longitudinal direction. The steel material 31 is embedded or semi-embedded in the upper floor slab concrete. Semi-embedding means being embedded in a manner in which a part of the surface is exposed. As will be described later, the steel material 31 is for introducing tensile prestress into the concrete in the upper floor slab. The kind of steel material is not ask | required.
[0036]
The upper floor slab 40 is made of concrete in which the steel material 31 is embedded or semi-embedded, and is coupled to the upper end of the corrugated steel sheet. A sheath 41 for applying prestress to the steel material 31 by post tension is provided in the upper floor slab 40. The sheath 41 is provided not only at the intermediate beam portion but over the entire span.
[0037]
The left half of FIG. 1 shows the end face of the extension girder 50, and the extension girder 50 is composed of a lower floor slab 60, a corrugated steel web 70 and an upper floor slab 80. A PC steel fixing portion 92 for introducing prestress due to final post tension is fixed to the fulcrum cross beam 91. A lower end of the corrugated steel web 70 is fixed to the lower floor slab 60 of the extension beam 50. A corrugated steel web 70 is inserted and fixed in the upper floor slab 80. In the upper floor slab 80, a sheath 41 for storing a PC steel material that applies a compressive force to the steel material 31 is provided.
[0038]
Next, the construction method of the corrugated steel web bridge according to the embodiment will be described with reference to FIGS.
[0039]
(A) Process: A member for an intermediate girder composed of a concrete lower floor slab into which prestress is introduced by a pretension method and a corrugated steel sheet web in which a steel material is continuously attached to the upper end in the longitudinal direction is manufactured.
[0040]
FIG. 2 shows a side view of a bridge body having a full span according to an embodiment of the present invention, which comprises an intermediate beam 10 and extended beams 50 extending from both ends thereof. The intermediate girder member is a member for forming the intermediate girder 10, and is a corrugated steel plate in which a concrete lower floor slab 20 in which prestress is introduced by a pretension method and a steel material 31 are continuously attached to the upper end in the longitudinal direction. This is a member that is composed of the web 30 and before placing the upper floor slab concrete. This intermediate girder member is manufactured at the factory. Since this intermediate girder member has a steel material such as channel steel attached to the upper end of the corrugated steel plate, it has high rigidity and is easy to carry.
[0041]
(B) Process: The both ends of the said member for intermediate girders are supported, and the extension girder which consists of a concrete upper and lower floor slab and a corrugated steel sheet web is extended and constructed from the both ends of the member for intermediate girders, respectively.
[0042]
As shown in FIG. 3, in the main girder production yard 12 at the installation point, both ends of the intermediate girder member are supported by the fulcrum 11, and the extension girder 50 is constructed on the ground 51. A temporary fulcrum 13 may be provided at the center portion of the span for reinforcement when the upper deck slab concrete is placed later. The extension beam 50 is coupled to the intermediate beam member. Next, the PC steel material of the upper floor slab is tensioned by the tension jack 52, and a compressive force is applied to the steel material 31 of the intermediate girder member by applying the assumption near the both ends of the intermediate girder member. This assumption is preferably performed by a nut (PC steel bar), a wedge (PC steel wire), welding (PC steel bar) or the like in the vicinity of the end of the steel member of the intermediate girder member.
[0043]
(C) Process: The steel material of the member for intermediate girders is embed | buried or semi-embedded, and an upper floor slab concrete is laid, and after hardening, the tension force of about 1/2 of post tension PC steel material is introduce | transduced to all the spans.
[0044]
FIG. 4 shows this process. Place concrete in the upper girder forming position of the intermediate girder member. At this time, the steel material is embedded or semi-embedded in the concrete. When the fulcrum 13 (see FIG. 3) is provided at the center of the span, this is removed after placing the upper floor slab concrete. Next, about half the tension of post-tension PC steel is introduced to all spans.
[0045]
(D) Process: A support position is moved to the both ends of all the spans, the tension | tensile_strength of upper-slab PC steel material is released, secondary tension | tensile_strength of post tension PC steel material is performed, and final tension force is introduce | transduced.
[0046]
As shown in FIG. 5, the fulcrum position is moved to both ends of the entire span. By releasing the tension of the upper floor slab PC steel material, tensile prestress is applied to the concrete by the steel material 31 attached to the upper part of the corrugated steel sheet. Finally, the final tension is introduced into the full span PC steel.
[0047]
【Example】
The present invention was applied to a road bridge having a span of 35 mm and a width of 12 m. Channel steel was used as the steel material that was attached to the upper end of the corrugated steel web and embedded in the upper deck.
[0048]
The cross section of the main girder was an I-girder having an upper floor slab width of 1100 mm, a girder height of 1150 mm, and a lower floor slab width of 950 mm.
[0049]
Under the same conditions, a road bridge with a standard section of post-tension girder has a T-girder with a main girder section of 1500 mm wide and a girder height of 2000 mm according to the design calculation.
[0050]
【The invention's effect】
Since the steel plate web bridge of the present invention is configured as described above, it is a lightweight bridge using a steel plate web, and can reduce the dead load by about 30% compared to the bi-pre method and the pre-beam method. It is also excellent in earthquake resistance, and it is possible to reduce the cost of substructure. In addition, there is an excellent effect that the digit height span ratio can be suppressed to 1/30.
[0051]
The steel plate web bridge of the present invention can be easily and rationally constructed by the above-described method of the present invention, and the present invention is extremely useful and greatly contributes.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a central girder of a span and a front view of an end of a girder of an embodiment.
FIG. 2 is a construction process diagram of the example.
FIG. 3 is a construction process diagram of the example.
FIG. 4 is a construction process diagram of the example.
FIG. 5 is a construction process diagram of the example.
FIG. 6 is a diagram illustrating the principle of a pre-beam beam.
FIG. 7 is a diagram for explaining the principle of a pre-beam beam.
FIG. 8 is a diagram illustrating the principle of a pre-beam beam.
FIG. 9 is a diagram illustrating the principle of a pre-beam beam.
FIG. 10 is a diagram for explaining the principle of a pre-beam beam.
FIG. 11 is a diagram illustrating the principle of a pre-beam beam.
FIG. 12 is a diagram illustrating the principle of a pre-beam girder.
FIG. 13 is a diagram for explaining the principle of a pre-beam beam.
FIG. 14 is a diagram illustrating the principle of the bi-pre method.
FIG. 15 is an explanatory diagram of the principle of the bi-pre method.
FIG. 16 is a diagram illustrating the principle of the bi-pre method.
FIG. 17 is a diagram illustrating the principle of the bi-pre method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Corrugated steel web bridge 10 Intermediate girder 11 Support point 12 Yard 13 Temporary support point 20 Lower floor plate 21 PC steel material 22 Sheath 30 Web 31 Steel material 40 Upper floor plate 41 Sheath 50 Extension girder 51 Ground 52 Tension jack 53 PC steel material 60 Lower floor plate 70 Waveform Steel plate web 80 Upper floor slab 91 Folding cross girder 92 Fixing part 100 Girder 101 PC steel material 102 Compressed PC steel material 103 Load 110 Pre-beam girder 120 Steel girder 121 Lower flange 123 Upper flange 124 Block gibber 125 Stud diver 130 Concrete 131 Lower flange concrete 132 Slab concrete

Claims (6)

A concrete lower floor slab pre-stressed by a pre-tension method, a steel plate web in which a steel material is continuously attached to the upper end in the longitudinal direction, and a concrete upper floor slab in which the steel material provided with a compressive force is embedded or semi-embedded. A steel plate web bridge comprising an intermediate girder made of 2. The steel plate web bridge according to claim 1, wherein the intermediate beam is 50 to 70% of the entire span. The steel plate web bridge according to claim 1 or 2, wherein an effective application span is 25 to 50 m. The steel plate web bridge according to any one of claims 1 to 3, wherein the steel plate web is a corrugated steel plate. A method for laying a steel plate web bridge, characterized by comprising the following steps (A) to (D).
(A) A member for an intermediate girder composed of a concrete lower floor slab in which prestress is introduced by a pretension method and a steel plate web in which a steel material is continuously attached to the upper end in the longitudinal direction is manufactured.
(B) Supporting both ends of the member for intermediate girders, extending extension girders made of concrete upper and lower floor slabs and corrugated steel webs from both ends of the members for intermediate girders, and then tensioning the upper floor slab PC steel Then, compressive force is applied to the steel material at the upper end of the steel plate web of the intermediate girder.
(C) The steel material of the member for intermediate girders is embedded or semi-embedded, and the upper floor slab concrete is cast, and then the tension of about 1/2 of the post-tension PC steel material is introduced to the entire span.
(D) The support position is moved to both ends of the entire span, the tension of the upper floor slab PC steel is released, the compressive force applied to the steel at the upper end of the steel plate web is released and tensile prestress is introduced into the concrete, and then the post Re-tension the tension PC steel and introduce the final tension to the entire girder.   6. The method of installing a steel plate web bridge according to claim 5, wherein the steel plate web is a corrugated steel plate.

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