JP3797560B2 - Bridge segment and its construction method - Google Patents

Description

The present invention relates to a suspension-type span-by-span construction method in which a precast bridge segment manufactured at a factory or a yard is suspended from a span construction girder for every span, and relates to the construction method of the bridge segment and the bridge segment. Is.

  The precast segment method is a method of manufacturing a structure by dividing it into a bridge axis direction or a direction perpendicular to the bridge axis at a factory or production yard, carrying it to the construction site, and introducing prestress into an integrated structure. It is used for construction.

Advantages of applying the precast segment construction method to bridge construction include the following.
(1) Since the precast segment can be produced and stocked during the construction of the substructure, the production process and the erection process can be set separately, and the construction period can be greatly shortened.
(2) The production of the precast segment is a repetitive operation in a factory or production yard, and a structure with stable quality can be produced. Moreover, rationalization and labor saving are possible by performing mechanized construction.
(3) By storing the segments in the stock yard, drying shrinkage after installation and deformation due to creep are reduced.

  From the above points, the precast segment construction method can be expected to be the most rapid construction and labor-saving construction in the field of PC bridge construction, but for that purpose, in terms of segment production, simplification of the formwork structure and automation of equipment, etc. are problems. In terms of segment erection, there are issues of rationalization of segment joints by attracting steel rods before fixing the main cable tension, and overcoming these issues will be an advantageous method for large-scale bridge construction. Effectiveness can be further utilized.

  One of the typical erection methods of precast segment method is the span-by-span method. This is a construction method in which a segment of one diameter manufactured in a factory or a yard is transported on a construction girder, joined after predetermined positioning, and erected one by one while applying prestress. This method is suitable for 40 to 60m PC girder bridges.

  The span-by-span erection procedure will be described with reference to FIGS. 5A to 5E. In step 1, the peer segment 3 is installed in advance on the fulcrum 2 of the three piers 1a, 1b, 1c by a crane, and the erection girder is installed. (Girder) 4 is set between the diameters of the piers 1a and 1b (FIG. A).

  In step 2, after the installation girder 4 is set, the segments 5 carried by the trailer are lifted by one lifting device 6 by one span (FIG. B).

  In step 3, the position of the lifted segment 5 is adjusted, the adhesive is applied to the joining surface of the segment, and then the segment 5 is integrated with the drawing steel rod 7 (details are shown in FIG. 6). The joint 8 is constructed by placing the concrete in place (Fig. C).

  In step 4, after the concrete of the place joint 8 is hardened, the main cable (PC steel wire) 10 is disposed and tension is fixed, and then the drawing steel bar 7 is removed (FIG. D).

  In step 5, the construction girder 4 is moved between the piers 1b and 1c after completion of construction between the piers 1a and 1b. Steps 1 to 5 are sequentially repeated to construct the bridge girder 5a (Fig. E).

  FIGS. 6 and 7 (a) show a bridge girder 5a between one diameter, and a plurality of segments 5 are suspended by a girder (not shown) between peer segments 3 installed on a fulcrum 2. Are positioned and joined.

  As shown in FIG. 7B, the segment 5 is a box girder in which the upper floor slab 12 and the lower floor slab 13 are joined by the web 14, and the drawing projections 15 project from the inner surface of the web 14 of each segment 5. In addition, a plurality of (eight on the left and right sides in the drawing) attracting holes 16 are formed in the attracting protrusion 15, and the attracting steel rod 7 is inserted into the attracting hole 16. In general, a shear key 17 (shown in FIG. 4) is projected from the end face of the segment.

  In the span-by-span construction method, as described above, after adjusting the position of the suspended segment 5, an adhesive is applied to the end face of the segment 5 to be joined, and the attracting protrusion 15 provided on the inside of the segment 5 is attracted by steel. The tension is fixed between the adjacent segments by the fixing member 18 and the fixing device 19 installed at the end of the drawing steel bar 7 through the bar 7, and the tension is kept until the adhesive is cured. After that, concrete is placed on the joint 8 provided between the piers 3 and the segments 5 integrated with the fulcrum, and the main cable (FIG. 5d) 8 is bridged over the entire bridge girder to fix the tension. Thereafter, the tension of the pulling steel bar 7 is released and pulled out from the pulling hole 16, and the segment 5 is removed from the installation girder 4.

In the bridge by the span-by-span method, as described above, the main cable 10 for introducing prestress to the entire bridge girder is disposed through the inner space of the segment 5 (not shown in FIGS. 6 and 7). In this case, the main cable 10 is deflected to a position away from the segment segment neutral axis so that the effect of the tension of the main cable 10 is further exerted in the portion where the load is greatly applied between the spans. For this reason, a segment (referred to as a “deviator segment”) in which a deviator (deflecting member) having a cable insertion hole is provided in the lower floor slab of the segment 3 is disposed at a predetermined portion. The deviator segment is provided with an intermediate partition.
JP-A-8-134845 JP-A-6-193017

  In the span-by-span construction method, it is necessary to draw the segments closer together in order to maintain the pressure contact state of the adhesive applied to the segment end faces before the main cable is disposed. Conventionally, as the attracting means, adjacent segments are attracted one by one with a attracting steel rod, so that there are problems such as the following (1) to (4) in the complexity of segment production and troublesome construction. It was.

(1) Since the segment mold must be modified in order to provide the pulling projection in the production of the segment, the time and production cost required for it are required. (2) At the time of erection, the work is complicated because a steel rod is inserted into the pulling projection one segment at a time and the tension is fixed, and these many steel rods must be removed after the cable tension of the main installation. (3) When inserting the external cable of the main installation, the inside of the hollow segment (box girder) is narrow. (4) The drawing protrusion is not necessary after the bridge girder is completed, and it is useless to provide it in all the segments.

The present invention solves the above-mentioned problems (1) to (4) by rationalizing the drawing process between the segments using the drawing steel bar in the construction method of the bridge segment by the span-by-span construction method of the suspension method. For this purpose, in addition to improving workability by simplifying and speeding up the work, the segment structure is simplified and the ease of segment production is realized.

  In order to achieve the above object, the present invention is configured as follows.

  In the first invention, the hollow precast segment is supported by being suspended from the installation girder, and after adjusting the position of the existing segment joined to the peer segment on the pier, both segments are joined via an adhesive. Then, the pulling steel rod is inserted into the pulling projection provided in the segment to maintain the tension, and the main cable inserted through the entire length of the bridge girder for one span is fixed in tension, and then the pulling steel rod is removed. In addition, in the construction method of the bridge segment by the span-by-span construction method of removing the bridge girder from the construction girder, a plurality of attracting holes are opened in the partition wall provided in the segment, and the attracting steel bar is provided in the attracting hole The multiple segments are drawn simultaneously from the side of the already installed bridge girder by inserting the ends of the steel bars and fixing the ends of the drawn steel bars in tension. To.

  According to a second aspect of the present invention, in the first aspect of the present invention, two or more pulling holes are provided on the left and right sides of the partition wall, and the pulling steel rods extending from the previously installed side are provided. Allocate the same number of drawing holes for insertion and the drawing holes for inserting the drawing steel rods that will be extended to the next side.In one drawing hole, the bridge girder previously installed Insert the steel rod that pulls the multiple segments on the side and fix the tension at the end. Insert the steel rod that pulls the next multiple segments into the other pulling hole and fix the end at the tension. It is characterized by doing.

In a third aspect of the present invention, there is provided a bridge segment in which a deviator having a cable insertion hole and a partition wall are provided in a hollow segment, and the partition wall has an insertion hole for a attracting steel rod for attracting and joining a plurality of segments. Is characterized by the fact that there are several.

  In the present invention, a pulling hole is opened in the partition wall of the deviator segment, and a plurality of segments are joined at once by inserting and pulling a pulling steel rod into the pulling hole. Therefore, as compared with the conventional method in which the drawing projections are provided on all the segments and the adjacent segments are drawn at the time of erection, the following effects are obtained.

(1) Since the present invention does not require a drawing projection for each segment at the stage of production as in the prior art, the segment formwork can be greatly simplified, greatly contributing to the reduction of production costs.

(2) At the time of erection, the steel bar is inserted into the opening of the opening of the deviator segment installed at intervals of several, and the tension is fixed. Compared with the work of inserting and fixing a large number of attracting steel bars to the protrusions, the amount of work is greatly reduced.

(3) In the case of the conventional construction method, when the main cable is inserted, the inside of the box girder is very narrow and there are many end portions of the drawn steel bar, which is very dangerous. The difficulties and dangers are also eliminated.

(4) As described above, according to the present invention, after the bridge girder is completed, the originally unnecessary and unnecessary attracting protrusions are eliminated from the segment, and the conventional attracting protrusions are also used as the partition walls of the deviator segment. In addition to simplifying and speeding up the construction work, it is possible to simplify the bridge segment structure, facilitate manufacturing, and reduce costs.

  Next, the present invention will be described in detail based on the illustrated embodiment.

  1 is a schematic side view of a bridge constructed by a span-by-span construction method according to the present invention, FIG. 2 is an enlarged partial view of FIG. 1, and FIG. 3A is a cross-sectional view of a deviator segment according to the present invention, (B) is sectional drawing of the center part of FIG. (A), FIG. 4 is the fracture | rupture perspective view of a deviator segment. In the figure, common elements and conventional elements will be described with common reference numerals.

  In FIG. 1, a plurality of precast segments 20 are suspended by a standing girder (not shown) between peer segments 3 installed on a fulcrum 2 in one span of a PC girder bridge having a span of 40 to 60 m. After being done, the state of being joined by the drawing steel bar 21 is shown. The segments 20 installed between one diameter are manufactured at a factory or a yard, and then sequentially lifted by a lifting device, transferred to a erection girder, suspended, and positioned at a predetermined position. The process so far is the same as the conventional process.

  In the present invention, attention is paid to the fact that, among the plurality of segments 20 installed between one diameter, the devator segment 20a for guiding the main cable (outer cable) is installed at a predetermined interval. By improving the segment 20a, the pulling segment that is tensioned by the pulling steel rod 21 is also used, and the joining process and the joining structure have the features of the present invention.

  3 and 4 show examples of the structure of the deviator segment 20 a, which is composed of a box girder in which an upper floor slab 12 and a lower floor slab 13 are connected by a web 14. The deviator segment 20a includes a deviator (deflection member) 23 having a main cable insertion hole 22 on the upper surface of the lower floor slab 13 and an intermediate partition wall 24. The intermediate partition wall 24 has a certain thickness and strength, the lower end is provided integrally with the deviator 22, the upper end is provided integrally with the lower surface of the upper floor slab 12, and one side surface is provided integrally with the web 14. . The intermediate partition wall 24 reinforces the strength of the segment and may pass through a main cable that is deflected to the intermediate partition wall 24.

  In the present invention, four attracting holes 26 are formed on the left and right sides of the intermediate partition wall 24 in the direction of the bridge axis, and the attracting steel rod 21 is inserted into each attracting hole 26 to fix the end portion in tension. Of the plurality of drawing holes 26, the first and third holes from the top are the drawing holes 26a for inserting the drawing steel rod extending from the previously installed segment side, and the second from the top. The fourth hole is a pulling hole 26b for inserting a pulling steel rod extending to the segment side to be newly provided, and the same number of holes are allocated.

  More specifically, in FIGS. 1 and 2, the deviator segments 20a are arranged adjacent to each other in the central portion of the span, and are arranged on both sides via the normal segments 20b. Further, it is provided between the peer segment 3 on the fulcrum 2 via two ordinary segments 20b.

  In the above, the steel rod 21 that draws the plurality of segments 20 from the bridge girder side (that is, the peer segment 3 side) already installed in one of the drawing holes 26a is inserted, and the end portion is tensioned to fix the fixing member 27. To fix. Subsequently, the steel rod 21 that draws the next plurality of segments 20 (center side of the span) is inserted into the other drawing hole 26b, and the end portion is tensioned and fixed by the fixing member 27. This drawing operation is repeated while an adhesive is applied to the joining end face of the segment 20, and an appropriate compressive stress is continuously applied. In FIG. 1, steel brackets 28 are provided at both end segments in the vicinity of the fulcrum 2, and the ends of the attracting steel rod 21 extending from the center of the span are fixed to the steel bracket 28 by a fixing device 29. The

  After that, concrete is placed on the joint provided between the segments 20 integrated with the peer segment 3 on the fulcrum 2, and after waiting for hardening, the concrete is installed inside the hollow segment 20 arranged over the entire bridge girder. Insert the outer cable (not shown) and fix the end. Thereafter, the tension of the attracting steel bar 21 is released and the steel bar 21 is pulled out from the attracting hole 26 of the intermediate partition wall 24 and removed. Thereafter, the segment 20 is removed from the erection girder.

  In the embodiment, the ordinary segments 20b other than the deviator segment 20a do not need to have a drawing protrusion on the hollow inner surface. Therefore, the segment production form may be a simple formwork apparatus in which a flat steel formwork is provided in the three directions of the side surface and the upper surface, and the upper surface of the lower floor slab has no formwork. It will be very easy. Since the attracting steel rod 21 is disposed using the deviance segment 20a, the number of temporary tensions is reduced. Further, there is an advantage that the inside of the box after joining is neat and the efficiency and safety of the subsequent work are excellent. Since several segments are tensed together, it takes some time from applying the adhesive to fixing the temporary tension, and there is a concern about the hardening of the first applied adhesive, but this point increases the pot life in the preparation of the adhesive Can be solved.

In addition, the intermediate partition 24 may be provided not only in the deviator segment but also in the normal segment. In some cases, the deviator segment is not provided with a partition wall, and any segment can be used if the intermediate partition wall 24 is provided. Furthermore, the present invention includes a case where the configuration described in the embodiment is modified and implemented.

It is a side surface schematic diagram of the bridge constructed by the span by span construction method concerning the present invention. It is the elements on larger scale of FIG. (A) is center part sectional drawing of the deviator segment which concerns on this invention, (b) is center part sectional drawing of a figure (a). It is a fracture perspective view of a deviator segment. (A), (b), (c), (d) is side explanatory drawing of the construction procedure which constructs a bridge segment using the conventional span-by-span construction method. It is a side surface schematic diagram of the bridge constructed by the conventional span by span construction method. (A) is an enlarged partial view of FIG. 6, (b) is a front view of a bridge segment.

Explanation of symbols

1a pier 1b pier 1c pier 2 fulcrum
3 Peer segment 4 Construction girder
5 Segment 5a Bridge girder 6 Lifting device 7 Pulling steel bar 8 Location joint 10 Main cable
12 Upper floor slab 13 Lower floor slab 14 Web 15 Pulling projection 16 Pulling hole 17 Shear key 18 Fixing member 20 Segment 20a Deviator segment 20b Normal segment 21 Pulling steel rod 22 Main cable insertion hole 23 Deviator 24 Intermediate partition 26 Pulling Hole 27 Fixing member 28 Steel bracket 29 Fixing device

Claims (3)

  The hollow precast segment is supported by suspending it from the installation girder, and after adjusting the position of the existing segment joined to the peer segment on the pier, both segments are joined via an adhesive, The drawing steel bar is inserted into the provided drawing protrusion to maintain the tension, and the main cable inserted through the entire length of the bridge girder for one span is fixed in tension, and then the drawing steel bar is removed and the installation girder In the construction method of the bridge segment by the suspension type span-by-span construction method that removes the bridge girder from the center, a plurality of drawing holes are opened in the partition wall provided in the segment, and the end of the drawing steel bar is inserted into the drawing hole In addition, a plurality of segments are drawn simultaneously from the side of the already installed bridge girder by fixing the end of the drawn steel bar in tension. Erection method of placement.   Two or more drawing holes are provided on the left and right sides of the partition wall, and the drawing holes for inserting a drawing steel rod extending from the previously installed side, Allocate the same number of pulling steel rods that extend to the newly installed side to the pulling holes, and in one pulling hole, the steel that draws multiple segments on the side of the bridge girder previously installed 2. The rod end is inserted and the end portion is tension-fixed, and the other pulling hole is inserted with a steel rod that draws the next plurality of segments, and the end portion is tension-fixed. Construction method for bridge segments.   In the bridge segment in which a deviator having a cable insertion hole and a partition wall are provided inside the hollow segment, the partition wall is provided with a plurality of insertion holes for a drawing steel rod for attracting and joining a plurality of segments. A bridge segment characterized by

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