Hollow form for precast segment girder and manufacturing method of precast segment girder

Abstract

To provide a hollow form for a precast segment girder and a manufacturing method of the precast segment girder, which can efficiently manufacture a cross section reverse U-shaped precast segment girder capable of easily recognizing aging degradation by visual inspection, a static image, a moving image or the like.SOLUTION: A hollow form 100 for a precast segment girder is for forming a hollow part (21) of a cross section reverse U-shaped precast segment girder (2) where an opening groove (22) is formed by opening a lower part of the hollow part (21) like a groove. The hollow form 100 is partitioned into multiple narrower width pieces than the width of the opening groove (22), and is constituted to be able to remove a form by extracting each piece among the multiple pieces of the hollow form 100 from the opening groove (22) after concrete placing.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a hollow formwork for precast segmental girders, which is used to form the hollow portion of a precast segmental girder with an inverted U-shaped cross section, in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, and a method for manufacturing a precast segmental girder using the same. [Background technology]

[0002] Traditionally, bridges have been known that have hollow deck girders without beams, in which hollow materials like drums, which are much lighter than concrete, are embedded to reduce weight. Hollow girders are also known, in which prestress is applied with tendons using pretensioning or posttensioning methods, and hollow girders with rectangular cross sections are embedded in the center to reduce weight, such as polystyrene foam. Other well-known bridges include T-girder bridges, which have a T-shaped cross section, and box girder bridges, which do not use the hollow materials used in large bridges, but instead have large cavities inside the bridge to reduce weight.

[0003] Furthermore, this construction method, in which precast members (segments) of various cross-sectional shapes that have been manufactured in advance in a factory or on-site yard are joined at the bridge site and prestressed to form a single unit, is called the precast segment method.In particular, among the precast segment girder bridges constructed using the precast segment method, hollow girders with rectangular cross sections have excellent cross-sectional performance relative to their weight, and are increasingly being adopted for medium-sized bridges due to their good cost performance.

[0004] For example, Patent Document 1 discloses a pretensioned hollow girder bridge in which pretensioned hollow girders prestressed by a pretensioning method are integrated with transversely fastened PC steel (see paragraphs

[0019] to

[0027] of the specification of Patent Document 1, and Figures 3 and 4 of the drawings). However, the pretensioned hollow girder described in Patent Document 1 requires the installation of relatively expensive supports between each of the multiple hollow girders and the bridge piers, which poses a problem of high support installation costs.

[0005] In order to solve these problems, Patent Document 2 discloses a bridge in which a precast cross girder 1 is provided on a substructure 4 so as to extend perpendicular to the bridge axis via a single bearing device 5 when viewed perpendicular to the bridge axis, the precast cross girder 1 is provided with a vertical girder support flange 6 that continues in the direction perpendicular to the bridge axis and protrudes in the direction of the bridge axis, and a plurality of precast vertical girders 2 are erected in parallel on the vertical girder support flanges 6 of the precast cross girder 1, and the precast cross girder 1 and the end portions of each precast vertical girder 2 are integrated (see claim 1 in the scope of claims of Patent Document 2, paragraphs

[0018] to

[0028] in the specification, Figure 2 in the drawings, etc.).

[0006] However, the pre-tensioned hollow girder with a U-shaped cross section described in Patent Document 1 and the pre-tensioned hollow girder with a U-shaped cross section, which is a pre-cast vertical girder, had the problem that the hollow parts could not be easily inspected after the bridge was completed, making it difficult to detect deterioration over time.

[0007] Therefore, the applicants of the present application have developed a precast segment girder with an inverted U-shaped cross section and an open bottom surface of the hollow cross section, which allows easy confirmation of deterioration over time through visual inspection, still images, video, etc. However, a precast segment girder with an inverted U-shaped cross section requires a folded portion at the bottom of the hollow section for strength, and it is difficult to successfully remove the formwork for the hollow section of the precast segment girder, resulting in low yield and poor manufacturing efficiency. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-169731 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-256873 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, the present invention was devised in consideration of the above-mentioned problems, and its purpose is to provide a hollow formwork for precast segmental girders and a method for manufacturing precast segmental girders that can efficiently manufacture precast segmental girders with an inverted U-shaped cross section, whose deterioration over time can be easily confirmed visually, through still images, videos, etc. [Means for solving the problem]

[0010] The first invention is a hollow formwork for a precast segment girder, which is used to form the hollow portion of a precast segment girder with an inverted U-shaped cross section, in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, and which is characterized in that the hollow formwork is divided into multiple pieces with a width narrower than the width of the open groove, and is configured so that after concrete is poured, each of the multiple pieces of the hollow formwork can be removed from the open groove and demolded.

[0011] A second invention is characterized in that, in the first invention, each divided piece of the hollow form is separated from the others by being covered with a resin film at least at the contacting portions.

[0012] The third invention is characterized in that, in the first invention, at least the outer pieces of the divided pieces of the hollow formwork that are away from the opening groove are wound with a strip-shaped tape material.

[0013] The fourth invention is characterized in that, in the first invention, the hollow formwork has a partition plate interposed along the center of the opening groove, and the partition plate is configured to be mechanically fixed to a support body with a bolt.

[0014] The fifth invention is characterized in that, in the first invention, the hollow formwork is fixed so that it does not float up when concrete is poured using a hollow formwork holding jig having a holding bolt to prevent it from floating up when concrete is poured.

[0015] The sixth invention is characterized in that, in the first invention, the longitudinal ends of the hollow formwork are fixed with hollow formwork movement prevention jigs to prevent horizontal displacement when pouring concrete.

[0016] The seventh invention is a method for manufacturing a precast segment girder using the hollow formwork for precast segment girder of the first invention to manufacture a precast segment girder with an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, characterized in that after concrete is poured, each piece of the hollow formwork is sequentially removed from the open groove and demolded.

[0017] The eighth invention is a method for manufacturing a precast segment girder in the seventh invention, which uses the hollow formwork for precast segment girder of the third invention to manufacture a precast segment girder with an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, and is characterized in that after concrete is poured, the outer piece of the hollow formwork is removed from the open groove by pulling the tape member.

[0018] The ninth invention is a method for manufacturing a precast segment girder in the seventh invention, which uses the hollow formwork for precast segment girder of the fourth invention to manufacture a precast segment girder with an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, and is characterized in that the partition plate is bolted to the support and concrete is poured.

[0019] The 10th invention is a method for manufacturing a precast segment girder in which, in the 7th invention, a hollow formwork for precast segment girder of the 5th invention is used to manufacture a precast segment girder with an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, and is characterized in that the hollow formwork is fixed with the hollow formwork holding jig to prevent it from floating up and concrete is poured.

[0020] The 11th invention is a method for manufacturing a precast segment girder using the hollow formwork for precast segment girder of the 6th invention in the 7th invention, which produces a precast segment girder with an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, and is characterized in that the hollow formwork movement prevention jig is used to fix each piece of the hollow formwork so that it does not shift horizontally relative to each other, and concrete is poured. [Effects of the Invention]

[0021] According to the first to eleventh inventions, it is possible to efficiently manufacture precast segment girders with an inverted U-shaped cross section, which allow easy confirmation of deterioration over time through visual inspection, still images, video images, etc.

[0022] In particular, according to the second invention, the divided pieces of the hollow formwork are separated from each other by covering the contacting portions with a resin film, so that when each piece of the hollow formwork is pulled out, the frictional force acting between adjacent pieces is reduced, and the hollow formwork can be easily removed from the open groove and demolded in a short time.

[0023] In particular, according to the third and eighth aspects of the invention, the outer piece that is separated from the opening groove and is difficult to remove can be easily pulled out of the opening groove simply by pulling the tape member.

[0024] In particular, according to the fourth and ninth inventions, each piece of the hollow formwork divided by partition plates can be firmly fixed without bias, preventing the pieces of the hollow formwork from shifting when concrete is poured and improving the yield of precast segment girders.

[0025] In particular, according to the fifth and tenth inventions, it is possible to prevent each piece of the hollow formwork from floating up and shifting due to buoyancy when pouring concrete, thereby improving the yield of precast segment girders.

[0026] In particular, according to the 6th and 11th inventions, it is possible to prevent each piece of the hollow formwork from shifting horizontally relative to each other when pouring concrete, thereby improving the yield of precast segment girders. [Brief explanation of the drawings]

[0027] [Figure 1] Figure 1 is a cross-sectional view showing the superstructure of a deck girder bridge consisting of multiple precast segment girders manufactured by a precast segment girder manufacturing method according to an embodiment of the present invention, cut along a vertical plane perpendicular to the bridge axis. [Figure 2] Figure 2 is an elevation view of the superstructure viewed horizontally along a direction perpendicular to the bridge axis. [Figure 3] FIG. 3 is a plan view of the superstructure of the same as seen vertically along the up-down direction. [Figure 4] Figure 4 is a cross-sectional view showing a single precast segment girder of the superstructure cut along a vertical plane perpendicular to the bridge axis. [Figure 5] FIG. 5 is a perspective view showing the cross beams of the superstructure of the same, where (a) shows the cross beam installed on the abutment, which is the substructure, and (b) shows the cross beam installed on the pier. [Figure 6] FIG. 6 is a front view showing the overall configuration of the hollow formwork according to the embodiment of the present invention, viewed along the longitudinal direction (axial direction) of the precast segment girder. [Figure 7] FIG. 7 is a right side view showing the overall configuration of the hollow formwork. [Figure 8] FIG. 8 is a front view showing the hollow form body of the hollow form in an assembled state. [Figure 9] FIG. 9 shows a partition steel plate of the hollow formwork, (a) being a front view and (b) being a side view. [Figure 10] FIG. 10 is a schematic diagram showing the area of ​​each piece of the hollow form body covered with the resin film. [Figure 11]Figure 11 shows the hollow formwork clamping jig for the hollow formwork of the same construction, where (a) is a front view seen along the longitudinal direction of the precast segment girder, and (b) is a plan view showing only the jig body before bolts are installed. [Figure 12] Figure 12 shows the hollow formwork movement prevention jig for the hollow formwork of the same, where (a) is a front view seen along the longitudinal direction of the precast segment girder, and (b) is a plan view showing only the jig body before bolts are installed. [Figure 13] Figure 13 shows the bottom frame of the hollow formwork, where (a) is a vertical cross-sectional view perpendicular to the longitudinal direction, (b) is a side view viewed horizontally, and (c) is a bottom view. [Figure 14] FIG. 14 shows the restraint band of the hollow formwork, where (a) is a front view seen along the longitudinal direction (axial direction) of the precast segment girder, and (b) is a side view. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, one embodiment of a method for manufacturing a precast segment girder according to the present invention will be described in detail with reference to the drawings.

[0029] [Precast segmental girder] 1 to 5, a precast segmental girder with an inverted U-shaped cross section manufactured by a manufacturing method for a precast segmental girder according to an embodiment of the present invention will be described. Note that the precast segmental girder according to an embodiment of the present invention will be described by taking as an example a precast segmental girder installed in a superstructure 1 of a bridge 10 that spans a two-span substructure 11 consisting of an abutment 11a and a pier 11b of a bridge 10 made of a deck girder via a bearing device 12.

[0030] Fig. 1 is a cross-sectional view showing a superstructure 1 of a deck girder bridge consisting of a plurality of precast segment girders manufactured by a manufacturing method for precast segment girders according to an embodiment of the present invention, cut along a vertical plane perpendicular to the bridge axis. Fig. 2 is an elevation view of the superstructure 1 viewed horizontally along the direction perpendicular to the bridge axis. Fig. 3 is a plan view of the superstructure 1 viewed vertically along the up-down direction. Note that the X direction in the figure is the bridge axis direction X, which is a horizontal first direction, and the Y direction is the bridge axis direction Y, which is a horizontal second direction perpendicular to the X direction. The Z direction indicates the up-down direction Z.

[0031] As shown in Figures 1 to 3, the illustrated bridge superstructure 1 (hereinafter also simply referred to as the superstructure 1) includes a deck girder 3 formed by integrating a plurality of precast segment girders 2, 2 that are manufactured with their longitudinal direction in the bridge axis direction X, which is a horizontal first direction. These precast segment girders 2 are placed on abutments 11a and piers 11b, which are the substructure 11, via a plurality of precast cross beams 4. This allows for a significant reduction in the number of relatively expensive bearings 12 that were previously required for each precast segment girder 2, thereby reducing the cost of installing the bearings 12.

[0032] (Deck girder) Next, the deck girder 3 and the precast segment girder 2 with an inverted U-shaped cross section will be described using Figures 1 to 4. Figure 4 is a cross-sectional view showing a single precast segment girder 2 of the superstructure 1 cut by a vertical plane along the direction Y perpendicular to the bridge axis. As shown in Figures 1 to 3, the deck girder 3 is made by pouring concrete into the gaps 7 between the precast segment girders 2 and hardening it. As shown in Figure 1, multiple precast segment girders 2 of a specific shape are integrated by prestressing them in the direction Y perpendicular to the bridge axis using the post-tensioning method with PC steel 13 as tendons. However, it is also possible to apply prestress in the direction X perpendicular to the bridge axis using the post-tensioning method depending on the situation.

[0033] (Precast segmental girder) As shown in Figure 4, this precast segment girder 2 is mainly formed from a girder body 20 with the same rectangular cross-sectional shape as a normal pretensioned hollow girder. This allows the use of conventional formwork, preventing cost increases. However, conventional hollow girders have the problem that it is not possible to visually inspect the interior of the hollow part with a pentagonal cross-section for rust or cracks.

[0034] Therefore, as shown in Figure 4, the girder body 20 of the precast segment girder 2 according to this embodiment has an open groove 22 of a predetermined width (D1 = 120 mm in the illustrated embodiment) that communicates with the outside in the hollow portion 21, which has a pentagonal cross section of a normal pretensioned hollow girder, and the underside of the girder body 20, which has a rectangular cross section, is open, giving it an inverted U-shaped cross section. For this reason, the deterioration over time inside the hollow portion 21 of the girder body 20 can be easily confirmed by visual inspection or by taking still or video images using a drone or the like.

[0035] As shown in Figure 4, the precast segment girder 2 is a pretensioned precast (PCPCa) girder in which multiple PC steel members 23 are inserted into the girder body 20 and prestressed using the pretensioning method, similar to conventional pretensioned hollow girders. Of course, if the span of the girder is short, prestressing using the pretensioning method is not necessary. Furthermore, precasting is not limited to manufacturing in which concrete is poured in advance in a factory, etc., but also includes manufacturing in which concrete is poured in advance in a separate yard nearby, either manned or unmanned, using a 3D printer, etc.

[0036] As shown in Figure 4, the multiple prestressing tendons 23 of the girder body 20 are surrounded by stirrup bars 24 made of steel such as D10, ensuring bending rigidity. The spacing between the prestressing tendons 23 is the same as that of conventional pretensioned hollow girders so as not to change the dimensions of the tensioning abutments. This allows existing facilities to be utilized, further reducing manufacturing costs.

[0037] Furthermore, as mentioned above, the underside of the girder body 20 has an opening groove 22, making it easy to visually confirm the ceiling surface 21a of the hollow section 21. However, the haunch upper surface 21b of the hollow section 21 shown in Figure 4 has a 45-degree inclination angle of D2 = 140 mm × D2 = 140 mm. This angle makes it difficult to see the haunch upper surface 21b from the line of sight indicated by the dashed arrow, given the width D1 of the opening groove 22 alone. For this reason, in the precast segment girder 2 according to this embodiment, the inner corner 25 facing the open underside of the inverted U-shaped cross section is chamfered linearly in accordance with the inclination angle of the haunch. Of course, this corner 25 is not limited to being chamfered linearly; it may also be chamfered curvedly. In either case, the width D1 of the opening groove 22 is reduced to ensure a predetermined strength, while improving the visibility of the haunch upper surface 21b of the hollow section 21.

[0038] (Horizontal beam) Next, the cross beam 4 will be described with reference to Figures 1 to 3 and 5. Figure 5 is a perspective view showing the cross beam 4 of the superstructure 1, where (a) shows the cross beam 4 installed on the abutment, which is the substructure, and (b) shows the cross beam 4' installed on the pier. The cross beam 4 according to this embodiment is a precast concrete member installed on each substructure 11 of the bridge, such as the abutment 11a and the pier 11b. As shown in Figure 5(a), there are two types of cross beams: a cross beam 4 installed on the abutment 11a and having an L-shaped cross section in a vertical cross section perpendicular to the longitudinal direction, and a cross beam 4' installed on the pier 11b and having a convex cross section in a vertical cross section perpendicular to the longitudinal direction.

[0039] As shown in Figure 5(a), this cross beam 4 has a beam body 40 with a vertical cross section that is elongated and rectangular, and a flange 41 that supports the longitudinal end portion that protrudes from the beam body 40 to one side in the bridge axis direction X. The beam depth (beam height) of this beam body 40 is set so that when the precast segment girder 2 is placed on the flange 41, the top surface of the beam body 40 and the top surface of the precast segment girder 2 are at approximately the same height (see Figure 2).

[0040] 5(b), the cross beam 4' includes a beam main body 40' having a rectangular vertical cross section that is long in height, and flanges 41', 42' that support the longitudinal ends of the precast segment girder 2 that protrude from the beam main body 40' in both directions along the bridge axis X. The beam depth (height) of the beam main body 40' is set so that the top surface of the beam main body 40' is lower than the top surface of the precast segment girder 2, so that there is space to pour concrete to integrate the precast segment girders 2, 2 when the precast segment girders 2, 2 are placed on the flanges 41', 42' (see FIG. 2).

[0041] Although the cross beams in this embodiment are described as being made of precast concrete, they may also be made of ordinary cast-in-place reinforced concrete. Although cast-in-place construction takes a little longer than precast cross beams, it is clear that by installing the main girders on the piers via the cross beams, the number of bearing devices 12 required for each main girder can be reduced.

[0042] (Gap material) When bridging the precast segmental girder 2 between the flanges 41 (flanges 41', 42') of the cross beam 4 (4'), it is preferable to lay a gap filler (not shown) on the flanges 41 (flanges 41', 42') before placing the longitudinal ends of the precast segmental girder 2 on the flanges 41 (flanges 41', 42'). By doing so, even if the upper surface of the flange 41 (flanges 41', 42') or the lower surface of the precast segmental girder 2 is warped or uneven, the gap between the cross beam 4 (4') and the precast segmental girder 2 can be filled, and stress acting on the superstructure 1, such as a live load, can be evenly transmitted to the substructure 11. This improves the durability of the superstructure 1.

[0043] As the gap filler, pressure-sensitive hardening rubber, non-shrink mortar such as a self-leveling material, etc. are preferred because they can fill gaps reliably without much effort. Also, the gap filler may be a resin such as a polymeric material, or a composite or laminate of two or more of pressure-sensitive hardening rubber, non-shrink mortar, and resin.

[0044] (Deck and railing) As shown in Figure 1, a flat deck 5 is formed on top of a deck girder 3 made up of multiple precast segment girders 2, and a wall parapet 6 is provided along the edge of the deck 5, which is the end in the direction Y perpendicular to the bridge axis. However, the deck 5 and parapet 6 shown in Figure 1 are made of ordinary cast-in-place reinforced concrete, and a detailed description thereof will be omitted.

[0045] (filler section) As shown in Figures 1, 3, etc., the space (gap) along the bridge axis direction X between adjacent precast segment girders 2 in the direction Y perpendicular to the bridge axis and other precast segment girders 2 is the interfacial area 7. Concrete is poured into this interfacial area 7 on-site, and the poured concrete hardens to form interfacial concrete, thereby integrating multiple precast segment girders 2 adjacent in the direction Y perpendicular to the bridge axis.

[0046] Although the above description has been given with an example of pouring filler concrete into the filler portion 7, not only concrete but also substances that harden through hydration reactions, such as mortar and gypsum, can be used for the filler portion 7, as long as it is a filler made of a time-hardening substance that is filled and hardens over time to withstand the compressive force acting on the filler portion 7. In particular, when the width of the filler portion 7 is narrow, it is preferable to use a time-hardening substance, such as adhesive resin, which has a shorter curing period (time until hardening) than concrete, because this shortens the curing period and construction period.

[0047] (bulkhead) 2 and 3, the multiple precast segment girders 2 arranged side by side in the direction Y perpendicular to the bridge axis are integrated at predetermined intervals by partition walls 8 made of cast-in-place reinforced concrete that resist horizontal forces. In other words, the portion of the precast segment girder 2 where the bottom surface of the hollow cross section is open and has an inverted U-shaped cross section is part of the length of the girder; in other words, part of the length of the precast segment girder 2 where the inverted U-shaped cross section is closed off has a rectangular cross section.

[0048] Specifically, except for the outer girder 2' located on the outermost side, the general precast segment girders 2, which are the middle girders located on the inside, are provided with bulkheads 8 at predetermined intervals calculated by structural calculations in the bridge axis direction X. The outer girder 2' located on the outermost side has bulkheads 8 at shorter intervals.

[0049] In the illustrated embodiment, the outermost outer girder 2' has two or more bulkheads 8 provided at predetermined intervals. This is because the outer girder 2' is more directly subjected to lateral loads such as wind loads and collision loads than the general precast segment girder 2, which is the middle girder. By providing bulkheads 8 in this way, it is possible to withstand lateral loads such as wind loads and collision loads even when the girder body 20, which has a rectangular cross-section and is weaker in strength than conventional hollow girders, has an open inverted U-shaped cross-section at the bottom.

[0050] (joint concrete) 2 and 3, the precast segment girders 2 on the piers 11b are connected in the bridge axis direction X with predetermined reinforcement and then poured with joint concrete 9. Like the interfacial concrete of the interfacial filler 7, this joint concrete 9 can also be a filler made of a time-hardening substance other than concrete.

[0051] According to the superstructure 1 of the bridge 10 equipped with the deck girder 3, which is a precast segment girder according to the embodiment described above, unlike conventional hollow girders, an open groove 22 that communicates with the outside is formed in the hollow portion 21, and the underside of the girder body 20, which has a rectangular cross-sectional outer shape, has an open inverted U-shaped cross-section, so that the presence or absence of rust or cracks inside the hollow portion can be inspected visually, etc., and deterioration over time can be easily confirmed by visual inspection, still images, video, etc.

[0052] In addition, the corners 25 of the precast segment girder 2 of the superstructure 1 are chamfered, making it easier to observe the inside of the hollow portion 21 of the precast segment girder 2 visually, using still images, or video, making it easier to detect deterioration over time and facilitating repairs, etc.

[0053] Furthermore, according to the superstructure 1, the precast segment girders 2 of the deck girder 3 are integrated together by applying prestress using the post-tensioning method, thereby making the bridge 10 stronger and more durable.

[0054] In addition, since the superstructure 1 can install bearing devices 12 via cross beams 4 (4') between the substructure 11 and the precast segment girder 2 of the superstructure 1, the number of expensive bearing devices 12 required for each girder can be reduced, and the construction costs of the bridge superstructure 1 can be reduced.

[0055] In addition, according to the superstructure 1, the precast segment girders 2 of the general section located on the inside are provided with bulkheads 8 at predetermined intervals in the bridge axis direction X, and the outer girders 2' located on the outermost sides are provided with bulkheads 8 at shorter intervals, so even if open grooves 22 are formed on the underside of the precast segment girders 2, they can withstand horizontal forces acting as external forces such as earthquakes, wind forces, wave forces, and collision loads.

[0056] Furthermore, rather than providing an open groove 22 along the entire length of the precast segment girder 2 of the superstructure 1, a portion of the girder's length is blocked off and an open groove 22 is provided only along a portion of the length, thereby making it possible to withstand horizontal forces acting as external forces in the same way as the bulkhead 8, without having to cast the bulkhead 8 in place.

[0057] [Hollow formwork for precast segmental girders] Next, using Figures 6 to 14, a hollow formwork 100 for a precast segmental girder and its accessories for forming the hollow portion 22 of the precast segmental girder 2 used in a manufacturing method of a precast segmental girder according to an embodiment of the present invention will be described in detail. Figure 6 is a front view of the overall configuration of the hollow formwork 100 according to an embodiment of the present invention, viewed along the longitudinal direction (axial direction) of the precast segmental girder 2 to be manufactured, and Figure 7 is a right side view showing the overall configuration of the hollow formwork 100. The formwork that forms the outside of the precast segmental girder 2 is the same as the formwork for a conventional pretensioned hollow girder, and is not shown or described here.

[0058] As shown in Figures 6 and 7, the hollow formwork 100 is composed of a hollow formwork main body 101 divided into multiple pieces, a hollow formwork holding jig 110 that holds the hollow formwork main body 101 to prevent it from floating up, a hollow formwork movement prevention jig 120 that prevents the hollow formwork main body 101 from moving horizontally, a bottom frame 130 for forming the opening groove 22 of the precast segment girder 2 mentioned above, and a restraint band 140 that holds the multiple divided hollow formwork main body 101 together.

[0059] (Hollow formwork body) Figure 8 is a front view showing the assembled hollow formwork main body 101. As shown in Figure 8, the hollow formwork main body 101 is a formwork for forming a hollow section 22 that is symmetrical on the left and right sides with a central partition steel plate 102 as a partition plate, and is made up of multiple divided pieces: from left to right, left piece 103, left center piece 104, central left piece 105, central right piece 106, right center piece 107, and right piece 108.

[0060] 9 shows the partition steel plate 102, with (a) being a front view and (b) being a side view. The partition steel plate 102 is a steel plate that divides the entire length of the precast segment girder 2 into two, and the pair of partition steel plates 102 shown in FIG. 9 has the function of dividing the hollow formwork main body 101 into left and right halves. However, the partition plate according to the present invention is not limited to a steel plate, and may be any member having a predetermined strength and rigidity that can separate the pieces of the hollow formwork 100 so that they do not shift when concrete is poured.

[0061] 9, this partition steel plate 102 is composed of a rectangular (rectangular) steel plate body 102a with a length L1 of 988 mm, a height H1 of 440 mm, and a thickness of 3.2 mm, and two tab pieces 102b protruding 60 mm from the lower end of the steel plate body 102a. Each of these tab pieces 102b has a bolt hole 102c with a diameter of 18 mm drilled therein.

[0062] Furthermore, the left piece 103, left-center piece 104, center-left piece 105, center-right piece 106, right-center piece 107, and right piece 108 are each made of foamed resin, and as shown in Figure 10, are covered with a resin film F1 such as polypropylene resin and have cut edges to make them easy to remove. Figure 10 is a schematic diagram showing the area of ​​each piece of the hollow form body 101 that is covered with the resin film F1.

[0063] As shown in FIG. 10 , the hollow form body 101 according to this embodiment has a left piece 103, a left center piece 104, a right center piece 107, and a right piece 108, which are located on the outside and difficult to remove, completely covered with a resin film F1. The central left piece 105 and the central right piece 106, which are easily removed, are covered only within 100 mm of their top and bottom ends. Furthermore, it is preferable that the foamed resin and the resin film F1 be attached to each other with an adhesive or the like to prevent misalignment. This is because this reduces the risk of tearing the protective resin film F1 when it is removed, allowing for easy and quick removal. However, the foamed resin and the resin film F1 do not necessarily have to be bonded together. This is because if the resin film F1 has an appropriate thickness, it reduces the risk of tearing the resin film F1 when it is removed, thereby eliminating the need for bonding.

[0064] Furthermore, the hollow form body 101 may be configured such that only one of the left and right pieces, for example, the left piece 103, the left-center piece 104, or the center-left piece 105, is covered with the resin film F1. This is because removing one of the left and right pieces of the hollow form body 101 creates a space that allows workers to easily reach in and remove the remaining pieces.

[0065] Furthermore, in the hollow form body 101 according to this embodiment, each piece is preferably covered with a resin film F1 and then wrapped around the resin film F1 at 300 mm intervals with a tape member such as a strip-shaped filament tape (not shown) having a width of 50 mm or the like. This is to make it easier to remove each piece by hooking the tape member such as the filament tape and pulling it downward.

[0066] The strip-shaped tape member does not need to be wrapped around all of the pieces, but may be attached to at least the outer pieces of the divided pieces of the hollow form that are farthest from the opening groove 22, such as the left piece 103, left center piece 104, right center piece 107, and right piece 108. However, it is preferable to wrap the tape member around the left piece 103 or right piece 108, which are the most difficult to remove when demolding the hollow form 100.

[0067] In addition, all pieces of the hollow form body 101 according to this embodiment, including the partition steel plate 102, are bundled together by wrapping a strip-shaped filament tape (not shown) of 50 mm width or the like at a pitch of 300 mm. However, it is preferable that the position of this filament tape that bundles the whole together be shifted by 150 mm from the position of the filament tape wrapped around each piece described above.

[0068] (Hollow formwork holding jig) Next, the hollow form holding jig 110 will be described with reference to Figure 11. Figure 11 shows the hollow form holding jig 110 according to this embodiment, where (a) is a front view seen along the longitudinal direction of the precast segment girder 2, and (b) is a plan view showing only the jig body before bolts are attached.

[0069] As shown in Figure 11, the hollow formwork holding jig 110 is a jig whose base is a jig body 111 made of angle iron measuring L65 x 65 x 6 mm. A pair of left and right spacers 112 made of flat bars measuring FB25 x 50 x 50 mm are attached to the underside of both longitudinal ends of this jig body 111 to provide space for installing nuts.

[0070] 11(b), the jig body 111 is provided with five bolt holes for inserting M20 hold-down bolts to prevent the hollow form body 101 from lifting up when pouring concrete. The leftmost bolt hole 113 is a bolt hole for inserting a long side bolt 114 for holding down the side of the hollow form body 101, and is an elongated hole for length adjustment.

[0071] 11(b), the remaining four bolt holes 115 are used to insert short upper surface bolts 116 for holding down the upper surface of the hollow formwork body 101. As shown in FIG.

[0072] 11(a) and 11(b), a steel rod 117 with a diameter of 19 mm and a circular cross section is welded to the underside of the jig body 111 at a position symmetrical to the side bolt 114. When fixing the side surfaces of the hollow formwork body 101, one of the steel rods 117 is fixed and the side bolt 114 is left free to adjust the length, which makes it possible to easily clamp and fix the side surfaces of the hollow formwork body 101 together in a short time.

[0073] (Hollow formwork movement prevention jig) Next, the hollow form movement prevention jig 120 will be described with reference to Figure 12. Figure 12 shows the hollow form movement prevention jig 120 according to this embodiment, where (a) is a front view seen along the longitudinal direction of the precast segment girder 2, and (b) is a plan view showing only the jig body before bolts are attached.

[0074] As shown in Figure 12, the hollow form movement prevention jig 120 is a jig whose base is a jig body 121 made of angle iron measuring L65 x 65 x 6 mm, and is a jig that prevents the hollow form body 101 from shifting and protruding in the horizontal direction when concrete is being poured. Similar to the hollow form holding jig 110 described above, this hollow form movement prevention jig 120 has a pair of left and right spacers 122 made of flat bars measuring FB25 x 50 x 50 mm attached to the underside of both longitudinal ends of the jig body 121 to align the height with the hollow form holding jig 110.

[0075] As shown in FIGS. 12(a) and 12(b), four steel rods 123 each having a diameter of 19 mm and a circular cross section are welded to the lower surface of the jig body 121.

[0076] 12(b), a rectangular pressure plate 124 measuring 4.5 mm thick, 100 mm wide, and 150 mm high is attached to the tip of each steel rod 123. However, the central pressure plate 124 is attached so as to straddle two steel rods 123. These pressure plates 124 have the function of receiving the load with their plate surfaces and preventing the hollow formwork body 101 from shifting horizontally and protruding when concrete is poured.

[0077] (bottom frame) Next, the bottom frame 130 will be described with reference to Fig. 13. Fig. 13 shows the bottom frame 130 according to this embodiment, with (a) being a vertical cross-sectional view perpendicular to the longitudinal direction, (b) being a side view viewed in the horizontal direction, and (c) being a bottom view.

[0078] As shown in Figure 13(a), the bottom frame 130 is composed of an upper plate 131 made of a 6 mm thick steel plate, a lower plate 132 made of a 6 mm thick steel plate, a pair of left and right side plates 133 made of 3.2 mm thick steel plate, and three rib plates 134 made of 6 mm thick steel plate to maintain rigidity. This bottom frame 130 is a formwork for forming the open groove 22 of the precast segment girder 2, and is fixed below the hollow formwork main body 101 (see Figure 6).

[0079] The top plate 131 is made up of a pair of left and right flat bars, each 6 mm thick and 25 mm wide, with a rectangular opening 131a formed in the center of the flat bars. The opening 131a in this embodiment has a width of 63.61 mm, which is narrower than the combined width of the center left piece 105 and the center right piece 106.

[0080] The lower plate 132 is made of a pair of left and right flat bars, each 6 mm thick and 65 mm wide, with a rectangular opening 132a formed in the center of the flat bars. The lower plate 132 also has a pair of left and right long holes 132b drilled therein for fixing to the formwork that forms the outside of the precast segment girder 2.

[0081] Each side plate 133 has a slope at the bottom to form the corners 25 of the precast segment girder 2, and is bent in a dogleg shape in cross section.

[0082] (restraint band) Next, referring to Figure 14, the restraint band 140 is made of a steel plate 1.2 mm thick x 90 mm wide, and is bent into a home plate shape that corresponds to the outer shape of the hollow formwork body 101, i.e., the inner shape of the hollow portion 21, and is welded and joined at the center. Figure 14 shows the restraint band 140 according to this embodiment, where (a) is a front view as seen along the longitudinal direction (axial direction) of the precast segment girder 2, and (b) is a side view.

[0083] Also, as shown in Figure 14(b), the lower end of the restraint band 140 is provided with a bolt hole 140a for joining with an M16 bolt set for wrapping around and fastening the hollow formwork body 101.

[0084] [Manufacturing method for precast segmental girders] Next, a manufacturing method for a precast segment girder according to an embodiment of the present invention will be described with reference to Figures 6 to 14. The manufacturing method for a precast segment girder according to this embodiment differs from the manufacturing method for the conventional pretensioned hollow girder described in the background art in that the hollow portion 21 and the open groove 22 of the precast segment girder 2 manufactured using the hollow formwork 100 for the precast segment girder described above are efficiently manufactured, so this point will be described and other explanations will be omitted.

[0085] (Hollow formwork body assembly process) In the manufacturing method of a precast segment girder according to this embodiment, as shown in Figures 6, 8, 10, and 14, a hollow form body assembly process is carried out to assemble the hollow form body 101 of the hollow form 100 described above. In this hollow form body assembly process, each piece of the hollow form body 101, which is divided by a central partition steel plate 102 and into the six pieces described above - the left piece 103, left center piece 104, central left piece 105, central right piece 106, right center piece 107, and right piece 108 - is covered with a protective resin film F1. At this time, it is preferable that the foamed resin of each piece and the resin film F1 are attached to each other with an adhesive or the like to prevent misalignment.

[0086] This is because when each piece is removed from the hollow form 100, the risk of the resin film F1 being pulled and torn is reduced, making it possible to easily remove the pieces in a short time. However, the foamed resin and the resin film F1 do not necessarily have to be bonded together. This is because if the thickness of the resin film F1 is appropriate, the risk of the resin film F1 being pulled and torn is reduced, and the effort of bonding the resin film F1 can be saved.

[0087] It is also preferable to wrap a tape member of the predetermined width around each piece covered with the resin film F1, in order to make it easier to remove each piece by hooking the tape member such as a filament tape and pulling it downward.

[0088] It is not necessary to wrap this tape member around all pieces, but it may be attached to at least the outer pieces of the divided pieces of the hollow form 100 that are farthest from the opening groove 22, such as the left piece 103, left center piece 104, right center piece 107, and right piece 108. However, it is preferable to wrap the tape member around the left piece 103 or right piece 108, which are the most difficult to remove when demolding the hollow form 100.

[0089] Next, it is preferable to line up the hollow form bodies 101, each piece of which is covered with the resin film F1, and wrap the aforementioned tape member around them at 300 mm intervals before packing them together. The aforementioned restraint bands 140 shown in Figure 14 are then wrapped around the packed hollow form bodies 101 and secured in place by bolts to the bolt holes 102c of the partition steel plates 102. This prevents the separated pieces of the hollow form body 101 from shifting relative to one another during concrete pouring, preventing the hollow section 21 of the precast segment girder 2 from achieving the desired shape.

[0090] Furthermore, the hollow form body 101 may be such that only one of the left and right pieces, for example, the left piece 103, the left-center piece 104, or the center-left piece 105, is covered with the resin film F1 (see FIG. 10). This is because removing one of the left and right pieces of the hollow form body 101 creates a space that allows workers to easily reach in and remove the remaining pieces.

[0091] (Bottom frame installation process) In the manufacturing method for precast segment girder according to this embodiment, as shown in Figures 6, 7 and 13, a bottom frame installation process is performed in which the above-mentioned bottom frame 130 is installed below the hollow formwork main body 101. This bottom frame installation process may be performed simultaneously with or before or after the above-mentioned hollow formwork main body assembly process.

[0092] Specifically, in the bottom frame installation process, the bottom frame 130, which is made up of the above-mentioned upper plate 131, lower plate 132, a pair of left and right side plates 133, and a rib plate 134 joined together, is fixed and installed to the formwork that forms the outside of the precast segment girder 2 using the multiple long holes 132b in the lower plate 132. The bottom frame installation process may be performed simultaneously with or before or after the above-mentioned hollow formwork main body assembly process.

[0093] (Hollow formwork holding jig installation process) Next, in the manufacturing method of the precast segment girder according to this embodiment, as shown in Figures 6, 7 and 12, a hollow formwork clamping jig installation process is carried out in which the aforementioned hollow formwork clamping jig 110 is installed on top of the hollow formwork main body 101 assembled in the hollow formwork main body assembly process to prevent the hollow formwork main body 101 from floating up when concrete is poured.

[0094] Specifically, in the hollow formwork holding jig installation process, a steel rod 117 is abutted against the side of the hollow formwork main body 101, and the fixing position of the side bolt 114 is adjusted using the elongated bolt hole 113, and the sides of the hollow formwork main body 101 are clamped together with the hollow formwork holding jig 110, and the length of the top bolt 116 is adjusted and fixed so that the hollow formwork main body 101 is horizontal.

[0095] (Installation process of a jig to prevent hollow formwork movement) Next, in the manufacturing method of the precast segment girder according to this embodiment, as shown in Figures 7 and 12, a hollow form movement prevention jig installation process is carried out in which a hollow form movement prevention jig 120 is installed at the longitudinal end of the hollow form body 101 assembled in the hollow form body assembly process to prevent the hollow form body 101 from shifting horizontally and protruding when concrete is poured.

[0096] Specifically, in the hollow formwork movement prevention jig installation process, the pressure plate 124 of the hollow formwork movement prevention jig 120 is installed so that it abuts against the longitudinal end of the hollow formwork main body 101, and the plate surface of the pressure plate 124 receives the longitudinal end of the hollow formwork main body 101, preventing the hollow formwork main body 101 from shifting horizontally and protruding when concrete is poured.

[0097] According to the hollow formwork 100 for precast segmental girders and the manufacturing method for precast segmental girders according to the present embodiment described above, the hollow formwork body 101 of the hollow formwork 100 is partitioned by a central partition steel plate 102 and divided into multiple pieces each having a width narrower than the width of the opening groove 22: left piece 103, left center piece 104, central left piece 105, central right piece 106, right center piece 107, and right piece 108. As a result, after concrete is poured, each of the multiple pieces of the hollow formwork 100 can be pulled out of the opening groove 22 and demolded, making it possible to efficiently manufacture a precast segmental girder 2 having an inverted U-shaped cross section, in which deterioration over time can be easily confirmed visually or by using still images, videos, etc.

[0098] Furthermore, according to the hollow formwork 100 for precast segment girder and the manufacturing method for precast segment girder of this embodiment, the divided pieces of the hollow formwork 100 have their abutting portions covered with a resin film F1 and are separated from each other, so that when each piece is pulled out to demold the hollow formwork 100, the frictional force acting between adjacent pieces is reduced, and the hollow formwork 100 can be easily pulled out and demolded in a short time from the opening groove 22 of the precast segment girder 2 where the concrete has hardened.

[0099] Furthermore, according to the hollow formwork 100 for precast segment girders and the manufacturing method for precast segment girders of this embodiment, a tape member is wound around at least the left piece 103 or the right piece 108, which are the most difficult to remove when demolding the hollow formwork 100, so that the outer pieces that are far from the opening groove 22 and difficult to remove can be easily pulled out of the opening groove simply by pulling the tape member.

[0100] Furthermore, according to the hollow formwork 100 for precast segmental girders and the manufacturing method for precast segmental girders of this embodiment, the restraint bands 140 are wrapped around the hollow formwork body 101 and fixed by bolts into the bolt holes 102c of the partition steel plate 102, which serves as a partition plate. This eliminates the problem that the separated pieces of the hollow formwork body 101 move relative to each other during concrete pouring, preventing the hollow portion 21 of the precast segmental girder 2 from taking on the desired shape, and improves the yield rate of the precast segmental girder 2.

[0101] Furthermore, according to the hollow formwork 100 for precast segment girder and the manufacturing method for precast segment girder of this embodiment, a hollow formwork holding jig 110 is installed on top of the hollow formwork main body 101, which prevents each piece of the hollow formwork 100 from floating up and shifting due to buoyancy when pouring concrete, and in this respect too, the yield rate of the precast segment girder 2 can be improved.

[0102] Furthermore, according to the hollow formwork 100 for precast segment girder and the manufacturing method for precast segment girder of this embodiment, a hollow formwork movement prevention jig 120 is installed at the longitudinal end of the hollow formwork main body 101, thereby preventing each piece of the hollow formwork 100 from shifting horizontally relative to each other when pouring concrete, which also improves the yield of the precast segment girder 2.

[0103] Although the hollow formwork 100 for precast segmental girders and the manufacturing method for precast segmental girders according to this embodiment have been described in detail above, the above-described and illustrated embodiments are merely specific embodiments for carrying out the present invention, and therefore the technical scope of the present invention should not be interpreted as being limited by them. [Explanation of symbols]

[0104] 100: Hollow formwork (hollow formwork for precast segmental girders) 101: Hollow formwork body (hollow formwork) 102: Partition steel plate (partition plate) 103: Left Peace 104: Left center piece 105: Center left piece 106: Center right piece 107: Right center piece 108: Right Peace 110: Hollow formwork holding jig 111: Jig body 112: Spacer 113: Bolt hole 114: Side bolt 115: Bolt hole 116: Top bolt 120: Hollow formwork movement prevention jig 121: Jig body 122: Spacer 123: Steel rod 124: Presser plate 130: Bottom frame 131: Top plate 131a: Opening 132: Bottom plate 132a: Opening 132b: Long hole 133: Side plate 134: Rib plate 140: Restraint band 140a: Bolt hole 10: Bridge (precast segment girder) 11: Substructure 11a: Abutment (substructure) 11b: Pier (substructure) 12: Bearing 13:PC steel material (tension material) 1: Superstructure (precast segment girder) 2: Precast segment girder (deck girder) 20: Main body 21: Hollow part 21a: Ceiling surface 21b: Top surface of haunch 22: Opening groove 23:PC steel material 24: Stirrup muscle 25: Corner 3: Deck girder 4,4': Cross beam 40,40':Beam body 41, 41', 42': flange 5: Floor slab 6: Wall parapet 7: Filler section 8: Bulkhead 9: Joint concrete

Claims

1. A hollow formwork for a precast segment girder for forming a hollow portion of a precast segment girder having an inverted U-shaped cross section, in which a lower portion of the hollow portion is opened in a groove-like shape to form an open groove, The hollow form is divided into a plurality of pieces each having a width narrower than the width of the opening groove, After concrete is poured, each of the plurality of pieces of the hollow formwork can be removed from the open groove. Hollow formwork for precast segmental girders characterized by:

2. Each divided piece of the hollow form is separated from the others by being covered with a resin film at least at the contacting portions. The hollow formwork for precast segmental girders according to claim 1,

3. Among the plurality of divided pieces of the hollow form, at least the outer pieces far from the opening grooves are wound with a strip-shaped tape member. The hollow formwork for precast segmental girders according to claim 1,

4. The hollow formwork has a partition plate interposed along the center of the opening groove, and the partition plate is configured to be mechanically fixed to a support body with a bolt. The hollow formwork for precast segmental girders according to claim 1,

5. The hollow form is fixed so as not to float up when concrete is poured by a hollow form holding jig having a holding bolt for preventing the hollow form from floating up when concrete is poured. The hollow formwork for precast segmental girders according to claim 1,

6. The longitudinal ends of the hollow formwork are fixed with a hollow formwork movement prevention jig to prevent horizontal displacement during concrete pouring. The hollow formwork for precast segmental girders according to claim 1,

7. A method for manufacturing a precast segment girder, which uses the hollow formwork for a precast segment girder according to claim 1 to manufacture a precast segment girder having an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, After pouring concrete, each piece of the hollow formwork is removed from the open groove in order. A method for manufacturing precast segmental girders, characterized by:

8. A method for manufacturing a precast segment girder, which uses the hollow formwork for a precast segment girder according to claim 3 to manufacture a precast segment girder having an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, After pouring concrete, the outer piece of the hollow form is removed by pulling the tape member and pulling it out of the open groove. The method for manufacturing a precast segmental girder according to claim 7,

9. A method for manufacturing a precast segment girder, using the hollow formwork for a precast segment girder according to claim 4, to manufacture a precast segment girder having an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, Bolt the partition plate to the support and pour concrete. The method for manufacturing a precast segmental girder according to claim 7,

10. A method for manufacturing a precast segment girder, which uses the hollow formwork for a precast segment girder according to claim 5 to manufacture a precast segment girder having an inverted U-shaped cross section in which a lower part of the hollow portion is opened in a groove-like shape to form an open groove, The hollow form is fixed with the hollow form holding jig so that it does not rise, and concrete is poured. The method for manufacturing a precast segmental girder according to claim 7,

11. A method for manufacturing a precast segment girder, which uses the hollow formwork for a precast segment girder according to claim 6 to manufacture a precast segment girder having an inverted U-shaped cross section in which the lower part of the hollow portion is opened in a groove-like shape to form an open groove, The hollow formwork movement prevention jig is used to fix each piece of the hollow formwork so that it does not shift horizontally relative to each other, and concrete is poured. The method for manufacturing a precast segmental girder according to claim 7,

Images