Hollow formwork for precast segment girders and method for manufacturing precast segment girders

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 mold for a precast segment girder for forming a hollow portion of a precast segment girder having a reverse U-shaped cross section in which the lower part of the hollow portion is open in a groove shape to form an opening groove, and a method for manufacturing a precast segment girder using the same.

Background Art

[0002] [[ID=Il]] Conventionally, there is known a bridge with a hollow floor slab girder that does not have a beam in which a hollow material such as a drum can, which is much lighter than concrete, is embedded for weight reduction. In addition, there is also known a hollow girder in which prestress is applied with a tension member by a pre-tensioning method or a post-tensioning method, and a foamed styrene or the like is embedded in the central part for weight reduction to form a hollow shape with a rectangular cross section. In addition, there are also known a T-girder bridge having a T-shaped girder cross section and a box-girder bridge composed of a box girder in which a large cavity is formed in the bridge to reduce weight without using a hollow material employed in large-scale bridges.

[0003] In addition, a construction method in which various precast members (segments) having different cross-sectional shapes, which are prefabricated in a factory or a site yard in advance, are joined at a bridge erection site, prestressed, and integrated to construct a bridge is called the precast segment method. In particular, among the bridges of precast segment girders constructed by the precast segment method, a hollow girder having a rectangular hollow cross section has excellent cross-sectional performance compared to its weight, and in medium-scale bridges, since the cost performance is good, the number of adopted cases is increasing.

[0004] For example, Patent Document 1 discloses a preten hollow girder bridge in which a preten hollow girder into which prestress is introduced by a pre-tensioning method is integrated with horizontally tightened PC steel materials (see paragraphs

[0019] to

[0027] of the specification of Patent Document 1, FIGS. 3, 4, etc. of the drawings). However, the preten hollow girder described in Patent Document 1 has a problem that it is necessary to provide relatively expensive bearings between a plurality of hollow girders and piers, respectively, and the installation cost of the bearings increases.

[0005] To solve these problems, Patent Document 2 discloses a bridge in which a precast transverse girder 1 is provided on a substructure 4 so as to extend in the direction perpendicular to the bridge axis via a single support device 5 when viewed perpendicular to the bridge axis, the precast transverse girder 1 is continuous in the direction perpendicular to the bridge axis and has a longitudinal girder support flange 6 that extends in the direction perpendicular to the bridge axis, and a plurality of precast longitudinal girders 2 are erected in parallel on the longitudinal girder support flange 6 of the precast transverse girder 1, and the ends of each precast longitudinal girder 2 are integrated (see Claim 1 of the claims in Patent Document 2, paragraphs

[0018] to

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

[0006] However, the precast hollow girders with a square cross-section described in Patent Document 1 and the precast hollow girders with a square cross-section described in Patent Document 2 had the problem that the hollow portion could not be easily inspected after the bridge was completed, making it difficult to detect deterioration over time.

[0007] Therefore, the applicants of this application developed a precast segment girder with an inverted U-shaped cross-section and an open bottom surface in the hollow section, which allows for easy visual inspection, still images, and video recording of deterioration over time. However, the inverted U-shaped precast segment girder requires a folded portion at the bottom of the hollow section for structural integrity, making it difficult to properly demold the formwork for the hollow section of the precast segment girder, resulting in reduced work rate and poor manufacturing efficiency. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2006-169731 [Patent Document 2] Japanese Patent Publication No. 2009-256873 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, the present invention was devised in view of the aforementioned problems, and its objective is to provide a hollow formwork for precast segment girders and a method for manufacturing precast segment girders that can efficiently manufacture precast segment girders with an inverted U-shaped cross-section in which deterioration over time can be easily confirmed by visual inspection, still images, videos, etc. [Means for solving the problem]

[0010] The first invention relates to a hollow formwork for a precast segment girder, which is used to form the hollow portion of a precast segment girder having an inverted U-shaped cross-section, wherein the lower part of the hollow portion is open in the shape of a groove, and the hollow formwork is divided into a plurality of pieces with a width narrower than the width of the opening groove, and is configured to be removable from the opening groove after concrete pouring.

[0011] The second invention is characterized in that, in the first invention, each divided piece of the hollow formwork is separated from each other by having at least the contact portion covered with a resin film.

[0012] The third invention is that, in the first invention, at least the outer piece of the divided plurality of pieces of the hollow formwork that is away from the opening groove has a strip-shaped tape member. Volume It is characterized by being rotated.

[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 the support with bolts.

[0014] The fifth invention is characterized in that, in the first invention, the hollow formwork is fixed in place by a hollow formwork holding jig having holding bolts to prevent it from floating up during concrete pouring.

[0015] The sixth invention is characterized in that, in the first invention, the longitudinal end of the hollow formwork is fixed with a hollow formwork movement prevention jig to prevent it from shifting horizontally during concrete pouring.

[0016] The seventh invention is a method for manufacturing a precast segment girder, in which a precast segment girder with an inverted U-shaped cross-section is manufactured using the hollow formwork for precast segment girders of the first invention, wherein the lower part of the hollow portion is opened in a groove shape to form an opening groove, In the process of assembling a hollow formwork body divided into multiple pieces to form the hollow portion of the precast segment girder, which has an inverted U-shaped cross-section with the lower part of the hollow portion open in a groove shape to form an opening groove, concrete is poured around the formwork to manufacture the precast segment girder with an inverted U-shaped cross-section with the opening groove formed, The method is characterized by removing each piece of the hollow formwork sequentially from the opening groove after the concrete has been poured.

[0017] The eighth invention is a method for manufacturing a precast segment girder, in which, in the seventh invention, a hollow formwork for precast segment girders of the third 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 shape to form an opening groove, characterized in that after concrete is poured, the outer piece of the hollow formwork is removed from the opening groove by pulling the tape member.

[0018] The ninth invention is a method for manufacturing a precast segment girder, in which, in the seventh invention, a hollow formwork for precast segment girders of the fourth 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 shape to form an opening groove, characterized in that the partition plate is bolted to a support and concrete is poured.

[0019] The tenth invention is a method for manufacturing a precast segment girder, in which, in the seventh invention, a hollow formwork for precast segment girders of the fifth 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 shape to form an opening groove, characterized in that the hollow formwork is fixed with the hollow formwork holding jig so as not to lift up and concrete is poured.

[0020] The 11th invention is a method for manufacturing a precast segment girder having a reverse U-shaped cross section in the 7th invention, in which a lower part of a hollow part is opened in a groove shape to form an opening groove, using the hollow formwork for the precast segment girder of the 6th invention, characterized in that concrete is placed while fixing each piece of the hollow formwork so as not to be displaced horizontally from each other by the hollow formwork movement prevention jig.

Effect of the Invention

[0021] According to the 1st to 11th inventions, it is possible to efficiently manufacture a precast segment girder having a reverse U-shaped cross section, in which aging deterioration can be easily confirmed by visual inspection, still images, moving images, etc.

[0022] In particular, according to the 2nd invention, since the abutting portions of the divided pieces of the hollow formwork are covered with a resin film and are separated from each other, when pulling out each piece of the hollow formwork, the frictional force acting on adjacent pieces is reduced, and the hollow formwork can be easily pulled out from the opening groove and demolded in a short time.

[0023] In particular, according to the 3rd and 8th inventions, the outer piece away from the opening groove, which is difficult to remove, can be easily pulled out from the opening groove by simply pulling the tape member.

[0024] In particular, according to the 4th and 9th inventions, each piece of the hollow formwork divided by the partition plate can be firmly fixed without being biased, and it is possible to prevent each piece of the hollow formwork from being displaced during concrete placement, thereby improving the yield of the precast segment girder.

[0025] In particular, according to the 5th and 10th inventions, it is possible to prevent each piece of the hollow formwork from floating and being displaced by buoyancy during concrete placement, thereby improving the yield of the precast segment girder.

[0026] In particular, according to the sixth and eleventh inventions, it is possible to prevent each piece of the hollow formwork from shifting horizontally relative to each other during concrete pouring, thereby improving the work rate of the precast segment girder. [Brief explanation of the drawing]

[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, as cut in a vertical plane perpendicular to the bridge axis. [Figure 2] Figure 2 is an elevation view of the same superstructure, viewed horizontally along the direction perpendicular to the bridge axis. [Figure 3] Figure 3 is a plan view of the same superstructure as above, viewed vertically along the vertical direction. [Figure 4] Figure 4 is a cross-sectional view showing a single precast segment girder of the superstructure shown above, cut along a vertical plane perpendicular to the bridge axis. [Figure 5] Figure 5 is a perspective view showing the crossbeams of the superstructure shown above, where (a) shows the crossbeams installed on the abutments, which are the substructure, and (b) shows the crossbeams installed on the piers. [Figure 6] Figure 6 is a front view along the longitudinal direction (axial direction) of a precast segment girder, showing the overall configuration of a hollow formwork according to an embodiment of the present invention. [Figure 7] Figure 7 is a right side view showing the overall configuration of the hollow formwork described above. [Figure 8] Figure 8 is a front view showing the hollow formwork body of the hollow formwork shown above in an assembled state. [Figure 9] Figure 9 shows the partition steel plate of the hollow formwork described above, where (a) is a front view and (b) is a side view. [Figure 10] Figure 10 is a schematic diagram showing the areas covered by the resin film on each piece of the hollow formwork body shown above. [Figure 11]Figure 11 shows the hollow formwork holding jig for the hollow formwork shown above, where (a) is a front view along the longitudinal direction of the precast segment girder, and (b) is a plan view showing only the jig body before bolt installation. [Figure 12] Figure 12 shows a jig for preventing movement of the hollow formwork, where (a) is a front view along the longitudinal direction of the precast segment girder, and (b) is a plan view showing only the jig body before bolt installation. [Figure 13] Figure 13 shows the bottom frame of the hollow formwork described above, where (a) is a vertical cross-sectional view perpendicular to the longitudinal direction, (b) is a side view seen in the horizontal direction, and (c) is a bottom view. [Figure 14] Figure 14 shows the restraint bands of the hollow formwork shown above, where (a) is a front view along the longitudinal direction (axial direction) of the precast segment girder and (b) is a side view. [Modes for carrying out the invention]

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

[0029] [Precast segment girder] Using Figures 1 to 5, a precast segment girder with an inverted U-shaped cross-section manufactured by the manufacturing method of a precast segment girder according to an embodiment of the present invention will be described. As an example of a precast segment girder according to the embodiment of the present invention, it will be described as one installed in the superstructure 1 of a bridge 10, which is spanned between two substructures 11 consisting of abutments 11a and piers 11b of a bridge 10 made of a deck girder, via bearing devices 12.

[0030] Figure 1 is a cross-sectional view showing the superstructure 1 of a deck girder bridge, which consists of multiple precast segment girders manufactured by a precast segment girder manufacturing method according to an embodiment of the present invention, cut in a vertical plane perpendicular to the bridge axis. Figure 2 is an elevation view of the superstructure 1 viewed horizontally along the direction perpendicular to the bridge axis. Figure 3 is a plan view of the superstructure 1 viewed vertically along the vertical direction. In the figures, the X direction is the first horizontal direction, the bridge axis direction X, and the Y direction is the second horizontal direction perpendicular to the bridge axis Y, which is orthogonal to the X direction. The Z direction indicates the vertical direction Z.

[0031] As shown in Figures 1 to 3, the superstructure 1 of the example bridge (hereinafter also simply referred to as superstructure 1) comprises a deck girder 3 formed by integrating multiple precast segment girders 2, ..., 2, which are manufactured with the horizontal first direction, the bridge axis direction X, as the longitudinal direction. These precast segment girders 2 are placed on the abutments 11a and piers 11b, which are the substructure 11, via multiple precast crossbeams 4. Therefore, the number of bearings 12, which were conventionally required for each precast segment girder 2 and were relatively expensive, can be significantly reduced, thereby lowering the installation cost of the bearings 12.

[0032] (Floor slab girder) Next, the deck girder 3 and the inverted U-shaped precast segment girder 2 will be explained using Figures 1 to 4. Figure 4 is a cross-sectional view showing a single precast segment girder 2 of the superstructure 1 cut in a vertical plane along the direction Y perpendicular to the bridge axis. As shown in Figures 1 to 3, after concrete is poured into the gaps 7 between the precast segment girders 2 and hardened, as shown in Figure 1, multiple precast segment girders 2 of specific shapes are integrated by applying prestress in the direction Y perpendicular to the bridge axis using PC steel members 13, which are tensioning members, in a post-tensioning manner. However, depending on the situation, it is also possible to apply prestress in the direction X perpendicular to the bridge axis using a post-tensioning method.

[0033] (Precast segment girder) Furthermore, as shown in Figure 4, this precast segment girder 2 is mainly formed from a girder body 20 with a rectangular cross-section, similar to that of a conventional pretensioned hollow girder. Therefore, conventional formwork can be used as is, preventing increased costs. However, conventional hollow girders had the problem that it was not possible to visually inspect for rust or cracks inside the hollow section with a pentagonal cross-section.

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

[0035] Furthermore, as shown in Figure 4, the precast segment girder 2 is a pre-tensioned precast (PCPCa) girder in which multiple PC steel members 23 are inserted through the girder body 20 and prestress is applied using a pretensioning method, similar to conventional pre-tensioned hollow girders. Of course, if the span of the girder is short, it is not necessary to apply prestress using a pretensioning method. Also, precasting is not limited to cases where concrete is poured in advance at a factory or the like, but also includes cases where concrete is poured in advance at a separate yard near the site, with or without human intervention, including the use of 3D printers.

[0036] As shown in Figure 4, the multiple PC steel members 23 of the girder body 20 are surrounded and enclosed by stirrup reinforcement 24 made of steel such as D10, ensuring bending rigidity. The spacing of the PC steel members 23 is the same as that of conventional pre-tempered hollow girders so as not to change the dimensions of the tension abutments. This allows for the use of existing facilities, which in turn reduces manufacturing costs.

[0037] Furthermore, as mentioned above, since an opening groove 22 is formed on the lower surface of the girder body 20, the ceiling surface 21a of the hollow section 21 can be easily confirmed by visual inspection. However, the haunch upper surface 21b of the hollow section 21 shown in Figure 4 has a haunch inclination angle of 45 degrees, D2 = 140 mm × D2 = 140 mm in the illustrated configuration, and at the eye level angle indicated by the dashed arrow, it is difficult to see using only the width D1 of the opening groove 22. For this reason, in the precast segment girder 2 according to this embodiment, the inner corner portion 25 facing the open lower surface with an inverted U-shaped cross-section is chamfered in a straight line according to the inclination angle of the haunch. Of course, this corner portion 25 is not limited to being chamfered in a straight line, but may also be chamfered in a curved shape. In either case, the visibility of the haunch upper surface 21b of the hollow section 21 is improved while ensuring the required strength by reducing the width D1 of the opening groove 22.

[0038] (Horizontal beam) Next, the crossbeam 4 will be explained using Figures 1 to 3 and Figure 5. Figure 5 is a perspective view showing the crossbeam 4 of the superstructure 1, where (a) shows the crossbeam 4 installed on the abutment, which is the substructure, and (b) shows the crossbeam 4' installed on the pier. The crossbeam 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 crossbeams: a crossbeam 4 installed on the abutment 11a with an L-shaped cross section in a vertical cross section perpendicular to the longitudinal direction, and a crossbeam 4' installed on the pier 11b with a convex cross section in a vertical cross section perpendicular to the longitudinal direction.

[0039] As shown in Figure 5(a), the crossbeam 4 comprises a rectangular beam body 40 with a vertically elongated cross-section, and a flange 41 that supports the longitudinal end of the beam body 40, which extends in one direction in the bridge axis direction X. The beam depth (height) of the beam body 40 is set so that when the precast segment girder 2 is placed on the flange 41, the upper surface of the beam body 40 and the upper surface of the precast segment girder 2 are at approximately the same height (see Figure 2).

[0040] Furthermore, as shown in Figure 5(b), the crossbeam 4' comprises a rectangular beam body 40' with a vertically elongated cross-section, and flanges 41' and 42' that support the longitudinal ends of the precast segment girders 2 that extend from the beam body 40' in both directions along the bridge axis X. The beam depth (height) of the beam body 40' is set so that the upper surface of the beam body 40' is lower than the upper surface of the precast segment girders 2, so that there is space to pour concrete to integrate the precast segment girders 2, 2 when they are placed on the flanges 41' and 42' (see Figure 2).

[0041] Although a precast concrete crossbeam was used as an example in this embodiment, a regular cast-in-place reinforced concrete crossbeam may also be used instead of a precast one. While cast-in-place crossbeams may take slightly longer to construct compared to precast ones, it is clear that installing the main girders on the bridge piers via the crossbeams reduces the number of support devices 12 required for each main girder.

[0042] (Gap filler) Furthermore, when bridging the precast segment girder 2 between the flanges 41 (flanges 41', 42') of the aforementioned crossbeam 4(4'), it is preferable to lay gap-filling material (not shown) on the flanges 41 (flanges 41', 42') before placing the longitudinal ends of the precast segment girder 2 on the flanges 41 (flanges 41', 42'). By doing so, even if there is warping or unevenness on the upper surface of the flanges 41 (flanges 41', 42') or the lower surface of the precast segment girder 2, the gap between the crossbeam 4(4') and the precast segment girder 2 can be filled, and stress acting on the superstructure 1, such as live loads, can be evenly transmitted to the substructure 11. This improves the durability of the superstructure 1.

[0043] As gap fillers, pressure-sensitive hardening rubber, self-leveling materials, and non-shrink mortars are preferred because they can reliably fill gaps without requiring much effort. Alternatively, polymer-based resins may also be used as gap fillers, and composites or laminates of two or more of the following materials—pressure-sensitive hardening rubber, non-shrink mortar, and resin—can also be applied.

[0044] (Floor slab and railing) Furthermore, as shown in Figure 1, a flat deck slab 5 is formed on a deck girder 3 consisting of multiple precast segment girders 2, and a wall parapet 6 is provided along the edge of the deck slab 5, which is the end in the direction Y perpendicular to the bridge axis. However, the deck slab 5 and parapet 6 shown in Figure 1 are made of typical cast-in-place reinforced concrete, and a detailed explanation is omitted.

[0045] (Insulated section) As shown in Figures 1 and 3, the space (gap) along the bridge axis X between a precast segment girder 2 adjacent to another precast segment girder 2 in the direction Y perpendicular to the bridge axis is the gap 7. Concrete is poured into this gap 7 on site, and as the poured concrete hardens, gap-filling concrete is formed, thereby integrating multiple precast segment girders 2 adjacent to each other in the direction Y perpendicular to the bridge axis.

[0046] Although the explanation has been given using the example of pouring concrete into the gap 7, the gap 7 can be filled with any filler material that hardens over time, such as concrete, mortar, gypsum, or other substances that harden through a hydration reaction, as well as time-hardening substances that harden over time and can withstand the compressive force acting on the gap 7. In particular, when the width of the gap 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, as this can shorten the curing period and construction period.

[0047] (bulkhead) Furthermore, as shown in Figures 2 and 3, multiple precast segment girders 2 arranged in parallel in the direction Y perpendicular to the bridge axis are integrated with partition walls 8 made of cast-in-place reinforced concrete at predetermined intervals to resist horizontal forces. In other words, the portion of the precast segment girder 2 where the lower surface of the hollow cross-section is open and the cross-section is inverted U-shape constitutes a part of the girder's length. In other words, a portion of the precast segment girder 2 in the length direction of the girder has its inverted U-shape closed and has a rectangular cross-section.

[0048] Specifically, the precast segment girders 2 of the general section, which are the middle girders located on the inside, are equipped with bulkheads 8 at predetermined intervals calculated by structural calculations in the bridge axis direction X, excluding the outermost girder 2'. The outermost girder 2' is equipped with bulkheads 8 at shorter intervals.

[0049] In the illustrated configuration, the outermost girder 2' is provided with two or more bulkheads 8 at predetermined intervals, twice the usual number. This is because the outer girder 2' is directly subjected to lateral loads such as wind loads and collision loads, compared to the precast segment girder 2 of the general section, which is the middle girder. By providing bulkheads 8 in this way, even if the underside of the girder body 20, which has a weaker rectangular cross-section than conventional hollow girders, is made open in an inverted U-shape, it can withstand lateral loads such as wind loads and collision loads.

[0050] (Concrete joint) As shown in Figures 2 and 3, the connection of the precast segment girders 2 on the pier 11b in the bridge axis direction X is made by pouring construction joint concrete 9 after the predetermined reinforcement has been installed. This construction joint concrete 9 can also be made of a filler material other than concrete that hardens over time, similar to the infill concrete 7.

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

[0052] Furthermore, since the corners 25 of the precast segment girder 2 of the superstructure 1 are chamfered, the inside of the hollow section 21 of the precast segment girder 2 becomes easier to observe visually, with still images, or with video, making it easier to detect deterioration over time and facilitating repairs.

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

[0054] Furthermore, since the superstructure 1 can install bearing devices 12 between the substructure 11 and the precast segment girders 2 of the superstructure 1 via crossbeams 4(4'), the number of expensive bearing devices 12 required for each girder can be reduced, thereby reducing the construction cost of the bridge's superstructure 1.

[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 outermost girder 2' is provided with bulkheads 8 at shorter intervals. Therefore, even if opening 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, instead of providing an opening groove 22 along the entire length of the precast segment girder 2 of the superstructure 1, by closing off a portion of the girder in the length direction and providing an opening groove 22 only in a portion of the length direction, it is possible to resist horizontal forces acting as external forces in the same way as the partition wall 8, without having to cast the partition wall 8 in place.

[0057] [Hollow formwork for precast segment girders] Next, using Figures 6 to 14, the hollow formwork 100 for the precast segment girder and its accessories for forming the hollow portion 22 of the aforementioned precast segment girder 2 used in the manufacturing method of the precast segment girder according to the embodiment of the present invention will be described in detail. Figure 6 is a front view of the hollow formwork 100 according to the embodiment of the present invention, viewed along the longitudinal direction (axial direction) of the aforementioned precast segment girder 2 to be manufactured, and Figure 7 is a right side view showing the overall configuration of the hollow formwork 100. Note that the formwork that forms the outside of the precast segment girder 2 is equivalent to the formwork of a conventional pre-tempered hollow girder, and is not shown and its description is omitted.

[0058] As shown in Figures 6 and 7, the hollow formwork 100 consists of a hollow formwork body 101 divided into multiple sections, a hollow formwork holding jig 110 that holds the hollow formwork body 101 in place to prevent it from lifting, a hollow formwork movement prevention jig 120 that prevents the hollow formwork body 101 from moving horizontally, a bottom frame 130 for forming the opening groove 22 of the aforementioned precast segment girder 2, and a restraining band 140 that holds the multiple divided hollow formwork body 101 together.

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

[0060] Figure 9 shows the partition steel plate 102, where (a) is a front view and (b) is 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 parts, and the partition steel plate 102 shown in Figure 9 has the function of dividing the hollow formwork body 101 into left and right halves with a pair of front and rear plates. However, the partition plate according to the present invention is not limited to a steel plate, and any member with a predetermined strength and rigidity that can partition each piece of the hollow formwork 100 so that it does not shift when concrete is poured may be used.

[0061] As shown in Figure 9, the partition steel plate 102 consists of a rectangular steel plate body 102a with a length L1 = 988 mm, a height H1 = 440 mm, and a thickness of 3.2 mm, and two tab pieces 102b that protrude 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.

[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 their edges cut off to facilitate removal. Figure 10 is a schematic diagram showing the area of ​​each piece of the hollow formwork body 101 that is covered with the resin film F1.

[0063] As shown in Figure 10, in this embodiment, the hollow formwork body 101 has the left piece 103, left middle piece 104, right middle piece 107, and right piece 108, which are located on the outside and are difficult to remove, covered with a resin film F1 around their entire circumference, while the central left piece 105 and central right piece 106, which are easy to remove, are covered only within a range of 100 mm from the top and bottom ends. Furthermore, it is preferable that the foamed resin and the resin film F1 are bonded to each other with an adhesive or the like to prevent them from shifting. This reduces the risk of the protective resin film F1 being pulled and torn when removed, making it possible to remove them easily and quickly. However, the foamed resin and the resin film F1 do not necessarily have to be bonded together. If the thickness of the resin film F1 is appropriate, there is less risk of the resin film F1 being pulled and torn, and the effort of bonding is saved.

[0064] Furthermore, the hollow formwork body 101 may only have one of its left or right pieces, for example, the left piece 103, the left-center piece 104, and the center-left piece 105, covered with the resin film F1. This is because removing one of the left or right pieces of the hollow formwork body 101 creates space, making it easy for workers to reach in and remove the remaining pieces.

[0065] Furthermore, in this embodiment, each piece of the hollow formwork body 101 is covered with a resin film F1, and then wrapped around it at 300 mm intervals with a tape member such as a strip-shaped filament tape (not shown) with a width of 50 mm or more. Volume It is preferable to leave it rotating. This makes it easier to remove each piece by hooking the tape material, such as filament tape, onto it and pulling it downwards.

[0066] Note that the strip-shaped tape material is applied to all pieces. Volume There is no need to rotate it; it is sufficient to attach it to at least the outer pieces of the divided hollow formwork that are away from the opening groove 22, such as the left piece 103, the left middle piece 104, the right middle piece 107, or the right piece 108. However, the tape member should be attached to the left piece 103 or the right piece 108, which are the most difficult to remove when demolding the hollow formwork 100. Volume It is preferable to keep it running.

[0067] In addition, the hollow formwork body 101 according to this embodiment, including the partition steel plate 102, is constructed with strip-shaped filament tape (not shown) of a width of 50 mm or more at 300 mm intervals. Volume It is wrapped and bundled together. However, the position of the filament tape that bundles the whole thing together is around each of the aforementioned pieces. Volume It is preferable to offset the position of the rotated filament tape by 150 mm.

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

[0069] As shown in Figure 11, the hollow formwork retaining jig 110 is a jig based on a jig body 111 made of angle steel measuring L65 × 65 × 6 mm. A pair of spacers 112 made of FB25 × 50 × 50 mm flat bars are attached to the lower surfaces of both ends in the longitudinal direction of the jig body 111 to create space for mounting nuts.

[0070] Furthermore, as shown in Figure 11(b), the jig body 111 has five bolt holes for inserting M20 retaining bolts to prevent the hollow formwork body 101 from lifting up during concrete pouring. The leftmost bolt hole 113 is for inserting a long side bolt 114 that secures the side of the hollow formwork body 101, and is an elongated hole for length adjustment.

[0071] As shown in Figure 11(b), the remaining four bolt holes 115 are bolt holes through which short top bolts 116 are inserted to secure the top surface of the hollow formwork body 101.

[0072] As shown in Figures 11(a) and 11(b), a steel rod 117 with a diameter of 19 mm and a circular cross-section is welded to the lower surface of the jig body 111 at a position symmetrical to the side bolts 114. This is to allow for easy and quick clamping and fixing of the sides of the hollow formwork body 101 by fixing one side of the steel rod 117 and leaving the side of the side bolt 114 free to adjust the length.

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

[0074] As shown in Figure 12, the hollow formwork movement prevention jig 120 is a jig based on a jig body 121 made of angle steel measuring L65 × 65 × 6 mm, and is a jig for preventing the hollow formwork body 101 from shifting horizontally and protruding during concrete pouring. Similar to the hollow formwork holding jig 110 described above, the hollow formwork movement prevention jig 120 has a pair of left and right spacers 122 made of FB25 × 50 × 50 mm flat bars attached to the lower surface of both ends in the longitudinal direction of the jig body 121 to match the height of the hollow formwork holding jig 110.

[0075] Furthermore, as shown in Figures 12(a) and 12(b), four steel rods 123 with a diameter of 19 mm and a circular cross-section are welded to the lower surface of the jig body 121.

[0076] As shown in Figure 12(b), a rectangular retaining plate 124 measuring 4.5 mm thick x 100 mm wide x 150 mm high is attached to the tip of each steel rod 123. However, the central retaining plate 124 is attached across both steel rods 123. These retaining plates 124 have the function of supporting the hollow formwork body 101 with their plate surfaces to prevent it from shifting horizontally and protruding during concrete pouring.

[0077] (bottom frame) Next, the bottom frame 130 will be described using Figure 13. Figure 13 is a diagram showing the bottom frame 130 according to this embodiment, where (a) is a vertical cross-sectional view perpendicular to the longitudinal direction, (b) is a side view seen in the horizontal direction, and (c) is a bottom view.

[0078] As shown in Figure 13(a), the bottom frame 130 is composed of an upper plate 131 made of 6 mm thick steel plate, a lower plate 132 made of 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 opening groove 22 of the precast segment girder 2 and is fixed below the hollow formwork body 101 (see Figure 6).

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

[0080] The bottom plate 132 consists of a pair of flat bars, each 6 mm thick and 65 mm wide, with a rectangular opening 132a formed in the center of these flat bars. The bottom plate 132 also has a pair of elongated holes 132b drilled into it, which are used to fix it to the formwork that forms the outside of the precast segment girder 2.

[0081] Each side plate 133 has an inclination formed at its lower end to form the corner 25 of the precast segment girder 2, and is bent in a V-shape in cross-section.

[0082] (Restraint band) Next, using Figure 14, the restraint band 140 is made of a steel plate with a thickness of 1.2 mm and a width of 90 mm, and is bent into a home plate shape according to the outer shape of the hollow formwork body 101, that is, the inner shape of the hollow section 21, and is welded and joined in the center. Figure 14 is a diagram showing the restraint band 140 according to this embodiment, where (a) is a front view along the longitudinal direction (axial direction) of the precast segment girder 2, and (b) is a side view.

[0083] Furthermore, 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, which is used to wrap around and fasten the hollow formwork body 101.

[0084] [Manufacturing method for precast segment girders] Next, a method for manufacturing a precast segment girder according to an embodiment of the present invention will be described using Figures 6 to 14. The difference between the method for manufacturing a precast segment girder according to this embodiment and the conventional method for manufacturing a pre-tempered hollow girder described in the background art is that it efficiently manufactures the hollow portion 21 and the opening groove 22 of the precast segment girder 2, which is manufactured using the aforementioned hollow formwork 100 for precast segment girders. This point will be explained, and other explanations will be omitted.

[0085] (Hollow formwork main assembly process) In the manufacturing method of the precast segment girder according to this embodiment, as shown in Figures 6, 8, 10, and 14, a hollow formwork body assembly step is performed to assemble the hollow formwork body 101 of the aforementioned hollow formwork 100. In this hollow formwork body assembly step, each piece of the hollow formwork body 101, which is divided into six parts by a central partition steel plate 102—the left piece 103, left-center piece 104, center-left piece 105, center-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 shifting.

[0086] This is because, when removing each piece during demolding of the hollow mold 100, the risk of the resin film F1 being pulled and torn is reduced, making it possible to remove them easily and quickly. However, the foamed resin and the resin film F1 do not necessarily need to be bonded together. If the thickness of the resin film F1 is appropriate, the risk of the resin film F1 being pulled and torn is reduced, saving the effort of bonding.

[0087] Furthermore, it is preferable to wrap the aforementioned tape member of a predetermined width around each piece covered with the resin film F1. This is to make it easier to remove each piece by hooking the tape member, such as filament tape, onto it and pulling it downwards.

[0088] Note that it is not necessary to wrap this tape around all pieces; it is sufficient to attach it to at least the outer pieces of the hollow formwork 100 that are furthest from the opening groove 22, such as the left piece 103, the left middle piece 104, the right middle piece 107, and the right piece 108. However, it is preferable to wrap the tape around the left piece 103 or the right piece 108, which are the most difficult to remove when demolding the hollow formwork 100.

[0089] Subsequently, it is preferable to arrange the hollow formwork bodies 101, each piece covered with resin film F1, and wrap the aforementioned tape material around them at 300 mm intervals to package them together. Furthermore, the aforementioned restraint band 140 shown in Figure 14 is wrapped around the packaged hollow formwork bodies 101 and bolted to the bolt holes 102c of the partition steel plate 102 to secure them. This eliminates the problem that when concrete is poured, the individual pieces of the divided hollow formwork bodies 101 move relative to each other, preventing the hollow section 21 of the precast segment girder 2 from taking the desired shape.

[0090] Furthermore, the hollow formwork body 101 may only have one of its left or right pieces, for example, the left piece 103, the left-center piece 104, and the center-left piece 105, covered with resin film F1 (see Figure 10). This is because removing one of the left or right pieces of the hollow formwork body 101 creates space, making it easy for a worker to reach in and remove the remaining piece.

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

[0092] Specifically, in this bottom frame installation process, the bottom frame 130, to which the aforementioned top plate 131, bottom plate 132, a pair of left and right side plates 133, and rib plate 134 are joined, is fixed and installed to the formwork that forms the outside of the precast segment girder 2 using the multiple elongated holes 132b in the bottom plate 132. This bottom frame installation process may be performed simultaneously with or before / after the aforementioned hollow formwork main 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 holding jig installation step is performed in which the aforementioned hollow formwork holding jig 110, which prevents the hollow formwork body 101 from floating up when concrete is poured, is installed on top of the hollow formwork body 101 assembled in the hollow formwork body assembly step.

[0094] Specifically, in the hollow formwork holding jig installation process, the steel rod 117 is brought into contact with the side of the hollow formwork body 101, the fixing position of the side bolts 114 is adjusted using the elongated bolt holes 113, and the sides of the hollow formwork body 101 are sandwiched together with the hollow formwork holding jig 110. The length of the top bolts 116 is then adjusted and fixed so that the hollow formwork body 101 is horizontal.

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

[0096] Specifically, in the hollow formwork movement prevention jig installation process, the retaining plate 124 of the hollow formwork movement prevention jig 120 is installed so that it contacts the longitudinal end of the hollow formwork body 101, and the plate surface of the retaining plate 124 supports the longitudinal end of the hollow formwork body 101, preventing the hollow formwork body 101 from shifting horizontally and protruding during concrete pouring.

[0097] According to the hollow formwork 100 for precast segment girders and the manufacturing method for precast segment girders according to the embodiment described above, the hollow formwork body 101 of the hollow formwork 100 is partitioned by a central partition steel plate 102 and is divided into multiple pieces with widths narrower than the width of the opening grooves 22: left piece 103, left-center piece 104, center-left piece 105, center-right piece 106, right-center piece 107, and right piece 108. Therefore, after concrete pouring, each of the multiple pieces of the hollow formwork 100 can be removed from the opening grooves 22 and demolded, and a precast segment girder 2 with an inverted U-shaped cross-section, in which deterioration over time can be easily confirmed by visual inspection, still images, videos, etc., can be efficiently manufactured.

[0098] Furthermore, according to the hollow formwork 100 for precast segment girders and the manufacturing method for precast segment girders according to this embodiment, since the contact portions of each divided piece of the hollow formwork 100 are covered with a resin film F1 and separated from each other, when each piece is pulled out during demolding of the hollow formwork 100, the frictional force acting between adjacent pieces is reduced, and the hollow formwork 100 can be easily removed from the opening groove 22 of the precast segment girder 2 in a short time.

[0099] Furthermore, according to the hollow formwork 100 for precast segment girders and the manufacturing method for precast segment girders according to this embodiment, since the tape member is wrapped 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, the outer piece, which is far from the opening groove 22 that is 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 segment girders and the manufacturing method of the precast segment girders according to this embodiment, a restraining band 140 is wrapped around the hollow formwork body 101 and fixed by bolting it to the bolt holes 102c of the partition steel plate 102, which is a partition plate. As a result, the problem of each piece of the divided hollow formwork body 101 moving relative to each other during concrete pouring, which would prevent the hollow portion 21 of the precast segment girder 2 from taking the desired shape, can be eliminated, and the production rate of the precast segment girder 2 can be improved.

[0101] Furthermore, according to the hollow formwork 100 for precast segment girders and the manufacturing method of the precast segment girders according to this embodiment, since the hollow formwork holding jig 110 is installed on the hollow formwork body 101, it is possible to prevent each piece of the hollow formwork 100 from floating up and shifting due to buoyancy during concrete pouring, and in this respect as well, the work rate of the precast segment girders 2 can be improved.

[0102] Furthermore, according to the hollow formwork 100 for precast segment girders and the manufacturing method of the precast segment girders according to this embodiment, a hollow formwork movement prevention jig 120 is installed at the longitudinal end of the hollow formwork body 101, which prevents each piece of the hollow formwork 100 from shifting horizontally relative to each other during concrete pouring, and in this respect as well, the work rate of the precast segment girders 2 can be improved.

[0103] Although the hollow formwork 100 for precast segment girders and the method for manufacturing precast segment girders according to this embodiment have been described in detail above, the embodiments described above or illustrated are merely examples of embodiments that have been materialized in carrying out the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these embodiments. [Explanation of symbols]

[0104] 100: Hollow formwork (Hollow formwork for precast segment girders) 101: Hollow formwork body (hollow formwork) 102: Partition steel plate (partition plate) 103: Left piece 104: Left-center piece 105: Center left piece 106: Center right piece 107: Right-center piece 108: Right piece 110: Hollow formwork retaining jig 111: Jig body 112: Spacer 113: Bolt hole 114: Side bolts 115: Bolt hole 116: Top bolt 120: Hollow formwork movement prevention jig 121: Jig body 122: Spacer 123: Steel rod 124: Retaining 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: Bridge pier (substructure) 12: Bearing 13:PC steel material (tension material) 1: Superstructure (precast segment girder) 2: Precast segment girder (deck girder) 20: Digit body 21: Hollow part 21a: Ceiling surface 21b: Top surface of haunch 22: Opening groove 23:PC steel material 24: Stirrup muscles 25: Corner 3: Deck slab girder 4,4': Cross beam 40,40':Beam body 41, 41', 42': Flange 5: Floor slab 6: Wall railing 7: Gap filling section 8: Bulkhead 9: Concrete joint

Claims

1. A hollow formwork for a precast segment girder, for forming the hollow portion of a precast segment girder with an inverted U-shaped cross-section, wherein the lower part of the hollow portion is opened in a groove-like manner to form an opening groove, The hollow formwork is divided into multiple pieces, each with a width narrower than the width of the opening groove. The hollow formwork is configured to be removable after concrete pouring by removing each of the multiple pieces from the opening groove. A hollow formwork for precast segment girders characterized by the following.

2. Each divided piece of the hollow formwork is separated from each other by having at least the contact portion covered with a resin film. A hollow formwork for a precast segment girder according to claim 1, characterized by the above.

3. At least one of the divided pieces of the hollow formwork, the outer piece away from the opening groove, is wrapped with a strip-shaped tape member. A hollow formwork for a precast segment girder according to claim 1, characterized by the above.

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 the support with bolts. A hollow formwork for a precast segment girder according to claim 1, characterized by the above.

5. The aforementioned hollow formwork is secured in place during concrete pouring by a hollow formwork holding jig that has retaining bolts to prevent it from lifting up during concrete pouring. A hollow formwork for a precast segment girder according to claim 1, characterized by the above.

6. The longitudinal ends of the aforementioned hollow formwork are fixed with a hollow formwork movement prevention jig to prevent horizontal displacement during concrete pouring. A hollow formwork for a precast segment girder according to claim 1, characterized by the above.

7. A method for manufacturing a precast segment girder, in which a precast segment girder with an inverted U-shaped cross-section is manufactured using the hollow formwork for precast segment girders described in claim 1, wherein the lower part of the hollow portion is opened in a groove shape to form an opening groove, In the process of assembling a hollow formwork body divided into multiple pieces to form the hollow portion of the precast segment girder, which has an inverted U-shaped cross-section with an opening groove formed at the lower part of the hollow section, concrete is poured around the hollow formwork to manufacture the precast segment girder with an inverted U-shaped cross-section with the opening groove formed, and after the concrete is poured, each piece of the hollow formwork is sequentially removed from the opening groove to demold. A method for manufacturing precast segment girders characterized by the following.

8. A method for manufacturing a precast segment girder, in which a precast segment girder with an inverted U-shaped cross-section is manufactured using the hollow formwork for precast segment girders described in claim 3, wherein the lower part of the hollow portion is opened in a groove shape to form an opening groove, After concrete is poured, the outer piece of the hollow formwork is removed by pulling the tape member and pulling it out of the opening groove. A method for manufacturing a precast segment girder according to claim 7, characterized by the above.

9. A method for manufacturing a precast segment girder, in which a precast segment girder with an inverted U-shaped cross-section is manufactured using the hollow formwork for precast segment girders described in claim 4, wherein the lower part of the hollow portion is opened in a groove shape to form an opening groove, The partition plate is bolted to the support and concrete is poured. A method for manufacturing a precast segment girder according to claim 7, characterized by the above.

10. A method for manufacturing a precast segment girder, in which a precast segment girder with an inverted U-shaped cross-section is manufactured using the hollow formwork for precast segment girders described in claim 5, wherein the lower part of the hollow portion is opened in a groove shape to form an opening groove, The hollow formwork is fixed in place using the aforementioned hollow formwork holding jig to prevent it from lifting, and then concrete is poured. A method for manufacturing a precast segment girder according to claim 7, characterized by the above.

11. A method for manufacturing a precast segment girder, in which a precast segment girder with an inverted U-shaped cross-section is manufactured using the hollow formwork for precast segment girders described in claim 6, wherein the lower part of the hollow portion is opened in a groove shape to form an opening groove, The hollow formwork is fixed in place using the aforementioned hollow formwork movement prevention jig so that each piece of the hollow formwork does not shift horizontally relative to one another, and then concrete is poured. A method for manufacturing a precast segment girder according to claim 7, characterized by the above.

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