Concrete wall railing and construction method thereof

Abstract

To provide a concrete wall railing with high work efficiency, capable of shortening a construction period and its construction method.SOLUTION: A concrete wall railing 5 includes a pair of precast buried form boards 6, 7 arranged on a side part of a concrete floor slab 4 at an interval in a wall thickness direction, anchoring reinforcing bars 8, 8. projecting from an upper surface of the concrete floor slab 4 between the precast buried form boards 6, 7 and installed at an interval in a bridge axial direction, reinforcing vertical reinforcement bodies 20, 20 connected to the anchoring reinforcing bars 8, 8., a plurality of horizontal reinforcements 21, 21 supported by the reinforcing vertical reinforcement bodies 20, 20, and a cast-in-place concrete part 10 placed between the precast buried forms boards 6, 7.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a concrete wall parapet provided on the side of a deck of a bridge, an elevated road, etc., and a method for constructing the same. [Background technology]

[0002] On both sides of concrete decks of bridges, elevated roads, etc., continuous reinforced concrete wall parapets are provided in the bridge axis direction for the purpose of preventing vehicles from falling or straying, guiding the line of sight, etc.

[0003] In this type of concrete wall parapet, loads due to wind and loads generated when a vehicle hits the wall are taken into consideration, and vertical bars are arranged in two rows at intervals in the direction of the wall thickness at a specified interval in the bridge axis direction, and reinforcing bars with diagonal bars are arranged to span and support the vertical bars arranged in two rows at intervals in the direction of the wall thickness. These vertical bars and reinforcing bars are connected to anchor steel bars embedded in the concrete floor slab using a lap joint structure or the like, thereby integrating the wall parapet and the concrete floor slab.

[0004] On the other hand, bridges, elevated roads, etc. have deteriorated in recent years due to the long time that has passed since they were opened, and the need for replacement and repair work (renewal work) has been increasing.

[0005] In such renovation work, it is necessary to suspend road use, so it is desirable to drastically shorten the construction period. For this reason, there are many cases where precast decks are used.

[0006] In the past, concrete wall parapets were typically constructed using cast-in-place concrete, but in order to shorten construction times in renovation work, construction methods using precast components, just like with deck slabs, are now widely adopted.

[0007] A known method of constructing a concrete wall balustrade using precast concrete members is to, for example, protrude anchor bolts upward from the upper side surface of the concrete deck, place the precast member for the wall balustrade on top so that the anchor bolts are inserted into bolt holes opening in the bottom surface, and fill the bolt holes with filler to integrate the concrete deck and the precast member for the wall balustrade (see, for example, Patent Document 1).

[0008] Another known construction method involves protruding anchoring rebars made of loop bars or the like from the upper side surface of the concrete deck, placing a precast member for the wall balustrade above it at a distance from the concrete deck, overlapping the anchoring rebars on the precast member side that protrude from the bottom surface of the precast member to form a lap joint, and then pouring concrete into the gap between the concrete deck and the precast member to integrate the concrete deck and the precast member for the wall balustrade (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2018-165467 A [Patent Document 2] Patent No. 5847483 Summary of the Invention [Problem to be solved by the invention]

[0010] However, with the conventional technology described above, the precast components for the parapets are heavy (for example, approximately 1.8 to 2.3 tons for a bridge with a length in the bridge axis direction of 2.5 m), which means that a large crane is needed to hoist the precast components, making installation work of the precast components complicated.

[0011] Furthermore, with conventional construction methods, the work of inserting and connecting the anchor bolts and fixed rebars on the concrete deck to the bolt holes and fixed rebars on the precast members was not easy, requiring a great deal of time and effort, which hindered efforts to shorten construction periods.

[0012] In particular, in a construction method such as that described in Patent Document 2, it is necessary to assemble reinforcing bars and pour cast-in-place concrete in the narrow space between the precast deck and the wall parapet, which makes it difficult to carry out the work smoothly.

[0013] In view of the above-mentioned problems, the present invention has been made with an object to provide a concrete wall parapet and a method for constructing the same that can improve work efficiency and shorten the construction period. [Means for solving the problem]

[0014] The feature of the invention described in claim 1 for solving the above-mentioned conventional problems is that a concrete wall parapet is installed on the side of a concrete floor slab, the parapet comprises a pair of precast embedded formwork slabs arranged at intervals from each other in the wall thickness direction on the sides of the concrete floor slab, anchorage steel bars protruding from the top surface of the concrete floor slab between the precast embedded formwork slabs and installed at intervals in the bridge axis direction, reinforcing vertical bars arranged at intervals in the bridge axis direction between the precast embedded formwork slabs and connected to the anchorage steel bars, a plurality of horizontal bars supported across the reinforcing vertical bars in the bridge axis direction, and a cast-in-place concrete section poured between the precast embedded formwork, the reinforcing vertical bars comprising vertical bar sections consisting of inner vertical bars and outer vertical bars arranged at intervals in the wall thickness direction, and reinforcing bars having diagonal bar sections supported across the inner vertical bars and the outer vertical bars, the vertical bar sections and reinforcing bars being connected to the anchorage steel bars.

[0015] The feature of the invention described in claim 2 is that, in addition to the configuration of claim 1, each of the precast embedded formwork slabs has an internal reinforcing bar having a bent convex portion bent across straight sections embedded inside the formwork slab, and the bent convex portion protrudes toward the opposing surface.

[0016] The feature of the invention described in claim 3 is that, in addition to the configuration of claim 2, the invention is provided with an internal support structure whose ends are fixed to the bent convex portions protruding toward the opposing surfaces of the two opposing precast buried formworks and supported across the precast buried formworks, and the reinforcing vertical reinforcement members are supported on each of the precast buried formworks via the internal support structure.

[0017] The invention as recited in claim 4 is characterized in that, in addition to the configuration of claim 1, the cast-in-place concrete portion is made of concrete using blast-furnace slag cement.

[0018] The invention as recited in claim 5 is characterized in that, in addition to the configuration of claim 1, the cast-in-place concrete portion is made of concrete to which fly ash or blast furnace slag has been added.

[0019] The feature of the invention described in claim 6 is that in a method for constructing a concrete wall balustrade in which a concrete wall balustrade is erected on the side of a concrete floor slab, a plurality of anchoring steel bars are protruded from the upper surface of the side of the concrete floor slab at intervals in the direction of the bridge axis, a form unit consisting of a pair of precast embedded formwork slabs arranged at a distance from each other and a plurality of reinforcing vertical bars supported at intervals in the longitudinal direction is hung from above onto the upper surface of the side of the concrete floor slab from which the plurality of anchoring steel bars are protruded, and after the reinforcing vertical bars are installed between the anchoring steel bars, cast-in-place concrete is poured between the precast embedded formwork slabs.

[0020] The feature of the invention described in claim 7 is that, in addition to the configuration of claim 6, each of the precast embedded formwork slabs has an internal reinforcing bar having a bent convex portion bent across straight sections embedded inside the formwork slab, and the bent convex portion protrudes toward the opposing surface.

[0021] The feature of the invention described in claim 8 is that, in addition to the configuration of claim 7, the ends of the internal supports are fixed between the curved convex portions protruding from the opposing surfaces of each of the precast buried formwork slabs, and the reinforcing vertical reinforcement bodies are supported on each of the precast buried formwork slabs via the internal supports.

[0022] The invention described in claim 9 is characterized in that, in addition to the configuration of claim 6, a plurality of the formwork units are installed continuously in the bridge axis direction, and the reinforcing vertical reinforcement bodies of each formwork unit are installed between the anchoring rebars, and then concrete is poured between the precast embedded formwork slabs.

[0023] The invention as recited in claim 10 is characterized in that, in addition to the configuration of claim 6, one or more sheath tubes oriented in the bridge axis direction are pre-assembled in the formwork unit.

[0024] The invention as recited in claim 11 is characterized in that, in addition to the configuration as recited in claim 6, the cast-in-place concrete is made of blast-furnace slag cement.

[0025] The invention as set forth in claim 12 is characterized in that, in addition to the configuration as set forth in claim 6, fly ash or blast furnace slag is added to the cast-in-place concrete. Effect of the Invention

[0026] By providing the concrete wall balustrade of the present invention with the configuration described in claim 1, it becomes unnecessary to carry out stripping work at the construction site, shortening the construction period and the period of outage, while being securely integrated with the concrete floor slab. Also, a highly durable precast embedded formwork plate is placed on the surface of the wall balustrade, and the precast embedded formwork plate functions as part of the wall balustrade, so that it is possible to suppress the dissipation of moisture from the wall balustrade surface and reduce drying shrinkage, and also to suppress thermal cracks by reducing the cross-sectional thickness of the cast-in-place concrete portion and reducing temperature stress.

[0027] Furthermore, in the present invention, by providing the configuration described in claim 2, the precast embedded formwork slab and the concrete portion can be reliably integrated, and peeling and spalling of the concrete on the back surface due to collision load can be prevented.

[0028] Furthermore, in the present invention, by providing the configuration recited in claim 3, it is possible to stably connect both precast embedded form slabs and to reliably support the internal reinforcing bars between the precast embedded form slabs.

[0029] Furthermore, in the present invention, by providing the configuration recited in claim 4, it is possible to comply with green procurement and reduce the environmental load.

[0030] Furthermore, in the present invention, by providing the configuration described in claim 5, it is possible to improve durability and suppress the occurrence of initial cracks. In addition, it is expected to contribute to carbon neutrality.

[0031] By providing the method for constructing a concrete wall parapet according to the present invention with the configuration of claim 6, it becomes unnecessary to assemble rebars or remove forms at the construction site, shortening the construction period, providing a smooth working environment, and shortening the period of outage. In addition, a highly durable precast embedded formwork plate is placed on the surface of the wall parapet, and the precast embedded formwork plate functions as part of the wall parapet, so that it is possible to suppress the dissipation of moisture from the wall parapet surface and reduce drying shrinkage, and also to suppress thermal cracks by reducing the cross-sectional thickness of the cast-in-place concrete portion and reducing temperature stress.

[0032] Furthermore, in the present invention, by providing the configuration of claim 7, the precast embedded formwork slab and the concrete portion can be reliably integrated, and peeling and spalling of the concrete on the reverse side due to a collision load can be prevented.

[0033] Furthermore, in the present invention, by providing the configuration of claim 8, both precast embedded formwork slabs can be stably connected to each other, and the internal reinforcing bars can be reliably supported between the precast embedded formwork slabs.

[0034] Furthermore, in the present invention, by providing the configuration of claim 9, construction of a certain span can be efficiently carried out.

[0035] Furthermore, in the present invention, by providing the configuration of claim 10, the work of installing a sheath pipe for laying a communication cable or the like at the construction site can be omitted, and the construction period can be shortened.

[0036] Furthermore, in the present invention, by incorporating the configuration of claim 11, it is possible to comply with green procurement and reduce the environmental load.

[0037] In addition, in the present invention, by providing the configuration of claim 12, it is possible to improve durability and suppress the occurrence of initial cracks. In addition, it is expected to contribute to carbon neutrality. [Brief description of the drawings]

[0038] [Figure 1] FIG. 2(a) is a front view showing an example of a road using a concrete wall parapet according to the present invention, and FIG. 2(b) is a longitudinal sectional view of the same. [Diagram 2] FIG. 2 is a front view of the above concrete wall balustrade. [Diagram 3] FIG. [Figure 4] FIG. 2 is a partially enlarged cross-sectional view of the precast embedded formwork plate of the same. [Diagram 5] FIG. 2 is an exploded perspective view showing the reinforcing vertical bars of the same. [Figure 6] 4(a) to 4(e) are vertical cross-sectional views showing variations of the anchoring reinforcement bars of the same embodiment. [Figure 7] FIG. 2 is a vertical cross-sectional view showing a state of a reinforcing bar cage assembly process in the method for constructing a concrete wall balustrade according to the present invention. [Figure 8] FIG. 4 is a vertical cross-sectional view showing the form unit assembly process of the above. [Figure 9] FIG. 2 is a front view showing the state in which the fixing steel bar is installed. [Figure 10] FIG. [Figure 11] FIG. 4 is a front view showing the formwork unit installation process of the above. [Figure 12] FIG. [Figure 13] FIG. 4 is a vertical cross-sectional view showing the above-mentioned formwork unit installed. [Figure 14] This is a front view showing the situation when the above-mentioned formwork units are connected in the bridge axis direction. [Figure 15] 1 is a graph showing the results of a static load test performed on a concrete wall balustrade according to the present invention and a conventional construction method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Next, an embodiment of the concrete wall parapet according to the present invention will be described based on the examples shown in Figures 1 to 6. In the figures, reference numeral 1 denotes a road such as a bridge or an elevated road.

[0040] As shown in Figure 1, this road 1 comprises a number of bridge piers 2, 2 erected at intervals on the ground, a bridge girder 3 erected between the piers 2, 2, and a concrete deck 4 supported by the bridge girder 3. On both sides of the concrete deck 4, there are erected concrete wall parapets 5 made of reinforced concrete that run continuously in the bridge axis direction for the purposes of preventing vehicles from falling or straying from the road, guiding the view, etc.

[0041] The concrete deck 4 is not particularly limited, but may have a structure in which a plurality of precast deck members made of precast concrete are arranged in series in the bridge axis direction on a bridge girder.

[0042] As shown in Figures 2 and 3, the concrete wall parapet 5 comprises a pair of precast embedded formwork slabs 6, 7 arranged at intervals from each other in the wall thickness direction on the sides of the concrete floor slab 4, anchored reinforcing bars 8, 8... protruding from the top surface of the concrete floor slab 4 between the precast embedded formwork slabs 6, 7 and installed at intervals in the bridge axis direction, a reinforcing bar cage 9 arranged between the precast embedded formwork slabs 6, 7, and a cast-in-place concrete section 10 poured between the precast embedded formwork slabs 6, 7, and the anchored reinforcing bars 8, 8... and the reinforcing bar cage 9 are connected by a lap joint structure or the like to be integrated with the concrete floor slab 4.

[0043] In addition, in this concrete wall parapet 5, a plurality of sheath pipes 27, 27... continuing in the bridge axis direction for laying communication cables etc. are embedded in parallel in the cast-in-place concrete part 10 between the precast embedded formworks 6, 7 at intervals in the height direction. Note that there may be only one sheath pipe 27.

[0044] The precast embedded formwork slabs 6, 7 consist of an inner precast embedded formwork slab (hereinafter referred to as the inner PCa slab 6) that is placed on the center of the road, and an outer precast embedded formwork slab (hereinafter referred to as the outer PCa slab 7) that is placed on the outside of the road, and the inner PCa slab 6 and the outer PCa slab 7 are installed at the side end of the concrete deck slab 4 in an opposing arrangement with a gap between them in the width direction of the bridge.

[0045] The inner and outer PCa panels 6 and 7 are made of reinforced concrete using high-strength mortar with a water-to-binder ratio of 30% or less as the base material, and are each formed to a thickness of approximately 30 to 40 mm.

[0046] The inner PCa panel 6 is formed like a stepped inclined plate and includes a band-shaped lower wall portion 6c that is raised vertically from the installation surface, a step inclined portion 6b that is inclined at a predetermined angle from the upper end of the lower wall portion 6c, and an upper wall portion 6a that rises at a gradual incline from the upper end of the step inclined portion 6b.

[0047] This inner PCa panel 6 is continuous along the lower wall portion 6c, the step inclined portion 6b and the upper wall portion 6a, and is embedded in a lattice pattern with a number of vertical bars for the buried formwork 11, 11... arranged at intervals in the bridge axis direction (length direction of the panel), and horizontal bars for the buried formwork 12, 13 arranged at intervals along the vertical bars for the buried formwork 11, 11... and continuing along a direction intersecting the vertical bars for the buried formwork 11, 11... (length direction of the panel), forming the internal reinforcing bars of the reinforced concrete structure.

[0048] Furthermore, as shown in Figures 3 and 4, instead of normal straight rebars, the buried formwork cross bars 13 that are placed at a specified height are made of stainless steel internal rebars having bent convex portions 13a, 13a... that are bent across the straight sections embedded inside the formwork, and the top side of each of the bent convex portions 13a, 13a... protrudes from the surface of the opposing face.

[0049] The external PCa panel 7 is formed in a rectangular plate shape, raised vertically from the installation surface, and made of stainless steel reinforcement with embedded vertical reinforcements 11, 11... for the buried formwork and horizontal reinforcements 12, 13 for the buried formwork arranged in a grid pattern at intervals both vertically and horizontally.

[0050] In addition, for the embedded formwork horizontal bars 13 that are arranged at a predetermined height, i.e., at the same height as the embedded formwork rebars 13 of the inner PCa panel 6, as shown in Figures 3 and 4, instead of normal straight rebars, stainless steel internal rebars are used having bent convex portions 13a, 13a... that are bent across the straight sections embedded inside the formwork panel, and the top side of each of the bent convex portions 13a, 13a... protrudes from the surface of the opposing face.

[0051] Between the opposing inner PCa plate 6 and outer PCa plate 7, a number of internal supports 14, 14..., whose ends are fixed to the curved convex portions 13a, 13a... protruding toward the opposing surface, are supported across the inner and outer PCa plates 6, 7.

[0052] In addition, a plurality of shape-retaining members (not shown) made of separators, shaped steel, etc. are bridged between the opposing inner PCa panel 6 and outer PCa panel 7.

[0053] The inner and outer PCa panels 6, 7 can support each other and stand on their own via these multiple shape-retaining members and internal supports 14, 14..., and the reinforcing bar cage 9 is supported inside via the shape-retaining members and internal supports 14, 14..., so that the inner and outer PCa panels 6, 7 and the reinforcing bar cage 9 are integrated as a formwork unit 15 via the internal supports 14, 14....

[0054] The reinforcing bar cage 9 comprises reinforcing vertical bars 20, 20... arranged at intervals in the bridge axis direction and connected to the anchor bars 8, 8... with lap joints, and a number of cross bars 21, 21... supported across the reinforcing vertical bars 20, 20... in the bridge axis direction.

[0055] As shown in FIG. 5, the reinforcing vertical reinforcement bodies 20, 20... comprise vertical reinforcement members 22 consisting of inner vertical reinforcement members 22a and outer vertical reinforcement members 22b arranged at intervals in the wall thickness direction, and reinforcing bars 23 having diagonal reinforcement portions 23b supported across the inner vertical reinforcement members 22a and the outer vertical reinforcement members 22b.

[0056] The vertical reinforcement member 22 is integrally formed from a bar material made of steel such as SD345, and the upper end of the inner vertical reinforcement 22a and the upper end of the outer vertical reinforcement 22b are connected by a connecting portion 22c.

[0057] In the construction area, which has a span between the piers, the vertical reinforcement members 22 used are 16 mm in diameter within a 1 m range at the ends of the construction area, and 13 mm in diameter for other general parts.

[0058] In addition, the vertical reinforcement members 22 are arranged so that their lower ends are at approximately the same height as the lower ends of the inner and outer PCa panels 6, 7 and their upper ends are at a certain distance lower than the upper ends of the inner and outer PCa panels 6, 7, and the inner vertical reinforcement members 22a and outer vertical reinforcement members 22b are each arranged at a certain distance (cover) from the opposing inner and outer PCa panels 6, 7.

[0059] The reinforcing bars 23 are made of rods of the same diameter as the vertical reinforcing bars 22, that is, in the construction area where the piers form one span, thicker ones with a diameter of 16 mm are used at the ends of the construction area, i.e., within 1 m from the construction area, and ones with a diameter of 13 mm are used for other general parts, and are equipped with upper vertical bars 23a extending vertically, diagonal bars 23b extending diagonally downward from the upper vertical bars 23a, and lower vertical bars 23c extending downward from the lower ends of diagonal bars 23b.

[0060] The reinforcing bars 23 are tied together with the upper vertical bars 23a overlapping the outer vertical bars 22b, and the diagonal bars 23b are supported across the inner vertical bars 22a and the outer vertical bars 22b.

[0061] The horizontal bars 21, 21... are made of typical rod-shaped reinforcing bars, and are tied and fixed to the inner vertical bars 22a and the outer vertical bars 22b at intervals in the up-down direction.

[0062] In addition, the vertical spacing of the horizontal bars 21, 21... is such that those on the upper side are densely reinforced, i.e., the spacing between the horizontal bars is narrow, and those on the lower side are loosely reinforced, i.e., the spacing between the horizontal bars is wide.

[0063] Incidentally, one or more sheath tubes 27, 27... for laying communication cables or the like are arranged within the reinforcing bar cage 9 as required, and are fixed to the reinforcing bar cage 9 via supporting reinforcing bars (not shown).

[0064] As shown in Figures 2 and 3, the anchoring steel bars 8, 8... are formed as a single unit from a single bar of high-tensile steel such as SD490, with their lower ends embedded in the concrete deck 4. They comprise inner and outer anchoring vertical bars 8a, 8b that protrude from the upper surface of the concrete deck 4 at intervals in the width direction of the bridge, and anchoring diagonal bars 8c that are suspended between the upper ends of the inner and outer anchoring vertical bars 8a, 8b. This structure allows the inner and outer anchoring vertical bars 8a, 8b to bear the tension when the load acts on the concrete wall parapet 5 from the roadway side (inside), and also allows the inner and outer anchoring vertical bars 8a, 8b to bear the tension when the load acts from the outside.

[0065] Furthermore, by using high tensile steel such as SD490 for the anchoring rebars 8, 8..., it is possible to use rebars with a smaller diameter (diameter 13 mm) compared to when steel materials such as SD345 are used (diameter 16 mm), thereby avoiding dense spacing between the rebars.

[0066] These fixing bars 8, 8... are inserted between the reinforcing vertical bars 20, 20, and are arranged so that the outer fixing vertical bars 8a overlap with the outer vertical bars 22b, the fixing diagonal bars 8c overlap with the diagonal bars 23b of the reinforcing bars 23, and the inner fixing vertical bars 8b overlap with the lower vertical bars 23c of the reinforcing bars 23, thereby forming lap joints with the reinforcing vertical bars 20, 20...

[0067] The configuration of the fixed reinforcing bars 8, 8... is not limited to the above-mentioned embodiments, and may be, for example, two rows of loop-shaped reinforcing bars 24, 24 (closed type) as shown in Figure 6(a), a plurality of reinforcing bars 25, 25... having enlarged diameter portions 25a at their heads that overlap with the inner and outer vertical bars 22a, 22b and the diagonal bar portion 23b as shown in Figure 6(b) and mechanically fixed to the cast-in-place concrete portion 10 (mechanical fixing type), a combination of closed type 24 and mechanical fixing type 25 as shown in Figure 6(c) (composite type), a combination of reinforcing bar 26 having a hook portion 26a at its tip and closed type 24 as shown in Figure 6(d) (hook combination type), or a single row of loop-shaped reinforcing bars 28 (closed type) as shown in Figure 6(e).

[0068] The cast-in-place concrete section 10 is not particularly limited, but for civil engineering concrete, type B blast-furnace cement is generally used as the cement in accordance with green procurement from the perspective of reducing the environmental impact, and blast-furnace cement containing type B blast-furnace cement can be used for the cast-in-place concrete section 10.

[0069] Furthermore, the cast-in-place concrete portion 10 may use fly ash cement or blast furnace slag cement as the cement.

[0070] When fly ash cement is used, the concrete develops its strength slowly, but the strength increases over the long term, durability improves, and the rate of temperature rise is reduced, making initial cracks less likely to occur.

[0071] Furthermore, the use of fly ash and other materials as substitutes for cement and fine aggregate is expected to contribute to carbon neutrality.

[0072] Next, a method for constructing this concrete wall parapet 5 will be described based on the embodiment shown in FIG. 2 and FIGS.

[0073] First, as a preliminary preparation, the formwork unit 15 is assembled in a factory or the like.

[0074] As shown in Figure 7, the formwork unit 15 is assembled by arranging multiple vertical reinforcement members 22 at intervals on a flat assembly stand 30 (workbench), supporting multiple horizontal reinforcement members 21, 21... facing the bridge axis direction by straddling adjacent inner and outer vertical reinforcement members 22a, 22b in the bridge axis direction, and placing reinforcing bars 23 on the sides of the vertical reinforcement members 22 to form reinforcing vertical reinforcement bodies 20, 20.... The vertical reinforcement members 22, reinforcing bars 23 and horizontal reinforcement members 21, 21... are then tied and fixed together to assemble the reinforcing bar cage 9.

[0075] Next, on the assembly stand 30, as shown in Figure 8, the inner PCa plate 6 and the outer PCa plate 7 are erected on both sides of the reinforcing bar cage 9, and the ends of the internal supports 14, 14... are fixed to the curved convex portions 13a, 13a... that protrude toward the opposing surfaces between the opposing inner PCa plate 6 and outer PCa plate 7, so that the inner PCa plate 6 and outer PCa plate 7 are supported by each other via the internal supports 14, 14...

[0076] Then, the inner supports 14, 14 . . . are connected to the reinforcing bar cage 9 to support the reinforcing bar cage 9 on the inner and outer PCa panels 6, 7, and shape-retaining members (not shown) are attached to assemble the formwork unit 15.

[0077] In addition, if necessary, supporting steel bars (not shown) are erected between the inner PCa panel 6 and the outer PCa panel 7 at a specified height, and multiple sheath tubes 27, 27 facing in the bridge axis direction are arranged in parallel within the reinforcing bar cage 9 via the supporting steel bars, and the sheath tubes 27, 27... are incorporated into the formwork unit 15 in advance.

[0078] In the above embodiment, the reinforcing bar cage 9 and formwork unit 15 are assembled in a vertical position on the assembly stand 30 (workbench). However, the assembly work of the reinforcing bar cage 9 and formwork unit 15, although not specifically shown, may be performed by assembling the reinforcing bar cage 9 separately and assembling and installing the inner PCa plate 6 and the outer PCa plate 7 in a horizontal position with the outer PCa plate 7 facing down on the assembly stand 30, and then inserting the reinforcing bar cage 9 between the inner PCa plate 6 and the outer PCa plate 7 to assemble them firmly.

[0079] Meanwhile, at the construction site, as shown in Figs. 9 and 10, a large number of anchoring rebars 8, 8 . . . are installed on the concrete deck 4 at predetermined intervals in the bridge axis direction.

[0080] The anchoring steel bars 8, 8... can be embedded in advance when manufacturing the precast concrete deck components that make up the concrete deck slab 4, and then positioned at a predetermined interval in the bridge axis direction on the concrete deck slab 4 by installing the precast concrete deck components, or the embedding work can be performed on the construction site in the existing concrete deck slab 4.

[0081] Next, the formwork unit 15, which has been preassembled at a factory or the like, is transported to the construction site and, as shown in Figures 11 and 12, is lifted by a crane or the like and moved above the side of the concrete deck 4. The reinforcing vertical bars 20, 20... are positioned between the anchoring bars 8, 8 installed at intervals in the bridge axis direction, and the anchoring bars 8, 8... are positioned so that they are contained between the inner and outer PCa panels 6, 7 (formwork unit lifting work).

[0082] Then, once the alignment is complete, as shown in Figure 13, the formwork unit 15 is lowered while making fine adjustments to its position, placed on the upper side surface of the concrete floor slab 4, and fixed onto the concrete floor slab 4 (formwork unit installation work).

[0083] As shown in FIG. 14, the lifting and installation work of the form units 15 is repeated for the construction span, so that the form units 15 are successively installed in the bridge axis direction.

[0084] In this case, when sheath tubes 27, 27... are arranged in the formwork units 15 connected in the bridge axis direction, the end tubes of each sheath tube 27, 27 that are continuous in the bridge axis direction are connected.

[0085] Once the installation of the formwork unit 15 is complete, as shown in Fig. 3, concrete containing blast-furnace cement type B or fly ash is poured into the formwork unit 15, i.e., between the inner and outer PCa panels 6, 7, and the concrete filled between the inner and outer PCa panels 6, 7 forms the cast-in-place concrete section 10. The formwork unit 15 has the function of curing the poured concrete, making it possible to omit the curing work required in conventional construction methods.

[0086] Finally, the concrete constituting the cast-in-place concrete portion 10 is hardened to construct the concrete wall balustrade 5 for the specified construction span.

[0087] The above-mentioned work is then repeated for each construction span to construct a continuous concrete wall parapet 5 in the bridge axial direction.

[0088] In the concrete wall railing 5 constructed in this manner, the fixed reinforcing bars 8, 8... fixed to the concrete floor slab 4 and the reinforcing bar cages 9 incorporated into the formwork unit 15, more specifically the reinforcing vertical bars 20, 20... are connected by a lap joint structure or the like, thereby integrating the wall railing and the concrete floor slab 4 and creating a structure that can withstand collision loads.

[0089] FIG. 15 is a graph showing the results of a static loading test conducted on concrete wall parapets produced by the present invention and the conventional method, to verify their stress resistance performance based on the design load of the SS type concrete wall parapet (vehicle safety fence) (collision load of 138 kN). It was confirmed that while the maximum load of the concrete wall parapet produced by the conventional method was 186 kN (1.35 times the design load), the concrete wall parapet 5 produced by the present invention had a maximum load of 265 kN (1.92 times the design load), demonstrating excellent stress resistance performance.

[0090] Furthermore, this concrete wall railing 5 uses formwork units 15 that are lighter than precast components for conventional wall railings (for example, approximately 1.8 to 2.3 t for 2.5 m in the bridge axis direction), so the work of lifting and setting up the formwork units 15 can be carried out efficiently, thereby shortening the construction period.

[0091] Furthermore, with this concrete wall parapet 5, the formwork units 15 are stably installed on the concrete floor slab 4, and the inner and outer PCa panels 6, 7 are not removed but form the inner and outer surfaces of the wall parapet as is, so that even during the period until the concrete hardens, the road can be opened and other work can be carried out, thereby shortening the construction period.

[0092] Furthermore, highly durable precast embedded formwork slabs 6, 7 are placed on the surface of the wall parapet and function as part of the wall parapet, so that it is possible to suppress the loss of moisture from the surface of the wall parapet and reduce drying shrinkage, while also reducing the cross-sectional thickness of the cast-in-place concrete section and suppressing thermal cracks due to reduced temperature stress, thereby improving the durability of the entire wall parapet.

[0093] In particular, when concrete containing added fly ash is used for cast-in-place concrete, there is an issue that it takes time for the concrete to develop strength. However, with the present invention, as described above, it is possible to keep the road in service and to carry out other work even during the period until the concrete hardens.

[0094] Therefore, in the present invention, when concrete containing added fly ash is used, the above problems do not become a problem, and moreover, durability is improved by increasing the strength over a long period of time, and the rate of temperature rise can be suppressed, making initial cracks less likely to occur. In addition, the effective use of fly ash is expected to contribute to carbon neutrality. Furthermore, since precast embedded formwork slabs use high-strength mortar with a water-to-binding material ratio of 30% or less, a long life for the wall parapet can be achieved.

[0095] Furthermore, by previously assembling the sheath pipes 27, 27... in the formwork unit 15 at a factory or the like, the work of installing the sheath pipes 27, 27... on-site can be omitted, and the construction period can be shortened.

[0096] In the above-mentioned embodiment, specific diameters of the anchoring bars 8, the vertical reinforcement members 22 and the reinforcing bars 23 have been given as examples, but it goes without saying that the dimensions, including the diameters, of all the members including these members can be freely selected based on the design, etc. [Explanation of symbols]

[0097] 1 road 2. Bridge Pier 3 Bridge girders 4 Concrete deck 5 Concrete wall parapet 6 Inner PCa plate (precast embedded formwork plate) 7 External PCa plate (precast embedded formwork plate) 8 Anchorage rebar 9. Reinforced Concrete Cage 10 Cast-in-place concrete section 11 Vertical reinforcement for buried formwork 12 Horizontal reinforcement for embedded formwork 13 Horizontal reinforcement for embedded formwork 14 Internal Support 15 Formwork Unit 20 Reinforcement vertical bars 21 Horizontal Stripes 22 Vertical reinforcement members 23 Reinforcement 24 Reinforced Concrete (Closed Type) 25 Reinforced concrete (mechanical fixing) 26 Reinforced concrete (hook type) 27 Sheath tube 28 Reinforced concrete (loop)

Claims

1. In a concrete wall parapet erected on the side of a concrete floor slab, The bridge comprises a pair of precast embedded formwork slabs arranged at intervals in the wall thickness direction on the sides of the concrete slab, anchoring steel bars protruding from the upper surface of the concrete slab between the precast embedded formwork slabs and installed at intervals in the bridge axis direction, reinforcing vertical bars arranged at intervals in the bridge axis direction between the precast embedded formwork slabs and connected to the anchoring steel bars, a plurality of horizontal bars supported across the reinforcing vertical bars in the bridge axis direction, and a cast-in-place concrete section poured between the precast embedded formwork, The reinforcing vertical reinforcement body comprises a vertical reinforcement section consisting of inner vertical reinforcement and outer vertical reinforcement arranged at intervals in the wall thickness direction, and a reinforcing bar having a diagonal reinforcement section supported across the inner vertical reinforcement and the outer vertical reinforcement, and the vertical reinforcement section and the reinforcing bar are connected to the anchoring steel.

2. The concrete wall balustrade described in claim 1, wherein each of the precast embedded formwork slabs has an internal reinforcing bar having a bent convex portion bent across straight sections embedded inside the formwork slab, and the bent convex portion protrudes toward the opposing surface.

3. An internal support structure is provided, the end of which is fixed to the bent convex portion protruding toward the opposing surface side of the opposing precast embedded form slabs, and the internal support structure is supported across the precast embedded form slabs, 3. A concrete wall parapet according to claim 2, wherein the reinforcing vertical bars are supported on the precast embedded formwork via the internal supports.

4. 2. The concrete wall balustrade according to claim 1, wherein the cast-in-place concrete portion is made of concrete using blast furnace cement.

5. 2. The concrete wall balustrade according to claim 1, wherein the cast-in-place concrete portion is made of concrete containing fly ash or blast furnace slag.

6. A method for constructing a concrete wall balustrade by erecting a concrete wall balustrade on the side of a concrete floor slab, comprising: A plurality of anchoring rebars are provided protrudingly at intervals in the bridge axis direction on the side upper surface of the concrete deck, A form unit is hung from above, which is made up of a pair of precast embedded formwork slabs arranged at intervals from each other and a plurality of reinforcing vertical bars supported at intervals in the longitudinal direction, on the upper side surface of the concrete floor slab on which the plurality of anchoring bars are protruding, and the reinforcing vertical bars are installed between the anchoring bars. A method for constructing a concrete wall parapet, comprising pouring cast-in-place concrete between the precast embedded formwork slabs.

7. The method for constructing a concrete wall balustrade as described in claim 6, wherein each of the precast embedded formwork panels has an internal reinforcing bar having a bent convex portion bent across straight sections embedded inside the formwork panel, and the bent convex portion protrudes toward the opposing surface.

8. A method for constructing a concrete wall balustrade as described in claim 7, wherein ends of internal supports are fixed between the bent convex portions protruding from the opposing surfaces of each of the precast buried formworks, and the reinforcing vertical reinforcement members are supported by each of the precast buried formworks via the internal supports.

9. 7. A method for constructing a concrete wall parapet as described in claim 6, further comprising the steps of: installing a plurality of said formwork units in succession in the bridge axis direction; installing the reinforcing vertical bars of each of said formwork units between said anchoring bars; and then pouring concrete between said precast embedded formwork slabs.

10. 7. A method for constructing a concrete wall balustrade according to claim 6, wherein one or more sheath pipes oriented in the bridge axial direction are pre-assembled into the formwork unit.

11. 7. The method for constructing a concrete wall balustrade according to claim 6, wherein the cast-in-place concrete is made of blast furnace cement.

12. 7. The method for constructing a concrete wall balustrade according to claim 6, wherein the cast-in-place concrete is added with fly ash or blast furnace slag.

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