Anchoring structure between non-ferrous reinforcing bar of cast-in-place wall balustrade and floor slab

Abstract

To provide an anchoring structure between a non-ferrous reinforcement of a cast-in-place wall balustrade and a floor slab, which has required shear resistance at a joint portion, which prevents stress from concentrating on a bent portion, and which achieves dynamically efficient bar arrangement.SOLUTION: In an anchoring structure between a non-ferrous reinforcement of a cast-in-place wall balustrade 2 and a floor slab (PC floor slab 2), the non-ferrous reinforcement has a diameter equal to or larger than a nominal diameter of a reinforcing bar required in structural design, a bending inner radius of the non-ferrous reinforcement is 2.5 times or more of the bending inner radius of the reinforcing bar, and an anchoring length of the non-ferrous reinforcement is 12 times or more of a diameter of the non-ferrous reinforcement.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fixing structure between non-steel reinforcement bars of a cast-in-place wall parapet and a deck slab. [Background technology]

[0002] In recent years, there has been a demand for higher durability in PC deck slabs. To this end, designs to ensure durability have been developed, and materials that achieve high durability (such as coated strands and stainless steel) are becoming more widespread. The main causes of deterioration of existing RC deck slabs are concrete fatigue and salt damage. Therefore, as a fundamental countermeasure against salt damage, PC deck slab structures made of non-corrosive materials have been proposed, and CFCC Slabs (registered trademark) and MeL Slabs (registered trademark) have been developed, in which carbon fiber composite cables are placed as tension members in two directions: perpendicular to the bridge axis and in the bridge axis direction.

[0003] Slabs with bidirectional carbon fiber composite cables, such as CFCC Slabs (registered trademark) and MeL Slabs (registered trademark), are expected to be used in severe salt damage environments because they ensure durability and reduce life cycle costs (LCC). As mentioned above, it's easy to imagine that PC components made of non-steel reinforcement, such as carbon fiber composite cables, are highly durable. However, because MeL Slabs (registered trademark) are PC decks, the accompanying parapets must also be durable. For example, if only the parapets were constructed using steel, their durability would be limited by exposure to antifreeze and salt damage. This would require the joints between the parapets and PC deck to be removed and replaced with new members, which would result in the loss of prestress in the PC deck.

[0004] Furthermore, if the wall parapet were to be cut horizontally along the line of the top edge of the PC deck and new wall parapets constructed using anchors, the remaining steel in the PC deck would corrode, potentially causing cracks due to expansion pressure caused by corrosive organisms. Given these factors, it is considered necessary to construct even the wall parapet components using non-ferrous materials from a durability perspective. Furthermore, wall parapets, with their traditional Florida-type design, have long been used and are a highly reliable and proven structure. While it would be ideal to simply replace the existing reinforcing bars with non-ferrous materials, consideration is needed to address issues not previously understood with existing technology, such as shear resistance. Therefore, the development of a structure to anchor the non-ferrous reinforcing bars in the wall parapet to the deck is desirable.

[0005] For example, Patent Document 1 describes a precast wall balustrade in which a precast wall balustrade and a precast deck slab are connected under tension with tendons, and that the tendons may be made of rust-resistant continuous fiber reinforcement material made of carbon fiber impregnated with a thermosetting resin (see claims 1 and 2 of Patent Document 1, paragraphs

[0009] to

[0027] of the specification, Figures 1 to 5 of the drawings, etc.).

[0006] Furthermore, Patent Document 2 describes a precast wall balustrade in which the precast wall balustrade and the deck slab are fixed with fixing bars, and the fixing bars are made of glass fiber-reinforced, rust-resistant fiber-reinforced plastic (see claims 1 and 2 of Patent Document 2, paragraphs

[0009] to

[0029] of the specification, and Figures 1 to 3 of the drawings, etc.).

[0007] Furthermore, Patent Document 3 discloses a method for installing a road bridge guardrail, which includes the steps of erecting continuous fiber reinforcement material on the side edge of a deck slab, installing a precast wall material on the side edge of the deck slab while inserting the continuous fiber reinforcement material into a through hole of the precast wall material that is capable of accommodating the continuous fiber reinforcement material and has an uneven surface on its inner wall to improve adhesion of a cement-based filler, and filling the gaps in the through hole with the cement-based filler (see claims 1 and 2 of Patent Document 3, paragraphs

[0021] to

[0045] of the specification, Figures 1 to 7 of the drawings, etc.).

[0008] However, the wall balustrades described in Patent Documents 1 to 3 are all precast wall balustrades, and the arrangement of anchoring reinforcement does not take into account the characteristics of continuous fiber reinforcement made of carbon fiber, which has high tensile strength but is weak against shear force, and there is a problem that they cannot be applied to cast-in-place wall balustrades.

[0009] Furthermore, Patent Document 4 describes a cast-in-place balustrade in which a self-supporting three-dimensional knitted fabric, made by weaving fiber bundles with knots at a pitch of 5 to 500 mm in three-dimensional directions of the X-axis, Y-axis, and Z-axis, is embedded in balustrade concrete, and the three-dimensional knitted fabric in the balustrade is engaged with a part of the reinforcing bars in the deck slab (see Claims 1 and 2 of Patent Document 4, line 20 from the top in the left column on page 3 to line 8 from the bottom in the right column on page 3 of the specification, Figures 4 to 8 of the drawings, etc.).

[0010] However, the cast-in-place wall parapet described in Patent Document 4 simply replaces the conventional reinforcing bars used as anchoring reinforcement with fiber bundles such as aramid fiber, and does not take into consideration shear resistance at all. As a result, the cast-in-place wall parapet described in Patent Document 4 does not have reinforcement (arrangement) that is appropriate for the characteristics of continuous fiber reinforcement, which is a non-ferrous metal, and has the problem of being over-designed and inefficient. In particular, when carbon fiber composite cables are used as anchoring reinforcement, stress concentrates at the bent parts, causing breakage at the bent parts at a stage lower than the guaranteed load. There is a strong demand for an anchoring structure with the deck slab that can solve this problem. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent Publication No. 2021-195744 [Patent Document 2] Patent No. 7129440 [Patent Document 3] Patent No. 6370729 [Patent Document 4] Special Publication No. 8-14091 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention was devised in view of the above-mentioned problems, and its purpose is to provide an anchoring structure between the non-steel reinforcing bars of a cast-in-place wall parapet and the deck slab, which has the necessary shear resistance and does not cause stress to concentrate in the bent parts, resulting in a mechanically efficient reinforcement arrangement. [Means for solving the problem]

[0013] The anchoring structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab according to the first invention is an anchoring structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab, characterized in that the non-steel reinforcement bars have a diameter equal to or greater than the nominal diameter of the reinforcing bars required in the structural design, the inner bending radius of the non-steel reinforcement bars is 2.5 times or more the inner bending radius of the reinforcing bars, and the anchoring length of the non-steel reinforcement bars is 12 times or more the diameter.

[0014] The second invention relates to the fixing structure between the non-ferrous reinforcement bars of a cast-in-place wall parapet and the deck slab, and is characterized in that, in the first invention, the non-ferrous reinforcement bars are made of a composite of resin and resin fiber, and are stranded carbon fiber reinforcement materials with unevenness formed on each outer peripheral wire.

[0015] The third invention relates to a fixing structure between the non-steel reinforcing bars of a cast-in-place wall parapet and the deck slab, and is characterized in that, in the first invention, the deck slab is a precast deck reinforced with non-steel reinforcing bars, and the non-steel reinforcing bars provided at the joint with the wall parapet that protrudes from the ground covering part of the precast deck slab are loop bars.

[0016] The fourth invention relates to the anchoring structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab, which is the third invention, characterized in that the precast deck slab is a PC deck slab to which prestressing has been applied in advance in two directions by carbon fiber composite cables.

[0017] The fifth invention relates to the anchoring structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab, which is the fourth invention, characterized in that the PC deck slab is made of short-fiber reinforced concrete mixed with organic short fibers.

[0018] The sixth invention relates to the fixing structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab, which is the third invention, and is characterized in that a step is provided in the ground covering portion of the precast deck slab as a shear key.

[0019] The seventh invention relates to an anchoring structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab, and is characterized in that in the sixth invention, the non-steel reinforcement bars are arranged such that the shear load acting on the wall parapet is set based on the applied load obtained by applying an impact strength 10 times the design load to an RC wall parapet reinforced with steel bars.

[0020] The eighth invention relates to the fixing structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab, which is the seventh invention, and is characterized in that a lattice-shaped CFRP grid is arranged in the ground covering part of the precast deck slab as shear reinforcement. [Effects of the Invention]

[0021] According to the first to eighth inventions, a fixing structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab is provided, which has the necessary shear resistance at the joints and does not cause stress concentration at the bent parts, resulting in a mechanically efficient reinforcement arrangement, and it is possible to significantly improve the durability of the entire structure without the risk of rust. Also, while reinforcing bars that have been treated with rust prevention measures such as epoxy resin coating are generally used to prevent corrosion due to salt damage during on-site work, according to the first to eighth inventions, since non-steel reinforcement bars are used, rust prevention measures such as epoxy resin coating are not necessary.

[0022] In particular, according to the second invention, unevenness is formed on the surface of the non-steel reinforcing bars, improving their adhesion to concrete, and allowing the non-steel reinforcing bars to exhibit anchorage performance equal to or better than that of ordinary steel bars.

[0023] In particular, according to the third invention, the non-ferrous reinforcement bars installed at the joints between the wall parapets and the ground covering portion of the precast deck slab are loop reinforcement bars, which minimizes the storage space required within the precast factory and makes it possible to make the protruding non-ferrous reinforcement bars less likely to break and more resistant to deformation when subjected to the forces that occur during transportation and erection.

[0024] In particular, according to the fourth invention, prestress is applied in two directions in advance, so it is expected that the shear strength will be improved by the prestress introduced into the foundation section by the non-steel reinforcing bars arranged in the bridge axis direction of the PC deck slab.

[0025] In particular, according to the fifth aspect of the invention, since the concrete is made of short fiber reinforced concrete, it is possible to eliminate the need for reinforcing bars other than the non-ferrous cables of the tendons that introduce prestress.

[0026] In particular, according to the sixth and seventh inventions, a concrete shear key is provided, so that the shear load acting on the wall parapet can be set and satisfied based on the applied load obtained by applying an impact strength 10 times the design load to an RC wall parapet reinforced with steel bars.

[0027] In particular, according to the eighth invention, a CFRP grid is arranged, so that the CFRP grid can resist the shear force acting on the joint between the cast-in-place wall parapet and the precast deck slab, thereby improving shear resistance. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a vertical cross-sectional view showing the configuration of the central part of a fixing structure 1 according to an embodiment of the present invention. [Figure 2] Figure 2 is a photograph showing the uneven shape of a carbon fiber reinforcement bar for RC. [Figure 3] Figure 3 shows the individual non-steel reinforcing bars arranged in the balustrade section (wall balustrade 3) of the anchorage structure 1, where (a) shows the upper bar WL3-U, (b) shows the lower bar WL3-L, and (c) shows the cross-sectional diagonal bar WL4. [Figure 4] Figure 4 shows the non-steel reinforcing bars arranged at the joints and ground cover sections of the anchorage structure 1, where (a) shows the first loop reinforcement ML-1 at the joint section, (b) shows the second loop reinforcement ML-2 at the joint section, and (c) shows the ground cover reinforcement ML-3. [Figure 5] Figure 5 is a photograph showing the diagonal cracks that occurred over an 800 mm stretch of ground cover when there was no reinforcement material. [Figure 6] Figure 6 is a photograph showing the diagonal cracks that occurred over a 600 mm stretch of ground cover when no reinforcement material was used. [Figure 7] Figure 7 shows the standard part of the test specimen, where (a) is a vertical cross-sectional view, (b) is a side view seen from the side opposite the impact surface, and (c) is a side view seen from the impact surface side. [Figure 8] Figure 8 shows the end of the test specimen, where (a) is a vertical cross-sectional view, (b) is a side view seen from the opposite side of the impact surface, and (c) is a side view seen from the impact surface side. [Figure 9] Figure 9 is a photograph showing the reinforcement arrangement of the test specimen in the standard section deck slab. [Figure 10] Figure 10 is a photograph showing the reinforcement arrangement of the specimen in the standard wall parapet. [Figure 11]Figure 11 is a photograph showing the reinforcement arrangement of the specimen at the end deck slab. [Figure 12] Figure 12 is a photograph showing the reinforcement arrangement of the specimen in the end wall parapet. [Figure 13] Figure 13 is a photograph showing the completed standard section specimen. [Figure 14] Figure 14 is a photograph showing the completed end specimen. [Figure 15] FIG. 15 shows a crash test device, where (a) is a side view, (b) is a plan view, and (c) is a front view seen from the direction of impact of the weight. [Figure 16] FIG. 16 shows the results of a frontal collision test when the central part of the wall parapet is loaded with a load equivalent to the design load. [Figure 17] FIG. 17 shows the results of a rear-side collision test when the central part of the wall parapet is loaded with a load equivalent to the design load. [Figure 18] FIG. 18 is a photograph showing the test specimen after loading equivalent to the design load. [Figure 19] FIG. 19 shows the results of a frontal collision test when a load equivalent to the bearing strength of the central part of the wall parapet is applied. [Figure 20] FIG. 20 shows the results of a rear-side collision test when a load equivalent to the bearing strength of the central part of the wall parapet is applied. [Figure 21] FIG. 21 is a photograph showing the condition of the loading surface side (front side) of the test specimen after loading equivalent to the bearing capacity of the cast-in-place wall parapet. [Figure 22] FIG. 22 is a photograph showing the condition of the opposite side (back side) of the specimen after loading equivalent to the bearing capacity of the cast-in-place wall parapet. [Figure 23] Figure 23 is a crack diagram showing cracks on the specimen after loading equivalent to the strength of the cast-in-place wall parapet. [Figure 24] FIG. 24 shows the results of a frontal collision test when the wall parapet end was loaded as designed. [Figure 25] FIG. 25 shows the results of a rear-side collision test when a load equivalent to the design load of the wall parapet end is applied. [Figure 26]FIG. 26 is a photograph showing the condition of the loading surface (front side) of the test specimen after loading equivalent to the design load on the cast-in-place wall parapet. [Figure 27] FIG. 27 shows the results of a frontal collision test when a load equivalent to the bearing capacity of the wall parapet end load is applied. [Figure 28] FIG. 28 shows the results of a rear-side collision test when a load equivalent to the bearing strength of the wall parapet end load is applied. [Figure 29] FIG. 29 is a photograph showing the condition of the loading surface side (front side) of the test specimen after loading equivalent to the bearing capacity of the cast-in-place wall parapet. [Figure 30] FIG. 30 is a photograph showing the condition of the opposite side (back side) of the specimen after loading equivalent to the bearing capacity of the cast-in-place wall parapet. [Figure 31] Figure 31 is a crack diagram showing cracks on a specimen after loading equivalent to the strength of a cast-in-place wall parapet. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, one embodiment of the fixing structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab according to the present invention will be described in detail with reference to the drawings.

[0030] [Anchoring structure between non-ferrous reinforcement bars of cast-in-place wall parapets and deck slabs] An anchorage structure 1 for connecting non-steel reinforcement bars of a cast-in-place wall parapet to a deck slab (hereinafter simply referred to as anchorage structure 1) according to an embodiment of the present invention will be described with reference to Figures 1 to 6. Figure 1 is a vertical cross-sectional view showing the configuration of the central part of the anchorage structure 1 according to an embodiment of the present invention.

[0031] As shown in Figure 1, the anchoring structure 1 between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab according to this embodiment was developed as a cast-in-place specification for a non-steel wall parapet for an MeL Slab (registered trademark), which uses short-fiber reinforced concrete containing non-ferrous organic short fibers in the aforementioned CFCC Slab (registered trademark), in which carbon fiber composite cables (CFCC) are arranged in two directions, perpendicular to the bridge axis and in the bridge axis direction, eliminating the need for reinforcement bars other than the carbon fiber composite cables. Of course, the deck to which the anchoring structure between the non-steel reinforcement bars of a cast-in-place wall parapet and the deck slab of this invention is applied is not limited to an MeL Slab (registered trademark), and can be applied to various decks.

[0032] When used as an anchoring structure for non-ferrous reinforcement, non-ferrous materials can ensure uniaxial performance by evenly distributing stress when subjected to tension. However, when bending, stress is concentrated at the bent section, leading to fracture at the bent section at a lower load than the guaranteed load. For example, the PC Engineering Society defines this as (0.05r / φ+0.3) × 0.8Pu. Therefore, taking into account the strength reduction at the bent section, calculations were made to ensure that the reduced tensile strength satisfied the yield strength of the rebar. The rebar equivalent to the nominal diameter of D13 rebar required in conventional structural design was set to φ13 RC carbon fiber rebar, while the rebar equivalent to the nominal diameter of D16 rebar required in structural design was set to φ16 (φ15.9). In other words, the non-ferrous reinforcing bar, carbon fiber rebar for RC, must be equal to or larger than the nominal diameter of the required rebar.

[0033] Additionally, the Japan Society of Civil Engineers states that if the inner bending radius of the reinforcement is less than 10 times the diameter of the reinforcement, it is necessary to bend it and then straighten it out to at least 10 times the diameter of the reinforcement. Therefore, in Anchorage Structure 1, the inner bending radius of the reinforcement is set to at least 2.5 times the inner bending radius of the reinforcing bar of the RC wall parapet (inner bending radius R = 13 mm x 2.5 = 32.5 mm), and the anchorage length is set to at least 12φ (= 12 x 13 = 156 mm). Another calculation method is to match the rigidity (elastic modulus x cross-sectional area) of the reinforcing material, but the above approach was adopted. There are no specific upper limits for the inner bending radius or anchorage length of the reinforcement, just like with regular rebar.

[0034] The carbon fiber reinforcement for RC used as the reinforcement for the anchorage structure 1 according to this embodiment is a reinforcement for RC in which the outer periphery of each strand of a seven-strand carbon fiber composite cable made of a composite of resin and resin fiber is covered with PET fiber to give it an uneven shape in order to improve adhesion to concrete, as shown in Fig. 2. Fig. 2 is a photograph showing the uneven shape of the carbon fiber reinforcement for RC.

[0035] Although we will not go into details here, this uneven carbon fiber reinforcement for RC complies with the "Guidelines for Reinforcement Bar Anchorages and Joints [2020 Edition] Japan Society of Civil Engineers," and has been compared in anchorage performance with J-shaped and L-shaped hooks of general reinforcing bars of each nominal diameter made of SD345, and confirmed to be at the same level as or better than general reinforcing bars.

[0036] As shown in Figure 1, the anchorage structure 1 is composed of a PC deck 2 made of MeL slab (registered trademark), and a wall parapet 3 formed by pouring cast-in-place concrete into the ground covering portion 2a of the PC deck 2.

[0037] In addition, the ground cover portion 2a, which is the joint between the PC deck slab 2 and the wall parapet 3, has steps 2b on the inside and outside of the concrete part of the PC deck slab 2, and these steps 2b function as concrete shear keys (concrete keys) at the joint between the PC deck slab 2 and the wall parapet 3.

[0038] (PC floor slab) As mentioned above, the PC deck slab 2 is a so-called MeL slab (registered trademark) made of non-ferrous material without using steel bars as reinforcement, and is equipped with a 15.2 mm diameter carbon fiber composite cable C1 arranged perpendicular to the bridge axis and a 19.3 mm diameter carbon fiber composite cable C2 arranged in the bridge axis direction.

[0039] The concrete mix for PC deck 2 is the same as that of the specimen described later, as shown in Table 2. The basic mix is ​​a water-binder ratio of 37%, a slump of 12cm, an air content of 4.5%, and a design strength of 60N / mm 2 This is a short fiber reinforced concrete containing 0.5 vol.% of non-ferrous short fibers such as polypropylene.

[0040] The PC deck 2 and the cast-in-place wall parapet 3 must then be joined on-site, but when conventionally casting wall parapets in-place, the reinforcement is typically extended to near the top of the wall parapet. However, to improve the transportation efficiency of the PC deck 2, the non-steel reinforcement that rises to the ground cover reinforcement is in the form of a loop joint, as described below. This is because using loop joints for the non-steel reinforcement minimizes stock in the precast factory. Furthermore, because carbon fiber reinforcement for RC is a material that cannot bend back, using loop reinforcement makes it less likely to break and more resistant to deformation that occurs during transportation and erection.

[0041] In addition, the ground covering reinforcement ML-3, which is made of RC carbon fiber reinforcement and is arranged in the ground covering portion 2a, will be described later together with the reinforcement of the wall parapet 3.

[0042] (Wall railing) Wall Parapet 3 is a cast-in-place wall parapet in which RC carbon fiber reinforcement bars are arranged as non-ferrous reinforcement and cast-in-place concrete with the same mix as the test specimen described below, as shown in Table 1. The concrete mix for Wall Parapet 3 has a basic mix of 60% water-binder ratio, 12.0cm slump, 4.5% air content, and a design strength of 30N / mm 2 , set actual strength 40N / mm 2 Furthermore, since the wall balustrade 3 is cast in place, a high-early-strength cement is used as the base material to impart early strength, and since it is necessary to impart spalling prevention performance, fiber-reinforced concrete with 0.4 vol% of short organic fibers such as polypropylene is used. Of course, the type of cement is not limited to high-early-strength cement, and general Portland cement can also be used.

[0043] Additionally, the non-steel reinforcement bars (reinforcements) made of carbon fiber reinforcement bars for RC in the anchorage structure 1, including the wall parapet 3, are made up of a combination of several types of reinforcement bars with different reinforcing bar arrangement shapes. There are three types of non-steel reinforcement bars in the parapet section, two types in the joint section, and one type in the ground cover section. However, this does not include the straight-shaped parapet straight reinforcement bars WL5 and deck straight reinforcement bars ML-4 that are arranged inside these reinforcement bars along the bridge axis (see Figure 1).

[0044] Specifically, as shown in Figure 1, the wall railing 3, which corresponds to the railing portion of the anchorage structure 1, is equipped with upper reinforcement WL3-U made of inverted U-shaped carbon fiber reinforcement for RC that corresponds to the outer shape of the cross-sectional shape of the wall railing 3, lower reinforcement WL3-L made of U-shaped carbon fiber reinforcement for RC that corresponds to the outer shape of the cross-sectional shape of the wall railing 3, and cross-sectional diagonal reinforcement WL4 that has a diagonal reinforcement portion on the cross section in the direction extending the second loop reinforcement ML-2 described below.

[0045] Figure 3 shows the individual non-steel reinforcement bars arranged in the balustrade portion (wall balustrade 3) of the anchorage structure 1. (a) shows upper reinforcement WL3-U, (b) shows lower reinforcement WL3-L, and (c) shows cross-sectional diagonal reinforcement WL4. As shown in Figure 3(a), upper reinforcement WL3-U is made of carbon fiber reinforcement for reinforced concrete (CFRC) with a diameter of 13 mm and a total length of 1085 mm, arranged at a predetermined pitch. Similarly, as shown in Figure 3(b), lower reinforcement WL3-L is made of carbon fiber reinforcement for reinforced concrete with a diameter of 13 mm and a total length of 1494 mm, arranged at a predetermined pitch. And, as shown in Figure 3(c), cross-sectional diagonal reinforcement WL4 is made of carbon fiber reinforcement for reinforced concrete with a diameter of 13 mm and a total length of 754 mm, arranged at a predetermined pitch. As mentioned above, the dimensions shown in Figure 3 are core-to-core lengths, and as mentioned above, the structure is bent with an inner bending radius R of 32.5 mm.

[0046] As shown in Figure 1, the straight-line railing straight reinforcement WL5, which is placed inside the upper reinforcement WL3-U and lower reinforcement WL3-L of the wall railing 3, is made of RC carbon fiber reinforcement with a diameter of 13 mm and a total length of 3,880 mm, corresponding to the total length of the wall railing 3.

[0047] Next, we will explain the non-steel reinforcement arranged in the joints and the ground cover of the anchorage structure 1 using Figure 4. Figure 4 is a diagram showing the non-steel reinforcement arranged in the joints and the ground cover of the anchorage structure 1, where (a) shows the first loop reinforcement ML-1 at the joint, (b) shows the second loop reinforcement ML-2 at the joint, and (c) shows the ground cover reinforcement ML-3. As shown in Figure 4(a), the first loop reinforcement ML-1 is made of carbon fiber reinforcement for RC, measuring 13 mm in diameter and 914 mm in total length, arranged at a predetermined pitch. Similarly, as shown in Figure 4(b), the second loop reinforcement ML-2 is made of carbon fiber reinforcement for RC, measuring 13 mm in diameter and 1283 mm in total length, arranged at a predetermined pitch.

[0048] Furthermore, these first loop reinforcement ML-1 and second loop reinforcement ML-2 are pre-arranged in the PC deck 2, which is a precast deck, and the reinforcement bars protruding from the ground covering portion 2a of the PC deck 2 become loop reinforcement. In this way, by making the reinforcement bars protruding from the top surface of the PC deck 2, which is a precast deck, into a loop joint shape, it is possible to minimize the stock space within the precast factory. Furthermore, because carbon fiber reinforcement bars for RC are a material that cannot bend back, by making them into loop reinforcement they can be made less likely to break and more resistant to deformation caused by the effects that occur during transportation and erection.

[0049] As shown in Figure 4(c), the reinforcement bars ML-3 that reinforce the reinforcement bar 2a are made of carbon fiber reinforcement bars for RC with a diameter of 13 mm and a total length of 976 mm, arranged at a predetermined pitch. As mentioned above, the dimensions shown in Figure 3 are the core-to-core length, and as mentioned above, they are bent with an inner bending radius R of 32.5 mm.

[0050] In addition, the straight deck slab straight reinforcement ML-4, which is arranged inside the first loop reinforcement ML-1, second loop reinforcement ML-2, and ground cover reinforcement ML-3 of the PC deck slab 2, is made of RC carbon fiber reinforcement with a diameter of 13 mm and a total length of 3,880 mm, corresponding to the total length of the ground cover section 2a (see Figure 1).

[0051] The non-steel reinforcement bars made of carbon fiber reinforcement bars for RC in the anchorage structure 1 described above were structurally designed based on a design concept in which, when a collision force 10 times the design impact force is applied to the wall parapet without reinforcement bars in the ground cover, the shear strength is considered to be the resistance width to resist shear action, based on the distance in the bridge axis direction at which diagonal cracks form behind the ground cover.

[0052] In addition, for anchorage structure 1, the shear load acting on the wall parapet was set based on the applied load obtained by applying an impact strength 10 times the design load to the RC wall parapet reinforced with steel bars, and concrete shear keys and reinforcement materials were placed to resist this.

[0053] In addition, as shown in Figure 1, at the end of the wall parapet 3 of the anchorage structure 1, a 350mm x 250mm square 6-cell CFRP grid 4 made of carbon fiber reinforced polymer (CFRP) was placed as shear reinforcement to provide shear resistance. Here, the end refers to a position 170mm axially from the end of the wall parapet 3 and 300mm from the top of the wall parapet 3, where a collision force 10 times the design impact force was applied to the wall parapet without reinforcement in the ground guard, and a distance of 700mm in the axial direction of the bridge from the end face of the wall parapet 3 where a diagonal crack occurred behind the ground guard.

[0054] As mentioned above, the anchorage structure 1 uses a PC deck 2, which is a CFCC slab (registered trademark) that has been pre-stressed in two directions, and therefore it is expected that the shear strength will be improved by the prestress introduced into the ground cover section 2a by the carbon fiber composite cable (CFCC) C2 arranged in the bridge axis direction of the PC deck 2.

[0055] As mentioned above, in order to ensure the strength of the cast-in-place wall parapet 3 of the anchorage structure 1, carbon fiber reinforcement for RC was used as non-ferrous reinforcement, and organic short fibers (volume ratio 0.4% for the parapet, 0.5% for the deck) were mixed into the concrete.

[0056] As described above, in the anchorage structure 1, the shear strength of the joint between the PC deck slab 2 and the cast-in-place wall parapet 3 is ensured by the shear strength of the carbon fiber reinforcement bars for RC, which was experimentally verified, in addition to the concrete shear key. Furthermore, for the end specifications where the resistance width is narrow, shear strength is ensured by placing a lattice-shaped CFRP grid 4 made of carbon fiber reinforced plastic (CFRP) at the point where it bridges the diagonal shear cracks from the concrete key.

[0057] In addition, in Anchorage Structure 1, the bending strength of the joint (anchorage section) between the MeL Slab (registered trademark) and the cast-in-place wall parapet was ensured by using RC carbon fiber reinforcement, which had experimentally verified anchorage strength. In particular, prior studies of precast non-steel wall parapets showed that without reinforcement in the base guard section 2a, diagonal cracks would develop behind the base guard section, causing the wall parapet to collapse and fail, as shown in Figures 5 and 6. The diagonal cracks measured were 1400 mm. However, since the Standard Specifications and Commentary for Vehicle Guard Fences stipulate that the effective width is designed to be twice the height from the point of impact load application to the cross-sectional inspection point, the design value was larger than the actual resistance width, resulting in a risky assessment. Figure 5 is a photograph showing diagonal cracks without reinforcement in the 800 mm base guard section, and Figure 6 is a photograph showing diagonal cracks without reinforcement in the 600 mm base guard section.

[0058] According to the anchoring structure 1 of this embodiment described above, the durability of the entire structure can be significantly improved without the risk of rusting, and the non-steel reinforcing bars have shear resistance and do not concentrate stress at the bending processed parts, resulting in a mechanically efficient reinforcement arrangement.

[0059] Furthermore, according to the anchoring structure 1, the carbon fiber reinforcement bars for RC of the cast-in-place wall parapet 3 that are fixed to the PC deck 2 and protrude upward from the ground covering portion 2a of the PC deck 2 are loop reinforcement bars, so that the storage space required for the PC deck 2 within the precast factory can be minimized and the protruding carbon fiber reinforcement bars for RC are less likely to break and can resist deformation when subjected to the effects that occur during transportation and erection.

[0060] Furthermore, according to the anchorage structure 1, prestress is applied to the PC deck 2 in two directions in advance, so it is expected that the shear strength will be improved by the prestress introduced into the ground cover part 2a by the RC carbon fiber reinforcement bars arranged in the bridge axis direction of the PC deck 2.

[0061] Furthermore, according to the anchorage structure 1, since the PC deck slab 2 is made of fiber-reinforced concrete, it is possible to eliminate the need for reinforcing bars other than the non-ferrous cables of the tendons that introduce prestress.

[0062] Furthermore, according to the anchorage structure 1, a concrete shear key is provided at the step 2b in the ground cover portion 2a, so that the shear load acting on the wall balustrade can be set and satisfied based on the applied load obtained by applying an impact strength 10 times the design load to an RC wall balustrade reinforced with steel bars.

[0063] In addition, according to the anchorage structure 1, a CFRP grid 4 is arranged, so that the CFRP grid 4 can resist the shear force acting at the joint between the cast-in-place wall parapet and the precast deck slab, thereby improving the shear resistance.

[0064] The fixing structure 1 according to the embodiment of the present invention has been described in detail above. However, the above-described and illustrated embodiments are merely specific embodiments for carrying out the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these embodiments.

[0065] In particular, carbon fiber reinforcement bars for RC and carbon fiber composite cables (CFCC) have been used as examples of non-ferrous reinforcement bars, but the present invention is not limited to reinforcement materials made of carbon fiber, and any continuous fiber reinforcement material, which is a composite material combining aramid fiber, glass fiber with epoxy resin, vinyl ester resin, etc., which does not rust, may be used.

[0066] [Experiment for estimating concrete strength] Next, we will explain the collision tests of non-ferrous wall balustrades that were conducted to confirm the deformation characteristics and stress state as the collision resistance performance of cast-in-place wall balustrades made of non-ferrous materials.

[0067] <Specimen> First, we will explain the outline of the non-steel wall balustrade used as the specimen for the collision test. The specimen used in the collision test is a specimen with the same configuration as the aforementioned anchorage structure 1, consisting of a wall balustrade and a simulated deck section. The wall balustrade uses carbon fiber reinforcement for RC (CFCC for RC) with a diameter of φ13 or φ15.9 as reinforcement and is made of fiber-reinforced concrete with 0.4% volumetric polypropylene short fiber, as specified for spalling prevention. The simulated deck simulates the aforementioned MeL Slab (registered trademark), a non-steel deck, and uses carbon fiber composite cables as tension members in the bridge axis direction and perpendicular to the bridge axis, and fiber-reinforced concrete with 0.5% volumetric polypropylene short fiber. The test levels were (1) center loading and (2) edge loading.

[0068] (Concrete mix for wall parapets) The concrete mix for the wall parapet is shown in Table 1. The concrete is assumed to be a general mix, with a water-to-binder ratio of 60%, a slump of 12.0 cm, an air content of 4.5%, and a design strength of 30 N / mm 2 , set actual strength 40N / mm 2 A feature of this mix is ​​that it uses early-strength cement as the base material to impart early strength. Also, due to the conditions of the site application, it is necessary to impart spalling prevention performance to the wall parapet, so it is a fiber-reinforced concrete that mixes in 0.4 vol.% short polypropylene fibers.

[0069] [Table 1]

[0070] (Concrete mix for mock deck) The concrete mix for the simulated non-ferrous deck is shown in Table 2. The basic mix is ​​a water-binder ratio of 37%, a slump of 12cm, an air content of 4.5%, and a design strength of 60N / mm. 2 This is a fiber-reinforced concrete containing 0.5 vol.% short polypropylene fibers.

[0071] [Table 2]

[0072] The physical properties of the carbon fiber composite cable (CFCC) and carbon fiber reinforcement for RC (CFCC for RC) are shown in Table 3. The physical properties of the carbon fiber grid placed on the end specimen are shown in Table 4.

[0073] [Table 3]

[0074] [Table 4]

[0075] (Specimen overview) As an outline of the wall parapet part that was the test specimen, the standard part is shown in Figure 7 and the end part in Figure 8. Figure 7 shows the standard part of the test specimen, with (a) being a vertical cross section, (b) being a side view seen from the opposite side of the collision surface, and (c) being a side view seen from the collision surface. Figure 8 also shows the end part of the test specimen, with (a) being a vertical cross section, (b) being a side view seen from the opposite side of the collision surface, and (c) being a side view seen from the collision surface. The test specimen was 4m long.

[0076] The wall parapets were reinforced with φ13 and φ15.9 carbon fiber reinforcement bars for RC (CFCC for RC), and the end-loaded basal section was reinforced with carbon fiber grids. The simulated deck was a non-steel deck, modeled after the MeL Slab (registered trademark). To simulate the prestress stress of the actual deck in the bridge axis direction, CFCC φ19.3 was used as the tendon, adjusting the height and tension. CFCC φ15.2 was placed perpendicularly, but prestressing was not implemented due to the constraints of the specimen dimensions. The deck thickness was set at 400 mm due to the limitations of the test equipment, and D19 rebar was placed under the deck as safety rebar. The reinforcement arrangement of the specimens is shown in Figure 9 for the standard deck section, Figure 10 for the standard wall parapet section, Figure 11 for the end deck section, and Figure 12 for the end wall parapet section. The standard part of the completed test specimen is shown in Figure 13, and the end part is shown in Figure 14.

[0077] Fig. 9 is a photograph showing the reinforcement of the specimen in the standard section deck slab, and Fig. 10 is a photograph showing the reinforcement of the specimen in the standard section wall balustrade. Fig. 11 is a photograph showing the reinforcement of the specimen in the end section deck slab, and Fig. 12 is a photograph showing the reinforcement of the specimen in the end section wall balustrade. Fig. 13 is a photograph showing the completed standard section specimen, and Fig. 14 is a photograph showing the completed end section specimen.

[0078] (Test Overview) The collision test was conducted in accordance with the NEXCO test method "Performance test method for precast wall parapet joint structure, Test Method 441." The outline of the collision test is as follows:

[0079] Test method: A weight (70 kN) was collided with the wall parapet (see Figure 15). Figure 15 shows the collision test equipment, with (a) being a side view, (b) being a plan view, and (c) being a front view seen from the direction of impact of the weight.

[0080] Collision location: Center of wall parapet, end of wall parapet Loading method: The impact energy was changed by adjusting the lifting distance of the weight, and a load equivalent to the design load based on the cast-in-place wall parapet of the bridge and the strength of the cast-in-place wall parapet was applied. In addition, a buffer material (made of acrylonitrile butadiene rubber, hardness 30, thickness 215 mm) was installed at the loading position 300 mm from the top of the wall parapet.

[0081] Test level (1) Wall parapet center loading: Type SB, impact angle 90° (2) Wall parapet end loading: Type SB, impact angle 90° Loading step There are two loading steps: (1) Design crash load equivalent: Class SB x 1, crash intensity 2.8kJ (2) Equivalent strength of cast-in-place wall parapet: Class SB x 10, impact strength 28kJ

[0082] This crash test device allows you to freely set the impact energy by changing the height at which the weight is dropped via the rail. The impact strength is Is=(1 / 2)·W / g·v 2 sin 2 θ, where Is is the impact intensity (kJ), w is the total vehicle mass (kN), and g is the gravitational acceleration (m / s 2 ), v: impact speed (m / s), θ: impact angle (90deg). During the test, a displacement meter was used to measure the horizontal displacement of the weight for a total of 3 seconds at 0.0005 second intervals (2kHz). The point at which the weight came into contact with the rubber cushion was determined from the horizontal displacement and the load measured by the load cell attached to the tip of the weight, and the speed was calculated to determine the impact degree in the section 0.05 seconds prior to this point. After the test, observations were made for cracks.

[0083] (Evaluation and Judgment) Evaluation criteria were determined according to each load. The criteria are as follows: (1) When loaded with design load equivalent There should be no harmful cracks (crack width of 0.2 mm as a guideline) or scattering of component parts. No residual strain occurs in the wall parapets and joints (within the elastic range and below the yield strain). (2) When loading equivalent to the strength of cast-in-place wall parapets There is no peeling of the cover concrete at the rear joint of the wall balustrade base, and there is no breakage or loss of the tension members at the joint.

[0084] (Test results) (1-1) Loading the central part of the wall parapet Two types of central loading were carried out: (1) loading equivalent to the design load and (2) loading equivalent to the strength of the cast-in-place wall parapet. The hardened physical properties of the specimens on the day of the test are shown in Table 5 below.

[0085] [Table 5]

[0086] Figures 16 and 17 show the test results (1) when the design load was applied. Figure 20 shows the condition of the test specimen after the test. Figure 16 shows the results of a frontal collision test when the center of the wall parapet was loaded with the design load, and Figure 17 shows the results of a rearward collision test when the center of the wall parapet was loaded with the design load. Figure 18 is a photograph of the test specimen after the design load was applied. As a result, it was confirmed that the impact strength was 3.1 kJ, which was satisfactory compared to the target value of 2.8 kJ. Observation of the test specimen showed no cracks, no scattered components, and no residual strain in the RC carbon fiber reinforcement in the wall parapet and joints, so the results were deemed to be acceptable.

[0087] Next, (2) Figures 19 and 20 show a list of the results of loads equivalent to the strength of cast-in-place wall parapets. Also, Figures 21 and 22 show photographs of the specimens after the tests, and Figure 23 shows a crack diagram. Figure 19 shows the results of a front-side collision test when the center of the wall parapet is loaded and a load equivalent to the strength is applied, and Figure 20 shows the results of a rear-side collision test when the center of the wall parapet is loaded and a load equivalent to the strength is applied. Also, Figure 21 is a photograph showing the condition of the loaded side (front side) of the specimen after the load equivalent to the strength of the cast-in-place wall parapet, and Figure 22 is a photograph showing the condition of the opposite side (rear side) of the specimen after the load equivalent to the strength of the cast-in-place wall parapet. Finally, Figure 23 is a crack diagram showing the cracks in the specimen after the load equivalent to the strength of the cast-in-place wall parapet.

[0088] As a result, the impact strength was confirmed to be 31.4kJ, satisfying the target value of 28kJ. Observation of the specimen revealed cracks along the bridge axis at the base of the balustrade on the loading side, fan-shaped cracks centered around the loading point, and vertical cracks at the rear side at the loading point. However, there was no spalling in the cover concrete at the rear-side joint of the wall balustrade base, and no fractures or breaks were observed in the tensile members at the joint. Strain values ​​were all lower than the fracture strain of 11,829μ for carbon fiber reinforcement for reinforced concrete (CFCC for reinforced concrete), confirming soundness. The wall members had the greatest strain at the rear of the loading point, reaching 1,588μ at the time of impact, but the residual strain was 431μ, significantly smaller than the fracture strain. Furthermore, strain at the front of the pier guard was confirmed to be at most 180μ, confirming sufficient soundness. Based on these findings, the results were deemed acceptable.

[0089] In summary, the performance evaluation results for central loading are as shown in Table 6. The results are judged to be acceptable.

[0090] [Table 6]

[0091] (1-2) Loading at the end of the wall railing Two types of edge loading were carried out: (1) loading equivalent to the design load and (2) loading equivalent to the strength of the cast-in-place wall parapet. The hardened physical properties of the specimens on the day of the test are shown in Table 7 below.

[0092] [Table 7]

[0093] Figures 24 and 25 show the test results (1) when the design load was applied. Figure 26 shows photographs of the specimen after the test. Figure 24 shows the results of a frontal impact test when the design load was applied to the end of the wall balustrade, and Figure 25 shows the results of a rearward impact test when the design load was applied to the end of the wall balustrade. Figure 26 is a photograph showing the condition of the loaded side (front side) of the specimen after the design load was applied to the cast-in-place wall balustrade. The impact strength was confirmed to be 3.6 kJ, which was satisfactory compared to the target value of 2.8 kJ. Observation of the specimen revealed no cracks, no scattering of structural components, and no residual strain in the carbon fiber reinforcement for reinforced concrete (CFCC for RC) in the balustrades and joints. Therefore, the results were deemed acceptable.

[0094] Next, Figures 27 and 28 show a list of measurement results for (2) cast-in-place wall parapets when subjected to loads equivalent to their strength. Photographs of the specimen after the test are shown in Figures 29 and 30, and a crack diagram is shown in Figure 31. Figure 27 shows the results of a front-side collision test when subjected to loads equivalent to their strength with the wall parapet end loaded. Figure 28 shows the results of a rear-side collision test when subjected to loads equivalent to their strength with the wall parapet end loaded. Figure 29 is a photograph showing the condition of the loaded side (front side) of the specimen after the load equivalent to their strength with the cast-in-place wall parapet. Figure 30 is a photograph showing the condition of the opposite side (rear side) of the specimen after the load equivalent to their strength with the cast-in-place wall parapet. Finally, Figure 31 is a crack diagram showing the cracks in the specimen after the load equivalent to their strength with the cast-in-place wall parapet.

[0095] As a result, the impact strength was confirmed to be 33.4kJ, satisfying the target value of 28kJ. Observation of the test specimens revealed that fan-shaped cracks had appeared on the loading surface, centered around the loading point, affecting the base of the pier guardrail. Cracks had appeared on the rear surface, but the number was smaller than on the loading surface. Shear cracks had also appeared in the concrete behind the pier guardrail, confirming the effective contribution of the concrete shear keys and reinforcement. Furthermore, there was no spalling in the cover concrete at any point, including the rear joint at the base of the wall parapet, and no fractures or breaks were observed in the tensile members at the joints. The strain values ​​were all smaller than the fracture strain of 11,829μ for carbon fiber reinforcement for reinforced concrete (CFCC for reinforced concrete), confirming that no fractures had occurred. The wall member had the largest strain at the front of the loading point, measuring 4,844 μm at the time of impact, but the residual strain was 1,346 μm, considerably smaller than the fracture strain at both impact and residual strain. Furthermore, when the strain at the front of the ground shield was checked, it was found to be at most 1,971 μm, confirming that the structure was in good condition. Strain No. 4 at the front of the ground shield could not be measured due to a strain gauge breaking during manufacturing. Furthermore, strain No. 3 at the front of the ground shield, based on the results of the time-dependent strain analysis shown below, reached a strain value of 4,245 μm well before the impact load reached its maximum relative to the surrounding strain, and then became unmeasurable. This is believed to be due to lead wire breakage caused by displacement. Based on the above, it was determined that although cracks had occurred, the reinforcement material had not fractured, and the results were deemed acceptable. [Explanation of symbols]

[0096] 1: Fixed structure 2: PC deck (precast deck) 2a: Ground covering part 2b: Step (shear key) C1, C2: Carbon fiber composite cable S1, S2: Caution steel bars ML-1: 1st loop muscle (loop muscle) ML-2: Second loop muscle (loop muscle) ML-3: Earth-covering muscle ML-4: Floor slab straight line 3: Cast-in-place wall parapet 4: CFRP grid WL3-U: Upper muscles WL3-L: Lower muscles WL4: Diagonal cross section WL5: Straight railing

Claims

1. A fixing structure between the non-steel reinforcement of the cast-in-place wall parapet and the deck slab, The non-steel reinforcement bar must have a diameter equal to or greater than the nominal diameter of the reinforcing bar required in the structural design, the inner bending radius of the non-steel reinforcement bar must be 2.5 times or more the inner bending radius of the reinforcing bar, and the anchorage length of the non-steel reinforcement bar must be 12 times or more the diameter. This is a fixing structure between the non-ferrous reinforcement bars of the cast-in-place wall parapet and the deck slab.

2. The non-ferrous reinforcement is a carbon fiber reinforcement material with a stranded wire structure, which is made of a composite of resin and resin fiber and has irregularities formed on each outer wire.

2. The anchoring structure for the non-steel reinforcement of the cast-in-place wall parapet and the deck slab according to claim 1.

3. The deck is a precast deck reinforced with non-ferrous reinforcement, and the non-ferrous reinforcement provided at the joint between the precast deck and the wall parapet protruding from the ground covering portion is a loop reinforcement.

2. The anchoring structure for the non-steel reinforcement of the cast-in-place wall parapet and the deck slab according to claim 1.

4. The precast deck is a PC deck to which prestress has been applied in two directions by carbon fiber composite cables.

4. The anchoring structure for the non-steel reinforcement of the cast-in-place wall parapet and the deck slab according to claim 3.

5. The PC deck is made of short fiber reinforced concrete mixed with organic short fibers.

5. The anchoring structure for the non-steel reinforcement of the cast-in-place wall parapet and the deck slab according to claim 4.

6. The ground cover part of the precast deck is provided with a step as a shear key.

4. The anchoring structure for the non-steel reinforcement of the cast-in-place wall parapet and the deck slab according to claim 3.

7. The non-steel reinforcement bars are arranged with the shear load acting on the wall parapet set based on the applied load obtained by applying an impact strength 10 times the design load to an RC wall parapet reinforced with steel bars.

7. The anchoring structure for the non-steel reinforcement of the cast-in-place wall parapet and the deck slab according to claim 6.

8. A grid-shaped CFRP grid is placed on the ground cover of the precast deck as shear reinforcement.

8. The anchoring structure for the non-steel reinforcement of the cast-in-place wall parapet and the deck slab according to claim 7.

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