Bridge pier structure

Abstract

To provide a bridge pier structure that can be constructed safely and efficiently alternative to traditional reinforced concrete piers.SOLUTION: A bridge pier structure 1 includes multiple vertically-oriented reinforced core materials 13, 13..., which are buried across a top slab 11 and a bridge pier body 12, the reinforced core material 13 includes an elongated flat web part, a flange part extending from both sides of the web part in a direction intersecting the front and / or back surface of the web part, and adhesion strengthening means for adhering the web part to concrete that constitutes the top slab 11 and the bridge pier body 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention mainly relates to a pier structure in which a pier body is erected on a top plate supported by a foundation such as a steel pipe sheet pile caisson foundation.

Background Art

[0002] As piers for supporting bridges and elevated roads, those of the "steel pipe sheet pile caisson foundation" type are widely used because they have a large supporting force and the overall planar dimensions of the pier can be reduced due to the caisson rigidity.

[0003] As shown in FIGS. 10 to 12, a pier 20 of the "steel pipe sheet pile caisson foundation" type forms a closed caisson 23 by a plurality of steel pipe sheet piles 22, 22 driven into the ground 21, connects the head of this caisson 23 by a top plate 24 made of reinforced concrete, and erects a pier body 25 made of reinforced concrete on the top plate 24.

[0004] Such a pier 20, as shown in FIGS. 10 and 12, includes a concrete top plate 24 in which a main reinforcement group 27 formed by arranging a plurality of tension reinforcement members 26, 26 made of bar-shaped reinforcing bars in a lattice pattern in the horizontal direction is embedded in a plurality of upper and lower stages, and a concrete pier body 25 erected on the top plate 24, and has a structure in which a plurality of reinforcing core materials 28, 28... made of bar-shaped reinforcing bars arranged vertically across the top plate 24 and the pier body 25 are embedded.

[0005] As shown in FIGS. 10 to 12, the reinforcing core materials 28, 28... are arranged at intervals in the circumferential direction so as to be cylindrical in plan view, and a core material group 29 composed of the plurality of reinforcing core materials 28, 28... is constrained by a plurality of hoop bars or intermediate hoop bars 30, 30... arranged at intervals in the axial direction of the reinforcing bars on the outside.

[0006] On the other hand, since the top slab 24 has a predetermined thickness, generally about 5m to 10m, as shown in Figures 10 and 12, the main reinforcement groups 27, 27, which consist of multiple tensile reinforcement members arranged in a grid pattern at intervals within the concrete, are arranged in multiple layers vertically or horizontally at intervals in the cross section perpendicular to the reinforcement axis of the structure. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2016-204861 [Overview of the project] [Problems that the invention aims to solve]

[0008] In recent years, standards for seismic design have been revised to cope with increasingly massive earthquakes, and high bending and shear strength are often required. As a result, reinforcing bars are densely packed, raising concerns about reduced constructability.

[0009] Such dense reinforcement arrangements, where a large number of large-diameter reinforcing bars are placed at small intervals (for example, 100-150 mm), can lead to decreased work efficiency due to the complexity of reinforcing bar assembly and inspection, and may also compromise worker safety due to limited workspace.

[0010] Furthermore, with overly dense reinforcement, there were concerns about the concrete's ability to fill during placement, which could lead to a decrease in the protective performance of the main steel material, potentially resulting in a decline in the quality of the reinforced concrete structure.

[0011] When reinforcing core materials are subjected to repeated loads on the bridge pier due to earthquakes or other events, they can plastically deform beyond their yield strength. This causes the largest moment to act at the plastic hinge section, which is the connection point with the top slab in the bridge pier body, where the rotational rigidity has been lost like a hinge. At this point, the reinforcing core material on the compression side may buckle and bulge, potentially causing the concrete cover to spall. Therefore, it is necessary to shorten the vertical pitch of the stirrups and intermediate stirrups that restrain the core material groups, which is a cause of overcrowded reinforcement.

[0012] On the other hand, since the top slab generally has a thickness of about 5m to 10m, it is common for the main reinforcement group, consisting of multiple reinforcing bars spaced apart within the concrete, to be arranged in multiple layers vertically or horizontally, also spaced apart within the structure.

[0013] Normally, reinforcing bars are tied together with binding wire. Therefore, pre-assembling the main reinforcing bar units in a factory and transporting them to the construction site for installation is difficult because the reinforcing bars themselves are prone to bending, and the binding wire alone does not provide sufficient strength, causing them to easily come apart.

[0014] Therefore, prefabrication of unitized reinforcing bars is difficult. For example, when arranging multiple layers of reinforcing bars, the lower layers are assembled at the construction site, and then a pre-fabricated steel frame (a so-called support frame) is installed. The upper layers of reinforcing bars are then assembled using this frame as support, which results in poor work efficiency.

[0015] Therefore, in view of these conventional problems, the present invention aims to provide a bridge pier structure that can be constructed safely and efficiently. [Means for solving the problem]

[0016] The invention described in claim 1, which solves the conventional problems described above, is a bridge pier structure comprising a concrete top plate in which horizontal tensile reinforcing members are embedded in multiple vertically arranged stages, a concrete bridge slab erected on the top plate, and a plurality of vertically oriented reinforcing core members embedded in the top plate and the bridge slab, wherein the reinforcing core member comprises an elongated flat web portion, flange portions extending from both sides of the web portion in a direction intersecting the surface and / or back surface of the web portion, and adhesion strengthening means for adhering the web portion to the concrete constituting the top plate and the bridge slab, The reinforcing core material is positioned in the bridge truss with its weak axis facing the direction in which the main bending moment assumed in the design of the bridge truss acts. It is the matter.

[0017] Claim 2 The features of the invention described are, Claim 1 In addition to the above configuration, the reinforcing core material is composed of two types of members: a core member for the plastic hinge portion applied to the plastic hinge portion of the bridge truss, and a thin-walled core member applied to the portion other than the plastic hinge portion, wherein the web portion and flange portion of the thin-walled core member are formed to be thinner than the web portion and flange portion of the core member for the plastic hinge portion.

[0018] Claim 3 The features of the invention described are, Claim 1 or 2 In addition to the above configuration, the adhesion-enhancing means includes a plurality of rod-shaped members protruding from the surface and / or back surface of the web portion. It is the matter.

[0019] Claim 4 The features of the invention described are, Claim 3 In addition to the above configuration, the flange portion is formed to a width that allows the compressive force generated by the Poisson effect of the web portion to act effectively, and the number of rod-shaped members is such that they can bear the shear force obtained by subtracting the burden due to the frictional force generated between the flange portion and the concrete due to the Poisson effect of the web portion from the axial yield tensile force of the reinforcing core material.

[0020] The features of the invention described in claim 5 are, Claims 1 to 4In addition to any one of the configurations, the tensile reinforcement member includes an elongated flat web portion, and flange portions that project from both side portions of the web portion in a direction intersecting the front and / or back surface of the web portion. The web portion and the concrete that constitutes the top plate It is provided with adhesion strengthening means for adhering the The web portion and the concrete that constitutes the top plate .

[0021] Claim 6 The feature of the invention described in Claim 6 is Claim 5 In addition to the configuration of Claim 5 , it is provided with a group of tensile reinforcement members in which a plurality of the tensile reinforcement members arranged at intervals in the horizontal direction are connected by a connecting member.

[0022] Claim 7 The feature of the invention described in Claim 7 is Claim 6 In addition to the configuration of Claim 6 , a plurality of the groups of tensile reinforcement members are arranged at intervals in the vertical direction, and the groups of reinforcement members are connected and unitized by a group connecting member.

[0023] Claim 8 The feature of the invention described in Claim 8 is Claims 5 to 7 In addition to any one of the configurations, the tensile reinforcement member is arranged with the weak axis side facing the direction in which the main bending moment assumed in the design of the top plate acts on the top plate.

[0024] Claim 9 The feature of the invention described in Claim 9 is Claim 8 In addition to the configuration of Claim 8 , the tensile reinforcement member is formed with through holes penetrating the web portion.

[0025] Claim 10 The feature of the invention described in Claim 10 is Claims 5 to 7 In addition to any one of the configurations, the tensile reinforcement member is arranged with the strong axis side facing the direction in which the main bending moment assumed in the design of the top plate acts on the top plate. <000011'">

Effect of the Invention

[0026] The bridge pier structure according to the present invention, by having the configuration of claim 1, can bear the tensile force that is borne by multiple reinforcing bars in a conventional reinforced concrete bridge pier, with a single reinforcing core material. This allows for a smaller number of reinforcing core materials compared to the number of reinforcing bars in a conventional reinforced concrete bridge pier, thus avoiding overcrowded reinforcement and enabling efficient construction. Furthermore, it is possible to ensure a sufficient effective height for the reinforcing core material relative to the concrete, and also to reduce the concrete cross-section to achieve a predetermined effective height.

[0027] Furthermore, in the present invention, Claim 2 By incorporating this configuration, it is possible to streamline the design while ensuring sufficient load-bearing capacity.

[0028] Furthermore, in the present invention, Claim 3 By incorporating this configuration, it is possible to ensure higher adhesion strength between the reinforcing core material and the concrete, and to disperse cracks that occur in the concrete.

[0029] Furthermore, in the present invention, Claim 4 By incorporating this configuration, when a tensile force acts on the reinforcing core material, the Poisson effect of the web portion reduces the distance between the opposing flange portions, thereby restraining the concrete with the flange portions. This increases the frictional force between the flange portions and the concrete, thereby reducing the load on the rod-shaped members and allowing for a reduction in the number of rod-shaped members.

[0030] Furthermore, in the present invention, Claim 5 By incorporating this configuration, the tensile force that would normally be borne by multiple reinforcing bars in the top slab of a conventional reinforced concrete structure can be borne by a single tensile reinforcing member. This allows for a smaller number of tensile reinforcing members compared to the number of reinforcing bars in the top slab of a conventional reinforced concrete structure, thus avoiding overcrowded reinforcement and enabling efficient construction.

[0031] Furthermore, in the present invention, Claims 6 to 7By incorporating this configuration, the structure can be prefabricated using tensile reinforcement members. The tensile reinforcement members can be pre-assembled at a factory, manufacturing yard, or on a barge on land, and then transported and installed as a single unit in their assembled state, thereby reducing labor at the construction site.

[0032] Furthermore, in the present invention, Claim 8 By incorporating this configuration, it is possible to ensure a sufficient effective height for the tensile reinforcement member relative to the concrete, and at the same time, reduce the concrete cross-section to achieve a predetermined effective height.

[0033] Furthermore, in the present invention, Claim 9 By incorporating this configuration, not only is air trapped during concrete placement prevented, but the structure, similar to a perforated steel plate dowel, increases adhesion to the surrounding concrete, ensuring proper concrete filling. Furthermore, a vibrator can be inserted through the through-holes to perform compaction.

[0034] Furthermore, in the present invention, Claim 10 By incorporating this configuration, the bending moment can be resisted even more effectively. [Brief explanation of the drawing]

[0035] [Figure 1] This is a cross-sectional view showing an example of a bridge pier structure according to the present invention. [Figure 2] This is a cross-sectional view taken along the line XX shown above. [Figure 3] This is a cross-sectional view taken along the YY line shown above. [Figure 4] This is a perspective view showing the assembled group of tensile reinforcement members as described above. [Figure 5] (a) is an enlarged cross-sectional view showing the reinforcing core material or tensile reinforcing member in Figure 1, (b) is a plan view thereof, (c) is a plan view showing another example thereof, and (d) is an enlarged cross-sectional view showing another example of the tensile reinforcing member thereof. [Figure 6](a) is a flowchart showing the design method for the rod-shaped member of the reinforcing core material or tensile reinforcing member mentioned above, and (b) is a flowchart showing the friction force calculation method in the same flowchart. [Figure 7] This is a front view showing an embodiment of an alternating load experiment to confirm the effects of the present invention. [Figure 8] This graph shows the results of the alternating load experiment described above. [Figure 9] This is a photograph showing the damage condition of the test specimens during the alternating load experiment described above. [Figure 10] This is a cross-sectional view showing an example of a conventional bridge pier structure. [Figure 11] This is a cross-sectional view taken along the line XX shown above. [Figure 12] This is a cross-sectional view taken along the YY line shown above. [Modes for carrying out the invention]

[0036] Next, embodiments of the bridge pier structure 1 according to the present invention will be described based on the examples shown in Figures 1 to 9. In the figures, reference numeral 1 denotes the bridge pier structure 1, and reference numeral 2 denotes the ground.

[0037] The pier structure 1 comprises a concrete top plate 11 with horizontally oriented tensile reinforcing members 3,3… embedded in multiple vertically arranged layers, a concrete bridge slab body 12 erected on the top plate 11, and multiple vertically oriented reinforcing core members 13,13… embedded across the top plate 11 and the bridge slab body 12, with the top plate 11 supported by a steel pipe sheet pile caisson foundation 14. In this embodiment, the case where the top plate 11 and the bridge slab body 12 are rectangular in plan view is described as an example, but the shape of the top plate 11 and the bridge slab body 12 is not limited to this, and for example, they may be circular or oval in plan view.

[0038] This bridge pier structure 1 reduces construction labor by using tensile reinforcement members 3,3… and reinforcing core members 13,13… made of steel materials such as H-beams and I-beams, instead of the multiple reinforcing bars used in typical reinforced concrete bridge piers.

[0039] The steel pipe sheet pile well foundation 14 is formed by a closed well casing created by multiple steel pipe sheet piles 15, 15… driven into the ground 2. A concrete top slab 11 is constructed inside the head of this well casing, and the steel pipe sheet piles 15, 15… are connected by the top slab 11.

[0040] As shown in Figures 1 and 3, the top slab 11 is equipped with one or more prefabricated tensile reinforcing member groups 9,9 arranged in one or more stages (two stages in this embodiment), each consisting of multiple tensile reinforcing members 3,3... arranged at horizontal intervals from one another. These tensile reinforcing member groups 9,9 are embedded in the concrete of the top slab 11, forming a reinforced concrete structure that replaces the conventional RC structure.

[0041] In this embodiment, considering efficiency during construction, the tensile reinforcement member groups 9,9 arranged in multiple vertical tiers (two tiers in this embodiment) are connected by group connecting members 10,10 to form a tensile reinforcement member group unit 16. However, the tensile reinforcement member groups 9,9 may also be used independently.

[0042] Here, the term "reinforced concrete structure" includes not only RC structures that use tensile reinforcing members 3,3… instead of general bar-shaped reinforcing bars, but also RC structures that use tensile reinforcing members 3,3… in combination with bar-shaped reinforcing bars. Furthermore, in this invention, bar-shaped reinforcing bars may be used in combination depending on the shape of the structure to be manufactured, construction conditions, etc.

[0043] As shown in Figure 4, the tensile reinforcement member group 9,9 consists of multiple tensile reinforcement members 3,3… arranged horizontally at intervals from each other, with the ends of the tensile reinforcement members 3,3… connected by connecting members 8,8 to form a prefabricated structure. Note that tensile reinforcement member 3 may also be used as a connecting member 8.

[0044] The two tensile reinforcement member groups 9, 9 are arranged in two tiers with vertical spacing between them, and the tensile reinforcement member groups 9, 9 are connected to each other by group connecting members 10, 10 made of H-shaped steel or channel steel, etc., forming a unit.

[0045] In the above embodiment, an example was described in which the tensile reinforcement member groups 9,9 were connected by group connecting members 10,10 to form a unit. However, each tensile reinforcement member group 9,9 may be used independently without being connected by group connecting members 10,10.

[0046] Furthermore, depending on the thickness of the top plate 11, the tensile reinforcement members 9 may be arranged in a single layer rather than in multiple layers.

[0047] Furthermore, each tensile reinforcing member 3, 3... may be arranged independently without being connected by the connecting member 8.

[0048] Furthermore, the lower parts of reinforcing core materials 13, 13… are embedded in the top plate 11, arranged in a rectangular cylindrical shape with spacing in the circumferential direction, and each reinforcing core material 13, 13… protrudes upward from the upper surface of the top plate 11.

[0049] As shown in Figures 1 and 2, the bridge truss body 12 is equipped with a group of reinforcing core members 17, in which multiple reinforcing core members 13, 13... protruding from the upper surface of the top slab 11 are arranged in a rectangular cylindrical shape in plan view, forming a reinforced concrete structure that replaces the conventional RC structure.

[0050] Here, the term "reinforced concrete structure" includes not only RC structures that use reinforcing core materials 13,13… instead of general bar-shaped reinforcing bars, but also RC structures that use reinforcing core materials 13,13… in combination with bar-shaped reinforcing bars. Furthermore, in this invention, bar-shaped reinforcing bars may be used in combination depending on the shape of the structure to be manufactured and the construction conditions.

[0051] Furthermore, in the pier structure 1, since it is subjected to repeated loading during earthquakes, it is required to have high ductility and toughness. In other words, if shear failure occurs first, there is a risk of rapid collapse, so the arrangement of reinforcing core members 13, 13... is designed so that bending failure occurs first in order to give the bridge pier body 12 toughness.

[0052] In this bridge truss 12, a concrete cover of a predetermined thickness is placed on the outside of the reinforcing core members 13, 13…, and spalling of the concrete cover is prevented by restraining it with multiple stirrups and intermediate stirrups 18, 18… that are placed vertically at intervals along the outside of the group of reinforcing core members 17.

[0053] As shown in Figure 5, the tensile reinforcing members 3,3... and reinforcing core members 13,13... each comprise a thin, flat web portion 4, thin, flat flange portions 5,5 extending from both sides of the web portion 4 in directions intersecting the front and back surfaces, and a rod-shaped adhesion strengthening means 6 that strengthens the adhesion between the web portion 4 and the concrete 2.

[0054] The web portion 4 is formed in an elongated, flat shape with a certain length L that satisfies the effective anchorage length with the concrete, for example, a length of six times or more the width H of the web portion 4, and flange portions 5, 5 are formed integrally with both sides thereof.

[0055] The flange portions 5,5 extend from the front and back surfaces on both sides of the web portion 4 in directions that intersect with them, and in this embodiment, in directions perpendicular to the front and back surfaces, so that the cross section formed by the flange portions 5,5 and the web portion 4 is I-shaped or H-shaped.

[0056] The effective width b on one side of the flange portion 5,5 is the width over which the compressive force generated by the Poisson effect when a tensile force is applied to the web portion 4 is effectively applied. For example, it is formed to be about twice the plate thickness t2 of the flange portion 5,5.

[0057] Therefore, the flange portion 5 has a width B on one side that is shorter than the width of the web portion 4, and even if it is classified as an H-shaped steel, such as a narrow H-shaped steel, the cross-section is I-shaped.

[0058] In the above-described embodiment, the flange portions 5, 5 were described as having a shape in which they protrude from the front and back sides of the web portion 4, respectively. However, as shown in Figure 5(d), the flange portions 5, 5 may also protrude from only one side, either the front or the back, as in channel steel.

[0059] The adhesion-enhancing means, as shown in Figure 5, comprises a plurality of rod-shaped members 6, 6… protruding from the surface and back surface of the web portion 4 or from the surface having the flange portion 5 as shown in Figure 5(d). These rod-shaped members 6, 6… are embedded in the concrete 2, thereby ensuring a strong bond between the web portion 4 and the concrete 2.

[0060] Each rod-shaped member 6, 6... comprises a round rod-shaped main body 6a whose lower end is fixed to the web portion 4 by welding, and an enlarged diameter portion 6b integrally supported at the head of the main body portion 6a.

[0061] The means of fixing the rod-shaped member 6 is not limited to welding; for example, it may be fitted by drilling a hole in the web portion, or it may be fastened with screws, etc.

[0062] The rod-shaped member 6 is formed to be approximately the same height as the width B on one side of the web portion 4. Note that the height of the rod-shaped member 6 is not limited to this embodiment; it can be any height or a member of a different diameter, taking into account the desired adhesion strength to the concrete and shear force.

[0063] These rod-shaped members 6, 6... can be headed studs available on the market. However, the rod-shaped members 6, 6... may also be so-called headless studs that do not have an enlarged diameter portion 6b at the head.

[0064] Furthermore, the rod-shaped members 6, 6... are not limited to the embodiments described above, and although not specifically shown, they may have recesses for strengthening adhesion formed on their outer surface, like deformed reinforcing bars, or they may have an enlarged diameter portion 6b at the head of the main body portion 6a having recesses for strengthening adhesion. Moreover, the rod-shaped members 6, 6... can be substituted with bolts, screws, etc.

[0065] These rod-shaped members 6, 6... may be arranged in a staggered pattern (aligned arrangement) by shifting the positions of adjacent rod-shaped members 6, 6... in the longitudinal direction of the web portion 4, as shown in Figure 5(b), or they may be arranged in a staggered pattern (staggered arrangement) by shifting the positions of adjacent rod-shaped members 6, 6... in the longitudinal direction of the web portion 4 by a predetermined interval, as shown in Figure 5(c).

[0066] The number of these rod-shaped members 6,6… is determined based on the procedure in the flowchart shown in Figure 6(a). However, due to the Poisson effect of the web portion 4, the distance between the opposing flange portions 5,5 is reduced, causing the flange portions 5,5 to restrain the concrete and bear a portion of the axial yield tensile force, thereby reducing the load on the rod-shaped members 6,6… and thus allowing the number of members to be reduced.

[0067] Specifically, first, a steel material is selected in which the tensile yield strength fym × Am of a single steel material is greater than the tensile yield strength fys × As of the corresponding multiple reinforcing bars (s1), and the tensile yield strength T = fym × Am of the tensile reinforcing members 3,3…3 and reinforcing core materials 13,13… is determined (s2). Here, fys is the tensile yield strength of the reinforcing bar, fym is the tensile yield strength of the steel material, Am is the cross-sectional area of ​​a single steel material, and As is the cross-sectional area of ​​the corresponding multiple reinforcing bars.

[0068] Next, we determine the frictional force T1 = τ × 2b × L × 2 that the flange portions 5,5 can withstand (Note that for the single-sided flange shown in Figure 5(d), T1 = τ × b × L × 2) (s3). Here, τ is the frictional stress acting on the inside of the flange portions 5,5 when the web yields, b is the effective width on one side of the flange portions 5,5, and L is the effective anchorage length of the web portion 4.

[0069] The specific method for calculating the frictional force T1 that the flange portion 5 can withstand will be explained below based on the flowchart shown in Figure 6(b).

[0070] The effective anchoring length L is assumed to be L = 6 × H based on experiments, etc. (s31), and based on this, the effective compressive force Tx due to the Poisson effect when an axial tensile force is applied is calculated from the following equation (s32). Tx=E·ν·εfw·Ae =E·ν·Ae·Ty / (E·Aw) =Ty·ν·Ae / Aw

[0071] Here, E is Young's modulus, ν is Poisson's ratio, εfw is the yield strain of web 4, Ae is the effective anchoring cross-sectional area of ​​web 4 (Ae = t1 × L), Aw is the cross-sectional area of ​​web 4 (Aw = t1 × H), and Ty is the yield tensile force of the web.

[0072] Next, based on the effective compressive force Tx and empirical rules obtained from experiments, we assume that the effective width b on one side of the flange portion 5,5 when the effective compressive force is applied is b = 2 × t2 (s33). Note that t2 is the plate thickness of the flange portion 5.

[0073] Then, the compressive stress σ = Tx / (b × L × 2) acting from the opposing flange portions 5,5 toward the inner concrete is calculated, and the frictional stress τ = σ × μ acting on the inside of the flange portions 5,5 at web yielding is calculated (s34). μ is the coefficient of friction between the concrete and the steel.

[0074] Following the above procedure, the frictional force T1 = τ × 2b × L × 2 acting between the flange portions 5,5 and the concrete 2 is determined.

[0075] Then, based on the axial yield tensile force T of the entire tensile reinforcing members 3,3…3 and the entire reinforcing core material 13,13… obtained through the above procedure, and the frictional force T1 that the flange portion 5 can bear, the shear force T2 = T - T1 that the rod-shaped members 6,6… should bear is calculated (s4).

[0076] Finally, the number and arrangement of the rod-shaped members 6,6... are determined based on the shear force T2 that each rod-shaped member 6,6... should bear (s5).

[0077] The number and arrangement of the rod-shaped members 6,6… can be determined based on general design methods using headed studs as described in the Composite Structure Standard Specifications and the Road Bridge Specifications.

[0078] As shown in Figures 1 to 3, each of the tensile reinforcing members 3, 3... and reinforcing core members 13, 13... configured in this way is placed within the concrete constituting the top slab 11 and the bridge truss body 12, with its weak axis facing the direction in which the main bending moment assumed in the design acts.

[0079] In other words, in the top slab 11, if the strong axis side of the tensile reinforcing members 3,3…3 is positioned facing the upper and lower surfaces of the top slab 11 (hereinafter referred to as the concrete surface) where the main bending moment assumed in the design of the top slab 11 acts, the effective height of the cross-section will be reduced, similar to the SRC structure. Therefore, the members are positioned with the weak axis side facing the concrete surface, i.e., parallel to the web portion 4 and the concrete surface, and are embedded with their longitudinal direction facing the same direction as conventional reinforcing bars 22,22…

[0080] On the other hand, in the bridge truss body 12, if the reinforcing core members 13, 13… are positioned with their strong axis facing the outer surface of the bridge truss body 12 (hereinafter referred to as the concrete surface) where the main bending moment assumed in the design of the bridge truss body 12 acts, the effective height of the cross-section will be reduced, similar to the SRC structure. Therefore, they are positioned with their weak axis facing the concrete surface, that is, parallel to the web portion 4 and the concrete surface, and are embedded with their longitudinal direction facing the same direction as conventional reinforcing bars 22, 22….

[0081] The pier structure 1 configured in this way can replace multiple reinforcing bars in a conventional pier with a single tensile reinforcing member 3,3...3 and reinforcing core material 13,13..., and can achieve performance equivalent to or better than a conventional reinforced concrete pier with fewer tensile reinforcing members 3,3... and reinforcing core material 13,13....

[0082] The following describes the results of alternating load experiments on column members that mimic this bridge pier structure 1.

[0083] In this alternating load experiment, as shown in Figure 7, repeated loads P, such as seismic inertia, were applied to a test specimen 20 that mimicked the bridge pier structure 1 of the present invention and a test specimen 21 that mimicked a conventional reinforced concrete bridge pier, from the upper side of the test specimens using a loading device 22 such as a hydraulic cylinder. The load-bearing capacity and plasticity ratio were measured, and the crack dispersion and damage characteristics of the concrete were confirmed.

[0084] Figure 8 shows the load-displacement relationship between the two test specimens.

[0085] In the conventional reinforced concrete test specimen 21, the load decreases significantly in the latter half of the step, whereas the test specimen 20 having the structure of the present invention shows ductile strength.

[0086] Furthermore, comparing the damage status in the photographs shown in Figure 9, it was confirmed that in the conventional reinforced concrete test specimen, severe damage occurred at the base of the column at 10δy, with the main reinforcement buckling and a large amount of concrete spalling. However, in the structure according to the present invention, the reinforcing core members 13, 13… were less prone to buckling, and spalling of the cover concrete was reduced.

[0087] Furthermore, in this pier structure 1, reinforcing core members 13, 13… are arranged across the top slab 11 and the pier body 12, and since the reinforcing core members 13, 13… are made of I-beams (H-beams) which are less prone to buckling than conventional bar-shaped reinforcement, the resistance to the moment acting on the plastic hinge portion of the pier body 12 is also strong, making it possible to widen the spacing between the stirrups and intermediate stirrups 18, 18… that restrain the reinforcing core members 13, 13… in the plastic hinge portion compared to conventional structures. Note that a plastic hinge portion refers to a part that has plasticized beyond its yield strength when repeated loads are applied to the pier due to earthquakes, etc., and has lost rotational rigidity like a hinge.

[0088] Furthermore, the spacing between the stirrups and intermediate stirrups 18, 18… that restrain the group of reinforcing core members 13, 13… at the top of the bridge truss body 12, where the aforementioned moment does not act significantly, can be made even wider than near the plastic hinge, thereby reducing the labor required for construction.

[0089] In the above embodiment, an example was described in which a rod-shaped member 6 was used as an adhesion-enhancing means. However, the form of the adhesion-enhancing means is not limited to this. For example, protrusions of a shape other than a rod may be provided on the surface and / or back surface of the web portion 4, or rod-shaped members 6 with different diameters and shapes may be used on the surface and back surface of the web portion 4.

[0090] Furthermore, to improve concrete filling properties and adhesion, the web portion 4 of the tensile reinforcement member 3 may be formed with through holes (generally called a perforated dowel).

[0091] Furthermore, in the above-described embodiment, we explained the case where the web portion 4 is positioned parallel to the concrete surface (hereinafter referred to as the "concrete surface") of the top plate 11, with respect to the weak axis side, i.e., the web portion 4 and the concrete surface. However, prioritizing the filling of the concrete, the tensile reinforcing members 3, 3… may also be positioned with their strong axis sides facing the upper and lower surfaces (hereinafter referred to as the "concrete surface") of the top plate 11.

[0092] Furthermore, the embodiments of the reinforcing core members 13, 13… are not limited to the above-described embodiments. For example, the reinforcing core members 13, 13… may be composed of two types of members: a core member for the plastic hinge portion applied to the plastic hinge portion of the bridge truss body 12, and a thin-walled core member applied to portions other than the plastic hinge portion. The web portion and flange portion of the thin-walled core member may be formed to be thinner than the web portion and flange portion of the core member for the plastic hinge portion.

[0093] For example, if the plastic hinge portion of the bridge truss body 12 extends from the top plate 11 to a predetermined height, and the portion above that is not the plastic hinge portion, the portion from the top plate 11 to the upper end of the plastic hinge portion is designated as the core member for the plastic hinge, and a thin-walled core member is joined to the upper end of the core member for the plastic hinge to form a reinforcing core material 13.

[0094] In this case, while ensuring the strength of the plastic hinge section where the greatest bending moment and shear force are applied, material costs can be reduced by using thinner core members in the other parts.

[0095] Furthermore, although the above embodiment described a case in which the top plate 11 also uses the same material as the core member, it is also possible to make the top plate 11 a reinforced concrete structure using general bar-shaped reinforcing bars. [Explanation of Symbols]

[0096] 1. Bridge pier structure 2 Ground 3. Tensile reinforcing members 4. Web Department 5. Flange section 6. Rod-shaped member 8 Connecting members 9. Group of tensile reinforcing members 10 Colony connection member 11 Top version 12 Bridge script type 13 Reinforcement core material 14 Steel pipe sheet pile well foundation 15 Steel pipe sheet piles 16. Tensile reinforcement member group unit 17. Reinforcement core material group 18 Stirring bars and intermediate stirrup bars

Claims

1. In a bridge pier structure comprising a concrete top plate in which horizontal tensile reinforcing members are embedded in multiple vertically arranged layers, a concrete bridge slab erected on the top plate, and a plurality of vertically oriented reinforcing core members embedded in the top plate and the bridge slab, The reinforcing core material comprises an elongated flat web portion, flange portions extending from both sides of the web portion in a direction intersecting the surface and / or back surface of the web portion, and adhesion strengthening means for bonding the web portion to the top plate and the concrete constituting the bridge truss body. The pier structure is characterized in that the reinforcing core material is positioned with its weak axis facing the direction in which the main bending moment assumed in the design of the pier body acts.

2. The pier structure according to claim 1, wherein the reinforcing core material is composed of two types of members: a core member for the plastic hinge portion applied to the plastic hinge portion of the pier truss and a thin-walled core member applied to portions other than the plastic hinge portion, and the web portion and flange portion of the thin-walled core member are formed to be thinner than the web portion and flange portion of the core member for the plastic hinge portion.

3. The bridge pier structure according to claim 1 or 2, wherein the adhesion strengthening means comprises a plurality of rod-shaped members protruding from the surface and / or back surface of the web portion.

4. The flange portion is formed to a width that allows the compressive force generated by the Poisson effect of the web portion to act effectively. The number of rod-shaped members is such that they can bear the shear force obtained by subtracting the burden due to the frictional force generated between the flange portion and the concrete due to the Poisson effect of the web portion from the axial yield tensile force of the reinforcing core material.

5. The tensile reinforcing member comprises an elongated flat web portion, flange portions extending from both sides of the web portion in a direction intersecting the surface and / or back surface of the web portion, and adhesion strengthening means for adhering the web portion to the concrete constituting the top plate, as described in any one of claims 1 to 4.

6. The bridge pier structure according to claim 5, comprising a group of tensile reinforcing members, wherein a plurality of the tensile reinforcing members, which are arranged at horizontal intervals from one another, are connected by a connecting member.

7. The bridge pier structure according to claim 6, wherein a plurality of the tensile reinforcing member groups are arranged with vertical spacing between them, and the groups of reinforcing members are connected by a group connecting member to form a unit.

8. The pier structure according to any one of claims 5 to 7, wherein the tensile reinforcing member is positioned in the top plate with its weak axis facing the direction in which the main bending moment assumed in the design of the top plate acts.

9. The pier structure according to claim 8, wherein the tensile reinforcing member has a through hole formed that penetrates the web portion.

10. The pier structure according to any one of claims 5 to 7, wherein the tensile reinforcing member is positioned in the top plate with its strong axis facing the direction in which the main bending moment assumed in the design of the top plate acts.

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