Design method of column-beam joint portion, and rigid-frame viaduct

Abstract

To provide a design method of a column-beam joint portion in a precast construction method that can evaluate seismic performance using an amount of displacement of a column-beam joint portion at a point M as a threshold.SOLUTION: In a design method of a column-beam joint portion in a precast rigid-frame viaduct, a vertical beam joint portion 40 is formed by pouring concrete into a lap joint portion in which band-shaped reinforcing bars 41 are arranged by being wrapped around column-side closing reinforcing bars 11 of column members 10 and beam-side closing reinforcing bars 21 of vertical beam members 20 which are overlapped in a width direction Y, and bearing pressure reinforcing bars 42 are arranged at corners of the column-side closing reinforcing bars 11 and corners of the beam-side closing reinforcing bars 21. In order to calculate a displacement amount of the vertical beam joint portion 40 that can maintain a maximum bending moment Mm, a plastic hinge rotation angle θpm of the vertical beam joint portion 40 is calculated using the following formula.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to a method for designing a column-beam joint that joins a column member and a beam member in a rigid-frame concrete structure constructed using a precast construction method, and to a rigid-frame viaduct in which the column-beam joint is designed using this design method. [Background technology]

[0002] One example of a concrete structure, such as a rigid-frame viaduct, is a concrete structure constructed by a cast-in-place method in which concrete is poured into a formwork assembled at the construction site. Furthermore, in recent years, a precast construction method has been proposed in which concrete column members and concrete beam members are joined at the construction site in order to improve work efficiency at the construction site.

[0003] Specifically, in the precast construction method, the column and beam members are joined by pouring concrete into the lap joint, which is made by overlapping the column-side closing reinforcing bars of a closed shape protruding from the surface of the column member and the beam-side closing reinforcing bars of a closed shape protruding from the surface of the beam member in a staggered manner along a predetermined direction, to form a column-beam joint (see Patent Document 1).

[0004] Incidentally, when designing concrete structures constructed using the cast-in-place method, the concrete structure is replaced with a simple model such as a rod member, and nonlinear analysis is performed to calculate the displacement of the plastic hinge section and evaluate its seismic performance.

[0005] For example, when evaluating the seismic performance of a cast-in-place concrete structure, first calculate the maximum bending moment from the desired performance requirements, and then determine the curvature φ of the plastic hinge part that can maintain the calculated maximum bending moment. m (hereinafter referred to as point M) is the plastic hinge rotation angle θ pm Calculated based on the following.

[0006] And the curvature of the plastic hinge part at point M is φ mis set as the threshold value, and the curvature of the plastic hinge part at the time of load input assuming earthquake motion is the curvature of the plastic hinge part at point M, φ m If the result is below 0.01, the cast-in-place concrete structure is judged to satisfy the desired seismic performance.

[0007] However, the plastic hinge rotation angle θ at point M mentioned above pm and the curvature of the plastic hinge part φ m The conventional formula for calculating this is based on the assumption that concrete structures are constructed using the cast-in-place method, and is therefore not suitable for precast concrete structures, which have different deformation and damage patterns than cast-in-place concrete structures.

[0008] For this reason, when designing concrete structures constructed using precast construction methods, there was a need to establish a formula for calculating the amount of displacement suitable for column-beam joints, and to evaluate seismic performance using the amount of displacement of the column-beam joint at point M as a threshold, just like with cast-in-place concrete structures. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2020-90884 Summary of the Invention [Problem to be solved by the invention]

[0010] In view of the above-mentioned problems, the present invention aims to provide a design method for a column-beam joint in a precast construction method that can evaluate seismic performance using the displacement of the column-beam joint at point M as a threshold value, and a rigid-frame viaduct whose column-beam joint is designed using this design method. [Means for solving the problem]

[0011] This invention is a design method for a column-beam joint in a rigid-frame concrete structure having a column-beam joint formed by joining column members and beam members by a precast construction method, wherein the column-beam joint is configured by overlapping, in the predetermined direction, column-side closure reinforcing bars of a closed shape protruding from the surface of the column member at a predetermined interval in a predetermined direction and beam-side closure reinforcing bars of a closed shape protruding from the surface of the beam member at a predetermined interval in the predetermined direction, and the column-side closure reinforcing bars and the beam-side closure reinforcing bars of a closed shape protruding from the surface of the beam member at a predetermined interval in the predetermined direction, and wrapping band-shaped reinforcing bars around the overlapped column-side closure reinforcing bars and the beam-side closure reinforcing bars along the predetermined direction, and pouring concrete into lap joints where bearing reinforcement reinforcing bars are arranged along the predetermined direction at corners of the column-side closure reinforcing bars and corners of the beam-side closure reinforcing bars, and pm The ratio of the reinforcement bars in the beam-column joint p w (%) and tensile reinforcement ratio p t The calculation is performed using the following formula (%):

[0012]

number

[0013] According to this invention, in the design of a concrete structure constructed by a precast construction method, the plastic hinge rotation angle θ of the column-beam joint at point M is pmTherefore, the design method for the beam-column joint can be implemented by using the plastic hinge rotation angle θ of the beam-column joint calculated by the above formula. pm Using this, the displacement of the beam-column joint at point M can be easily calculated.

[0014] This allows the design method for column-beam joints in precast construction, and rigid-frame viaducts whose column-beam joints are designed using this design method, to evaluate their seismic performance using the displacement of the column-beam joint at point M as a threshold value.

[0015] Furthermore, compared to when a concrete structure is designed using a threshold value of the displacement of the column-beam joint at the yield bending moment that is smaller than the displacement of the column-beam joint at point M calculated using conventional calculation formulas, the cross-sectional areas of the column members and the beam members can be made smaller. Therefore, the design method for column-beam joints using the precast construction method, and rigid-frame viaducts whose column-beam joints are designed using this design method, can suppress the increase in size of the column members and beam members and satisfy the desired seismic resistance performance.

[0016] In one aspect of the present invention, the curvature φ of the beam-column joint that can maintain the maximum bending moment is m The plastic hinge rotation angle θ pm , and the equivalent plastic hinge length L p It may be calculated using the following formula:

[0017]

number

[0018] Therefore, the design method for the column-beam joint is to use the curvature φ of the column-beam joint at point M in a precast concrete structure. m It is possible to easily evaluate seismic performance using this as a threshold value.

[0019] In another aspect of the present invention, when a predetermined input assuming earthquake motion is applied to the concrete structure, the curvature of the column-beam joint due to bending deformation is set to a value equal to the curvature φ of the column-beam joint that can maintain the maximum bending moment. m The beam-column joint may be designed so that the This configuration makes it possible to easily design a concrete structure that satisfies both the desired performance requirements and earthquake resistance. [Effects of the Invention]

[0020] The present invention provides a design method for column-beam joints in precast construction that can evaluate seismic performance using the displacement of the column-beam joint at point M as a threshold value, and a rigid-frame viaduct whose column-beam joints are designed using this design method. [Brief explanation of the drawings]

[0021] [Figure 1] A schematic diagram illustrating the outline of a rigid-frame viaduct. [Figure 2] FIG. [Figure 3] FIG. 10 is a front view showing the appearance of the vertical beam joint as viewed from the width direction. [Figure 4] FIG. 4 is an exploded perspective view showing the appearance of a column-beam joint in a disassembled state. [Figure 5] FIG. 2 is a plan view showing the appearance of a vertical beam joint in plan view. [Figure 6] FIG. 10 is an explanatory diagram illustrating the assembly process of the vertical beam member. [Figure 7] A diagram showing the relationship between bending moment and curvature using a tetralinear model. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a design method for a beam-column joint in a rigid-frame viaduct 1, which is a reinforced concrete structure constructed by a precast construction method, will be described with reference to FIGS.

[0023] Note that Figure 1 shows a schematic diagram illustrating the rigid-frame viaduct 1, Figure 2 shows an external perspective view of the column-beam joint, Figure 3 shows a front view of the vertical beam joint 40 as seen from the width direction Y, Figure 4 shows an exploded perspective view of the column-beam joint, and Figure 5 shows a plan view of the vertical beam joint 40.

[0024] Also, Figure 6 is an explanatory diagram explaining the assembly process of the vertical beam member 20, Figure 6(a) shows an explanatory diagram explaining the state of the vertical beam member 20 before assembly, Figure 6(b) shows an explanatory diagram explaining the state of the vertical beam member 20 placed on the bracket B, and Figure 7 shows a diagram showing the relationship between bending moment and curvature.

[0025] In addition, for clarity of illustration, the outer shape of the column-beam joint is shown by a two-dot chain line in Figure 2, the outer shape of the vertical beam joint 40 and the band-shaped steel bars 41 are shown by two-dot chain lines in Figures 3 and 5, and the bearing reinforcement steel bars 42 are not shown in Figure 5.

[0026] In addition, the arrow X in the figure indicates the extension direction of the rigid-frame viaduct 1 (hereinafter referred to as the extension direction X), and the arrow Y in the figure indicates the width direction of the rigid-frame viaduct 1 (hereinafter referred to as the width direction Y), which is approximately perpendicular to the extension direction X in a planar view.

[0027] As shown in FIG. 1, the rigid-frame viaduct 1 of this embodiment is a reinforced concrete structure composed of a plurality of column members 10 extending in the vertical direction, a plurality of longitudinal beam members 20 extending in the extension direction X, and a plurality of transverse beam members 30 extending in the width direction Y.

[0028] Specifically, the rigid-frame viaduct 1 has a pair of column members 10 arranged opposite each other at a predetermined interval in the width direction Y, and multiple column members 10 arranged at a predetermined interval in the extension direction X, with vertical beam members 20 spanning the column members 10 facing each other in the extension direction X, and horizontal beam members 30 spanning the column members 10 facing each other in the width direction Y.

[0029] Furthermore, as shown in Figures 1 to 3, in the rigid-frame viaduct 1, the column members 10 and the vertical beam members 20 are joined by vertical beam joints 40 whose main reinforcements are the column-side closing reinforcing bars 11 of the column members 10 and the beam-side closing reinforcing bars 21 of the vertical beam members 20, which will be described later.

[0030] In addition, in the rigid-frame viaduct 1, the column members 10 and the cross beam members 30 are joined by cross beam joints 50, whose main reinforcements are the column-side closing reinforcing bars 11 of the column members 10 and the beam-side closing reinforcing bars 31 of the cross beam members 30, as described below.

[0031] More specifically, as shown in FIG. 1, the pillar member 10 is a cast-in-place or precast reinforced concrete member, and is formed into a pillar-like body extending in the vertical direction and having a substantially square cross section.

[0032] In this column member 10, of the four side surfaces that are approximately parallel in the vertical direction, the upper part of three side surfaces 10a that face adjacent column members 10 has a plurality of column-side closing reinforcing bars 11 that protrude toward the opposing column member 10, as shown in Figure 4.

[0033] As shown in Figures 3 and 4, this column-side closing reinforcing bar 11 protrudes in a direction perpendicular to the side surface 10a and is composed of a U-shaped outer reinforcing bar 12 and an inner reinforcing bar 13 that are open on the side surface 10a side so as to form a closed shape with the side surface 10a.

[0034] Specifically, the outer reinforcing bar 12 is formed in a U-shape by bending the tip extending in one direction perpendicular to the side surface 10a away from the side surface 10a downward, and then bending it back in the other direction perpendicular to the side surface 10a.

[0035] On the other hand, the inner reinforcing bar 13 is formed in a U-shape that is slightly smaller than and similar to the outer reinforcing bar 12. The inner reinforcing bar 13 is disposed at approximately the same position as the outer reinforcing bar 12 in a direction that is approximately perpendicular to the direction of the side surface 10a in a plan view.

[0036] The two upper and lower bent portions of the outer reinforcing bar 12 are corner portions 12a of the outer reinforcing bar 12, and the two upper and lower bent portions of the inner reinforcing bar 13 are corner portions 13a of the inner reinforcing bar 13 (see FIG. 3).

[0037] As shown in FIG. 5, such column-side closing bars 11 are arranged at predetermined intervals in the width direction Y on the side surface 10a facing the extension direction X, and the column-side closing bars 11 on the side surface 10a facing the width direction Y are arranged at predetermined intervals in the extension direction X.

[0038] As shown in FIG. 1, the vertical beam members 20 are precast reinforced concrete members, and are formed into columnar bodies extending in the extension direction X and having a substantially square cross section. As shown in Figures 2 and 3, this vertical beam member 20 is formed with a length in the extension direction X that is shorter than the distance between the opposing pillar members 10 in the extension direction X, so that the end face 20a in the extension direction X and the side face 10a of the pillar member 10 face each other at a predetermined distance in the extension direction X.

[0039] Furthermore, as shown in Figure 4, on the end face 20a of the vertical beam member 20, multiple beam side closing bars 21 are provided at predetermined intervals in the width direction Y, protruding in the extension direction X toward the opposing column member 10. Specifically, as shown in Figures 3 and 4, the beam side closing reinforcing bar 21 protrudes in the extension direction X and is composed of a U-shaped outer reinforcing bar 22 and an inner reinforcing bar 23 that are open on the end face 20a side so as to form a closed shape with the end face 20a.

[0040] The outer reinforcing bar 22 is formed in a U-shape by bending the tip extending in one direction of the extension direction X away from the end face 20a downward, and then bending it back in the other direction of the extension direction X and extending toward the end face 20a.

[0041] On the other hand, the inner reinforcing bars 23 are approximately similar in shape to but slightly smaller than the outer reinforcing bars 22, and are formed in a U-shape with approximately the same vertical length as the inner reinforcing bars 13 of the column member 10. The inner reinforcing bars 23 are arranged at approximately the same position as the outer reinforcing bars 22 in the width direction Y.

[0042] The two upper and lower bent portions of the outer reinforcing bar 22 are corner portions 22a of the outer reinforcing bar 22, and the two upper and lower bent portions of the inner reinforcing bar 23 are corner portions 23a of the inner reinforcing bar 23 (see FIG. 3).

[0043] As shown in Figure 5, such beam-side closing reinforcing bars 21 are arranged at a predetermined interval in the width direction Y so that they are staggered relative to the column-side closing reinforcing bars 11 when the side surface 10a of the column member 10 faces the end surface 20a of the vertical beam member 20.

[0044] More specifically, the beam-side closing rebar 21 is spaced apart in the width direction Y at approximately the same interval as the column-side closing rebar 11 of the column member 10, and is positioned offset in the width direction Y from the column-side closing rebar 11 by approximately the rebar diameter.

[0045] Therefore, when the side surface 10a of the column member 10 faces the end surface 20a of the vertical beam member 20, the multiple beam side closing reinforcing bars 21 are arranged close to the column side closing reinforcing bars 11 so as to overlap each other in the width direction Y, and the beam side closing reinforcing bars 21 and column side closing reinforcing bars 11 that are close to each other in the width direction Y are arranged at a predetermined interval along the width direction Y.

[0046] As shown in Figure 3, the column-side closing reinforcing bar 11 and the beam-side closing reinforcing bar 21 are formed so that the joint length F between the inner reinforcing bar 13 of the column-side closing reinforcing bar 11 and the inner reinforcing bar 23 of the beam-side closing reinforcing bar 21 is more than twice the reinforcing bar diameter.

[0047] As shown in FIG. 1, the cross beam members 30 are precast reinforced concrete members, and are formed into columnar bodies extending in the width direction Y and having a substantially square cross section. As shown in Figure 2, this cross beam member 30 is formed with a length in the width direction Y that is shorter than the spacing between opposing pillar members 10 in the width direction Y, so that the end face 30a in the width direction Y and the side face 10a of the pillar member 10 face each other at a predetermined distance in the width direction Y.

[0048] Furthermore, as shown in Figure 4, on the end face 30a of the cross beam member 30, multiple beam side closing reinforcements 31 are provided at predetermined intervals in the extension direction X, protruding in the width direction Y toward the opposing column member 10.

[0049] As shown in Figure 4, this beam side closing reinforcing bar 31 protrudes toward the width direction Y and is composed of a U-shaped outer reinforcing bar 32 and an inner reinforcing bar 33 with an open end face 30a side so as to form a closed shape with the end face 30a. The beam-side closing reinforcing bars 31 of the horizontal beam member 30 have substantially the same configuration as the beam-side closing reinforcing bars 21 of the vertical beam member 20, except for the protruding direction, and therefore detailed description thereof will be omitted.

[0050] In addition, the vertical beam joint 40, which is the column-beam joint between the column member 10 and the vertical beam member 20, is a cast-in-place reinforced concrete section with column-side closing reinforcing bars 11 and beam-side closing reinforcing bars 21 as the main reinforcement, as shown in Figure 2, and is formed between the side surface 10a of the column member 10 and the end face 20a of the vertical beam member 20.

[0051] As shown in Figures 2 and 3, this vertical beam joint 40 is formed by pouring concrete into a lap joint (symbol omitted) consisting of the above-mentioned column-side closing reinforcing bars 11 and beam-side closing reinforcing bars 21, five strip-shaped reinforcing bars 41 arranged at predetermined intervals in the extension direction X, and eight bearing reinforcement reinforcing bars 42 extending in the width direction Y.

[0052] Specifically, as shown in Figures 2 and 3, the strip-shaped steel bar 41 is wrapped around the column-side closing steel bars 11 and the beam-side closing steel bars 21 stacked in the width direction Y so as to integrally surround them, and is joined to the column-side closing steel bars 11 and the beam-side closing steel bars 21.

[0053] On the other hand, as shown in Figures 2 and 3, the bearing reinforcement steel bars 42 are steel bars extending in the width direction Y, and are joined to the column-side closing steel bars 11 and the beam-side closing steel bars 21 that are overlapped in the extension direction X, connecting the column-side closing steel bars 11 and the beam-side closing steel bars 21 in the width direction Y.

[0054] More specifically, of the eight bearing reinforcement bars 42, four bearing reinforcement bars 42 are arranged at the upper and lower corner portions 12a of the outer reinforcement bars 12 of the column-side closing reinforcement bars 11 and at the upper and lower corner portions 13a of the inner reinforcement bars 13 of the column-side closing reinforcement bars 11, as shown in Figure 3, and connect the column-side closing reinforcement bars 11 and the beam-side closing reinforcement bars 21 in the width direction Y.

[0055] On the other hand, the other four bearing reinforcement bars 42 are arranged at the upper and lower corner portions 22a of the outer reinforcement bars 22 of the beam side closing reinforcement bars 21, and at the upper and lower corner portions 23a of the inner reinforcement bars 23 of the beam side closing reinforcement bars 21, as shown in Figure 3, and connect the column side closing reinforcement bars 11 and the beam side closing reinforcement bars 21 in the width direction Y.

[0056] In a method of constructing such a vertical beam joint 40, for example, as shown in FIG. 6, the vertical beam member 20 extending in the extension direction X is placed from above on a bracket B attached to the side surface 10a of the pillar member 10. In this case, the method of constructing the vertical beam joint 40 is to place the vertical beam member 20 on the bracket B so that the column side closing reinforcing bars 11 and the beam side closing reinforcing bars 21 are positioned alternately in the width direction Y.

[0057] Furthermore, the method of constructing the vertical beam joint 40 is to arrange the strip-shaped steel bars 41 and the pressure-reinforcement steel bars 42 to form a lap joint, and then assemble a formwork for pouring concrete between the column member 10 and the vertical beam member 20.

[0058] The method of constructing the vertical beam joint 40 is to pour concrete inside the formwork, and after the concrete has hardened, remove the bracket B and the formwork to construct the vertical beam joint 40 and integrate the column member 10 and the vertical beam member 20. In the method for constructing the vertical beam joint 40, the vertical beam joint 40 may be constructed without removing the bracket B.

[0059] In addition, the cross beam joint 50, which is the column-beam joint between the column member 10 and the cross beam member 30, is a cast-in-place reinforced concrete section with column-side closing reinforcing bars 11 and beam-side closing reinforcing bars 31 as the main reinforcement, and is formed between the side surface 10a of the column member 10 and the end face 30a of the cross beam member 30.

[0060] As shown in Figure 2, this cross beam joint 50 is formed by pouring concrete into a lap joint (symbol omitted) consisting of the above-mentioned column-side closing reinforcing bars 11 and beam-side closing reinforcing bars 31, five strip-shaped reinforcing bars 51 arranged at predetermined intervals in the width direction Y, and eight bearing reinforcement reinforcing bars 52 extending in the extension direction X.

[0061] The horizontal beam joint 50 has the same configuration and is constructed by the same construction method as the vertical beam joint 40 described above, and therefore a detailed description thereof will be omitted. The vertical beam joint 40 and the horizontal beam joint 50 configured as described above are designed by a design method for beam-column joints, which will be described later, so as to satisfy the desired required performance and earthquake resistance performance.

[0062] Next, a design method for the column-beam joint in the rigid-frame viaduct 1 of this embodiment constructed by the above-mentioned precast construction method will be described with reference to FIG. Since the vertical beam joints 40 and the horizontal beam joints 50 are designed using the same design method, in this embodiment, the vertical beam joints 40 will be described and a description of the horizontal beam joints 50 will be omitted.

[0063] First, as a design method for rigid-frame viaducts, the maximum bending moment M is determined in accordance with the "Design Standards for Railway Structures, etc. (Concrete Structures)" issued by the Director-General of the Railway Bureau of the Ministry of Land, Infrastructure, Transport and Tourism. m There is a method to calculate the displacement of the plastic hinge part that can maintain the above.

[0064] In detail, the conventional design method based on the "Design Standard for Railway Structures, etc. (Concrete Structures)" calculates the bending moment M of the plastic hinge part based on the load acting on the rigid-frame viaduct and its own weight, and calculates the bending moment M of the plastic hinge part when the compressive strain of the concrete reaches the ultimate strain as the maximum bending moment M. m Let's say.

[0065] Furthermore, the conventional design method is to limit the maximum bending moment M m The curvature φ of the plastic hinge part that can maintain m (hereinafter referred to as point M) is the plastic hinge rotation angle θ pm Calculated based on the following. In the conventional design method, the curvature φ of the plastic hinge part at point M is m When the input load assuming a level 2 earthquake motion is applied to the rigid-frame viaduct, the curvature φ of the plastic hinge part due to bending deformation is calculated as follows: m The plastic hinge part is designed to be less than

[0066] Since this conventional design method is intended for rigid-frame viaducts constructed using the cast-in-place method, it was necessary to verify whether it was suitable for the rigid-frame viaduct 1 of this embodiment, which is constructed using the precast method, which has a different joint structure between the column members 10 and the beam members (longitudinal beam members 20 and transverse beam members 30).

[0067] In response to this, the applicant conducted various experiments and verifications, and as a result, the plastic hinge rotation angle θ of the longitudinal beam joint 40 at point M calculated by applying the conventional design method to the rigid-frame viaduct 1 constructed by the precast construction method was pm and the plastic hinge rotation angle θ of the vertical beam joint 40 at point M obtained in the experiment. pm It was confirmed that there was a discrepancy between the two.

[0068] Therefore, the curvature φ of the vertical beam joint 40 at point M calculated using the conventional design method ms and the curvature φ of the vertical beam joint 40 at point M obtained in the experiment. meWhen comparing the curvature φ of the vertical beam joint 40 at point M calculated using the conventional design method with the tetra-linear model in Figure 7, ms In contrast, the curvature φ of the vertical beam joint 40 at point M obtained in the experiment me was found to be smaller.

[0069] In this case, the curvature φ of the plastic hinge part due to the input load assuming a level 2 earthquake motion is calculated by applying the conventional design method to the curvature φ of the vertical beam joint 40 at point M. ms Even if the resistance is below this level, there is a risk that the actual rigid-frame viaduct will not meet the seismic performance requirements.

[0070] Therefore, the applicant conducted various experiments and repeated verifications to arrive at a design method for beam-column joints suitable for rigid-frame viaducts 1 constructed using precast construction methods. Specifically, in the design method for a column-beam joint in this embodiment, the ratio of the strip reinforcement 41 to the cross section of the vertical beam joint 40 is defined as the strip reinforcement ratio p w (%), and the ratio of the tension reinforcement to the effective cross-sectional area of ​​the vertical beam joint 40 is the tension reinforcement ratio p t (%), the plastic hinge rotation angle θ of the vertical beam joint 40 at point M pm is calculated using the following formula 1.

[0071]

number

[0072]

number

[0073] In the design method for the beam-column joint in this embodiment, the maximum bending moment M m is calculated in accordance with the "Design Standards for Railway Structures, etc. (Concrete Structures)."

[0074] As a result, the design method for the column-beam joint in the rigid-frame viaduct 1 constructed by the precast construction method is the same as the conventional design method, and the curvature φ of the column-beam joint (longitudinal beam joint 40) at point M is m It is possible to evaluate seismic performance using this as a threshold.

[0075] As described above, the rigid-frame viaduct 1 of this embodiment is a concrete structure having vertical beam joints 40 (column-beam joints) formed by joining column members 10 and vertical beam members 20 using a precast construction method, and cross beam joints 50 (column-beam joints) formed by joining column members 10 and cross beam members 30 using a precast construction method.

[0076] The vertical beam joint 40 of this rigid-frame viaduct 1 is formed by overlapping, in the width direction Y, closed-shaped column-side closing reinforcing bars 11 that protrude from the side surface 10a of the column member 10 at a predetermined interval in the width direction Y, and closed-shaped beam-side closing reinforcing bars 21 that protrude from the end surface 20a of the vertical beam member 20 at a predetermined interval in the width direction Y, and wrapping strip-shaped reinforcing bars 41 around the overlapped column-side closing reinforcing bars 11 and beam-side closing reinforcing bars 21 along the width direction Y, and pouring concrete into the overlap joint where bearing reinforcement reinforcing bars 42 are arranged along the width direction Y at the corner portions 12a, 13a of the column-side closing reinforcing bars 11 and the corner portions 22a, 23a of the beam-side closing reinforcing bars 21.

[0077] On the other hand, the cross beam joint 50 of the rigid-frame viaduct 1 is formed by overlapping, in the extension direction X, column-side closure reinforcing bars 11 of a closed shape protruding from the side surface 10a of the column member 10 at a predetermined interval in the extension direction X and beam-side closure reinforcing bars 31 of a closed shape protruding from the end surface 30a of the cross beam member 30 at a predetermined interval in the extension direction X, and wrapping strip-shaped reinforcing bars 51 around the overlapped column-side closure reinforcing bars 11 and beam-side closure reinforcing bars 31 along the extension direction X, and pouring concrete into the lap joint where bearing reinforcement reinforcing bars 52 are arranged along the extension direction X at the corner portions 12a, 13a of the column-side closure reinforcing bars 11 and the corner portions (symbols omitted) of the beam-side closure reinforcing bars 31.

[0078] The design method for the column-beam joint in the rigid-frame viaduct 1 of this embodiment is as follows: m In order to calculate the displacement of the column-beam joint that can maintain the above, the plastic hinge rotation angle θ of the column-beam joint (vertical beam joint 40 and horizontal beam joint 50) is calculated. pm The ratio of reinforcement bars in the beam-column joint is p w (%) and tensile reinforcement ratio p t (%) and calculated using the above formula 1. In the rigid-frame viaduct 1 of this embodiment, the longitudinal beam joints 40 and the cross beam joints 50 are designed by the above-described method for designing a beam-column joint.

[0079] According to this configuration, in the design of the rigid-frame viaduct 1 constructed by the precast construction method, the plastic hinge rotation angle θ of the column-beam joint (vertical beam joint 40 and horizontal beam joint 50) at point M is pm A formula for calculating the above can be provided.

[0080] Therefore, the design method for the column-beam joint is to use the plastic hinge rotation angle θ of the column-beam joint calculated by the above formula. pm Using this, the displacement of the column-beam joint (longitudinal beam joint 40 and horizontal beam joint 50) at point M can be easily calculated.

[0081] As a result, the design method for column-beam joints in the precast construction method, and the rigid-frame viaduct 1 whose column-beam joints (vertical beam joints 40 and horizontal beam joints 50) have been designed using this design method, can evaluate the seismic performance using the displacement amount of the column-beam joint at point M as a threshold value.

[0082] Furthermore, if the yield bending moment M is smaller than the displacement of the beam-column joint at point M calculated using the conventional formula, y Compared to when a rigid-frame viaduct is designed using the displacement amount of the column-beam joint in the precast method (see Figure 7) as a threshold, the cross-sectional area of ​​the column members 10 and the cross-sectional area of ​​the beam members (longitudinal beam members 20 and horizontal beam members 30) can be made smaller. Therefore, the design method for column-beam joints using the precast method, and the rigid-frame viaduct 1 in which the column-beam joints (longitudinal beam joints 40 and horizontal beam joints 50) are designed using this design method, can suppress the increase in size of the column members 10 and beam members and satisfy the desired seismic performance.

[0083] In addition, the design method for the beam-column joint in the precast construction method is to limit the maximum bending moment M m The curvature φ of the column-beam joint (vertical beam joint 40 and horizontal beam joint 50) can be maintained. m , the plastic hinge rotation angle θ pm , and the equivalent plastic hinge length L p It is calculated using the above formula 2.

[0084] According to this configuration, the plastic hinge rotation angle θ of the beam-column joint at point M is the same as that of a cast-in-place rigid frame viaduct. pm Using this, the displacement of the beam-column joint at point M can be calculated.

[0085] Therefore, the design method for the column-beam joint is as follows: In the rigid-frame viaduct 1 constructed by the precast method, the curvature φ of the column-beam joint (vertical beam joint 40 and horizontal beam joint 50) at point M is m It is possible to easily evaluate seismic performance using this as a threshold value.

[0086] In addition, the design method for the column-beam joint in the precast construction method is such that when an input load assuming a level 2 earthquake motion is applied to the rigid frame viaduct 1, the curvature φ of the column-beam joint (longitudinal beam joint 40 and horizontal beam joint 50) due to bending deformation is equal to the maximum bending moment M m The curvature φ of the column-beam joint (vertical beam joint 40 and horizontal beam joint 50) can be maintained. m The vertical beam joints 40 and the horizontal beam joints 50 are designed so that the joints are less than the above. According to this configuration, it is possible to easily design a rigid-frame viaduct 1 that satisfies both the desired required performance and earthquake resistance performance.

[0087] In correspondence between the configuration of this invention and the above-mentioned embodiment, The beam members of this invention correspond to the longitudinal beam members 20 and the transverse beam members 30 of the embodiment, Similarly, The column-beam joints correspond to the vertical beam joints 40 and the horizontal beam joints 50, The concrete structure corresponds to the rigid frame viaduct 1, The predetermined direction corresponds to the width direction Y and the stretching direction X, The displacement of the beam joint is determined by the plastic hinge rotation angle θ of the vertical beam joint 40. pm , and the plastic hinge rotation angle θ of the cross beam joint 50 pm corresponds to, The present invention is not limited to the configurations of the above-described embodiments, and many other embodiments can be obtained.

[0088] For example, in the above embodiment, a design method for a beam-column joint in a precast construction method was explained using a rigid-frame viaduct 1, but this is not limited to this, and any appropriate rigid-frame concrete structure constructed using a precast construction method may be used.

[0089] Furthermore, although the rigid-frame viaduct 1 is constructed of column members 10, vertical beam members 20, and horizontal beam members 30, it is not limited to this, and the rigid-frame viaduct may be constructed in any suitable manner as long as it is a rigid-frame structure constructed using a precast construction method.

[0090] In addition, the vertical beam member 20 and the horizontal beam member 30 are placed from above on the bracket B attached to the side surface 10a of the column member 10, and then concrete is poured to construct the vertical beam joint 40 and the horizontal beam joint 50, but this is not limited to this. For example, a platform may be installed at the location where precast vertical beam members 20 and horizontal beam members 30 will be placed, and the vertical beam members 20 and horizontal beam members 30 may be placed on the installed platform from above, and then concrete may be poured to construct the vertical beam joints 40 and horizontal beam joints 50.

[0091] Furthermore, although the column side closing rebar 11 is composed of two rebars, an outer rebar 12 and an inner rebar 13, this is not limitative and, for example, the column side closing rebar 11 may be composed of only the outer rebar 12. In this case, the beam side closing reinforcing bars 21 of the vertical beam members 20 are formed of outer reinforcing bars 22 , and the beam side closing reinforcing bars 31 of the horizontal beam members 30 are formed of outer reinforcing bars 32 .

[0092] Furthermore, among the four side surfaces of the column member 10, the column-side closing rebars 11 are provided on three side surfaces 10a that face adjacent column members 10, but the side surfaces on which the column-side closing rebars 11 are provided are not limited to the above-mentioned three side surfaces 10a as long as they face adjacent column members 10 and are connected via beam members. Furthermore, one or more column-side closing rebars 11 may be provided on one side surface 10a.

[0093] Furthermore, although not mentioned in the above-described embodiment, the column-side closing rebars 11 and the beam-side closing rebars 21, 31 may be set to an appropriate size, shape, number, and rebar diameter according to the structure and size of the rigid-frame viaduct 1, the structure and size of the vertical beam members 20, and the structure and size of the horizontal beam members 30.

[0094] Similarly, the strip-shaped reinforcing bars 41 and bearing reinforcement bars 42 of the vertical beam joints 40, and the strip-shaped reinforcing bars 51 and bearing reinforcement bars 52 of the horizontal beam joints 50 may be set to an appropriate size, shape, number, and reinforcing bar diameter depending on the structure and size of the rigid-frame viaduct 1, the structure and size of the vertical beam members 20, and the structure and size of the horizontal beam members 30. [Explanation of symbols]

[0095] 1...Rahmen viaduct 10...Column member 11...Column side closing rebar 12a, 13a... Corner 20...Vertical beam member 21…Beam side closing reinforcement 22a, 23a... Corner 30...Beam member 31…Beam side closing reinforcement 40...Vertical beam joint 41...Strip reinforcing bars 42... Bearing reinforcement steel bars 50…Horizontal beam joint 51...Strip reinforcing bars 52... Bearing reinforcement steel bars L p …Equivalent plastic hinge length M m …Maximum bending moment p w …Strip reinforcement ratio p t …Tensile reinforcement ratio θ pm …Plastic hinge rotation angle φ m …curvature X…Stretching direction Y: Width direction

Claims

1. A method for designing a column-beam joint in a rigid-frame concrete structure having a column-beam joint formed by joining a column member and a beam member using a precast construction method, comprising: The column-beam joint is A structure in which column-side closing reinforcing bars of a closed shape protruding from the surface of the column member at a predetermined interval in a predetermined direction and beam-side closing reinforcing bars of a closed shape protruding from the surface of the beam member at a predetermined interval in the predetermined direction are overlapped in the predetermined direction, band-shaped reinforcing bars are wrapped around the overlapped column-side closing reinforcing bars and beam-side closing reinforcing bars along the predetermined direction, and concrete is poured into lap joints where bearing reinforcement reinforcing bars are arranged along the predetermined direction at corners of the column-side closing reinforcing bars and corners of the beam-side closing reinforcing bars, The plastic hinge rotation angle θ of the column-beam joint is used to calculate the displacement of the column-beam joint that can maintain the maximum bending moment. ｐｍ The ratio of the reinforcement bars in the beam-column joint is p ｗ (%) and tensile reinforcement ratio p ｔ (%) and calculate using the following formula [Equation 1] Design methods for beam-column joints.

2. The curvature φ of the beam-column joint that can maintain the maximum bending moment ｍ The plastic hinge rotation angle θ ｐｍ , and the equivalent plastic hinge length L ｐ Calculate using the following formula: [Equation 2] The method for designing a beam-column joint according to claim 1 .

3. When a predetermined input assuming earthquake motion is applied to the concrete structure, the curvature of the column-beam joint due to bending deformation is the curvature φ of the column-beam joint that can maintain the maximum bending moment. ｍ The beam-column joint is designed so that it is less than The method for designing a beam-column joint according to claim 2.

4. A rigid-frame viaduct having a column-beam joint formed by joining column members and beam members using a precast construction method, The column-beam joint is formed by overlapping, in the predetermined direction, column-side closing reinforcing bars of a closed shape that protrude from the surface of the column member at a predetermined interval in a predetermined direction and beam-side closing reinforcing bars of a closed shape that protrude from the surface of the beam member at a predetermined interval in the predetermined direction, and wrapping band-shaped reinforcing bars around the overlapped column-side closing reinforcing bars and beam-side closing reinforcing bars along the predetermined direction, and pouring concrete into lap joints where bearing reinforcement reinforcing bars are arranged along the predetermined direction at the corners of the column-side closing reinforcing bars and the corners of the beam-side closing reinforcing bars, A beam-column joint designed by the method for designing a beam-column joint according to claim 2 or 3. Ramen viaduct.

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