Method for setting restoring force model of end RC part in hybrid structure beam

Abstract

To provide a method for setting a resilience model of an end RC section of a mixed structure beam.SOLUTION: It is assumed that beam longitudinal ends 4a and 4b of an end RC section 4 are coupled to a steel beam 3. It is assumed that forces reactive to an operation shearing force (external force) of a mixed structure beam 1 are generated in coupled parts 71 and 72. It is assumed that the end RC section 4 bears at least a part of a bending moment generated in the steel beam 3. It is assumed that the vertical deformations of the steel beam 3 and the end RC section 4 match at the coupled part 72 of the steel beam 3 and the tip 4b of the end RC section 4. Only a shearing deformation of an elastic deformation part is taken into account for the vertical deformations of the steel beam 3 and the end RC section 4. A resilience model of the end RC section 4 is set as a trilinear model in which a bending crack moment and a breakdown moment are rigidity change points. Both a case where a tendon is taken into account and a case where it is ignored are examined in evaluation of a rigidity reduction rate of the end RC section 4. A resilience model of the steel beam 3 is set as a bilinear model in which a breakdown moment is a rigidity change point.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for setting a restoring force model of an end RC structure part in a hybrid structure beam.

Background Art

[0002] As a beam installed between reinforced concrete (hereinafter referred to as RC) columns, both ends in the longitudinal direction of a steel beam installed between RC columns are joined to the RC columns through end RC structure parts that embed the ends of the steel beam, and a tension member is embedded and fixed in the concrete part of the end RC structure part in the longitudinal direction of the beam, and a hybrid structure beam in which a tensile force is introduced into this is known (see, for example, Patent Document 1). In such a hybrid structure beam, the tension member is fixed inside the end RC structure part, or fixed inside the RC column, or penetrates the RC column and is fixed outside the RC column.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a hybrid structure beam, a method for setting a restoring force model of the end RC structure part has not been established.

[0005] Therefore, an object of the present invention is to provide a method for setting a restoring force model of an end RC structure part in a hybrid structure beam.

Means for Solving the Problems

[0006] In order to achieve the above object, a method for setting a restoring force model of an end RC structure part in a hybrid structure beam according to the present invention is provided at both ends in the longitudinal direction of a steel beam installed between RC columns, and is joined to the column and embeds the end of the steel beam. An end RC structure part made of RC, and in the longitudinal direction, a tension member embedded in the concrete part of the end RC structure part and guiding a tensile force, and a method for setting a restoring force model of the end RC structure part in a hybrid structure beam in which the steel beam is joined to the column via the end RC structure part, wherein the end RC structure part is assumed that both ends in the longitudinal direction are coupled to the steel beam, and it is assumed that a reaction force against the acting shear force (external force) of the hybrid structure beam occurs at the coupling part between the end of the end RC structure part and the steel beam, and the end RC structure part is assumed to bear a part of the bending moment generated in the steel beam, and it is assumed that the vertical displacement of the steel beam and the vertical displacement of the end RC structure part are compatible at the coupling part between the end on the side away from the column joined in the end RC structure part and the steel beam, and the vertical displacement of the steel beam and the vertical displacement of the end RC structure part consider only the shear deformation of the elastic deformation component, and the restoring force model of the end RC structure part is a trilinear model with the bending crack moment and the bending yield moment as the rigidity change points. In the evaluation of the rigidity reduction rate of the end RC structure part, both the case considering the tension member and the case ignoring the tension member are considered, and the restoring force model of the steel beam has the bending yield moment as the rigidity change point.

[0007] In the present invention, it is assumed that the steel beam in the end RC structure part of the hybrid structure beam is coupled at both ends of the end RC structure part, and when a shear force (external force) acts on the hybrid structure beam, the reaction force generated at each coupling part is regarded as the acting shear force of the end RC structure part and the steel beam, and the vertical displacement of the steel beam and the vertical displacement of the end (tip) of the end RC structure part on the side away from the column are made compatible, so that the restoring force model of the end RC structure part can be set.

[0008] In addition, in the method for setting the restoring force model of the end RC structure part in the hybrid structure beam according to the present invention, the shear deformation ratio with respect to the bending deformation of the end RC structure part is calculated by the following formula (1), the shear deformation ratio with respect to the bending deformation of the steel beam is calculated by the following formula (2), the vertical displacement at the loading point of the entire member combining the end RC structure part and the steel beam is calculated by the following formula (3), the bending moment at the time of bending crack generation in the end RC structure part, the shear force of the end RC structure part, and the shear force of the entire member are calculated by the following formulas (4) and (5), the bending moment at the time of bending yield in the end RC structure part, the shear force of the end RC structure part, and the shear force of the entire member are calculated by the following formulas (6) and (7), the yield point rigidity reduction rate of the end RC structure part is calculated by the following formula (8), the initial rigidity and the second rigidity in the shear force-deformation relationship of the end RC structure part are calculated by the following formula (9), the initial rigidity and the second rigidity in the shear force-deformation relationship of the entire member due to the end RC structure part are calculated by the following formula (10), the bending moment and the shear force at the time of bending yield of the steel beam are calculated by the following formulas (11) and (12), the initial rigidity in the shear force-deformation relationship of the steel beam is calculated by the following formula (13), the first inflection point load (shear force) and the second inflection point load (shear force) of the entire member are calculated by the following formula (14), the initial rigidity and the second rigidity in the Q-δTOTAL relationship of the entire member are calculated by the following formula (15), and the vertical displacement of the loading point corresponding to each inflection point load of the entire member may be calculated by the following formula (16).

[0009]

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[0010] By adopting such a configuration, a restoring force model of the end RC structure part in the hybrid structure beam can be set. [Advantages of the Invention]

[0011] According to the present invention, a restoring force model of the end RC structure part in the hybrid structure beam can be set. [Brief Description of the Drawings]

[0012]

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Mode for Carrying Out the Invention

[0013] Hereinafter, a method for setting the restoring force model of the end RC structure part in the hybrid structural beam according to the embodiment of the present invention will be described based on FIGS. 1-10. The hybrid structural beam 1 according to the present embodiment shown in FIGS. 1-3 is installed between RC columns 2. FIGS. 1-3 show the vicinity of one end in the length direction of the hybrid structural beam 1 (hereinafter referred to as the beam length direction). The hybrid structural beam 1 is provided at both ends in the beam length direction of a steel beam 3 installed between columns 2, and includes an RC end RC structure part 4 that is joined to the column 2 and buries the end of the steel beam 3, and, in the beam length direction, a tension member 5 that is buried in the concrete part 41 of the end RC structure part 4 and into which a tensile force is introduced. The steel beam 3 is joined to the column 2 via the end RC structure part 4. Hereinafter, the portion where the end RC structure portion 4 is provided in the hybrid structure beam 1 may be referred to as the beam end 1a.

[0014] The end RC structure portion 4 embeds only the end 3a in the beam length direction of the steel beam 3. The end RC structure portion 4 has a concrete portion 41, a beam main reinforcement 42, a shear reinforcement 43, and a concentrated reinforcement 44 embedded in the concrete portion 41. The beam main reinforcement 42 extends in the beam length direction. The end of the beam main reinforcement 42 on the column 2 side protrudes from the concrete portion 41 of the end RC structure portion 4 to the column 2 side and is embedded in the concrete portion 21 of the column 2. A fixing plate 421 is provided at the end of the beam main reinforcement 42 on the column 2 side. The shear reinforcement 43 is provided over the entire length of the end RC structure portion 4 in the beam length direction. The concentrated reinforcement 44 is provided in the vicinity of the end 4b on the side opposite to the end 4a joined to the column 2 in the end RC structure portion 4 (hereinafter, may be referred to as the tip end portion 4b). The end RC structure portion 4 is provided continuously with an RC slab 6 provided on the steel beam 3. The end RC structure portion 4 may be a precast concrete member or may be constructed by a conventional RC construction method.

[0015] The prestressing tendon 5 is a PC steel material such as a PC steel bar or a PC steel wire. The prestressing tendon 5 is provided in the end RC structure portion 4 in a direction extending in the beam length direction. As shown in FIG. 1, the end 5a of the prestressing tendon 5 on the column 2 side may protrude from the concrete portion 41 of the end RC structure portion 4 and further penetrate the column 2, or may be arranged inside the end RC structure portion 4 as shown in FIG. 2, or may protrude from the concrete portion 41 of the end RC structure portion 4 and be arranged inside the column 2 as shown in FIG. 3. The end 5b of the prestressing tendon 5 on the side away from the column 2 protrudes from the end RC structure portion 4.

[0016] A method for setting the restoring force model of the end RC structure portion in the hybrid structure beam according to this embodiment will be described. In the method for setting the restoring force model of the end RC structure portion in the hybrid structure beam, the restoring force model of the end RC structure portion 4 of the hybrid structure beam 1 is set. When setting the restoring force model of the end RC structure part 4, the equivalent rigidity of the composite structure beam 1 is obtained in consideration of the deformation states of the respective constituent members (steel frame beam 3, end RC structure part 4) with different bending rigidities and shear rigidities. After obtaining the equivalent rigidity, a comparison is made with the experimental results of the bending yield of the end RC structure part 4 to confirm the validity of the method for setting the restoring force model according to this embodiment. Hereinafter, the tendon 5 is denoted as PC steel material. The end RC structure part and the steel frame beam are collectively referred to as the entire member.

[0017] As shown in FIG. 4, it is assumed that the end RC structure part 4 has the steel frame beam 3 connected only to both ends in the beam length direction, that is, the end part 4a on the column 2 side and the tip part 4b on the side away from the column 2. The portions where the end parts 4a, 4b of the end RC structure part 4 and the steel frame beam 3 are connected are denoted as connection parts 71, 72. It is assumed that a reaction force against the acting shear force (external force) of the composite structure beam 1 acts on the connection parts 71, 72. Further, when fixing bars or the like are installed at the ends of the steel frame beam 3, a bending moment is generated in this part, so the burden thereof ( s M o ) is also considered.

[0018] When modeling the steel frame beam 3 and the end RC structure part 4, the following assumptions are made. (1) The vertical displacement of the steel frame beam 3 and the vertical displacement of the end RC structure part 4 are compatible at the connection part 72 where the tip part 4b of the end RC structure part 4 and the steel frame beam 3 are connected. (2) The vertical displacement of the steel frame beam 3 and the vertical displacement of the end RC structure part 4 consider the shear deformation of the elastic deformation component. (3) The restoring force model (skeleton) of the end RC structure part 4 is a trilinear model with the bending crack moment and the bending yield moment (considering PC steel material) as the rigidity change points. (4) When evaluating the internal rigidity reduction rate of the end RC structure part 4, two cases of considering / ignoring the PC steel material are examined. (5) The restoring force model (skeleton) of the steel frame beam 3 is a bilinear model with the bending yield moment as the rigidity change point.

[0019] The deformed states of the steel frame beam 3 and the end RC structure part 4 are shown in Fig. 5. The shear deformation ratio with respect to the bending deformation of the end RC structure part is calculated by the following formula (1), the shear deformation ratio with respect to the bending deformation of the steel frame beam is calculated by the following formula (2), and the vertical displacement at the load point of the entire member combining the end RC structure part and the steel frame beam is calculated by the following formula (3).

[0020]

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[0021] Among the joints 71 and 72, at the joint 72 where the tip 4b of the end RC structure part 4 and the steel frame beam 3 are joined, the vertical displacement of the entire member can be obtained by matching the vertical displacement of the tip 4b of the end RC structure part 4 and the vertical displacement of the steel frame beam 3. Fig. 6 shows a method for setting the restoring force model of the entire member from the restoring force models of the steel frame beam 3 and the end RC structure part 4 respectively. Here,

[0022]

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[0023] Verification of restoring force model The evaluation results of the restoring force model of this embodiment were compared with the experimental results of the flexural yielding failure of the end RC structure part, and the validity of the restoring force model according to this embodiment was confirmed. Table 1 shows the list of member performances of the two test specimens (Test Specimen No. 1, No. 3: test specimens with different widths of the end RC structure part) used in the experiment. The physical property values required for setting the restoring force model are obtained based on the information of these test specimens.

[0024] [Table 1]

[0025] Here, in order to examine the influence of the PC steel material on the yield point stiffness reduction rate α of the end RC structure part 4 y calculations were attempted for two cases: when the PC steel material was considered and when the PC steel material was ignored. The evaluation results of the restoring force model are shown in Table 2 (considering PC steel material) and Table 3 (ignoring PC steel material). The comparison with the load-deformation angle relationship obtained from the experiment is shown in Figs. 7-9 (ignoring PC steel material). In Tables 2 and 3, the end RC structure part 4 is denoted as the "RC member", and the ends 4a and 4b of the end RC structure part 4 are denoted as the "RC end" and the "RC tip end", respectively. From this, it can be seen that the method for setting the restoring force model of the end RC structure part 4 of the hybrid structure beam 1 according to the present embodiment is reasonable.

[0026]

Table 2

[0027]

Table 3

[0028] Next, the operation and effect of the method for setting the restoring force model of the end RC structure part in the hybrid structure beam according to the above-described present embodiment will be described. In the method for setting the restoring force model of the end RC structure part in the hybrid structure beam according to the above-described present embodiment, among the joints 71 and 72, in the joint 72 where the tip 4b of the end RC structure part 4 is joined to the steel frame beam 3, by matching the vertical displacement of the tip 4b of the end RC structure part 4 with the vertical displacement of the steel frame beam 3, the vertical displacement of the hybrid structure beam 1 can be obtained, and the restoring force model of the end RC structure part 4 can be set. Since the restoring force model of the end RC structure part 4 of the hybrid structure beam 1 can be set, its validity can be shown with reference to the past experimental results.

[0029] As described above, the embodiment of the method for setting the restoring force model of the end RC structure part in the hybrid structure beam according to the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist thereof. For example, in the above-described embodiment, the PC steel material is provided as the tension member 5 in the hybrid structure beam 1, but a tension member 5 other than the PC steel material may be provided.

Explanation of Reference Numerals

[0030] 1 Hybrid structure beam 2 Column 3 Steel frame beam 3a End 4 End RC structure part 4a End 4b End (tip) 5 Tension member 71, 72 Joint 41 Concrete part

Claims

1. An RC end RC structure provided at both ends in the longitudinal direction of a steel beam erected between RC columns, joined to the columns and embedding the ends of the steel beam, and a tendon embedded in the concrete part of the end RC structure in the longitudinal direction and guiding a tensile force, are provided, A method for setting a restoring force model of an end RC structure in a hybrid structure beam in which the steel beam is joined to the column via the end RC structure, comprising: assuming that both ends in the longitudinal direction of the end RC structure are joined to the steel beam; assuming that a reaction force against the acting shear force (external force) of the hybrid structure beam is generated at the joint between the end of the end RC structure and the steel beam; assuming that the end RC structure bears a part of the bending moment generated in the steel beam; assuming that the vertical displacement of the steel beam and the vertical displacement of the end RC structure are compatible at the joint between the end on the side away from the column to which the end RC structure is joined and the steel beam in the end RC structure; the vertical displacement of the steel beam and the vertical displacement of the end RC structure consider only the shear deformation of the elastic deformation component; the restoring force model of the end RC structure is a trilinear model with the bending crack moment and the bending yield moment as the rigidity change points; in the evaluation of the rigidity reduction rate of the end RC structure, both the case considering the tendon and the case ignoring the tendon are examined; A method for setting a restoring force model of an end RC structure in a hybrid structure beam in which the restoring force model of the steel beam is a bilinear model with the bending yield moment as the rigidity change point.

2. The shear deformation ratio with respect to the bending deformation of the end RC structure is calculated by the following formula (1), The shear deformation ratio with respect to the bending deformation of the steel beam is calculated by the following formula (2), The vertical displacement at the load point of the entire member combining the end RC structure and the steel beam is calculated by the following formula (3), The bending moment at the time of bending crack generation in the end RC structure, the shear force of the end RC structure, and the shear force of the entire member are calculated by the following formulas (4) and (5), The bending moment at the time of bending yield in the end RC structure, the shear force of the end RC structure, and the shear force of the entire member are calculated by the following formulas (6) and (7), The yield point rigidity reduction rate of the end RC structure is calculated by the following formula (8). The initial stiffness and the second stiffness in the shear force - deformation relationship of the end RC structure part are calculated by the following formula (9), The initial stiffness and the second stiffness in the shear force - deformation relationship of the entire member by the end RC structure part are calculated by the following formula (10), The bending moment and the shear force at the bending yield of the steel beam are calculated by the following formulas (11) and (12), The initial stiffness in the shear force - deformation relationship of the steel beam is calculated by the following formula (13), The first inflection point load (shear force) and the second inflection point load (shear force) of the entire member are calculated by the following formula (14), The initial stiffness and the second stiffness in the Q - δTOTAL relationship of the entire member are calculated by the following formula (15), The method for setting the restoring force model of the end RC structure part in the hybrid structure beam according to claim 1, wherein the vertical displacement of the loading point corresponding to each inflection point load of the entire member is calculated by the following formula (16). 【Number 1】 【Number 2】 [Number 3] 【Number 4】 【Number 5】 【Number 6】 【Number 7】 【Number 8】 【Number 9】 【Number 10】 【Number 11】 【Number 12】 【Number 13】 【Number 14】 【Number 15】 【Number 16】

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