JP6352602B2 - Steel - Google Patents

Description

  The present invention relates to a steel material formed by assembling a plurality of members.

  Conventionally, various structures capable of absorbing emergency load energy during an earthquake or storm have been researched and developed. In the case of RC (Reinforced Concrete) or PC (Precast) frames that have energy absorption capacity, the high-strength bending tensile steel that deforms within the elastic range against the emergency load and does not yield, and the energy of the emergency load are heated. Each of the dampers that convert to absorb and absorb was provided as separate members. However, in the configuration in which the damper and the bent tensile steel material are separately provided as in the conventional RC or PC frame, the damper is disposed outside the structural housing and a wall for hiding the damper is necessary, or the human flow line Design constraints such as getting in the way will occur.

Therefore, in addition to forming prestressed steel for prestressed concrete members, tensile force is introduced so that the strain at the time of yielding is exceeded or the stress level is close to the yield point stress level. There is a conventional example of forming a steel material. However, since this conventional example requires two types of steel materials, the increase in the number of on-site construction points reduces the work efficiency and makes it difficult to ensure the stability of construction quality.
In addition, by tempering only the surface of the hardened steel bar, there is a conventional example of a steel material in which a low-strength portion is formed from the surface to a predetermined depth, and the inside of the low-strength portion is a high-strength portion. In addition, it is difficult to uniformly manage the strength of each of the low-strength portion and the high-strength portion, the difference between these strengths, the depth of the low-strength portion, and the like, and ensuring the stability of the construction quality becomes a problem.

In view of the above, in order to provide a bent tensile steel material that can absorb load energy such as earthquakes, does not increase the number of construction points on site, and ensures the stability of construction quality, Are respectively fixed to the structural frame, steel bars inserted into the steel pipe, both ends of which are fixed to the ends of the steel pipe, and steel bars are provided at both ends of the steel pipe to fix the steel bars to the steel pipe, and the steel pipe is compressed. And a fixing member that presses the steel bar from the outside in the axial direction toward the inside in the axial direction when the steel pipe is pressed.The steel pipe has a strength higher than that of the steel bar, and the steel bar has a lower yield point than the yield point of the steel pipe. There is a conventional example of a steel material (Patent Document 1).
In the conventional example of Patent Document 1, both the yield point and the energy consumption amount can be largely secured,
Compared to the case where the strength of the steel bar is higher than the strength of the steel pipe, the steel pipe is restrained without yielding when the compressive force is applied, because the steel pipe instead of the steel bar is made of high strength steel. A large elastic range can be secured. As a result, both the yield point and the energy consumption can be secured larger, so that the load energy in an emergency such as an earthquake or a storm can be sufficiently absorbed. In addition, since the steel pipe and the steel bar are assembled in advance to form a steel material, there is an advantage that the number of construction points in the field does not increase and it is easy to ensure the stability of construction quality.

Japanese Patent No. 5017724

In general, a material having a low yield point that can expect energy consumption performance, that is, a damper effect, is expensive.
In the conventional example of Patent Document 1, the steel bar for obtaining the damper effect is set to a region having a lower yield point than the yield point of the steel pipe in the entire range.
That is, in the conventional example of Patent Document 1, since one steel bar is in the same low yield point region, the manufacturing cost of the steel material is high.

  An object of the present invention is to provide a steel material that can absorb load energy such as earthquakes, does not increase the number of construction points on site, is easy to ensure the stability of construction quality, and has a low manufacturing cost. To do.

Steel of the present invention, a steel tube portion of the axial end side is fixed to the respective structural frame, is inserted into the steel pipe, a steel bar male thread portion Ru are formed on both ends, the male screw portion of the both end portions of the steel pipe in addition to fixing the steel bar has a nut screwed to the steel pipe, respectively, and a fixing member for pressing toward axially inward from the axial outer side of the bars when the steel pipe is compressed, the The steel bar has a low yield point region lower than the yield point or 0.2% yield strength of the steel pipe and the same as the yield point or 0.2% yield strength of the steel pipe or higher than the yield point or 0.2% yield strength of the steel pipe. Yield point regions are arranged side by side in the axial direction, and the male thread portion is arranged in each of the high yield point region and the low yield point region .

In the invention of this configuration, when the tensile force acts on the steel pipe due to the energy of the load acting on the structural housing or the compressive force acts, the steel bar and the steel pipe are integrated by the fixing member. A load exceeding the yield point in the low yield point region is applied. Even after the low yield point region of the steel bar yields, the high yield point region of the steel bar and the steel pipe are deformed within the elastic range. A large yield point can be obtained.
In addition, in the low yield point region of the bar steel after yielding, only the strain increases in a state where the steel tube is restrained without increasing the stress due to the load, so that a large hysteresis due to the loading and unloading of the load can be secured. Since the load energy corresponding to the hysteresis property of the steel bar is consumed, the energy consumption can be increased.
As described above, in the present invention, the steel pipe has higher strength than the steel bar, and the low yield point region of the steel bar is set to the high yield point region and the lower yield point than the steel pipe, as described above, the entire steel material as described above. As a result, energy consumption can be increased.

In addition, by fixing the ends of the steel pipe and the steel bar with an appropriate fixing means, it becomes possible to integrate these steel pipes and the steel bar before on-site construction, so the number of construction sites on the site does not increase. . Moreover, since it is only necessary to manage the strength of each of the steel pipe and the steel bar, it is easier to guarantee the quality of the parts than when the high strength portion and the low yield point portion are formed in one member. In these respects, it becomes easy to ensure the stability of the construction quality.
Moreover, in the present invention, only a part of the low yield point region of the steel bar is formed, so that the manufacturing cost can be reduced as compared with the case where all of the steel bar is used as the low yield point region.

Here, in the steel material relevant to this invention, the said high yield point area | region is each provided in the both ends of the said steel bar, and the said low yield point area | region is preferably provided in the center part of the said steel bar.
In this configuration, since both ends of the steel bar are in the high yield point region, it can be easily integrated with the steel pipe using the fixing member.

  In the present invention, load energy such as an earthquake can be absorbed, the number of construction points on site is not increased, the stability of construction quality can be easily ensured, and the manufacturing cost can be reduced.

The partially broken side view of the steel materials which concern on one Embodiment of this invention. The side view of the principal part of the said steel materials. The side view of the steel pipe which comprises the said steel materials. The side view of the steel bar which comprises the said steel materials. (A) (B) is a side view of the steel bar different from FIG. Schematic which shows the state in which external force PA was applied to the steel bar of the embodiment. (A) is a graph showing the relationship between the load and elongation of the steel bar of this embodiment in which the low yield point region A and the high yield point region B are arranged, and (B) is the load in the low yield point region part. The graph which shows the relationship with elongation, (C) is a graph which shows the relationship between the load and elongation of a high yield point area | region part. (A) is a graph showing the relationship between the load and strain of the steel bar of this embodiment in which the low yield point region A and the high yield point region B are arranged, and (B) is the load in the low yield point region part. The graph which shows the relationship with a distortion, (C) is a graph which shows the relationship between the load and distortion of a high yield point area | region part. Schematic which shows the state in which external force PA was applied to the steel bar of a prior art example. The graph which shows the relationship between the load and elongation of the steel bar of a prior art example, and respond | corresponds to FIG. The graph which shows the relationship between the load and distortion of the steel bar of a prior art example, and respond | corresponds to FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a partially broken side view showing a steel material in the present embodiment. This steel material includes a bending tensile steel material body 10, a mounting nut 20 for fixing a portion of one end side in the axial direction of the bending tensile steel material body 10 to the mounting plate 9 of the structural housing, and an axial end portion of the bending tensile steel material body 10. A first cap nut 30 as a fixing member to be provided, and a second fixing member provided at the other axial end of the bending tensile steel member 10 to fix the bending tensile steel member 10 to the mounting plate 9 of the structural housing. A cap nut 40 is provided.
A washer 21 is interposed between the mounting nut 20 and the mounting plate 9, and a washer 41 is interposed between the second cap nut 40 and the mounting plate 9.

FIG. 2 is a side view of the bent tensile steel member 10. The bending tensile steel member 10 includes a steel pipe 11 (FIG. 3), a steel bar 12 (FIG. 4) inserted into the steel pipe 11, and a round nut 13 (FIG. 4) as a steel bar fixing nut for fixing the steel pipe 11 and the steel bar 12. 2).
The steel pipe 11 is formed of a high-strength steel material, and a steel pipe male threaded portion 111 is formed in each part including from the edge of both ends of the steel pipe 11 to the position fixed to the mounting plate 9 as shown in FIGS. Has been.

Here, the steel pipe 11, than the strength of the steel bar 12 is a high strength, the strength of the steel pipe 11, yield point or 0.2% proof stress exceeds 390 N / mm ² or, or a tensile strength of 490 N / mm ² It is set to exceed. In the present embodiment, "high strength", yield point or 0.2% proof stress exceeds 390 N / mm ² or, or tensile strength refers to exceed 490 N / mm ^2.
In this embodiment, a material having a yield point and a 0.2% yield strength defined in the reinforced concrete structure design standard of the Architectural Institute of Japan is used. That is, the steel material whose yield point or 0.2% proof stress corresponds to 390 N / mm ² is, for example, a deformed reinforcing bar SD390 for reinforced concrete construction. In the Architectural Institute design standards for reinforced concrete, the allowable stress level is determined up to SD390. A steel material having a tensile strength of 490 N / mm ² is, for example, a steel material SN490 (SM490) for steel frame construction. In the steel building design standards written by the Architectural Institute, the allowable stress level is determined up to this SN490 (SM490).
From the above, when the yield point or 0.2% proof stress exceeds 390 N / mm ² , the high yield point region is high strength, or when the tensile strength exceeds 490 N / mm ² , the high yield point region is high strength. In this case, the yield point as a whole steel material can be made higher.

As shown in FIGS. 2 and 4, the steel bar 12 is formed with a steel bar male thread part 121 protruding from the end of the steel pipe 11.
As shown in FIG. 4, in the steel bar 12, a low yield point region A that is a lower yield point than the yield point of the steel pipe 11 and a high yield point region B that is the same as the yield point of the steel pipe 11 are arranged side by side in the axial direction. Yes. These low yield point region A and high yield point region B have the same cross-sectional area.
The low yield point region A has a yield point or 0.2% yield strength that is less than the yield point or 0.2% yield strength of the high yield point region B.
Low yield point region A is a length L _A from one end of the bars 12, the high yield point region B has a length from the other end of the steel bar 12 is L _B. L _A + L _B is the entire length L of the steel bar 12.

In the present embodiment, the arrangement of the low yield point region A and the high yield point region B in the steel bar 12 is not limited to the structure shown in FIG.
For example, as shown in FIG. 5 (A), the high yield point region B may be provided at both ends of the steel bar 12, and the low yield point region A may be provided at the center of the steel bar 12.
One of the high yield point region B of the high yield point region B of the two positions, the length from one end of the steel bar 12 is L _B1, the other high-yield area B, the length from the other end of the steel bar 12 Is L _B2 . The total length L _B of the high yield point region B is L _B1 + L _B2 , and when the total length L _B and the length L _A of the low yield point region A are summed, the total length of the steel bar 12 L. The length L _B1 and the length L _{B2 of the} high yield point region B may be the same or different.
Further, as shown in FIG. 5B, the low yield point region A may be provided at both ends of the steel bar 12, and the high yield point region B may be provided at the central part of the steel bar 12.
The length from one end of one low yield point region A of the two low yield point regions A is L _A1 , and the length from the other end of the other low yield point region A is L _A2 . The total length L _A of the low yield point region A is L _A1 + L _A2 , and the total length L _A and the length L _B of the high yield point region B have the same relationship as in the example of FIG.

Here, the ratio of the length L _B of the length L _A of the low yield point region A high yield point region B is determined by the magnitude of the plastic deformation capacity of the low yield point region A. That is, as the uniform elongation of the low yield point region A increases, the required length of the low yield point region A decreases. In the present embodiment, a steel material in a low yield point region A that can ensure uniform elongation of 40% to 50% (60% to 80% in terms of elongation at break) is prepared.
Further, the energy consumption capacity is greatly influenced by the difference between the yield point or the 0.2% yield strength in the low yield point region A and the yield point or the 0.2% yield strength in the high yield point region B. That is, the lower the yield point or 0.2% yield strength of the low yield point region A, or the higher the yield point or 0.2% yield strength of the high yield point region B, the greater the energy consumption capability. Here, the ratio of the yield point or 0.2% yield strength of the low yield point region A to the yield point or 0.2% yield strength of the high yield point region B is the ratio of the yield with respect to the low yield point region A. The ratio is from 1: 2 to 1:16, preferably from 1: 3 to 1:15, more preferably 1:13. For example, when the yield ratio based on the low yield point region A is from 1: 3 to 1:15, the yield point of the low yield point region A or the 0.2% proof stress is about 100 N / mm ² and steel 240 N / mm ² about things, yield point or 0.2% proof stress of the high yield point region B consists of a combination of a steel ones from of about 785N / mm ² of about 1300 N / mm ^2. When the yield ratio is 1:13, the yield point in the low yield point region A or 0.2% proof stress is about 100 N / mm ² and the yield point in the high yield point region B or 0.2% proof strength is 1300 N. / mm ² about a combination of steel.
The ratio of the low yield point region A to the total length of the steel bar varies depending on the yield ratio of the high yield point region B with respect to the low yield point region A and other conditions, but is generally 1/10 or more and 1/2 or less. It is.

It will be described based on FIGS. 6 to 11 that the steel bar 12 in which the low yield point region A and the high yield point region B coexist as in the present embodiment is more effective than the conventional steel bar.
The present embodiment will be described with reference to FIGS.
FIG. 6 shows a model of the steel bar 12 of this embodiment. The steel bar 12 is a PC steel bar having a Young's modulus E of 2.06 × 10 ⁵ N / mm ² .
In FIG. 6, L _A is a tensile pre length of the low yield point area A, L _B is the tensile previous length of the high yield point region B. Here, the cross-sectional shapes of the low yield point region A and the high yield point region B are the same circle.

6, adding an external force P _A in the axial direction of the steel bar 12, the length extending of the low yield point region A is [Delta] L _A, since the extended length of the high yield point region B is [Delta] L _B, The total length of the steel bar 12 is ΔL (= ΔL _A + ΔL _B ). Therefore, when the external force P _A is applied, the low yield point region _A changes from the length L _A to L _{A ′} (= L _A + ΔL _A ), and the high yield point region B increases from the lengths L _B to L _{B ′} ( = L _B + ΔL _B ), and the entire length of the steel bar 12 is changed from L to L ′ (= L + ΔL).
The overall strain of the steel bar 12 is ε (= ΔL / L), the strain in the low yield point region A is ε _A (= ΔL _A / L _A ), and the strain in the high yield point region B is ε _B (= ΔL _B / L _B ).

FIG. 7A shows a graph showing the relationship between the load and elongation of the steel bar 12 of this embodiment in which the low yield point region A and the high yield point region B are arranged, and FIG. Is a graph showing the relationship between the load and elongation in the low yield point region A, and FIG. 7C shows a graph showing the relationship between the load and elongation in the high yield point region B.
As shown in FIG. 7 (B), the low yield point area A, the external force _{P A} is next _{P Ay} at position [Delta] L _Ay showing the elastic limit, the external force _{P A} is past the position [Delta] L _Ay showing the elastic limit, the load Plastic deformation is performed up to the position of ΔL _{AP with} P _{Ay maintained} . Plastic deformation is _{D (= ΔL AP -ΔL Ay)} .

As shown in FIG. 7C, in the high yield point region B, the elastic deformation is caused to the position where the load _PAy is obtained, and the elongation at this time is ΔL _By .
In the present embodiment, since the low yield point region A and the high yield point region B are arranged side by side with the steel bar 12, the relationship between the load and the elongation is shown in FIG. 7 (B) and FIG. 7 (C). Together. That is, as shown in FIG. 7A, in the steel bar 12 having the low yield point region and the high yield point region, the position ΔL _y indicating the elastic limit is the position ΔL _Ay indicating the elastic limit in FIG. and a 7 position [Delta] L _{by a} value obtained by summing the showing the elastic limit of the _{(C) (ΔL y = ΔL} Ay + ΔL by), above this position [Delta] L _y, while the values of the load _{P Ay} ΔL _P (= plastic deformation to the position of the ΔL _AP + ΔL _By).

FIG. 8 (A) shows a graph showing the relationship between the load and strain of the steel bar 12 of this embodiment in which the low yield point region A and the high yield point region B are arranged, and FIG. 8 (B). Is a graph showing the relationship between the load and strain in the low yield point region A, and FIG. 8C shows a graph showing the relationship between the load and strain in the high yield point region B.
Figure 8 as shown (B), the in low yield point area A, the external force _{P A} is next _{P Ay} at elastic limit strain at that time is _{ε Ay (ε Ay = ΔL Ay} / L). In addition, growth is distortion at the time of the ΔL _AP becomes _{ε AP (ε AP = ΔL AP} / L A). As shown in FIG. 8C, in the high yield point region B, the strain when the external force at the elastic limit becomes P _Ay is ε _B (when ε _Ay ) (ε _B (when ε _Ay ) = ΔL. _B (at ΔLAy) / L _B ).
In this embodiment, since the low yield point region A and the high yield point region B are arranged side by side with the steel bar 12, the relationship between the load and strain is as shown in FIG.
As shown in FIG. 8 (A), the elastic limit when the external force _{P A} distortion is epsilon _y becomes to be a _{P Ay} low yield point region _{A (ε y = ΔL y /} L), and distortion of the total epsilon _P (Ε _P = ΔL _P / L)

In contrast, a conventional steel bar disclosed in Patent Document 1 will be described with reference to FIGS.
FIG. 9 shows a conventional steel bar model. The steel bar is a PC steel bar having a Young's modulus E of 2.06 × 10 ⁵ N / mm ² .
In FIG. 9, L _A is the length before tension of the low yield point region A, which is the total length of the steel bar before tension.
9, adding an external force P _A in the axial direction of the steel bars, the length extending of the bars becomes [Delta] L _A. When the external force P _A is applied, the steel bar changes from the length L _A to L _{A ′} (= L _A + ΔL _A ).
The overall strain of the steel bar is ε (= ΔL / L).

FIG. 10 is a graph corresponding to FIG. FIG. 10A shows a graph showing the relationship between the load and elongation of a conventional steel bar, and FIG. 10B shows a graph showing the relationship between the load and elongation in the low yield point region. FIG. 10C shows a graph showing the relationship between load and elongation in the high yield point region. Since the conventional example is a steel bar having only a low yield point region, FIG. 10A and FIG. 10C are the same, and the high yield point region shown in FIG. Therefore, a substantial graph (line) is not shown in FIG.
As shown in FIG. 10 (A) (B), in the conventional example of steel bar, exceeds the position [Delta] L _y showing the elastic limit, undergo plastic deformation to a position of the left [Delta] L _P values of the load P _Ay. The amount of plastic deformation is D.

FIG. 11 is a graph corresponding to FIG. FIG. 11A shows a graph showing the relationship between the load and strain of the conventional steel bar, and FIG. 11B shows a graph showing the relationship between the load and strain in the low yield point region. FIG. 11C shows a graph showing the relationship between the load and strain in the high yield point region. Since the conventional example is a steel bar having only a low yield point region, FIG. 11A and FIG. 11B are the same, and the high yield point region shown in FIG. 11C, no substantial graph (line) is shown.
As shown in FIGS. 11A and 11B, in the conventional steel bar composed only of the low yield point region, the strain at the elastic limit is ε _Ay , and the entire strain when the strain in the low yield point region is ε _AP. Becomes ε _P (= ε _Ay ).

As shown in FIG. 8 (A), in the steel bar 12 of this embodiment having both the low yield point region A and the high yield point region B, the conventional steel bar consisting only of the low yield point region shown in FIG. 10 (A). Similar to the steel bar of the example, the load _PAy is maintained at an integral value from the elastic limit of the low yield point region, and plastic deformation continues. Further, as shown in FIG. 8 (A), in the steel bar 12 of the present embodiment, the strain becomes constant from the elastic limit in the low yield point region, similarly to the conventional steel bar shown in FIG. 11 (A). .
That is, bars 12 of this embodiment is the same deformation amount ΔL and steel bars of the prior art, since the external force P _A is the load P _Ay, energy consumption is the same. This indicates that even if there is a high yield point region in a part of the steel bar, there is no significant difference in effect compared to the case where all of the steel rods have a low yield point region.
In order to manufacture the steel bar 12 shown in FIG. 4, a steel material consisting of the low yield point region A and a steel material consisting of the high yield point region B are joined together by pressure welding, friction welding, welding, adhesive, screwing, or the like. .

In order to assemble the steel material of this embodiment, first, the steel bar 12 is inserted into the steel pipe 11, and the round nut 13 is screwed into each of the steel bar male thread portions 121. At this time, the round nut 13 is tightly screwed in until the seat surface of the round nut 13 and the end face of the steel pipe 11 are in close contact. In this way, the steel pipe 11 and the steel bar 12 are integrated, whereby the bending tensile steel material body 10 is assembled.
Next, the bending tensile steel member 10 is placed on the mounting plates 9 and 9 of various structural frames such as RC, PC frame, brace frame, etc., and the second cap nut is inserted from one end side of the bending tensile steel member 10 through the washer 41. 40 is screwed into the steel pipe male threaded portion 111. At this time, the bottom face 40A of the second cap nut 40 and the round nut 13 are brought into close contact with each other.
When the bending tensile steel member 10 is fixed to one mounting plate 9 in this way, the mounting nut 20 is screwed into the steel pipe male threaded portion 111 via the washer 21 from the other end side of the bending tensile steel member 10, and a predetermined torque is obtained. Tighten with. When both ends of the bent tensile steel member 10 are fixed to the mounting plates 9 and 9 in this manner, the first cap nut 30 is screwed into the steel pipe male thread portion 111. At this time, the bottom surface 30A of the first cap nut 30 and the round nut 13 are brought into close contact with each other. As described above, the steel material of the present embodiment is assembled as shown in FIG.

In this embodiment, when a tensile force acts on the bending tensile steel material 10 itself by applying an emergency load energy such as during an earthquake or a storm to the mounting plate 9, a steel pipe 11 fixed to the mounting plate 9; A steel bar 12 fixed to the steel pipe 11 with a round nut 13 extends.
On the other hand, when a compressive force is applied to the steel pipe 11, the steel pipe 11 is compressed and deformed within an elastic range, and the compressive force applied to the steel pipe 11 is transmitted to the steel bar 12 via the first cap nut 30 and the round nut 13. Is done. That is, since the first cap nut 30 presses the steel bar 12 from the outside in the axial direction toward the inside in the axial direction, the steel bar 12 is compressed in a state of being restrained in the steel pipe 11 without jumping out or bending from the end of the steel pipe 11. Is done.

According to the above embodiment, the following effects are mainly obtained.
(1) The bending tensile steel body 10 is a hybrid steel material made of a steel bar 12 including a high-strength steel pipe 11 and a low yield point region A in part. As a result, the distortion in the steel pipe 11 and the distortion in the steel bar 12 are synthesized. Both yield point and energy consumption can be secured greatly. In addition, since the steel bar 12 includes the high yield point region B and the steel pipe 11 has a high strength, the steel bar 12 is compressed compared to the case where the strength of the steel bar 12 is higher than that of the steel pipe 11. It is possible to ensure a large elastic range for restraining the steel bar 12 without yielding the high-strength steel material during the force action.
For the above reasons, both the yield point and the energy consumption can be secured larger, so that the load energy in an emergency such as an earthquake or a storm can be sufficiently absorbed.

(2) Since the steel pipe 11 and the bar steel 12 are assembled in advance to form the bent tensile steel body 10, the number of construction points at the site does not increase, and it is easy to ensure the stability of construction quality.
(3) Since only a part of the low yield point region A of the steel bar 12 is formed, the manufacturing cost is lower than that of the conventional example of Patent Document 1 in which all of the steel bar 12 is a low yield point region. it can.

(4) Since the high yield point region B is provided at both ends of the steel bar 12 and the low yield point region A is provided at the central part of the steel bar 12, and is disposed between the low yield point regions A, It is possible to easily integrate the steel pipe 11 with the first cap nut 30 and the second cap nut 40.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the above embodiment, the yield point of the high yield point region B is the same as the yield point of the steel pipe 11, but in the present invention, the yield points of the high yield point region B and the steel pipe 11 may be different.
Furthermore, the cross-sectional areas (thicknesses) of the low yield point region A and the high yield point region B may be different. For example, since it is easy to change the cross-sectional shape of the low yield point region A, the energy consumption capacity can be controlled by changing the thickness.
Further, in the present invention, in order to manufacture the steel bar 12, a rebar rod body having the same yield point as that of the low yield point region A is prepared, and one end side of the rebar rod body is heat-treated to obtain a high yield point. The region B may be formed.

In the said embodiment, although the edge part of the steel pipe 11 and the edge part of the bar steel 12 were being fixed by the round nut 13, the fixing means of the edge part of a steel pipe and the edge part of a bar steel is a fixing means by such a screw. Is not limited.
In the above-described embodiment, on one end side of the bent tensile steel material body 10, a mounting nut 20 for mounting and fixing the bent tensile steel material body 10 to the mounting plate 9 and a first cap nut 30 for suppressing protrusion of the bar steel 12 are provided separately. However, when the length from the edge of the steel pipe 11 to the mounting position on the mounting plate 9 is constant, the mounting nut 20 and the first cap nut 30 may be integrally formed.
In the above embodiment, the second cap nut 40 serves both as a fixing means to the mounting plate 9 and a means for pressing the steel bar 12 so as not to jump out of the steel pipe 11. Instead, the mounting nut 20 and the first cap nut 30 may be provided.
In addition, the means for fixing the bending tensile steel material to the structural housing is not limited to the mounting nut 20 and the second cap nut 40 of the above embodiment, and may be any appropriate means.

  And the steel materials provided with the high-strength steel pipe and low yield point bar steel of the present invention can be applied to RC main bars, PC frames, brace frames and the like. Here, since the brace frame has not been provided with an energy absorption mechanism in the past, it was necessary to design the brace member with a sufficient cross section, but the steel material of the present invention was used as a brace member to provide energy absorption capability. Because the braced frame is realized, the cross section of the brace is not excessive.

  The present invention can be used for building structures using prestressed concrete members and other building structures.

DESCRIPTION OF SYMBOLS 9 ... Mounting plate (structural housing), 10 ... Bending tensile steel body, 11 ... Steel pipe, 12 ... Steel bar, 13 ... Round nut (steel bar fixing nut), 20 ... Mounting nut, 30 ... First cap nut (fixing member), 40 ... 2nd cap nut (fixing member), 111 ... Male thread part (steel pipe male thread part), 121 ... Male thread part (bar steel male thread part), A ... Low yield point area, B ... High yield point area

Claims (1)

Steel pipes each having axially opposite ends fixed to the structural frame,
A steel bar inserted into the steel pipe and formed with male threaded portions at both ends; and
The steel pipe has nuts that are respectively screwed into male screw portions at both ends of the steel pipe, and the steel bar is fixed to the steel pipe, and when the steel pipe is compressed, the steel bar is pressed from the outside in the axial direction toward the inside in the axial direction. A fixing member,
The steel bar has a low yield point region lower than the yield point or 0.2% yield strength of the steel pipe and the same as the yield point or 0.2% yield strength of the steel pipe or higher than the yield point or 0.2% yield strength of the steel pipe. The high yield point region is arranged side by side in the axial direction,
The steel material, wherein the male thread portion is disposed in each of the high yield point region and the low yield point region.

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