JP3965210B1 - Unbonded brace - Google Patents

Abstract

Provided is an unbonded brace that can easily shift to a higher-order mode without depending on the complete restraint of buckling, so that end buckling is unlikely to occur, and that exhibits its performance at low cost and efficiency. .
SOLUTION: A core brace 2 that bears an axial force, a cylindrical stiffener 1 through which the core brace 2 is inserted to control buckling, and a buckling mode of the core brace 2 are easily shifted to higher order. As shown in the figure, the projection 3 provided on the outer surface of the core brace 2 at the peaks and valleys of the waveform of the higher-order mode buckling of the third or higher order, and between the projection 3 and the stiffener 1 An unbonded brace characterized by having a gap. Further, the protrusion 3 may be provided on the inner surface of the stiffener 1. Further, instead of providing the protrusion 3, the core brace 2 itself may be bent into a substantially waveform.
[Selection] Figure 1

Description

  The present invention relates to a structure of an unbonded brace which is a buckling restraining member for vibration suppression used as a structural element that resists horizontal force such as seismic force or wind force in buildings and other structures.

As shown in FIG. 11, conventionally, as an unbonded brace used for a building or other structure, a reinforced concrete or a concrete member for restraining buckling reinforced by a steel pipe is used as a cylindrical stiffener 1 inside. There is known a structure in which a steel axial force member is inserted as a core brace 2 and a surface between the axial force member and a concrete member is not attached. Since the stiffener does not bear the axial force, the weak point of the concrete that is weak against the tensile axial force can be eliminated. In addition, a steel axial force member that is normally weak against buckling is restrained from buckling, and high rigidity and proof stress are obtained against the compression axial force.
For this reason, the rigidity and the proof stress with respect to the compression axial force are almost equal to those with respect to the tensile axial force. Therefore, the hysteresis characteristics in the force-displacement graph (not shown) are spindle-shaped, and the member is excellent in earthquake resistance.

In addition, as a technology that does not cause internal buckling, a technology that constrains buckling by shortening the buckling length when the core brace is supported at the tip of the bolt and divided into parts in the longitudinal direction. (Patent Documents 1 and 2 below). This is intended to reduce the weight of the stiffener because it is easy to manufacture without having to fill the stiffener with a filler. The inventor has published papers in Non-Patent Documents 1 and 2 below.
Patent Publication 11-029987 Unbonded Brace Patent Publication 11-029978 Unbonded Brace "Study on the required stiffness of unbonded braces with reinforced concrete stiffeners", Architectural Institute of Japan, No.521, pp.141-147, July 1999, Kazuto Yoshida, others "Study on shear stress of unbonded brace edge by reinforced concrete stiffener", Architectural Institute of Japan, No.521, pp.149-156, July 1999, Kazuto Yoshida, others

  Theoretically, the unbonded brace bears the compressive axial force (FIG. 12A-1), and when this axial force is increased and the axial force that causes the primary mode buckling is reached, the initial displacement becomes the first. The core brace is bent (FIG. 12A-1), and the central portion is in contact with the stiffener (FIG. 12A-2). As the axial force increases, the contact portion at the center of the core brace begins to expand (FIG. 12 (A-3)). When contact is made to some extent, theoretically, the transition to a shape having a low energy amount, that is, the transition to higher-order mode buckling starts (FIG. 12 (A-4)). In this case, it is a tertiary mode.

  However, since the surface is often smooth with few initial irregularities of the core brace and the stiffener, it is the same behavior until the middle (FIGS. 12 (B-1) to (B-3)), Without obtaining an opportunity to shift to higher order mode, the contact surface only widens, and eventually the core brace buckles near both ends of the stiffener (FIG. 12 (B-4)). When this end buckling occurs, the rigidity and proof strength against the compression axial force decrease.

  The rigidity and proof strength against the compression axial force increase in the order of first-order mode buckling, end buckling, higher-order mode buckling, and complete buckling restraint. The stiffness and yield strength in higher order mode buckling is high and is almost the same as in full restraint of buckling.

In the techniques of Patent Documents 1 and 2, the core brace is supported by a large number of bolts provided on the inner surface of the stiffener.
Thus, it is not necessary to fill the stiffener with a filler, which is easy to manufacture and is aimed at reducing the weight of the stiffener. Because of the large number of bolts and the absence of a gap between the bolt and the core brace, the deflection of the core brace is completely suppressed to prevent internal buckling (full restraint of buckling). It is clear.

  However, if the transition to higher-order mode buckling is not possible, as described above, as in the case where end buckling is likely to occur, a structure for completely restraining buckling as in the techniques of Patent Documents 1 and 2. In this case, end buckling is likely to occur. Moreover, in order to prevent this, it is difficult to make the length of the core brace exposed from the stiffener very short because there is a part attached to the building in the exposed part. For this reason, the core brace hardly deforms with respect to the compression axial force (FIGS. 12C-1 and C-2), and eventually the core brace buckles near both ends of the stiffener (FIG. 12). (C-3)).

  If the end buckling is performed, the required performance of the unbonded brace (equal rigidity during compression and pulling) cannot be obtained, so buckling at the end must be avoided. To that end, measures have been taken so far, such as reinforcement with plates at the ends and an increase in cross section at the ends of the braces. In order to prevent buckling at the edges, these reinforcements need to be carried out to the inside of the stiffener, which necessitates the production of braces and the processing of stiffeners, increasing the manufacturing cost of unbonded braces. End up.

  Therefore, the present invention provides an unbonded brace that can easily shift to a higher-order mode without depending on the complete restraint of buckling, and therefore, end buckling is unlikely to occur, and that exhibits its performance inexpensively and efficiently. The issue is to provide.

In order to solve the above-described problems, the first invention includes a core brace that bears an axial force, a cylindrical stiffener that is inserted through the core brace and controls buckling, and a buckling mode of the core brace. A projection provided on the outer surface of the core brace at the peak and valley portions of the waveform of the higher-order mode buckling of the third order or higher, and the projection and the stiffener An unbonded brace characterized by having a gap between them.
In the second invention, a core brace that bears an axial force, a cylindrical stiffener that is inserted through the core brace to control buckling, and a buckling mode of the core brace is easily shifted to a higher order. Having a protrusion provided on the inner surface of the stiffener at the crest and trough portions of the third or higher order mode buckling waveform, and a gap between the protrusion and the core brace. It is an unbonded brace.
The third invention further includes a core brace that bears an axial force, a cylindrical stiffener that is inserted through the core brace to control buckling, and a buckling mode of the core brace easily shifts to a higher order. As described above, an initial irregularity obtained by bending the core brace itself into a substantially corrugated portion at the peak and trough portions of the higher-order mode buckling waveform of the third order or higher, and a peak and trough portion of the initial irregular waveform, An unbonded brace characterized by providing a gap with a stiffener.
According to the fourth aspect of the present invention, the gap between the plurality of protrusions or the ridges and valleys of the initial irregular waveform and the stiffener is the largest at the center, and gradually decreases toward the end. An unbonded brace characterized by

According to the first invention, the compression axial force is borne (FIG. 1 (D-1)), and when this axial force is increased, the protrusion at the center portion of the core brace contacts (FIG. 1 (D-2)), By this contact, the core brace is pushed in a direction (hereinafter referred to as X direction) perpendicular to the axial direction (hereinafter referred to as Y direction), and this causes the deformation of both sides of the protrusion thereafter (FIG. 1 (D-3)). As a result, a tertiary mode is formed.
By providing protrusions at the peaks and troughs of the higher and higher order mode buckling waveforms, similar contact and deformation events occur one after another by the core brace protrusions, and easily shift to the higher order mode. . Furthermore, by increasing the degree of higher order and increasing the number of protrusions, the buckling length of the core brace can be shortened to the plastic buckling length, and the performance of the unbonded brace is easily demonstrated. be able to.

Similarly, according to the second invention, when the compression axial force is borne and the axial force is increased, the projection of the central portion of the stiffener contacts the core brace, and this contact causes the core brace to move in the axial direction (hereinafter referred to as Y). 3rd order mode is formed by pushing in a direction (hereinafter referred to as X direction) perpendicular to the direction (hereinafter referred to as “direction”) and then causing deformation on both sides of the protrusion.
By providing protrusions at the peaks and valleys of the higher and higher order mode buckling corrugations, similar contact and deformation events occur one after another due to the stiffener protrusions, making it easier to enter higher order modes. To do. Furthermore, by increasing the degree of higher order and increasing the number of protrusions, the buckling length of the core brace can be shortened to the plastic buckling length, and the performance of the unbonded brace is easily demonstrated. be able to.

Similarly, according to the third aspect of the present invention, when the compression axial force is borne and the axial force is increased, the ridge and valley portions of the initial irregular waveform of the core brace come into contact with the stiffener, and this contact causes the core. The brace is pushed in a direction perpendicular to the axial direction (hereinafter referred to as the Y direction) (hereinafter referred to as the X direction), and this is used as a trigger, and then deformation on both sides in contact proceeds to form a tertiary mode. Become.
By providing bends at the peaks and valleys of the higher and higher order mode buckling waveforms, similar contact and deformation events occur one after another due to the bending of the stiffener and easily transition to higher order modes. To do. Furthermore, by increasing the degree of higher order and increasing the number of bends, the buckling length of the core brace can be shortened to the plastic buckling length, and the performance of the unbonded brace is easily demonstrated. be able to.

  According to the fourth invention, the gap between the plurality of protrusions (the first or second invention) or the peak and valley portions of the irregular waveform (the third invention) and the stiffener is the same at the center. Since it becomes the largest and decreases in order as it goes to the end, with the load of the compression axial force, the contact begins with the central protrusion (first or second invention) or the peak and valley portions of the corrugation (third invention). Touch, then the end ones in turn. For this reason, the behavior of transitioning to higher-order mode buckling in order can be performed smoothly.

(First embodiment)
A first embodiment of the present invention is shown in FIGS.
The core brace 2 that bears the axial force is an iron rectangular cross-section bar. The stiffener 1 having a cylindrical shape with a rectangular cross section inserted through the core brace 2 is also made of iron. When the core brace 2 undergoes third-order higher-order mode buckling, the position of the peak and valley portions of the corrugated shape is determined by the overall length of the core brace 2. Protrusions 3 are provided on the outer surface of the core brace 2 at the peaks and valleys of the W-shaped wave, and therefore at a total of three locations. The protrusion 3 is an elongated cylindrical iron bar and is welded along the outer surface of the core brace 2. The contact with the projection 3 can trigger the transition to a higher mode. The stiffener 1 has a larger cross-sectional area inside the cylinder, and thus has a gap between the protrusion 3 and the stiffener 1. Due to this gap, displacement in the X direction is easy, and a transition to a higher-order mode is performed.

  As shown in FIG. 1, in this embodiment, compression axial force is borne at both ends (FIG. 1 (D-1)), and when this axial force is increased, the protrusion 3 at the center portion of the core brace comes into contact (FIG. 1). 1 (D-2)). By this contact, the core brace 2 is pushed in a direction (X direction) perpendicular to the axial direction (Y direction), and this causes the deformation of both sides of the protrusion 3 to proceed thereafter (FIG. 1 (D-3)). The third-order mode buckling of the letter-shaped waveform occurs.

"Effect of the first embodiment by comparison explanation"
Based on FIG. 12 and FIG. 1, a comparison between general theoretical buckling, actual prior art buckling, and special prior art buckling in which the core brace 2 is supported by a number of bolts. Thus, the effect of the first embodiment is shown.

  In theoretical buckling, when the unbonded brace bears the compression axial force (FIG. 12A-1), the core brace 2 has an initial deflection due to manufacturing errors. When this axial force is increased to become an axial force that causes primary mode buckling, the inner core brace 2 is first bent due to the initial displacement (FIG. 12A-1), and the central portion is the stiffener 1 (FIG. 12A-2). As the axial force increases, the contact portion at the center of the core brace 2 begins to expand (FIG. 12 (A-3)) and shifts to the secondary mode (branch). When contact is made to some extent, the transition to a stable shape with a low energy amount, that is, the third-order mode buckling starts theoretically (FIG. 12 (A-4), in this case, the third-order mode).

  The actual buckling according to the prior art usually has the same behavior until the middle because there are few initial irregularities of the core brace and the stiffener 1 and the surface is often smooth (FIG. 12 (B-1)). (B-3)) The contact surface is only widened without an opportunity to shift to the tertiary mode, and eventually end buckling occurs in which the core brace 2 buckles in the vicinity of both ends of the stiffener 1. (FIG. 12 (B-4)).

  The buckling according to a special prior art in which the core brace 2 disclosed in Patent Documents 1 and 2 is supported by a large number of bolts hardly deforms against the compression axial force (FIG. 12 (C-1)). (C-2)) Eventually, the core brace 2 buckles in the vicinity of both ends of the stiffener 1 (FIG. 12 (C-3)).

On the other hand, in this first embodiment, the unbonded brace bears the compression axial force (FIG. 1 (D-1), and the core brace 2 has an initial deflection due to manufacturing error), and this axial force is When increased, the protrusion 3 at the center portion of the core brace comes into contact (FIG. 1 (D-2)). By this contact, the core brace 2 is pushed in a direction (hereinafter referred to as X direction) perpendicular to the axial direction (hereinafter referred to as Y direction). Thus, the tertiary mode shape is formed in advance.
That is, the transition can be triggered by contact with the protrusion 3. Further, since the gap is formed by the protrusion 3, the displacement in the X direction is easy and the transition is possible. When the axial force is further increased, the mode is actually shifted to the energetically stable third-order mode.

In this way, the core brace 2 easily shifts to the third-order mode buckling regardless of the complete restraint of buckling, so that the end buckling is unlikely to occur, and its performance is exhibited at low cost and efficiently. .
If the buckling is performed at the end as in the prior art, the required performance of the unbonded brace (equal rigidity during compression and pulling) cannot be obtained. Therefore, buckling at the end must be avoided. To that end, measures have been taken so far, such as reinforcement at the end by a plate and increase in cross section at the end of the brace. Since these reinforcements need to be performed up to the inside of the stiffener 1 in order to prevent buckling at the ends, it is necessary to manufacture braces and process the stiffener 1, but according to this embodiment, Thus, it is possible to obtain the performance of the unbonded brace without taking these measures or with very little effort.

(Explanation of higher mode)
In the above first embodiment, the buckling mode is the third order, but the higher order mode buckling that can be implemented as the embodiment of the present invention is not limited to the third order. An example will be described with reference to FIG.
That is, E-1 to E-4 in the figure indicate higher-order modes when the force support condition is pin bonding. These FIGS. E-1 to E-4 are the fourth to seventh modes, respectively. The higher-order modes when the force support condition is fixed joining are similarly shown in F-1 to F-4. Here, F-1 to F-4 are the third to sixth modes, respectively. The difference between E and F in the figure is that when the force point is a pin joint, the mode characteristic of the force point is a wave-shaped node, whereas when both ends are fixed, it is a wave peak or valley. It ’s just a difference.

  Moreover, G of the figure shows the mode by the example of patent document 1,2. That is, the relationship between the axial force and deformation when the center of the core brace is constrained by a bolt or the like is schematically shown. When a compressive axial force is loaded in this state (G-1), the displacement of the central portion is constrained, resulting in an S-shape as shown in Fig. G-2. In other words, the mode is secondary. Even if the force is further applied, since the stiffener is smooth, the mode does not branch into higher order, and the contact portion of the brace only expands. (Figure G-3). Eventually, both ends will buckle like G-4.

(Second embodiment)
Comparative experiments according to the second embodiment of the present invention are shown in FIGS.
This experiment is a simulation experiment based on an analysis by a finite element method using a computer, and the second embodiment is for causing fourth-order mode buckling in the experimental model. The stiffener 1 is actually cylindrical, but in order to facilitate the analysis, as shown in FIG. 4C, two plate members for stiffening the core brace 2 were used. In FIG. 4, a comparative example without the conventional projection 3 is shown in FIG. This second embodiment is shown in FIG. 4B, and the protrusions 3 are set so that the core brace 2 forms a quaternary mode shape in advance.

  That is, when quaternary mode buckling occurs, the positions of the peaks and valleys of the corrugated shape of the buckling are determined by the overall length of the core brace 2, so at each of these positions, and therefore at a total of five locations. The protrusion 3 is provided on the outer surface of the core brace 2. The protrusion 3 has a different height P and width D depending on the protrusion 3. The contact with the protrusion 3 can trigger the transition to the fourth mode. The stiffener 1 has a larger cross-sectional area inside the cylinder, and therefore has a gap between the protrusion 3 and the stiffener 1. Due to this gap, displacement in the X direction is easy, and a transition to a higher-order mode is performed. The height P of the protrusion 3 is the highest at the center P1, and decreases in order of P2 and P3 toward the end. Thereby, the clearance gap between these protrusion 3 and the stiffener 1 is the largest in the center, and becomes small in order as it goes to an end.

1. A comparative experiment was performed by analysis using the finite element method.
Analysis with and without the protrusion 3 on the core brace 2 was performed by the finite element method. The analysis model is shown in FIGS.
Two kinds of models were used for analysis. That is, FIG. 4 (A): Model without projection 3 FIG. 4 (B): Model with projection 3 (5 locations)
A member having a DxB cross section in the center of the figure is the core brace 2. In FIG. (B), the shape of each protrusion 3 is symmetrical with respect to the center, and becomes the shape of P1xD1, P2xD2, and P3xD3 in order from the center to the end.

2 “Analysis Overview”
2.1 Analysis program The general analysis code ANSYS8.1 was used in this analysis. The outline of the analysis is as follows.
2.1.1 Material characteristics The material of the core brace 2 is assumed to be SS400, and a bilinear type having the characteristics shown in FIG. The stiffener 1 was set as an elastic body having a rigidity 1000 times that of the core brace 2 so that the buckling of the core brace 2 can be sufficiently restrained.

2.1.2 Analytical model Fig. 4 shows the model shape and Fig. 5B shows the list of specimens. In FIG. 4, (A) of the comparative example and (B) of this embodiment have the same material characteristics and shape, and the difference is the protrusion 3 added to the core brace 2. This protrusion 3 models the nonuniformity of the stiffener 1 and the core brace 2 ((B)). On the other hand, the type (A) is a model in which the surfaces of the stiffener 1 and the core brace 2 are quite smooth although the core brace 2 has initial deflection. The (A) type is created by removing the protrusion 3 from the (B) type.

Specimen analysis model The clearance e is the distance from the maximum protrusion (J3) to the inside of the stiffener 1 for the (B) protrusion model, and (A) the stiffening from the outer end of the core brace for the uniform model. Indicates the distance to the inside of the material. For this reason, the distance e inside the (B) type stiffener is 14 mm larger than that of the (A) type model. These protrusions are arranged on both sides of the core brace 2 with a uniform space (L2) in the axial direction of the material, with 5 points on one side for a total of 10 points. The center (J1) is changed to P × D = 12 mm × 18 mm, the extreme ends (J3) 4 mm × 18 mm, and the middle (J2) are 8 mm × 18 mm.

  The protrusion interval (L2) is 780 mm, and the slenderness ratio (λ) of the protrusion interval is 60. Both the brace with protrusions and the stiffener 1 were made of a two-dimensional solid with an intermediate point having two translational degrees of freedom, and the core brace 2 was divided into five layers with a width B. The boundary condition of the core brace 2 is that the lower end is completely fixed, and the upper end is constrained to rotate at the end. is doing. The initial irregular shape of the core brace was the primary mode of linear buckling analysis in both models (A) and (B), and the amplitude was 1 mm. The loading method to the core brace 2 was monotonic loading, and the final load was 1015kN assuming 4 times the linear buckling load.

3. Analysis results 3.1 Protrusion model
Figures 6 (a) to 6 (f) show the main branches of the modes based on the elasto-plastic analysis results. In the output of the deformation, the distance between the core brace 2 and the stiffener 1 is increased by about 300 times so that the distance is 600 mm. Moreover, the numerical value in the figure has shown the reaction value of the output of an analysis result. The compression axial force was (a) 90 kN (b) 393 kN (c) 522 kN (d) 792 kN (e) 987 kN (f) final in order in the figure.

The transition of deformation is as follows. First, the central portion of the core brace is buckled, causing lateral displacement (FIG. 6 (a)). Thereafter, the lateral displacement progresses as the load increases, and the projection 3 in the central portion comes into contact with the stiffener 1 (FIG. 6B). As the load is increased, the upper end portion once moves to the left side, and after exhibiting a slightly S shape, the upper portion of the S shape returns to the original state (FIG. 6 (c)). Thereafter, the expansion of the contact portion between the core brace 2 and the stiffener 1 begins to spread (FIG. 6 (d)). When the contact surface of the core brace spreads to some extent, both sides in the vicinity of the central protrusion are deformed in the lateral direction from the protrusion and become a “<” shape. That is, the protrusion 3J3 causes the deformation of the core brace 2 to become non-uniform, and mode branching begins to occur (FIG. 6 (e)). Immediately after reaching this mode, the final shape was reached (FIG. 6 (f)).
The gap between the protrusions 3 and the stiffener 1 is the largest at the center and gradually decreases toward the end, so the center protrusion 3 (J3) comes into contact first, and the next protrusion 3 (J2) and 3 (J1) contact in order. The behavior of shifting to higher-order mode buckling in the order of (a), (b), (c), (d), (e), and (f) can be performed smoothly.

3.2 Uniform model Fig. 7 (a) to Fig. 7 (c) show deformation views of the model (A) in which the stiffener 1 and the core brace 2 are smooth and have no non-uniformity. In the output of these modified drawings, the distance between the core brace 2 and the stiffener 1 is enlarged about 43 times so that the distance between the core brace 2 and the stiffener 1 is 600 mm. Since the enlargement ratio is different from the model (B), the vertical deformation amount of the upper end portion of the core brace appears to be greatly different. The compression axial force was (a) 186 kN (b) 251 kN (c) final in the order in the figure.

  As with the protrusion model, as the load increases, the lateral displacement advances due to the initial deflection existing in the center of the core brace 2 (FIG. 7 (a)), and thereafter the central portion contacts the stiffener 1 (FIG. 7). (b)). However, since there is no non-uniformity, the deformation only expands the contact portion between the central portion and the stiffener 1 as the load increases without branching to a higher-order mode that is stable in terms of energy. This trend continued until the final situation (FIG. 7 (c)), and it was found that simply considering contact did not result in an analysis reflecting many experimental results.

4). Summary As a result of contact analysis of the core brace 2 and the stiffener 1 by the finite element method for the purpose of obtaining precise unbonded brace behavior, the following has been found. (1) When there is no non-uniformity between the stiffener 1 and the core brace 2, no mode branching occurs and no wave-like deformation (high-order mode buckling) occurs. (2) By providing the protrusion 3 on the core brace 2 in order to model the non-uniformity, it can be said that mode branching occurs and a higher-order mode is generated to reflect the experimental results.

"Other embodiments"
In the above embodiment, the protrusion 3 is an elongated cylindrical iron rod. However, in other embodiments, a hemispherical shape may be used.
In the above embodiment, the shape of the core brace 2 is a plate having a rectangular cross section. However, in another embodiment, a cylindrical iron rod can be used. In that case, it is desirable that the stiffener 1 is a cylinder or a square cylinder, and the protrusion 4 is a ring-shaped protrusion surrounding the circumference of a columnar iron rod.

  In the above embodiment, the buckling is the third-order mode or the fourth-order mode, but in other embodiments, the mode can be set to the fifth-order mode or more (see FIG. 8). That is, by providing the protrusions 3 at the peaks and valleys of the 5th-order or higher-order mode buckling waveform, the contact and deformation events described above occur one after another, and the mode can be easily shifted to the higher-order mode. it can. That is, by advancing higher modes and increasing the number of protrusions 3, the buckling length of the core brace 2 can be shortened to the plastic buckling length before long, and the performance of the unbonded brace can be easily improved. It can be demonstrated.

  In the above embodiment, the protrusion 3 provided on the outer surface of the core brace 2 is provided. However, in another embodiment, the protrusion 4 is provided on the inner surface of the stiffener 1 as shown in FIG. May be. That is, as shown in the figure, a protrusion 4 is provided on the inner surface of a cylindrical stiffener 1 that is inserted with a core brace 2 that bears an axial force and controls buckling. The protrusions 4 are provided at the peaks and troughs of the waveform of the third and higher order mode buckling so that the buckling mode of the core brace 2 can easily shift to the higher order. Further, there is a gap between the protrusion 3 and the core brace 2.

  Further, as shown in FIG. 10, the core brace 2 itself may be bent into a substantially waveform. That is, in the core brace 2 itself that bears the axial force, an initial irregularity that is bent substantially into a waveform is formed at the peaks and valleys of the third and higher order mode buckling waveforms. There is a gap between the peaks and valleys of the initial irregular waveform and the stiffener 1.

  In the above embodiment, the spacing between the protrusions is the same, but in other embodiments, the spacing near the end is made shorter than the spacing of the general portion, thereby buckling at the end. Can hardly occur.

It is a continuation figure showing the behavior which causes buckling deformation by compression axial force by the longitudinal section showing the unbonded brace concerning a first embodiment of this invention. It is a disassembled perspective view which shows the outline of the unbond brace of FIG. It is a figure explaining the buckling mode of the higher-order mode which can be implemented as embodiment of this invention, and the buckling mode of a prior art example, and (E-1)-(E-4) are support conditions of pin joining. (F-1) to (F-4) are continuous diagrams showing the theoretical behavior when the support conditions are fixed joints, and (G-1) to (G-4). ) Is a continuous diagram illustrating the mode dimensions and behavior of Patent Documents 1 and 2 of the conventional example. The unbonded brace which concerns on 2nd embodiment of this invention is shown with the comparative example of a comparative experiment, (A) is a figure of a comparative example, (B) is a figure of 2nd embodiment, (C) is (A). Alternatively, (B) is an end view, and (D) is a diagram showing dimensions by emphasizing the protrusion (B). (A) is a chart showing the characteristics of the material of the experimental model, and (B) is a chart showing a list of test specimens in the experiment. In the CG photograph which shows the analysis result of experiment, it is a continuous figure which shows a mode that the unbonded brace which concerns on 2nd embodiment raise | generates buckling deformation by compression axial force. It is a CG photograph which shows the analysis result of experiment, and is a continuous figure which shows a mode that the unbond brace which concerns on a comparative example raise | generates buckling deformation by a compression axial force. FIG. 6 is a perspective view showing a core brace according to another embodiment of the present invention for providing more protrusions and causing higher-order mode buckling. It is the disassembled perspective view of what provided the protrusion provided in the inner surface of the stiffener in the unbonded brace which concerns on other embodiment of this invention. The stiffener is halved vertically and one side is indicated by a broken line. FIG. 6 is an exploded perspective view of an unbonded brace according to another embodiment of the present invention in which the core brace itself is bent into a substantially waveform. It is a perspective view of the unbonded brace of a prior art example. It is a chart of the continuous figure which shows the behavior which causes buckling deformation by compression axial force by the longitudinal cross-sectional view which shows the unbonded brace of a prior art example, and (A-1)-(A-4) show theoretical behavior. Continuous view, (B-1) to (B-4) are continuous views showing normal behavior, and (C-1) to (C-4) are continuous views showing behavior of unbonded braces of Patent Documents 1 and 2. .

Explanation of symbols

  1 ... stiffener, 2 ... core brace, 3 ... projection.

Claims (3)

A core brace bearing the axial force, a cylindrical stiffener inserted through the core brace to control buckling, and a third or higher order so that the buckling mode of the core brace easily shifts to a higher order. An unbonded brace having protrusions provided on the outer surface of the core brace at the peak and valley portions of the corrugation of higher mode buckling, and a gap between the protrusion and the stiffener . A core brace bearing the axial force, a cylindrical stiffener inserted through the core brace to control buckling, and a third or higher order so that the buckling mode of the core brace easily shifts to a higher order. An initial irregularity in which the core brace itself is bent into a substantially corrugated portion at the peak and valley portions of the higher-order mode buckling waveform, and between the peak and valley portions of the initial irregular waveform and the stiffener. An unbonded brace characterized by providing a gap. The gap between the plurality of projections or peaks and valleys of the portion of initial imperfection of the waveform and the stiffener are larger central one is best, claim 1, characterized in that smaller sequentially as it goes to the end, or Unbonded brace according to 2 .