JP7683982B2 - Buckling Restrained Brace - Google Patents

Description

The present invention relates to a buckling restraint brace.

Buckling-restrained braces with buckling prevention measures have been used as braces to form building frames (column-beam frames, roof frames, etc.). Buckling-restrained braces come in a variety of stiffening configurations, including a steel core stiffened only with steel plates, a steel core stiffened with RC (Reinforced Concrete), and a steel core covered with steel and mortar.

Patent Document 1 proposes a buckling-restrained brace in which a core member is restrained by restraining members formed of a pair of square steel pipes, and which does not cause localized damage to the restraining members that receive pressure from the core member. Specifically, the buckling-restrained brace includes a core member that has joints at both ends of the plate-shaped portion for joining to other members, and restraining members that are arranged opposite each face that is perpendicular to the weak axis direction of the plate-shaped portion.

In this buckling restraint brace, a steel plate that comes into contact with the restraint material is provided between the plate-shaped portion and the restraint material, and the restraint material, which is made of a square steel tube, has corners with curved areas at the intersections of each of its surface portions. A weld is provided between the surface of the steel plate that comes into contact with the restraint material and the corner of the restraint material to secure the restraint material to the steel plate.

Patent No. 6445862

The buckling restraint brace described in Patent Document 1 makes it easy to use components such as prefabricated square steel pipes as restraint materials, making it possible to suppress localized damage to restraint materials subjected to compressive force from the core material without incurring high costs.

The buckling restrained brace is incorporated into the building frame by bolting its both ends to connecting fixtures such as brackets and gusset plates that are installed at the corners of the building frame. When the building frame is deformed during an earthquake, external forces such as horizontal forces during the earthquake enter the ends of the buckling restrained brace via brackets, etc., and the external forces are transmitted from the ends of the core material to the entire area as compressive forces, etc., causing plastic deformation throughout the entire core material, thereby demonstrating the energy absorption performance during an earthquake. More specifically, when a compressive force acts on the core material, higher-order mode buckling (wavy deformation) occurs throughout the entire area in the weak axis direction, and the entire core material is buckled as evenly as possible, allowing the entire buckling restrained brace to demonstrate its overall plastic deformation performance.

In the buckling restraint brace described in Patent Document 1, in order to cause the above-mentioned higher-order mode buckling, an unbonded material with deformable properties, such as butyl rubber, is interposed between the wide surface of the core material and the restraining material, and the thickness of the unbonded material is used as a clearance, within which higher-order mode buckling occurs when the core material is subjected to a compressive force.

When applying the above-mentioned butyl rubber to unbonded materials, there are generally no commercially available standard butyl rubber products with dimensions that can be directly applied to buckling restraint braces, and the current situation is that when applying to buckling restraint braces, the material must be cut to fit the dimensions, so it is difficult to say that the cross-sectional adaptability to buckling restraint braces is good, and there are issues such as it being difficult to use square steel pipes (restraint materials) of various shapes and dimensions.

The present invention was made in consideration of the above problems, and aims to provide a buckling restraint brace that has a mechanism for preventing localized damage caused by the pressure applied to the restraint material from the core material, and a component that functions as an unbonded material, instead of an unbonded material made of standard butyl rubber.

In order to achieve the above object, one aspect of the buckling restraint brace according to the present invention is as follows:
A steel plate-shaped core material,
A pair of restraining members made of square steel pipes arranged to face the two wide surfaces of the core material;
An insert plate is interposed between the core material and the restraint material,
The strength and hardness of the insert plate are relatively high compared to the core material and the restraining material.

According to this embodiment, by interposing an insert plate between the core material and the restraining material, which has a relatively higher strength and hardness than the core material and the restraining material, the insert plate prevents localized damage caused by the pressing force that the restraining material receives from the core material, and also functions as an unbonded material, that is, prevents friction when the building frame incorporating the buckling restraint brace deforms during an earthquake and the core material and the restraining material slide against each other.

Here, "the strength and hardness of the insert plate are relatively high compared to the core material and the restraining material" means that the relationship between their respective strengths and hardnesses includes the relationship of insert plate > core material = restraining material, insert plate > core material > restraining material, and insert plate > restraining material > core material.

In addition, in order to effectively induce higher-order mode buckling in the weak axis direction of the core material, slits may be provided on the wide surface of the core material. Since providing slits on the wide surface in this manner weakens the strength of the core material in the strong axis direction, spacers may be inserted into the slits on the wide surface as necessary.

Another aspect of the buckling restraint brace according to the present invention is
The core material, the restraint material, and the inner plate are all formed from one of SS material, SN material, and SM material, and the inner plate is formed from a material having relatively high strength and high hardness.

According to this embodiment, the core material, restraint material, and insert plate are all made of SS (Steel Structure) material (rolled steel for general structure), SN (Steel New) material (rolled steel for architectural structure), and SM (Steel Marine) material (rolled steel for welded structure), which are generally available on the market and are as inexpensive as possible. By changing the steel type of the core material, restraint material, and insert plate, it is possible to reduce manufacturing costs while varying their strength and hardness. Here, other materials such as the core material may be any product certified by the Minister of Land, Infrastructure, Transport and Tourism.

Another aspect of the buckling restraint brace according to the present invention is
The core material and the restraining material are formed from any one of SS material, SN material, and SM material, and the inner plate is formed from SC material.

According to this embodiment, the core material and the restraining material are made of one of SS, SN, and SM materials, which are generally available on the market and as inexpensive as possible, and the insert plate is made of SC (Steel Carbon) material (carbon steel for mechanical structures), which is also generally available on the market and as inexpensive as possible. Since SC material generally has higher strength and hardness than SS material and the like, it is possible to reduce manufacturing costs while varying the strength and hardness.

In another aspect of the buckling restrained brace according to the present invention,
The inner plate is characterized in that a gap is provided on the side opposite to the attachment surface to the core material or the restraint material to allow for buckling deformation of the core material.

According to this aspect, an insert plate is attached to at least one of the opposing surfaces of the core material and the restraint material, and a gap (clearance) for buckling deformation is provided between the insert plate and the other member, making it possible to cause higher-order mode buckling of the core material. In this aspect, one side of the insert plate can be connected to either the core material or the restraint material by spot welding, adhesive, etc.

In another aspect of the buckling restrained brace according to the present invention,
A pair of joining plates are fixed to both ends of the core material, and are joined to other members perpendicular to the wide surface,
A reinforcing plate is fixed to the pair of joining plates, and an end of the restraining material is accommodated in a space formed by the wide surface, the pair of joining plates, and the reinforcing plate.

According to this aspect, a pair of connecting plates perpendicular to the wide surface are fixed to both ends of the core material, a reinforcing plate is fixed to the pair of connecting plates, and the end of the restraining material is housed in the space formed by the wide surface and the pair of connecting plates and the reinforcing plate, resulting in a buckling restrained brace with a high-strength end structure. Here, examples of other members to which the connecting plates are joined include connecting jigs such as brackets and gusset plates that protrude into the structural surface from corners of the building frame. Furthermore, if the ends of the core material are webs, the pair of connecting plates perpendicular to this web become a pair of flanges.

Another aspect of the buckling restraint brace according to the present invention is
A pair of stiffening members connects both sides of the pair of restraining members on the sides of the core member,
The core material is surrounded by the pair of restraining materials and the pair of stiffening materials.

According to this embodiment, a pair of stiffening materials connects both sides of a pair of restraining materials on the sides of the core material, so that deformation of the core material in the width direction (strong axis direction) can be restrained by the stiffening materials.

As can be understood from the above explanation, the buckling restraint brace of the present invention can provide a buckling restraint brace that has a mechanism for preventing localized damage caused by the pressure applied to the restraint material from the core material, and a component that functions as an unbonded material, instead of a standard unbonded material made of butyl rubber.

FIG. 1 is an exploded perspective view of an example buckling restrained brace according to embodiments. FIG. 2 is a longitudinal cross-sectional view of a buckling restraint brace according to an embodiment in a pre-assembly state taken in a direction perpendicular to the axis. FIG. 1 is a perspective view of an example of a buckling restrained brace according to embodiments. FIG. 2 is a longitudinal cross-sectional view of the buckling restraint brace according to the embodiment in an assembled state taken in a direction perpendicular to the axis. FIG. 13 is a schematic diagram of a vertical cross section of a buckling restraint brace in a direction perpendicular to the axis, illustrating the state in which a pressing force acts from the core material to the restraint material during higher-order mode buckling. FIG. 13 is a schematic diagram of a vertical cross section in the axial direction of a buckling restraint brace, illustrating the state in which a pressing force acts from the core material to the restraint material during higher-order mode buckling.

The buckling restraint brace according to the embodiment will be described below with reference to the attached drawings. Note that in this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description.

[Buckling Restrained Brace According to the Embodiment]
An example of a buckling restrained brace according to an embodiment and a method for manufacturing the same will be described with reference to Figures 1 to 5. Here, Figure 1 is an exploded perspective view of an example of a buckling restrained brace according to an embodiment, and Figure 2 is a longitudinal cross-sectional view in a direction perpendicular to the axis of the buckling restrained brace according to an embodiment in a pre-assembled state. Also, Figure 3 is a perspective view of an example of a buckling restrained brace according to an embodiment, and Figure 4 is a longitudinal cross-sectional view in a direction perpendicular to the axis of the buckling restrained brace according to an embodiment in an assembled state.

The buckling restraint brace 100 has a core material 10, a pair of restraint members 30 arranged to face the two wide surfaces 10a of the core material 10, and an insert plate 20 interposed between the core material 10 and the restraint members 30. In other words, unlike conventional buckling restraint braces, it does not have a fixed-shaped unbonded material made of butyl rubber.

The core material 10 is formed from an elongated steel plate, and has a narrow width portion 11 at the center of its length where the width of the wide surface 10a is relatively narrow, and a wide width portion 12 at the end of its length where the width of the wide surface 10a is relatively wide.

The core material 10 has a narrow width portion 11 at the center of its length and a wide width portion 12 at the end of its length, so that the narrow width portion 11 at the center can be made into a region that is easily plasticized, and further, the plasticized region can be limited to the narrow width portion 11 at the center.

At the center of the narrow portion 11 of the core material 10, a cylindrical steel protrusion 15 protrudes from the two wide surfaces 10a of the narrow portion 11. The protrusion 15 is joined to the wide surfaces 10a of the narrow portion 11 by welding or the like.

In addition, a long and narrow slit 14 is provided on both sides of the protrusion 15 of the narrow portion 11 of the core material 10, and a steel spacer 17 is inserted into the slit 14 in the X1 direction.

The slits 14 are small holes for adjusting the strength of the core material 10, and the spacers 17 function as internal deformation prevention materials that prevent the core material 10 from deforming inward (deformation in the strong axis direction) due to the provision of the slits 14. The spacers 17 inserted into the slits 14 are restricted in position by a pair of restraining members 30.

The wide sections 12 at both ends of the core material are joined by welding or the like to joining plates 13, which are made of a pair of steel plates and are joined to other members perpendicular to the wide surface 10a.

Bolt holes 12a, 13a are provided in the wide section 12 and the connecting plate 13, respectively, and are aligned with bolt holes of connecting fixtures (other members) such as brackets and gusset plates that protrude into the structural surface from corners of the building frame (not shown), and are bolted together.

A reinforcing plate 18 made of a steel plate is joined to the pair of joining plates 13 by welding or the like, and the end of the restraining material 30 is accommodated in the space formed by the wide portion 12 of the core material 10, the pair of joining plates 13, and the reinforcing plate 18.

By placing the insert plate 20 between the core material 10 and the restraint material 30, when a building frame incorporating the buckling restraint brace 100 is deformed during an earthquake, localized damage caused by the restraint material 30 receiving direct pressure from the core material 10 can be prevented.

Here, the materials from which the inner plate 20, the core material 10, and the restraining material 30 are made are set so that the strength and hardness of the inner plate 20 are relatively higher than those of the core material 10 and the restraining material 30.

For example, the type of metal or the type of steel may be changed so that the strength and hardness of the insert plate 20 is relatively high. Examples of metal types include steel, aluminum, stainless steel, copper, titanium, and lead.

When changing the steel type, there are two configurations: the core material 10, the restraining material 30, and the inner plate 20 are all made of one of SS, SN, or SM materials, with the inner plate 20 made of a relatively high-strength and high-hardness SS material, etc.; and the core material 10 and the restraining material 30 are made of one of SS, SN, or SM materials, with the inner plate 20 made of SC material.

Looking at SS materials, there are SS330, SS400, SS490, SS540, etc., with SS400 and SS490 being the most widely used.

Therefore, in a configuration in which the core material 10, restraint material 30, and inner plate 20 are all made of SS material, it is preferable to use SS400 for the core material 10 and restraint material 30 and SS490 for the inner plate 20, as this reduces manufacturing costs.

On the other hand, SC materials include S45C, S50C, S55C, S60C, etc., with S45C being the most widely used.

Therefore, it is preferable to use, for example, SS400 or SS490 for the core material 10 and the restraining material 30, and S45C for the insert plate 20, as this reduces manufacturing costs.

When metal members made of the same metal are brought into contact with each other to form a sliding surface, the sliding surfaces of both metal members undergo plastic deformation as they mesh with each other, which can result in galling or seizing. On the sliding surfaces of metal members made of the same metal, the oxide film on the sliding surface is peeled off, exposing the metal, which is prone to diffusion bonding and welding, and when welded, unevenness can occur on the metal surface. If the hardness of both metals is the same, the unevenness of each metal will mesh with each other, so by making the hardness of both metals different, for example, the relatively harder metal will cut and deform the softer metal, and the repeated cutting will make it smooth.

Therefore, in the buckling restraint brace 100, an insert plate 20 made of a different metal or steel type and having higher strength and hardness than the core material 10 and restraint material 30 is placed between the core material 10 and restraint material 30. This prevents the core material 10 from clashing with the insert plate 20, and the insert plate 20 from clashing with the restraint material 30, when a building frame incorporating the buckling restraint brace 100 is deformed during an earthquake.

In addition, by eliminating the need for a standard butyl rubber unbonding material, after the buckling restraint brace 100 is assembled, the entire brace can be immersed in a water-soluble solution and electrocoated by passing a direct current through it to form a coating.

In conventional buckling restraint braces that use butyl rubber unbonded material, the butyl rubber deteriorates when electrocoated, so each part is spray-painted and then assembled to produce the buckling restraint brace, which requires a lot of production work. Furthermore, if the assembly after spray painting is done by welding, a touch-up rust-preventive paint is applied after welding, but this touch-up rust-preventive paint also requires production work.

The buckling restraint brace 100 allows the entire assembled buckling restraint brace to be electrocoated, eliminating the need for touch-up rust-preventive paint and dramatically improving manufacturing efficiency.

For the above reasons, the insert plate 20 has both the function of preventing localized damage caused by the pressing force that the restraining material 30 receives from the core material 10 and the function of acting as an unbonded material, and therefore can also be called an insert plate that doubles as an unbonded material.

As shown in FIG. 1, the inner plate 20 is attached to the restraining member 30 in the X2 direction and fixed by spot welding, adhesive, etc. Here, the inner plate 20 may be fixed to the core material 10.

As shown in FIG. 4, a gap 25 of, for example, about 1 mm is formed between the inner plate 20 formed on the opposing surface of the restraint member 30 and the core material 10 (opposite the mounting surface of the inner plate 20). Inside this gap 25, a compressive force acts on the core material 10 when the building frame incorporating the buckling restraint brace 100 is deformed, causing high-order mode buckling (wavy deformation) in the out-of-plane direction (weak axis direction) in the narrow width portion 11.

In the buckling restraint brace 100, the insert plate 20 has a relatively high strength and hardness compared to the core material 10, etc., so the thickness of the insert plate 20 can be made as thin as possible. Therefore, the buckling restraint brace 100 formed with the gap 25 has an overall thickness that is as thin as possible.

The restraint member 30 is made of a square steel pipe that is rectangular in cross section. The side of the restraint member 30 to which the inner plate 20 is attached also has a projection hole 30a into which the projection 15 of the core member 10 fits.

On the sides of the core material 10, both sides (sides corresponding to the short sides of the rectangle) of the pair of restraining members 30 are connected by welding or the like to a pair of stiffening members 50 made of steel plates, and the core material 10 is surrounded by the pair of restraining members 30 and the pair of stiffening members 50.

Next, with reference to Figure 5, we will explain the higher-order mode buckling that occurs in the weak axis direction of the core material 10.

The buckling restraint brace 100 is incorporated into the building frame by bolting both ends to connecting jigs provided at the corners of the building frame. When the building frame is deformed during an earthquake, external forces such as horizontal forces during the earthquake enter the ends of the buckling restraint brace 100 through the connecting jigs, and the external force is transmitted as compressive force N from the ends of the core material 10 to the entire area, causing the entire core material 10 to plastically deform, thereby demonstrating its energy absorption performance during an earthquake. In other words, when compressive force N is applied to the core material 10, higher-order mode buckling (wavy deformation) occurs throughout the entire core material 10 in the weak axis direction, and the entire core material 10 is buckled as evenly as possible, allowing the entire buckling restraint brace 100 to demonstrate its overall plastic deformation performance.

As shown in FIG. 5B, a compressive force N acting on the core material 10 causes higher-order mode buckling, and the peaks of the wavy deformation caused by buckling apply a pressing force Q to the inner plate 20.

After the pressing force Q acts on the inner plate 20, it spreads inside the inner plate 20 and acts on the restraining material 30, preventing localized damage to the restraining material 30 due to the pressing force Q.

Note that the configurations described in the above embodiments may be combined with other components, and the present invention is not limited to the configurations shown here. In this regard, changes can be made without departing from the spirit of the present invention, and can be determined appropriately according to the application form.

10: Core material 10a: Wide surface 11: Narrow portion 12: Wide portion 12a: Bolt hole 13: Joint plate 13a: Bolt hole 14: Slit 15: Protrusion 17: Spacer 18: Reinforcing plate 20: Insertion plate (Insertion plate also used as unbonded material)
20a: Projection hole 25: Gap 30: Restraint material (square steel pipe)
30a: Projection hole 50: Stiffener 100: Buckling restraint brace N: Axial force (compressive force)
Q: Pressing force

Claims (6)

A steel plate-shaped core material,
A pair of restraining members made of square steel pipes arranged to face the two wide surfaces of the core material;
An insert plate is interposed between the core material and the restraint material,
A buckling restrained brace, characterized in that the strength and hardness of the insert plate are relatively high compared to the core material and the restraint material. The buckling restraint brace of claim 1, characterized in that the core material, the restraint material, and the insert plate are all made of one of SS material, SN material, and SM material, and the insert plate is made of a material with relatively high strength and hardness. The buckling restraint brace of claim 1, characterized in that the core material and the restraint material are made of one of SS material, SN material, and SM material, and the insert plate is made of SC material. The buckling restraint brace according to any one of claims 1 to 3, characterized in that a gap is provided on the side of the insert plate opposite the attachment surface to the core material or the restraint material for buckling deformation of the core material. A pair of joining plates are fixed to both ends of the core material, and are joined to other members perpendicular to the wide surface,
5. A buckling restraint brace as described in any one of claims 1 to 4, characterized in that a reinforcing plate is fixed to the pair of connecting plates, and an end of the restraint material is accommodated in a space formed by the wide surface, the pair of connecting plates, and the reinforcing plate. A pair of stiffening members connects both sides of the pair of restraining members on the sides of the core member,
The buckling restraint brace according to claim 1 , wherein the core material is surrounded by the pair of restraining materials and the pair of stiffening materials.

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