JP2019065532A - Axial force resistant member - Google Patents

Abstract

To provide an axial force resistant member capable of improving plastic deformability and energy absorption capacity under tensile load while maintaining high buckling resistance under compressive load.SOLUTION: An axial force resistant member includes a brace core material 2 which bears tensile and compressive loads, and a buckling restraining material 3 which prevents buckling of the brace core material 2 at the time of compression in which the brace core material 2 is yield-deformed by tensile and compressive loads. The brace core material 2 has a yield part 2A to be yield-deformed by tensile and compressive loads, and has fixing parts 2B, 2C to the buckling restraining material 3 at both end parts of the yield part 2A. At the end of the fixed parts 2B, 2C, there are provided attachment parts 4 and 5 to the structural member. A notch part 7, 7 is provided at an edge part at a boundary between a horizontal flange 6a of the fixing part 2B and the attachment part 4. A buckling reinforcing rib 8 is provided on a side face of the attachment part 4. The buckling reinforcing rib 8 has a face touch with the end face of the vertical flange 6b of the fixing part 2B on a vertical plane perpendicular to the axis perpendicular direction of the brace core member 2, which intersects with the notch parts 7, 7.SELECTED DRAWING: Figure 4

Description

  The present invention is also used as a viscous damper to reduce the vibration of a building during a large earthquake, a damping damper such as a buckling restrained brace, a joint such as a bridge fall prevention device of a bridge, and also a beam or booth material of a building. With regard to joints such as axial force resistant members, the present invention is intended to improve plastic deformation capacity and energy absorption capacity under tensile load while maintaining high buckling resistance particularly against compressive load.

  As a design method for beam-to-column connections of structures, form a plastic deformation at a position slightly away from the beam-to-beam connection in the material axial direction, and yield the plastic deformation before the beam-to-beam connection. Therefore, there is known a design method for avoiding fracture or brittle fracture of welds of column-beam joints in a large earthquake (reduced beam section (RBS) design).

  In this design method, a notch or a hole is provided at a position slightly away from the joint of the column and the beam in the material axis direction of the beam to partially reduce the cross section of the beam, thereby leading any member in advance. By yielding and forming a plastic hinge, it is possible to avoid catastrophic failure of the beam-to-column connection such as fracture or brittle failure of the weld of the beam-to-beam joint.

  In addition, it is incorporated between layers of the main frame of the structure, and absorbs seismic energy according to the elastic area and elastic-plastic area of the core material against tensile and compressive loads in the axial direction of the material during earthquakes, thereby shaking the building. The invention of buckling restraint braces to reduce is known. In addition, it is known that there is an invention of an anti-fallout device installed between an end of a bridge girder of a bridge and an abutment or pier supporting the end of the bridge girder to absorb an earthquake impact and prevent the bridge girder from falling from the abutment or pier. It is done.

  For example, in Patent Document 1, at a joint between a column and a beam of a steel structure in which the beam (2) is joined to the column (1), reinforcement is made along the material axial direction of the beam (2) to the beam flange (3) Beam-to-column connection having a plate (5) and having notches (6) and (7) at positions slightly away from the beam-to-beam connection of the reinforcing plate (5) and the beam flange (3) The invention is disclosed.

  According to the invention, the portion having the notch (6) of the beam (2) has a lower bending resistance than the other portions, so that the portion having the notch (6) has an edge ahead of the other portion when subjected to seismic force. By yielding the member, it is possible to avoid breakage or brittle fracture of the welded portion of the beam-to-column joint.

  Further, in Patent Document 2, a core material (2) made of steel having an axial force and having a substantially cruciform cross section, and a core material (2) which yield-deforms a member due to a tensile load and a compressive load are restrained and compressed. Four restraints (3) made of steel and having a cross-sectional mountain shape to prevent buckling of the core (2) and a pair of restraints (3) sandwiching the core (2) through the spacer (4) The invention of a buckling restrained brace is disclosed which comprises a plurality of joining bolts (5) to be joined and a buffer (7) disposed between the core (2) and the restraint (3).

  In particular, in the middle part of the core material (2), by making the diameter small in the axial direction of the material over a predetermined length, a yield part (2A) which is yield deformed by tension and compression load is formed, An attachment portion (2B) to a structural member such as a beam is formed.

  Further, bolt holes (8) through which joining bolts (5) are inserted are formed in the constraining member (3), the spacer (4) and the mounting portion (2B), and further, at one end of the constraining member (3) The bolt holes (8a) of the mounting portion (2B) are formed in long holes elongated in the material axial direction so as to be able to cope with the plastic deformation of the core material (2).

  The buckling-restrained brace is incorporated between the main frame of the building, and when a large displacement occurs in the building, the core material (2) yields and deforms the members to absorb seismic energy and reduce the shaking of the building. It can be done.

  And in patent document 3, the middle part of the brace core material (2) and the brace core material (2) of the steel plate by which the rib (22) for reinforcement was attached to the both ends is pinched in the thickness direction, and the deformation The invention of the buckling restrained brace which consists of a steel buckling restrained material (3) which restrains is disclosed.

  The buckling-restrained brace is incorporated between the main frames of the building, and when a large displacement occurs in the building, the brace core (2) of the steel plate yields and plastically deforms to absorb seismic energy. , Can reduce the shaking of the building.

JP 2002-88912 A Unexamined-Japanese-Patent No. 2006-328688 JP 2000-265706 A Patent Document 1: JP-A-2015-145670

  In the invention of the joint of a column and a beam of Patent Document 1, the reinforcing plate (5) is attached in the material axial direction of the beam through a position having a notch (7) on the side surface of the beam flange (3) However, since the reinforcing plate (5) is a single piece, and a portion of the reinforcing plate (5) having the notches (7) is continuously attached in the material axial direction of the beam, the flange (3) Even if the notch (7) is provided at the edge of the frame, it can not be said that the plastic deformation capacity and the energy absorption capacity to the bending tensile load increase as desired.

  In addition, in order to increase the plastic deformation capacity and energy absorption capacity for bending tensile load, it is necessary to provide notches (6) as shown in the reinforcing plate (5), which significantly reduces the strength against bending compressive load. There is a risk of

  In the invention of the buckling restrained brace of Patent Document 2, the yield portion (2A) of the core material (2) is plastically deformed only in the range of the long hole (8a) formed in the attachment portion (2B) of the core material end. Therefore, when an unexpected tensile load that causes plastic deformation exceeding the range of the long hole (8a) is applied to the yield portion (2A), it can not be coped with. In addition, since the attachment portion (2B) is formed in a cross shape in cross section, the plastic deformation capacity of the attachment portion (2B) is considered to be smaller than the yield portion (2A).

  Therefore, at the time of the unexpected large earthquake as described above, the main frame of the building to which the attachment portion (2B) is joined suffers fatal damage such as weld fracture. In addition, when the attachment portion (2B) is formed in a flat plate shape to give plastic deformation ability, there is a possibility that neck buckling failure may occur at an unexpected compression load.

  The present invention has been made to solve the above problems, and in particular while maintaining high buckling capacity against compressive load, it has high plastic deformation capacity and energy absorbing capacity under tensile load, and is unexpectedly large. An object of the present invention is to provide an axial force resistant member in a joint portion which can cope with earthquakes sufficiently.

  The present invention is an axial-resistance member of a joint including a plastic deformation portion which has a cross-sectional defect and which is plastically deformed in a portion having the cross-sectional defect due to a tensile load, and the side surface of the plastic deformation It is characterized in that a buckling reinforcing rib is attached which is in contact with each other in a plane intersecting with the cross-sectional defect and which is continuous in the acting direction of the tensile load.

  The plastically deformed portion may be formed in a flat plate shape, and a notch or a through hole may be formed as a cross-sectional defect at the edge of the plastically deformed portion.

  The plastic deformation portion is formed in a substantially H-shaped or I-shaped cross section from a pair of flanges arranged in parallel and between the pair of flanges and a web continuous with the flange, and a cross section at the edge of the flange A notch or a through hole may be formed as a defect. Furthermore, the plastic deformation capability of the plastic deformation portion can be enhanced by forming a cross-sectional defect in the web and attaching a pair of buckling reinforcing ribs.

  According to the present invention, when the design load of the joint is exceeded with respect to the tensile load at the time of a large earthquake, the plastic deformation portion precedes any portion to yield a member at the portion having the cross section defect portion By deforming, it exerts high deformability and energy absorbing ability, while for compressive load, it can avoid neck-breaking failure of joints by buckling reinforcement rib, and it is mainly used for building beams and braces. Or, it can be used as a damping member of a bridge, a drop bridge preventing device, and the like.

FIG. 1A is an embodiment of the present invention, and FIG. 1A is a plan view of an axial force resistant member used for a buckling restrained brace of a building, an apparatus for preventing a bridge from falling bridge, etc. FIG. FIG. 2 (a) is a cross-sectional view taken along the line I--a of FIG. 1 (a), and FIG. 2 (b) is a cross-sectional view of FIG. FIG. 2 (c) is a cross-sectional view taken along the line HA in FIG. 1 (a), and FIG. 2 (d) is a cross-sectional view taken along the line II in FIG. 1 (a). FIG. 3 (a) is a plan view and FIG. 3 (b) is a front view. FIG. 4 (a) is a plan view of the joint before breaking, and FIG. 4 (b) is a front view thereof. FIG. 5 (a) is a plan view of a state in which plastic deformation occurs under tensile load, and FIG. 5 (b) is a front view thereof. Fig. 6 (a) is a plan view of a joint that is plastically deformed and broken under a tensile load, and Fig. 6 (b) is a front view of the joint. FIG. FIG. 7 (a) is a perspective view of the joint before breaking, and FIG. 7 (b) is a perspective view of the joint after breaking. It is. FIG. 8A is a plan view, and FIG. 8B is a front view of the modification of the joint portion of the axial force resistant member illustrated in FIG. Fig. 9 shows a joint portion of the axial force resistant member shown in Fig. 8, Fig. 9 (a) is a plan view of the joint portion plastically deformed under a tensile load, and Fig. 9 (b) is a front view thereof. . FIG. 10 (a) is a plan view of a joint portion which is plastically deformed and broken under a tensile load, and FIG. 10 (b) is a front view thereof. FIG. FIG. 11 (a) is a perspective view, FIG. 11 (b) being an illustration of the mounting hardware to be attached to the side surface portion of the abutment and the like and the joint portion of the axial force resistant member attached as the falling bridge prevention device. 11 (c) is a perspective view of the mounting part which is plastically deformed and broken under a tensile load, and FIG. 11 (d) is the use of two mounting plates. It is a perspective view of the example in the case of having been. FIG. 12 (a), (b), (c) is an end perspective view of an axial force resistant member used as a brace material or a beam material of a main frame of a building. Fig. 13 (a) is a front view of a beam-to-column joint, and Fig. 13 (b) is a cross-sectional view thereof. . FIG. 14 (a) is a front view of a beam-to-column joint, and FIG. 14 (b) is a cross-sectional view of the axial-force-resistant member incorporated as a beam member of a main frame of a building.

  FIGS. 1-11 is one Embodiment of this invention, and illustrates the axial-force-resistant member used as an anti-vibration brace of a building, and the bridge fall prevention apparatus of a bridge. In the figure, the axial force resistant member 1 restrains the brace core 2 at the time of compression by constraining the brace core 2 which bears tensile and compressive loads and the brace core 2 which is yield-deformed by the tensile and compressive loads. The four buckling restraint members 3 are provided to prevent the

  The brace core 2 is formed of a steel plate having a predetermined length, and is formed in a substantially cruciform shape in cross section by welding and fixing the plate along the material axis direction to the center of both surfaces of one plate.

  Further, by making the diameter smaller than both ends in the middle part in the material axial direction, a yield part 2A which is yield deformed by tension and compression load is formed over a fixed length in the material axis direction, and both ends of the yield part 2A are seats The fixing portions 2B and 2C for fixing to the bending restraint material 3 are provided.

  Furthermore, mounting portions 4 and 5 to be mounted to structural members such as columns and beams are formed at the end portions of the respective fixing portions 2B and 2C. The mounting portions 4 and 5 have the same width and the same plate thickness as the horizontal flange 6 of the fixing portions 2B and 2C having a substantially cruciform cross section, and are formed in a flat plate continuous in the same plane as the horizontal flange 6 .

  In addition, at the boundary between the horizontal flange 6 of the fixing portion 2B and the mounting portion 4, cutaway portions 7 and 7 having an arc shape are formed. The notches 7, 7 are formed symmetrically on both side edges of the horizontal flange 6.

  Further, buckling reinforcing ribs 8 and 8 are symmetrically mounted at the centers of both surfaces of the mounting portion 4. The buckling reinforcement rib 8 is a vertical plane perpendicular to the axial direction of the brace core 2 which intersects the notches 7 and 7, the end faces abut each other (face touch), and the material axis of the brace core 2 It is formed continuously in a fixed length in the direction. The code | symbol 8a is an abutting surface of the buckling reinforcement ribs 8 and 8. As shown in FIG.

  In the embodiment, the vertical flange 6b of the fixing portion 2B doubles as one buckling reinforcing rib 8, and the end surface of the buckling reinforcing rib 8 abuts on the end surface of the vertical flange 6b of the fixing portion 2C. (Face touch), and is formed continuously in a fixed length in the material axial direction of the brace core 2.

  As described above, the mounting portion 4 is formed in a flat plate shape, and the notches 7 and 7 are formed at both ends of the boundary between the mounting portion 4 and the horizontal flange 6. When a tensile load having a size exceeding the yield deformation capacity of the yield portion 2A is applied, the portion having the notches 7 and 7 of the attachment portion 4 yields and plastically deforms in the tensile direction (FIG. 4) , 5).

  When a compressive load equivalent to a tensile load is applied to the brace core 2, the pair of buckling reinforcing ribs 8, 8 attached at the centers of both surfaces of the attachment portion 4 intersect the notches 7, 7. By carrying out surface touch with a perpendicular surface in the direction perpendicular to the axis of the brace core 2, the mounting portion 4 is reinforced so as not to cause a buckling failure (see FIG. 3).

  The buckling restrained material 3 is formed of angle steel, and is assembled in a substantially cruciform cross section so as to sandwich each piece of the brace core 2 at each corner of the brace core 2 and yield at the time of tension and compression. It restrains the deformed yield portion 2A, and restrains buckling of the yield portion 2A at the time of compression.

  Further, the buckling restraint material 3 is formed to have a length corresponding to the total length of the yield portion 2A and the attachment portion 2C of the brace core 2, and the fixing portion 2C and the spacer 9 are formed by the buckling restraint materials 3 and 3 adjacent to each other. They are fixed to each other by a plurality of bonding bolts 10 disposed at a predetermined pitch in the material axis direction.

  Furthermore, the bolt hole 11 in which the joint bolt 10 is inserted is formed in the buckling restrained material 3, the spacer 9 and the fixing portions 2B and 2C, and in particular, the bolt hole of the fixing portion 2B at one end side of the buckling restrained material 3 In order to correspond to the yield deformation of the restraint portion 2A of the brace core 2, the long hole 11a is formed in the material axial direction.

  The thus constructed axial force resistant member 1 is incorporated as a buckling restrained brace between the layers of the main frame of the building, and when a large displacement occurs in the building, the yield portion 2A of the brace core 2 undergoes yield deformation. Can absorb seismic energy and reduce the shaking of the building.

  In particular, when a tensile load exceeding the yield deformation ability of the yield portion 2A acts on the brace core 2, the portion of the mounting portion 4 having the notches 7 and 7 yields and plastically deforms, and in some cases, fractures. By doing this, it is possible to avoid fatal damage such as breakage of the welds of the main frame.

  In addition, when an unexpected compressive load is applied, the mounting portion 4 can be reinforced so as not to cause a buckling failure by the pair of buckling reinforcing ribs 8 and 8 mounted at the centers of both surfaces of the mounting portion 4.

  FIGS. 8 to 10 illustrate the joint portion of a modification of the axial force resistant member illustrated in FIGS. 1 to 7, and in particular, the brace core 2 is formed to have the same width and the same thickness over the entire length, The entire brace core 2 is formed so as to absorb seismic energy by plastic deformation with respect to axial compression and tensile load.

  Moreover, there is no buckling restraint material 3, and the buckling reinforcement rib 8 is formed symmetrically over the entire length at the center of both surfaces of the brace core 2 so that it is formed so as not to buckle under axial compression load. .

  FIGS. 11 (a) to 11 (d) illustrate a mounting member attached to the side surface of a main structure such as an abutment, for example, to which an end of an axial force bearing member such as an anti-fall bridge is connected. Notches 7 and 7 are formed vertically symmetrical at the upper and lower edge portions of one mounting plate 12a. In addition, a plurality of pairs of seats formed in contact with each other (face touch) in the vertical plane intersecting the upper and lower notches 7 on both sides of the mounting plate 12a and having a predetermined length in the acting direction of the axial compression load. Bent reinforcing ribs 8, 8 are attached in one or more stages.

  When the tensile load transmitted through the axial force bearing member (not shown) reaches an unexpected load, the mounting plate 12a to which the end portion of the axial force bearing member is connected is the upper and lower sides of the mounting plate 12a. By breaking after plastic deformation at the portion having the notches 7 formed symmetrically at the edge, fatal damage to the main structure due to an unexpected tensile load can be avoided in advance. Further, with respect to the axial compression load transmitted through the axial force bearing member, both sides of the mounting plate 12a abut (face touch) in a vertical plane intersecting with the notches 7 and the axial compression load The buckling failure of the mounting member 12 can be avoided in advance by the resistance of the plurality of upper and lower pairs of buckling reinforcing ribs 8 formed in a fixed length in the action direction of.

  The mounting plate 12a to be fractured can be designed in consideration of the yield strength and tensile strength of the material used, so that a plurality of compact mounting members can be provided by using a plurality of sheets according to the design load.

  FIG. 11 (d) shows an embodiment in which two mounting plates 12a of the mounting member shown in FIG. 11 (a) are used, and two mounting plates 12a and 12a are mounted in parallel. The notches 7 and 7 are vertically symmetrical at the upper and lower edge portions of each mounting plate 12a.

  In addition, a plurality of pairs formed in contact with each other (face touch) in the vertical plane intersecting the notches 7 on the inner side surface of each mounting plate 12a 12a, and formed to have a fixed length in the acting direction of the axial compressive load The buckling reinforcement ribs 8, 8 are mounted in one or more stages. According to the said modification, it can be set as a highly strong attachment member by the reason of having attached two attachment plates 12a.

  FIGS. 12 to 14 show another embodiment of the present invention, which is an axial resisting member used as a brace material or a beam of a principal skeleton between layers of the main skeleton of a building, and a principal skeleton incorporating the axial resisting member. Is illustrated.

  In the figure, the axial force resistant member 13 is formed of an H-shaped steel, and a pair of notches 7 are formed at the left and right edges of the upper and lower flanges 13a, 13a at the axial end of the H-shaped steel. . The notches 7 are formed in the left-right symmetry and at the same position of the upper and lower flanges 13a, 13a inward of a fixed length in the material axial direction from the end face of the flange 13a.

  Further, a pair of buckling reinforcing ribs 8, 8 are attached to the outside of the upper and lower flanges 13a, 13a in the same vertical plane as the web 13b between the upper and lower flanges 13a, 13a. A pair of buckling restraint ribs 8, 8 abut each other (surface touch) in a plane perpendicular to the axis direction of the H-section steel intersecting the notches 7, 7, and the material axial direction of the H-section steel It is formed in a fixed length.

  As illustrated in FIG. 12 (b), a plurality of buckling reinforcing ribs 8 may be attached in the axial direction of the H-shaped steel. Further, the plastic deformation capability can be further enhanced by providing the web 13b with the through holes 13c as cross-sectional defects and attaching a pair of buckling reinforcing ribs 8, 8 to one side or both sides of the web 13b. Reference numerals 14 and 15 are columns and beams that constitute the main frame.

  In such a configuration, when an unexpected tensile load acts on the axial force resistant member 12 at the time of a large earthquake, the portion (plastically deformed portion) having the notches 8 and 8 of the upper and lower flanges 12a and 12a yields By plastic deformation, it is possible to absorb seismic energy and avoid fatal damage such as breakage of the welds of the main frame.

  Further, even if a compressive load having a size corresponding to the above-mentioned tensile load is applied, the pair of buckling reinforcing ribs 8, 8 compensates for the strength reduction of the upper and lower flanges 12 a, 12 a due to having the notches 7, 7. Thus, the buckling failure of the axial force resistant member 12 can be avoided.

  The present invention solves the problem of neck buckling in the joint of members by the plastic deformation ability of a specific part for tensile load exceeding the design load while maintaining the buckling resistance by the buckling reinforcement rib. Can.

1 Axial force resistant member 2 Brace core material
2A yield part
2C fixed part 3 buckling restraint material 4 mounting part 5 mounting part
6a horizontal flange
6b Vertical flange 7 Notched section
7a Through hole (cross section defect)
8 buckling reinforcement rib
8a Contact surface (surface touch)
9 Spacer
10 joint bolt
11 bolt holes
11a bolt hole
12 Mounting member
12a mounting plate
13 Axial force resistant member
13a upper and lower flange
13b Web
14 pillars
15 beams

Claims (6)

  It is an axial resisting member having a cross sectional defect and having a plastic deformation that plastically deforms in the cross sectional defect due to a tensile load, wherein a side surface of the plastic deformation crosses the cross sectional defect with each other An axial resisting member characterized in that a buckling reinforcing rib is attached which is in contact with and continuous in the acting direction of a tensile load.   The axial force resistant member according to claim 1, wherein the plastic deformation portion is formed in a flat plate shape, and a cross-sectional loss portion is formed at an edge of the plastic deformation portion.   The shaft deformation resistant member according to claim 1, wherein the plastic deformation portion is formed in a substantially H-shaped cross section from a pair of flanges arranged in parallel and a web continuous with the flange between the pair of flanges. A shaft-resistant member characterized in that a cross-sectional defect portion is provided at the edge of the flange.   4. The shaft-resistant member according to claim 3, wherein the web is also provided with a cross-sectional defect and a buckling reinforcing rib.   The axial force-resistant member according to any one of claims 1 to 4, wherein a notch or a through hole is formed as the cross-sectional defect portion.   The axial force resistant member according to any one of claims 1 to 5, wherein a plurality of the buckling reinforcing ribs are attached to one side or both sides of the plastic deformation portion.