JP4883639B2 - Reinforcement structure of tubular metal flat plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aseismic shear panel which can stably maintain needed yield shearing proof strength after the yield until reaching a large deformation area by securing a shearing yielding load by increasing a shearing buckling load of a substantially rectangular flat metal plate mainly receiving the shearing force. <P>SOLUTION: A reinforcing structure 1 of the substantially rectangular flat metal plate indicates a tubular flat plate, being a structural bisect anisotropic body, in which framed peripheral frame body 3 and inside parallel reinforcing members 4 are arranged. When the flat plate receives the shear force from the peripheral part, obverse/reverse flat metal plate 2 yields by the y-axis directional shear force in the leafy areas surrounded by the peripheral frame body and the inside reinforcing members. After that, the bearing force is maintained against the x-axis directional force until reaching the large deformation area contributed by the inside reinforcing members. Plasticization of the tubular flat plate is limited to the leafy areas for a while and is still partly in an elastic state even after the shear yield, and stable hysteretic nature against the load repeatedly applied in a positive-negative alternating manner is obtained. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention provides an early shear seat for a substantially rectangular metal flat plate that mainly receives a shearing force and constitutes all or a part of a structural wall, a stud, a boundary beam, a crossing portion of a strut for vibration suppression or earthquake resistance. Reinforcement structure intended to increase the plastic deformation capacity of a flat plate by avoiding bending and securing a shear yield load and maintaining stable shear strength without decreasing in the large deformation region after yielding It is.

  A substantially rectangular metal flat plate subjected to shearing force can maintain a yield strength in the process in which subsequent buckling deformation grows even if a shear buckling load can be secured, and to have a stable hysteretic property with respect to a load that is repeated alternately in positive and negative directions. For this reason, it is necessary to considerably increase the shear buckling load, and the width-thickness ratio of the flat plate becomes small. As a result, a large number of stiffeners are arranged in a lattice shape to subdivide the entire flat plate region.

Since it is necessary to increase the shear buckling load of the metal plate relative to the yield shear load, the thickness of the metal plate can be increased by using a material with an extremely low yield point stress relative to the shear strength required for the design. There is a method to avoid early shear buckling and increase the plastic deformation ability after yielding. In addition, various proposals have been made to maintain the proof strength of a metal flat plate subjected to a shearing force, such as a wall plate incorporating a viscoelastic material, a method of joining a wall plate and a building part.
Japanese Patent Laid-Open No. 2004-270208 Japanese Patent Laid-Open No. 2005-042423 Japanese Patent Laid-Open No. 2006-037586 Japanese Patent Laid-Open No. 2006-342622 Tomomi Kihara / Shingo Torii “Design of damping structure using steel plate wall with extremely low yield point” Architectural Technology November 1998

  The problem to be solved is the reinforcement to increase the shear buckling load by increasing the shear rigidity of the flat plate, which is mainly subjected to shearing force, to increase the shear buckling load and to stably maintain the yield strength after shear yielding. A method is proposed to improve the plastic deformation ability even for a thin metal flat plate, and to make a shear earthquake-resistant panel that has a stable hysteresis property even with a load that is repeated alternately in positive and negative directions.

  As a substantially rectangular metal plate that mainly receives a shearing force, a frame-shaped frame composed of solid or tubular rectangular cross-section members is provided on the four sides, and a solid or tubular rectangular cross-section member having the same thickness as the frame material is disposed therein, By attaching a front and back metal flat plate to the component member to form a tubular body flat plate, the shear buckling load is increased, and a decrease in the yield strength immediately after yielding is prevented, and after that, stable mechanical properties are obtained without reducing the shear strength. Intended.

  Equation 1 shown below is a balanced differential equation of a flat plate subjected to a shearing force, and the flat plate stiffness D is usually treated as the bending stiffness of the unit plate width as shown in the second formula. Except for the Poisson's ratio component of the bending stiffness, the stiffness is basically the torsional stiffness represented by the third equation and is directly related to the shearing force. In order to increase the torsional rigidity as a tubular flat plate, it is necessary to harden the periphery of the flat plate, but this correspondence is relatively easy, and the tubular flat plate is considered to be a powerful structure as a shear earthquake resistant panel.

  The number 2 shown below indicates the rate of rigidity reduction of a tubular flat plate having an overall thickness T composed of a thin plate having a thickness t with respect to a solid cross-section flat plate having a thickness T as α. Although the plate thickness t constituting the body is 10% of the total thickness T and the rigidity is reduced by about 50%, the converted plate thickness of the tubular plate is about 80 of the total thickness when the cube root of the rigidity is the plate thickness. Since the tube yields a significant reduction in the shear yield load and the apparent width-to-thickness ratio, the flat plate of the tubular body has stable mechanics in the large deformation region after shear yielding. Properties can be secured.

  A structural model for satisfying the mechanical requirements of the tubular flat plate is shown in FIG. A frame-shaped frame 3 composed of solid or tubular rectangular cross-section members is provided on the four sides, and one or a plurality of solid or tubular rectangular cross-section members 4 having the same thickness as the frame material are provided in parallel with one of the peripheral frames. It is arranged in layers to form an intermediate layer, and further, a metal plate 2 is attached to both the front and back surfaces of the intermediate layer to form a tubular plate. By forming a structural orthotropic body, deformation after shear yielding It is possible to maintain the shear yield load of the front and back metal flat plates even with respect to the increase in the thickness.

  In addition to the internal reinforcing material that is arranged in layers on the premise of an anisotropic reinforcing structure, the member is divided perpendicularly to the reinforcing material as necessary, with respect to the tubular flat plate having an arbitrary rectangular shape. In order to achieve stable hysteresis for repeated repeated positive and negative alternating loads, it is possible to reduce the bending deformation to the outside of the flat plate surface that expands and grows after yielding against large shear deformation. To.

  For a tubular flat plate composed of thin plates, a metal body, a paper body, a wooden body, sandwiched between front and back metal flat plates and partly or entirely in the gap between the surrounding four-sided frame and the internal reinforcing material or internal reinforcing material, Filled with rubber body and various foams and constrains deformation of the metal flat plates on both sides, maintaining the shape of the tubular flat plate, maintaining high torsional rigidity and stable growth of shear deformation after yielding Try to have mechanical properties.

Figure 2 is an explanatory diagram for examining torsional stiffness, (a) figure is an operation diagram of the torsional couple M _T applied from the periphery of the square double layer metallic flat plate 1, it is (b) Fig. The shear stress τ flowing on both the front and back sides of the thin tubular flat plate is shown. (C) of FIG is filled with foam 5 of E = 3kN / cm ² therein a flat cross section which arranged frame member 3 of 90mmx16mm the peripheral portion in 900mmx900mm, (d) drawing frame material is intact This is an example in which the inside of the front and back flat metal plate 2 is hollow.

FIG. 3 is a diagram showing the initial stiffness D _{xy to} which the torsional couple is applied in a ratio with a flat plate having a solid cross section as a whole. The curve marked with ● is when the foam is filled with a tubular flat plate with a frame width of 90 mm. It should be noted that it is approximately 60% larger than the rigidity of the solid section. The curve marked with ▼ that gradually declines as the deformation progresses is when the inside of the tubular flat plate surrounded by the frame material is hollow, and the cause of the drop is due to the fact that the metal flat plates on both the front and back sides cannot keep parallel due to twisting . Even with a frame width of 30 mm indicated by a circle, it is possible to ensure approximately 30% rigidity of a solid cross-section material, but sufficient rigidity cannot be ensured if there is no peripheral frame indicated by a dotted line.

  FIG. 4 shows the flow of force of a typical tubular flat plate 1 after shear yielding. The principal stress components that balance the shear force acting on the peripheral frame are the diagonal tension and dotted line shown by the solid line. It is decomposed | disassembled with the compressive force shown by. With the shear deformation after yielding, a buckling waveform with peaks and valleys grows in the diagonal direction of the solid line, and the corner portion of the frame 3 is drawn toward the center of the flat plate by the diagonal compression force shown by the dotted line, and the yield strength after yielding The frame structure around the flat plate to avoid this is a major feature of this structure. The following three examples including this example are tubular flat plates having a size of 900 mm × 900 mm and a total thickness T = 19.2 mm constituted by flat plates having a thickness of 1.6 mm on the front and back surfaces.

FIG. 5 shows the influence of the frame-shaped peripheral frame on the mechanical properties after plate yielding, and shows the dimensionless index of yield shear stress σ _y and yield shear strain γ _y including the following examples. . The width of the frame material surrounding the periphery is 90 mm, □, 75 mm is marked with ●, and 50 mm is marked with ○, and the three reinforcing members arranged in parallel inside are 50 mm wide. By securing the peripheral frame width to some extent, the shear strength after yielding is maintained without decreasing, but when the frame width is narrowed, the yield strength immediately after yielding decreases. The dotted line shown at the bottom is when the outer periphery is surrounded by a flange of 150 mm × 16 mm protruding from the flat plate, and it can be seen that there is no direct effect of maintaining the shear strength after yielding.

  FIG. 6 shows a typical form of the present reinforcing structure in which the internal reinforcing members 4 are arranged in parallel in one direction to form an anisotropic flat plate. The number and interval of the reinforcing members are determined from the viewpoint of the rigidity of the entire tubular flat plate and the buckling stiffening of the metal flat plate 2 on both the front and back surfaces. When this flat plate receives a shearing force from the peripheral part, the metal flat plates on both the front and back surfaces are first yielded by a shearing force in the y-axis direction in a strip-shaped region surrounded by the peripheral frame member 3 and the internal reinforcement 4 arranged in parallel. Then, it is considered that the proof stress gradually increases and balances against the shearing force in the x-axis direction by the reinforcing material.

  FIG. 7 is an example of analysis to show the mechanical behavior of this anisotropic reinforcing structure. The dimensions and number of internal reinforcing members were examined for the same tubular flat plate as in the previous example. An example of ●, an example of three with a width of 75 mm, and an example of four with a width of 50 mm are shown by □. According to the orthotropic reinforcement, even if the number or size of the reinforcing material is changed, it is hardly affected, and the shear yield load determined by the front and back metal flat plates hardly changes. The dotted line is the result of a flat plate with a 25 mm wide reinforcing material arranged in a grid with three vertical and horizontal lines. The strength of the reinforcing material has increased from the beginning of yielding, and the yield strength has increased.

Equation 3 is a so-called anisotropic flat plate balanced differential equation having different rigidity in the orthogonal direction. As for each coefficient on the left side of the balanced differential equation, the first and third terms are bending stiffnesses, and the second term is a geometric mean of both bending stiffnesses and is mainly torsional stiffness _Dxy . Reinforcement that emphasizes anisotropy in the orthogonal direction in order to stabilize the mechanical properties after flat plate yielding will leave an elastic region in part of the flat plate even after yielding. By not doing so, mechanical stability after shear yielding can be achieved.

  FIG. 8 shows the mechanical balance of the front and back metal flat plates in a state in which shear deformation has progressed after yielding. The metal flat plates 2 on both the front and back surfaces are strip-shaped between the peripheral frame member 3 and the internal reinforcing member 4. It is considered that the oblique tension acts in a distributed manner in the region, and the peripheral frame material and the internal reinforcing material cooperate with each other. An orthotropic reinforcement structure is effective in controlling the growth of out-of-plane deformation related to cyclic hysteresis characteristics by minimizing the influence of internal reinforcement on the shear yield load determined by the metal plates on the front and back surfaces. It is a simple method.

  FIG. 9 shows the growth of bending deformation out of the plane of the tubular flat plate subjected to the shearing force as a ratio of the total thickness T. ● The solid line of the mark is the result of the arrangement of three reinforcing members of 50 mm width as in the previous example, and the dotted line is the one that restrains the deformation of the front and back metal flat plates by filling the gap between the frame material and the reinforcing material with foam. Compared to the overall thickness T, out-of-plane deformation is kept low. ○ Deformation is when the thickness of the frame and reinforcement is increased, □ is when the internal reinforcement is increased and the interval is narrowed, and it is possible to further suppress out-of-plane deformation without changing the shear yield load. it can.

FIG. 10 is an explanatory diagram of a stud that is an assembly type stud-type shear panel mainly for seismic reinforcement of an existing building, and the unit panel 1 is composed of two upper and lower faces. (A) The figure is a unit panel of 900 mm × 900 mm, which is composed of a peripheral frame 3 of 75 mm × 12 mm and five reinforcing members 4 of 30 mm × 12 mm, and the front and back metal flat plates 2 are 0.8 mm thick. (B) The figure shows a 2250mmx900mm columnar shear panel composed of two 900mmx900mm unit panels, with the external reinforcement 6 angled 2L _s -75x75x6 from the outer surface, and the panels and the upper and lower force application parts. It is fixed with a flat plate of 150mmx6mm.

  Fig. 11 shows the numerical analysis results for the above example. The curve with □ indicates that the peripheral frame material and internal reinforcement are SS400 steel, and ● indicates that only the internal reinforcement is 6063-T6 aluminum alloy material. Yes, when all are made of an aluminum alloy material, the mark is ◯. Since the rigidity of the tubular flat plate is related to the arrangement of the front and back metal flat plates, regardless of the material of the frame or reinforcement, there is no problem in maintaining the yield strength after shear yielding. In view of the growth of the out-of-plane bending deformation of the flat plate indicated by the dotted line, it is necessary to consider the rigidity of the metal material.

FIG. 12 shows a 2,500 mm × 1,000 mm columnar type shear earthquake-resistant panel. The metal plate 2 on both sides is a low yield point steel LY225 with a thickness of 6 mm and a yield point stress σ _y = 21 kN / cm ² . The peripheral frame material 3 constituting the tubular flat plate is a 75 mm × 50 mm rectangular cross-section member, and the four internal reinforcement members 4 are a 50 mm × 50 mm cross-section square tube member having a thickness of 3.2 mm and a solid cross-section member. (B) The figure is an assembly drawing sandwiched between 75 mm × 12 mm strip-shaped rectangular flat plates 6 from the outside of the parallel frame on the assumption that a large axial force is received, and all of the inter-column constituent members excluding the front and back metal flat plates are SS400 mild steel.

  FIG. 13 shows the result of the analysis of the above example. The mark ◯ indicates the axial force P = 0, the mark ● indicates the result of the axial force P = 2,000 kN with the outer reinforcing member, and the inner reinforcing member is the square tube member. The result is that the internal reinforcing material is a solid cross-section member at a force P = 2,000 kN. The dotted line in the figure shows the growth of out-of-plane deformation at the center of the longitudinal frame material. However, because the tubular flat plate can be increased in overall thickness and increased in rigidity, it can undergo out-of-plane deformation in the same way as conventional grid rib reinforcement. The shear yield load determined by the flat plates on both the front and back sides can be secured, and stable mechanical properties can be obtained without lowering the proof stress even in the subsequent large deformation region.

FIG. 14 shows the tensile test results showing the mechanical properties of the metal materials taken up in the analysis. The two types of steel materials distinguished by the plate thickness difference are mild steel SS400 and the yield point stress is σ _y = 30 kN / cm ² , which is low. The yield point stress of the yield point steel LY225 is σ _y = 21 kN / cm ² , and the Young's modulus of both is E = 20,500 kN / cm ² , which is indicated by a solid line in the figure. The aluminum alloy material 6063-T6 is represented by a dotted line with a yield point stress degree of σ _y = 21 kN / cm ² and a Young's modulus of E = 7,200 kN / cm ² .

  The tubular flat plate of the present invention is very strange when considered as a flat plate that forms a thin tubular body with respect to a flat cross-section flat plate, just as an H-shaped cross-section member and a box-shaped cross-section member exist with respect to a rectangular cross-section member. It is not a thing. Moreover, since the corresponding rigidity is the torsional rigidity of the flat plate subjected to the shearing force, it is sufficient that the metal flat plates on both the front and back surfaces are parallel and the shear flow is maintained without breaking the tubular body. It is considered to be a highly practical structure that can be easily manufactured as a shear earthquake resistant panel.

  Considering that the tubular flat plate of the present invention can be expected to have high rigidity as a tubular member and the shear yield load of the flat plate is that of a thin plate constituting the tubular member, a flat plate having a small apparent width-thickness ratio is obtained. It behaves as if it is a metallic material with an extremely low yield stress, and is an optimal structure to ensure shear yield load and stable mechanical behavior after yielding. Since the tubular flat plate is a thin metal flat plate and can be constructed regardless of the material type, it will open the way for weight reduction of the shear earthquake resistant panel.

  Regarding the production of tubular flat plates, the front and back metal flat plates are attached to the frame-like frame surrounding the four sides and the internal reinforcement to form the tubular flat plate, which is basically attached with a metal adhesive. If the front and back metal flat plates are thin, use screwing together on the bonding surface or overlap the reinforcement from the outside to prevent peeling, and if the front and back metal flat plates are weldable, the one side of the tubular body flat plate Or by making the outer peripheral portion of the frame material into a welded state, it can be made into a spindle-type hysteresis property against the seismic force applied to the positive and negative alternating in the large deformation region as a panel damper.

It is a block diagram of the periphery frame of this tubular body flat plate, and an internal reinforcement. It is an effect | action figure of the twist couple applied to a tubular body flat plate from a peripheral part. Example 1 It is explanatory drawing of an analysis result about the torsional rigidity of a tubular body flat plate. It is a balance diagram of the frame-like frame and the oblique tension that becomes prominent after yielding. (Example 2) It is explanatory drawing of the analysis result regarding the mutual effect of a surrounding framework and an internal reinforcement. It is a block diagram of the internal reinforcement material used as a structural orthogonal anisotropic body. (Example 3) It is explanatory drawing of the analysis result regarding the internal reinforcement material used as orthogonal anisotropy. It is the conceptual diagram which showed the tension field stress flow of the tubular body flat plate. Example 4 It is explanatory drawing of the analysis result regarding the out-of-plane bending deformation of a tubular body flat plate. It is explanatory drawing of the column-type shear earthquake proof panel of an assembly system. (Example 5) It is explanatory drawing of the analysis result regarding the tubular body flat plate comprised with a thin plate. It is explanatory drawing of a stud type | mold tubular body flat plate and bending shear force. (Example 6) It is explanatory drawing of the analysis result of this structure whose front and back metal plates are low yield point steel. It is the stress-strain relationship figure of the metal raw material handled by the numerical analysis in this specification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tubular flat plate which receives shear force 2 Metal flat plate which comprises both front and back surfaces 3 Peripheral frame of tubular flat plate 4 Reinforcement material inside peripheral frame 5 Flat filler such as foam 6 Outer reinforcement of tubular flat plate

Claims (3)

  As a substantially square tubular flat plate that receives shearing force mainly in the flat plate surface, a frame-shaped frame consisting of solid or tubular rectangular cross-section members is provided on its four sides, and the same thickness as the frame material is provided inside the peripheral frame One or more tubular rectangular cross-section members are arranged in layers in parallel with one of the two side frames to form a structurally orthotropic body, and further, a hollow portion in which a metal flat plate is attached to both the front and back surfaces of the structure. Reinforcement structure of a shear seismic panel that significantly increases the torsional rigidity of the flat plate as a tubular body, secures the shear yield load determined by the front and back metal plates, and maintains the shear strength after yielding.   As a rectangular tubular flat plate that mainly receives shearing force in the flat plate surface, a frame-shaped frame composed of solid or tubular rectangular cross-section members is provided on the four sides around it, and a solid or tubular tube with the same thickness as the frame material inside the peripheral frame Although one or more rectangular cross-section members are arranged in layers in parallel with the longitudinal frame on both sides to form a structural orthogonal anisotropy body, the longitudinal intermediate portion of the member is divided and solid or tubular rectangular cross-section members are orthogonal Furthermore, it is a tubular flat plate including a hollow portion that is parallel to a metal flat plate attached to both the front and back surfaces of the structure, ensuring a shear yield load determined by the front and back metal flat plate and shear strength after yielding Reinforcement structure of shear seismic panel to maintain   For substantially square tubular plates or rectangular tubular plates that receive shear forces mainly on the flat plate surface, it is attached to the frame material on the four sides surrounding the structural orthotropic body and the members arranged in layers inside the frame. In this way, a strip-shaped rectangular flat plate or a strip-shaped rectangular plate with protruding flanges is attached and reinforced as necessary from both the front and back sides or one side of the tubular flat plate, and the bending deformation to the outside of the flat plate surface that expands and grows after yielding is kept low The shear seismic panel according to any one of claims 1 and 2, wherein a stable hysteretic property with respect to a load repeated alternately and a shear yield load determined by the front and back metal plates are secured and the shear strength after the yield is maintained. Reinforcement structure.

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