JPH0671602U - Unbonded brace material - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to reduce the weight of buckling stiffeners, improve the economy of unbonded brace materials, and improve workability. [Structure] A brace material 1 is sandwiched between two steel materials as a buckling stiffening material 2, and a fluororesin 11 is inserted to cut friction. When the brace member 1 receives a compressive force, it is constrained from deforming in the out-of-plane direction, so that a stable axial deformation occurs. Pillar 1
The joint portion of the frame 6 and the beam 17 is joined by welding 8 of the bracket 7 and the brace material 1 so that an external force is applied only to the brace material 1. The joint portion between the buckling stiffener 2 and the bracket 7 is provided with a loose hole 10 in the axial direction of the buckling stiffener 2 and fastened with a bolt 18. Further, since an out-of-plane force due to the stiffening reaction force is applied to the bracket 7, the reinforcing rib 9
To provide.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an unbonded brace material used for construction and civil engineering structures.

[0002]

[Prior art]

 An unbonded brace structure is one of the brace structures in building structures. The unbonded brace consists of a brace material and a buckling stiffener, and the friction between them is intentionally cut.

By intentionally cutting friction, the burden of external force becomes clear, and the adverse effects on each other when the brace material and the buckling stiffener behave integrally can be eliminated. Since the stiffening material behaves independently and can exhibit its individual performance sufficiently, there are advantages such as efficient utilization of the material.

The point of such an unbonded brace lies in an efficient buckling stiffening method or its structure, and conventionally, there are the following ideas, for example.

(1) RC stiffening type Naoji Nagao et al .: Experimental study of unbonded braces coated with H-shaped steel by RC (Part 1: Outline of experimental plan), Summary of Academic Lectures at the Architectural Institute of Japan (Hokuriku) 1992 August [Reference 1], and Naoji Nagao et al .: Experimental study of unbonded braces coated with H-section steel by RC (Part 2: Test results and consideration), Architectural Institute of Japan Annual Conference Lecture Summary (Hokuriku) 1992 In August [Reference 2], as shown in FIG. 8, a bracing material 1 made of H-shaped steel was used as a buckling stiffening material with a polyethylene film sheet as an unbonded material (not shown) interposed. Experimental methods and test results of unbonded braces coated with reinforced concrete 12 are shown.

Also, Ichiro Inoue et al .: Design for buckling stiffening of concrete wall with unbonded flat steel braces, Architectural Institute of Japan Structural Paper Report No. 432, February 1992 [Reference 3], FIG. As shown in a) and (b), the flat steel brace 1 is unbonded and built into the reinforced concrete wall 13, and the reinforced concrete wall 13 is used as a buckling stiffener for the steel brace 1. The design, experimental results, etc. are shown.

(2) Stiffening style of double steel pipe Katsuhiko Imai et al .: Study on stiffening effect of double steel pipe (Part 1, Axial loading test method), Abstracts of Academic Lectures at the Architectural Institute of Japan (Tohoku) 1991 In September [Reference 4], as a stiffening method for circular steel pipes subjected to compressive force, a double steel pipe in which an axial force member 14 and a stiffening member 15 are separated as shown in Figs. 10 (a) and (b). Has been proposed and an analysis targeting unbonded braces is being conducted.

[0008]

[Problems to be solved by the device]

 In the conventional RC stiffening type unbonded brace, in order to prevent the buckling of the brace material 1, the RC part has a considerably large cross section, which poses a problem of economical efficiency and workability.

Further, in the double steel pipe stiffening type, the cross section of the inner steel pipe 15 as a stiffening material is not so large as compared with the RC stiffening type, but the axial force member 14 and the inner steel pipe 15 as a brace member are There is an unavoidable gap between them, which is not preferable from the viewpoint of buckling stiffening. Further, the installation method of the inner steel pipe 15 is also difficult and there is a problem in workability.

The present invention is intended to solve the above-mentioned problems in the conventional unbonded brace, and to reduce the weight of the buckling stiffener, improve the economical efficiency of the unbonded brace, and improve the workability. It is an object.

[0011]

[Means for Solving the Problems]

 The unbonded brace material of the present invention sandwiches the brace material forming the brace body with two buckling stiffeners from both sides in the weak axis direction to substantially reduce the friction between the brace material and the buckling stiffener. The buckling stiffener does not generate an axial force substantially by cutting it. As the buckling stiffener, use a steel material that can be made lighter than conventional RC stiffeners and is easy to handle such as processing and mounting.

The ordinary brace material is designed as a member that resists tensile force, but the buckling stiffening material restrains the deformation of the brace material in the direction perpendicular to the axial direction, so that stable axial deformation occurs. As an unbonded brace material, it can also resist compressive force. Therefore, the brace material exhibits stable restoring force characteristics even under the action of repeated loads such as an earthquake.

It is desirable that there is substantially no gap between the brace member and the buckling stiffener, and in that case, it may be possible to interpose a fluororesin or the like between them to reduce friction. To be

With respect to the deformation of the structure frame, the brace member bears an external force in the form of an axial force, and the buckling stiffener member does not substantially bear an axial force. To do this, the buckling stiffeners can be separated from the frame, but in consideration of mounting, etc., the braces can be attached to the structure frame or the metal fittings attached to the frame in the axial direction via loose holes. There are methods such as slidable bolt connection.

Further, by connecting the buckling stiffeners on both sides of the brace member, it is possible to significantly increase the sectional rigidity as the buckling stiffener.

[0016]

[Action]

 (1) Comparison with conventional RC stiffening type First, we examined how lighter the RC stiffening type could be. As an example of RC stiffening, comparison was made with the A-1 test piece that exhibited good restoring force characteristics in Documents 1 and 2 described in the section of the related art.

The dimensions of the test specimen to be compared are as follows (see FIG. 8). Brace material Cross section H-150 x 150 x 9 x 9 mm (Cross section area A = 38.8 cm ² ) Steel type SM50 (σ _y = 3.3 tf / cm ² ) Material length L = 3000 mm RC stiffening material Cross section 250 x 250 mm Main bar 16-D10 Hoop muscle DG- @ 75 The relationship between the required rigidity and strength of stiffening material and the strength of brace material is shown as follows from Document 1. P _E / P _y ≧ 1 / [1-4 (δ _e / L) / (F _y / P _y )] (1)
^{_{Here, P E (= π 2 EI}} / L 2): stiffener Euler buckling P _y: yield axial force F _y of brace (= 4M _y / L): Length L across simple support stiffeners on loading can Plane out centralized load M _y: stiffener bending yield strength [delta] _e: unavoidable eccentricity, clearance, etc. between the brace member and the stiffener, to conversion based on deflection table the effect of initial imperfection Quantity L: Length of brace material Fig. 7 shows the relationship of equation (1) above with a curve (solid line). Below the curve, there is a danger that overall buckling will precede axial yielding of brace material. The area is shown, and the upper side shows the safety area.

The rigidity and strength of the stiffener before cracking in the RC stiffener of the test body were approximately the following values. P _E / P _y = 11 F _y / P _y = 0.027 For the unbonded brace material of the present invention, a buckling stiffener having the above value as the lower limit is selected.

Various combinations that satisfy the above values can be considered depending on the sectional shape, dimensions, material strength, etc. of the buckling stiffener. For example, as shown in FIG. Two 50 × 90 × 9 × 13 mm channel materials 2a (SM50, σ _y = 3.3 tf / cm ² , I = 4180 cm ⁴ , Z = 334 cm ³ ) are used to connect the buckling stiffeners 2 to each other. If it is not, P _E / P _y = 15 F _y / P _y = 0.229, which satisfies the above value. The brace material 1 was a flat steel 1a (cross section 250 × 16 mm, σ _y = 3.3 tf / cm ² ) having the same cross-sectional area.

Comparing the weights in this cross section, the weight is reduced by about 1/2 for the stiffening material and about 1 / 1.8 for the total weight including the brace material.

In the above example, since a commercially available steel material is used for the buckling stiffener, the buckling stiffener has a cross section with a slightly excessive safety factor, and the welding assembly reduces the weight. A buckling stiffener can be realized.

(2) Effect of making the gap between the brace member and the buckling stiffener substantially zero δ _e shown in the above equation (1) is the eccentricity of the brace member, the brace member and the buckling stiffener. It shows the initial deflection that includes two of the gaps between the material. Therefore, by setting the gap between the brace material and the buckling stiffener to be 0, δ _e becomes smaller, and more efficient buckling stiffening is possible (see the chain double-dashed line in FIG. 7).

[0023]

【Example】

 FIG. 1 shows a basic structure of the unbonded brace material of the present invention, in which a brace material 1 is sandwiched between two steel materials as a buckling stiffening material 2, and the brace material 1 and the buckling stiffening material. The gap between the two is substantially zero.

When the brace material 1 receives a compressive force, the brace material 1 is restrained from being deformed in the out-of-plane direction by the buckling stiffening material 2, so that the brace material 1 undergoes stable axial deformation. Therefore, the brace material 1 exhibits stable restoring force characteristics as shown by the solid line in Fig. 2 even under the action of repeated load such as an earthquake. The broken line in Fig. 2 is the case without the buckling stiffener 2.

FIG. 3 shows a concrete example of the unbonded brace material of the present invention. Further, details of the portion A to which the unbonded brace material is attached are shown in FIGS. 4 (a) and 4 (b). There is.

Since the brace material 1 constituting the main body is buckled and stiffened and only the axial force needs to be borne, a flat steel 1a, for example, is considered as an economically excellent material with a small number of manufacturing processes. To be

In this case, the buckling stiffener 2 is required to have rigidity in the weak axis direction outside the surface of the frame, and has a shape excellent in economic efficiency. In this embodiment, the channel member 1a is shown in FIG. 5 (a). It is used as shown. In addition, for example, an H-shaped steel 1b as shown in FIG. 5 (b), a double web material 1c composed of two webs and two flanges by welding assembly as shown in FIG. 5 (c), and the like are conceivable. .

The joints of the columns 16 and the beams 17 with the frame made of the frame assembly are joined by welding 8 of the bracket 7 and the brace material 1 protruding from the frame so that the external force enters only the brace material 1. .

The joint between the buckling stiffener 2 and the bracket 7 is provided with a loose hole 10 in the axial direction of the buckling stiffener 2 and fastened with bolts 18 or the like. The bracket 7 is provided with a reinforcing rib 9 because an out-of-plane force due to the stiffening reaction force is applied to the bracket 7.

In this embodiment, no gap is provided between the brace member 1 and the buckling stiffener member 2, but a fluororesin 11 or the like can be inserted to cut the friction.

Further, if the buckling stiffeners 2 sandwiching the brace member 1 are connected from both sides, the stiffening force of the two buckling stiffeners 2 can be expected, and the stiffening effect is doubled.

[0032]

Effect of the Invention Compared with the conventional RC stiffening, the buckling stiffening member can be made lighter in weight and easier to handle such as processing and mounting.

As an unbonded brace material, it exhibits stable restoring force characteristics even under the action of repeated loads such as earthquakes.

By making substantially no gap between the brace member and the buckling stiffener, the buckling stiffening effect is enhanced, and a highly reliable and economical design is possible.

By connecting the buckling stiffeners on both sides of the brace member, it is possible to significantly increase the sectional rigidity as the buckling stiffener.

[Brief description of drawings]

FIG. 1 is a sectional view showing a basic structure of an unbonded brace material of the present invention.

FIG. 2 is a diagram showing a restoring force characteristic of the unbonded brace material of the present invention.

FIG. 3 is a front view of a frame showing an embodiment of the unbonded brace material of the present invention.

4 (a) is an enlarged view showing details of a portion A in FIG. 3, and FIG. 4 (b) is
It is a BB sectional view of (a).

5 (a) to 5 (c) are views showing variations of the unbonded brace material of the present invention in a cross section perpendicular to the axial direction.

FIG. 6 is a cross-sectional view perpendicular to the axial direction of the unbonded brace material of the present invention used for comparison with the conventional RC stiffening type unbonded brace.

FIG. 7 is a graph relating to design conditions for a buckling stiffening material in an unbonded brace material.

FIG. 8 is a sectional view perpendicular to the axial direction showing an example of a conventional RC stiffening type unbonded brace.

FIG. 9 shows an example of an RC stiffening type unbonded brace using a conventional RC wall as a stiffener. (A) is a front view of the frame and (b) is a cross-sectional view of the brace member position. is there.

FIG. 10 shows an example of a conventional unbonded brace for stiffening a double steel pipe, where (a) is a sectional view before bending and (b) is a sectional view after bending.

[Explanation of symbols]

1 ... Brace material, 1a ... Flat steel, 1b ... H-section steel, 1c ... Double web material, 2 ... Buckling stiffening material, 2a ... Channel material,
7 ... Bracket, 8 ... Welding, 9 ... Reinforcing rib, 10 ... Loose hole, 11 ... Fluororesin, 12 ... Reinforced concrete, 13 ... Reinforced concrete wall, 14 ... Axial force material, 15 ...
Stiffener, 16 ... Pillar, 17 ... Beam, 18 ... Bolt,

Claims (4)

[Scope of utility model registration request] 1. A brace member is sandwiched between two buckling stiffeners made of steel from both sides in the weak axis direction, and friction between the brace member and the buckling stiffener member is substantially cut off. An unbonded brace material characterized in that the buckling stiffener is substantially free of axial force. 2. The buckling stiffener is a bolt that is slidable in the axial direction of the buckling stiffener through a loose hole with respect to a structure frame to which the brace member is attached or a metal fitting attached to the frame. The unbonded brace material according to claim 1, which is joined. 3. The unbonded brace material according to claim 1, wherein a gap is not substantially formed between the brace material and the buckling stiffening material. 4. The unbonded brace material according to claim 1, 2 or 3, wherein buckling stiffening materials on both sides of the brace material are connected to each other.