JPH0615780B2 - Axial variable stiffness material for building frame - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an axial direction variable rigidity material used for a building frame having a vibration control structure, and a member of the member according to an external force such as an earthquake or wind input to the building. It changes rigidity and copes with earthquakes.

[Conventional technology]

Conventionally, in seismic design of high-rise buildings and important structures, dynamic design has been performed to check the safety by calculating the movement of the ground and the response of the building during an earthquake.

Seismic resistant methods include seismic isolation or damping methods in which laminated rubber bearings and dampers are interposed between the building and foundation, methods of consuming seismic energy by destroying non-major components of building components, walls or columns. Provide slits such as
There is a method to adjust the building to the optimum rigidity.

By the way, the confirmation of the safety of a building designed by the current seismic design method during an earthquake is based on the basic idea that the absorbed energy due to the hysteresis characteristic accompanied by plasticization of the structure exceeds the seismic energy acting on the structure. However, this has a reliability problem with respect to the history loop characteristic.

In addition, all of the conventional methods provide a passive seismic resistant structure against natural external forces such as earthquakes and winds, and because the building has a specific natural frequency, resonance phenomena are generated in response to uncertain inputs such as earthquakes. You cannot avoid it.

On the other hand, in the Japanese Patent Application No. 61-112026, the applicant changed the rigidity of the building itself based on the judgment of the response prediction system based on the detected seismic motion instead of the passive seismic resistance method as described above, and the resonance. We propose a seismic control method for the safety of the building, equipment inside the building, and occupants by keeping it outside the area or in a state where there is little resonance.

In the above seismic control method, a control device whose connection state is changed by a computer command is installed between all or part of columns, beams, braces, walls and their joints, or between the building and the foundation or an adjacent building. , Damping the building is done as follows.

An earthquake detector is used to detect the occurrence of an earthquake in a narrow area and a wide area around the building, and the observation data is transmitted to a computer via a wired or wireless communication network. The wide area seismic detector is connected to the seismograph at the existing seismic observation point or a specially installed seismometer by a micro line or a telephone line. The narrow-area seismic sensing device is composed of a seismograph installed around the building or in the surrounding ground, and a vibration sensor installed in the building base or inside the building. The influence of wind force is detected by the vibration sensor inside the building.

Regarding the detected earthquake, the computer determines the scale of the earthquake, analyzes the frequency characteristics, predicts the response amount, etc., bypasses the resonance regarding whether or not to control the building vibration, and the control amount when it should be controlled, It is judged that it gives the optimum stiffness (natural frequency) with a small amount of seismic response.

The computer command is transmitted to the control device of each part of the building, and the control device is operated so that the rigidity of the building becomes the optimum rigidity based on the prediction of the computer. For adjusting the connected state, the fixed state and the released state are adjusted by turning on and off with a hydraulic mechanism, electromagnet, etc., and the hydraulic mechanism is used for the outside of the fixed state, the released state, the introduction of tension force and the fixing at any position. Alternatively, adjustment using a special alloy or the like can be considered.

Further, the vibration sensor arranged in the building can detect the response amount in each part of the building and the actual vibration when the control is performed, and by feeding back this, the control amount can be corrected.

[Object of the Invention]

The present invention is used for a brace or a pillar in a building structure having a vibration control structure, and changes the rigidity of the building structure by changing the rigidity according to an external vibration force such as an earthquake or wind, thereby changing the rigidity of the building structure to prevent an earthquake or wind. Reduce the response of the building due to vibration external force,
The purpose of the present invention is to provide a variable axially rigid material for a building frame, which is suitable for realizing a comfortable living space, operates instantly, and can fully and reliably exhibit its function. .

[Structure of Invention]

The axial variable rigidity material according to the present invention uses a main member bent or bent with respect to the axial direction as an axial force resistance material such as a brace or a pillar, and the curved or bent main member is used as an axial force resistance material in a building frame. In the bending plane, a hydraulic or electric actuator for controlling the axial deformation of the main member by applying a force to the central part of the main member in the direction perpendicular to the axial direction, and the actuator in accordance with the external vibration force The control means for controlling the operation is provided. The axial direction is not the curved or bent material axis of the main member, but the direction connecting the joints at both ends of the main member.

With the above configuration, the amount of axial deformation when an axial force is applied can be controlled by applying a force in a direction perpendicular to the axial direction, and the relationship between force and displacement, that is, rigidity can be made variable. .

The control means is a control program or the like incorporated in a computer or the like, and controls the operation of the actuator so that appropriate rigidity can be obtained. That is, in response to an external vibration force such as an earthquake, the actuator is operated by a control signal from the control means to change the rigidity and connection state of members in each part of the building to change the natural period of the entire building. The resonance can be avoided.

As will be described later, the rate of change in rigidity changes depending on the rise-span ratio due to the bending or bending of the main member, so it is necessary to appropriately select a rise-span ratio that is as efficient as possible.

[Work]

FIGS. 5 (a), (b), and (c) are simplified illustrations of the principle in the case of using an arcuate bending material as the main member of the axial direction variable rigidity material of the present invention.

When an axial force N acts as shown in FIG. 5 (a), in addition to the axial force N, the bending stress M = Ny due to the axial force N acts on the main member.
Occurs, a bending deformation component is added to the axial deformation δ ₁ in addition to the axial deformation component.

As shown in FIG. 5 (b), when a force P is applied to the center of the bending member as the main member in a direction perpendicular to the axial direction, bending stress causes axial deformation δ ₂ .

Therefore, as shown in FIG. 5 (c), the amount of axial deformation δ ₃ can be adjusted by exerting the force P on the bending member on which the axial force N acts. In addition, FIG.
Although (a), (b) and (c) show examples of tensile force, the same applies to compressive force.

The same can be considered when the main member is bent in a mountain shape as shown in FIGS. 6 (a) and 6 (b).

Next, Fig. 7 shows the theoretical development when the main member is a mountain type.
An explanation will be given based on (a) and (b). The symbols used here are as follows.

E: Young's modulus of main member A: Cross-sectional area of main member I: Moment of inertia of area of main member i: Secondary radius of cross-section of main member λ: Slenderness ratio of main member (= 1 / i) l: Of main member Length a: Rise of main member N: Axial force P: Rigidity control force δ _x1 : Axial deformation by N δ _y1 : ridge top deformation by N δ _x2 : Axial deformation by P δ _y2 : Deformation of the mountain top by P δ _x : Sum of δ _x1 and δ _x2 δ _y : Sum of δ _y1 and δ _{y2 In} FIG. 7 (a), δ _x1 and δ _y1 are expressed by equation (1) and
It becomes the formula (2).

δ _x1 = Nl / EA + Na ² l / 3EI (1) δ _y1 = Nal ² / 12EI (2) In Fig. 7 (b), δ _x2 and δ _y2 are respectively expressed by equation (3) and
It becomes the formula (4).

δ _x2 = Pal ² / 12EI (3) δ _y2 = Pl / 48EI (4) From equations (1) and (3), the most efficient rise-span ratio (a / l) to change the rigidity To find), first look at the relationship in Eq. (5).

(Δ _x2 / P) / (δ _x1 / N) = 1/4 {(l / a) (3 / λ) + (a / l)}
(5) When the value of Eq. (5) is maximum, that is, the rise span ratio is in Eq.

At this time, equation (5) becomes equation (7).

Thus, when the spring constant K in the axial direction when the rise span ratio is set to the expression (6) is obtained, the expression (8) is obtained, and P is larger than the spring constant N / δ _x1 when the control force P is not present. You can see that it changes Φ times when it works.

K = N / (δ _x1 + δ _x2 ) = (N / δ _x1 ) Φ = kΦ (8) Here, Φ: coefficient of change in rigidity in the axial direction β: Controlling force coefficient β = P / N (10) The relationship between the coefficient of change Φ of rigidity in the axial direction and the controlling force coefficient β is shown in FIG. From this, it can be seen that when β is negative, that is, when the control force P is actuated so that the axial deformation δ _x with respect to the axial force N becomes small, the rigidity change is large,
For example, when λ = 50, the rigidity becomes about 3.6 times higher with a control force of only 0.2N.

Rise span ratio If the maximum stress δ _max of the main member at the time of is only controlled so that β becomes negative, that is, the rigidity becomes large, for example, approximately in the case of a box-shaped cross-section material, as in formula (11). For example, a cross section that is about three times that of a normal axial force resistance material may be used.

δ _max = N / A (3.12 + 0.306βλ) (11) From the above theoretical development, the mechanical characteristics of the variable rigidity material according to the present invention are as follows.

There is the most efficient rise-span ratio when the change in rigidity is viewed from the control force. In the case of chevron Is the case. The rise-span ratio of the variable stiffness material should be in the vicinity of this.

When the control force is applied in the direction in which the deformation becomes small, that is, in the direction in which the deformation becomes rigid, the change in rigidity is large, and the effect as the variable rigidity material can be more exerted. For example, in the case of a mountain-shaped material, when λ = 50, the rigidity increases by 3.6 times due to the control force of 20% of the axial force.

The cross section of the member used as the variable rigidity material of the present invention may be about three times as large as the cross section required for the linear material when controlling only in the direction in which the rigidity increases.

〔Example〕

 Next, the illustrated embodiment will be described.

FIG. 1 shows an example in which the axially variable stiffness material of the present invention is used as a brace. The main member 1 curved in an arc shape in a plane surrounded by the columns 3 and the beams 4 is arranged diagonally, and both ends thereof are joined to the gusset plate 9 by the pins 8. On the other diagonal line, a hydraulically controlled actuator 2 is provided between the upper corner and the central part of the main member 1, and the expansion and contraction of the actuator 2 can apply a force to the main member 1 in a right angle direction. it can. FIG. 2 shows an example of the structure of the actuator 2 as a control device, in which the hydraulic pressure can be adjusted by the servo valve 7 and the control force can be adjusted accurately and quickly. The piston 6 of the actuator 2 and the main member 1 are connected to each other by sandwiching them with bolts 12 via a pressure plate 11.
By bending or bending the contact surface of the main member 1 with the main member 1, a line can be applied. As the main member 1, steel having an H-shaped cross section or the like is used.

9 and 10 are diagrams for analysis of the above-described embodiment. In the above-described embodiment, the reaction force of the control force acting on the main member 1 by the actuator 2 must be considered, and this reaction force acts on the column 3 and the beam 4. Therefore, when the control is applied, the axial force ΔN is applied to the main member 1 as a brace.

In FIG. 9 which is a simplified version of FIG. 1, h / l = 1
In the case of, it becomes Formula (12).

ΔN = −0.5P = −0.5βN (12) Therefore, N / (N + ΔN) = 1 / (1-0.5β) times,
The spring increase rate changes, and the modified stiffness change coefficient Φ ′ becomes (1
It becomes like the formula 3).

Φ '= Φ / (1-0.5β) (13) This is shown in the graph as the slenderness ratio λ = 50.
Fig. 0.

FIG. 11 is a graph showing the relationship between the axial force N and the axial deformation δ _x (elongation or contraction) when the rigidity is changed by the axial variable rigidity member of the present invention.
In the relation between the axial force N of the brace and the deformation δ _x , the rigidity can be relatively easily changed to Φ ′ = 1 to 3 and the stroke of the actuator is ±
3 cm is enough. Further, this control can be performed by measuring the strain between AB in FIG.

The embodiment shown in FIG. 3 and FIG. 4 is also an example of using as a brace, and two mountain-shaped members are used as a pair as the main member 1, and the central portions of these two mountain-shaped members are tied together. The actuator 13 is attached. In this case, the actuator 13 as a control device is housed in the brace, which makes the device compact. Further, there is an advantage that there is no influence of the reaction force as in the above-mentioned embodiment.

[Effects of the invention] By using it for columns and braces of a building frame with a vibration control structure, the rigidity as a member and the rigidity of the building frame are changed, and the natural period of the building is changed according to individual seismic characteristics, and resonance occurs. It is possible to suppress a large deformation of the building due to the phenomenon.

The rigidity can be continuously changed by controlling the force of the actuator in the direction perpendicular to the axial direction of the main member.

The rigidity is changed by utilizing the shape and deformation of the main member, and unlike the method of changing the connection state of a plurality of members, structurally stable and reliable operation can be expected.

The rigidity of the actuator can be changed instantaneously by the operation of an actuator that is controlled according to the external vibration force such as earthquake motion, and effective vibration control can be performed while responding to the momentary change.

[Brief description of drawings]

FIG. 1 is a front view of a frame showing an embodiment of the present invention, and FIG.
FIG. 3 is a sectional view of the control device portion, FIG. 3 is a front view of another embodiment, FIG. 4 is a sectional view of the control device portion, and FIGS. 5 (a), (b),
(c), FIGS. 6 (a) and (b) and FIGS. 7 (a) and (b) are explanatory diagrams showing the principle, and FIG. 8 is a graph showing the rate of change of rigidity, FIG.
FIG. 10 is a front view showing a simplified example of application to a brace, FIG. 10 is a graph showing the rate of change of rigidity, and FIG. 11 is a graph showing the relationship between axial force and displacement. 1 ... Main member, 2 ... Actuator, 3 ... Pillar, 4 ... Beam, 5 ... Cylinder, 6 ... Piston, 7 ... Servo valve, 8 ... Pin, 9, 10 ... Gusset plate, 11 ... Pressure plate, 12 ... Bolt, 13 ... Actuator, 14 ... Pressure plate, 15 ... Bolt.

Claims (2)

[Claims] Claim: What is claimed is: 1. An axially variable rigidity material which constitutes a building frame having a vibration control structure and whose rigidity changes in response to an external vibration force, wherein a main member curved or bent with respect to the axial direction is an axial direction in the building frame. Used as a force resistance material, hydraulic or electric for controlling the amount of axial deformation of the main member by applying a force to the central portion of the main member in a direction perpendicular to the axial direction in a curved or bent surface. And a control means for controlling the operation of the actuator according to the vibration external force, the variable axial rigidity material of the building frame. 2. The axially variable rigidity material for a building frame according to claim 1, wherein the control device is provided between a pair of main members which are pin-joined to each other at both material ends.