JP2545504B2 - Seismic intensity detection method for control - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention controls various systems to automatically operate when a large earthquake occurs in order to prevent the spread of damage and the occurrence of secondary disasters. The present invention relates to a control seismic intensity detection method applicable to a control seismometer for taking safety measures such as stopping.

(Problems to be Solved by Conventional Technology and Invention) Currently, seismographs for control are used for transportation, city gas, electric power,
From various industrial facilities such as waterworks to household appliances such as oil stoves, it is incorporated as an automatic emergency stop device in the event of a large earthquake, ranging from very high precision to simple ones. However, most of these conventional seismometers for control belong to the maximum acceleration detection type.

However, depending on the earthquake, the maximum acceleration of the earthquake motion does not always correspond to the damage to the facility to be controlled, and even if the maximum acceleration is large, the damage to the facility may be minor, as described below. It has been confirmed by vibration experiments.

Therefore, if you try to control only by detecting the maximum acceleration,
Even if there is no damage to the facility or a very slight earthquake, the seismograph issues a control signal and controls the facility to stop its functioning. In addition, unnecessary control may cause a great loss. Therefore, a highly reliable control seismometer capable of performing control according to the degree of damage has been desired.

The above-mentioned conventional seismograph for control detects the maximum acceleration of the earthquake motion and issues a control signal from the viewpoint that the force applied to the structures of various facilities by the earthquake motion is the cause of the destruction, but the structure does not always Not only those that are destroyed by force, but in the case of a tenacious structure, the vibration energy of the structure during an earthquake contributes to the destruction. For example, in 1961 GW
Hausner states that it is the vibrational energy of the structure that contributes to the ultimate failure of the structure at the time of the earthquake, and has published the concept of the SI value as a measure of the strength of the earthquake. This SI value is defined as the average value of the response speed in the range of 0.1 seconds to 2.5 seconds of the natural period of the velocity response spectrum of the one-degree-of-freedom vibration system with a damping constant of 20%. It has been reported that the relationship between the SI value and the seismic intensity obtained by analyzing the velocity response spectrum has a better correlation than the relationship between the maximum acceleration and the seismic intensity.

FIG. 1 shows the results obtained by the inventors of the present invention for the SI values of a large number of strong motion records in Japan and the United States, and the relationship between the SI values and the maximum acceleration and the earthquake damage. Damage occurs when the SI value exceeds approximately 25 cm / s, and if it is smaller than this value, there are many cases where damage does not occur even if the maximum acceleration is large, and it was found that the SI value and the damage are highly correlated. .

This means that conventional seismometers for control, which try to control only by detecting the maximum acceleration, can control even an earthquake without damage as described above. In addition, this means that although the acceleration is smaller than the maximum acceleration setting value that should be detected by the seismograph, the SI value is large, and when an earthquake that is likely to damage the structure occurs, the The total shows that the necessary safety measures mentioned above cannot be taken.

The present invention was devised in view of the above points, that is, the strength of seismic motion is detected not only as the maximum acceleration corresponding to the force applied to the structure but also as the SI value corresponding to the vibration energy of the structure. By doing so, the purpose is to make it possible to perform control according to the degree of damage.

By the way, since the SI value is given by the above definition, if it is to be calculated by using the acceleration obtained by the seismograph, a very large-scale device will be required as described later.

The present invention aims to solve the above-mentioned problems, as well as the above-mentioned problems.

(Means for Solving the Problem) To explain the means for solving the above-mentioned problem, first, the seismic intensity detecting method for control according to the first aspect of the invention satisfies the equation of motion of the vibration system with one degree of freedom, and There are two calculation units that use acceleration as an input signal and velocity response as an output signal.
Each of the calculation units has a damping constant of 20% and a natural period of 1.5 seconds and 2.5 seconds, respectively, and inputs the acceleration signal of seismic motion from a common accelerometer to each calculation unit. The speed response is calculated from moment to moment, and the SI value, which is the index of the vibration energy of the structure during an earthquake, is approximated by the value obtained by multiplying the larger value of the speed responses of these calculation units by a constant 0.73. And the acceleration is compared with each set value, and the control signal is issued when at least one side is equal to or more than each predetermined value.

Also, in the seismic intensity detecting method for control of the second invention, in the first invention, in place of the SI value, the speed response having the larger value among the speed responses of the above-mentioned calculation unit is used for the structure during the earthquake. The speed response corresponding to the SI value of the index of vibration energy possessed is compared, and the speed response and the acceleration are compared with the respective set values, and at least one side issues a control signal when the respective predetermined values or more. Use as a summary.

Further, the seismic intensity detection method for control of the third invention is 1
The calculation unit that satisfies the equation of motion of the vibration system with degrees of freedom, receives the acceleration of earthquake motion as an input signal, and outputs the speed response as an output signal. The calculation unit sets the damping constant to 20% and the natural period to the speed. Corresponding to the flat portion of the response spectrum, input the acceleration signal of the seismic motion from the accelerometer to the above calculation unit to obtain the speed response from moment to moment, and multiply the velocity response by a constant 0.73 to determine the structure The gist is to approximate the SI value of the vibration energy index that has, compare the SI value and the acceleration with the respective set values, and issue a control signal when at least one of the predetermined values on one side is exceeded. .

Further, in a fourth aspect based on the third aspect, in place of the SI value, the speed response and the acceleration of the arithmetic unit described above are compared with respective set values, and at least one side is equal to or more than a predetermined value. The point is to issue a control signal to the.

(Action) Generally, the natural period characteristic of the velocity response spectrum of a seismic wave has a substantially flat shape in a long period that rises upward in a short period. Therefore, if this characteristic is used, SI can be calculated without calculation according to the above definition. The value can be easily approximated.

That is, the acceleration signal of the seismic motion by the common accelerometer,
The damping constant of 20% and the natural period are input to each of two sets of calculation units with 1.5 seconds and 2.5 seconds, and the speed response of each is obtained moment by moment, and the larger value is multiplied by a constant 0.73, or the acceleration is calculated. The acceleration signal of the seismic motion from the meter has a natural period of 2.5.
It is possible to obtain an approximate value of the SI value by inputting it to a set of arithmetic units corresponding to a flat portion of the velocity response spectrum such as seconds and multiplying the value of the velocity response by a constant 0.73.

Therefore, by comparing the SI value thus derived and the acceleration with the respective set values, if the control signal is issued when at least one side is equal to or higher than the respective predetermined value, the maximum acceleration is equal to or higher than the set value. Of course, if very large,
Although the maximum acceleration is smaller than the set value above, a control signal is issued when the SI value is greater than or equal to the set value, and various systems are controlled and automatically driven to prevent the spread of damage and the occurrence of secondary disasters. It is possible to take safety measures such as stopping.

On the other hand, since the SI value is obtained by multiplying the selected speed response by a constant as described above, it is possible to calculate this instead of the SI value described above by associating the set values to be compared. It is possible to compare the response with the respective set values together with the acceleration, and to issue a control signal when at least one side is equal to or more than the respective predetermined values.

(Example) Next, this invention is demonstrated in detail with reference to an Example.

First, FIG. 2 is a system diagram of an embodiment of the arithmetic unit 1 used in the method of the present invention. Motion equation of the calculating portion 1 1-degree-of-freedom vibration system, i.e. ^{+ 2ωh + ω 2 x = -} ... (1) x: displacement to the mass of ground constituting the building Z: displacement of the ground with respect to a fixed coordinate in space omega = 2π / T: Natural angular frequency, T: Natural period h: Damping constant is satisfied, and the acceleration (ie) of seismic motion is used as an input signal and the velocity response (ie) is used as an output signal. The configuration of FIGS. 2 (a) and 2 (b) will be described in detail. The calculation unit 1 sequentially includes first and second integration units on the output side of an addition unit 2 that calculates the sum of a plurality of input signals. A signal (2ω) obtained by multiplying the output () of the first integrator 3 by twice the product of the natural angular frequency (ω) and the damping constant (h) is provided.
h), the signal (ω ² x) obtained by multiplying the output (x) of the second integrator 4 by the square of the natural angular frequency, and the acceleration signal () of the earthquake motion by the accelerometer 5 are added to the adder 2 Input signal, and these input signals are inverted before being input to the adder 2 as shown in FIG. 2 (a), or to the output side of the adder 2 as shown in FIG. 2 (b). In this case, the sum signal is inverted, so that the equation of motion of the one-degree-of-freedom vibration system is satisfied, and the output signal of the first integrator 3 is the velocity response signal. In FIG. 2 (a), reference numeral 6 is a reversal portion of the acceleration signal () of the seismic motion by the accelerometer 5, and 7 is an output () of the first integrator 3 and a natural angular frequency (ω) and a damping Multiply twice the product of constants (h) and
A multiplication unit that inverts this to generate a signal (−2ωh),
Reference numeral ⁸ denotes a multiplication unit that multiplies the output (x) of the second integration unit 4 by the square of the natural angular frequency and inverts it to generate a signal (−ω ² x). When the output signal of 3 is the speed response signal (), the input side of the first integrator 3 is expressed as follows, so that in the input side of the first integrator 3, the following equation =-2ωh- ω ² x (2) is satisfied, and therefore, the equation of motion of the one-degree-of-freedom vibration system represented by the above equation (1) is satisfied. Further, unlike the multiplication units 7 and 8 of FIG. 2A, the multiplication units 7 ′ and 8 ′ of FIG. 2B generate signals (2ωh) and (ω ² x) that are not inverted, and add them to the addition unit 2 and The inverting section 6'inverts between the integrating sections 3 of 1 to satisfy the equation (2) on the input side of the first integrating section 3 as in the configuration of FIG. 2 (a). is there. The configuration of FIGS. 2 (a) and 2 (b) is as described above in (2).
Although the expression is literally satisfied, the output signal of the first integrator 3 may be (-) because the absolute value of the speed response can be obtained after that. However, since the acceleration signal of the seismic motion may be positive in any direction, the reversing unit 6 for the acceleration signal of the seismic motion shown in FIG. 2A can be omitted. The components such as the adder unit 1 in the above configuration can be easily realized by an appropriate electric circuit, and if the above-mentioned calculation can be performed in real time or at a speed close to this, it can be realized by software in a microcomputer or the like. It is also possible to realize the components as described above. The natural angular frequency and the damping constant can be easily set by changing the value of the circuit element or the software constant. In addition, the calculation unit 1 may have any configuration as long as it can obtain the speed response signal from time to time in real time or at a speed close to this, using the acceleration signal of the seismic motion from the accelerometer 5 as an input signal.

If a large number of the above calculation units 1 are used, according to the above defined equation
SI value can be calculated. That is, for example, as shown in FIG. 3, a large number of arithmetic units 1 having an attenuation constant of 20% and a natural period set in small increments of 0.1 seconds to 2.5 seconds (for example, in 1/100 second increments) are constructed. The SI value can be calculated by inputting the respective speed response signals from a large number of calculation units 1 to the average value calculation unit 11 via the absolute value calculation unit 9 and the maximum value detection unit 10. However, this method requires a large-scale device and is not practical.

Therefore, in the first invention, generally, the maximum value of the velocity response of the one-degree-of-freedom vibration system due to seismic motion is a function of the natural period and has a rising shape in a short period, but becomes flat in a long period of several seconds or more. The SI value is approximated as follows by utilizing the seismic wave characteristic that the value shows a substantially constant value.

That is, in the first invention, the shape of the velocity response spectrum is
As shown in the figure, it is simplified, and the value of the vertical axis at the corner is taken to be the larger value of the maximum values of the velocity response with a natural period of 1.5 seconds or 2.5 seconds, and is approximated by the following equation.

That is, since 1.75 / 2.4 = 0.73, the SI value is approximated by multiplying the larger speed response value by a constant 0.73.

Figure 6 (a) shows the SI value calculated strictly based on the definition.
This is a comparison between the SI value (exact value) and the SI value (approximate value). As can be seen from this figure, the correlation between the two is extremely high,
Therefore, it is understood that the SI value can be calculated as an approximate value with practically sufficient accuracy by the speed response signals in the two sets of the calculation units 1.

FIG. 4 is a system diagram showing an example of a configuration for calculating the SI value (approximate value) described above. Reference numeral 12 is a maximum value detection unit, and 13 is a multiplication unit of the constants.

Although the above method approximates the SI value by the two sets of operation units 1a and 1b, the method described below is one set of operation units 1a and 1b.
To obtain an approximate value of SI value.

Therefore, the configuration is based on, for example, the configuration shown in FIG.
The absolute value calculation unit 9a can be deleted.
That is, in this example, the SI value is approximated by the following equation using the velocity response with a natural period of 2.5 seconds.

It should be noted that the natural period used for approximation is not 2.5 seconds as described above, but an appropriate natural period of the portion where the velocity response spectrum has a flat shape can be used.

Fig. 6 (b) compares the approximate value obtained by this method with the SI value calculated strictly. As can be seen from this figure, the correlation between the two is comparable to that in Fig. 6 (a). Although it is slightly low, it is sufficiently high. Therefore, it can be seen that the SI value can be approximated with sufficient accuracy for practical use by the speed response signal in the arithmetic unit 1b even in this method using one set of arithmetic unit 1b.

In the present invention, however, the SI value (or speed response) approximated as described above and the acceleration signal from the accelerometer 5 are compared with their respective set values, and control is performed when at least one side has a predetermined value or more. It is configured to emit a signal.

For example, specifically, the acceleration set value A ₁ is larger than the acceleration (for example, about 250 cm / s ² ) at which the conventional maximum acceleration detection seismometer emits a control output, for example, a value 40 corresponding to a severe earthquake.
0 cm / s ² and the SI value set value SI ₁ is, for example, 2
Set to 5 cm / s.

When the acceleration of the seismic motion obtained by the accelerometer 5 is 400 cm / s ² or less at these set values, that is, when the set value A ₁ is not reached, the SI value is 25 cm / s or more, that is, the set value SI ₁ or more. If the acceleration signal is 400 cm / s ² or more, the control signal is issued regardless of the SI value.
To prevent the spread of damage and the occurrence of secondary disasters, it is possible to take safety measures such as controlling various systems and automatically stopping the operation.

In other words, the above-mentioned operation is the acceleration at which the conventional maximum acceleration detection type seismometer outputs a control output, for example, about 250 cm / s ² ~
Even in the case of an earthquake in the range of 400 cm / s ² , the SI value is above the set value SI
If it is less than ₁ , it means that the control output is not generated, that is, in the case of a strong structure, there is no damage or in the case of an extremely slight earthquake, it is necessary not to control the system that is not necessary. Because you can
A large loss due to such unnecessary control can be prevented.

Next, a specific configuration example for performing the above control operation will be described.

In the system diagram shown in FIG. 7, reference numeral 5 is an accelerometer, 1a, 1
b sets the damping constant to 20% and sets the natural period
These are the calculation units set to 1.5 seconds and 2.5 seconds.
The output signals of 1a and 1b are input to the comparing units 14a and 14b via the absolute value calculating units 9a and 9b, respectively, and are compared with equal set values in the comparing units 14a and 14b. This set value corresponds to the above set value SI ₁ .

The acceleration signal from the accelerometer 5 that does not pass through the calculation unit 1 is input to the comparison unit 14c via the absolute value calculation unit 9c, and the comparison unit 14c compares it with the set value A ₁ .

Based on the above configuration, in the example of FIG. 7A, the comparison output signals of the comparison units 14a, 14b, 14c are input to the logical sum unit 15 and the output of the logical sum unit 15 is used as a control output. I am trying. Further, in the example of FIG. 7 (b), the acceleration signal is input to another comparing section 14d, and the setting value is inputted in the comparing section 14d.
Set value A ₂ that is smaller than A ₁ (for example, 80
It is configured to be compared with cm / s ² ).

Then, the comparison output signals of the comparison units 14a, 14b, 14c are input to the logical sum unit 15, and the comparison output of the comparison unit 14d is output via the holding unit 16 together with the output of the logical sum unit 15 and the logical product unit. It is used as an input signal of 17, and the output of the AND unit 17 is used as an output for control via the holding unit 18.

As described above, the SI value is approximated by multiplying the larger value of the maximum values of the velocity response for the natural period of 1.5 seconds and 2.5 seconds by the constant 0.73, and the obtained SI value and the set value SI
₁ is compared with the absolute value calculation units 9a, 9b in the comparison units 14a, 14b.
It is equivalent to comparing the output of b with the SI ₁ divided by 0.73. Therefore, to determine whether the SI value is equal to or greater than the predetermined value SI ₁ , the SI value is not obtained as a direct value, and the speed response output of the absolute value calculation units 9a and 9b is directly set to the set value SI ₁ /0.7.
It can also be done by comparing with 3.

Next, in the example of FIG. 7 (b), since the logical product section 17 which sets the output of the logical sum section 15 to 1 of the input signal uses the comparison result of the comparison section 14d as another input signal, the logical sum is calculated. The output of the section 15 becomes the output of the AND section 17 as it is only when the acceleration is a set value A ₂ or more smaller than the set value A ₁ and the holding section
The output is for control via 18. Note that reference numeral 19 indicates a return input line of the holding units 16 and 18 for performing the above-mentioned operation with respect to the signal every moment. In the example of FIG. 7 (b) described above, the shaded area in FIG. 8, that is, the area where the acceleration of the seismic motion is the set value A ₁ or more, and the acceleration of the seismic motion is the set value A ₁ or less and the set value A ₂ In the above range, the control output is issued in the region where the SI value (approximate value) is the set value SI ₁ or more. It should be noted that whether the boundary of the area belongs to inside or outside of the area is appropriate.
Further, the constituent elements in the above-mentioned configuration can be easily constituted by an appropriate electric circuit like the arithmetic unit 1, and in a microcomputer or the like if the arithmetic operation can be performed in real time or at a speed close to this. It can be easily implemented by software.

In the above embodiment, the acceleration signal is obtained from the common accelerometer 5 together with the SI value, but they may be independently configured depending on the case. Further, in the above embodiments, the SI value and the acceleration are simply associated with each other to obtain the control output, but they may be associated with an appropriate function. That is, the boundary of the region for issuing the control output may not be linear as shown in FIG. 8 but may be curved like an arc.

The above is a description of one system corresponding to one accelerometer 5, but the installation direction of the accelerometer 5, the number of installations, and the number of systems corresponding to each are appropriate. Each of them is installed so as to detect the acceleration of, and a control output is issued from each system,
It is also possible to determine these control outputs by an appropriate control device or the like and issue a higher control output.
As described above, in the present invention, the control output means not only a signal for directly controlling various systems but also a system of signals for controlling various systems by making higher-level judgment.

(Effects of the Invention) As described above, according to the present invention, the acceleration of seismic motion is input to the arithmetic unit that satisfies the equation of motion of the one-degree-of-freedom vibration system to obtain velocity response signals momentarily, and the velocity response signals are used to determine the structure during an earthquake. Since the SI value as an index of the vibration energy of an object can be obtained by approximating it momentarily without the need for a large-scale device, by issuing a control output based on this SI value or speed response and maximum acceleration. Therefore, it is possible to perform control that is highly correlated with the degree of damage to the structure.

For this reason, in the case of an earthquake with a large SI value, the control signal can be reliably emitted to control the system, because the maximum acceleration is relatively small and the conventional seismograph cannot emit a control signal. However, it is not possible to detect it with a control system, but the above-mentioned safety measures can be taken in the event of an earthquake that is likely to damage the structure. Therefore, it is possible to effectively prevent the expansion of damage and the occurrence of secondary disasters. The conventional maximum acceleration detection type seismometer, which can be configured as a seismograph, generates a control output even if it has an acceleration within the range of acceleration, if the SI value is small as in the case of a tenacious structure, a control output is generated. Therefore, it is possible to prevent unnecessary control of the system, and thus it is possible to prevent a large loss due to unnecessary control.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the relationship between the SI value and acceleration in a past earthquake and earthquake damage, FIGS. 2 (a) and 2 (b) are system explanatory diagrams of the embodiment of the calculation unit, and FIG. 3 is Fig. 4 is an explanatory diagram of the system configuration that can be considered when obtaining the SI value according to the definition formula.
A system explanatory view of an embodiment when the SI value is obtained by applying the method of the first invention, FIG. 5 is an explanatory view showing a concept of simplification of a velocity response spectrum in the method of FIG. 4, and Figures (a) and (b) are SI of the method of Figure 4 in past earthquakes.
Value (approximate value) and SI value (strict value) comparison explanatory diagram, FIGS. 7 (a) and 7 (b) are overall system explanatory diagrams of a concrete example for carrying out the method of the present invention, and FIG. 8 is FIG. It is explanatory drawing which shows the control output area | region in the structure of (b). Numeral 1 ... arithmetic unit, 2 ... addition unit, 3,4 ... integration unit, 5
...... Accelerometer, 6,6 ′ …… Reversing part, 7,8,7 ′, 8 ′, 13 ……
Multiplier, 9 (9a, 9b, 9c) ... Absolute value calculator, 10, 12 ...
Maximum value detector, 11 ... Average value calculator, 14 (14a, 14b, 14
c) …… Comparison section, 15 …… OR section, 16,18 …… Holding section, 17
…… Intersection section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoto Oho 1-170 Yayoi-cho, Chiba City Todai Nishi Chiba Staff 1-202 (72) Inventor Tadashi Saito 2-47-20-104 Chiba City Mitsuwadai (56) References JP-A-56-46479 (JP, A) JP-A-56-4082 (JP, A)

Claims (8)

(57) [Claims] 1. A set of two arithmetic units that satisfy the equation of motion of a one-degree-of-freedom vibration system, use an acceleration of seismic motion as an input signal, and output a velocity response as an output signal. Is also 20% and the natural period is 1.5 seconds,
2.5 seconds, input the acceleration signal of the seismic motion from a common accelerometer to each calculation unit, and obtain the speed response of each calculation moment by moment, and set a constant 0.73 to the larger value of the speed responses of these calculation units. The SI value of the vibration energy index of the structure at the time of an earthquake is approximated by the multiplied value, the SI value and the acceleration are compared with the respective set values, and control is performed when at least one side is equal to or more than the respective predetermined value. Seismic intensity detection method for control characterized by emitting a signal 2. An arithmetic unit is provided with a first and a second integrator in sequence on the output side of an adder for arithmetically operating the sum of a plurality of input signals, and the output of the first integrator has a natural angular vibration. A signal obtained by multiplying twice the product of the number and the damping constant, a signal obtained by multiplying the output of the second integrator by the square of the natural angular frequency, and an acceleration signal of seismic motion by an accelerometer are input to the adder. The control signal according to claim 1, wherein the signal is configured to satisfy the equation of motion of the vibration system with one degree of freedom, and the output signal of the first integrator is a velocity response signal. Seismic intensity detection method 3. A set of two arithmetic units that satisfy the equation of motion of a one-degree-of-freedom vibration system, use an acceleration of seismic motion as an input signal and output a velocity response as an output signal, and each of the arithmetic units has a damping constant. Is also 20% and the natural period is 1.5 seconds,
The acceleration signal of the seismic motion from a common accelerometer is input to each calculation unit for 2.5 seconds, and the speed response of each calculation unit is obtained moment by moment.The speed response with the larger value among these speed responses is calculated. , The velocity response corresponding to the SI value of the index of the vibration energy of the structure at the time of an earthquake is compared, and this velocity response and the acceleration are compared with the respective set values, and at least one side is equal to or more than the respective predetermined value. Method of detecting seismic intensity for control characterized by issuing control signal 4. The arithmetic unit sequentially provides first and second integrators on the output side of an adder that calculates the sum of a plurality of input signals, and the output of the first integrator has a natural angular vibration. A signal obtained by multiplying twice the product of the number and the damping constant, a signal obtained by multiplying the output of the second integrator by the square of the natural angular frequency, and an acceleration signal of seismic motion by an accelerometer are input to the adder. 4. The control according to claim 3, wherein the signal is configured to satisfy the equation of motion of the vibration system with one degree of freedom, and the output signal of the first integrator is a velocity response signal. Seismic intensity detection method 5. A calculation unit that satisfies the equation of motion of a one-degree-of-freedom vibration system and that uses an acceleration of seismic motion as an input signal and a velocity response as an output signal, and that calculates the damping constant
The natural period is set to 20% and the natural period is made to correspond to the portion where the shape of the velocity response spectrum is flat, and the acceleration signal of the seismic motion from the accelerometer is input to the above calculation unit to obtain the velocity response from moment to moment.
A value obtained by multiplying the velocity response by a constant 0.73 approximates the SI value of the index of the vibration energy of the structure at the time of an earthquake, compares the SI value and the acceleration with the respective set values, and at least one side sets the predetermined value. Method for detecting seismic intensity for control, characterized in that a control signal is issued when the value is greater than or equal to 6. An arithmetic unit is provided with first and second integrators sequentially on the output side of an adder for arithmetically operating the sum of a plurality of input signals, and the output of the first integrator has a natural angular vibration. A signal obtained by multiplying twice the product of the number and the damping constant, a signal obtained by multiplying the output of the second integrator by the square of the natural angular frequency, and an acceleration signal of seismic motion by an accelerometer are input to the adder. 6. The control according to claim 5, wherein the signal is configured to satisfy the equation of motion of the vibration system with one degree of freedom, and the output signal of the first integrator is a velocity response signal. Seismic intensity detection method 7. A calculation unit that satisfies the equation of motion of a one-degree-of-freedom vibration system and that uses an acceleration of seismic motion as an input signal and a velocity response as an output signal, and that calculates the damping constant
The natural period is set to 20% and the natural period is made to correspond to the portion where the shape of the velocity response spectrum is flat, and the acceleration signal of the seismic motion from the accelerometer is input to the above calculation unit to obtain the velocity response from moment to moment.
Comparing this speed response and the acceleration to each set value,
A method for detecting seismic intensity for control, characterized in that at least one side issues a control signal when the respective values are equal to or more than respective predetermined values. 8. An arithmetic unit is provided with first and second integrators on the output side of an adder for arithmetically operating the sum of a plurality of input signals, and the output of the first integrator has a natural angular vibration. A signal obtained by multiplying twice the product of the number and the damping constant, a signal obtained by multiplying the output of the second integrator by the square of the natural angular frequency, and an acceleration signal of seismic motion by an accelerometer are input to the adder. The control signal according to claim 7, wherein the signal is configured to satisfy the equation of motion of the one-degree-of-freedom vibration system, and the output signal of the first integrator is a velocity response signal. Seismic intensity detection method