JPH0435035B2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention controls various systems and automatically operates them in order to prevent the spread of damage and the occurrence of secondary disasters in the event of a major earthquake. Applicable to control seismographs for taking safety measures such as stopping
This invention relates to a seismic motion intensity detection method for control purposes.

(Conventional technology and issues) Currently, control seismographs are used for transportation, city gas,
They are incorporated as automatic emergency stop devices in the event of a major earthquake, from various industrial facilities such as electric power and water supply facilities to household appliances such as kerosene stoves, and there are a wide variety of devices ranging from extremely high-precision ones to simple ones. However, most of these conventional control seismometers belong to the maximum acceleration detection type.

However, in the case of an earthquake, the maximum acceleration of seismic motion does not necessarily correspond to the damage to the facilities to be controlled, and even if the maximum acceleration is large, the damage to the facilities may be minor, as described below. This has been confirmed through earthquake observations and vibration experiments.
Therefore, if control is attempted only by detecting the maximum acceleration, the seismograph will issue control signals and control the facility, such as stopping its functions, even if the earthquake causes no or very minor damage to the facility. As the system ages, it becomes difficult to recover from this state.
Unnecessary control can lead to significant losses. Therefore, there has been a desire for a highly reliable control seismograph that can perform control according to the degree of damage.

The conventional control seismograph mentioned above detects the acceleration of earthquake motion, assuming that the force applied to the structures of various facilities due to earthquake motion is the cause of destruction, but structures are not necessarily destroyed by force. Not only that, but in the case of strong structures, the vibration energy of the structure during an earthquake contributes to its destruction. For example, in 1961, GW Hausner announced the concept of SI value as a measure of the strength of an earthquake, arguing that it is the vibration energy of a structure during an earthquake that contributes to its ultimate failure. This SI
The value is defined as the average value of the response speed in the natural period range of 0.1 seconds to 2.5 seconds of the speed response spectrum of a one-degree-of-freedom vibration system with a damping constant of 20%, and is the speed response of the actual seismic waveform record. It has been reported that the relationship between SI values obtained by analyzing spectra and seismic intensity is better than that between acceleration and seismic intensity.

Figure 1 shows the results of the inventors' calculation of the SI values for a large number of strong earthquake records in both Japan and the United States, and the investigation of the relationship between this SI value, acceleration, and earthquake damage. occurs when the SI value exceeds approximately 25cm/s, and when the SI value is smaller than this value, there are many cases where no damage occurs even when the acceleration is large.
It can be seen that there is a high correlation between SI value and damage. This also shows that conventional control seismometers, which attempt to control only by detecting the maximum acceleration, can control even earthquakes that cause no damage, as mentioned above. In addition, in the event of an earthquake where the acceleration is smaller than the maximum acceleration that should be detected by a seismograph, but the SI value is large and there is a high possibility of damage to structures, conventional seismographs can detect the necessary stability as described above. Unable to take action.

The present invention was created in view of the above points,
In other words, by detecting the intensity of earthquake motion not only as the maximum acceleration corresponding to the force applied to the structure, but also as the above-mentioned SI value corresponding to the vibration energy of the structure, it is possible to perform control that is more responsive to the degree of damage. The purpose is to make it possible to construct a highly reliable control seismograph.

By the way, the SI value is given by the above definition, so if you try to calculate it based on the acceleration obtained by a seismograph, you will need a very large-scale device as described later. .

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

(Means for Solving the Problems) To explain the means for solving the above-mentioned problems, first, the seismic motion intensity detection method for control according to the first invention satisfies the equation of motion of a one-degree-of-freedom vibration system and detects seismic motions. There are two sets of calculation units that use acceleration as an input signal and speed response as an output signal, and each calculation unit has a damping constant of 20% and a natural period of 1.5 seconds and 2.5 seconds, respectively. The gist is to input the acceleration signal of earthquake motion from a common accelerometer to each calculation unit, calculate each velocity response moment by moment, and obtain an approximate value of the SI value by multiplying the larger velocity response by a constant 0.73. shall be.

In addition, the seismic motion intensity detection method for control according to the second invention includes a calculation unit that satisfies the equation of motion of a one-degree-of-freedom vibration system, uses the acceleration of the seismic motion as an input signal, and uses the velocity response as an output signal; The calculation section is
The damping constant is set to 20%, the natural period is made to correspond to the flat part of the velocity response spectrum, and the acceleration signal of the seismic motion from the accelerometer is input to the above calculation unit to obtain the velocity response moment by moment. The gist is to obtain an approximate value of the SI value by multiplying by a constant 0.73.

(Effect) In general, the natural periodic characteristic of the velocity response spectrum of seismic waves changes upward in the short period, but becomes almost flat in the long period, so if this characteristic is used, calculations can be made according to the above definition. At the very least, the SI value can be easily approximated and obtained.

In other words, the acceleration signal of earthquake motion from a common accelerometer is set with a damping constant of 20% and a natural period of 1.5 seconds.
Input to each of the two sets of calculation sections for 2.5 seconds,
Each velocity response is determined moment by moment, and the larger velocity response is multiplied by a constant of 0.73, or the acceleration signal of the seismic motion from the accelerometer is set to correspond to a flat part of the velocity response spectrum, such as with a natural period of 2.5 seconds. input into one set of calculation units, and the constant 0.73 is applied to the speed response.
By multiplying by

(Examples) Next, the present invention will be described in detail with reference to Examples.

First, FIG. 2 is a system explanatory diagram of an embodiment of the arithmetic unit 1 used in the method of the present invention. This calculation unit 1 calculates the equation of motion of a one-degree-of-freedom vibration meter, namely x¨+2whx〓+w ² x=-Z¨...(1) x: Displacement of the mass of the building with respect to the ground Z: Coordinate fixed in space Displacement of the ground against Configure it to be a signal. To specifically explain the configuration of FIGS. 2a and 2b, this calculation section 1 sequentially connects one input signal to the output side of an addition section 2 that calculates the sum of a plurality of input signals.
In addition, second integration sections 3 and 4 are provided, and a signal 2whx, which is obtained by multiplying the output x of the first integration section 3 by twice the product of the natural angular frequency w and the damping constant h, and a second integration section 3 and 4 are provided. Integral section 4
The signal W ² is the output x multiplied by the square of the natural angular frequency.
x and the acceleration signal Z of the earthquake motion from the accelerometer 5 as input signals of the adder 2, and these input signals are inverted before being input to the adder 2 as shown in FIG. 2a, or As shown in FIG. 2b, the configuration is such that the sum signal is inverted on the output side of the adder 2, satisfying the equation of motion of the one-degree-of-freedom vibration system, and the output signal of the first integrating unit 3 is inverted as a sum signal. This is a speed response signal. In FIG. 2a, 6 is the inverted part of the acceleration signal Z of the seismic motion by the accelerometer 5, 7 is the output X of the first integrating part 3,
A multiplier section 8 multiplies the product of the natural angular frequency w and the damping constant h by twice, and inverts this to generate a signal -2whx. This is a multiplier that multiplies the square and inverts it to generate a signal -w ² x. If the output signal of the first integrating section 3 is the speed response signal
Since the input side signal of the integrating section 3 is expressed as x,
After all, on the input side of the first integrating section 3, the following equation x¨=-Z¨-2whx〓-w ² x...(2) is satisfied, and therefore, one degree of freedom expressed by the above equation (1) This satisfies the equation of motion of the vibration system. Also, the multipliers 7' and 8' in FIG. 2b, unlike the multipliers 7 and 8 in a, generate non-inverted signals 2whx and W ² The signal is then inverted by the inverting section 6', and the equation (2) is satisfied on the input side of the first integrating section 3, similar to the configuration shown in FIG. 2a. The configuration of Figure 2 a and b is as described above.
(2) is literally satisfied, but since it is sufficient to obtain the absolute value of the speed response, the output signal of the first integrating section 3 is configured to be −x〓. The acceleration signal of the seismic motion can also be positive in either direction, so Figure 2a
It is also possible to omit the inverter 6 for the acceleration signal of earthquake motion shown in FIG. The components such as the adder 1 in the above configuration can be easily implemented using appropriate electric circuits, or can be implemented using software in a microcomputer etc. if the calculations can be performed in real time or at a speed close to this. It is also possible to implement components such as those described above. The natural angular frequency and damping constant can also be easily set by changing the values of the circuit elements or by changing the constants on the software. In this way, the calculation unit 1 may have any configuration as long as it can obtain the velocity response signal moment by moment 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.

By using a large number of the calculation units 1 described above, the SI value can be determined according to the above-mentioned set expression. That is, for example, as shown in Figure 3, the damping constant is set to 20%, and the natural period is set in small increments from 0.1 seconds to 2.5 seconds (for example, 1/100
A large number of calculation units 1 are configured (second by second), and each speed response signal from these calculation units 1 is sent to an average value calculation unit 11 via an absolute value calculation unit 9 and a maximum value detection unit 10. The SI value can be calculated by inputting the information. However, this method has the disadvantage of requiring large-scale equipment, and is not practical.

Therefore, in the first invention, the characteristics of seismic waves are utilized; in other words, the natural periodic characteristics of the velocity response spectrum of seismic waves generally change upward to the right in short periods, but become almost flat in long periods; Utilizing such characteristics, the SI value is easily approximated and determined as follows.

That is, in the first invention, as shown in FIG. 4, the calculation section 1 has a damping constant of 20% and a natural period of 1.5.
The approximate value of the SI value is calculated by multiplying the larger of the maximum values of the speed responses to the calculation unit 1 by a constant.

In other words, the maximum value of the velocity response of a one-degree-of-freedom vibration system due to earthquake motion is a function of the natural period, as mentioned above, and has an upward-sloping shape, but when this natural period is several seconds or more, it tends to show an almost constant value. The first invention utilizes this tendency to obtain the SI value with sufficient accuracy for practical use by a speed response with a small natural period. That is, in the first invention, the shape of the speed response spectrum is simplified as shown in FIG. Take the value and approximate it using the following formula.

SI value (approximate value) = 1.75/2.4 (the larger value of the maximum value of the speed response with a natural period of 1.5 seconds or 2.5 seconds)...(3) That is, since 1.75/2.4 = 0.73, the larger value above Multiply the velocity response by a constant 0.73 to approximate the SI value.

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

FIG. 4 systematically shows an example of a configuration for carrying out the method for calculating the SI value (approximate value) described above, in which reference numeral 12 is a maximum value detection section, and 13 is a multiplication section for the above-mentioned constant.

As described above, the first invention includes two sets of arithmetic units 1
This is a method of approximating the SI value by a and 1b,
The second invention provides a set of arithmetic units 1 as shown below.
An approximate value of the SI value is obtained by

The configuration for this is, for example, from the configuration shown in FIG.
The calculation unit 1a and the absolute value calculation unit 9a can be deleted and the SI value can be approximated by the following equation using a velocity response with a natural period of 2.5 seconds. Of course, the natural period used for the approximation is not 2.5 seconds as described above, but any appropriate natural period of a portion where the shape of the velocity response spectrum is flat can be used.

Figure 6b shows a comparison between the approximate value obtained using this method and the strictly calculated SI value.As can be seen from this figure, the correlation between the two is slightly lower than that in Figure 6a, but it is sufficient. Therefore, even with this method using one set of arithmetic units 1b, the SI value can be approximated with a practically sufficient accuracy using the speed response signal in the arithmetic unit 1b.

As described above, the present invention calculates the SI value as an index of the vibration energy of a structure during an earthquake.
Because it can be obtained moment by moment when an earthquake occurs,
By appropriately configuring to issue a control output based on such SI value, it is possible to perform control highly correlated with the degree of damage to the structure.

For example, the SI value obtained as described above is compared with a set value by an appropriate comparing section, and when the SI value is greater than or equal to this set value, a control output is generated. If this is the case, in the event of an earthquake that causes all of the damage shown in Figure 1, a control output will be generated to control various systems and automatically operate in order to prevent the spread of damage and the occurrence of secondary disasters. Safety measures such as stopping the vehicle can be taken.

Therefore, the maximum acceleration is relatively small (for example, about
250cm/s ² or less), therefore, although conventional maximum acceleration seismometers do not emit control signals, if the SI value is larger than the above set value, it is possible to emit a control signal and control the system as described above. A control system that allows the above-mentioned safety measures to be taken in the event of an earthquake that cannot be detected by conventional seismometers but is likely to cause damage to structures, thereby effectively preventing the spread of damage and the occurrence of secondary disasters. A seismometer can be constructed for

It goes without saying that the present invention may be configured to operate independently, but by incorporating the acceleration signal from the accelerometer and operating in combination, it is possible to more effectively reduce the earthquake motion intensity. can be detected. The configuration shown in FIG. 7 shows an embodiment thereof, in which a control signal is generated when either or both of the SI value and the acceleration signal are greater than a predetermined value. This will be explained in detail below.

In FIG. 7, reference numeral 5 indicates an accelerometer, 1a, 1
b is an arithmetic unit whose damping constant is set to 20% and whose natural period is set to 1.5 seconds and 2.5 seconds, respectively, and the output signals of these arithmetic units 1a and 1b are transmitted through absolute value arithmetic units 9a and 9b, respectively. The data is inputted to the comparison sections 14a and 14b, and compared with the same set value in these comparison sections 14a and 14b. Such setting value is SI value
It corresponds to SI ₁ . Then, the acceleration signal from the accelerometer 5 that does not pass through the calculation section 1 is inputted to the comparison section 14c via the absolute value calculation section 9c, and is compared with a set value corresponding to the value _A1 described below in the comparison section 14c. . The configuration of FIG. 7a is the comparison section 14a,
The comparison output signals of 14b and 14c are input to an OR section 15, and the output of this OR section 15 is controlled and output. In the configuration shown in FIG. 7b, the acceleration signal is input to another comparison section 14d, and this comparison section 14d compares it with a value _A2 smaller than the value _A1 . and the comparison section 14a,
The comparison output signals of 14b and 14c are sent to the logical sum section 1.
5, the comparison output of the comparison section 14d is passed through the holding section 16, and is used as an input signal of the ANDing section 17 together with the output of the ORing section 15. It is used as an output for control.

However, as mentioned above, the SI value (approximate value) of the index can be calculated by multiplying the larger of the maximum values of the speed response for natural periods of 1.5 seconds and 2.5 seconds by a constant. Judging whether or not the _magnitude of
This is equivalent to determining whether the magnitude of the momentary speed response signal of is equal to or greater than the value corresponding to the predetermined value SI ₁ , and therefore
14b, it can be determined whether the index SI value (approximate value) obtained from the acceleration of the actual seismic motion is greater than or equal to the predetermined value SI ₁ . That is, in the present invention, the SI value (including approximate values) may be obtained as a direct value, or may not be obtained as a direct value.
It may also be obtained indirectly through equivalent processing.

Next, in FIG. 7b, the AND section 17 which takes the output of the OR section 15 as 1 of the input signal is connected to the comparison section 14.
Since the comparison result of b is used as another input signal, the output of the logical sum section 15 becomes the output of the logical product section 17 only when the acceleration is greater than or equal to the value _A2 , which is smaller than the value _A1 . It is outputted for control via the holding section 18, and reference numeral 19 indicates a return input line of the holding sections 16 and 18 for performing the above operation on the momentary signals. The embodiment shown in FIG _{. 7b} has _the SI value ( Approximate value) is a control output in a region where the value SI is ₁ or more. Note that it is appropriate to determine whether the boundary of the area belongs to the inside or outside of the area. In addition, the components in the above configuration can be easily configured with appropriate electric circuits like the calculation unit 1, and if the calculations can be performed in real time or at a speed close to this, software in a microcomputer or the like can be used. It can be easily configured.

In the configuration of the above embodiment, the acceleration value A ₁
is set to be larger than the acceleration (e.g., approximately 250 cm/s ² ) at which a conventional maximum acceleration detection seismometer emits a control output, for example, 400 cm/s ² , which corresponds to a severe earthquake.
Furthermore, if the SI value SI ₁ is set to, for example, the aforementioned 25 cm/s, if an earthquake occurs, not only will the SI value be a large value (value SI ₁ or more...25 cm/s or more), but the maximum acceleration will be Even if the value is extremely large (value A ₁ or more...for example, corresponding to 400 cm/s ² or more, which corresponds to the aforementioned severe earthquake), a control signal is issued, and various measures are taken to prevent the spread of damage and the occurrence of secondary disasters. It is possible to take safety measures such as controlling the system to automatically stop operation. That is, in this embodiment, even if the acceleration of the actual seismic motion is a certain value, for example, the value at which the conventional maximum acceleration type seismometer described above issues a control signal (for example, about 250 cm/s ² ), the predetermined value If A is less than ₁ , the control signal is not issued based on this acceleration value alone, and the control signal is issued only when the index satisfies the condition that the predetermined value SI is greater than or equal to ₁ , so the maximum acceleration is relatively large. However, in earthquakes where the index is small (of course, the value A is less than ₁ ) (value SI is less than ₁ ), that is, in the case of strong structures, there is no damage or very slight damage, the control of the system is not necessary. Since it is possible to avoid performing such unnecessary control, it is possible to prevent a large amount of loss caused by such unnecessary control. In the embodiments described above, the acceleration signal and the SI value are obtained from the common accelerometer 5, but these may be configured independently depending on the case. Furthermore, in the above embodiments, the control output is obtained by simply relating the acceleration of the actual seismic motion using a logical sum, but it is also possible to make the relation using any of these appropriate functions, that is, to generate the control output. The boundaries of the regions are not linear as shown in FIG. 8, but may be curved, such as arcuate.

The above is an explanation of one system corresponding to one accelerometer 5, but the installation direction of accelerometers 5, the number of installations, and the number of systems corresponding to each may be determined as appropriate.
For example, accelerometers are installed to detect acceleration in two horizontal directions and in the vertical direction, and a signal current is generated to obtain the above SI value from each system, and these indicators are combined and set in an appropriate control device, etc. The above-mentioned control can be performed based on the judgment.

(Effects of the Invention) As described above, the present invention inputs the acceleration of earthquake motion into a calculation unit that satisfies the equation of motion of a one-degree-of-freedom vibration system, obtains velocity response signals from time to time, and uses these velocity response signals to determine when an earthquake occurs. Approximate values of the SI value, which is an index of the vibration energy of a structure, can be obtained from time to time without the need for large-scale equipment, so by configuring the system to issue a control output based on this SI value, Control that is highly correlated with the degree of damage to structures can be performed.

By performing such control, although conventional seismometers cannot issue control signals because the maximum acceleration is relatively small, in the case of an earthquake with a large SI value, it is possible to reliably issue control signals and control the system. Although conventional seismometers cannot detect it, the safety measures mentioned above can be taken in the event of an earthquake that is likely to cause damage to structures, effectively preventing the spread of damage and the occurrence of secondary disasters. This has the effect that it is possible to configure a control seismograph that can be controlled.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the relationship between SI values and acceleration and earthquake damage in past earthquakes, Figure 2 a, b
3 is an explanatory diagram of the system of the embodiment of the calculation section, FIG. 3 is an explanatory diagram of the system when the SI value is determined according to the defining formula, and FIG. 4 is an explanatory diagram of the system when the SI value is determined by applying the method of the first invention. An explanatory diagram of the system of the example, Fig. 5 is an explanatory diagram of the simplification of the velocity response spectrum in the method of Fig. 4, and Fig. 6 a and b are diagrams of the method of Fig. 4 in past earthquakes.
A comparison explanatory diagram of SI value (approximate value) and SI value (exact value), Figures 7a and b are diagrams explanatory of the overall system of the embodiment of the method of the present invention, and Figure 8 is a diagram showing the configuration of Figure 7b. FIG. Code 1...Arithmetic section, 2...Addition section, 3, 4...
Integral section, 5... accelerometer, 6, 6'... inversion section,
7, 8, 7', 8', 13...multiplication section, 9, 9a,
9b, 9c... Absolute value calculation section, 10, 12... Maximum value detection section, 11... Average value calculation section, 14, 14
a, 14b, 14c... Comparison section, 15... Logical sum section, 16, 18... Holding section, 17... Logical product section.

Claims (1)

[Scope of Claims] 1. Two sets of calculation units that satisfy the equation of motion of a one-degree-of-freedom vibration system and use the acceleration of earthquake motion as an input signal and the velocity response as an output signal are configured, and each calculation unit has a damping The constant is set to 20%, and the natural period is set to 1.5 seconds and 2.5 seconds, respectively, and the acceleration signal of the earthquake motion from a common accelerometer is input to each calculation unit, and the velocity response of each is calculated moment by moment, and the larger one is calculated. A control seismic motion intensity detection method characterized by obtaining an approximate value of the SI value by multiplying the velocity response of by a constant 0.73. 2. Constructs an arithmetic unit that satisfies the equation of motion of a one-degree-of-freedom vibration system, takes the acceleration of earthquake motion as an input signal, and takes the velocity response as an output signal, and this arithmetic unit:
The damping constant is set to 20%, the natural period is made to correspond to the flat part of the velocity response spectrum, and the acceleration signal of the seismic motion from the accelerometer is input to the above calculation unit to obtain the velocity response moment by moment. A control seismic motion intensity detection method characterized by obtaining an approximate value of the SI value by multiplying by a constant 0.73. 3. The arithmetic unit sequentially provides first and second integrating units on the output side of the adding unit that calculates the sum of a plurality of input signals, and applies the natural angular frequency and damping constant to the output of the first integrating unit. and a signal obtained by multiplying the output of the second integration section by the square of the natural angular frequency.
A configuration is adopted in which an acceleration signal of seismic motion from an accelerometer is used as an input signal of the addition section to satisfy the equation of motion of a vibration system with one degree of freedom, and an output signal of the first integration section is used as a velocity response signal. A seismic motion intensity detection method for control according to claim 1.