JP3199148B2 - Seismic intensity measurement method for control - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a seismic intensity used for a control seismometer or the like.

[0002]

2. Description of the Related Art In the event of an earthquake, there is a control seismometer as a device for controlling various systems according to the intensity of the earthquake to prevent the spread of damage and the occurrence of secondary disasters.
2. Description of the Related Art Control seismometers have been incorporated in various facilities such as transportation, city gas, electric power, and water as an automatic emergency stop device at the time of a large earthquake.

In such a control seismometer, in order to perform a control having a high correlation with the degree of damage to a structure, for example, as shown in Japanese Patent Publication No. 4-35035, the SI value is measured as a measure of the intensity of earthquake motion. A measurement method has been proposed and implemented. In this method of measuring the intensity of seismic motion, the acceleration of the seismic motion is input to an arithmetic unit that satisfies the equation of motion of the one-degree-of-freedom vibration system, and the speed response is obtained every moment. Is used to calculate the SI value as the intensity of. Specifically, in this method, the calculation unit sets the attenuation constant to 20
% And the natural period are set to 1.5 seconds and 2.5 seconds, respectively, to form two sets, and the maximum value of the speed response of each natural period, which is the output of these arithmetic units, is set to the larger one. Constant 0.7
The SI value is approximately obtained by multiplying by 3.

[0004] This SI value is the natural period of the velocity response spectrum of a one-degree-of-freedom vibration system having a damping constant of 20% from 0.1 second to 2.5 seconds.
It is defined by the average value of the response speed in the range up to seconds, and if this SI value is calculated by the defined formula based on the acceleration obtained by the seismometer, a great deal of calculation is required. Is not practical. Therefore, in the method of the above document, the flat portion of the natural cycle of the velocity response spectrum of 1.5 to 2.5 seconds is represented by a value of the natural cycle of 1.5 seconds or 2.5 seconds, so that the value of 0.1 is obtained. The velocity response spectrum in the range from second to 2.5 seconds is approximated by a bent line that is bent at a point of a natural period of 1.5 seconds, an average value thereof is obtained, and this is estimated as the SI value.

[0005]

Therefore, the present inventors have made a large number of correlations between the SI value obtained by the above-described method, that is, the estimated SI value, and the SI value obtained by the definition formula, that is, the true SI value. As a result of a thorough investigation of the earthquake records, the estimated SI value obtained by the method of the above-mentioned document, which changes the natural period of interest in approximation of the velocity response spectrum of the ground motion when obtaining the SI value according to the magnitude of each velocity response Does not include systematic errors, and from this viewpoint it is found that the accuracy is good, and from the possibility that the change of the natural period affects the value variation, the possibility of improvement regarding the value variation is Was obtained. The present invention has been made in view of such a point, and an object of the present invention is to provide a high-precision seismic intensity measurement method for control with a small degree of variation and high accuracy compared to the conventional method described above. It is.

[0006]

In order to solve the above-mentioned problems, according to the present invention, an acceleration of a seismic motion is inputted, and an operation is performed which satisfies a set damping constant and a motion equation of a one-degree-of-freedom vibration system at a natural period. In the method of calculating the speed response every moment, and substituting the maximum value into a preset estimation formula to obtain the estimated SI value, the natural period to be set is 0.1 to 2.
3-5 points up to 5 seconds are selected, and the estimation equation is based on the equation of velocity response in the section of natural period 0.1-2.5 seconds by approximating the velocity response spectrum with a broken line connecting the values of these points. We propose a method of measuring seismic intensity for control using the formula to obtain.

In the present invention, in the above configuration, at least 1.5 seconds and 2.5 seconds are selected as the natural period. When the number of the selected natural periods is three, 1.
It is proposed that three points are obtained by adding one point of 1.5 seconds or less to two points of 5 seconds and 2.5 seconds.

[0008]

In the approximation of the velocity response spectrum of seismic motion when calculating the SI value, the degree of variation of the estimated SI value obtained without changing the predetermined natural period is determined even when the set natural period is one point. , Is smaller than the degree of variation of the estimated SI value obtained by the method of the above-mentioned document. However, when the number of set natural periods is two or less, S
The I value has a systematic error that cannot be ignored, and this systematic error can be made negligible by setting the number of the set natural periods to three or more.

When the number of the set natural periods exceeds three,
At five points, the correlation with the SI value becomes very high, and the degree of variation becomes very small. Therefore, even if the number of set natural periods is further increased, a significant improvement in the degree of variation cannot be expected, and the time required for the operation gradually increases as the set number increases. Therefore, it is desirable to set the number of the natural periods to 3 to 5 points.

Considering that the flat part of the velocity response spectrum starts at or near 1.5 seconds and considering the definition of the SI value, the eigenperiods of 3 to 5 points to be set have at least 1.5 seconds and 2 seconds. It is desirable to select .5 seconds. When the number of the set natural periods is three, the accuracy can be improved by adding one point of 1.5 seconds or less to these 1.5 seconds and 2.5 seconds.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 conceptually shows the configuration of a control seismometer to which the present invention is applied. Reference numeral 1 denotes an accelerometer, 2 denotes an estimated SI value calculation unit, and 3 denotes a control unit. The estimated SI value calculation unit 2 inputs the acceleration of the seismic motion detected by the accelerometer 1 at every sampling time of, for example, about 1/100 second, and sets a predetermined damping constant and a motion of the one-degree-of-freedom vibration system at a natural period. Calculating the speed response momentarily for each sample by performing an operation that satisfies the equation, obtaining the maximum value of the speed response, and substituting this maximum value into an estimation formula described in detail below to obtain an estimated SI value. These processes can be realized by, for example, combining various computing elements such as various computing units and filters as disclosed in the above-mentioned documents in terms of hardware, or by using a device to which a microcomputer is applied. It can be realized by software. Further, the control unit 3 calculates the estimated SI
Based on the estimated SI value estimated by the value calculation unit 2, safety measures such as controlling various systems and automatically stopping operation in the event of an earthquake that is likely to damage the structure are taken, As a specific method of such control, an appropriate method such as performing control in consideration of the maximum acceleration in addition to the estimated SI value can be applied as described in the above document.

Next, the SI value estimation formula set in the estimated SI value calculation unit 2 in the present invention will be described below together with the SI value definition formula and the SI value estimation formula according to the above document. First, as described above, the SI value is a natural period of 0.1 second to 2.5 seconds of the velocity response spectrum SV of the one-degree-of-freedom vibration system having a damping constant of 20%.
It is defined as the average response speed in the range up to seconds,
It is expressed as the following equation.

(Equation 1)

On the other hand, the method of estimating the SI value shown in the above-mentioned literature, that is, with a damping constant of 20%, a natural period of 1.5 seconds, and 2.
In the method of estimating the SI value by multiplying the larger one of the maximum values of the velocity response of the 5-second one-degree-of-freedom vibration system by a constant, the estimation equation of the estimated SI value can be expressed as the following equation. it can. SI _k (20) = max [SV (2.5), SV (1.5)] × 1.7 / 2.4 Here, SV (1.5) and SV (2.5) are the maximum values of the speed response at the natural periods of 1.5 seconds and 2.5 seconds, respectively. And max [a.
b] is an operator for adopting the larger value of a or b, and “20” of SI _k (20) emphasizes that 20% is adopted as a damping constant. The same applies to expressions.

Next, in the present invention, the estimating equation set in the estimated SI value calculating section 2 selects 3 to 5 points whose natural period is in a section of 0.1 to 2.5 seconds, and converts the speed response spectrum into these. Eigen period of 0.1 to approx.
The average of the speed response in the section of 2.5 seconds is obtained.
This is expressed as the following general formula.

(Equation 2) As shown in the conceptual diagram of FIG. 2, the above equation approximates the section of the natural period of the speed response spectrum of 0.1 to 2.5 seconds by a broken line connecting the values of the points of a plurality of natural periods selected and set. Is a general expression for calculating the speed response in this section, and T _{j + 1}
Is 2.5 seconds.

When the natural period set in the above equation is two points, for example, two points of 1.5 seconds and 2.5 seconds, the equation is: SI ₂ (20) = [SV (1.5) × 0.7 + {SV (1.5) + SV (2.5)} ×
0.5] /2.4. In addition, an equation in a case where the set natural period is only one point, for example, only 1.5 seconds, is expressed as SI ₁ (20) = SV (1.5) × 1.7 / 2.4.

The results of obtaining the estimated SI value represented by the above equation and the SI value of the definition equation for a large number of earthquake records are shown below. The earthquake records are based on the records used in the "Research Report on Information for Judgment of Emergency Measures in the Event of an Earthquake" (April 1991, Japan Gas Association). Forty earthquake records observed in a famous earthquake are used.

First, FIGS. 3 to 5 show that SI _k (20), SI ₁ (20), and SI ₂ (20) obtained from the above-mentioned earthquake records are respectively converted into SI values (hereinafter simply referred to as SI or (Expressed as SI value). In these figures, the horizontal axis represents the SI value.
When there is a linear relationship between the value and the linear relationship, particularly the gradient 1, the estimation accuracy is good and there is no systematic error. From FIG. 3, although SI _k (20) has relatively large variation,
When the relationship between SI approximated by the average linear, the slope of the line L _k is approximately 1, and it can be seen that does not contain systematic errors. Incidentally, since, in a linear gradient 1 are shown as L _0. Next, from FIGS. 4 and 5, SI ₁ (20) and SI ₂ (20) have a linear relationship with SI, but the gradients of the straight lines L ₁ and L ₂ are different from 1, and therefore, systematic. It can be seen that an error is included.
Therefore, these values cannot be directly used as the estimated SI values. However, it can be seen that the value variation is smaller than SI _k (20).

Then, next, according to the present invention, SI _i (20) (i ≧
Embodiment 3) will be described with reference to FIGS. FIG. 6 shows SI ₃ (20) (setting natural period T (second): 1.0, 1.5, 2.5)
3 shows the relationship between SI and SI. Figure 7 shows SI ₃ (20)
It shows the relationship between (set natural period T (second): 0.7, 1.5, 2.5) and SI. FIG. 8 shows the relationship between SI ₄ (20) (set natural period T (second): 0.44, 0.8, 1.5, 2.5) and SI. FIG. 9 shows SI ₅ (20) (setting natural period T (second):
0.44, 0.8, 1.5, 2.0, 2.5) and the SI. Note that the straight lines L ₃ , L ₄ , and L ₅ shown in each figure are straight lines that approximate the relationship with the SI similarly to the above.

As can be seen by comparing FIGS. 5 and 6, the speed response spectrum is approximated by a broken line connecting two values of the natural period of 1.5 seconds and 2.5 seconds. In the case where the value of the point at 1 second is added to the value of the point and the value is approximated by a broken line connecting these values, the variation becomes smaller, the correlation with SI becomes higher, and the systematic error becomes very small. ing. Therefore, the latter according to the present invention can estimate the SI value with higher accuracy than the former.

As can be seen by comparing FIGS. 6 and 7,
Similarly, when the number of the set natural periods is three, and two of them are also 1.5 seconds and 2.5 seconds, another natural period is set from the former one second to the latter one. 0.7
The variation is further reduced by changing to seconds. Therefore, the estimation accuracy of the SI value is further improved. By appropriately selecting the natural period of 1.5 seconds or less in this way, it is possible to improve the estimation accuracy of the SI value.

As can be seen by comparing the above figures with FIGS. 8 and 9, respectively, the number of set natural periods is four,
Then, the variation is further reduced, and the correlation with SI becomes extremely high. Therefore, even if the set number of the natural periods is further increased, it is not possible to expect a significant improvement in the estimation accuracy of the SI value enough to offset the disadvantage that the calculation time in the estimated SI value calculation unit 2 becomes long. This is not a good idea.

When three or more natural periods are set, each natural period can be set to an appropriate point from 0.1 to 2.5 seconds. Starting at or near 1.5 seconds;
Considering the definition formula of the SI value, it is desirable that the plurality of eigencycles to be set include 1.5 seconds and 2.5 seconds.
In addition, other natural periods, particularly at 1.5 seconds or less, a point on the longer side than the vicinity of 0.1 second where the SV value is small, for example, the above-described natural periods such as 0.44 seconds, 0.7 seconds, and 1 second. It is preferred to select

Table 1 shows the degree of variation in the estimated SI value in each of the above embodiments. FIG. 10 shows the relationship between the degree of variation of the estimated SI value and the set number of natural periods. However, in Table 1 and FIG. 10, the degree of variation is not the standard deviation σ, but a value obtained by dividing the estimated standard deviation σ of the variation by the average SI value (μ = 38 cm / sec) of the above 40 earthquake records. , Ie, the variation coefficient (σ / μ). FIG.
At 0, x indicates the variation coefficient, and □ indicates the variation coefficient of the estimated SI value according to the above document.

[Table 1]

The following is clear from Table 1 and FIG. The coefficient of variation of the estimated SI value according to the method described in the above-mentioned document is larger than that in the case where the set number of natural periods is two. The variation coefficient when the set number of the natural periods is three is significantly lower than that when the number is two. When the set number of the natural periods is three or more, the coefficient of variation decreases as the number of points increases, but the rate of the decrease is small.

From the above, it is preferable that the number of the natural periods set in the estimation of the SI value is 3 to 5 points, and it is better to set appropriately within this range in consideration of the calculation time. For example, it is best to select three points when the time required for the operation is to be shortened, and when there is sufficient spare capacity in the operation performance, it is possible to further improve the accuracy by increasing the number of points. it can.

[0026]

Since the present invention is as described above, the method of the above-mentioned document for selecting the larger value of the maximum value of the speed response of the natural period of 1.5 seconds or 2.5 seconds to obtain the estimated SI value is described. The variance of estimated SI value and systematic error are very small as compared with, and therefore, the intensity of seismic wave applied to the seismometer for control to prevent the spread of damage and the occurrence of secondary disaster in the event of an earthquake is small. Measurement can be performed with high accuracy by calculation.

[Brief description of the drawings]

FIG. 1 is a system diagram conceptually showing a configuration of a control seismometer to which a method of the present invention is applied.

FIG. 2 is an explanatory diagram showing an approximation method of a velocity response spectrum in the method of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between SI _k (20) and SI.

FIG. 4 is an explanatory diagram showing a relationship between SI ₁ (20) and SI.

FIG. 5 is an explanatory diagram showing a relationship between SI ₂ (20) and SI.

FIG. 6 is an explanatory diagram showing a relationship between SI ₃ (20) and SI.

FIG. 7 shows S having a different natural period from SI ₃ (20) in FIG.
FIG. 4 is an explanatory diagram showing a relationship between I ₃ (20) and SI.

FIG. 8 is an explanatory diagram showing a relationship between SI ₄ (20) and SI.

FIG. 9 is an explanatory diagram showing a relationship between SI ₅ (20) and SI.

FIG. 10 is an explanatory diagram showing a relationship between a degree of variation of an estimated SI value and a set number of natural periods.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Accelerometer 2 Estimated SI value calculation part 3 Control part

Claims (3)

(57) [Claims] 1. An acceleration equation of a seismic motion is input, and a speed response is obtained from time to time by performing an operation that satisfies a set damping constant and a motion equation of a one-degree-of-freedom vibration system at a natural period, and a maximum value thereof is an estimation formula set in advance. In the method of obtaining the estimated SI value by substituting the values into 3 to 5, the eigen period to be set is selected from 3 to 5 points from 0.1 to 2.5 seconds, and the estimation equation calculates the velocity response spectrum by calculating the value of each point. A seismic intensity measuring method for control, characterized by formulating an average of speed response in a section of a natural period of 0.1 to 2.5 seconds by approximating by a connecting broken line. 2. The natural period is at least 1.5 seconds and 2.
2. The method according to claim 1, wherein 5 seconds is selected. 3. The control system according to claim 2, wherein the natural period is three points obtained by adding one point of 1.5 seconds or less to two points of 1.5 seconds and 2.5 seconds. Earthquake Ground Motion Measurement Method