JPH0815442A - Measuring method of intensity of earthquake motion for control - Google Patents

Abstract

PURPOSE:To provide a measuring method of the intensity of an earthquake motion, in which the degree of dispersion is reduced and which has high accuracy, in a control seismograph, etc., using an SI value as the measure of the intensity of the earthquake motion. CONSTITUTION:The acceleration of an earthquake motion is input, arithmetic operation satisfying the equation of motion of one freedom-degree vibration system in a set attenuation constant and a natural period is conducted, and speed response is obtained momently. The maximum value of speed response is substituted for preset estimation formula, and an estimated SI value is acquired. The regression coefficient of a regression linear equation, using the estimated SI value as a dependent variable, and an SI value obtained from definition formula as an independent variable is acquired from the Si value obtained by the definition formula regarding a large number of earthquake records and the estimated SI value acquired by the estimation formula under the desired set conditions, and an estimated SI value obtained by inputting the acceleration of the earthquake motion as an object is corrected by correction formula employing the regression coefficient.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art When an earthquake occurs, there is a seismometer for control 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.
The seismograph for control is incorporated in various facilities such as transportation facilities, city gas, electric power, and water supply as an automatic emergency stop device at the time of a large earthquake.

In such a control seismometer, in order to perform control having a high correlation with the degree of damage to the structure, for example, as shown in Japanese Patent Publication No. 4-35035, SI value is used as a measure of the intensity of seismic motion. A method of measuring is proposed and implemented. This seismic-motion intensity measuring method inputs the acceleration of seismic motion into an arithmetic unit that satisfies the equation of motion of a one-degree-of-freedom vibration system to obtain the speed response from moment to moment, and from the spectrum of the maximum velocity response, that is, the velocity response spectrum SV The SI value as the intensity of is calculated. Specifically, in this method, the computing unit sets the damping constant to 20
%, The natural period is set to 1.5 seconds and 2.5 seconds, respectively, and two sets are configured, and the larger one of the maximum values of the speed response of each natural cycle which is the output of these calculation units is set to the larger speed response. Constant 0.7
The SI value is approximately obtained by multiplying by 3.

This SI value is a natural period of 0.1 second to 2.5 of the velocity response spectrum of a one-degree-of-freedom vibration system with a damping constant of 20%.
It is defined by the average value of the response speed in the range up to seconds, and if this SI value is calculated according to the definition formula based on the acceleration obtained by the seismograph, it requires a great deal of calculation. Becomes impractical. Therefore, in the method of the above-mentioned document, the flat portion of the natural period of 1.5 seconds to 2.5 seconds of the velocity response spectrum is represented by the value of the natural period of 1.5 seconds or 2.5 seconds to obtain 0.1. The velocity response spectrum in the range of seconds to 2.5 seconds is approximated by a polygonal line that bends at a point with a natural period of 1.5 seconds, the average value is obtained, and this is estimated as the SI value.

[0005]

Therefore, the present inventors have made many correlations between the SI value obtained by the above 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 diligent research on the seismic record, the estimated SI value obtained by the method of the above document in which the natural period of interest in the approximation of the velocity response spectrum of the ground motion when obtaining the SI value is changed according to the magnitude of each velocity response Does not include systematic errors, and from this point of view, we have obtained the knowledge that the accuracy is good, and there is a possibility that the variation in the value will be improved due to the possibility that the change in the natural period affects the variation in the value. I got the knowledge of. The present invention was devised in view of the above point, and it is an object of the present invention to provide a highly accurate seismic-motion intensity measuring method with a small degree of variation as compared with the above-described conventional method.

[0006]

In order to solve the above-mentioned problems, according to the present invention, the acceleration of seismic motion is input, and the calculation is performed to satisfy the set damping constant and the equation of motion of the one-degree-of-freedom vibration system in the natural period. In the method of obtaining the estimated SI value by substituting the maximum value into the preset estimation formula, the velocity response is calculated every moment, and the SI value obtained by the definition formula for a large number of earthquake records under the desired setting conditions and the above estimation formula. From the estimated SI value obtained by, the regression coefficient of the regression linear equation with the estimated SI value as the dependent variable and the SI value obtained from the definition formula as the independent variable is obtained, and the acceleration of the target earthquake motion is input and obtained. It is characterized in that the obtained estimated SI value is corrected by a correction formula using the above regression coefficient.

In the present invention, the damping constant in the above method is set to 20% as in the definition of SI value.
We suggest setting it to something other than 20%.

In the present invention, any one point from 1.5 seconds to 2.5 seconds is set as the natural period in the above method, and the flat portion of the velocity response spectrum is represented by the value of this point. The estimation formula is a formula for approximating the velocity response spectrum by a polygonal line that bends at a point having a natural period of 1.5 seconds to obtain an average of the speed responses in a section of a natural period of 0.1 seconds to 2.5 seconds, and in particular, We propose to set the natural period to a point at or near 1.5 seconds.

Further, in the present invention, a plurality of points having a natural period of 0.1 seconds to 2.5 seconds are selected in the above method, and the estimation formula is the velocity response spectrum by a polygonal line connecting the values of the respective points. It is proposed that the equation is approximated to obtain the average of the velocity responses in the section of the natural period of 0.1 seconds to 2.5 seconds.

In the present invention, the natural period of at least 1.5 seconds and 2.5 seconds is selected in the above method, and the natural period of 1.5 seconds and 2.5 seconds is less than 1 second.
We propose to add 3 points.

[0011]

In the approximation of the velocity response spectrum of the ground motion when obtaining the SI value, there is a systematic error in the estimated SI value obtained without changing the preset natural period. Although the number of cycles is relatively large when the number of cycles is two or less, the degree of variation is smaller than the degree of variation of the estimated SI value obtained by the method of the above document even when the set natural period is one point.

The above systematic error can be easily removed by correcting it by a correction equation using a regression coefficient of a regression linear equation in which the estimated SI value is the dependent variable and the SI value obtained from the definition equation is the independent variable. .

Therefore, even if the number of natural periods set in the calculation of the SI value is small, it is possible to obtain highly accurate seismic intensity with a small degree of variation with respect to the target earthquake, and to set the number of natural periods to be set. By increasing the number, the degree of variation becomes smaller and the seismic intensity can be obtained with higher accuracy.

[0014]

The present invention will now be described in detail with reference to the drawings. FIG. 1 conceptually shows the configuration of a control seismograph to which the present invention is applied. Reference numeral 1 is an accelerometer, 2 is an estimated SI value calculation unit, 3 is a regression correction unit, and 4 is a control unit. Estimated SI
The value calculation unit 1 inputs the acceleration of the seismic motion detected by the accelerometer 1 at every sampling time of, for example, about 1/100 second, and calculates a motion equation of a one-degree-of-freedom vibration system in a preset damping constant and natural period. There is a process of calculating the velocity response for each sample every moment by satisfying the calculation and a process of obtaining the maximum value of the velocity response and substituting this maximum value into an estimation formula described in detail below to obtain the estimated SI value. These steps are realized by combining various operation units such as various operation units and filters as disclosed in the above-mentioned documents in hardware, or by software such as a device to which a microcomputer is applied. Can be realized in real time. In addition, the regression correction unit 3 holds the regression coefficient of the regression linear equation having the estimated SI value as the dependent variable and the true SI value as the independent variable as data, as described later, and the estimated SI value calculation unit 1 calculates the estimated SI value. The configuration is such that a value is corrected by a correction equation using a regression coefficient, and this can also be realized in software by a device to which a microcomputer is applied. Based on the corrected SI value corrected by the regression correction unit 3, the control unit 4 controls various systems at the time of an earthquake that is likely to damage the structure and automatically stops the operation. Measures can be taken. As a specific method of such control, as described in the above-mentioned document, an appropriate method such as performing control in consideration of the maximum acceleration can be applied.

As described above, the present invention approximates the velocity response spectrum of seismic motion and estimates the SI value without changing the set natural period. The natural period is set to 1. One of the points from 5 seconds to 2.5 seconds is set to represent the flat portion of the velocity response spectrum, and the estimation formula is that the velocity response spectrum is approximated by a polygonal line that bends at a point with a natural period of 1.5 seconds. A method of obtaining an average of velocity responses in a section of a natural period of 0.1 seconds to 2.5 seconds, a plurality of natural cycles of 0.1 seconds to 2.5 seconds are selected, and an estimation formula is , The velocity response spectrum is approximated by a polygonal line connecting the above points, and a natural period of 0.1 seconds to 2.
And a method for obtaining an average of speed responses in a section of 5 seconds. Next, these methods will be described in detail with reference to examples.

First, the SI value estimating equation set in the estimated SI value calculating unit 1 in the present invention will be described below together with the SI value defining equation and the SI value estimating equation according to the above-mentioned document. First,
As described above, the SI value is the natural period of 0.1 second to 2.
It is defined by the average value of the response speed in the range of up to 5 seconds, and is expressed by the following equation.

[Equation 1]

On the other hand, the method of estimating the SI value shown in the above document, that is, the damping constant of 20% and the natural period of 1.5 seconds, 2.
The estimation formula of the estimated SI value in the method of estimating the SI value by multiplying the larger one of the maximum values of the velocity response of the one-degree-of-freedom vibration system for 5 seconds by a constant is expressed as the following equation. SIk (20) = max [SV (2.5), SV (1.5)] × 1.7 / 2.4 where SV (1.5) and SV (2.5) are the maximum values of the velocity response in the natural period of 1.5 seconds and 2.5 seconds, respectively. Yes, max [a.
b] is an operator for adopting the larger value of a or b, and "20" of SIk (20) is for emphasizing that 20% is adopted as the damping constant. But the same is true.

On the other hand, the estimated SI value obtained by the above method of the present invention is expressed by the following equation. However, the following equation applies when a damping constant of 20% is applied. The natural cycle is a method of setting any one point from 0.1 seconds to 2.5 seconds SI ₁ (20) = SV (T) × 1.7 / 2.4 T is the set natural cycle, 1.5 seconds to 2 The value is up to 5 seconds, and for example, in the case of 1.5 seconds, it is expressed by the following equation. SI ₁ (20) = SV (1.5) × 1.7 / 2.4 In this method, the flat portion of the velocity response spectrum SV is represented by the maximum value of the velocity response in the natural period T as conceptually shown in FIG. The response spectrum has a natural period of 1.
It is approximated by a polygonal line that bends at a point of 5 seconds, and a natural period of 0.
The estimated SI value is obtained by calculating the average of the speed responses in the section of 1 second to 2.5 seconds.

A method for selecting and setting a plurality of points having a natural period of 0.1 to 2.5 seconds

[Equation 2] As shown in the conceptual diagram of FIG. 3, the above equation defines the section of the natural period of 0.1 second to 2.5 seconds of the velocity response spectrum by the polygonal line connecting the values of the points of the plurality of selected natural periods. It is a general expression that approximates and averages the velocity response in this section,
The maximum value of Tj + 1 is 2.5 (seconds). When the natural period set in this method is two points of 1.5 seconds and 2.5 seconds, it is represented by the following equation and is shown in FIG. SI ₂ (20) = [SV (1.5) × 0.7 + {SV (1.5) + SV (2.5)} ×
0.5] /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 organized based on the records used in "Research Report on Information for Judgment of Emergency Measures during Earthquakes" (April 1991, Japan Gas Association) We have used 40 examples of earthquake records observed in a famous earthquake.

First, FIGS. 5 to 7 show SIk (20), SI ₁ (20), and SI ₂ (20) obtained from the above-mentioned seismic records, and SI values obtained by the definition formula (hereinafter, simply SI or SI It is shown in comparison with the value). In these figures, the horizontal axis is the SI value, so the estimated SI value is SI
If there is a linear relationship with the value, especially with a linear relationship of gradient 1, the estimation accuracy is good and there is no systematic error. From FIG. 5, although SIk (20) has a relatively large variation,
When the relationship with SI is approximated by a straight line on average, the slope of the straight line Lk becomes approximately 1, and it can be seen that no systematic error is included. In addition, hereinafter, the straight line of the gradient 1 is shown as L ₀ . 6 and 7, SI ₁ (20) and SI ₂ (20) have a linear relationship with SI, but the slopes of the straight lines L ₁ and L ₂ are different from 1, and therefore systematic. It can be seen that the error is included.
Therefore, these values cannot be directly used as the estimated SI value. However, it can be seen that the variation in value is smaller than SIk (20). Incidentally, in order to compare SI ₂ (20) and SIk (20), if SI ₂ (20) / SI is shown on the horizontal axis and SIk (20) / SI is shown on the vertical axis as shown in FIG. Is about 1.0, the latter is about 1.0, and the range of variation is larger in the latter. Incidentally, these numerical points and SIi (20) (i ≧ 3) will be described later.

Next, a correction formula for setting the regression correction unit 3 to remove the systematic error will be described. First, SIi (20) (where i = k, 1,2,
If the median of (...) is represented by SIi, and the regression linear equation obtained by the regression analysis is represented by SIi = aSI + b, S
The establishment variable [SIi (20)] of Ii (20) can be expressed by the following equation. [SIi (20)] = aSI + b + ε (where ε is a residual residual probability variable) The regression coefficients a and b of the above linear equation of regression apply the least squares method, and SIi (20) and SIi for many earthquake records It can be obtained as a value that minimizes the sum of the squares of the differences. Conversely, the regression coefficients a and b of the above linear regression equation
Is determined, the corrected SI value sii obtained by removing the systematic error from each estimated SI value can be expressed as the following expression, and this expression is a correction expression set in the regression correction unit 3. sii = SIi (20) / a + b / a

FIGS. 9 to 11 show values obtained by correcting the estimated SI values SIk (20), SI ₁ (20) and SI ₂ (20) shown in FIGS. 5 to 7, that is, sik and si. ₁ and si ₂ are shown in comparison with SI. Further, in these figures, the standard deviation σ of the residual ε is entered to show the degree of variation.

As shown in FIGS. 10 and 11, SI
The systematic error of ₁ (20) and SI ₂ (20) is removed by the correction formula, and when the relation of these si ₁ and si ₂ with SI is approximated by a straight line on average, these straight lines L ₂ ′, L gradient of ₃ 'is 1, overlapping with the straight line L _0. Also, as shown in FIG.
The straight line Lk ′ indicating the relationship between ik and SI is SIk (2
Like 0), it overlaps with the straight line L _0, and sik and SIk (20) are
The degree of variation is also the same. And sik, si ₁ , s
The above standard deviations showing the degree of variation of i ₂ are 8.79 respectively.
(cm / s), 6.43 (cm / s) and 3.38 (cm / s), showing that sik has the most variation.

Therefore, from the above, even if the natural period to be set in the method of the present invention is set to one point, by performing the correction, the degree of variation with respect to the target earthquake is small and the earthquake motion with high accuracy is obtained. It is possible to obtain the intensity, and if the natural period is set to 2 points and the velocity response spectrum is approximated by a line using the values of these points, it is possible to obtain a more accurate seismic intensity with less variation. Recognize.

An embodiment of SIi (20) (i ≧ 3) will now be described with reference to FIGS. First, FIG.
Shows the relationship between si ₃ and SI obtained by correcting SI ₃ (20) (set natural period T (second): 1.0, 1.5, 2.5) by a correction formula. Further, FIG. 13 shows a relationship between si ₃ and SI obtained by correcting SI ₃ (20) (set natural period T (second): 0.7, 1.5, 2.5) by the above correction formula. See also FIG.
4 is SI ₄ (20) (set natural period T (second): 0.44, 0.8, 1.
5 and 2.5) are corrected by the correction formula to show the relationship between si ₄ and SI. Further, FIG. 15 shows a relationship between si ₅ and SI obtained by correcting SI ₅ (20) (set natural period T (second): 0.44, 0.8, 1.5, 2.0, 2.5) by a correction formula. .

From these figures, it can be seen that by increasing the number of set natural periods to 3 or more, the degree of variation is further reduced and the correlation with SI is increased. Then, as shown in FIGS. 12 and 13, it can be seen that even if the set number of natural periods is the same, the degree of variation varies depending on the positions of the points of those natural periods. See also FIG.
4, as shown in FIG. 15, when the number of natural periods to be set becomes 4, and further 5, the correlation with SI becomes very high. It can be seen that it is not a good idea in consideration of the time required for calculation in the value calculation unit 2. However, when the estimated SI value calculation unit 2 has sufficient spare capacity for the calculation speed,
It is also possible to further increase the number of set natural periods to obtain better correlation.

In setting a plurality of natural periods,
Although it is possible to set each natural period to an appropriate point from 0.1 to 2.5 seconds, the flat part of the velocity response spectrum SV starts at or near 1.5 seconds, and SI
Considering the definition formula of the value, it is preferable that the plurality of natural periods to be set include at least 1.5 seconds and 2.5 seconds. In addition, it is preferable to select a point on the long period side other than the natural period other than the above, particularly near 1.5 seconds where the SV value is small for 1.5 seconds or less.

The degree of variation of the estimated SI value in each of the above embodiments and the regression coefficients a and b of the above linear regression equation
The values of are shown in Table 1. Estimated S before and after regression correction
FIG. 16 shows the relationship between the degree of variation in the I value and the set number of natural periods. However, in Table 1 and FIG. 16, the degree of variation is not the standard deviation σ, but a value obtained by dividing the standard deviation σ by the average value (μ = 38 cm / sec) of the SI values of the 40 earthquake records, that is, It is represented by the coefficient of variation (σ / μ). Further, in FIG. 16, x indicates a variation coefficient before correction, ■ indicates a variation coefficient after correction, and □ indicates a variation coefficient of the estimated SI value according to the above-mentioned document.

[Table 1]

The following are clear from Table 1 and FIG. When the set number of natural periods is 1, the coefficient of variation of the estimated SI value is larger than the coefficient of variation of the estimated SI value according to the method described in the above document, but by correcting with the regression coefficients a and b, It can be smaller than the latter coefficient of variation. When the number of set natural periods is two, the coefficient of variation of the estimated SI value is slightly smaller than the coefficient of variation of the estimated SI value according to the method described in the above document, but it depends on the regression coefficients a and b. By correcting, it is possible to make the coefficient of variation smaller than the latter. When the number of set natural periods is three or more, the coefficient of variation of the estimated SI value is much smaller than the coefficient of variation of the estimated SI value according to the method of the above document as it is, and is corrected by the regression coefficients a and b. By doing so, the coefficient of variation can be made smaller than the latter.

The broken line in FIG. 16 is a reference coefficient of variation introduced to obtain a reference value of the variation of the estimated SI value, and the reference coefficient of variation is the above earthquake record 40 example,
The velocity response spectrum is standardized so that each SI value becomes 1, statistically processed to obtain a standardized velocity response spectrum, and the SI value obtained from the average value and the SI value obtained from (average value + standard deviation) The difference is used as the standard of variation. That is, FIG. 17 shows the standardized velocity response spectrum obtained from the 40 earthquake record examples, the solid line is the average value, and the broken line is the average value ± standard deviation. Each standardized velocity response spectrum is filled with the SI value obtained from these by the definition formula, and the deviation by the standard deviation of the standardized velocity response spectrum corresponds to a change of about 25% in SI value. You can see that Therefore, all the data of the earthquake record is 25
The standard deviation σ of SI value calculated assuming that it varies only by% is σ = 10.79 (cm / s), and the average value μ = 38 cm / sec, the coefficient of variation (σ / μ) is 0.284. I am trying.

FIG. 18 shows the standard deviation of the variation of the standardized velocity response spectrum on a common logarithm. From the figure, the variation of the standardized velocity response spectrum shows that the natural period 1.
It can be seen that it is the smallest around 5 seconds. Therefore, SI
₁ (20) It can be seen that the best accuracy is obtained when the natural period in the calculation is 1.5 seconds or in the vicinity thereof.

In the above description, the damping constant to be set is SI.
Although 20% in the definition formula of the value is set, a value other than 20% may be set as the damping constant in some cases by using the method of correcting by the correction formula using the regression coefficient as described above. it can.

[0034]

As described above, the present invention has the following effects. It is possible to reduce the variation in the estimated SI value as compared with the method of the above-mentioned document in which the larger one of the maximum values of the velocity response of the natural period of 1.5 seconds or 2.5 seconds is selected. In addition, the systematic error can be removed by regression correction, and the seismic intensity can be measured with high accuracy. SI is set by setting the number of natural cycles to be 1
The calculation time required to estimate the value can be shortened. The accuracy can be further improved by setting the number of natural periods to be set to 3 or more.

[Brief description of drawings]

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

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

FIG. 3 is an explanatory diagram showing a second approximation method of the velocity response spectrum in the method of the present invention.

FIG. 4 is an explanatory diagram showing a third approximation method of the velocity response spectrum in the method of the present invention.

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

FIG. 6 is an explanatory diagram showing a relationship between SI ₁ (20) and SI.

FIG. 7 is an explanatory diagram showing a relationship between SI ₂ (20) and SI.

FIG. 8 is an explanatory diagram showing a relationship between SIk (20) and SI ₂ (20).

FIG. 9 is an explanatory diagram showing a relationship between regression-corrected SIk (20) and SI.

FIG. 10 is an explanatory diagram showing a relationship between regression-corrected SI ₁ (20) and SI.

FIG. 11 is an explanatory diagram showing the relationship between regression-corrected SI ₂ (20) and SI.

FIG. 12 is an explanatory diagram showing the relationship between regression-corrected SI ₃ (20) and SI.

FIG. 13 is an explanatory diagram showing a relationship with SI ₃ (20) of FIG. 12 by performing regression correction on SI ₃ (20) having a different natural period.

FIG. 14 is an explanatory diagram showing the relationship between regression-corrected SI ₄ (20) and SI.

FIG. 15 is an explanatory diagram showing the relationship between regression-corrected SI ₅ (20) and SI.

FIG. 16 is an explanatory diagram showing the relationship between the degree of variation in estimated SI values before and after regression correction and the set number of natural periods.

FIG. 17 is an explanatory diagram showing a normalized velocity response spectrum obtained from 40 earthquake record examples.

FIG. 18 shows the standard deviation of variations in the normalized velocity response spectrum of FIG.

[Explanation of symbols]

 1 Accelerometer 2 Estimated SI value calculation unit 3 Regression correction unit 4 Control unit

Claims (8)

[Claims] 1. An estimation formula in which a seismic motion acceleration is input, a velocity response is obtained momentarily by performing an operation satisfying a set damping constant and a motion equation of a one-degree-of-freedom vibration system in a natural period, and a maximum value thereof is set in advance. In the method of obtaining the estimated SI value by substituting into the above, in the desired setting conditions, from the SI value obtained by the definition equation for a large number of earthquake records and the estimated SI value obtained by the above estimation equation, the estimated SI value is a dependent variable, The regression coefficient of the linear regression equation with the SI value obtained from the definition formula as the independent variable is calculated in advance, and the estimated SI value obtained by inputting the acceleration of the target earthquake motion is corrected by the correction formula using the above regression coefficient. Method for measuring seismic intensity for control characterized by: 2. The damping constant is 2 in the defining equation of SI value.
The seismic intensity measuring method for control according to claim 1, wherein 0% is set. 3. The damping constant is 2 in the defining equation of SI value.
The method for measuring seismic intensity for control according to claim 1, wherein the value other than 0% is set. 4. The natural period is set to any one point from 1.5 seconds to 2.5 seconds, the flat portion of the velocity response spectrum is represented by the value of this point, and the estimation formula is the velocity response spectrum. 4. An equation for approximating a velocity curve in a section of a natural period of 0.1 seconds to 2.5 seconds by approximating a curve with a line bent at a natural cycle of 1.5 seconds to obtain an average of velocity responses. Method of seismic intensity for control of earthquake 5. The method for measuring seismic intensity for control according to claim 4, wherein the natural period is set to a point at or near 1.5 seconds. 6. The natural period selects a plurality of points from 0.1 seconds to 2.5 seconds, and the estimation formula is that the velocity response spectrum is approximated by a polygonal line connecting the values of the respective points, and a natural period of 0.
4. The method for measuring seismic intensity for control according to claim 1, wherein the expression is an equation for averaging velocity responses in a section of 1 second to 2.5 seconds. 7. The method for measuring seismic intensity for control according to claim 6, wherein natural periods of at least 1.5 seconds and 2.5 seconds are selected. 8. The natural period is set to 3 points by adding 1 point of 1 second or less to 1.5 seconds and 2.5 seconds.
Seismic intensity measurement method for control described