How to create simulated earthquake motion

Abstract

To provide a method for creating simulated earthquake motion that has been verified against the target spectrum and is within the excitation limits of the excitation device.SOLUTION: The method for creating simulated earthquake motion includes a ninth step (S109) of determining that a candidate simulated earthquake motion that is created in a sixth step (S106) of testing to create a candidate simulated earthquake motion is an excitation limit spectrum (6) of the excitation device or less, and when the created candidate simulated earthquake motion exceeds the excitation limit spectrum (6), correcting the created candidate simulated earthquake motion components in the vibration range that exceed the excitation limit spectrum (6) of the vibration excitation device and recreating the simulated earthquake motion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for generating simulated earthquake motion. [Background technology]

[0002] Seismic testing is a method for investigating the earthquake durability of structures and equipment. In this test, a structure, equipment, or part of it is used as a test specimen, which is placed on a vibration device such as a shaker or shaking table, and the seismic loads expected to act on the structure or equipment are input. The seismic performance, which is the durability of structures and equipment against earthquakes, and the seismic loads acting on structures and equipment are often presented as response spectra. As the seismic motion used as input in seismic testing, time history waveforms of simulated earthquake motions that conform to these response spectra (called target spectra) are created.

[0003] When conducting seismic tests, it is confirmed in advance that the acceleration, velocity, and displacement components of the simulated earthquake motion created are below the excitation limits of the acceleration, velocity, and displacement of the vibration device used in the seismic test, and that excitation is possible.If the confirmation reveals that the simulated earthquake motion exceeds the excitation limits, measures are taken such as modifying the simulated earthquake motion or changing the vibration device used in the seismic test so that excitation is possible.

[0004] Due to the damage to structures and equipment caused by recent earthquakes and the ripple effects of such damage, the seismic performance required of structures and equipment continues to increase. As a result, seismic tests are increasingly being required to evaluate the seismic performance of structures and equipment up to excitation conditions close to the limits of the excitation performance of the vibration device, which limits the conditions under which the simulated earthquake motion used as input can be established.

[0005] Patent Document 1 proposes a vibration testing device that generates time-history waveforms of simulated earthquake motion that are calibrated against a target spectrum and fall within the excitation limit of the vibration testing device. This vibration testing device includes a vibration exciter that mounts a test specimen and a drive mechanism that vibrates the vibration exciter in at least two different directions in a horizontal plane. The vibration testing device also includes a control unit that controls the drive mechanism of the vibration exciter. The vibration testing device also includes a calculation unit that generates vibration waveforms to be applied to the vibration exciter and provides the generated waveforms to the control unit. The vibration testing device also includes a step of verifying whether the excitation ranges of the two generated waveforms fall within the excitation range of the vibration exciter, and a step of generating two waveforms again if the excitation range does not fall within the excitation range. In this way, the vibration testing device generates simulated earthquake motion that is calibrated against the target spectrum and falls within the excitation limit of the vibration exciter. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-96199 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, in the conventional method for generating simulated earthquake motion, after the step of generating simulated earthquake motion that has been verified against the target spectrum, it is determined whether the generated simulated earthquake motion falls within the excitation limit range of the excitation device. Therefore, in order to generate simulated earthquake motion that has been verified against the target spectrum and falls within the excitation limit range of the excitation device, a large number of trials are required to find a stable point for the processing of the two steps.

[0008] The present invention has been invented to solve the above problems, and its object is to provide a method for generating simulated earthquake motion that can efficiently generate simulated earthquake motion that has been verified against a target spectrum and falls within the excitation limit range of a vibration excitation device. [Means for solving the problem]

[0009] A method for generating simulated earthquake motion according to one aspect of the present invention includes the steps of: Create candidate simulated earthquake motions based on the creation conditions, and then verify the candidate simulated earthquake motions. A method for creating simulated earthquake motion, comprising: As values ​​to be used in the test, a response spectrum error tolerance expressed as a tolerance for the ratio of the amplitude of the response spectrum of the candidate simulated earthquake motion to the amplitude of the target spectrum, and a vibration limit spectrum of a vibration device are set, and a spectrum excess ratio obtained as the amplitude ratio of the response spectrum of the candidate simulated earthquake motion to the vibration limit spectrum is calculated, and the test is carried out when, in the created result of the candidate simulated earthquake motion, the amplitude ratio of the response spectrum of the candidate simulated earthquake motion to the amplitude of the target spectrum satisfies the tolerance for response spectrum error, and The candidate simulated earthquake motion is The aforementioned Below the excitation limit spectrum and if the amplitude ratio of the response spectrum of the candidate simulated earthquake motion to the amplitude of the target spectrum does not satisfy the tolerance for the response spectrum error, the creation conditions for the candidate simulated earthquake motion are corrected by multiplying the Fourier amplitude spectrum by the ratio of the target spectrum to the response spectrum of the candidate simulated earthquake motion, If the candidate simulated earthquake motion exceeds the excitation limit spectrum, The creation conditions for the candidate simulated earthquake motion are corrected by multiplying the Fourier amplitude spectrum by the inverse of the spectral excess ratio in the frequency range where the spectral excess ratio exceeds 1, and the candidate simulated earthquake motion is created again based on the corrected creation conditions and the test is performed, and if the creation result of the candidate simulated earthquake motion satisfies the test conditions, the candidate simulated earthquake motion is acquired as the simulated earthquake motion. . [Effects of the Invention]

[0010] According to the present invention, in the step of creating simulated earthquake motion, it is also verified that the simulated earthquake motion does not exceed the excitation limit of the excitation device. This makes it possible to efficiently create simulated earthquake motion that has been verified against the target spectrum and falls within the excitation limit of the excitation device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing the system configuration of a simulated earthquake motion creating device according to an embodiment. [Figure 2] FIG. 2 is a flowchart showing a method for creating a simulated earthquake motion according to the embodiment. [Figure 3A] FIG. 3A is a diagram showing a part of input data in the method for creating a simulated earthquake motion according to the embodiment, and shows an envelope function. [Figure 3B] FIG. 3B is a diagram showing a part of input data in the method for creating a simulated earthquake motion according to the embodiment, and shows a target spectrum and an excitation limit spectrum. [Figure 4A]FIG. 4A is a diagram showing a part of the output results in the method for creating a simulated earthquake motion according to the embodiment, and shows the target spectrum, excitation limit spectrum, and response spectrum of the simulated earthquake motion. [Figure 4B] FIG. 4B is a diagram showing a part of the output result in the method for creating a simulated earthquake motion according to the embodiment, showing a time history waveform. [Figure 5] FIG. 5 is a diagram showing an example of an excitation limit spectrum setting screen displayed by the display unit according to the embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a display screen of the simulated earthquake motion creation result displayed by the display unit according to the embodiment. [Figure 7] FIG. 7 is a flowchart showing a method for creating simulated earthquake motion using a conventional method. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the text and drawings. The various specific configurations shown in the present invention are not limited to the embodiments described here, and can be appropriately combined or improved within the scope of the present invention. Furthermore, elements not directly related to the present invention are omitted from the illustrations.

[0013] <<How to create simulated earthquake motion>> The method for creating simulated earthquake motion according to this embodiment will be described with reference to Figures 1 to 4. Figure 1 is a block diagram showing the system configuration of an apparatus for creating simulated earthquake motion using the method for creating simulated earthquake motion according to this embodiment. Figure 2 is a flowchart showing the procedure for creating simulated earthquake motion when the method for creating simulated earthquake motion according to this embodiment is adopted. Figure 3A is a diagram showing some input data in the method for creating simulated earthquake motion according to this embodiment, illustrating an envelope function. Figure 3B is a diagram showing some input data in the method for creating simulated earthquake motion according to this embodiment, illustrating a target spectrum and an excitation limit spectrum. Figure 4A is a diagram showing some output data in the method for creating simulated earthquake motion according to this embodiment, illustrating the target spectrum, excitation limit spectrum, and response spectrum of the simulated earthquake motion. Figure 4B is a diagram showing some output data in the method for creating simulated earthquake motion according to this embodiment, illustrating a time history waveform.

[0014] <<Simulated earthquake motion generator 1>> First, the system configuration of an apparatus for generating simulated earthquake motion will be described using FIG. 1. The simulated earthquake motion generation apparatus 1 shown in FIG. 1 is composed of a storage unit 101 and a calculation unit 102, and is connected to an input / output display unit 2. A user of the simulated earthquake motion generation apparatus 1 inputs input data Da1, outputs output data Da2, and operates the simulated earthquake motion generation apparatus 1 via the input / output display unit 2. The input data Da1 is stored in the storage unit 101. When the generation of simulated earthquake motion is executed, the necessary data is sent from the storage unit 101 to the calculation unit 102. The calculation unit 102 then performs calculations to generate the simulated earthquake motion in accordance with the procedure for generating the simulated earthquake motion, which will be described later. The calculation unit 102 is composed of a microcomputer and its peripheral devices. The results of the calculations in the calculation unit 102 are stored in the storage unit 101. A user of the simulated earthquake motion generation apparatus 1 can check the output data Da2 on the input / output display unit 2.

[0015] The input data Da1 is roughly divided into conditions for generating earthquake motion and conditions for testing. The conditions for generating earthquake motion include the initial random number of the phase spectrum, the envelope function 4 (see Figure 3A), the target spectrum 5 (see Figure 3B), and the allowable number of corrections for the Fourier amplitude. Set , used for testing value as 、 Target Spectrum The amplitude of of candidate simulated earthquake motions for Represents the tolerance of the response spectrum amplitude ratio Set the response spectrum error tolerance and excitation limit spectrum 6 (see Figure 3B).

[0016] Here, simulated earthquake motion before verification during the simulated earthquake motion creation stage is referred to as the candidate simulated earthquake motion. Envelope function 4 is set to specify the time characteristics of the simulated earthquake motion to be created, and is a function of time and normalized amplitude as shown in Figure 3A. Target spectrum 5 and excitation limit spectrum 6 are defined as the relationship between frequency components and earthquake motion amplitude components as shown in Figure 3B, where frequency is used as the frequency component and velocity is used as the earthquake motion amplitude component. Target spectrum 5 is a response spectrum that specifies the seismic performance required of structures and equipment and the seismic load acting on structures and equipment. Excitation limit spectrum 6 is a response spectrum that indicates the possible excitation range of the excitation device.

[0017] The output data Da2 includes the response spectrum 7 of the created simulated earthquake motion (see Figure 4A), a time history waveform 8 (see Figure 4B), maximum acceleration, maximum velocity, maximum displacement, and a spectral ratio calculated as the ratio of the response spectrum 7 of the simulated earthquake motion to the target spectrum 5 or the excitation limit spectrum 6. As an example of the output data Da2, Figure 4A shows the response spectrum 7 of the created simulated earthquake motion (solid line) together with the target spectrum 5 (dotted line) and the excitation limit spectrum 6 (dashed line). Figure 4B shows the acceleration time history waveform 8 of the simulated earthquake motion.

[0018] <<Procedure for creating simulated earthquake motion>> Next, the procedure for generating simulated earthquake motions in this embodiment will be explained using Figure 2. Note that the method for generating simulated earthquake motions in this embodiment partially uses a technique called the spectral fitting method (see, for example, "New Introduction to Spectral Analysis of Earthquake Motions" by Yoshihiko Osaki, Kajima Publishing). Therefore, the specific calculations of the spectral fitting method will not be explained here. This spectral fitting method, in particular, focuses on a method for generating simulated earthquake motions in which the phase characteristics of the simulated earthquake motions are set based on uniform random numbers. The spectral fitting method sets complex Fourier coefficients consisting of a Fourier amplitude spectrum and a Fourier phase spectrum, and then obtains an acceleration time history waveform by performing an inverse Fourier transform of the complex Fourier coefficients. The obtained time history waveform is multiplied by an envelope function to generate candidate simulated earthquake motions with time-dependent characteristics, and the response spectrum 7 of the created candidate simulated earthquake motion is calculated. The degree of fit between the obtained response spectrum 7 of the candidate simulated earthquake motion and the target response spectrum is then tested. If the test conditions are met, the candidate simulated earthquake motion is adopted as the simulated earthquake motion, and the process of generating the simulated earthquake motion is completed. On the other hand, if the test conditions are not satisfied, the Fourier amplitude spectrum is corrected by the ratio of the response spectrum 7 of the candidate simulated earthquake motion to the target response spectrum, and the creation and testing of the candidate simulated earthquake motion are repeated from the inverse Fourier transform procedure.

[0019] <<Process flow for creating simulated earthquake motion>> In creating the simulated earthquake motion in this embodiment, the calculation unit 102 first reads the input data Da1 shown in Fig. 2 in the setting of the creation conditions of the simulated earthquake motion and the excitation limit spectrum 6 in the first step S101 shown in Fig. 2. As the creation conditions of the simulated earthquake motion, the initial random number of the phase spectrum and the allowable number of corrections of the Fourier amplitude spectrum are set.

[0020] Next, in the second step S102, in which the Fourier amplitude initial conditions are set, the calculation unit 102 creates a Fourier amplitude spectrum of the initial conditions. There are various methods for providing the initial Fourier amplitude spectrum, but one example is to use a normalized version of the target spectrum 5 set by the input data Da1 shown in FIG. 2.

[0021] Next, in the sinusoidal wave synthesis in the third step S103, the calculation unit 102 calculates complex Fourier coefficients composed of the Fourier amplitude spectrum obtained in the second step S102 and the Fourier phase spectrum obtained by generating uniform random numbers using the initial random numbers of the phase spectrum set in the input data Da1 shown in Fig. 1. The calculated complex Fourier coefficients are subjected to an inverse Fourier transform to obtain an acceleration time history waveform.

[0022] Next, in calculating the time function in the fourth step S104, the calculation unit 102 obtains the acceleration time history waveform of the candidate simulated earthquake motion by multiplying the acceleration time history waveform obtained in the third step S103 by the envelope function 4 set in the input data Da1 shown in Figure 1.

[0023] Next, in the response spectrum calculation in the fifth step S105, the calculation unit 102 performs a response spectrum analysis on the acceleration time history waveform of the candidate simulated earthquake motion obtained in the fourth step S104, and calculates the response spectrum 7 of the candidate simulated earthquake motion.

[0024] Next, in the sixth step S106, in determining whether the test condition for the target spectrum 5, that is, the response spectrum 7 of the candidate simulated earthquake motion is equal to or less than the excitation limit spectrum 6, is satisfied, the calculation unit 102 determines whether the response spectrum 7 of the candidate simulated earthquake motion satisfies the allowable value of the response spectrum error of the candidate simulated earthquake motion with respect to the target spectrum 5 and is equal to or less than the excitation limit spectrum 6. In this determination, the spectrum excess ratio, which is found as the amplitude ratio of the response spectrum 7 of the candidate simulated earthquake motion to the excitation limit spectrum 6, is calculated.

[0025] If the response spectrum 7 of the candidate simulated earthquake motion satisfies the judgment conditions of the sixth step S106, the candidate simulated earthquake motion is adopted as the simulated earthquake motion, and the process proceeds to the seventh step S107 in which the output data Da2 shown in Figure 1 is written out, and the simulated earthquake motion creation process is completed.

[0026] On the other hand, if the response spectrum 7 of the candidate simulated earthquake motion does not satisfy the judgment condition in the sixth step S106, the calculation unit 102 proceeds to the eighth step S108 and judges whether the number of trials i has reached the allowable number of corrections N of the Fourier amplitude. If the number of trials i has not reached the allowable number of corrections N of the Fourier amplitude, the calculation unit 102 corrects the Fourier amplitude in the ninth step S109.

[0027] Thereafter, in a tenth step S110, the calculation unit 102 increments the number of trials i by 1, and returns to the sine wave synthesis in the third step S103 using the corrected Fourier amplitude to generate candidate simulated earthquake motions.

[0028] In the correction of the Fourier amplitude spectrum, if the judgment conditions for target spectrum 5 are not satisfied, the Fourier amplitude spectrum is corrected by multiplying the Fourier amplitude spectrum used in the step by the ratio of target spectrum 5 to response spectrum 7 of the candidate simulated earthquake motion. Also, if the judgment conditions for excitation limit spectrum 6 are not satisfied, the Fourier amplitude spectrum is corrected by multiplying the Fourier amplitude spectrum used in the step by the ratio of excitation limit spectrum 6 to response spectrum 7 of the candidate simulated earthquake motion in the frequency range that does not exceed excitation limit spectrum 6 in the response spectrum 7 of the created candidate simulated earthquake motion. In other words, if the created simulated earthquake motion does not satisfy the inspection conditions, the tolerance for response spectrum error is Reciprocal of (upper and lower limits) The conditions for creating candidate simulated earthquake motions are corrected by multiplying the Fourier amplitude spectrum by the inverse of the spectral excess ratio in the frequency range where the spectral excess ratio exceeds 1.

[0029] On the other hand, if the number of trials i reaches the allowable number of Fourier amplitude corrections N in the eighth step S108, the calculation unit 102 determines in the eleventh step S111 that the study on generating simulated seismic motion using the initial random numbers of the phase spectrum specified in the input data Da1 has diverged. In this case, the calculation unit 102 updates the initial random numbers in the twelfth step S112 by changing the initial random numbers of the phase spectrum set in the input data Da1 shown in FIG. 1 to different values. Thereafter, the Fourier phase spectrum is calculated based on the updated initial random numbers, and the sine wave synthesis in the third step S103 is performed again.

[0030] <<Example of the system input and output screens>> Next, Figs. 5 and 6 show examples of an input screen and an output screen, respectively, of a system to which the method for creating simulated earthquake motion of the present invention is applied.

[0031] FIG. 5 is a diagram showing an excitation limit spectrum setting screen 9 as an example of displaying the simulated earthquake motion creation conditions and the excitation limit spectrum 6 settings shown in the first step S101 of FIG. 2 on the input / output display unit 2 of FIG. 2 in the simulated earthquake motion creation method of this embodiment. The excitation limit spectrum setting screen 9 is configured with an excitation limit spectrum input method selection button 10, a response spectrum frequency axis display condition setting button 11, a response spectrum amplitude display condition setting button 12, an excitation limit spectrum input table 13, and an illustration of the excitation limit spectrum 6 and target spectrum 5. First, the input method of the excitation limit spectrum 6 is selected with the excitation limit spectrum input method selection button 10. When "Table" is selected with the excitation limit spectrum input method selection button 10, the frequency and amplitude data of the excitation limit spectrum 6 are entered into the excitation limit spectrum input table 13. When "DB reference" is selected with the excitation limit spectrum input method selection button 10, the excitation limit spectrum data of the vibration device to be used in the vibration test, which has been prepared in advance, is loaded. In other words, the data of the excitation device for which the excitation limit spectrum 6 has been set in advance and the excitation limit conditions of the excitation device are selected from the database. The response spectrum frequency axis display condition setting button 11 sets the frequency axis referenced in the excitation limit spectrum input table 13 and in the illustration of the excitation limit spectrum 6 and target spectrum 5. The response spectrum amplitude display condition setting button 12 similarly sets the amplitude of the response spectrum 7 of the simulated earthquake motion. After the data for the excitation limit spectrum 6 has been entered, pressing the display execution button causes the excitation limit spectrum 6 to be displayed in the illustration of the excitation limit spectrum 6 and target spectrum 5 together with the separately set target spectrum 5.

[0032] Here, as a condition for generating simulated earthquake motion, the response spectrum (referred to as the allowable target spectrum), which is obtained by adding the allowable value for the response spectrum error to the target spectrum 5 set in the first step S101 of Figure 2, must be set to an amplitude smaller than the excitation limit spectrum 6. However, the target spectrum 5 is determined by the seismic performance required of the structure and equipment and the seismic load acting on the structure and equipment. In contrast, the excitation limit spectrum 6 is determined as the range of excitation possible with the excitation device, and the allowable target spectrum is not necessarily smaller than the excitation limit spectrum 6. If the allowable target spectrum exceeds the excitation limit spectrum 6, it must be corrected so that the allowable target spectrum is equal to or smaller than the excitation limit spectrum 6. In other words, the target / excitation limit spectrum ratio is calculated as the amplitude of the target spectrum 5 relative to the amplitude of the excitation limit spectrum 6. If the product of the target / excitation limit spectrum ratio and the allowable value for the response spectrum error exceeds 1, the allowable target spectrum must be corrected so that it is equal to or smaller than the excitation limit spectrum 6.

[0033] The correction methods that can be presented on the display screen include a correction method of re-registering the input data of the target spectrum 5, a correction method of removing frequency components in the target spectrum 5 that exceed the excitation limit spectrum 6, and a correction method based on the excitation limit spectrum 6.

[0034] In the correction method for removing frequency components in the target spectrum 5 that exceed the excitation limit spectrum 6, the amplitude of the frequency range of the target spectrum 5 that exceeds the excitation limit spectrum 6 is corrected to 0 using the following equation 1. In other words, when a correction method for removing the amplitude of the target spectrum 5 is specified, the range for removing the amplitude is specified, and the target spectrum 5 is calculated with the amplitude components in the specified range removed.

[0035]

number

[0036] where k is the frequency, S vT is the target spectrum, Ra is the response spectrum error tolerance, S v L indicates the excitation limit spectrum.

[0037] In addition, in the method of correction based on excitation limit spectrum 6, the target spectrum 5 is corrected using the following equation 2 so that the allowable target spectrum matches the excitation limit spectrum 6. In other words, when the method of correction based on the excitation limit spectrum 6 is specified, the amplitude of the target spectrum 5 is corrected as the value obtained by subtracting the allowable value of the response spectrum error from the excitation limit spectrum 6 for components in the frequency range that exceed the excitation limit of the vibration device.

[0038]

number

[0039] where k is the frequency, S v T is the target spectrum, Ra is the response spectrum error tolerance, S v L indicates the excitation limit spectrum.

[0040] <<Results of simulated earthquake motion>> 6 is an example of the simulated earthquake motion creation results displayed on the input / output display unit 2 of FIG. 1 in accordance with the method for creating simulated earthquake motion according to this embodiment, and shows a simulated earthquake motion creation result display screen 14. The simulated earthquake motion creation result display screen 14 is composed of a response spectrum frequency axis display condition setting button 11, a response spectrum amplitude display condition setting button 12, a summary 15 of the simulated earthquake motion creation results, a plot execution button, and a plot of the response spectrum 7 of the simulated earthquake motion. The response spectrum frequency axis display condition setting button 11 sets the frequency axis. The response spectrum amplitude display condition setting button 12 sets the display conditions for the response spectrum plot. After setting, by pressing the plot execution button, the response spectrum 7 of the simulated earthquake motion is displayed in the response spectrum plot together with the target spectrum 5 and excitation limit spectrum 6. In addition, the summary 15 of the simulated earthquake motion creation results displays key information about the simulated earthquake motion creation results, such as the spectral ratio of the simulated earthquake motion response spectrum 7 to the target spectrum 5, the spectral ratio of the simulated earthquake motion response spectrum 7 to the excitation limit spectrum 6, the maximum acceleration, the maximum velocity, and the maximum displacement.

[0041] << Conventional method for creating simulated earthquake motion >> For comparison with this embodiment, a method for creating simulated earthquake motion that has been verified against the target spectrum 5 using a conventional method and that falls within the excitation limit range of the vibration excitation device will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the method for creating simulated earthquake motion using the conventional method. In particular, to focus on the differences from the method for creating simulated earthquake motion in this embodiment, reference will be made to the steps in the flowchart of the method for creating simulated earthquake motion in this embodiment shown in Fig. 2.

[0042] In setting the conditions for creating simulated earthquake motion shown in step S201 of Figure 7, the calculation unit 102 sets the initial random number of the phase spectrum, the envelope function 4, the target spectrum 5, the allowable number of corrections for the Fourier amplitude, and the allowable value of the response spectrum error of the simulated earthquake motion relative to the target spectrum 5 as a condition to be used for testing.

[0043] Next, in setting the Fourier amplitude initial conditions shown in step S202 of Fig. 7, the calculation unit 102 performs the same process as the second step S102 shown in Fig. 2. In synthesizing sine waves shown in step S203 of Fig. 7, the calculation unit 102 performs the same process as the third step S103 shown in Fig. 2. In calculating the time function shown in step S204 of Fig. 7, the calculation unit 102 performs the same process as the fourth step S104 shown in Fig. 2. In calculating the response spectrum 7 of the simulated earthquake motion shown in step S205 of Fig. 7, the calculation unit 102 performs the same process as the fifth step S105 shown in Fig. 2.

[0044] Next, in determining whether the test conditions are satisfied in step S206 of Fig. 7, the calculation unit 102 determines whether the response spectrum 7 of the candidate simulated earthquake motion obtained in step S205 satisfies the compatibility conditions for the target spectrum 5. If the response spectrum 7 of the candidate simulated earthquake motion satisfies the determination conditions in step S206, the calculation unit 102 adopts the candidate simulated earthquake motion as the simulated earthquake motion in generating the simulated earthquake motion in step S207 of Fig. 7.

[0045] Next, in setting the excitation possibility conditions shown in step S208 of Fig. 7, the calculation unit 102 sets the excitation limit spectrum 6. Then, in determining whether the response spectrum 7 of the simulated earthquake motion is equal to or less than the excitation limit spectrum 6 shown in step S209 of Fig. 7, the calculation unit 102 determines whether the response spectrum 7 of the simulated earthquake motion obtained in step S207 is equal to or less than the excitation limit spectrum 6 set in step S208. If the response spectrum 7 of the simulated earthquake motion satisfies the determination condition of step S208, the calculation unit 102 adopts the response spectrum 7 of the simulated earthquake motion obtained in step S207 as a simulated earthquake motion that has been verified against the target spectrum 5 and falls within the excitation limit range of the excitation device, and ends the simulated earthquake motion creation process.

[0046] On the other hand, if the response spectrum 7 of the candidate simulated earthquake motion does not satisfy the judgment condition in step S206 of Fig. 7, the calculation unit 102 determines in step S210 of Fig. 7 whether the number of trials i has reached the allowable number of corrections N of the Fourier amplitude, similar to the seventh step S107 shown in Fig. 2. If the number of trials i in step S210 has not reached the allowable number of corrections N of the Fourier amplitude, the calculation unit 102 corrects the Fourier amplitude in step S211, increments the number of trials i by one in step S212, similar to step S111 shown in Fig. 1, and returns to the sine wave synthesis in step S203 using the corrected Fourier amplitude to generate the candidate simulated earthquake motion.

[0047] 7, if the number of trials i reaches the allowable number of corrections N of the Fourier amplitude, the calculation unit 102 determines that the study of generating simulated earthquake motion in step S213 has diverged. In that case, in reviewing the generation conditions in step S214, the calculation unit 102 changes some of the generation conditions of the simulated earthquake motion set in step S206, and starts the calculation again from setting the initial conditions of the Fourier amplitude in step S202.

[0048] Furthermore, if the response spectrum of the candidate simulated earthquake motion does not satisfy the judgment conditions in step S209 of FIG. 7, the calculation unit 102 reviews the creation conditions shown in step S214 and starts the calculation again from setting the Fourier amplitude initial conditions in step S202.

[0049] As described above, a time history waveform 8 that has been verified against the target spectrum 5 using the conventional method and that is generated based on simulated earthquake motion that falls within the excitation limit of the excitation device is generated. Then, it is determined whether the generated time history waveform 8 falls within the excitation limit of the excitation device. Therefore, even if the verification against the target spectrum 5 is satisfied, a time history waveform 8 that exceeds the excitation limit of the excitation device may be generated. This increases the number of attempts required to generate simulated earthquake motion.

[0050] <<Effects of this embodiment>> In contrast, in the method for creating simulated earthquake motion according to this embodiment, the criteria for determining whether the simulated earthquake motion conforms to the target spectrum 5 and is below the excitation limit of the excitation device are included in the step of creating the simulated earthquake motion. This makes it possible to efficiently create simulated earthquake motion that has been verified against the target spectrum 5 and is within the excitation limit of the excitation device.

[0051] Furthermore, in the method for generating simulated earthquake motion according to this embodiment, if the number of trials reaches the allowable number of corrections for the Fourier amplitude without satisfying the test conditions, the calculation is repeated by specifying an update of the initial random number as a change condition for the generation conditions. This eliminates the need for reviewing the generation conditions as in the conventional method. This reduces the time required for checking the results of the generated simulated earthquake motion and for reviewing and setting the conditions.

[0052] Furthermore, in the method for creating simulated earthquake motion of this embodiment, the magnitude relationship between the target spectrum 5 and the excitation limit spectrum 6, which is an essential condition for simulated earthquake motion that has been verified against the target spectrum 5 and falls within the excitation limit range of the excitation device, is confirmed in the initial setting stage and corrected to an appropriate condition as necessary. Therefore, it is possible to efficiently create simulated earthquake motion that has been verified against the target spectrum 5 and falls within the excitation limit range of the excitation device, compared to conventional methods for creating simulated earthquake motion that do not take the excitation limit spectrum 6 into consideration when creating simulated earthquake motion.

[0053] <<Effects of Differences>> (A) The method for creating simulated earthquake motions determines whether the candidate simulated earthquake motions created in the test of sixth step S106 for creating candidate simulated earthquake motions are equal to or less than excitation limit spectrum 6 of the excitation device. If response spectrum 7 of the candidate simulated earthquake motions does not satisfy the determination condition of sixth step S106, the method for creating simulated earthquake motions includes a step of correcting components of the created candidate simulated earthquake motions in a frequency range that exceeds excitation limit spectrum 6 of the excitation device, and recreating the simulated earthquake motion.

[0054] According to this configuration, in the sixth step S106 of creating the simulated earthquake motion, by also verifying that the created simulated earthquake motion does not exceed the excitation limit spectrum 6 of the excitation device, it is possible to verify the target spectrum 5 and efficiently create simulated earthquake motion that falls within the excitation limit range of the excitation device.

[0055] (B) The method for creating simulated earthquake motion sets, as the test conditions for the candidate simulated earthquake motion to be created, a response spectrum error tolerance value, which is obtained as the amplitude ratio of the response spectrum 7 of the candidate simulated earthquake motion to the amplitude of the target spectrum 5, and an excitation limit spectrum 6. The method for creating simulated earthquake motion calculates a spectrum exceedance ratio, which is obtained as the amplitude ratio of the response spectrum 7 of the candidate simulated earthquake motion to the excitation limit spectrum 6. If the created result of the candidate simulated earthquake motion does not satisfy the test conditions, the method for creating simulated earthquake motion corrects the creation conditions for the candidate simulated earthquake motion by multiplying the Fourier amplitude spectrum by the response spectrum error tolerance value and the reciprocal of the spectrum exceedance ratio in the frequency range where the spectrum exceedance ratio exceeds 1, and then creates and tests the candidate simulated earthquake motion again. If the created result of the candidate simulated earthquake motion satisfies the test conditions, the method for creating simulated earthquake motion acquires the candidate simulated earthquake motion as the simulated earthquake motion.

[0056] According to this configuration, if the results of the simulated earthquake motion generation do not satisfy the testing conditions, the conditions for generating the candidate simulated earthquake motion are automatically corrected, making it possible to efficiently generate simulated earthquake motion that falls within the excitation limits of the excitation device.

[0057] (C) The method for creating simulated earthquake motions involves setting the initial random number of the phase spectrum and the allowable number of corrections of the Fourier amplitude spectrum as conditions for creating the simulated earthquake motions, and then creating candidate simulated earthquake motions.If the results of creating the candidate simulated earthquake motions do not satisfy the testing conditions within the allowable number of corrections of the Fourier amplitude spectrum, the method for creating simulated earthquake motions updates the initial random number of the phase spectrum and creates the candidate simulated earthquake motions again.

[0058] According to this configuration, if the result of creating the candidate simulated earthquake motion does not satisfy the testing conditions within the allowable number of corrections of the Fourier amplitude spectrum, the initial random number of the phase spectrum is updated and the candidate simulated earthquake motion is created again, thereby saving the user the trouble of updating the initial random number and making it possible to efficiently create simulated earthquake motion that falls within the excitation limit range of the excitation device.

[0059] (D) In the method for creating simulated earthquake motion, in a sixth step S106 of setting the test conditions for the candidate simulated earthquake motion, the target / excitation limit spectrum ratio is calculated as the amplitude of the target spectrum 5 relative to the amplitude of the excitation limit spectrum 6. In the method for creating simulated earthquake motion, when the product of the target / excitation limit spectrum ratio and the tolerance for the response spectrum error is 1 or more and exceeds the excitation limit spectrum of the excitation device, three correction methods are presented: a correction method of re-registering the input data for the target spectrum 5, a correction method of removing the amplitude of the target spectrum 5, and a correction method using the excitation limit spectrum 6.

[0060] According to this configuration, when the product of the target / excitation limit spectrum ratio and the tolerance for the response spectrum error is 1 or greater and exceeds the excitation limit spectrum of the excitation device, it is automatically determined that it is not possible to create simulated earthquake motion that falls within the excitation limit range of the excitation device, and it becomes possible to prompt the user for instructions.

[0061] (E) When a correction method for removing the amplitude of target spectrum 5 is specified, the range of amplitude removal is specified and target spectrum 5 is calculated with the amplitude components in the specified range removed. When a correction method using excitation limit spectrum 6 is specified, the simulated earthquake motion is created by correcting the amplitude of target spectrum 5 as the value obtained by subtracting the allowable value for response spectrum error from excitation limit spectrum 6 for components in the frequency range that exceed the excitation limit spectrum 6 of the vibration device.

[0062] According to this configuration, it is possible to efficiently create simulated earthquake motion that falls within the excitation limit range of the excitation device in accordance with the correction method in accordance with the user's instructions.

[0063] (F) The method for creating the simulated earthquake motion is to select data on the excitation device for which the excitation limit spectrum 6 has been set in advance and excitation limit conditions for the excitation device from a database.

[0064] This configuration allows the user to appropriately select data on the vibration exciter and vibration limit conditions for the vibration exciter from the database.

[0065] (G) The method for generating simulated earthquake motion includes a first step S101 of setting the conditions for generating the simulated earthquake motion and the excitation limit spectrum 6. The method for generating simulated earthquake motion includes a second step S102 of generating a Fourier amplitude spectrum of the initial conditions and setting the Fourier amplitude initial conditions. The method for generating simulated earthquake motion includes a third step S103 of calculating complex Fourier coefficients composed of the Fourier amplitude spectrum of the initial conditions and a Fourier phase spectrum obtained by generating uniform random numbers using the initial random numbers of the phase spectrum, and synthesizing sine waves that obtain an acceleration time history waveform by performing an inverse Fourier transform on the calculated complex Fourier coefficients. The method for generating simulated earthquake motion includes a fourth step S104 of calculating a time function that obtains an acceleration time history waveform of a candidate simulated earthquake motion by multiplying the acceleration time history waveform by an envelope function 4. The method for generating simulated earthquake motion includes a fifth step S105 of calculating a response spectrum that performs a response spectrum analysis on the acceleration time history waveform of the candidate simulated earthquake motion and calculates a response spectrum 7 of the candidate simulated earthquake motion. The method for creating simulated earthquake motion includes a sixth step S106 of determining whether the response spectrum 7 of the candidate simulated earthquake motion satisfies the allowable value of the response spectrum error of the candidate simulated earthquake motion with respect to the target spectrum 5 and is equal to or less than the excitation limit spectrum 6, and determining whether the response spectrum 7 satisfies the test condition for the target spectrum 5 and is equal to or less than the excitation limit spectrum 6. The method for creating simulated earthquake motion includes a seventh step S107 of adopting the candidate simulated earthquake motion as the simulated earthquake motion and writing output data Da2 if the response spectrum 7 of the candidate simulated earthquake motion satisfies the determination condition of the sixth step S106. The method for creating simulated earthquake motion includes an eighth step S108 of determining whether the number of trials i has reached the allowable number of corrections N of the Fourier amplitude if the response spectrum 7 of the candidate simulated earthquake motion does not satisfy the determination condition of the sixth step S106. The method for creating simulated earthquake motion includes a ninth step S109 of correcting the Fourier amplitude if the number of trials i has not reached the allowable number of corrections N of the Fourier amplitude. The method for generating simulated earthquake motions includes a tenth step S110 in which, after correcting the Fourier amplitudes, the number of trials i is incremented by 1 and the process returns to the third step S103 in which candidate simulated earthquake motions are generated using the corrected Fourier amplitudes.The method for creating simulated earthquake motion includes an eleventh step S110 in which it is determined that the study of creating simulated earthquake motion using the initial random number of the phase spectrum has diverged when the number of trials i reaches the allowable number of corrections N of the Fourier amplitude. Following the eleventh step S110, the method for creating simulated earthquake motion includes a twelfth step S112 in which the initial random number of the phase spectrum is changed to a different value to update the initial random number, and then the method returns to the third step S103 in which the acceleration time history waveform is obtained based on the updated initial random number.

[0066] According to this configuration, in the sixth step S106 of creating the simulated earthquake motion, by also verifying that the target spectrum 5 does not exceed the excitation limit spectrum 6 of the excitation device, it is possible to verify the target spectrum 5 and efficiently create simulated earthquake motion that falls within the excitation limit range of the excitation device.

[0067] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0068] 1...Simulated earthquake motion creation device, 2...Input display section, 4...Envelope function, 5...Target spectrum, 6...Excitation limit spectrum, 7...Response spectrum of simulated earthquake motion, 8...Time history waveform, 9...Excitation limit spectrum setting screen, 10...Excitation limit spectrum input method selection button, 11...Response spectrum frequency axis display condition setting button, 12...Response spectrum amplitude display condition setting button, 13...Excitation limit spectrum input table, 14...Simulated earthquake motion creation result display screen, 15...Summary of simulated earthquake motion creation results, 101...Memory section, 102...Calculation section.

Claims

1. A method for creating candidate simulated earthquake motions based on creation conditions and verifying the created candidate simulated earthquake motions, The values ​​used in the test are: a tolerance for response spectrum error expressed as a tolerance for the ratio of the amplitude of the response spectrum of the candidate simulated earthquake motion to the amplitude of the target spectrum, and a vibration limit spectrum of a vibration device are set; calculating a spectrum exceedance ratio obtained as an amplitude ratio of the response spectrum of the candidate simulated earthquake motion to the excitation limit spectrum; The test is a determination as to whether or not the result of generating the candidate simulated earthquake motion satisfies the test conditions that the amplitude ratio of the response spectrum of the candidate simulated earthquake motion to the amplitude of the target spectrum satisfies the tolerance for response spectrum error, and the candidate simulated earthquake motion is equal to or smaller than the excitation limit spectrum, if the amplitude ratio of the response spectrum of the candidate simulated earthquake motion to the amplitude of the target spectrum does not satisfy the tolerance for response spectrum error, correcting the creation conditions of the candidate simulated earthquake motion by multiplying the Fourier amplitude spectrum by the ratio of the target spectrum to the response spectrum of the candidate simulated earthquake motion; If the candidate simulated earthquake motion exceeds the excitation limit spectrum, correcting the creation conditions of the candidate simulated earthquake motion by multiplying the Fourier amplitude spectrum by the inverse of the spectral excess ratio in a frequency range in which the spectral excess ratio exceeds 1; The candidate simulated earthquake motion is again created based on the corrected creation conditions, and the verification is performed. If the created candidate simulated earthquake motion satisfies the verification conditions, the candidate simulated earthquake motion is acquired as the simulated earthquake motion. How to create simulated earthquake motion.

2. A method for creating simulated earthquake motion according to claim 1, comprising: creating the candidate simulated earthquake motions by setting an initial random number of the phase spectrum and an allowable number of corrections of the Fourier amplitude spectrum as the creation conditions of the simulated earthquake motions; If the result of generating the candidate simulated earthquake motion does not satisfy the test condition within the permissible number of corrections of the Fourier amplitude spectrum, the initial random number of the phase spectrum is updated and the candidate simulated earthquake motion is generated again. How to create simulated earthquake motion.

3. A method for creating simulated earthquake motion according to claim 1, comprising: In the step of setting values ​​to be used in the verification of the candidate simulated earthquake motions, calculating a target / excitation limit spectrum ratio as the amplitude of the target spectrum relative to the amplitude of the excitation limit spectrum; When the product of the target / excitation limit spectrum ratio and the tolerance of the response spectrum error is equal to or greater than 1 and exceeds the excitation limit spectrum of the vibration device, a correction method for re-registering the input data of the target spectrum; a correction method for removing the amplitude of the target spectrum; A method of correcting the vibration limit spectrum; Present How to create simulated earthquake motion.

4. A method for creating simulated earthquake motion according to claim 3, comprising: If a correction method for removing the amplitude of the target spectrum is specified, A range for removing amplitude is designated, and the target spectrum is calculated by removing the amplitude components in the designated range. When a correction method is specified by the excitation limit spectrum, For components in a frequency range exceeding the excitation limit spectrum of the vibration device, the amplitude of the target spectrum is corrected as a value obtained by subtracting the tolerance for the response spectrum error from the excitation limit spectrum. How to create simulated earthquake motion.

5. A method for creating simulated earthquake motion according to claim 1, comprising: The data of the vibration excitation device in which the vibration limit spectrum is set in advance and the vibration limit conditions of the vibration excitation device are selected from a database. How to create simulated earthquake motion.

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