Method, device, system, and program for calculating the time offset of multiple seismometers

Abstract

To provide a calculation method, a calculation apparatus, a calculation system, and a program for a time deviation amount between multiple seismometers that can calculate the time deviation amount between the multiple seismometers with high accuracy without sequential calculation, and use the calculated time deviation amount for correction of time deviation.SOLUTION: A method for calculating a time deviation amount of multiple seismometers 15 mounted in a building 10 includes: a step A of calculating a transfer function based on measurement data measured by the multiple seismometers 15; and a step B of calculating an inclination of a phase spectrum in a low frequency band in which the building 10 does not resonate, and calculating the time deviation amount by the following formula (X) based on the inclination of the phase spectrum.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method, a calculation device, a calculation system, and a program for calculating the amount of time offset between multiple seismometers. [Background technology]

[0002] When installing seismometers such as acceleration sensors on the first and upper floors of a multi-story building and calculating the deformation of the building from the measurement data taken during an earthquake, it is desirable to connect the seismometers on the first and upper floors with a wire and synchronize the time on both seismometers.However, connecting seismometers across floors with a wire has issues such as the complexity of the connection work, the inability to quickly respond to changes in installation location, and wiring limitations.

[0003] On the other hand, by connecting seismometers wirelessly, the disadvantages of wired connections are eliminated, but this creates another problem: the time on the seismometers cannot be synchronized, making it impossible to correctly calculate the deformation of each floor of the building at the same time.

[0004] Patent Document 1 proposes an analysis method that can correct for any discrepancy in the time measurements of two seismometers to accurately calculate inter-story displacement. Specifically, the method uses first acceleration data in the X-axis, Y-axis, and Z-axis directions along a time history obtained from a first residential seismometer installed near the first floor or in the foundation below the floor of a wooden building to measure acceleration due to earthquake shaking, and second acceleration data in the X-axis, Y-axis, and Z-axis directions along a time history obtained from a second residential seismometer installed near the first floor ceiling or near the second floor of the wooden building to measure acceleration due to earthquake shaking, and calculates at least the inter-story displacement when the wooden building is shaken using a predetermined analysis processing program. The correlation coefficient is calculated between the first acceleration data in the Z-axis direction from the first residential seismometer and the second acceleration data in the Z-axis direction from the second residential seismometer, and the time history discrepancy between the first acceleration data and the second acceleration data is corrected based on the calculation result, before calculating the inter-story displacement. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-100875 Summary of the Invention [Problem to be solved by the invention]

[0006] The analysis method described in Patent Document 1 calculates a correlation coefficient while gradually shifting the time of vertical acceleration waveforms measured by multiple seismometers, and determines the time shift amount when the correlation coefficient is maximum as the actual time shift amount. Therefore, calculating the correlation coefficient over the entire frequency band results in a problem of high noise and low accuracy, which is particularly noticeable on the high frequency side. Another problem is that the need to shift the time gradually and perform calculations sequentially results in a huge amount of calculation.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a method, a calculation device, a calculation system, and a program for calculating the time offset of multiple seismometers, which makes it possible to calculate the time offset of multiple seismometers with high accuracy while eliminating the need for sequential calculations, and to use the calculated time offset for time offset correction. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the method for calculating the time offset of a plurality of seismometers according to the present invention comprises: A method for calculating the amount of time offset between multiple seismometers installed in a building, comprising: Step A: calculating a transfer function based on measurement data measured by a plurality of the seismometers; and step B of calculating the slope of the phase spectrum in a low frequency band in which the building does not resonate, and calculating the time offset amount based on the slope of the phase spectrum using the following formula (X).

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[0009] According to this aspect, the transfer function is calculated based on measurement data measured by multiple seismometers, the slope of the phase spectrum in the low-frequency band where the building does not resonate is calculated, and the time offset between the multiple seismometers is calculated based on the slope of the phase spectrum, thereby making it possible to calculate the time offset between the multiple seismometers with high accuracy without requiring sequential calculations. Here, "multiple seismometers" refers to, for example, when two or three or more seismometers are installed on the first floor (or foundation floor) and the second or higher floors, the seismometer on the first or foundation floor that measures ground vibration input to the building, and any one of the seismometers on the second or higher floors, and includes combinations such as seismometers on the first and second floors, seismometers on the first and third floors, and seismometers on the first floor and rooftop floor (RF).

[0010] Furthermore, "low frequency bands in which buildings do not resonate" refers to frequency bands in which a multi-story building as a whole behaves in a translational manner, or frequency bands in which the response is not amplified; for example, if all floors behave in a translational manner, the phase difference between seismometers on multiple floors will be zero.

[0011] The transfer function (phase) is a function of the ratio of response to input: response / input. For example, when measurement data from a seismometer on the first floor is used as input data related to ground vibration, and measurement data from a seismometer on an upper floor is used as response data for that floor, taking into consideration that in the low frequency band where the building does not resonate, the phase difference between seismometers on multiple floors is zero as mentioned above, the phase of the transfer function will be -ωΔt if there is a time lag: Δt in the waveforms (sinusoidal waveforms, for example) of the seismometers on multiple floors. In formula (X), the amount of time lag can be calculated using the phases φ1, φ2 of any two frequencies f1, f2 and the angular frequencies ω1, ω2.

[0012] Another aspect of the method for calculating the time offset of a plurality of seismometers according to the present invention is to In the setting of the low frequency band, The upper limit of the low frequency band is set to f0 / 2 in consideration of the plastic region, where f0 is the primary natural frequency during structural calculation of the building. The lower limit of the low frequency band is 0.5 Hz.

[0013] According to this aspect, by quantitatively setting the upper and lower limits of the low frequency band, it is possible to clarify the frequency band to which formula (X) can be applied.

[0014] Here, the basis for setting the upper limit is that the inter-story deformation angle in the elastic region during a normal earthquake is generally set to about 1 / 200, and the inter-story deformation angle in the plastic region during a large-scale earthquake is set to about 1 / 100 to 1 / 75. Based on this, the plastic region is about half the elastic region, and the upper limit for the low frequency band is set to half the primary natural frequency: f0.

[0015] On the other hand, the basis for setting the lower limit is 0.5 Hz based on the performance (resolution) of seismometers currently in general use. In other words, since the lower limit can vary depending on the performance of the seismometer, it was decided to set it here based on the performance of general seismometers currently in use.

[0016] Furthermore, one aspect of the apparatus for calculating the time offset of a plurality of seismometers according to the present invention is A device for calculating the amount of time offset between multiple seismometers mounted on a building, comprising: It has a calculation department, In the calculation unit, Calculating a transfer function based on measurement data measured by the plurality of seismometers; Calculating the slope of the phase spectrum in a low frequency band where the building does not resonate; The time offset is calculated based on the gradient of the phase spectrum using the following formula (X):

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[0017] According to this aspect, the calculation unit calculates a transfer function based on measurement data measured by multiple seismometers, calculates the slope of the phase spectrum in the low frequency band where the building does not resonate, and calculates the time offset of the multiple seismometers based on the slope of the phase spectrum, thereby making it possible to calculate the time offset of the multiple seismometers with high accuracy while eliminating the need for sequential calculations.

[0018] Furthermore, one aspect of the system for calculating the time offset of a plurality of seismometers according to the present invention is The building includes a plurality of seismometers and the calculation device, The measurement data measured by the seismometer is received by the calculation device.

[0019] According to this aspect, measurement data measured by a plurality of seismometers is transmitted by wireless communication or the like to a calculation device located in a related department of the head office or branch office of the house manufacturer or construction company that constructed the building, and the calculation device that receives the measurement data quickly calculates the time offset of the target building, corrects the time offset of the plurality of seismometers (synchronizes the time) based on the calculated time offset, and then calculates the deformation and inter-story deformation angle of the building with high accuracy. Here, the measurement data can be received by the calculation device by wireless communication over a network, or by a method in which a resident of the target building or a person in charge at the house manufacturer obtains the measurement data and inputs it into the calculation device.

[0020] Furthermore, one aspect of the program according to the present invention is A program that causes a computer constituting a calculation device for calculating the amount of time offset of multiple seismometers installed in a building to execute the following processing: Calculating a transfer function based on measurement data measured by the plurality of seismometers; Calculating the slope of the phase spectrum in a low frequency band where the building does not resonate; The time offset is calculated based on the gradient of the phase spectrum using the following formula (X):

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[0021] According to this aspect, by having the computer constituting the time lag calculation device execute a predetermined process, it is possible to calculate the time lag of multiple seismometers with high accuracy while eliminating the need for sequential calculations. [Effects of the Invention]

[0022] As can be understood from the above explanation, the method, calculation device, calculation system, and program for calculating the time offset of multiple seismometers of the present invention can calculate the time offset of multiple seismometers with high accuracy while eliminating the need for sequential calculations, and the calculated time offset can be used to correct the time offset. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an overall configuration diagram showing an example of a system for calculating the amount of time offset between multiple seismometers according to an embodiment; [Figure 2] FIG. 2 is a diagram illustrating an example of a hardware configuration of a time lag calculation device according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of a functional configuration of a time lag calculation device according to an embodiment. [Figure 4] FIG. 10 is a diagram showing the relationship between frequency and phase spectrum in the case where there is no time lag, as measured in an experiment. [Figure 5] FIG. 10 is a diagram showing the relationship between frequency and phase spectrum in the case where there is a time lag (+0.5 s) measured in an experiment. [Figure 6] FIG. 10 is a diagram showing the relationship between frequency and phase spectrum in the case where there is a time lag (+2.0 seconds) measured in an experiment. [Figure 7] FIG. 10 is a diagram showing the relationship between frequency and phase spectrum in the case where there is a time lag (-3.0 s) measured in an experiment. [Figure 8] FIG. 10 is a graph showing the relationship between the phase spectrum gradient (phase gradient) and the time lag amount (time lag), which was created based on experimental results. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an example of a method, a calculation device, a calculation system, and a program for calculating the time offset of multiple seismometers according to an embodiment will be described with reference to the accompanying drawings. Note that in this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant explanation.

[0025] [Method, apparatus, system, and program for calculating the amount of time offset between multiple seismometers according to the embodiment] First, an example of a method, a calculation device, a calculation system, and a program for calculating the amount of time deviation between multiple seismometers according to an embodiment will be described with reference to Figures 1 to 3. Here, Figure 1 is an overall configuration diagram showing an example of a system for calculating the amount of time deviation between multiple seismometers according to an embodiment.

[0026] The time lag calculation system 50 includes a multi-story building 10 (two stories in the illustrated example) equipped with multiple seismometers 15 on each floor, and a calculation device 40 according to the embodiment located at a home builder 30 that constructed the building 10, with the seismometers 15 and the calculation device 40 being connected via a network 20 so that measurement data can be transmitted to the calculation device 40. The calculation system may also be configured such that a resident of the building 10 or a person in charge at the home builder obtains the measurement data and inputs it into the calculation device 40 without using the network 20, and such a configuration is also included in the calculation system.

[0027] In the illustrated example, a two-story building 10 has seismometers 15A and 15B mounted on the first and second floors, respectively. The building 10 vibrates due to earthquake motion E propagating through the ground G, and the resulting ground vibration is measured by seismometer 15A on the first floor, and the measured measurement data (acceleration data, for example, acceleration data on the X-axis, Y-axis, and Z-axis) is recorded. Meanwhile, the vibration of the building (response vibration) is measured by seismometer 15B on the second floor (upper floor), and similarly recorded as acceleration data. Both seismometers 15A and 15B are not time-synchronized via wires, and their respective measurement data are transmitted to calculation device 40 via network 20.

[0028] The network 20 includes a public network such as the Internet, a wireless network such as a mobile phone network, a dedicated network such as a VPN (Virtual Private Network), a LAN (Local Area Network), and the like.

[0029] Next, an example of the hardware configuration of the time lag calculation device 40 will be described with reference to FIG. 2, and an example of the functional configuration of the time lag calculation device 40 will be described with reference to FIG.

[0030] As shown in FIG. 2, the time lag calculation device 40 is configured by an information processing device (computer) such as a personal computer (PC).

[0031] The computer constituting the time lag calculation device 40 includes a CPU (Central Processing Unit) 41, a main memory device 42, an auxiliary memory device 43, an input / output IF (interface) 44, and a communication IF 45, which are interconnected by a connection bus 46. The main memory device 42 and the auxiliary memory device 43 are computer-readable recording media. Note that the above components may be provided separately, or some of the components may not be provided.

[0032] The CPU 41 is also called an MPU (Microprocessor) or a processor, and may be a single processor or a multiprocessor. The CPU 41 is a central processing unit that controls the entire computing device 40, which is a computer. The CPU 41, for example, deploys a program stored in the auxiliary storage device 43 in an executable form in the working area of ​​the main storage device 42, and controls peripheral devices through the execution of the program, thereby providing functions that meet a predetermined purpose.

[0033] The main memory device 42 stores computer programs executed by the CPU 41, data processed by the CPU 41, etc. The main memory device 42 includes, for example, a flash memory, a RAM (Random Access Memory), and a ROM (Read Only Memory). The auxiliary memory device 43 stores various programs and various data on a readable and writable recording medium, and is also called an external memory device. The auxiliary memory device 43 stores, for example, an OS (Operating System), various programs, various tables, etc. The OS includes, for example, a communication interface program that exchanges data with external devices connected via the communication IF 45. External devices for the calculation device 40 include the seismometer 15 and other computers in related departments (various structural calculation computers), etc.

[0034] The auxiliary storage device 43 is used, for example, as a storage area that supplements the main storage device 42, and stores computer programs executed by the CPU 41, data processed by the CPU 41, etc. The auxiliary storage device 43 is a silicon disk including nonvolatile semiconductor memory (flash memory, EPROM (Erasable Programmable ROM)), a hard disk drive (HDD: Hard Disk Drive), a solid state drive, etc. Examples of the auxiliary storage device 43 include drives for removable recording media such as CD drives, DVD drives, and BD drives, and examples of removable recording media include CDs, DVDs, BDs, USB (Universal Serial Bus) memories, and SD (Secure Digital) memory cards.

[0035] The input / output IF 44 is an interface for inputting and outputting data between devices connected to the calculation device 40. Input devices such as a keyboard, a touch panel, a mouse, or other pointing device, and a microphone are connected to the input / output IF 44. The calculation device 40 receives operation instructions and the like from an operator who operates the input device via the input / output IF 44.

[0036] In addition, output devices such as display devices, such as a liquid crystal display (LCD) panel or an electroluminescence (EL) panel, a printer, a speaker, etc. are connected to the input / output IF 44. The calculation device 40 displays the transfer function and the time difference between the two seismometers 15A and 15B.

[0037] The communication IF 45 is an interface with the network 20 to which the calculation device 40 is connected. The communication IF 45 transmits measurement data from the seismometer 15 to the calculation device 40 via various networks 20 including the above-mentioned public network such as the Internet.

[0038] 3, the calculation device 40 provides various functions of at least a communication unit 402, a calculation unit 404, and a storage unit 406 by executing a program by a CPU 41. Here, at least a part of the processing functions may be provided by a DSP (Digital Signal Processor), a GPU (Graphics Processing Unit), or the like, and similarly, at least a part of the processing functions may be provided by a dedicated LSI (Large Scale Integration) such as an FPGA (Field-Programmable Gate Array), a numerical calculation processor, an image processing processor, or other digital circuits.

[0039] After an earthquake occurs, the communication unit 402 receives the measurement data transmitted from each seismometer 15 for a certain period of time and stores the data in the storage unit 406 as needed.

[0040] The calculation unit 404 calculates the amount of time difference between the two seismometers 15A and 15B based on the measurement data.

[0041] Here, the building vibration (response) of building 10 measured by seismometer 15B on the second floor and the ground vibration (input) measured by seismometer 15A on the first floor can be expressed by the following equations (Y1) and (Y2), respectively.

[0042]

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[0043] From the equations (Y1) and (Y2), the transfer function (phase) can be expressed by the following equation (Y3).

[0044]

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[0045] In the low frequency band where building 10 does not resonate, the entire building 10 behaves in a translational manner, and the phase difference between the two seismometers 15A and 15B is zero, so β ​​= α.By substituting this into equation (Y3), the phase of the transfer function when there is a time lag can be expressed by the following equation (Y4).

[0046]

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[0047] To calculate the time offset, the phases are calculated in multiple frequency bands and a simultaneous equation is solved. That is, the phase offsets φ1 and φ2 of the two frequencies f1 and f2 can be expressed by the following equations (Z1) and (Z2).

[0048]

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[0049] From equations (Z1) and (Z2), the time lag Δt can be expressed by the following equation (X).

[0050]

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[0051] The calculation unit 404 executes step A, which calculates a transfer function based on the measurement data measured by the two seismometers 15A and 15B, calculates the slope of the phase spectrum in the low frequency band where the building 10 does not resonate, and executes step B, which calculates the time lag amount using equation (X) based on the slope of the phase spectrum. The calculated time lag amount Δt is stored in the storage unit 406. The series of processes in steps A and B by the calculation unit 404 constitutes the time lag calculation method according to the embodiment.

[0052] Here, the upper limit of the low frequency band is set to f0 / 2, taking into account the plastic region, with respect to the primary natural frequency: f0 during structural calculations for building 10, and the lower limit of the low frequency band is set to 0.5 Hz based on the performance of seismometers currently in common use.

[0053] In the calculation device 40, a program that causes a computer to execute the following processes is installed, and thereby the above-mentioned processes are executed in the calculation unit 404. That is, the process based on this program calculates a transfer function based on the measurement data measured by the seismometers 15A and 15B, calculates the slope of the phase spectrum in the low frequency band where the building 10 does not resonate, and calculates the amount of time difference between the seismometers 15A and 15B using the above formula (X) based on the slope of the phase spectrum.

[0054] The illustrated device, calculation system, and calculation method for calculating the time offset of a seismometer eliminate the need for sequential calculations and allow the time offset of multiple seismometers 15A, 15B to be calculated directly from the phase gradient obtained in a single calculation, for example, so that the time offset can be calculated easily and quickly.

[0055] Furthermore, since the time offset is calculated for the low frequency band, the influence of noise (error) is small, and the time offset can be calculated with high accuracy.

[0056] The calculation device 40 may further include a structural calculation unit (not shown), which corrects the time difference between the measurement data of the seismometers 15A and 15B based on the calculated time difference, and then calculates the deformation of the first and second floors during an earthquake based on both sets of time-synchronized measurement data, thereby calculating the inter-story deformation angle of the building 10. The safety level and the degree of damage of the building 10 can be evaluated based on the calculated inter-story deformation angle, etc.

[0057] [Experiment to verify the validity of the calculation formula for time lag] The inventors conducted an experiment to verify the validity of the above formula (X). In this experiment, based on the actual measurements of two seismometers, the relationship between frequency and phase spectrum was determined for four cases: no time lag, a time lag of +0.5 seconds, a time lag of +2 seconds, and a time lag of -3 seconds. Here, the ± time lag indicates that the seismometer on the first floor is used as the reference and that the seismometer on the second floor is delayed and has a time lag of +.

[0058] Figures 4, 5, 6, and 7 show the relationship between frequency and phase spectrum in the cases of no time lag, time lag (+0.5 s), time lag (+2.0 s), and time lag (-3.0 s), respectively, as measured in the experiment. Also, Figure 8 shows a graph of the relationship between the slope of the phase spectrum (phase slope) and the amount of time lag (time lag), created based on the experimental results.

[0059] Figure 4 demonstrates that in the case of no time lag, the phase spectrum slope is zero in the frequency band below 3 Hz, and that as the frequency increases, the phase spectrum becomes more randomly dispersed.

[0060] Furthermore, when comparing the gradients of the phase spectrum in the low frequency band (for example, 0.5 to 1 Hz) in FIGS. 5 to 7, it is demonstrated that the gradient of the phase spectrum increases as the amount of time lag increases.

[0061] The slope of the phase spectrum at each time shift can be calculated by a method of finding an approximate line, which is one of statistical processing, or by using the median of multiple values ​​found by moving average.

[0062] Summarizing the results of these experiments, the relationship between the phase gradient and the time lag can be expressed by the approximate straight line shown in FIG. 8, which coincides with the above-mentioned formula (X).

[0063] In this way, in the low-frequency band where the influence of buildings does not need to be considered, if there is no time lag between the two seismometers, the phase gradient is zero, but if there is a time lag, the phase will have a gradient. By calculating this gradient using a formula, it is possible to calculate the amount of time lag easily and quickly, eliminating the need for sequential calculations.

[0064] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0065] 10: Building (2-story building) 15,15A,15B: Seismograph 20: Network 30: House builder 40: Calculation device (time deviation calculation device) 50: Calculation system (time deviation calculation system) 402: Communications Department 404: Calculation Department 406: Storage area G: Ground E: Earthquake motion

Claims

1. A method for calculating the amount of time offset between multiple seismometers installed in a building, comprising: Step A: based on measurement data measured by the plurality of seismometers, calculating a transfer function, which is the ratio of response to input when measurement data measured by the seismometer on the first floor is used as input data related to ground vibration and measurement data measured by the seismometer on an upper floor is used as response data for the upper floor; and step B of calculating the slope of the phase spectrum in a low frequency band in which the building does not resonate, and calculating the time offset based on the slope of the phase spectrum using the following formula (X): [Equation 1]

2. In the setting of the low frequency band, The upper limit of the low frequency band is the primary natural frequency: f ０ Considering the plastic region, ０ / 2, 2. The method for calculating the time offset of a plurality of seismometers according to claim 1, wherein the lower limit of the low frequency band is 0.5 Hz.

3. A device for calculating the amount of time offset between multiple seismometers mounted on a building, comprising: It has a calculation department, In the calculation unit, Based on the measurement data measured by the plurality of seismometers, a transfer function is calculated, which is the ratio of the response to the input when the measurement data from the seismometer on the first floor is used as input data related to ground vibration and the measurement data from the seismometer on the upper floor is used as response data for the upper floor; Calculating the slope of the phase spectrum in a low frequency band where the building does not resonate; A device for calculating the amount of time deviation of a plurality of seismometers, characterized in that the device calculates the amount of time deviation based on the slope of the phase spectrum using the following formula (X): [Equation 1]

4. a plurality of seismometers provided in the building; and the calculation device according to claim 3; A system for calculating the amount of time offset between a plurality of seismometers, characterized in that the system is configured so that measurement data measured by the seismometers is received by the calculation device.

5. A program that causes a computer constituting a calculation device for calculating the amount of time offset of multiple seismometers mounted on a building to execute the following processing: Based on the measurement data measured by the plurality of seismometers, a transfer function is calculated, which is the ratio of the response to the input when the measurement data from the seismometer on the first floor is used as input data related to ground vibration and the measurement data from the seismometer on the upper floor is used as response data for the upper floor; Calculating the slope of the phase spectrum in a low frequency band where the building does not resonate; Calculating the time lag amount based on the slope of the phase spectrum using the following formula (X): [Equation 1]

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