JP2021139853A - Judgment method and judgment device for continuous usability after an earthquake - Google Patents

Abstract

To provide a method and device for determining continuous usability after earthquakes in a building in a case where a plurality of earthquakes occurs in a relatively short period.SOLUTION: A device 10 for determining the continuous usability of a building 12 after an earthquake, comprises: acquisition means 16 of acquiring time waveform data indicating earthquake motion by an earthquake sensor 14 provided in the building 12; calculation means 18 of calculating the energy of the earthquake motion with respect to the building 12 based on the acquired time waveform data; comparison means 20 of comparing the calculated energy of the earthquake motion with the energy absorption capacity of the building 12; and determination means 22 of determining continuous usability after the earthquake based on the result of comparison.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method and a determination device for determining continuous usability after an earthquake in a building.

In recent years, social perceptions of large earthquakes have been changing. In the 2011 off the Pacific coast of East Japan Earthquake (March 11, 2011), six large aftershocks of M7 or larger occurred within about three months after the mainshock of magnitude (M) 9. In the 2016 Kumamoto earthquake, two huge earthquakes of the same level occurred in less than 28 hours. Government agencies have reported that the Tokai, Tonankai, and Nankai earthquakes, which are imminent, may have a series of huge earthquakes within hours to months.

On the other hand, as papers on the seismic design of conventional buildings and their behavior during earthquakes, for example, those described in Non-Patent Documents 1 to 5 are known.

Hiroshi Akiyama: Seismic Design of Buildings Based on Energy Balance, Gihodo, 1999.11. Kensuke Shimizu, Yuhei Chiba, Takayuki Teramoto: Study on the behavior of S-structured buildings during the Hyogo-ken Nanbu Earthquake-Part 3-, Architectural Institute of Japan Academic Lecture Abstracts, pp.871-872, 2007.9 Takashi Ishida, Soichi Toriyama, Mitsuru Eguchi, Kazumasa Soga, Tadashi Tamura, Kazuya Ota, Kazuo Murakami, Haruyuki Kitamura: Seismic evaluation method based on energy balance of thermal power plant buildings with partial historical dampers in the lower layer, Japan Architectural Institute of Japan Structural Engineering Proceedings Vol.64B, pp.215-224, 2018.3. Haruyuki Kitamura, Takayuki Teramoto, Kunio Ukai, Katsuhide Murakami, Hiroshi Akiyama, Akira Wada: Study on Damage to Buildings in the Hyogoken Nanbu Earthquake, Architectural Institute of Japan Structural Papers No. 503, pp.165-170, 1998.1. Yukihiro Takenotani, Yuichiro Ishinabe, Toshio Hannuki, Hiroshi Akiyama: Examination of the effects of aftershocks on building structures, Proceedings of the Japan Association for Earthquake Engineering Vol. 12, No. 4, pp.127-142, 2012

As mentioned above, there is concern that multiple large earthquakes may strike in a relatively short period of time, and there is a social need to confirm the seismic safety of buildings against them or to judge their continuous usability after an earthquake. .. However, in conventional seismic designs, it is customary to verify seismic safety for one wave of the mainshock. In addition, a method for evaluating seismic resistance against aftershocks that occur many times after the mainshock has not been established.

The present invention has been made in view of the above, and an object of the present invention is to provide a method and a determination device for determining the continuous usability of a building after an earthquake when a plurality of earthquakes strike in a relatively short period of time. ..

In order to solve the above-mentioned problems and achieve the object, the method for determining the continuous usability after an earthquake according to the present invention is a method for determining the continuous usability of a building after an earthquake, which is an earthquake provided in the building. The step of acquiring the time waveform data indicating the seismic motion by the sensor, the step of calculating the energy of the seismic motion for the building based on the acquired time waveform data, and comparing the calculated energy of the seismic motion with the energy absorption capacity of the building. It is characterized by including a step and a step of determining continuous usability after an earthquake based on the result of comparison.

Further, the device for determining the continuous usability after an earthquake according to the present invention is a device for determining the continuous usability of a building after an earthquake, and acquires time waveform data indicating seismic motion by an earthquake sensor provided in the building. Based on the results of comparison, the means, the calculation means for calculating the energy of the seismic motion with respect to the building based on the acquired time waveform data, and the comparison means for comparing the calculated energy of the seismic motion with the energy absorption capacity of the building. It is characterized in that it is provided with a determination means for determining continuous usability after an earthquake.

According to the method for determining the continuous usability after an earthquake according to the present invention, it is a method for determining the continuous usability of a building after an earthquake, and is a step of acquiring time waveform data indicating seismic motion by an earthquake sensor provided in the building. After the earthquake, based on the results of the step of calculating the seismic motion energy for the building based on the acquired time waveform data, the step of comparing the calculated seismic motion energy with the energy absorption capacity of the building, and the comparison result. Since it is provided with a step of determining the continuous usability of the building, it is possible to determine the continuous usability of the building after the earthquake when a plurality of earthquakes strike in a relatively short period of time. Further, according to the method for determining the continuous usability after an earthquake according to the present invention, the continuous usability of the building is determined not only for the observed seismic motion but also for the assumed seismic motion (for example, the seismic motion for designing a notification wave or the like). Can be evaluated.

Further, according to the device for determining the continuous usability after an earthquake according to the present invention, it is a device for determining the continuous usability of a building after an earthquake, and time waveform data indicating the seismic motion is acquired by an earthquake sensor provided in the building. The result of comparison is the acquisition means to be performed, the calculation means to calculate the energy of the seismic motion with respect to the building based on the acquired time waveform data, and the comparison means to compare the calculated energy of the seismic motion with the energy absorption capacity of the building. Based on this, since it is provided with a determination means for determining the continuous usability after an earthquake, it is possible to determine the continuous usability of a building after an earthquake when a plurality of earthquakes strike in a relatively short period of time. .. Further, according to the device for determining the continuous usability after an earthquake according to the present invention, the continuous usability of the building can be determined not only for the observed seismic motion but also for the assumed seismic motion (for example, the seismic motion for designing a notification wave or the like). Can be evaluated.

FIG. 1 is a diagram showing an embodiment of a device for determining continuous usability after an earthquake according to the present invention. FIG. 2 is a diagram showing the relationship between the energy spectra of the mainshock 1 and the aftershock 2 and the cumulative energy spectrum of the seismic motion in which the aftershock 2 is connected after the mainshock 1. FIG. 3 is a diagram showing a procedure for calculating _{the energy absorption amount (E i} ) and the cumulative plastic deformation ratio (η _i ) of each layer with respect to an earthquake. FIG. 4 is a table diagram showing the relationship between the maximum plasticity ratio of the layer and the cumulative plastic deformation ratio corresponding to the degree of damage to the building. FIG. 5 is a table diagram showing criteria (provisional plan) for determining continuous usability after an earthquake.

The present invention is, for example, a practical method useful for determining continuous usability after an earthquake in consideration of aftershocks in addition to the mainshock, mainly for steel-framed buildings (including vibration damping structures with dampers). Hereinafter, a method for determining continuous usability after an earthquake and an embodiment of the determination device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

As shown in FIG. 1, the determination device 10 for continuous usability after an earthquake of the present embodiment includes an acquisition means 16 for acquiring time waveform data indicating seismic motion by an accelerometer 14 (earthquake sensor) provided in the building 12. Based on the acquired time waveform data, the calculation means 18 that calculates the energy of the seismic motion with respect to the building 12 and the comparison means 20 that compares the calculated energy of the seismic motion with the energy absorption capacity of the building 12 are compared. Based on this, a determination means 22 for determining continuous usability after an earthquake is provided.

The accelerometer 14 is installed in advance on the first floor of the building 12 or at several locations at the base, and measures the time waveform data observed at the time of an earthquake. The acquisition means 16 can be configured by a recording device such as a data logger that records time waveform data. The calculation means 18, the comparison means 20, and the determination means 22 can be configured by using, for example, a calculation function provided in a computer. The determination result or the like is output to an output means such as a monitor or a printer (not shown). In the present embodiment, the energy input of the seismic motion to the building 12 is calculated from the time waveform data measured by the accelerometer 14, and compared with the energy absorption capacity of the building 12, the degree of damage (continuous usability) after the earthquake is determined. Judge early.

In particular, the present embodiment has the following three items.
1) Calculation method of energy input to the building due to the mainshock and aftershock 2) Calculation method of energy absorption capacity of the building 3) Judgment method of continuous usability based on the degree of damage to the building after the earthquake Each item will be explained below.

1) Calculation method of energy input to building (introduction of cumulative energy spectrum)
If the structure of the building is in an elastic state, the primary natural period can be regarded as a _{constant value (T 0).} In such an elastic vibration system, it is assumed that the seismic motion 1 is the mainshock and the subsequent seismic motion i (i is an integer of 2 or more) is an aftershock. FIG. 2 shows the relationship between the energy spectra of the mainshock and the aftershock and the cumulative energy spectrum of the seismic motion in which the aftershock is connected after the mainshock. In the figure, ACC is the measured acceleration value, _VE1 (T) is the energy spectrum of the mainshock 1, and _VE2 (T) is the energy spectrum of the aftershock 2.

The total energy input of the seismic motion (hereinafter referred to as the cumulative total energy input) in which the aftershocks are connected after the mainshock is the sum of the total energy input of each seismic motion as shown in Eq. (1). The velocity conversion value of the cumulative total energy input (hereinafter referred to as the cumulative velocity conversion value) is the sum of squares of the velocity conversion values of each seismic motion, and is given by Eq. (2). According to FIG. 2, the accumulated speed converted value _{(S V E)} corresponds to the numerical value of the ordinate of the cumulative energy spectrum corresponding to the natural period of a building (T _0).

Here, _{S E:} main shock following the aftershocks i (2 ≦ i ≦ n) seismic motion of the cumulative total energy input which is connected to the 1
E _i : Total energy input of mainshock 1 and aftershock i (2 ≤ i ≤ n)
_S V _E: main shock following the aftershocks i (2 ≦ i ≦ n) seismic motion of the cumulative rate conversion value obtained by connecting the _{1 (S V E = SQRT (} 2 S E / M))
V _Ei : Velocity conversion value of mainshock 1 and aftershock i (2 ≦ i ≦ n) ( _VEi = SQRT (2E _i / M))
M: Total mass of the building
n: Total number of mainshocks and aftershocks

Since the actual building suffers some damage during a large earthquake, it becomes elasto-plastic after the earthquake. If the up wave dissipating the affected degree to allow continued use of after the earthquake a building, the period of the state in which the building is slightly plasticized (hereinafter, referred to as the effective period T _e) is elastic at the period (T ₀₎ It is considered that there is not much difference compared to. Valid period when restoring force characteristics of the layers are completely elasto-plastic type (T _e) is approximated evaluated by the average of the elastic time period (T ₀₎ and the maximum instantaneous period (T _m) (see Non-Patent Document 1 ), (3) and (4). According to Non-Patent Document 2, the maximum plasticity rate of the layer in which the degree of damage to the building is small is 1.5 or less, and from this and Eq. (4), T _m ≈ 1.2 _{T 0.} effective period corresponding to fracture the _{(T e)} and _{T 0 ≦ T e ≦ 1.2T 0} .

Here, T ₀ : elastic primary natural period
T _m : Cycle required to draw a history loop corresponding to the maximum deformation during an earthquake (called the instantaneous maximum cycle)
μ: Plasticity ratio

From the above, the cumulative rate conversion value obtained by adding aftershock to main shock _{(S V E)} is accumulated energy spectrum in the range effective period is _{T 0} ≦ _{T e} ≦ 1.2T ₀ as indicated by (5) Give at the maximum value of.

_{Here, T 0 ≦ T e ≦ 1.2T} 0: effective period of up wave dissipating from undamaged range

2) Method for calculating the energy absorption capacity of a building As a method for calculating the energy absorption amount of each layer, the method described in Non-Patent Document 3 constructed by the present inventors is used.
FIG. 3 shows a procedure for calculating the amount of energy absorbed by each layer against an earthquake. As shown in this figure, the main structure is modeled into a three-dimensional or two-dimensional frame in advance with reference to the structural calculation sheet, structural drawing, etc. of the building, and static incremental analysis is performed using the horizontal force during an earthquake as the acting external force. (Step S11). From the result, the relationship (Q _{i −} δ _i relationship) between the layer shear force (Q _i ) and the interlayer displacement (δ _i ) of each layer is set (step S12). Layer having the damper, respectively bilinear the Q _i - [delta _i relation main Frames and damper portion (step S13). On the other hand, no damper layer, the bilinear the _Q i - [delta _i relationship entire Frame (step S14).

Subsequently, the interlayer displacement distribution in the load step of the static incremental analysis _{is assumed to be the maximum interlayer displacement (δ mi} ) (step S15), and the energy distribution amount (E _{i) of each layer is used using the bilinear Q i −} δ _{i relationship.} ) (See Step S16, Non-Patent Document 3 for the calculation method).

On the other hand, the above-mentioned 1) according to calculate the cumulative energy spectrum (step S21), and calculates the cumulative rate converted value _{(S V E)} (step S22), and input energy _{(E D} to contribute building building damage ) Is calculated (step S23).

Next, compare the calculated _{E D} and? En _i, if the energy balance _{(E D} ≒ ΣE _i) is not satisfied assuming [delta] _mi again, repeating until the amount of energy _{E D} and? En _i are balanced Convergence calculation is performed (step S17). As a result of convergence, E _{i of} each layer is calculated (step S18), and the cumulative plastic deformation ratio (η _i ) is obtained from this (step S19).

3) Method for determining continuous usability based on the degree of damage to buildings after the earthquake According to Non-Patent Documents 2 and 4, the degree of damage and the cumulative plastic deformation ratio of layers (η _i ) for buildings damaged by the Hyogo-ken Nanbu Earthquake. Is associated with each other as shown in FIG.

In the present embodiment, the degree of damage that allows the continuous usability of the building after the earthquake is defined as from no damage to small damage, and the damage level above medium damage is defined as unusable. With reference to the above-mentioned Non-Patent Documents 2 and 4, the cumulative plastic deformation ratio of the layer corresponding to the boundary between the small break and the medium break is about 10, so the criterion for determining the continuous usability is as shown in FIG. 5, for example. Can be set. The table in this figure is a tentative plan and will be reviewed in actual operation.

For example, if the maximum value of the cumulative plastic deformation ratio (η _i ) of each layer calculated in 2) above is less than 10, it is judged from FIG. Can be done.

According to this embodiment, it is possible to determine the degree of damage not only after the mainshock but also after aftershocks that occur several times. Therefore, it is possible to determine the continuous usability of a building after an earthquake when a plurality of earthquakes strike in a relatively short period of time. It is also useful for evaluating seismic resistance against aftershocks not only after an earthquake but also in advance. The evaluation results will serve as materials that contribute to the business continuity plan (BCP). In addition, it is possible to determine the degree of damage at an early stage by omitting the work of grasping the damaged state of the building (decrease in rigidity and horizontal strength with respect to the initial state, etc.) after each earthquake. In addition, accelerometers do not necessarily have to be installed on each floor, and there is a possibility that a cost advantage can be obtained as compared with a generally practical monitoring system.

In the above embodiment, the case where the seismic sensor is composed of an accelerometer has been described as an example, but the seismic sensor of the present invention is not limited to this, and seismic motion is detected by using a displacement meter or a speedometer. The indicated time waveform data may be acquired. Even in this way, the same effect as described above can be obtained.

Further, in the above-described embodiment, the case of evaluating the continuous usability of the building from the time waveform data observed at the time of an earthquake has been described as an example, but the present invention is not limited to this. That is, the present invention can evaluate the continuous usability of a building not only for observed ground motion but also for assumed ground motion (for example, design ground motion such as notification wave).

As described above, according to the method for determining the continuous usability after an earthquake according to the present invention, it is a method for determining the continuous usability of a building after an earthquake, and the time for indicating the seismic motion by an earthquake sensor provided in the building. Results of comparison between the step of acquiring waveform data, the step of calculating the energy of seismic motion for a building based on the acquired time waveform data, and the step of comparing the calculated energy of seismic motion with the energy absorption capacity of a building. Since the step of determining the continuous usability after the earthquake is provided based on the above, it is possible to determine the continuous usability of the building after the earthquake when a plurality of earthquakes hit in a relatively short period of time. Further, according to the method for determining the continuous usability after an earthquake according to the present invention, the continuous usability of the building is determined not only for the observed seismic motion but also for the assumed seismic motion (for example, the seismic motion for designing a notification wave or the like). Can be evaluated.

Further, according to the device for determining the continuous usability after an earthquake according to the present invention, it is a device for determining the continuous usability of a building after an earthquake, and time waveform data indicating the seismic motion is acquired by an earthquake sensor provided in the building. The result of comparison is the acquisition means to be performed, the calculation means to calculate the energy of the seismic motion with respect to the building based on the acquired time waveform data, and the comparison means to compare the calculated energy of the seismic motion with the energy absorption capacity of the building. Based on this, since it is provided with a determination means for determining the continuous usability after an earthquake, it is possible to determine the continuous usability of a building after an earthquake when a plurality of earthquakes strike in a relatively short period of time. Further, according to the device for determining the continuous usability after an earthquake according to the present invention, the continuous usability of the building can be determined not only for the observed seismic motion but also for the assumed seismic motion (for example, the seismic motion for designing a notification wave or the like). Can be evaluated.

As described above, the method and device for determining the continuous usability after an earthquake according to the present invention are useful for determining the continuous usability of a building, and in particular, a plurality of earthquakes struck in a relatively short period of time. Suitable for determining continuous usability in cases.

10 Judgment device for continuous usability after an earthquake 12 Building 14 Accelerometer (earthquake sensor)
16 Acquisition means 18 Calculation means 20 Comparison means 22 Judgment means

Claims (2)

It is a method to judge the continuous usability of a building after an earthquake.
Steps to acquire time waveform data indicating seismic motion by seismic sensors installed in the building,
Steps to calculate the energy of seismic motion for a building based on the acquired time waveform data,
Steps to compare the calculated energy of seismic motion with the energy absorption capacity of the building,
A method for determining continuous usability after an earthquake, which comprises a step of determining continuous usability after an earthquake based on the results of comparison. A device that determines the continuous usability of a building after an earthquake.
An acquisition means for acquiring time waveform data indicating seismic motion using an earthquake sensor installed in a building,
A calculation method for calculating the energy of seismic motion against a building based on the acquired time waveform data,
A means of comparison between the calculated energy of seismic motion and the energy absorption capacity of a building,
A device for determining continuous usability after an earthquake, which comprises a determining means for determining continuous usability after an earthquake based on the results of comparison.

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