JP7369424B2 - Evaluation method and system for the useful life of buildings - Google Patents

Description

The present invention relates to a method and system for evaluating the useful life of a building.

Conventionally, the legal useful life has been known as the useful life of a building, which is used as the basis for calculating depreciation of fixed assets. This legal service life is determined uniformly for each classification by classifying buildings according to their structure and use. The legal service life, which was uniformly determined in this way, was used as the standard for evaluating the economic value of buildings.
No particular literature survey was conducted.

As mentioned above, the legal service life is determined uniformly for each type of building, and does not take into account the actual circumstances of each building. Therefore, any building that has passed its legal useful life is judged to have no economic value.
However, there are some buildings that have sufficient economic value even if their legal useful life reaches zero.

In this way, if the economic value of a building is denied based on its legal useful life, it may have a negative impact on economic revitalization.
In other words, the uniformly prescribed legal service life did not match the actual condition of buildings and was not appropriate as an indicator for evaluating the value of buildings.

An object of the present invention is to provide a method and system for evaluating the useful life of a building, which can be used as an index for evaluating the value of a building, and is suitable for the actual condition of a building.

The first invention is a method for evaluating the useful life of a building.
First, a gradual decreasing model D of the natural frequency that decreases over time in the building to be measured is created, and an equivalent model B of the building is created. Furthermore, the seismic limit value of the building is set, and the reference natural frequency fx exceeding the seismic limit value is specified using the equivalent model B of the building. Once the reference natural frequency fx is specified, the reference natural frequency fx is applied to the gradual decrease model D to specify the service life of the building.
The above-mentioned equivalent model B is a model that exhibits the same vibration characteristics as the building to be measured.

A second invention is such that the process of specifying the reference fixed frequency fx includes a process of specifying an assumed seismic waveform, a process of vibrating the equivalent model B based on the assumed seismic waveform, and a process of vibrating the equivalent model B based on the assumed seismic waveform. The process includes a process of specifying the amount of displacement, and a process of specifying the reference natural frequency fx based on the natural frequency when the specified amount of displacement exceeds the seismic limit value.

A third aspect of the present invention is that the process of identifying the reference natural frequency fx includes a process of identifying an assumed seismic waveform, and a process of identifying a plurality of estimated natural frequencies from the natural frequencies of the building at a specific time; A process of vibrating the equivalent model B for each of the plurality of estimated natural frequencies based on the assumed seismic waveform, and a process of specifying the amount of displacement of the equivalent model B based on each of the estimated natural frequencies. The method includes a process of setting the estimated natural frequency when the amount of displacement exceeds the seismic limit value as the reference natural frequency.

The estimated natural frequency is one in which the future is artificially estimated from the natural frequency at the specific point in time, for example, the current time. A plurality of such estimated natural frequencies are specified, and the identified plurality of estimated natural frequencies are sequentially input into the equivalent model B to specify the amount of displacement corresponding to the estimated natural frequencies. Note that how to identify the plurality of natural frequencies is determined artificially.
For example, if a person evaluates a building and determines that it will have sufficient strength in the future, the estimated natural frequency is set to a small value overall. On the other hand, when the strength cannot be expected, the estimated natural frequency is set to a large value overall. Another major feature of this invention is that it takes human evaluation into account.

The process of specifying the reference natural frequency fx of the fourth invention includes a process of specifying a plurality of assumed earthquake waveforms, a process of specifying a plurality of estimated natural frequencies from the natural frequency of the building at a specific time, A process of associating the plurality of estimated natural frequencies with each of the plurality of assumed seismic waveforms and vibrating the equivalent model B for each of the estimated natural frequencies; a process of identifying the amount of displacement of the equivalent model B based on the earthquake, and a process of identifying an estimated natural frequency at which the identified amount of displacement exceeds the seismic limit value as a comparison natural frequency for each of the assumed seismic waveforms, The method includes a process of comparing the comparison natural frequencies, and a process of specifying a reference natural frequency fx based on the comparison result.
Note that this comparison natural frequency is specified as one whose displacement exceeds the seismic limit value for each assumed earthquake waveform. The plurality of comparative natural frequencies thus specified are compared with each other, and the reference natural frequency fx is determined from these comparative natural frequencies.

Note that any method may be used to specify the reference natural frequency fx based on the comparison of comparative natural frequencies. For example, rules for this purpose may be set in advance, such as using the average value or median value, the maximum value, or the minimum value of a plurality of comparative natural frequencies. In short, any rule may be used as long as the optimal reference natural frequency can be found based on the type of building, location conditions, etc.
Based on these rules, for example, if the maximum value of multiple comparative natural frequencies is taken as the reference natural frequency fx, the service life of the building will be calculated to be relatively short, so it is necessary to evaluate it more strictly. become. On the other hand, if the minimum value of the comparison natural frequencies is taken as the reference natural frequency fx, the service life of the building will be underestimated.

The process of identifying the reference natural frequency fx of the fifth invention includes a process of identifying the elastic limit point of the building in the displacement-resistance correlation characteristic using the equivalent model B, and a process of identifying the elastic limit point of the building in the displacement -resistance correlation characteristic, and In the force correlation characteristics, a process of setting the seismic limit point of the building in a range of resistance below the elastic limit point, and a process of setting the natural frequency at the seismic limit point as the reference natural frequency fx. include.

In the sixth invention, based on the seismic limit value set by the arithmetic unit, the equivalent model B specifies a reference natural frequency fx that exceeds the seismic limit value. The service life of the building is calculated by applying this reference natural frequency fx to the gradual decrease model D of natural frequency.

A seventh invention is based on the sixth invention, and one or more assumed seismic waveforms are stored in the storage unit. For each of these assumed earthquake waveforms, a comparative natural frequency, which is a natural frequency that exceeds the seismic limit value, can be identified. Therefore, by identifying a plurality of assumed earthquake waveforms based on past earthquakes in the area where a building is located, it is possible to calculate the service life in consideration of regional characteristics.

An eighth invention is based on the sixth invention, and includes a function in which the calculation unit uses the equivalent model B to create a displacement-resistance correlation characteristic based on the natural frequency at the specific time; The function of identifying the elastic limit point in this displacement-resistance correlation characteristic, the function of setting the seismic limit value in the range of resistance below the elastic limit point, and the function of the displacement-resistance correlation characteristic are It also has a function of specifying the natural frequency that overlaps the limit point as the reference natural frequency fx.

A ninth invention provides a function for the calculation unit to create the gradually decreasing model D based on the natural frequency of the building at a specific point in time, which is input from the storage unit or the input unit, and the storage unit Alternatively, it has a function of creating the equivalent model B based on the height and mass of the building input from the input section and the natural frequency at the specific time point.

In this invention, the reference natural frequency corresponding to the seismic limit value can be specified using the equivalent model B of the building to be evaluated, and the service life can be specified from this reference natural frequency. The service life specified based on the natural frequency of a building is not fixed uniformly like the legal service life, but reflects the uniqueness of the building. Therefore, the service life of the present invention matches the actual condition of the building and can be used as an index for evaluating the value of the building.

FIG. 1 is a block diagram showing a device that operates the system of the first embodiment. It is a graph showing a gradual decrease model D of the natural frequency of the building in the first embodiment. It is a schematic diagram showing a building which is an evaluation target of a 1st embodiment. This is an equivalent model B of the building of the first embodiment. 7 is a graph showing the displacement-resistance force correlation characteristic of equivalent model B of the building in the second embodiment.

The first embodiment of the present invention shown in FIGS. 1 to 4 includes a calculation device 3 consisting of a calculation section 1 and a storage section 2, as shown in FIG. An input section 4 and an output section 5 are connected to this arithmetic device 3.

The calculation unit 1 has a function of creating the gradual decrease model D shown in FIG. 2 when the natural frequencies of at least two points at specific points having a time difference are input.
The two natural frequencies at the specific point in time are the first natural frequency at the specific point in time and the second natural frequency at another specific point with a time difference with respect to the specific point in time.

Note that the first natural frequency may be specified based on past records such as building specifications at the time of new construction, or the current natural frequency may be used as the first natural frequency. When the current natural frequency is set as the first natural frequency, it is necessary to separately measure a future natural frequency further beyond the current point and use it as the second natural frequency.

When the natural frequencies of the two points are input to the calculation unit 1 as described above, the calculation unit 1 creates a gradually decreasing model D consisting of a straight line graph connecting the two points. The gradual decline model D created in this manner is a graph in which the horizontal axis represents the period of time that has passed since the building was newly constructed, and the vertical axis represents the natural frequency of the building. As shown in FIG. 2, the straight line of this gradually decreasing model D shows a characteristic in which the natural frequency gradually decreases over time.

Moreover, the natural frequency of the building 6 (see FIG. 3) in this gradually decreasing model D is proportional to the rigidity of the building. Therefore, this gradual decrease model D shows that the stiffness decreases with the passage of time. Using the gradual decrease model D as described above, it is possible to predict changes over time in the rigidity of the building.

When the calculation unit 1 calculates the natural frequency at a specific point in time, vibration sensors 7 and 8 are installed at two locations, at the bottom and the top of the building 6 to be measured. Detect vibration. When this constant vibration data is input to the calculation unit 1, the calculation unit 1 performs vibration analysis to calculate the current natural frequency, and stores the constant vibration data and the natural frequency in the storage unit 2.
Note that the natural frequency to be stored in the storage unit 2 may be calculated by a calculation device different from the calculation unit 1, and only the calculation result may be stored in the storage unit 2.

Furthermore, an equivalent model B of a building is stored in advance in the storage unit 2.
The stored equivalent model B, as shown in FIG. 4, consists of a mass point 9 indicating the mass m of the building, a spring member 10 indicating the stiffness k of the building, and a damper 11 indicating the damping Cb of the building.
In the first embodiment, the mass m is specified from building information such as the specifications of the building, and the damping Cb is specified from the vibration analysis. However, the attenuation Cb may be obtained by other calculations, or an attenuation value determined by other public standards may be used as is.
Further, the stiffness k of the building is calculated by the calculation unit 1 as a function of the natural frequency.

Next, a simulation using the system of the first embodiment will be explained.
Once the building 6 to be measured is specified, the calculation unit 1 calculates the natural frequency f0 at the time of new construction based on the building information at the time of new construction, and stores it in the storage unit 2. Note that if the natural frequency can be directly obtained from the building information at the time of new construction, the natural frequency f0 may be stored in the storage unit 2 via the input unit 4 without being calculated by the calculation unit 1. good.

Further, the current natural frequency f1 is obtained as follows.
As shown in FIG. 3, vibration sensors 7 and 8 are installed at the center of the bottom and top of the building 6 specified as the measurement target. These vibration sensors 7 and 8 detect constant vibration data of the building 6, and input the constant vibration data to the calculation unit 1 via the input unit 4. When the constant vibration data is input, the calculation unit 1 performs vibration analysis on this data to calculate the current natural frequency f1, stores this in the storage unit 2, and also stores the constant vibration data in the storage unit 2. .

After calculating the natural frequency f1, the calculation unit 1 sets the natural frequency f0 as the first natural frequency, sets the natural frequency f1 as the second natural frequency, and calculates a straight line passing through these natural frequencies f0 and f1. A gradual decline model D consisting of a graph is created and stored in the storage unit 2.
Note that when the natural frequency f0 cannot be determined from the building information at the time of new construction, the first and second natural frequencies may be determined by measuring at least twice with a time difference maintained.

The gradual decline model D created in this manner shows that the stiffness of the building decreases over time. Therefore, as already explained, it is possible to predict the change in stiffness of the building over time using the gradually decreasing model D.

The calculation unit 1 calculates the damping Cb of the building 6 based on the constant vibration data stored in the storage unit 2, and stores this in the storage unit 2. Furthermore, the mass m specified from the building characteristics is also stored in the storage unit 2 via the input unit 4.
Once the attenuation Cb and mass m are stored in the storage unit 2 as described above, the calculation unit 1 applies these attenuation Cb and mass m to the equivalent model B and stores the equivalent model B in the storage unit 2.

In the first embodiment, seismic limit values and assumed seismic waveforms are stored in the storage unit 2 in advance.
The seismic limit value is the limit displacement that can maintain the integrity of the building when earthquake force is applied to the building, and in the first embodiment, the interstory displacement angle θ of the building 6 = 1/200 [rad ] is defined as the limit displacement amount δL.

Specifically, when the above interstory displacement angle θ = 1/200 [rad] is input to the calculation unit 1, the calculation unit 1 calculates the horizontal limit displacement from this interstory displacement angle θ and the height h of the building. The amount δL is calculated and stored in the storage unit 2. In the first embodiment, the limit displacement amount δL is the seismic limit value of the present invention, but the method and value of the limit displacement amount δL may be determined depending on the actual condition of the building.

Furthermore, in the first embodiment, the storage unit 2 stores a plurality of assumed seismic waveforms W1 to Wn, which are vibration waveforms within a set time. The assumed earthquake waveforms W1 to Wn are waveforms based on actual earthquakes that occurred in areas close to the building. However, if there is no appropriate seismic waveform data for a nearby area, the area may be expanded further and data from the nearby area may be used as much as possible. In any case, the assumed earthquake waveforms W1 to Wn are created based on data of earthquakes that actually occurred.

Once the limit displacement amount δL and the plurality of assumed seismic waveforms W1 to Wn are determined as described above, the calculation unit 1 selects one of the assumed seismic waveforms W1 to Wn. Then, the calculation unit 1 specifies the stiffness k of the spring member 10 based on the current natural frequency f1 stored in the storage unit 2, and applies vibration corresponding to the assumed seismic waveform W1 to the equivalent model B. . Then, the calculation unit 1 calculates the displacement amount δ in units of time within the set time.

Note that when vibration of a specific assumed seismic waveform is applied to the equivalent model B in which the stiffness k based on the natural frequency f1 is specified, the above-mentioned equivalent model B has the above-mentioned mass m, the above-mentioned damping Cb, the above-mentioned stiffness k, etc. Shaking occurs according to the characteristics of. In other words, the way equivalent model B shakes is not determined only by the assumed earthquake waveform.

For example, if the assumed seismic waveform and the equivalent model B resonate due to the characteristics of the equivalent model B, the amount of displacement δ in units of time may be calculated to be large even if the amplitude of the assumed seismic waveform is small. On the other hand, if the assumed seismic waveform and equivalent model B do not resonate, even if the amplitude of the assumed seismic waveform is large, depending on the characteristics of the above-mentioned equivalent model B, the shaking caused by the assumed seismic waveform may be absorbed or canceled out. Therefore, the displacement amount δ in units of time may be calculated to be small.
In this way, unlike the case where the displacement amount δ is calculated using only the amplitude of the assumed seismic waveform, by using the equivalent model B, it is possible to calculate the displacement amount δ in units of time taking into account the current state of the building.

When the displacement amount δ in units of time is detected as described above, the calculation unit 1 determines whether or not there is any displacement amount δ in units of time that exceeds the above-mentioned limit displacement amount δL.
If any of the displacement amounts δ in units of time exceeds the limit displacement amount δL, the calculation unit 1 stores the natural frequency f1 at this time in the storage unit 2 as a comparison natural frequency f1x.

Further, if there is no displacement amount δ exceeding the limit displacement amount δL, the calculation unit 1 selects an estimated natural frequency f2 that is smaller than the natural frequency f1. This estimated natural frequency f2 may be calculated by the calculation unit 1 itself, or may be input from the outside via the input unit 4. After selecting the estimated natural frequency f2, the calculation unit 1 calculates the displacement amount δ in units of time as in the case of the natural frequency f1, and determines whether any of the displacement amounts δ exceeds the limit displacement amount δL. Determine whether or not.

Note that how much the next estimated natural frequency f2 should be made smaller than the above natural frequency f1 may be artificially determined in consideration of the state of the building. For example, if the current natural frequency of the building is sufficiently large and it is likely to take a long time to reach the seismic limit value, the estimated natural frequencies f2 to fn may be reduced overall to The calculation time required to determine the vibration frequency can be reduced. On the other hand, if the seismic limit value is likely to be exceeded soon, do not make the difference from the current natural frequency f1 too large and increase the estimated natural frequency as a whole, so that the seismic limit value will be exceeded. Comparison natural frequencies f1x to fnx can be specified with high accuracy.

In this way, when the displacement amount δ in time units corresponding to the natural frequency f1 is detected for the assumed earthquake waveform W1, the calculation unit 1 determines whether any of the displacement amounts δ in time units exceeds the limit displacement amount δL. judge whether
If there is no displacement amount δ in units of time that exceeds the limit displacement amount δL, the calculation unit 1 moves on to simulation using the equivalent model B to which the next estimated natural frequency f2 is applied.

Note that once the comparative natural frequency f1x is determined based on the displacement amount δ in units of time corresponding to the natural frequency f1, simulations regarding the smaller natural frequencies f2 to fn are not performed. However, after setting multiple estimated natural frequencies in advance and completing the calculation of the displacement amount δ in units of time based on all of these estimated natural frequencies, the maximum natural frequency among them that exceeds the limit displacement amount δL The natural frequency of may be set as the comparison natural frequency f1x.

Then, the calculation unit 1 repeats the simulation for determining the comparative natural frequencies f2x to fnx for each of the assumed seismic waveforms W2 to Wn, in the same way as it did for the assumed seismic waveform W1. At this time, the mass m and damping Cb in the equivalent model B are kept constant, and the simulation is repeated for each of the assumed seismic waveforms W1 to Wn using only the stiffness k corresponding to the natural frequency as a variable.
As a result, the calculation unit 1 specifies n comparison natural frequencies f1x to f1n corresponding to each of the assumed seismic waveforms W1 to Wn. A reference natural frequency fx of the present invention is specified from among these comparative natural frequencies.

When the above-mentioned simulation is completed for all the assumed seismic waveforms W1 to Wn, the calculation unit 1 specifies the reference natural frequency fx according to a rule set in the calculation unit 1 in advance. In the first embodiment, the largest comparative natural frequency among the comparative natural frequencies f1x to fnx is set as the reference natural frequency fx. The reason for choosing the maximum value in this way is to calculate the service life with safety in mind. Therefore, if safety can be set roughly, a rule may be set that selects a value other than the maximum value.

In the first embodiment, a plurality of assumed seismic waveforms are used in the simulation, but only one assumed seismic waveform may be used. In that case, one comparative natural frequency f1x corresponding to the assumed seismic waveform W1 is directly set as the reference natural frequency fx.

Once the reference natural frequency fx is specified as described above, the calculation unit 1 substitutes the reference natural frequency fx into the gradually decreasing model D shown in FIG. Calculate.
Further, the calculation unit 1 causes the storage unit 2 to store the calculated service life and outputs it from the output unit 5.

As described above, in the first embodiment, based on the current natural frequency and the gradually decreasing natural frequency, the seismic limit value is specifically set, and the amount of displacement in the hour unit exceeds the seismic limit value. Since we are determining whether or not it exceeds the specified lifespan, it is not something that is fixed uniformly like the legal service life, but rather reflects the individuality of the building. Therefore, it is possible to calculate the service life that matches the actual condition of the building, and it can be used as an index for evaluating the value of the building.

Next, a useful life evaluation system according to the second embodiment will be explained.
The system of the second embodiment includes a calculation device 3 including a calculation section 1 and a storage section 2, an input section 4, and an output section 5, similarly to the first embodiment shown in FIG.
The calculation unit 1 specifies the standard natural frequency fx, and calculates the service life of the building by applying the specified standard natural frequency fx to the gradually decreasing model D (see FIG. 2), which is the same as in the first embodiment. is the same as However, the method of specifying the reference natural frequency fx is different from that of the first embodiment.

In this second embodiment as well, the storage unit 2 stores the gradual decrease model D of the natural frequency and the equivalent model B of the building, but these gradual decrease model D and the equivalent model B are different from the current one as in the first embodiment. It is created by the calculation unit 1 based on the natural frequency f1 of the building.

Further, the calculation unit 1 calculates the displacement amount (interlayer displacement angle θ) and the resistance force shown in FIG. 5 based on the resistance force generated in the spring member 10 when the mass point 9 of the equivalent model B is displaced in the horizontal direction. Calculate the correlation characteristics of

In FIG. 5, a solid line graph 12 is a correlation characteristic calculated based on the natural frequency f1 of the building at the current time, and the area in this graph 12 where the amount of displacement and the resistance force are directly proportional is the elastic area.
The slope of graph 12 in this correlation characteristic changes depending on the stiffness k, but since the stiffness k in this equivalent model B corresponds to the natural frequency as described above, the slope of graph 12 also changes according to the natural frequency. It will correspond to the number.

After creating the graph 12, the calculation unit 1 specifies the elastic limit point P1 in the graph 12. This elastic limit point P1 is the limit point at which the current building returns to its original state after being deformed.
After specifying the elastic limit point P1, the resistance force S1 corresponding to the elastic limit point P1 is specified.

Furthermore, the calculation unit 1 determines a resistance force S2 that is smaller than the resistance force S1. This resistance force S2 is calculated according to a rule set in advance in the calculation unit 1, such as 50% or 30% of the resistance force S1.

After determining the resistance force S2 based on the elastic limit point P1 as described above, the calculation unit 1 sets the point where the resistance force S2 occurs at the same interstory displacement angle θ1 as the elastic limit point P1 as the seismic limit point PL. .
However, the graph 12 of the correlation characteristics created by the calculation unit 1 may be output from the output unit 5, and the operator may artificially determine the seismic limit point PL while looking at the output correlation characteristics. When artificially determined in this way, the value of the resistance force S2 corresponding to the seismic limit point PL is stored in the storage unit 2 via the input unit 4.

Once the seismic limit point PL corresponding to the above-mentioned resistance force S2 is specified, the calculation unit 1 creates a graph 13 of the displacement-resistance force correlation characteristic passing through the zero point in FIG. 5 and the above-mentioned seismic limit point PL. After creating this graph 13, the calculation unit 1 calculates the natural frequency corresponding to this graph 13, and specifies it as the reference natural frequency fx.
After specifying the reference fixed frequency fx, the calculation unit 1 applies the reference natural frequency fx to the gradually decreasing model D to calculate the service life.
Further, the calculation unit 1 causes the storage unit 2 to store the calculated service life, and outputs it from the output unit 5.

The service life in this second embodiment is also calculated using the natural frequency of the building at a specific point in time, and is not uniformly determined by the classification of the building, unlike the legal service life. Therefore, it can be used as an index for value evaluation that matches the actual condition of the building.
Furthermore, in the second embodiment, as in the first embodiment, the equivalent model B is used, so that it is possible to evaluate the service life taking into account the current state of the building.

Note that any of the calculation processes of the calculation unit 1 in the first and second embodiments may be executed by a device other than the calculation unit 1 or performed by a person, and the calculation results may be inputted from the input unit 4. You can do it like this. In any case, if the gradual decline model D is created and the reference natural frequency fx is specified, the service life can be specified.

Furthermore, in both the first and second embodiments, the natural frequency of a building at a specific point in time can be calculated based on actually measured vibration data, but if a new natural frequency is calculated, The gradual decrease model D can be re-created using this method. Even if the gradually decreasing model D is created based on the natural frequency at a specific point in time, if the condition of the building changes due to an earthquake that occurs afterwards, there will be a discrepancy between the gradually decreasing model D and the actual state of the building. There is a possibility that this may occur. Once the gradual decline model D is created, if the above gradual decline model D is created again based on new measured data, the accuracy of the gradual decline model D can be increased, and the above service life specified by this system can be improved. It becomes more realistic.

The method and system for evaluating the useful life of a building according to the present invention are suitable for calculating the substantial useful life of a building.

1 Arithmetic unit 2 Storage unit 3 Arithmetic unit 4 Input unit 5 Output unit 6 Buildings 12, 13 (Displacement-resistance force correlation characteristic) graph D Gradual decrease model (of natural frequency) B Equivalent model (of building) f1x~ fnx Comparison natural frequency fx Standard natural frequency W1~Wn Assumed seismic waveform f2~fn Estimated natural frequency δL, PL Seismic limit point δ Displacement θ (Displacement) Interstory displacement angle

Claims (9)

A process of creating a gradually decreasing model D of natural frequency that decreases over time in the building to be measured;
A process of creating an equivalent model B of the building;
A process for setting seismic limit values for the above-mentioned buildings;
A process of identifying a reference natural frequency fx that exceeds the seismic limit value using the equivalent model B;
A method for evaluating the service life of a building, which performs a process of applying the identified standard natural frequency fx to the gradual decline model D to specify the service life of the building. The process of specifying the reference natural frequency fx is as follows :
A process for identifying expected seismic waveforms;
A process of vibrating the equivalent model B based on the assumed seismic waveform;
A process of specifying the amount of displacement of the equivalent model B,
2. The method for evaluating the service life of a building according to claim 1, further comprising the step of specifying a reference natural frequency fx based on the natural frequency at which the specified displacement exceeds the seismic limit value. The process of specifying the reference natural frequency fx is as follows :
A process for identifying expected seismic waveforms;
a process of determining a plurality of estimated natural frequencies from the natural frequencies of a building at a particular point in time;
A process of vibrating the equivalent model B at each of the plurality of estimated natural frequencies based on the assumed seismic waveform;
A process of specifying the amount of displacement of equivalent model B based on each of the above estimated natural frequencies;
2. The method for evaluating the service life of a building according to claim 1, further comprising a process of setting an estimated natural frequency when the specified displacement exceeds the seismic limit value as a reference natural frequency. The process of specifying the reference natural frequency fx is as follows :
A process of identifying multiple assumed seismic waveforms;
a process of identifying a plurality of estimated natural frequencies from the natural frequencies of the building at a particular point in time;
A process of associating the plurality of estimated natural frequencies with each of the plurality of assumed seismic waveforms and vibrating the equivalent model B for each of the estimated natural frequencies;
A process of identifying the amount of displacement of equivalent model B based on each estimated natural frequency for each of the above assumed earthquake waveforms;
a process of identifying an estimated natural frequency at which the identified displacement amount exceeds the seismic limit value as a comparison natural frequency for each of the assumed seismic waveforms;
A process of comparing the comparative natural frequencies,
The method for evaluating the service life of a building according to claim 1, further comprising a process of specifying a reference natural frequency fx based on the comparison result. The process of specifying the reference natural frequency fx is as follows:
A process of identifying the elastic limit point of the building in the displacement-resistance correlation characteristic using the equivalent model B;
In the displacement-resistance correlation characteristic, a process of setting the seismic limit point of the building in a resistance range below the elastic limit point;
2. The method for evaluating the service life of a building according to claim 1, further comprising a process of setting the natural frequency at which the seismic resistance limit occurs as the reference natural frequency fx. an arithmetic unit;
a storage unit connected to the arithmetic unit;
an input section for inputting data into the arithmetic section or storage section;
It consists of an output section that outputs the calculation results calculated by the above calculation section,
In the above storage section,
A gradual decrease model D of natural frequency that decreases over time, which is created based on the natural frequency of the building to be evaluated at a specific point in time, is stored.
The above calculation section is
A function to set seismic limit values,
When an equivalent model B of the building whose natural frequency is a parameter is input from the storage section or the input section, the function is to specify the reference natural frequency fx in which the equivalent model B exceeds the seismic limit value. ,
A function of applying the identified reference natural frequency fx to the gradual decrease model D to identify the number of years that have passed corresponding to the reference natural frequency fx;
A system for evaluating the useful life of a building, which has a function of calculating the useful life based on the specified elapsed number of years and outputting it to the output section. In the above storage section,
one or more assumed earthquake waveforms are stored;
The above calculation section is
A function of applying a plurality of estimated natural frequencies to the equivalent model B and vibrating the equivalent model B with the assumed seismic waveform;
A function that calculates the amount of displacement of the equivalent model B due to the vibration for each of the assumed earthquake waveforms and each estimated natural frequency;
A function that identifies, for each of the above-mentioned assumed earthquake waveforms, an estimated natural frequency in which the maximum value of the displacement amount calculated for each of the above-mentioned assumed earthquake waveforms exceeds a preset seismic limit value, as a comparison natural frequency;
7. The building service life evaluation system according to claim 6, further comprising a function of specifying a reference natural frequency fx from the comparison natural frequency based on a preset rule. The above calculation section is
A function of creating a displacement-resistance force correlation characteristic based on the natural frequency at the specific point in time using the equivalent model B;
A function to identify the elastic limit point in this displacement-resistance correlation characteristic,
A function to set the seismic limit value in the range of resistance below the elastic limit point,
7. The building service life evaluation system according to claim 6, wherein the displacement-resistance correlation characteristic has a function of specifying a natural frequency that overlaps the seismic limit point as the reference natural frequency fx. The above calculation section is
A function of creating the gradual decrease model D based on the natural frequency of the building at a specific point in time, which is input from the storage unit or the input unit;
The building according to claim 7 or 8, further comprising a function of creating the equivalent model B based on the height, mass, and natural frequency of the building at the specific time inputted from the storage section or the input section. A system for evaluating the useful life of objects.

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