JP3952851B2 - Seismic performance evaluation method and apparatus for buildings - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for objectively and quickly evaluating the seismic performance of a building during an earthquake, and more specifically, the inertial force-horizontal displacement relationship at a position representing the behavior of a building during an earthquake, Calculate the damage experienced by the building during the earthquake by measuring with the acceleration sensor placed in the building, and calculate the acceleration / displacement response spectrum from the input seismic motion measured by the acceleration sensor of the foundation, and compare the two The present invention relates to a method and an apparatus for evaluating seismic performance of a building that can evaluate and display the degree of damage and residual seismic performance of the building.
[0002]
[Prior art]
It is expected that many buildings will be damaged when a huge earthquake occurs. For example, during the 1995 Hyogoken-Nanbu Earthquake, about 310,000 people were damaged, and the number of fully and partially destroyed buildings exceeded 80,000 in Kobe alone.
[0003]
After the earthquake, it is necessary to determine whether it is possible to enter the building, safety of residence, and so on, and emergency risk determination is performed. This emergency risk determination is made exclusively by visual inspection by engineers and designers.
[0004]
[Problems to be solved by the invention]
However, in the conventional method that relies on the visual observation of engineers / designers, it takes many days of investigation (for example, it took about 40 days in the case of the earthquake disaster), and quick judgment cannot be made. In addition, in visual inspections, determination results often vary depending on the experience and skill level of engineers, designers, etc., and there is a disadvantage that objectivity is poor. Furthermore, the number of gray judgments that require “caution” is significantly higher than the clear judgments that are “dangerous” or “safe”, and the necessity of detailed surveys has led to an increase in the number of survey days.
[0005]
If a technology is established that can quickly and accurately determine how much earthquakes can be withstood after the earthquake, the affected buildings can be selected appropriately and quickly. The secondary disaster for aftershocks can be reduced, and the number of unnecessary evacuees can be reduced.
[0006]
An object of the present invention is to provide a technique capable of quickly and objectively determining the remaining seismic performance of a building after the occurrence of an earthquake (how much earthquake remains in the building). Another object of the present invention is that it is possible to appropriately and quickly select damaged buildings, so that secondary disasters against aftershocks can be reduced, and the number of unnecessary evacuees can be reduced. The object is to provide a method and apparatus for evaluating the seismic performance of buildings.
[0007]
[Means for Solving the Problems]
The present invention calculates the absolute displacement at the measurement point by integrating the acceleration measurement values measured by the acceleration sensors installed on at least the foundation and the upper floor of the building into the second floor, and assumes the vibration mode shape of the building to each floor of the building. The relative displacement and absolute acceleration of the building are calculated, and the representative displacement that represents the response deformation of the building and the representative acceleration that represents the response acceleration of the building are calculated from these values to obtain the building performance curve. Acceleration response spectrum and displacement response spectrum are calculated as input seismic motion input to the building, and the required curve of the building is obtained, and the residual seismic performance of the building is judged by comparing the performance curve and the required curve. This is a method for evaluating the seismic performance of buildings.
[0008]
Further, the present invention calculates the absolute displacement at the measurement point by integrating the acceleration measurement values measured by the acceleration sensors installed on at least the foundation and the upper floor of the building at the second floor in the event of an earthquake. Assuming that the relative displacement and absolute acceleration of each floor of the building are calculated, the representative displacement Sd representing the response deformation amount of the building and the representative acceleration Sa representing the response acceleration of the building are calculated from these values, and the Sa-Sd curve is calculated. Create a performance curve as a pseudo-envelope, estimate the performance curve up to the limit deformation of the building, and on the other hand, acceleration response spectrum Ra at 5% attenuation as input seismic motion input acceleration data at the base to the building And the displacement response spectrum Rd is calculated and the Ra-Rd curve is created to obtain the demand curve of the main shock, and the residual resistance is determined by the expansion rate when the demand curve is expanded so as to pass through the limit point of the building. It is a seismic performance evaluation method of the building, characterized in that to evaluate the performance.
[0009]
Further, according to the present invention, an acceleration sensor is installed on at least the base and upper floor of a building, a data recording / processing device having an A / D converter, a data recording unit, and a data processing display unit is installed, and an analog signal cable is used. It is a building seismic performance evaluation device that connects each acceleration sensor to a data recording / processing device, executes the above-described method by a seismic performance evaluation program installed in the data recording / processing device, and displays a determination result.
[0010]
The present invention also provides a unitized data recording apparatus having an acceleration sensor, an A / D converter, a CPU, and storage means, and storing acceleration data as digital data in the storage means by trigger processing when an earthquake occurs. Installed at least on the base and upper floors, provided with a data processing display device that receives the recorded digital data in a wired or wireless manner, and executed the above method by the seismic performance evaluation program installed in the data processing display device It is a seismic performance evaluation device for a building that displays a determination result. Data transmission / reception between the data recording device and the data processing display device by a wired method or a wireless method may be arbitrary, such as a LAN, a carrier using a telephone line or a power line, a method using a wireless telephone, or the like. However, in these configurations, since the time axis needs to be common when collecting waveform data, some synchronization function such as connecting a cable for synchronization signals or recording the exact time with each data recording device It is necessary to have.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
As a basic equipment arrangement configuration, as shown in FIG. 1, acceleration sensors 10a and 10b are respectively installed on the foundation (for example, the first floor) and the upper floor (preferably the top floor) of the building. In practice, it is preferable to provide an acceleration sensor at the center of the floor of the building, with one guide for every 3rd to 4th floors. Then, the data recording / processing device 12 is installed at an arbitrary position (for example, the base). This data recording / processing device 12 obtains the building response and the input ground motion at the time of the earthquake, obtains the residual seismic performance (how much the earthquake can survive), and displays whether it is dangerous or safe. As a result, it is possible to determine the safety of the building after the earthquake almost in real time.
[0012]
The data recording / processing device 12 is loaded with a seismic performance evaluation program having the following functions.
(1) The absolute response deformation amount of the entire building is calculated by second-order integration of the measured value of the acceleration sensor.
(2) By appropriately assuming the mode shape of the building, the relative displacement and absolute acceleration of each floor of the building are calculated, and from these values, the representative displacement representing the response deformation amount of the building and the representative representing the response acceleration of the building Calculate the acceleration to calculate the building performance curve.
(3) Calculate the acceleration response spectrum and the displacement response spectrum as the input seismic motion obtained by inputting the acceleration measurement value of the foundation to the building to obtain the required curve of the building.
(4) From the comparison of the obtained performance curve and the required curve, evaluate the residual seismic performance of the building and display the result.
[0013]
As described above, the point that the performance curve / required curve is appropriately created without detailed design information with respect to the response of the actual building, and the point that the remaining seismic performance is determined from these curves are not in the prior art. It is a big feature.
[0014]
FIG. 2 shows an outline of the determination. The required curve at 5% attenuation of the mainshock will be expanded so that the building performance curve obtained up to the limit deformation intersects at the limit deformation point. This expansion rate γ means seismic performance. When this γ is 1 or more, it is judged as “safe” for aftershocks (usually aftershocks are not considered to exceed the mainshock). It is judged as “dangerous”. In other words, the critical deformation point is “dangerous” if it is inside the required curve with 5% attenuation of the mainshock, and “safe” if it is outside. If the building stays within the elastic range, it is judged as “elastic” by checking its rigidity separately.
[0015]
【Example】
For example, assume a three-story building as shown in FIG. The three-story building can be modeled as three mass points (mass: M ₁ , M ₂ , M ₃ ) corresponding to each floor, as shown in B. When a horizontal force (P ₁ , P ₂ , P ₃ ) is applied to this three-mass system model in the same way as during an earthquake, as shown in C, according to the external force distribution assuming the force generated by inertia during the earthquake, As shown in D, deformation (X ₁ , X ₂ , X ₃ ) occurs, and each floor bears a horizontal force (layer shear force). The relationship between the layer shear force of each floor and the interlayer deformation is as shown in FIG. 4, and it can be seen that each floor is damaged according to the proof stress possessed and exhibits non-linearity. The relationship between the layer shear force of each floor and the interlayer deformation can be replaced with a performance curve representing them according to the external force distribution shown in FIG.
[0016]
On the other hand, an acceleration response spectrum Ra of seismic motion taken along the vertical axis and a displacement response spectrum Rd taken along the horizontal axis is called a demand curve. In order to calculate Ra and Rd, it is necessary to assume a damping constant, but the damping constant at the time of elasticity of a general building can be 5%. In addition, when damage arises in a building, damping force acts additionally according to the nonlinearity by the damage. The response of the building at the time of an earthquake is the point where the performance curve shown in FIG. 5 intersects with the required curve considering this additional damping force. Thus, once the performance and demand curves are obtained, the building response is predictable.
[0017]
In the method of the present invention, this response spectrum method is applied to an actual earthquake response of an actual building. Under actual earthquake motion, the external force acting on the building is not a simple one as shown in C of FIG. 3 and includes higher-order mode components up to the third-order mode. This actual response is measured by a relatively small number of acceleration sensors, and the floors that are not measured are calculated by assuming a mode shape of the building, and a performance curve is obtained from the response of the actual building. Seismic motion input to the building can be measured by an acceleration sensor installed on the base of the building (for example, the first floor). A demand curve is obtained from this ground motion.
[0018]
In the response spectrum method, a response value is obtained from a demand curve. However, in this method, the maximum required curve that the building can withstand is obtained by expanding the required curve so that the required curve passes through the limit point of the performance curve (see FIG. 7). The seismic performance of the building is evaluated from the ground motion level of this maximum demand curve.
[0019]
FIG. 6 is a flowchart of processing / determination showing one embodiment of the method for evaluating seismic performance of buildings according to the present invention. The numbers in parentheses below correspond to the numbers in parentheses in FIG.
(1) The acceleration _m α _j is measured by an acceleration sensor arranged on the foundation and the top floor of the building.
(2) The measured acceleration _m α _j is second-order integrated to calculate the absolute displacement at the measurement point. By subtracting the absolute displacement at the foundation from each absolute displacement, the relative displacement _m X _j with respect to the foundation at the measurement point is calculated.
(3) Assuming a vibration mode shape of the building (here, a mode shape in which measurement points are connected by straight lines is adopted). Of course, the mode shape itself may be measured.
(4) The relative displacement _c X _j of each floor is calculated from the mode shape of (3) and the relative displacement _m X _j of (2).
(5) The absolute acceleration _c α _j of each floor is calculated from the mode shape of (3) and the measured acceleration _m α _j of (1).
(6) to enter the floor of the mass ratio m _i in the height direction. This mass ratio is, for example, a floor area ratio. If each floor has the same mass, m _i = 1.0.
(7) Using _c X _{j in} (4) and m _{i in} (6), a representative displacement Sd representing the response deformation amount of the building is calculated by the following equation.
Sd = (Σm _i · _c X _i ) / (Σm _i · _c X _i ² )
(8) Using _c α _{j in} (5) and m _{i in} (6), a representative acceleration Sa representing the response acceleration of the building is calculated by the following equation.
Sa = (Σm _i · _c α _i ) / (Σm _i )
(9) Create a Sa-Sd curve (performance curve) with the horizontal axis of Sd in (7) and the vertical axis of Sa in (8).
(10) During an actual earthquake, the performance curve in (9) draws a loop. Therefore, a point that is the maximum value of the performance curve until that time is extracted (pseudo-envelope). As a result, the performance curve indicated by a in FIG. 7 is obtained. In addition, the maximum response point a-1 of the main shock is automatically obtained at the end of the earthquake.
(11) The limit deformation Ru of the building is input (a-2 in FIG. 7). This limit deformation takes the method of assuming the limit deformation amount for each group by dividing the building into three groups according to the building year, since 1971 and 1981 when the Building Standards Law was greatly revised. . At that time, the building subjected to the earthquake-resistant diagnosis may determine the limit deformation according to the diagnosis result. Alternatively, using the ratio of the horizontal deformation amount to the height of each floor (interlayer deformation angle), a limit deformation angle of several patterns is assumed depending on the building age and the structure type (for example, the interlaminar deformation angle 1/50 is used as the limit deformation angle, etc.) ), There is also a method of assuming the critical deformation. In addition, there is also a method in which the limit point is a point where the yield strength is lowered despite the progress of deformation in the performance curve (for example, the point where the yield strength is reduced to 50%). In the future, it is possible to further embed a sensor in a column or beam and measure the information about the amount of limit deformation.
(12) The performance curve up to the limit deformation point is estimated by extending the performance curve obtained in the above (10) to the limit deformation (a-3 in FIG. 7).
(13) Considering the acceleration _m α ₀ at the foundation measured in (1) above as the input ground motion input to the building, the acceleration response spectrum Ra and the displacement response spectrum Rd are calculated from _m α ₀ . The attenuation constant at this time is 5%. If the angular frequency is calculated for a certain period and the damping constant is assumed, the response time history of the building can be calculated by integrating the motion equation of the elastic building of one mass system for the duration of the earthquake motion. The maximum absolute acceleration response and maximum response deformation can be selected during the duration of the earthquake motion. The acceleration response spectrum Ra is obtained by taking the maximum absolute acceleration response on the vertical axis with the period as the horizontal axis, and the displacement response spectrum Rd is obtained by taking the maximum response deformation amount on the vertical axis.
(14) Create a Ra-Rd curve with the vertical axis of Ra and the horizontal axis of Rd in (13) above. This Ra-Rd curve is a required curve at 5% attenuation. In a real building, when the building becomes non-linear, energy is absorbed by the non-linearity, thereby causing an attenuation of 5% or more. Attenuation lowers the Ra-Rd curve.
(15) To what extent the building can withstand future earthquake motion is judged from the Ra-Rd curve at 5% attenuation and the performance curve of (12). Specifically, the Ra-Rd curve is expanded so that the obtained Ra-Rd curve passes through a building limit point (a-2 in FIG. 7). The Ra-Rd curve thus obtained is the maximum required curve that the building can withstand (c in FIG. 7). If this enlargement rate is γ, the damaged building can withstand γ times the main shock. At this time, if γ <1.0, it will not be able to withstand the ground motion at the level of the main shock, and is judged as “dangerous”. When γ ≧ 1.0, it is determined as “safe”. Although the maximum required curve for determination (c in FIG. 7) uses 5% attenuation even though additional attenuation acts due to non-linearity, this accurately determines additional attenuation due to non-linearity. This is because it is difficult to do and evaluates on the safe side. Even after the earthquake, if the performance curve of the building is in the elastic range, even if the straight line is extended to the limit displacement, it does not become a performance curve. In this case, the determination of “elasticity” is made.
(16) As a device, the determination result obtained in (15) above is displayed on the determination device in an easy-to-understand manner. It is also possible to numerically display how much residual seismic performance is present.
[0020]
The second order integration for obtaining the displacement from the acceleration recording is roughly divided into a method in the time domain and a method in the frequency domain. The former includes a method of directly integrating acceleration records and a method of passing through a digital filter that simulates an integration circuit. The latter usually uses FFT (Fast Fourier Transform). In the present invention, any method including these may be used.
[0021]
The basic configuration of the building seismic performance evaluation apparatus according to the present invention is as shown in FIG. Only the acceleration sensors 10a and 10b are installed on the required floor (in the example shown, the first floor and the top floor), and a data recording / processing device 12 having an A / D converter, a data recording section, a data processing display section, etc. Installed on the floor, the acceleration sensors 10a, 10b and the data recording / processing device 12 are connected by analog signal cables. The seismic performance evaluation program installed in the data recording / processing device 12 is executed and the determination result is displayed. Signals from the acceleration sensors 10a and 10b are received by the data recording / processing device 12, A / D conversion and data recording are performed on the data recording / processing device 12 side, and data processing based on them is performed. This method is the most common and is the same method used in existing seismic observation systems.
[0022]
FIG. 8 shows another configuration example of the building seismic performance evaluation apparatus according to the present invention. It is characterized in that the data recording device is unitized and can be easily installed at a predetermined position in the building. Here, it is assumed that the building has 10 floors. In this case, for example, the data recording devices 20 are installed on the top floor (10th floor), the base (1st floor), and the intermediate floor (for example, 5th floor). And the data processing display apparatus 40 which receives each data recorded with each data recording device 20 is installed in one place, for example, the 1st floor. Here, data is transmitted and received using a cable 42 such as RS232C or LAN. This configuration has an advantage that an intelligent building or the like can be directly connected to a LAN in the building. The data processing display device has a seismic performance evaluation program.
[0023]
In this embodiment, each data recording device 20 includes an acceleration sensor 22, an A / D converter 24, a data recording unit 26, an I / O interface 28, a power source (battery), and the like, and is housed in a robust case. Unit structure. The acceleration sensor 22 has a structure that can detect three components of X, Y, and Z and outputs a voltage corresponding to the magnitude of the acceleration. The output voltage is guided to the A / D converter 24 and converted into a 24-bit digital value by, for example, a sigma delta AD converter.
[0024]
The data recording unit 26 includes a time calibrator 30, a CPU 32, a storage means (memory) 34, and the like. When the acceleration value that is constantly detected exceeds a preset threshold value (when an earthquake occurs), a trigger is applied and acceleration data (waveform data) is automatically accumulated in the storage means 34, and a time calibrator (GPS time calibration) Time information by a device 30 or a radio clock) is also recorded. In this embodiment, the time calibrator 30 is incorporated in the collection of waveform data, and the time axis of the acceleration data to be recorded needs to be common. The time between each data recording device 20 and the recording start time This is because it is necessary to synchronize. If the synchronization function is established by connecting the data recording devices 20 or between the data recording devices 20 and the data processing display device 40 with a synchronization signal cable, the time calibrator is not provided. May be. When the shaking due to the earthquake subsides, the waveform recording is automatically terminated, and the data processing display device 40 on which the earthquake resistance performance evaluation program is installed automatically starts up and performs determination processing.
[0025]
In the determination process, displacement data is calculated by digital second order integration with respect to the acceleration data, the earthquake resistance evaluation program is executed with the acceleration data and the displacement data as inputs, and the earthquake resistance evaluation result is output and displayed.
[0026]
An arbitrary method may be used for sending and receiving data between each data recording device and the data processing display device. For example, a connection method using a power-carrying telephone may be used. This method is slightly less accurate but does not require new cables. Also, a method using a PHS, a mobile phone, or other wireless communication means may be used, and this method also has a high degree of freedom of installation because there is no need to lay cables.
[0027]
Therefore, in the system using these telephone lines and wireless communication means, it is not always necessary to install a data processing display device for each building, and one data processing display device is installed for a plurality of buildings in a certain area or the like. Therefore, it is possible to reduce the installation cost. Further, if it is not necessary to make a determination in real time, a method of processing data by connecting a data processing display device when a determination is required is possible.
[0028]
【The invention's effect】
As described above, the present invention is a method and an apparatus for evaluating seismic performance of a building that can measure the building response and input seismic motion during an earthquake with an acceleration sensor and quickly display the residual seismic performance. It is possible to quickly and objectively determine whether performance that can withstand up to Therefore, it is possible to appropriately manage the damaged building, reduce the secondary disaster due to the aftershock, and reduce the number of unnecessary evacuees. Since the measurement purpose is limited, the device can be manufactured at low cost, the degree of freedom of arrangement is widened, and the device can be easily installed. Therefore, the configuration is easy to spread and the effect on disaster prevention is extremely great.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a device arrangement configuration for carrying out the method of the present invention.
FIG. 2 is an explanatory diagram of building earthquake resistance determination according to the method of the present invention.
FIG. 3 is an explanatory diagram of a three-story building and its modeling.
FIG. 4 is a graph showing the relationship between (layer) deformation amount- (layer) shear force.
FIG. 5 is a relationship diagram of horizontal deformation amount Sd−shear force coefficient and response acceleration Sa for explaining the spectrum method.
FIG. 6 is a flowchart showing an example of an execution procedure of the method of the present invention.
FIG. 7 is an Sd / Rd-Sa / Ra relationship diagram for explaining an actual measurement procedure;
FIG. 8 is a block diagram showing an embodiment of the seismic performance evaluation apparatus according to the present invention.
[Explanation of symbols]
10a, 10b Acceleration sensor 12 Data recording / processing device

Claims (4)

The absolute displacement at the measurement point is calculated by integrating the acceleration measurement value measured by the acceleration sensor installed on at least the foundation and the upper floor of the building, and the relative displacement of each floor is calculated assuming the vibration mode shape of the building. The absolute acceleration is calculated, and from these values, the representative displacement that represents the response deformation of the building and the representative acceleration that represents the response acceleration of the building are calculated to obtain the performance curve of the building. On the other hand, the acceleration measurement value at the foundation Acceleration response spectrum and displacement response spectrum are calculated as input seismic motion input to the building to obtain the required curve of the building, and the residual seismic performance of the building is judged from the comparison of the performance curve and the required curve Seismic performance evaluation method. In the event of an earthquake, at least the basic part of the building and acceleration measurements measured by acceleration sensors installed on the upper floors are integrated into the second floor to calculate the absolute displacement at the measurement point, assuming the vibration mode shape of the building, and Relative displacement and absolute acceleration are calculated, a representative displacement Sd representing the response deformation amount of the building and a representative acceleration Sa representing the response acceleration of the building are calculated from these values, and a Sa-Sd curve is created to create a pseudo envelope As a result, an acceleration response spectrum Ra and a displacement response spectrum Rd at 5% attenuation are input as input seismic motions obtained by inputting acceleration measurement values at the foundation to the building. The Ra-Rd curve is calculated and the required curve of the main shock is obtained, and the residual seismic performance is evaluated by the expansion rate when the required curve is expanded so as to pass through the building limit point. Seismic performance evaluation method of the building, characterized in that. Install acceleration sensors on at least the foundation and upper floors of the building, install a data recording / processing device with an A / D converter, a data recording unit, and a data processing display unit. A seismic performance evaluation device for a building, which is connected to a recording / processing device and displays the determination result by executing the method according to claim 1 or 2 by a seismic performance evaluation program installed in the data recording / processing device. A unitized data recording apparatus having an acceleration sensor, an A / D converter, a CPU, and storage means, and storing acceleration data in the storage means as digital data by trigger processing in the event of an earthquake, at least the base and upper layer of the building A data processing display device is installed on the floor and receives the recorded digital data in a wired or wireless manner, and the method according to claim 1 or 2 is executed by a seismic performance evaluation program installed in the data processing display device. Seismic performance evaluation device for buildings that displays judgment results.

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