CN106248326A - The damage location identification method of high-rise frame structure based on natural frequency rate of change - Google Patents

Abstract

The invention discloses a damage position identification method of a high-rise frame structure based on the natural frequency change rate, comprising the following steps: extracting the frequency change rate k _f under different damage position indexes _PL ; establishing the frequency change rate k _f and the damage position index The relational expression of _PL ; the acceleration response value of a certain layer of the high-rise frame structure is measured by the acceleration sensor, and the frequency change rate k _f is extracted from the acceleration response value; it is substituted into the relational expression of the frequency change rate k _f and the damage location index _PL , back-calculate the damage index P _L . The existing damage identification method must use the current response signal of the structure to compare and analyze the response signal before the structure damage to identify the damage position. The present invention can identify the damage position of the structure only by analyzing the current response signal of the structure. The invention formulates the damage position of the structure and the frequency change rate, and the damage position of the structure can be accurately calculated by using the formula of the invention.

Description

Damage location identification method for high-rise frame structures based on natural frequency change rate

technical field

The invention relates to a structure position damage identification method, in particular to a damage position identification method of a high-rise frame structure.

Background technique

In today's building construction, high-rise frame structures are more and more widely used. However, with the effects of material aging, environmental corrosion, load effects, man-made damage, and natural mutation effects, these effects will inevitably lead to structural damage accumulation and Therefore, it is imminent to detect, identify, and evaluate the damage of high-rise frame structures by scientific means from the perspective of structural durability and safety.

The current identification methods based on the damage location of high-rise frame structures are all based on the comparison and analysis of the response signals before and after the damage, so as to locate the damage location of the structure.

However, in real life, the data before the structural damage will always be lost due to various reasons, which will cause huge interference to the identification of the structural frequency before the damage, which will inevitably affect the identification of structural damage information.

If the natural frequency change rate of the structure is used to identify the damage of the structure, the response signal before the structure damage is not needed, and only the current response signal of the structure is needed to analyze the damage position of the structure, which greatly reduces the workload of damage identification. There is no relevant report on how the natural frequency change rate can identify the damage location of the structure.

Contents of the invention

In order to solve the problems existing in the existing methods, the present invention provides a damage location identification method for high-rise frame structures based on the rate of change of natural frequency, which can use the current response signal of the structure to accurately identify the damage location of the structure.

In order to achieve the above object, the technical solution adopted in the present invention is as follows: the damage location recognition method of the high-rise frame structure based on the rate of change of natural frequency comprises the following steps:

A. Establish the relationship between frequency change rate k _f and damage location index _PL by simulation method

A1. Extract the frequency change rate k _f under different damage location indicators _PL

Using the numerical simulation method to obtain the acceleration response value of a specific layer of the structure when the stiffness reduction rate of different layers is the same, the frequency change rate k _f is extracted for the acceleration response value;

rate of change of frequency

In the formula: df is the variation of structure frequency in adjacent sampling time, dt is the sampling time interval;

damage location indicator

In the formula: c _n is the damaged layer of the structure, c is the total number of layers of the structure;

A2. Establish the relationship between the frequency change rate k _f and the damage location index _PL

Use the frequency change rate k _f obtained in step A1 to use the least squares fitting method to obtain the relationship between the frequency change rate k _f and the damage location index P _L

G(P _L ,k _f )=k'·P _L -k _f +C ₂ ＝0 (1)

In the formula: k _f is the rate of frequency change, _PL is the damage location index, k' and C ₂ are constants.

B. Use the measured acceleration response value after damage to calculate the damage position index P _L

B1. Measure the acceleration response value of a certain layer of the high-rise frame structure through the acceleration sensor, and extract the frequency change rate k _f from the acceleration response value;

B2. Substitute the frequency change rate k _f obtained in step B1 into formula (1), and calculate the damage index P _L back, and the calculation is published as follows:

P _L = (k _f - C ₂ )/k' (2)

Thus, the damage location index _PL of the structure is obtained.

Further, the method for extracting the frequency change rate k _f includes the following steps:

S1. Data preprocessing

The three-dimensional graph of time-frequency-amplitude is obtained by using the time-frequency analysis method on the acceleration response value. Then extract the frequency corresponding to the first peak point of the amplitude in the frequency-amplitude two-dimensional graph at each moment, that is, the first-order natural frequency of the structure at each moment;

S2. Extract frequency change rate k _f

Using the least squares fitting method, linear fitting is performed on the first-order natural frequency at each moment obtained in step S1 to obtain a function of frequency changing with time:

f(t)=k _f ·t+C ₁ (3)

In the formula: f(t) is the frequency, t is the time, and _C1 is a constant; through the formula (3), the value of the frequency change rate k _f can be obtained.

Further, the time-frequency analysis method described in step S1 is a short-time short-time Fourier transform method.

Further, the numerical simulation method includes a matlab numerical simulation method, ansys numerical simulation method or abaqus numerical simulation method.

Further, the specific layer mentioned in step A1 is the layer where the acceleration sensor is installed.

Further, the acceleration sensor is installed on any layer.

Compared with existing methods, the present invention has following advantages:

1. The existing damage identification method must use the current response signal of the structure to compare and analyze the response signal before the structure damage to identify the location of the damage. The present invention can identify the damage location of the structure only by analyzing the current response signal of the structure .

2. The existing damage identification method can only identify the damage position of the structure through the difference of the signal before and after the damage. This invention formulates the damage position of the structure and the frequency change rate, and the damage position of the structure can be accurately calculated by using the formula of the invention .

Description of drawings

Figure 1 is a flow chart of the present invention.

Fig. 2 is a flow chart of extracting the frequency change rate _kf .

Fig. 3 is a graph of frequency change rate k _f and damage location index _PL .

detailed description

The following describes how to use the first-order natural frequency change rate to identify the damage location of the high-rise frame structure in conjunction with the accompanying drawings.

For high-rise frame structures, when the stiffness reduction rates of different floors are the same, the damage of the lower floors will cause greater damage to the structure than the damage of the high floors. Therefore, for the same damage degree, the higher the damage layer, the smaller the damage factor of the structure. The greater the rate of frequency change. Through the analysis of a large number of test data, it is found that the frequency change rate has a linear relationship with the damage position of the structure.

Example:

The actual structure is a high-rise frame structure with twelve floors. Assuming that the stiffness reduction rate of a certain floor of the structure is 70% and the acceleration response value obtained by the acceleration sensor on the tenth floor, the damage location of the structure is calculated.

According to the process shown in Figure 1-2, use the matlab numerical simulation method to simulate a 12-story high-rise frame structure, and input El Centro seismic waves under ten working conditions such as the stiffness reduction of 70% in the third to twelfth floors of the structure to obtain For the acceleration response value of the tenth floor, the frequency change rate k _f is extracted according to step A for the acceleration response value of the tenth floor under each working condition, and the results are shown in Table 1. Draw the P _L -k _f diagram and the fitting results are shown in Figure 3.

Thus, the relational expression of P _L -k _f is obtained as follows:

P _L =(k _f +0.0128)/0.0095

For the acceleration response value obtained by the acceleration sensor on the tenth floor of the actual structure, the frequency change rate k _f =-0.01207 obtained in step A is substituted into the above formula to obtain

P _L =(-0.01207+0.0128)/0.0095=0.077

The damaged layer c _n =P _L ×c=0.077×12=0.924≈1, therefore, the damaged position of the structure is in the first layer.

Table 1P _L -k _f data sheet

P _L 3/12 4/12 5/12 6/12 7/12 8/12 9/12 10/12 11/12 1 _f -0.0106 -0.0097 -0.0088 -0.008 -0.0071 -0.0062 -0.0055 -0.0047 -0.0041 -0.0036

The present invention is not limited to this embodiment, and any equivalent ideas or changes within the technical scope disclosed in the present invention are listed in the protection scope of the present invention.

Claims (6)

1. the damage location identification method of high-rise frame structure based on natural frequency rate of change, it is characterised in that: include following Step:

A, set up frequency change rate k by emulation mode_fWith damage position index P_LRelational expression

A1, different damage position index P of extraction_LUnder frequency change rate k_f

Utilize numerical value emulation method obtain different layers Stiffness degradation rate identical time structure certain layer acceleration responsive value, to this Acceleration responsive value extracts frequency change rate k_f；

Frequency change rate

In formula: df is the variable quantity of consecutive sampling times inner structure frequency, dt is sampling time interval；

Damage position index

In formula: c_nFor the damage layer of structure, c is total number of plies of structure；

A2, set up frequency change rate k_fWith damage position index P_LRelational expression

The frequency change rate k that step A1 is obtained_fUse least-square fitting approach, obtain frequency change rate k_fWith damage position Index P_LRelational expression

G(P_L,k_f)=k'P_L-k_f+C₂=0 (1)

In formula: k_fFor frequency change rate, P_LFor damage position index, k', C₂For constant；

After B, utilization damage, the acceleration responsive value inverse of actual measurement goes out damage position index P_L

B1, measured the acceleration responsive value of a certain layer of high-rise frame structure by acceleration transducer, and to this acceleration responsive Value extracts frequency change rate k_f；

B2, the frequency change rate k that step B1 is obtained_fSubstitution formula (1), inverse goes out damage degree index P_L, calculate publicity as follows:

P_L=(k_f-C₂)/k' (2)

Thus obtain damage position index P of structure_L。

The damage location identification method of high-rise frame structure based on natural frequency rate of change the most according to claim 1, It is characterized in that: described extraction frequency change rate k_fMethod, comprise the following steps:

S1, data prediction

Time-Frequency Analysis Method is used to obtain the graphics of T/F-amplitude acceleration responsive value；Then each moment is extracted Frequency-amplitude X-Y scheme in the frequency corresponding to first peak point of amplitude, the intrinsic frequency of single order of the most each moment structure Rate；

S2, extraction frequency change rate k_f

Use least-square fitting approach, the first natural frequency in each moment obtained in step S1 is carried out linear fit and obtains To the time dependent function of frequency:

F (t)=k_f·t+C₁ (3)

In formula: f (t) is frequency, t is the time, C₁For constant；Frequency change rate k is i.e. obtained by formula (3)_fValue.

The damage location identification method of high-rise frame structure based on natural frequency rate of change the most according to claim 2, It is characterized in that: the Time-Frequency Analysis Method described in step S1 is Short Time Fourier Transform method.

The damage location identification method of high-rise frame structure based on natural frequency rate of change the most according to claim 1, It is characterized in that: described numerical value emulation method includes matlab numerical value emulation method, ansys numerical value emulation method or abaqus Numerical value emulation method.

The damage location identification method of high-rise frame structure based on natural frequency rate of change the most according to claim 1, It is characterized in that: the certain layer described in step A1 is to be provided with the place layer of acceleration transducer.

The damage location identification method of high-rise frame structure based on natural frequency rate of change the most according to claim 1, It is characterized in that: described acceleration transducer is arranged on any layer.