Structure splicing area damage early warning method based on improved acoustic emission energy index value

Abstract

The invention discloses a structure splicing area damage early warning method based on an improved acoustic emission energy index value, and relates to the field of splicing area damage early warning, and the method comprises the steps: S1, employing an acoustic emission signal in a test sampling stage, and determining a main frequency band signal in different interface connection modes according to the acoustic emission signal in the test sampling stage; s2, extracting effective acoustic emission signals of a main frequency band in different interface connection modes by using a digital filtering separation method; s3, calculating an improved acoustic emission Ib value of the effective acoustic emission signal of the main frequency band based on the effective acoustic emission signal; s4, improving the statistical process of the acoustic emission Ib value by controlling the loading process of the structure and the component; and S5, performing early warning on the damage of the splicing area according to the statistical process. According to the acoustic emission information extraction method based on the upper limit and the lower limit of the acoustic emission main frequency, different interface connection modes are considered, traditional empirical parameters are corrected, a new acoustic emission Ib value is obtained, and the accuracy of damage early warning of the assembly type structure is remarkably improved.

Description

Technical Field

[0001] The invention relates to the field of splicing area damage early warning, in particular to a structure splicing area damage early warning method based on improved acoustic emission energy index value. Background Art

[0002] Since the joint area of ​​the prefabricated structure is prone to damage when bearing loads, such as cracks, debonding and other problems. If these potential structural defects are not discovered and handled in time, they will pose a serious threat to the safety of the overall structure. Therefore, it is of great significance to conduct effective damage monitoring and comprehensive safety assessment of the joint area of ​​the prefabricated structure. However, the current acoustic emission monitoring technology for interface connection damage of prefabricated structures still has the following limitations:

[0003] Existing research and practice mostly focus on monitoring the damage of the entire wall, including damage location, degree judgment and identification. But in fact, reliable interface connection is the key factor to prevent structural damage caused by component adhesion and slippage. It is difficult to accurately provide effective stick-slip damage warning for prefabricated structures by only monitoring the damage of the entire wall.

[0004] In the existing invention, the acoustic emission Ib value is used to identify the damage of concrete components. However, when the damage of the splicing area of ​​the prefabricated structure is identified, the existence of the splicing area affects the characteristics of the acoustic emission Ib value, making it difficult to accurately use this method to identify the damage of the concrete splicing area.

[0005] Therefore, it is urgent to consider the impact of the splicing area of ​​the prefabricated structure on the acoustic emission Ib value in order to establish a more accurate prefabricated structure damage early warning method, so as to better identify the damage of the splicing area and ensure the stability and safety of the prefabricated structure.

[0006] Yan L et al. used the acoustic emission Ib value to warn the initial damage of fiber-reinforced concrete under cyclic tensile stress, thereby obtaining the damage evolution trend of the acoustic emission Ib value during the loading process, and used it as a damage warning indicator to identify the initial damage of the component. Liu Ruyue, Yang Yong et al. used the acoustic emission Ib value to warn the damage of continuous steel-concrete composite beams under cyclic loads, and obtained an acoustic emission Ib value of 2 as a warning indicator for damage to the composite beam.

[0007] The existing technology mainly monitors the damage of the entire structure through acoustic emission technology. In the identification of component damage, parameters (ring count, amplitude, energy, duration) are mainly used for judgment. It is impossible to accurately identify the damage of the splicing area of ​​the prefabricated structure, and it is also impossible to accurately evaluate the safety of the prefabricated structure. There are the following problems:

[0008] ① When the acoustic emission signal path passes through the splicing area, the different density / microstructure and interface gap will cause the acoustic emission signal to attenuate, thus affecting the damage detection accuracy.

[0009] ② Different interface connection methods will affect the amplitude, frequency and propagation characteristics of acoustic emission, thereby affecting the accuracy of damage warning. Summary of the invention

[0010] To solve the above problems, based on the defects and deficiencies of the prior art, the present invention aims to provide a structural splicing area damage warning method based on an improved acoustic emission energy index value, an acoustic emission information extraction method based on the upper and lower limits of the main frequency of acoustic emission, and a new acoustic emission Ib value is obtained by considering different interface connection methods, which significantly improves the accuracy of prefabricated structure damage warning. When applied to actual projects, it can not only timely discover potential damage in the splicing area of ​​the prefabricated structure, but also provide a scientific basis for the maintenance and repair of the structure, thereby significantly improving the overall safety and durability of the prefabricated building.

[0011] The structural splicing area damage early warning method based on the improved acoustic emission energy index value includes the following steps:

[0012] S1. Taking the acoustic emission signal of the trial sampling stage, determining the main frequency band signal under different interface connection modes according to the acoustic emission signal of the trial sampling stage;

[0013] S2, using digital filtering separation method to extract effective acoustic emission signals of the main frequency band under different interface connection modes;

[0014] S3, calculating the improved acoustic emission Ib value of the effective acoustic emission signal in the main frequency band based on the effective acoustic emission signal;

[0015] S4. Improve the statistical process of acoustic emission Ib value by controlling the loading process of structures and components;

[0016] S5. Provide early warning of damage to the splicing area based on the statistical process.

[0017] Preferably, the specific content of determining the main frequency band signal under different interface connection modes according to the acoustic emission signal in the trial sampling stage in S1 includes:

[0018] Use fast Fourier transform FFT to calculate the acoustic emission signal in the frequency domain;

[0019] The expression of Fast Fourier Transform FFT is:

[0020]

[0021] The maximum frequency of the acoustic emission signal is obtained by the calculation formula of the main frequency of the acoustic emission signal;

[0022] The calculation formula of the main frequency of acoustic emission signal is:

[0023] f p=max|f x |;

[0024] The quartile method was used to further determine the upper and lower limits of the quartile of the main frequency of acoustic emission;

[0025] The expression of the quartile method is:

[0026] f pu =f pQ1 -1.5×f pIQR ;

[0027] f pl =f pQ3 +1.5×f pIQR ;

[0028] Where: Y(f) is the sound frequency domain signal; -2jπft is a continuous periodic function; j is an imaginary unit; f p is the maximum frequency of the acoustic emission signal; f x is the frequency corresponding to the xth amplitude point in the acoustic emission signal; f p is the main frequency value of the acoustic emission signal; f pIQR is the quartile difference of the main frequency of the acoustic emission signal; f pQ1 f is the main frequency value of the acoustic emission signal corresponding to the 25% of the main frequency values ​​of the acoustic emission signal in the corresponding time period after being arranged from small to large; pQ3 f is the main frequency value of the acoustic emission signal corresponding to the 75% of the main frequency values ​​of the acoustic emission signal in the corresponding time period after being arranged from small to large; pu is the upper limit of the quartile of the main frequency of the acoustic emission signal; f pl It is the lower limit of the quartile of the main frequency of the acoustic emission signal.

[0029] Preferably, the expression for calculating the improved acoustic emission Ib value of the effective acoustic emission signal in the main frequency band based on the effective acoustic emission signal is:

[0030]

[0031] In the formula, α 1pj , α 2pj To improve the empirical parameters of acoustic emission Ib value; For amplitude greater than The cumulative amplitude of For amplitude greater than The cumulative amplitude of is the average value of the acoustic emission amplitude; A is the acoustic emission amplitude; σ A is the standard deviation of the acoustic emission amplitude.

[0032] Preferably, the statistical process of improving the acoustic emission Ib value by controlling the loading process of the structure and component in S4 includes:

[0033] Upper limit formula in statistical process control:

[0034] Ub pj =μIb pj +3σIb pj ;

[0035] The lower limit formula in statistical process control is:

[0036] LIB pj =μIb pj -3σIb pj ;

[0037] Among them, UIb pj To improve the upper limit of the statistical process control of acoustic emission Ib value; LIb pj To improve the lower limit of the statistical process control of acoustic emission Ib value; μIb pj To improve the average value of acoustic emission Ib value; σIb pj To improve the standard deviation of the acoustic emission Ib value; Ib pji is the improved acoustic emission Ib value under the i-th working condition.

[0038] Preferably, the upper limit UIb of the statistical process control is pj and the lower bound LIb pj As the damage threshold of concrete joint area, it is compared with the improved acoustic emission Ib value;

[0039] If the improved acoustic emission Ib value is less than the lower limit LIb pj Or greater than the upper limit UIb pj When , the improved acoustic emission Ib value is considered to be an abnormal value, indicating that damage begins to occur in the joint area of ​​the spliced ​​concrete components;

[0040] If the improved acoustic emission Ib value is not less than the lower limit LIb pj Or not greater than the upper limit UIb pj When , the improved acoustic emission Ib value is considered to be normal.

[0041] In summary, considering the impact of different interface connection methods on acoustic emission monitoring: the use of improved acoustic emission Ib value can reduce the impact of splicing interface and interference signals. Compared with the acoustic emission Ib value, the improved acoustic emission Ib value can more sensitively identify the initial damage moment of the concrete splicing area with different interface connection methods, thereby improving the accuracy of the initial damage warning of the concrete splicing area and effectively preventing the occurrence of damage in the splicing area of ​​spliced ​​concrete components.

[0042] The technical method of the present invention is further described in detail below through the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a step diagram of a structural splicing area damage early warning method based on an improved acoustic emission energy index value of the present invention;

[0044] Figure 2 This is the loading diagram of the spliced ​​concrete component and the arrangement diagram of the strain gauge and displacement meter of the present invention. Figure 2 (a) is a schematic diagram of loading for direct shearing. Figure 2 (b) is a physical diagram of the direct shear invention loading and the arrangement of strain gauges and displacement meters. Figure 2 (c) is a schematic diagram of the arrangement of strain gauges and displacement meters;

[0045] Figure 3 This is a layout diagram of acoustic emission sensors for splicing concrete components of the present invention. Figure 3 (a) is a schematic diagram of the acoustic emission sensor layout. Figure 3 (b) Physical diagram of the acoustic emission sensor layout;

[0046] Figure 4 The main frequency of acoustic emission during the test phase of the concrete component with roughening and splicing method under direct shearing of the present invention;

[0047] Figure 5 It is the improved acoustic emission Ib value of the roughened and spliced ​​concrete components under direct shear action of the present invention. DETAILED DESCRIPTION

[0048] The technical method of the present invention is further described below by means of the accompanying drawings and embodiments. It should be noted that unless otherwise specifically stated, the relative arrangement of the components and steps, numerical expressions and numerical values ​​described in these embodiments do not limit the scope of the present application.

[0049] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0050] Technologies, systems, and devices known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, systems, and devices should be considered part of the specification.

[0051] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0052] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0053] The present invention proposes a structural splicing area damage early warning method based on an improved acoustic emission energy index value. The effective acoustic emission signal frequency domain range is determined according to the upper and lower limits of the quartile difference of the main frequency characteristics of the acoustic emission signal, and then the effective acoustic emission signal is extracted. In addition, the empirical parameters are corrected by considering different interface connection methods. The method can reduce the influence of the splicing interface and the interference signal, and more accurately identify the initial damage of the concrete splicing area. When applied to actual projects, it can improve the accuracy of the initial damage early warning of the splicing area of ​​the prefabricated structure, and effectively prevent the occurrence of damage in the splicing area of ​​the prefabricated structure.

[0054] Embodiment 1

[0055] The present invention proposes a structural splicing area damage early warning method based on an improved acoustic emission energy index value, such as Figure 1 As shown, the method includes:

[0056] S1. Taking the acoustic emission signal of the trial sampling stage, determining the main frequency band signal under different interface connection modes according to the acoustic emission signal of the trial sampling stage;

[0057] Preferably, the specific content of determining the main frequency band signal under different interface connection modes according to the acoustic emission signal in the trial sampling stage in S1 includes:

[0058] Use fast Fourier transform FFT to calculate the acoustic emission signal in the frequency domain;

[0059] The expression of Fast Fourier Transform FFT is:

[0060]

[0061] The maximum frequency of the acoustic emission signal is obtained by the calculation formula of the main frequency of the acoustic emission signal;

[0062] The calculation formula of the main frequency of acoustic emission signal is:

[0063] f p =max|f x |;

[0064] The quartile method was used to further determine the upper and lower limits of the quartile of the main frequency of acoustic emission;

[0065] The expression of the quartile method is:

[0066] f pu =f pQ1 -1.5×f pIQR ;

[0067] f pl =f pQ3 +1.5×f pIQR ;

[0068] Where: Y(f) is the sound frequency domain signal; -2jπft is a continuous periodic function; j is an imaginary unit; f p is the maximum frequency of the acoustic emission signal; f x is the frequency corresponding to the xth amplitude point in the acoustic emission signal; f p is the main frequency value of the acoustic emission signal; f pIQR is the quartile difference of the main frequency of the acoustic emission signal; f pQ1 f is the main frequency value of the acoustic emission signal corresponding to the 25% of the main frequency values ​​of the acoustic emission signal in the corresponding time period after being arranged from small to large; pQ3 f is the main frequency value of the acoustic emission signal corresponding to the 75% of the main frequency values ​​of the acoustic emission signal in the corresponding time period after being arranged from small to large; pu is the upper limit of the quartile of the main frequency of the acoustic emission signal; f pl It is the lower limit of the quartile of the main frequency of the acoustic emission signal.

[0069] S2, using digital filtering separation method to extract effective acoustic emission signals of the main frequency band under different interface connection modes;

[0070] S3, based on the effective acoustic emission signal combined with maturity theory to calculate the improved acoustic emission Ib value of the effective acoustic emission signal in the main frequency band;

[0071] Preferably, the expression for calculating the improved acoustic emission Ib value of the effective acoustic emission signal in the main frequency band based on the effective acoustic emission signal is:

[0072]

[0073] In the formula, α 1pj , α 2pj To improve the empirical parameters of acoustic emission Ib value; For amplitude greater than The cumulative amplitude of For amplitude greater than The cumulative amplitude of is the average value of the acoustic emission amplitude; A is the acoustic emission amplitude; σ A is the standard deviation of the acoustic emission amplitude.

[0074] The acoustic emission Ib value is calculated based on the effective acoustic emission signal extracted in the test phase, and the empirical parameters in the acoustic emission Ib value calculation formula are corrected. The lead breaking invention under three different interface connection methods, namely, grooving, roughening, and rebar embedding, is carried out. Based on the acoustic emission Ib value in the concrete of the splicing area, the empirical parameters of the acoustic emission Ib value in the splicing area of ​​the concrete splicing area of ​​roughening splicing, grooving splicing, and rebar embedding splicing are improved, so that the empirical parameters of the acoustic emission Ib value in the concrete splicing area of ​​different interface connection methods are obtained as shown in Table 1.

[0075] Table 1 Empirical parameters of acoustic emission Ib values ​​in concrete joint areas

[0076]

[0077] Considering the influence of concrete joint area on the characteristics of acoustic emission Ib value, the empirical parameters of acoustic emission Ib value of concrete joint area with different splicing methods are modified, which helps to improve the accuracy of damage warning of joint area.

[0078] S4. Improve the statistical process of acoustic emission Ib value by controlling the loading process of structures and components;

[0079] By performing statistical process control on the structure / component loading process and quickly judging the damage of concrete components based on real-time feedback information, the health status of concrete components can be judged intuitively, in real time and quantitatively.

[0080] The statistical process of improving the acoustic emission Ib value by controlling the loading process of structures and components in S4 includes:

[0081] Upper limit formula in statistical process control:

[0082] Ub pj =μIb pj +3σIb pj ;

[0083] Lower limit formula in statistical process control:

[0084] LIB pj =μIb pj -3σIb pj ;

[0085] Among them, UIb pj To improve the upper limit of the statistical process control of acoustic emission Ib value; LIb pj To improve the lower limit of the statistical process control of acoustic emission Ib value; μIb pj To improve the average value of acoustic emission Ib value; σIb pj To improve the standard deviation of the acoustic emission Ib value; Ib pji is the improved acoustic emission Ib value under the i-th working condition.

[0086] S5. Provide early warning of damage to the splicing area based on the statistical process.

[0087] Preferably, the upper limit UIb of the statistical process control is pj and the lower bound LIb pj As the damage threshold of concrete joint area, it is compared with the improved acoustic emission Ib value;

[0088] If the improved acoustic emission Ib value is less than the lower limit LIb pjOr greater than the upper limit UIb pj When , the improved acoustic emission Ib value is considered to be an abnormal value, indicating that damage begins to occur in the joint area of ​​the spliced ​​concrete components;

[0089] If the improved acoustic emission Ib value is not less than the lower limit LIb pj Or not greater than the upper limit UIb pj When , the improved acoustic emission Ib value is considered to be normal.

[0090] Embodiment 2

[0091] (1) The present invention manufactures three groups of concrete components with different splicing methods, and the size of each group of components is 300mm (length) × 100mm (width) × 500mm (height). Concrete components with different splicing methods are manufactured with reference to the "Concrete Structure Engineering Construction Code". The concrete components with different splicing methods are cast twice in succession. The concrete strength of the components is C30, the average value of the measured cube compressive strength is 30.2MPa, and the elastic modulus is 2.74×105MPa. The mechanical properties of the embedded reinforcement, i.e., the material properties of the reinforcement, are shown in Table 2.

[0092] Table 2 Mechanical properties of embedded reinforcement, i.e. material properties of reinforcement

[0093]

[0094] (2) Component loading scheme and sensor layout

[0095] This invention uses a SANS microcomputer-controlled electro-hydraulic servo tension and compression machine for loading operations. Before formal loading, the component needs to be preloaded, and the force is set to 1kN during preloading. During formal loading, the load loading method is used with a loading speed of 10N / s until the component is completely destroyed. The schematic diagram of the direct shear loading of the component is as follows Figure 2 As shown. In order to analyze the change of mechanical properties of components in direct shear, the invention arranges strain gauges; in order to monitor the slip of the component joint area, the invention arranges displacement meters. The invention uses DH3817 to collect data. The strain gauges and displacement meters of the components are arranged as shown. Figure 2 The present invention arranges 9 acoustic emission sensors symmetrically on both sides of the component splicing area, such as Figure 3 shown.

[0096] (3) Component damage moment identification based on improved acoustic emission Ib value

[0097] 1) Determine the main frequency signal

[0098] According to the acoustic emission signal collected every second during the test phase of concrete components with different splicing methods under direct shear, the main frequency of the acoustic emission signal is calculated by Fourier transform FFT. The test phase lasts for 100 seconds, and the main frequency of the acoustic emission signal is calculated every second. The calculation results are as follows Figure 4 As shown. Figure 4 The quartile method of the formula is used to obtain the main frequency characteristic values ​​of acoustic emission collected by different acoustic emission sensors for concrete components with different splicing methods. The calculation results of the roughening splicing method, that is, the main frequency characteristic values ​​of acoustic emission of spliced ​​concrete components (unit: kHz), are shown in Table 3.

[0099] Table 3 Calculation results of rough chiseling method, i.e. main frequency characteristic value of acoustic emission of spliced ​​concrete components (unit: kHz)

[0100]

[0101]

[0102] 2) Extract effective acoustic emission signals

[0103] The digital filtering separation method is used to extract the effective acoustic emission signal in the main frequency band.

[0104] 3) Improved acoustic emission Ib value of effective acoustic emission signal in the main frequency band

[0105] The improved acoustic emission Ib value of concrete components with different splicing methods during the test phase is calculated based on the effective acoustic emission signal. As shown in the expression for calculating the improved acoustic emission Ib value of the effective acoustic emission signal in the main frequency band based on the effective acoustic emission signal, the loading time during the test phase is 100s, and one improved acoustic emission Ib value is calculated per second.

[0106] 4) Improve the statistical process control of acoustic emission Ib value

[0107] According to the improved acoustic emission Ib value in the component trial sampling stage and the upper limit formula in the statistical process control and the lower limit formula in the statistical process control, the upper and lower limits of the statistical process control based on the improved acoustic emission Ib value can be calculated as shown in Table 4. The upper and lower limits of the statistical process control based on the improved acoustic emission Ib value of the roughened spliced ​​concrete components are obtained as (0.65, 1.28) respectively.

[0108] Table 4 Upper and lower limits of statistical process control based on improved acoustic emission Ib value

[0109]

[0110] (4) Initial damage analysis results of concrete joint area based on improved acoustic emission Ib value

[0111] According to the effective acoustic emission signal of the main frequency band per second during the test phase and the improved acoustic emission Ib value of the roughened component, the calculation results are as follows: Figure 5The initial damage time (unit: s) of the concrete components with roughened joints identified based on the improved acoustic emission Ib value is shown in Table 5, so that the damage time is consistent with the actual concrete mutation strain value, and the identification accuracy reaches 100%.

[0112] Table 5 Identification of initial damage time of concrete components with roughened joints based on improved acoustic emission Ib value (unit: s)

[0113]

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical method of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical method to deviate from the spirit and scope of the technical method of the present invention.

Claims

1. A structural splicing area damage early warning method based on an improved acoustic emission energy index value, characterized in that: The following steps are involved: S1. Taking the acoustic emission signal of the trial sampling stage, determining the main frequency band signal under different interface connection modes according to the acoustic emission signal of the trial sampling stage; S2, using digital filtering separation method to extract effective acoustic emission signals of the main frequency band under different interface connection modes; S3, calculating the improved acoustic emission Ib value of the effective acoustic emission signal in the main frequency band based on the effective acoustic emission signal; S4. Improve the statistical process of acoustic emission Ib value by controlling the loading process of structures and components; S5. Provide early warning of damage to the splicing area based on the statistical process.

2. The structural splicing area damage early warning method based on improved acoustic emission energy index value according to claim 1 is characterized in that: The specific contents of determining the main frequency band signals under different interface connection modes according to the acoustic emission signals in the trial sampling stage in S1 include: Use fast Fourier transform FFT to calculate the acoustic emission signal in the frequency domain; The expression of Fast Fourier Transform FFT is: The maximum frequency of the acoustic emission signal is obtained by the calculation formula of the main frequency of the acoustic emission signal; The calculation formula of the main frequency of acoustic emission signal is: f p =max|f x |; The quartile method was used to further determine the upper and lower limits of the quartile of the main frequency of acoustic emission; The expression of the quartile method is: f pu =f pQ1 -1.5×f pIQR ; f pl =f pQ3 +1.5×f pIQR ; Where: Y(f) is the frequency domain signal of acoustic emission; y(t) is the time domain signal of acoustic emission; e -2jπft is a continuous periodic function; j is an imaginary unit; f p is the maximum frequency of the acoustic emission signal; f x is the frequency corresponding to the xth amplitude point in the acoustic emission signal; f p is the main frequency value of the acoustic emission signal; f pIQR is the quartile difference of the main frequency of the acoustic emission signal; f pQ1 f is the main frequency value of the acoustic emission signal corresponding to the 25% of the main frequency values ​​of the acoustic emission signal in the corresponding time period after being arranged from small to large; pQ3 f is the main frequency value of the acoustic emission signal corresponding to the 75% of the main frequency values ​​of the acoustic emission signal in the corresponding time period after being arranged from small to large; pu f is the upper limit of the quartile of the main frequency of the acoustic emission signal; pl It is the lower limit of the quartile of the main frequency of the acoustic emission signal.

3. The structural splicing area damage early warning method based on improved acoustic emission energy index value according to claim 1 is characterized in that: The expression for calculating the improved acoustic emission Ib value of the effective acoustic emission signal in the main frequency band based on the effective acoustic emission signal is: In the formula, α 1pj , α 2pj To improve the empirical parameters of acoustic emission Ib value; For amplitude greater than The cumulative amplitude of For amplitude greater than The cumulative amplitude of is the average value of the acoustic emission amplitude; A is the acoustic emission amplitude; σ A is the standard deviation of the acoustic emission amplitude.

4. The structural splicing area damage early warning method based on improved acoustic emission energy index value according to claim 1 is characterized in that: The statistical process of improving the acoustic emission Ib value by controlling the loading process of structures and components in S4 includes: Upper limit formula in statistical process control: UIb pj =μIb pj +3σIb pj ; The lower limit formula in statistical process control is: LIb pj =μIb pj -3σIb pj ; Among them, UIb pj To improve the upper limit of the statistical process control of acoustic emission Ib value; LIb pj To improve the lower limit of the statistical process control of acoustic emission Ib value; μIb pj To improve the average value of acoustic emission Ib value; σIb pj To improve the standard deviation of acoustic emission Ib value; Ib pji is the improved acoustic emission Ib value under the i-th working condition.

5. The structural splicing area damage early warning method based on improved acoustic emission energy index value according to claim 1 is characterized in that: The upper limit of statistical process control UIb pj and the lower bound LIb pj As the damage threshold of concrete joint area, it is compared with the improved acoustic emission Ib value; If the improved acoustic emission Ib value is less than the lower limit LIb pj Or greater than the upper limit UIb pj When , the improved acoustic emission Ib value is considered to be an abnormal value, indicating that damage begins to occur in the joint area of ​​the spliced ​​concrete components; If the improved acoustic emission Ib value is not less than the lower limit LIb pj Or not greater than the upper limit UIb pj When , the improved acoustic emission Ib value is considered to be normal.

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