Digital twinborn construction method for ancient city building

Abstract

The invention discloses an ancient city building digital twinning construction method, and relates to the technical field of digital twinning, and the method comprises the following steps: building a real-time 3D model of an ancient city building in a to-be-detected region based on a digital twinning model, and obtaining the structural health influence data of the ancient city building; constructing a structure health assessment model based on a bp neural network according to the structure health influence data; evaluating the structure of the ancient city building based on the structure health evaluation model, and performing structure optimization on the ancient city building according to a structure evaluation result; through the real-time data and the efficient evaluation model, the structure health state of the ancient city building is accurately evaluated, resource waste is avoided, and the service life of the building is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of digital twin technology, and more specifically, to a method for constructing a digital twin of an ancient city building. Background Art

[0002] With the rapid development of information technology, the protection and inheritance of ancient city buildings as important cultural heritages are facing unprecedented challenges and opportunities. Traditional protection methods are often limited to physical restoration and documentary records, which make it difficult to fully and dynamically display the historical features and changes of ancient city buildings. Therefore, the construction method of digital twins of ancient city buildings came into being and became an innovative protection strategy.

[0003] Digital twin technology, as an emerging digital modeling and simulation technology, collects 3D data of ancient city buildings with high precision to build a virtual model that is highly consistent with the physical building. This technology can not only accurately restore the appearance, structure, material and other details of the ancient city buildings, but also simulate the changing state of the ancient city in different historical periods and different environmental conditions.

[0004] In the process of building the digital twin of the ancient city buildings, a variety of advanced technical means were integrated, such as drone aerial photography, laser scanning, 3D modeling, texture mapping, etc. The application of these technologies has enabled the digital twin model to reach an unprecedented level in terms of accuracy, realism and interactivity.

[0005] The above disclosed technical solutions have at least the following technical problems: The traditional method of constructing digital twins of ancient city buildings still requires personnel to evaluate the completed building models after the construction is completed, and it is impossible to accurately evaluate the structural health status of the ancient city buildings in real time. In view of the above problems, the present invention proposes a solution. Summary of the invention

[0006] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a method for constructing a digital twin of an ancient city building, which uses real-time data and an efficient evaluation model to solve the problem of accurately evaluating the structural health status of ancient city buildings, avoiding waste of resources and extending the life of buildings.

[0007] To achieve the above object, the present invention provides the following technical solutions: A method for constructing digital twins of ancient city buildings, which includes constructing a real-time 3D model of the ancient city buildings in a test area based on a digital twin model, and obtaining structural health impact data of the ancient city buildings; constructing a structural health assessment model based on a BP neural network according to the structural health impact data; assessing the structure of the ancient city buildings based on the structural health assessment model, and optimizing the structure of the ancient city buildings according to the structural assessment results.

[0008] In a preferred embodiment, the structural health impact data includes environmental impact factors, and the steps for obtaining the environmental impact factors are as follows: historical meteorological data and environmental pollution data of the area to be tested are obtained, and characteristic parameters are extracted, the characteristic parameters include temperature, humidity and pollutant concentration, and the duration of the characteristic parameters is recorded, and the duration of the characteristic parameters is the duration of the environmental factor; the extracted characteristic parameters are subjected to secondary extraction to extract the maximum value of the characteristic parameters, and the extracted maximum value data are added and averaged to obtain the intensity of the characteristic parameters, that is, the intensity of the environmental factor; the building plan of the area to be tested is obtained, and the area of ​​the area affected by the environmental factor is measured through the plan; the environmental stress data of the area to be tested is obtained, and the environmental stress data includes wind speed, rainfall and acid rain concentration, and the obtained data is cleaned to delete the data changes caused by artificial rainfall; the environmental impact factor is calculated based on the preset environmental impact factor formula according to the intensity of the environmental factor, the duration of the environmental factor, the area of ​​the area affected by the environmental factor and the environmental stress data.

[0009] In a preferred embodiment, the structural health impact data includes building material decay factors, and the steps for obtaining the building material decay factors are as follows: Classify the building materials in the area to be tested, and obtain the current strength of the materials based on ultrasonic technology testing; prepare a group of new building materials as initial materials according to the types of building materials in the area to be tested, apply tension to the initial materials, and increase the tension every few seconds until cracks appear in the materials, so as to obtain the initial strength of the building materials; prepare a group of new building materials that are the same type as the building materials in the area to be tested, perform aging tests on the materials to be tested based on accelerated aging tests, and record the relationship data between the aging degree of the materials and time, analyze the relationship data between the aging degree and time based on regression analysis, and obtain the material decay rate index; obtain the number of years since the materials in the area to be tested have been put into use, that is, the service life of the materials; obtain vibration signal data in the area to be tested, analyze the frequency spectrum of the vibration signal based on Fourier transform, and identify the external load source; obtain the external load based on the frequency and amplitude of the vibration, through the relationship data with the vibration mode and natural frequency of the structure, based on the stress formula; calculate the building material decay factor based on the preset building material decay factor formula according to the current strength of the material, the initial strength of the material, the decay rate index of the material, the service life of the material and the external load.

[0010] In a preferred embodiment, the structural health impact data includes a structural stress factor, and the steps for obtaining the structural stress factor are as follows: obtain the load intensity of the building to be tested during use, the load including the weight of personnel, the weight of furniture, wind load and snow load; prepare a building structure that is the same as the building to be tested, apply different types of loads to the building structure, and the load intensity continues to increase until the structure collapses, and record the structural stress data and the maximum load when the structure collapses; according to the relationship data between the load and the structural stress, obtain the influence index of the load on the structural stress based on regression analysis; according to the floor plan of the building, obtain the area where each load acts; prepare a group of test material types, obtain the relationship data between stress and strain through a tensile test, and plot the stress and strain data into a stress-strain curve, and obtain the resistance coefficient of the structural material to stress based on the stress-strain curve based on the 0.2% offset method; calculate the structural stress factor based on the preset structural stress factor formula according to the load intensity, maximum load, the influence index of the load on the structural stress, the area where the load acts and the resistance coefficient of the structural material to stress.

[0011] In a preferred embodiment, the structure of the ancient city building is evaluated based on the structural health assessment model, and the structure of the ancient city building is optimized according to the structural assessment results, as follows: the structure of the ancient city building is evaluated based on the structural health assessment model to obtain a structural health assessment coefficient; characteristic parameters in the structural health assessment model are extracted, and the characteristic parameters include service life, current strength of the material, material decay rate index and influence coefficient of external load on material decay, and the characteristic parameters are estimated based on time series analysis; the estimated characteristic parameters are input into the structural health assessment model to obtain an estimated value, and if the estimated value is lower than a preset value, the administrator will be reminded to arrange maintenance and repair in advance.

[0012] Technical effects and advantages of the ancient city building digital twin construction method of the present invention: 1. The present invention can realize real-time monitoring of ancient city buildings through digital twin models combined with data on the structural health of ancient city buildings (such as environmental factors, building material decay factors, and structural stress factors). This monitoring is not just a static image display, but based on real-time collected data (such as historical meteorological data, environmental pollution data, building material strength, and vibration signals), a 3D model of the building is generated in real time, and a structural health assessment is performed on it. In this way, managers can understand the health status of the building structure in a timely manner, prevent possible damage, and prevent sudden structural problems.

[0013] 2. The present invention not only provides a real-time assessment of the health status of ancient city buildings, but also predicts future structural changes through a structural health assessment model. For example, based on time series analysis, characteristic parameters such as the service life of the building, material decay rate, and external load are estimated. If the assessment results show that the building has potential risks, the model can issue an early warning to remind the administrator to carry out maintenance or repair work to avoid more extensive damage or safety accidents caused by ignoring the problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural schematic diagram of a method for constructing a digital twin of an ancient city building according to the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] With the rapid development of information technology, the protection and inheritance of ancient city buildings as important cultural heritages are facing unprecedented challenges and opportunities. Traditional protection methods are often limited to physical restoration and documentary records, which make it difficult to fully and dynamically display the historical features and changes of ancient city buildings. Therefore, the construction method of digital twins of ancient city buildings came into being and became an innovative protection strategy.

[0017] Digital twin technology, as an emerging digital modeling and simulation technology, collects 3D data of ancient city buildings with high precision to build a virtual model that is highly consistent with the physical building. This technology can not only accurately restore the appearance, structure, material and other details of the ancient city buildings, but also simulate the changing state of the ancient city in different historical periods and different environmental conditions.

[0018] In the process of building the digital twin of the ancient city buildings, a variety of advanced technical means were integrated, such as drone aerial photography, laser scanning, 3D modeling, texture mapping, etc. The application of these technologies has enabled the digital twin model to reach an unprecedented level in terms of accuracy, realism and interactivity.

[0019] The traditional method of constructing digital twins of ancient city buildings still requires personnel to evaluate the completed building models after construction is completed, and it is impossible to accurately evaluate the structural health status of ancient city buildings in real time.

[0020] Embodiment 1, Figure 1 The present invention provides a method for constructing a digital twin of an ancient city building, comprising the following steps: S1, build a real-time 3D model of the ancient city buildings in the test area based on the digital twin model to obtain the structural health impact data of the ancient city buildings.

[0021] In this embodiment, the real-time 3D model of the ancient city buildings in the test area is constructed based on the digital twin model to obtain the structural health impact data of the ancient city buildings, as follows: The structural health impact data include environmental impact factors, building material decay factors and structural stress factors, as follows: Environmental impact factor, the environmental impact factor is a comprehensive evaluation indicator that aims to quantify the long-term impact of environmental conditions on building health. This factor comprehensively evaluates the degree of damage to the building structure by considering the intensity, duration and area of ​​​​the affected area of ​​​​multiple environmental factors (such as temperature, humidity, pollutant concentration, etc.), while incorporating environmental stress factors (such as wind speed, acid rain) and their weighted adjustment factors. The calculation of the environmental impact factor combines the number of types of environmental factors and the number of environmental stress factors, which can reflect the nonlinear impact of environmental factors on buildings and provide a scientific basis for the protection and restoration of ancient buildings. Through the evaluation of environmental impact factors, we can better understand and respond to the challenges brought by environmental changes to building health.

[0022] The steps for obtaining the environmental impact factors are as follows: Obtain historical meteorological data and environmental pollution data of the area to be tested, and extract characteristic parameters, which include temperature, humidity and pollutant concentration, and record the duration of the characteristic parameters, which is the duration of the environmental factors; The extracted characteristic parameters are subjected to secondary extraction to extract the maximum value of the characteristic parameters, and the extracted maximum value data are added and averaged to obtain the intensity of the characteristic parameters, that is, the intensity of the environmental factors; Obtain a building plan of the area to be measured, and measure the area affected by environmental factors through the plan; Acquire environmental stress data of the area to be tested, the environmental stress data including wind speed, rainfall and acid rain concentration, clean the acquired data and delete data changes caused by artificial rainfall; The environmental impact factor is obtained by calculating based on a preset environmental impact factor formula according to the intensity of the environmental factor, the duration of the environmental factor, the area of ​​the region affected by the environmental factor and the environmental stress data.

[0023] The calculation formula of the environmental impact factor is as follows:

[0024] In the formula, It is the environmental influencing factor. is the intensity of the kth environmental factor, is the duration of the environmental factor, is the area affected by environmental factors. It is the adjustment index of the nonlinear impact of environmental factors on building structures. is the number of environmental factors, is the number of environmental stress factors, is the environmental stress factor, It is the weighted adjustment factor of environmental stress factor.

[0025] Building material decay factor is a coefficient that comprehensively evaluates the natural decay of building materials over time and the impact of the external environment. It reflects the decay of the material itself by weighted summing the current strength and reference strength ratio of different types of materials, and taking into account the decay rate index, decay constant and service life of the material. At the same time, the factor also introduces external load factors, such as vehicle vibration, construction activities, etc., and further evaluates the acceleration of the external environment on material decay by calculating the load type and impact coefficient.

[0026] The steps for obtaining the building material decay factor are specifically as follows: Classify the building materials in the area to be tested and obtain the current strength of the materials based on ultrasonic testing; According to the types of building materials in the area to be tested, a group of new building materials are prepared as initial materials, and tension is applied to the initial materials, and the tension is continuously increased every few seconds until cracks appear in the materials, thereby obtaining the initial strength of the building materials; Prepare a group of new building materials that are the same as the building materials in the area to be tested, perform aging tests on the materials to be tested based on the accelerated aging test, and record the relationship data between the aging degree of the materials and time, and analyze the relationship data between the aging degree and time based on regression analysis to obtain the material decay rate index; Obtain the number of years since the materials in the area to be tested were put into use, that is, the service life of the materials; Obtain vibration signal data in the area to be tested, analyze the frequency spectrum of the vibration signal based on Fourier transform, and identify the external load source; According to the frequency and amplitude of vibration, the external load is obtained through the relationship data with the vibration mode and natural frequency of the structure and calculated based on the stress formula; The building material decay factor is calculated based on a preset building material decay factor formula according to the current strength of the material, the initial strength of the material, the decay rate index of the material, the service life of the material and the external load, to obtain the building material decay factor.

[0027] The calculation formula of the building material decay factor is as follows:

[0028] In the formula, is the building material decay factor, is the current strength of the ith material, is the initial strength of the ith material, is the decay rate index of the ith material, is the number of material types, is the useful life of the ith material, is the influence coefficient of external load on material decay, is the jth external load, is the number of types of total load, is the number of types of external loads.

[0029] It should be noted that the higher the building material decay factor value, the more serious the decay of the building material, and the greater the risk to the safety and durability of the building structure; conversely, the lower the building material decay factor value, the slower the decay of the building material, and the smaller the risk to the safety and durability of the building structure.

[0030] Structural stress factor is a coefficient that comprehensively evaluates the stress level of building structures. It takes into account the various loads that the building bears during use and the influence of structural stress sources. The structural stress factor calculates the strength of different loads, the ratio of the maximum load to the bearing area, and combines the load's influence index on the structural stress. It also incorporates a variety of structural stress sources and their weight coefficients, as well as the resistance coefficient and nonlinear influence coefficient of structural materials to stress, to comprehensively reflect the stress state of the building structure. This factor not only reflects the structural fatigue and deformation that the building may encounter, but also provides an important basis for evaluating the health status of the building structure, which helps to promptly discover and deal with potential structural safety issues.

[0031] The steps for obtaining the structural stress factor are specifically as follows: Obtaining the load strength of the building to be tested during use, wherein the load includes the weight of personnel, the weight of furniture, wind load and snow load; Prepare a building structure identical to the building to be tested, apply different types of loads to the building structure, and continuously increase the load intensity until the structure stops collapsing, and record the structural stress data and the maximum load when the structure collapses; According to the relationship data between load and structural stress, the influence index of load on structural stress is obtained based on regression analysis; According to the floor plan of the building, obtain the area of ​​each load action; Prepare a group of test materials, obtain the relationship between stress and strain through tensile test, and plot the stress and strain data into a stress-strain curve. According to the stress-strain curve, the resistance coefficient of the structural material to stress is obtained based on the 0.2% offset method; The structural stress factor is obtained by calculating based on a preset structural stress factor formula according to the load intensity, the maximum load, the load influence index on the structural stress, the area of ​​the load action region and the resistance coefficient of the structural material to the stress.

[0032] The calculation formula of the structural stress factor is as follows:

[0033] In the formula, is the structural stress factor, is the intensity of the kth load, is the maximum load of the kth load, is the area of ​​each load action, is the resistance coefficient of the structural material to stress, is the number of load types, is the influence index of load on structural stress, is the number of structural stress sources, is the i-th structural stress source, is the weight coefficient of the structural stress source.

[0034] S2, constructs a structural health assessment model based on the BP neural network according to the structural health impact data.

[0035] In this embodiment, the structural health assessment model is constructed based on the BP neural network according to the structural health impact data, as follows: According to the environmental impact factors, building material decay factors and structural stress factors, a structural health assessment model is constructed based on the BP neural network, as follows: The calculation formula of the structural health assessment model is as follows:

[0036] In the formula, is the structural health assessment coefficient, It is the environmental influencing factor. is the building material decay factor, is the structural stress factor, , and is the weight coefficient.

[0037] It should be noted that when the structural health assessment coefficient value is high, it means that the building structure is in a good health state and can better withstand the impact of loads, environmental changes and historical damage. As the structural health assessment coefficient value increases, the maintenance and repair needs of the building decrease; when the structural health assessment coefficient value is low, it means that the structural health of the building is poor and there may be greater safety hazards and maintenance needs.

[0038] S3, evaluate the structure of the ancient city buildings based on the structural health assessment model, and optimize the structure of the ancient city buildings according to the structural assessment results.

[0039] In this embodiment, the structure of the ancient city building is evaluated based on the structural health assessment model, and the structure of the ancient city building is optimized according to the structural assessment result, as follows: The structure of the ancient city buildings was evaluated based on the structural health assessment model to obtain the structural health assessment coefficient; Extract characteristic parameters in the structural health assessment model, including service life, current strength of the material, material decay rate index and influence coefficient of external load on material decay, and estimate the characteristic parameters based on time series analysis; The estimated characteristic parameters are input into the structural health assessment model to obtain an estimated value. If the estimated value is lower than the preset value, the administrator will be reminded to arrange maintenance and repair in advance.

[0040] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0041] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product.

[0042] Those of ordinary skill in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0043] In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0044] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0045] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for constructing a digital twin of an ancient city building, characterized in that: The steps include: Build a real-time 3D model of the ancient city buildings in the test area based on the digital twin model to obtain the structural health impact data of the ancient city buildings; According to the structural health impact data, a structural health assessment model is constructed based on the bp neural network; The structure of the ancient city buildings is evaluated based on the structural health assessment model, and the structure of the ancient city buildings is optimized according to the structural assessment results.

2. The method for constructing a digital twin of an ancient city building according to claim 1, characterized in that: The structural health impact data includes environmental impact factors, and the steps for obtaining the environmental impact factors are as follows: Obtain historical meteorological data and environmental pollution data of the area to be tested, and extract characteristic parameters, which include temperature, humidity and pollutant concentration, and record the duration of the characteristic parameters, which is the duration of the environmental factors; The extracted characteristic parameters are subjected to secondary extraction to extract the maximum value of the characteristic parameters, and the extracted maximum value data are added and averaged to obtain the intensity of the characteristic parameters, that is, the intensity of the environmental factors; Obtain a building plan of the area to be measured, and measure the area affected by environmental factors through the plan; Acquire environmental stress data of the area to be tested, the environmental stress data including wind speed, rainfall and acid rain concentration, clean the acquired data and delete data changes caused by artificial rainfall; The environmental impact factor is obtained by calculating based on a preset environmental impact factor formula according to the intensity of the environmental factor, the duration of the environmental factor, the area of ​​the region affected by the environmental factor and the environmental stress data.

3. The method for constructing a digital twin of an ancient city building according to claim 2, characterized in that: The structural health impact data includes building material decay factors, and the steps for obtaining the building material decay factors are as follows: Classify the building materials in the area to be tested and obtain the current strength of the materials based on ultrasonic testing; According to the types of building materials in the area to be tested, a group of new building materials are prepared as initial materials, and tension is applied to the initial materials, and the tension is continuously increased every few seconds until cracks appear in the materials, thereby obtaining the initial strength of the building materials; Prepare a group of new building materials that are the same as the building materials in the area to be tested, perform aging tests on the materials to be tested based on the accelerated aging test, and record the relationship data between the aging degree of the materials and time, and analyze the relationship data between the aging degree and time based on regression analysis to obtain the material decay rate index; Obtain the number of years since the materials in the area to be tested were put into use, that is, the service life of the materials; Obtain vibration signal data in the area to be tested, analyze the frequency spectrum of the vibration signal based on Fourier transform, and identify the external load source; According to the frequency and amplitude of vibration, the external load is obtained through the relationship data with the vibration mode and natural frequency of the structure and calculated based on the stress formula; The building material decay factor is calculated based on a preset building material decay factor formula according to the current strength of the material, the initial strength of the material, the decay rate index of the material, the service life of the material and the external load, to obtain the building material decay factor.

4. The method for constructing a digital twin of an ancient city building according to claim 3, characterized in that: The structural health impact data includes a structural stress factor, and the steps for obtaining the structural stress factor are as follows: Obtaining the load strength of the building to be tested during use, wherein the load includes the weight of personnel, the weight of furniture, wind load and snow load; Prepare a building structure identical to the building to be tested, apply different types of loads to the building structure, and continuously increase the load intensity until the structure stops collapsing, and record the structural stress data and the maximum load when the structure collapses; According to the relationship data between load and structural stress, the influence index of load on structural stress is obtained based on regression analysis; According to the floor plan of the building, obtain the area of ​​each load action; Prepare a group of test materials, obtain the relationship between stress and strain through tensile test, and plot the stress and strain data into a stress-strain curve. According to the stress-strain curve, the resistance coefficient of the structural material to stress is obtained based on the 0.2% offset method; The structural stress factor is obtained by calculating based on a preset structural stress factor formula according to the load intensity, the maximum load, the load influence index on the structural stress, the area of ​​the load action region and the resistance coefficient of the structural material to the stress.

5. The method for constructing a digital twin of an ancient city building according to claim 4, characterized in that: The structure of the ancient city building is evaluated based on the structural health assessment model, and the structure of the ancient city building is optimized according to the structural assessment results, as follows: The structure of the ancient city buildings was evaluated based on the structural health assessment model to obtain the structural health assessment coefficient; Extract characteristic parameters in the structural health assessment model, including service life, current strength of the material, material decay rate index and influence coefficient of external load on material decay, and estimate the characteristic parameters based on time series analysis; The estimated characteristic parameters are input into the structural health assessment model to obtain an estimated value. If the estimated value is lower than the preset value, the administrator will be reminded to arrange maintenance and repair in advance.

6. The method for constructing a digital twin of an ancient city building according to claim 5, characterized in that: The calculation formula of the environmental impact factor is as follows: In the formula, It is the environmental influencing factor. is the intensity of the kth environmental factor, is the duration of the environmental factor, is the area affected by environmental factors. It is the adjustment index of the nonlinear impact of environmental factors on building structures. is the number of environmental factors, is the number of environmental stress factors, is the environmental stress factor, It is the weighted adjustment factor of environmental stress factor.

7. The method for constructing a digital twin of an ancient city building according to claim 6, characterized in that: The calculation formula of the building material decay factor is as follows: In the formula, is the building material decay factor, is the current strength of the ith material, is the initial strength of the ith material, is the decay rate index of the ith material, is the number of material types, is the useful life of the ith material, is the influence coefficient of external load on material decay, is the jth external load, is the number of types of total load, is the number of types of external loads.

8. The method for constructing a digital twin of an ancient city building according to claim 7, characterized in that: The calculation formula of the structural stress factor is as follows: In the formula, is the structural stress factor, is the intensity of the kth load, is the maximum load of the kth load, is the area of ​​each load action, is the resistance coefficient of the structural material to stress, is the number of load types, is the influence index of load on structural stress, is the number of structural stress sources, is the i-th structural stress source, is the weight coefficient of the structural stress source.

9. The method for constructing a digital twin of an ancient city building according to claim 8, characterized in that: The structural health assessment model is constructed based on the BP neural network according to the structural health impact data, as follows: According to the environmental impact factors, building material decay factors and structural stress factors, a structural health assessment model is constructed based on the BP neural network, as follows: The calculation formula of the structural health assessment model is as follows: In the formula, is the structural health assessment coefficient, It is the environmental influencing factor. is the building material decay factor, is the structural stress factor, , and is the weight coefficient.

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