Method and device for determining ultimate bearing capacity of damaged concrete roof panel and processor

Abstract

The embodiment of the invention provides a method and device for determining the ultimate bearing capacity of a damaged concrete roof panel and a processor, and belongs to the technical field of structural engineering safety evaluation. The method comprises the steps that at least one damage feature corresponding to a target concrete roof panel after damage is obtained; acquiring the corresponding ultimate bearing capacity and at least one inherent attribute of the target concrete roof panel when the target concrete roof panel is not damaged; substituting at least one damage characteristic corresponding to the target concrete roof panel after damage and the corresponding ultimate bearing capacity and at least one inherent attribute without damage into a corresponding prediction model, and determining the corresponding ultimate bearing capacity of the target concrete roof panel after damage; wherein the damage characteristics comprise the crack width, the crack length, the exposed length of a main rib steel bar and the stripping area of a concrete protection layer; the inherent attribute comprises the plate length.

Description

Technical Field

[0001] The present invention relates to the technical field of structural engineering safety assessment, and in particular to a method, device and processor for determining the ultimate bearing capacity of a concrete roof panel after damage. Background Art

[0002] Large prestressed concrete roof panels, due to their excellent mechanical properties and suitability for long-span structures, became the standard configuration for industrial plants, warehouses, and other buildings from the 1980s to the early 21st century. However, over time, due to repeated loads, environmental erosion, and material aging, roof panels commonly develop typical damage such as cracks, exposed main ribs, and loss of the concrete cover. These damages not only affect the overall stiffness and durability of the structure but also significantly weaken its ultimate load-bearing capacity.

[0003] In recent years, with the advent of the building stock era, a large number of industrial plants and public buildings have entered the maintenance and renovation phase. Assessing the safety status of existing concrete roof panels has become a key and challenging task in building structure inspection. Traditional load-bearing capacity assessment methods rely on complex loading tests or standard static calculations. These assessment processes are time-consuming, costly, and fail to fully reflect the actual extent of damage. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a method, apparatus, processor, and computer program product for determining the ultimate bearing capacity of a damaged concrete roof panel. This method can provide a method for quantitatively evaluating the bearing capacity of existing large concrete roof panels without destroying the structure, based on apparent damage caused by long-term service, such as exposed main ribs, crack propagation, and concrete spalling.

[0005] To achieve the above-mentioned object, a first aspect of an embodiment of the present invention provides a method for determining the ultimate bearing capacity of a damaged concrete roof panel, the method comprising:

[0006] Obtaining at least one damage feature corresponding to the target concrete roof panel after damage;

[0007] Obtaining the ultimate bearing capacity and at least one inherent property of the target concrete roof panel when it is undamaged; and

[0008] Substituting at least one damage feature corresponding to the target concrete roof panel after damage, the ultimate bearing capacity corresponding to the target concrete roof panel when undamaged, and at least one inherent property into a corresponding prediction model to determine the ultimate bearing capacity corresponding to the target concrete roof panel after damage;

[0009] The damage characteristics include: crack width, crack length, exposed length of main rib steel bars and area of ​​concrete cover spalling; the inherent properties include plate length.

[0010] Preferably, the prediction model is a regression model.

[0011] Preferably, the prediction model includes:

[0012]

[0013] Among them, P0 is the ultimate bearing capacity of the concrete roof panel after damage; P u L is the ultimate bearing capacity of the concrete roof panel when it is undamaged; exp is the exposed length of the main rib reinforcement; L0 is the plate length; A is the model parameter; B is the model parameter.

[0014] Preferably, the ultimate bearing capacity P of the target concrete roof panel when it is undamaged is u , is based on the magnification factor μ and the corresponding bending bearing capacity of the target concrete roof panel when it is undamaged The identified ones include:

[0015]

[0016] Preferably, according to the following parameters corresponding to the target concrete roof panel: equivalent rectangular stress figure coefficient α1, concrete axial compressive strength f c , section width b, concrete compression zone height x and section effective height h0, determine the corresponding bending bearing capacity of the target concrete roof panel when it is undamaged

[0017]

[0018] Preferably, the prediction model is obtained by establishing training data in the following manner and training the training data using a machine learning algorithm:

[0019] Establishing a finite element model of a concrete roof panel having at least one of the damage characteristics based on multiple sets of sample data; wherein each set of the multiple sets of sample data includes: the actual ultimate bearing capacity after damage, the actual ultimate bearing capacity without damage, and at least one of the inherent properties, corresponding to the concrete roof panel having at least one of the damage characteristics;

[0020] Determining, based on the concrete roof panel finite element model, a simulated ultimate bearing capacity of the concrete roof panel having at least one of the damage characteristics when the damage characteristic is at different values; and

[0021] Training data is determined based on the simulated ultimate bearing capacity after damage and the actual ultimate bearing capacity without damage of the concrete roof panel having at least one damage feature when the damage feature is at different values, and at least one inherent property.

[0022] Preferably, each of the plurality of groups of sample data further includes: the size and concrete strength of the concrete roof panel having at least one of the damage characteristics when it is undamaged;

[0023] The step of establishing a finite element model of a concrete roof panel having at least one of the damage characteristics according to the plurality of sets of sample data includes:

[0024] The plurality of sets of sample data are grouped according to the size and concrete strength of the concrete roof slab to determine a plurality of subsets, wherein the plurality of sample data included in any subset have the same size and the same concrete strength;

[0025] For any of the subsets, establishing a finite element model of the concrete roof panel corresponding to the subset;

[0026] Determining, based on the concrete roof panel finite element model, a simulated ultimate bearing capacity corresponding to any concrete roof panel in any subset when the concrete roof panel is undamaged;

[0027] modifying the finite element model of the concrete roof panel according to the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel in any subset when undamaged, so that the difference between the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel in any subset when undamaged is within a preset error range;

[0028] adding at least one of the damage features to the modified concrete roof panel finite element model, and determining, using the concrete roof panel finite element model having the at least one of the damage features, a simulated ultimate bearing capacity corresponding to any concrete roof panel in any subset having the at least one of the damage features after damage;

[0029] The finite element model of the concrete roof panel having the at least one damage characteristic is modified based on the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel having the at least one damage characteristic in any subset after damage, so that the difference between the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel having the at least one damage characteristic in any subset after damage is within a preset range.

[0030] Preferably, the simulated ultimate bearing capacity of the concrete roof panel after damage is determined by:

[0031] The concrete roof panel finite element model uses C3D8R solid elements to simulate concrete and uses embedded reinforcement to simulate main reinforcement. By applying prestress and boundary conditions, the simulated ultimate bearing capacity of the concrete roof panel after damage is determined.

[0032] Preferably, the actual ultimate bearing capacity of the concrete roof panel having the at least one damage feature after damage is determined by:

[0033] A static loading test is performed on the concrete roof panel having the at least one damage characteristic to determine the actual ultimate bearing capacity of the concrete roof panel having the at least one damage characteristic after being damaged.

[0034] Preferably, the method further comprises:

[0035] Determining a damage coefficient based on the ultimate bearing capacity of the target concrete roof panel after damage and the ultimate bearing capacity of the target concrete roof panel without damage; and

[0036] According to the damage coefficient and the reinforcement measures corresponding to different preset damage coefficients, the reinforcement measures corresponding to the target concrete roof panel are determined.

[0037] Preferably, determining the reinforcement measures corresponding to the target concrete roof panel includes:

[0038] When the damage coefficient corresponding to the target concrete roof panel is less than or equal to 0.9, the damaged exposed portion of the main rib is wrapped with hot-rolled steel and reinforced with bolt anchoring or epoxy resin structural adhesive.

[0039] A second aspect of an embodiment of the present invention provides a device for determining the ultimate bearing capacity of a concrete roof panel after damage, comprising: a memory configured to store instructions; and a processor configured to call the instructions from the memory and implement the method for determining the ultimate bearing capacity of a concrete roof panel after damage when executing the instructions.

[0040] A third aspect of an embodiment of the present invention provides a processor for running a program, wherein the program, when run, is used to execute: the method for determining the ultimate bearing capacity of a concrete roof panel after damage.

[0041] A fourth aspect of an embodiment of the present invention provides a computer program product, comprising a computer program, which, when executed by a processor, implements the method for determining the ultimate bearing capacity of a concrete roof panel after damage.

[0042] The method for determining the ultimate bearing capacity of a damaged concrete roof panel, provided by an embodiment of the present invention, determines the ultimate bearing capacity of a target concrete roof panel after damage based on at least one damage characteristic, its ultimate bearing capacity when undamaged, and at least one inherent property. This method enables rapid, quantitative, and engineered assessment of the ultimate bearing capacity of a damaged concrete roof panel without destroying the structure, thereby improving the efficiency and accuracy of safety assessments of existing structures.

[0043] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:

[0045] Figure 1 1 is a flow chart of a method for determining the ultimate bearing capacity of a damaged concrete roof panel provided by an embodiment of the present invention;

[0046] Figure 2 It is a schematic diagram of the ultimate bearing capacity attenuation model provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.

[0048] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application are in compliance with the relevant provisions of laws and regulations. In the embodiments of this application, certain software, components, models, and other existing solutions in the industry may be mentioned. These should be considered as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of this application, but it does not mean that the applicant has or will necessarily use such solutions.

[0049] Figure 1 FIG. 1 is a flow chart of a method for determining the ultimate bearing capacity of a concrete roof panel after damage according to an embodiment of the present invention. Figure 1 As shown, the method may include:

[0050] S101, obtaining at least one damage feature corresponding to a target concrete roof panel after damage;

[0051] In some embodiments, the damage characteristics include: crack width, crack length, crack penetration depth, crack angle, exposed length of main rib reinforcement, concrete cover spalling area, and concrete cover spalling thickness.

[0052] Specifically, this embodiment of the present invention conducted an on-site survey of large concrete roof panels that had been in service for many years in industrial buildings. Combining engineering literature with test data, the study summarized several typical damage characteristics: exposed main rib reinforcement length (exposed rebar length L); main rib diagonal cracks (crack angle θ, length l, penetration depth d); concrete cover loss (area A, thickness h); and multiple damage combinations (composite failure characterization). Through standardized image acquisition and on-site measurement, the apparent damage parameter values ​​were obtained, and basic information such as location, length, and width were recorded, establishing a sample foundation for subsequent analysis.

[0053] In some embodiments, the crack width is obtained by a crack width gauge or an image recognition system; and the exposed length of the main rib steel bars (exposed length of the main rib steel bars) is measured by a steel bar locator.

[0054] S102, obtaining the ultimate bearing capacity and at least one inherent property of the target concrete roof panel when it is undamaged;

[0055] The inherent properties include the corresponding length of the concrete roof panel when it is undamaged.

[0056] In some embodiments, the ultimate bearing capacity P of the target concrete roof panel when it is undamaged is u , is based on the magnification factor μ and the corresponding bending bearing capacity of the target concrete roof panel when it is undamaged The identified ones include:

[0057]

[0058] Furthermore, according to the following parameters corresponding to the target concrete roof panel: equivalent rectangular stress figure coefficient α1, concrete axial compressive strength f c , section width b, concrete compression zone height x and section effective height h0, determine the corresponding bending bearing capacity of the target concrete roof panel when it is undamaged

[0059]

[0060] In some embodiments, the equivalent rectangular stress pattern coefficient α1 in formula (2) takes a value of 1.0.

[0061] Furthermore, for α1f in formula (2) c bx can be determined by the following formula (3):

[0062] α1f c bx=f y A S (3)

[0063] In formula (3), A S represents the cross-sectional area of ​​the tensile reinforcement, f y Represents the stress of steel bars.

[0064] It should be noted that according to the "Concrete Structure Design Standard" GB / T50010-2010, the calculation of the ultimate bearing capacity of roof panels can be divided into two categories: bending bearing capacity and shear bearing capacity. The embodiment of the present invention uses bending bearing capacity rather than shear bearing capacity to determine the ultimate bearing capacity corresponding to the target concrete roof panel when it is undamaged. This is determined according to the following analysis process.

[0065] Specifically, the calculation formulas corresponding to the bending bearing capacity of the roof panel are shown in formula (2) and formula (3).

[0066] The calculation formula for the shear bearing capacity of the roof panel is as follows:

[0067] V=V cs +V p =α cv f tk b f h0+0.05N p0

[0068] Among them, V cs Indicates the design value of concrete shear bearing capacity; V p Indicates the design value of shear bearing capacity increased by prestressing; α cv represents the shear bearing capacity coefficient of concrete; f tk Indicates the standard value of concrete tensile strength; b f Indicates the equivalent section web width; h0 indicates the effective height of the section; N p0 It represents the resultant force of the longitudinal prestressed steel bars when the normal prestress of the concrete in the calculated section is equal to zero.

[0069] According to the above formula, the bending bearing capacity of the intact roof panel with concrete strength of C30 is 6.09kN / m when subjected to bending failure. 2 , the shear bearing capacity is 11.87kN / m 2 The bending bearing capacity of the undamaged roof panel with concrete strength of C40 is 8.13kN / m 2 , the shear bearing capacity is 14.15kN / m 2 It can be seen that the calculated bending bearing capacity under different concrete strengths is always smaller than the shear bearing capacity. Therefore, the undamaged roof panel specimen should have suffered bending failure according to the calculation data results in the specification, which is consistent with the actual test phenomenon.

[0070] Since the bending bearing capacity of roof panels with concrete strength of C30 and C40 is less than the shear bearing capacity, the roof panels only involve bending failure and no shear failure. Therefore, the bending bearing capacity can be used to determine the ultimate bearing capacity of the target concrete roof panel when it is undamaged, and the bending bearing capacity can be appropriately amplified.

[0071] Furthermore, based on formula (1), according to the magnification coefficient μ and the corresponding bending bearing capacity of the target concrete roof panel when it is undamaged, Determine the ultimate bearing capacity P of the target concrete roof panel when it is undamaged u .

[0072] Specifically, the amplification factor μ in formula (1) can be set to 1.3 to achieve the bending bearing capacity The appropriate amplification of the target concrete roof panel is used to determine the corresponding bearing capacity P when it is undamaged. u .

[0073] Formula (2) is used to calculate the bending bearing capacity The equivalent rectangular stress pattern coefficient α1 can be back-calibrated using test data from C30 and C40 concrete specimens, thereby correcting the roof slab flexural capacity calculated using the formula and reducing the error between theoretical and experimental values. The equivalent rectangular stress pattern coefficient α1 essentially compensates for material nonlinearity and construction deviations, and its physical significance can be explained by the theory of effective stress redistribution in prestressed tendons.

[0074] S103: Substitute at least one damage feature corresponding to the target concrete roof panel after damage, the ultimate bearing capacity corresponding to the target concrete roof panel when undamaged, and at least one inherent property into a corresponding prediction model to determine the ultimate bearing capacity corresponding to the target concrete roof panel after damage.

[0075] In some embodiments, the prediction model is a regression model.

[0076] Specifically, for the exposed damage of main rib steel bars, the ultimate bearing capacity attenuation model is established through regression analysis, that is, the ultimate bearing capacity calculation formula of the roof panel under the damaged state. exp / L0 is the independent variable, and a negative exponential function is used to describe the degradation law of ultimate bearing capacity.

[0077] Furthermore, Figure 2 is a schematic diagram of the ultimate bearing capacity attenuation model provided by an embodiment of the present invention, referring to Figure 2 , the ultimate bearing capacity attenuation model includes:

[0078]

[0079] Among them, P0 is the ultimate bearing capacity of the concrete roof panel after damage; P u L is the ultimate bearing capacity of the concrete roof panel when it is undamaged; exp is the exposed length of the main rib reinforcement; L0 is the corresponding length of the concrete roof panel when it is undamaged; A is the model parameter; B is the model parameter.

[0080] In some embodiments, formula (1) and formula (2) are substituted into formula (4) to further obtain formula (5):

[0081]

[0082] In formula (5), P0 is the ultimate bearing capacity of the concrete roof panel after damage; μ is the amplification factor; A is the model parameter; B is the model parameter; L exp is the exposed length of the main rib reinforcement; L0 is the plate length; α1 represents the equivalent rectangular stress figure coefficient; f c represents the axial compressive strength of concrete; b represents the section width; x represents the height of the concrete compression zone; h0 represents the effective height of the section.

[0083] In some embodiments, for roof panels with damaged surface, the corresponding damage feature is the damaged area of ​​the roof panel. Through regression analysis, a bearing capacity attenuation model is established, i.e., the ultimate bearing capacity calculation formula (6) of the roof panel under damaged state. The model uses the damaged area ratio S exp / S is the independent variable, and the negative exponential function is used to describe the degradation law of the ultimate bearing capacity:

[0084]

[0085] In formula (6), P0 is the ultimate bearing capacity of the concrete roof panel after damage, P u is the ultimate bearing capacity of the concrete roof panel when it is undamaged, S exp is the damaged area, S is the area of ​​the concrete roof panel in the undamaged state, and γ is the regression coefficient.

[0086] Substituting formulas (1) and (2) into formula (6), we can further obtain formula (7):

[0087]

[0088] In formula (7), μ is the magnification coefficient, which can be 1.3; α1 represents the equivalent rectangular stress pattern coefficient; f c represents the axial compressive strength of concrete; b represents the section width; x represents the height of the concrete compression zone; h0 represents the effective height of the section.

[0089] The embodiments of the present invention establish a quantitative relationship between the apparent damage state of a structure and its residual bearing capacity, and then combine it with field investigation, physical testing and finite element analysis to achieve efficient and non-destructive structural safety assessment.

[0090] In some embodiments, the prediction model is obtained by establishing training data according to steps S201 to S203 and training the training data using a machine learning algorithm:

[0091] S201. Establishing a finite element model of a concrete roof panel having at least one of the damage characteristics according to multiple groups of sample data;

[0092] Each of the plurality of groups of sample data includes: the actual ultimate bearing capacity after damage and the actual ultimate bearing capacity without damage and at least one of the inherent properties corresponding to the concrete roof panel having at least one of the damage characteristics;

[0093] In some embodiments, each of the plurality of groups of sample data further includes: the size and concrete strength of the concrete roof panel having at least one of the damage characteristics when it is undamaged;

[0094] The step of establishing a finite element model of a concrete roof panel having at least one damage feature according to multiple groups of sample data includes: S301 to S306.

[0095] S301, grouping the multiple sets of sample data according to the size and concrete strength of the concrete roof panel to determine multiple subsets, wherein the multiple sample data included in any subset have the same size and the same concrete strength;

[0096] Specifically, in some embodiments, a subset corresponding to the multiple groups of sample data is three large prestressed reinforced concrete roof panels with a size of 1.5m×6.0m and a concrete strength of C30, named BF-01, BF-02 and BF-03, all of which are from the converter workshop of a steelmaking plant of a certain steel company.

[0097] Among them, the damage type of BF-01, BF-02 and BF-03 is exposed main rib reinforcement damage. The corresponding plate length of BF-01, BF-02 and BF-03 when they are not damaged is 6m; the exposed main rib reinforcement lengths of BF-01, BF-02 and BF-03 are 4.5m, 3.0m and 1.5m, respectively.

[0098] It should be noted that the actual ultimate bearing capacities of BF-01, BF-02, and BF-03 when they are undamaged can be determined according to formulas (1) and (2).

[0099] S302: For any of the subsets, establish a finite element model of the concrete roof panel corresponding to the subset;

[0100] Specifically, the finite element analysis platform ABAQUS can be used to establish a finite element model of the concrete roof panel with the same proportions as the test specimens BF-01, BF-02 and BF-03.

[0101] Furthermore, the concrete roof panel finite element model has the following characteristics: the concrete adopts the CDP model; the steel bars are embedded truss units, and the elastic-plastic constitutive model is set; cracks are simulated by weak surface interpolation, and the exposed steel bar area is simulated by reducing the boundary constraints to simulate failure; the grid size is 10 cm, and the total number of control units is more than 12,000.

[0102] S303, determining, based on the concrete roof panel finite element model, a simulated ultimate bearing capacity corresponding to any concrete roof panel in any subset when the concrete roof panel is undamaged;

[0103] S304: modifying the finite element model of the concrete roof panel according to the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel in any subset when undamaged, so that the difference between the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel in any subset when undamaged is within a preset error range;

[0104] It should be noted that for S303 to S304, no damage features were added to the finite element model of the concrete roof panel.

[0105] Furthermore, by comparing the numerical differences between the actual ultimate bearing capacity and the simulated ultimate bearing capacity corresponding to the test specimens BF-01, BF-02 and BF-03 when they were undamaged, the finite element model of the concrete roof panel was modified accordingly so that the numerical differences between the actual ultimate bearing capacity and the simulated ultimate bearing capacity corresponding to the test specimens BF-01, BF-02 and BF-03 when they were undamaged were within the preset prediction range.

[0106] S305: adding at least one damage feature to the modified concrete roof panel finite element model, and determining a simulated ultimate bearing capacity corresponding to any concrete roof panel in any subset having the at least one damage feature after damage using the concrete roof panel finite element model having the at least one damage feature;

[0107] Furthermore, the implementation process of determining the actual ultimate bearing capacity corresponding to the test specimens BF-01, BF-02 and BF-03 after damage is specifically described.

[0108] Uniformly distributed static loading tests were conducted on test specimens BF-01, BF-02, and BF-03. The true load-bearing performance data of each roof panel was extracted through the load-deflection curve, cracking load, yield load, and ultimate failure state records. The actual ultimate load-bearing capacity corresponding to the failure characteristics of each component was also recorded. The test results are shown in Table 1 below:

[0109] Table 1 Failure mode and maximum failure load of concrete roof panel specimens

[0110]

[0111] It should be noted that the failure load in Table 1 is the actual ultimate bearing capacity of the test specimens BF-01, BF-02 and BF-03 after damage.

[0112] Furthermore, the implementation process of determining the simulated ultimate bearing capacity corresponding to the test specimens BF-01, BF-02 and BF-03 after damage is specifically described.

[0113] The exposed length of the main rib reinforcement was added to the revised finite element model of the concrete roof panel, and the corresponding value of the exposed length of the main rib reinforcement was adjusted. Furthermore, the exposed length of the main rib reinforcement was adjusted to 4.5 m, 3.0 m, and 1.5 m, respectively, to correspond to the test specimens BF-01, BF-02, and BF-03.

[0114] The finite element model of the concrete roof panel with exposed main rib reinforcement was added. C3D8R solid elements were used to simulate concrete, embedded reinforcement was used to simulate the main reinforcement, and prestressing and boundary conditions were applied. Finally, the stress-strain field, deformation mode and simulated ultimate bearing capacity corresponding to the test specimens BF-01, BF-02 and BF-03 were obtained.

[0115] It should be noted that by adding different damage characteristics to the finite element model of the concrete roof panel, the influence of different damage characteristics on the mechanical performance of the roof panel can be simulated. By analyzing the bearing capacity and stress field distribution obtained by simulation, the simulated ultimate bearing capacity of the concrete roof panel after damage corresponding to different damage characteristics (such as exposed reinforcement position and crack angle) can be determined.

[0116] The loading method and constraint conditions corresponding to the concrete roof panel finite element model include: adopting a double simply supported setting; applying a uniformly distributed load vertically; and simultaneously recording the deflection, crack development, and steel bar yield point.

[0117] S306. Modify the finite element model of the concrete roof panel having the at least one damage characteristic based on the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel having the at least one damage characteristic in any subset after damage, so that the difference between the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel having the at least one damage characteristic in any subset after damage is within a preset range.

[0118] Specifically, by comparing the numerical differences between the actual and simulated ultimate bearing capacities of the test specimens BF-01, BF-02, and BF-03 after damage, the finite element model of the concrete roof slab with the exposed length of the main rib reinforcement was modified accordingly, so that the numerical differences between the actual and simulated ultimate bearing capacities of the test specimens BF-01, BF-02, and BF-03 after damage were within the preset prediction range.

[0119] In some embodiments, ABAQUS is used to perform numerical simulations on the damage conditions in Table 1 to analyze the damage influence mechanism and structural response law.

[0120] S202. Determine, based on the concrete roof panel finite element model, a simulated ultimate bearing capacity of the concrete roof panel having at least one damage characteristic when the damage characteristic is at different values.

[0121] S203: Determine training data based on the simulated ultimate bearing capacity after damage and the actual ultimate bearing capacity without damage of the concrete roof panel having at least one damage feature when the damage feature is at different values, and at least one inherent attribute.

[0122] The embodiment of the present invention utilizes a finite element model of a concrete roof panel, firstly generates an actual ultimate bearing capacity and a simulated ultimate bearing capacity corresponding to the concrete roof panel in sample data before damage, and performs a first correction on the finite element model of the concrete roof panel based on the actual ultimate bearing capacity and the simulated ultimate bearing capacity corresponding to the concrete roof panel in the sample data before damage; then generates an actual ultimate bearing capacity and a simulated ultimate bearing capacity corresponding to the concrete roof panel in the sample data after damage; and further corrects the finite element model of the concrete roof panel based on the actual ultimate bearing capacity and the simulated ultimate bearing capacity corresponding to the concrete roof panel in the sample data after damage, which can improve the data accuracy of the simulated ultimate bearing capacity before and after damage generated by the finite element model of the concrete roof panel, thereby quickly generating a large amount of training data, and further improving the generalization ability of the model.

[0123] In some embodiments, the magnification factor μ=1.3; the model parameters A=1 and B=0.17633 obtained through model training are substituted into formula (5), and the obtained result is:

[0124]

[0125] The theoretical ultimate bearing capacity P0 of the test specimens BF-01, BF-02 and BF-03 after damage calculated by formula (8) is different from the actual ultimate bearing capacity P0 after damage obtained through physical testing. t Data comparison results are shown in Table 2. Table 2 shows that the error between the theoretical and actual ultimate bearing capacities of damaged specimens BF-01, BF-02, and BF-03 is less than 4%. Therefore, the method for determining the ultimate bearing capacity of damaged concrete roof panels provided by the present invention can accurately predict the ultimate bearing capacity of large prestressed concrete roof panels whose initial damage type is the exposed length of the main rib reinforcement.

[0126] Table 2 Ratio of theoretical value to actual value

[0127]

[0128] In some embodiments, the method further comprises: determining a damage coefficient according to the ultimate bearing capacity of the target concrete roof panel after damage and the ultimate bearing capacity when the target concrete roof panel is undamaged; and

[0129] According to the damage coefficient and the reinforcement measures corresponding to different preset damage coefficients, the reinforcement measures corresponding to the target concrete roof panel are determined.

[0130] Specifically, P0 / P u Defined as the damage coefficient K, it is used as another reference value and incorporated into the standard as the basis for rating. This provides the ultimate bearing capacity rating principle for roof panels in a damaged state. When K is 1.0, the component is rated as Class A; when 1.0 > K ≥ 0.90, it is rated as Class B; when 0.9 > K ≥ 0.85, it is rated as Class C; and when K < 0.85, it is rated as Class D.

[0131] Based on the above evaluation method, the damage coefficient K of BF-01, BF-02 and BF-03 roof panels is calculated. The calculation results are shown in Table 3.

[0132] Table 3 Damage coefficient K of ultimate bearing capacity of damaged roof panels

[0133]

[0134] The calculated damage coefficient K of each roof panel specimen is graded, and the ultimate bearing capacity item grade of each roof panel is obtained as shown in Table 4.

[0135] Table 4 Damage coefficient K of ultimate bearing capacity of damaged roof panels

[0136]

[0137] According to the Industrial Building Reliability Assessment Standard (GB50144-2019), the exposed rebar damage in BF-01, BF-02, and BF-03 all received a Class C rating. However, using the revised calculation method, specimens BF-01 (K = 0.87) and BF-02 (K = 0.91), with exposed main rib length ratios of 0.75 and 0.5, respectively, were quantitatively rated Class C and Class B. This result highlights the quantitative method's ability to discern subtle differences in damage severity and reflects the difference in bearing capacity between the two. Specimen BF-03, with an exposed length ratio of only 25%, was directly rated Class C under the standard assessment method due to the presence of exposed rebar. However, the revised method, through quantitative calculation, determined that its bearing capacity retained 96%, rationally raising it to Class B, thus reducing unnecessary maintenance interventions.

[0138] Furthermore, based on the roof panel bearing capacity assessment results and damage characteristics, combined with the "Code for Design of Reinforcement of Concrete Structures" (GB 50367-2013) and engineering practice experience, the following structural reinforcement suggestions are proposed to improve the safety and durability of roof panels:

[0139] For concrete roof panels with exposed main rib reinforcement, the corresponding reinforcement measures are as follows:

[0140] External steel reinforcement method: For main rib reinforcement with large exposed length (such as L exp For roof panels with a damage coefficient (K) of 0.5 or less (L0 ≥ 0.5), hot-rolled steel can be used to wrap the damaged, exposed areas of the main ribs and reinforced with bolt anchors or epoxy resin structural adhesive to increase bending stiffness and bearing capacity. This method is suitable for components with a damage coefficient of K ≤ 0.9 (Class C or D).

[0141] FRP laminated interface strengthening technology: for local exposed reinforcement (L exp For roof panels rated as Class B with a damage coefficient K ≥ 0.85, carbon fiber cloth can be pasted along the longitudinal direction of the main ribs to compensate for the loss of section stiffness by improving the tensile properties of the tensile zone. The density of the interface between the fiber and the matrix must be ensured during construction.

[0142] An embodiment of the present invention also provides a device for determining the ultimate bearing capacity of a concrete roof panel after damage, comprising: a memory configured to store instructions; and a processor configured to call the instructions from the memory and implement the method for determining the ultimate bearing capacity of a concrete roof panel after damage when executing the instructions.

[0143] An embodiment of the present invention further provides a processor for running a program, wherein the program, when run, is used to execute: the method for determining the ultimate bearing capacity of a concrete roof panel after damage.

[0144] An embodiment of the present invention further provides a computer program product, including a computer program, which, when executed by a processor, implements the method for determining the ultimate bearing capacity of a concrete roof panel after damage.

[0145] The method for determining the ultimate bearing capacity of a damaged concrete roof panel, provided by an embodiment of the present invention, determines the ultimate bearing capacity of a target concrete roof panel after damage based on at least one damage characteristic associated with the panel after damage, its ultimate bearing capacity when undamaged, and at least one inherent property. This method enables rapid, quantitative, and engineering-based bearing capacity assessment without destroying the structure. It is suitable for safety surveys, reinforcement priority sorting, and lifecycle management of large quantities of existing concrete roof panels, demonstrating its practicality and potential for widespread adoption.

[0146] The method for determining the ultimate bearing capacity of a damaged concrete roof panel provided by the embodiment of the present invention also has the following significant advantages and technical effects:

[0147] ① Non-destructive and efficient: Relying on apparent damage data and numerical models, it eliminates the need to apply actual loads to the structure on-site, thus avoiding the tedious process of loading tests and the disturbance to the structure itself. The assessment process is fast and is particularly suitable for the general diagnosis of large quantities of existing components.

[0148] ② Quantifying the damage-performance relationship: A regression model was constructed using measured and simulated data to clearly establish the functional relationship between key damage parameters such as the exposed main rib length and crack width and the ultimate bearing capacity. This achieved a scientific transformation from "apparent damage" to "residual performance" and overcame the problems of subjective judgment and empirical bias in traditional methods.

[0149] ③ Strong adaptability and promotion: Damage parameters are all visual indicators (such as cracks and exposed reinforcement), which are easy to measure; the evaluation model can be modified and expanded according to different roof panel sections, reinforcement methods, and material grades, and has good adaptability and engineering promotion potential.

[0150] ④ Assisted reinforcement and design decision-making: The method for determining the ultimate bearing capacity of a concrete roof panel after damage provided by the embodiment of the present invention can not only quantitatively evaluate the current state of the structure, but also provide a basis for subsequent reinforcement design. For example, the evaluation results can be used to determine whether reinforcement is needed, what reinforcement level to adopt, and what reinforcement method to choose, thereby providing technical support for structural lifecycle management.

[0151] ⑤ Promote the standardization of structural assessment technology: The introduction of the "damage coefficient K" will help promote the existing structural assessment methods from qualitative to quantitative, and lay the theoretical and technical foundation for the formulation of unified assessment standards and intelligent diagnosis platforms.

[0152] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0153] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0154] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0155] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0156] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0157] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0158] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0159] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0160] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for determining the ultimate bearing capacity of a damaged concrete roof panel, characterized in that: The method comprises: Obtaining at least one damage feature corresponding to the target concrete roof panel after damage; Obtaining the ultimate bearing capacity and at least one inherent property of the target concrete roof panel when it is undamaged; and Substituting at least one damage feature corresponding to the target concrete roof panel after damage, the ultimate bearing capacity corresponding to the target concrete roof panel when undamaged, and at least one inherent property into a corresponding prediction model to determine the ultimate bearing capacity corresponding to the target concrete roof panel after damage; The damage characteristics include: crack width, crack length, exposed length of main rib steel bars and area of ​​concrete cover spalling; the inherent properties include plate length.

2. The method according to claim 1, characterized in that The prediction model is a regression model.

3. The method according to claim 1, characterized in that The prediction model includes: Among them, P o is the ultimate bearing capacity of the concrete roof panel after damage; P u L is the ultimate bearing capacity of the concrete roof panel when it is undamaged; exp is the exposed length of the main rib reinforcement; L0 is the plate length; A is the model parameter; B is the model parameter.

4. The method according to claim 1, wherein The ultimate bearing capacity P of the target concrete roof panel when it is undamaged u , is based on the magnification factor μ and the corresponding bending bearing capacity of the target concrete roof panel when it is undamaged The identified ones include:

5. The method according to claim 4, characterized in that According to the following parameters corresponding to the target concrete roof panel: equivalent rectangular stress figure coefficient α1, concrete axial compressive strength f c , section width b, concrete compression zone height x and section effective height h0, determine the corresponding bending bearing capacity of the target concrete roof panel when it is undamaged 6. The method according to claim 1, characterized in that The prediction model is obtained by establishing training data in the following manner and training the training data using a machine learning algorithm: Establishing a finite element model of a concrete roof panel having at least one of the damage characteristics based on multiple sets of sample data; wherein each set of the multiple sets of sample data includes: the actual ultimate bearing capacity after damage, the actual ultimate bearing capacity without damage, and at least one of the inherent properties, corresponding to the concrete roof panel having at least one of the damage characteristics; Determining, based on the concrete roof panel finite element model, a simulated ultimate bearing capacity of the concrete roof panel having at least one of the damage characteristics when the damage characteristic is at different values; and Training data is determined based on the simulated ultimate bearing capacity after damage and the actual ultimate bearing capacity without damage of the concrete roof panel having at least one damage feature when the damage feature is at different values, and at least one inherent property.

7. The method according to claim 6, characterized in that Each of the plurality of groups of sample data further includes: the size and concrete strength of the concrete roof panel having at least one of the damage characteristics when it is undamaged; The step of establishing a finite element model of a concrete roof panel having at least one of the damage characteristics according to the plurality of sets of sample data includes: According to the size and concrete strength of the concrete roof slab, the plurality of groups of sample data are grouped to determine a plurality of subsets, wherein the plurality of sample data included in any subset have the same size and the same concrete strength; For any of the subsets, establishing a finite element model of the concrete roof panel corresponding to the subset; Determining, based on the concrete roof panel finite element model, a simulated ultimate bearing capacity corresponding to any concrete roof panel in any subset when the concrete roof panel is undamaged; modifying the finite element model of the concrete roof panel according to the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel in any subset when undamaged, so that the difference between the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel in any subset when undamaged is within a preset error range; adding at least one of the damage features to the modified concrete roof panel finite element model, and determining, using the concrete roof panel finite element model having the at least one of the damage features, a simulated ultimate bearing capacity corresponding to any concrete roof panel in any subset having the at least one of the damage features after damage; The finite element model of the concrete roof panel having the at least one damage characteristic is modified based on the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel having the at least one damage characteristic in any subset after damage, so that the difference between the simulated ultimate bearing capacity and the actual ultimate bearing capacity corresponding to any concrete roof panel having the at least one damage characteristic in any subset after damage is within a preset range.

8. The method according to claim 6, characterized in that The simulated ultimate bearing capacity of the concrete roof panel after damage is determined by the following method: The concrete roof panel finite element model uses C3D8R solid elements to simulate concrete and uses embedded reinforcement to simulate main reinforcement. By applying prestress and boundary conditions, the simulated ultimate bearing capacity of the concrete roof panel after damage is determined.

9. The method according to claim 6, characterized in that The actual ultimate bearing capacity of the concrete roof panel having the at least one damage characteristic after damage is determined by: A static loading test is performed on the concrete roof panel having the at least one damage characteristic to determine the actual ultimate bearing capacity of the concrete roof panel having the at least one damage characteristic after being damaged.

10. The method according to claim 1, characterized in that The method further comprises: Determining a damage coefficient based on the ultimate bearing capacity of the target concrete roof panel after damage and the ultimate bearing capacity of the target concrete roof panel without damage; and According to the damage coefficient and the reinforcement measures corresponding to different preset damage coefficients, the reinforcement measures corresponding to the target concrete roof panel are determined.

11. The method according to claim 10, characterized in that Determining the reinforcement measures corresponding to the target concrete roof panel includes: When the damage coefficient corresponding to the target concrete roof panel is less than or equal to 0.9, the damaged exposed portion of the main rib is wrapped with hot-rolled steel and reinforced with bolt anchoring or epoxy resin structural adhesive.

12. A device for determining the ultimate bearing capacity of a damaged concrete roof panel, characterized in that: include: a memory configured to store instructions; and a processor configured to call the instructions from the memory and implement the method for determining the ultimate bearing capacity of a concrete roof panel after damage according to any one of claims 1 to 11 when executing the instructions.

13. A processor, characterized in that: Used to run a program, wherein the program is used to execute: the method for determining the ultimate bearing capacity of a concrete roof panel after damage according to any one of claims 1 to 11 when being run.

14. A computer program product, characterized in that The invention comprises a computer program, which, when executed by a processor, implements the method for determining the ultimate bearing capacity of a concrete roof panel after damage according to any one of claims 1 to 11.

Images