A bridge cracking analysis method and system based on extended finite element theory

Abstract

The application provides a bridge cracking analysis method and system based on an extended finite element theory, and the method comprises the following steps: creating a finite element model of a whole bridge; determining a most unfavorable beam section by considering stress conditions of the bridge structure under different temperature changes, different system combinations and different operation years; expanding the range of the most unfavorable beam section and establishing a local model of the most unfavorable beam section of the bridge; and performing cracking analysis on the local model of the most unfavorable beam section based on the extended finite element theory, calculating local stress of the bridge, and analyzing crack generation and expansion. The application considers possible cracking conditions of the bridge under different temperature actions, prestress loss, shrinkage and creep effects and other factors, and reasonably adjusts and improves parameters of the whole bridge model of the bridge after considering the influences of the above factors, so that the influences of multiple factors on the generation and expansion of the cracking of the bridge are comprehensively considered, and the accuracy of the generation and expansion analysis of the cracking of the bridge is improved.

Description

Technical Field

[0001] This invention belongs to the field of bridge structural safety, specifically relating to a bridge cracking analysis method and system based on extended finite element theory. Background Technology

[0002] Concrete, due to its high compressive strength, is widely used in various water conservancy projects, buildings, bridges, and other structures. However, concrete has low tensile strength and is prone to cracking during service. Cracks are a type of bridge defect that persists throughout the construction and operation of bridges. The initiation and propagation of cracks can reduce the load-bearing capacity of the bridge structure, accelerate the erosion of steel bars and concrete by harsh environments, and endanger the normal use and safety of the bridge. At the same time, the appearance of cracks can increase the deflection of the bridge, affecting its overall aesthetics.

[0003] Concrete operates in a complex environment, and concrete cracks take many forms, including common types such as load cracks, temperature cracks, shrinkage cracks, and creep cracks. Early research on concrete cracks primarily focused on engineering examples, such as cracks in concrete structures caused by the heat of hydration during the construction of large-volume concrete structures. However, with the rapid development of prestressing technology both domestically and internationally, structural cracks in prestressed concrete bridges have become increasingly common, leading scholars to recognize the numerous factors influencing concrete cracking in bridges. Simultaneously, significant advancements in computer technology have led to the increasing maturity of numerical simulation-assisted engineering analysis. Based on the finite element method, numerical calculations and graphical representations are used to study both engineering and physical problems. Numerical simulation not only offers shorter research cycles and lower costs but is also relatively safer.

[0004] In summary, bridge structures are susceptible to multiple adverse factors and potential initial defects, leading to cracks or increased bridge deflection, which can jeopardize bridge safety. Therefore, it is essential to analyze the stress on bridge structures and the generation and propagation of concrete cracks.

[0005] CN106055784A discloses a method for evaluating fatigue crack propagation in steel bridge details. It considers the influence of vehicle type, axle load, wheelbase, lanes, the distribution ratio of each vehicle type in lanes, and temperature on crack propagation. However, it analyzes the crack propagation of bridges that have already developed cracks, without studying the causes of crack formation. Crack formation may also be affected by prestress loss, shrinkage and creep effects, model parameters, and other factors. Therefore, it is necessary to provide a new analysis scheme that can effectively analyze the generation and propagation of cracks and comprehensively consider various adverse factors affecting the bridge. Summary of the Invention

[0006] In view of this, the present invention proposes a bridge cracking analysis method and system based on extended finite element theory to solve the problem that existing bridge cracking analyses do not comprehensively consider the various adverse factors affecting the bridge.

[0007] In a first aspect, this invention discloses a method for analyzing bridge cracking based on extended finite element theory, the method comprising:

[0008] Create a finite element model of the entire bridge;

[0009] Considering the stress conditions of the bridge structure under different temperature changes, different coefficient combinations, and different service years, the most unfavorable beam segment is determined.

[0010] Expand the scope of the most unfavorable beam segment and establish a local model of the most unfavorable beam segment of the bridge;

[0011] Based on the extended finite element method, a cracking analysis was performed on a local model of the most unfavorable beam segment. The local stress of the bridge was calculated, and the crack generation and propagation were analyzed.

[0012] Based on the above technical solutions, preferably, the stress conditions of the bridge structure under different temperature changes, different coefficient combinations, and different service years specifically include:

[0013] Considering the changes in the first principal stress at three different locations—the top plate, bottom plate, and web plate—of the main beam under different temperature changes, the influence of different degrees of temperature on the cracking trend of the bridge is determined.

[0014] The stress conditions of the bridge structure were tested under different combinations of the pipe wall friction coefficient μ and the influence coefficient k of pipe deviation on friction, and the optimal combination of the pipe wall friction coefficient μ and the influence coefficient k of pipe deviation on friction was determined under the condition of cracking tendency.

[0015] Test the stress changes of various structural components of the bridge under different years of operation;

[0016] Based on the influence of different degrees of overall temperature on the cracking tendency of the bridge, the optimal combination of the pipe wall friction coefficient μ and the influence coefficient k of pipe deviation on friction, and the stress changes of various parts of the bridge structure under different service years, the beam segments with cracking tendency are identified and the beam segments with cracking tendency are identified as the most unfavorable beam segments.

[0017] Based on the above technical solutions, preferably, the consideration of the changes in the first principal stress at three different locations—the top plate, bottom plate, and web plate of the main beam—under different temperature changes, and the determination of the influence of different degrees of temperature on the cracking trend of the bridge, specifically includes:

[0018] The effects of gradient heating, gradient cooling, and different degrees of overall temperature change on the cracking trend of the bridge are determined by considering the changes in the first principal stress at three different locations of the main beam: the top plate, the bottom plate, and the web plate.

[0019] Based on the above technical solutions, preferably, in the different combinations of coefficients, the values ​​of the pipe wall friction coefficient μ and the influence coefficient k of the pipe deviation on friction both show an increasing trend.

[0020] Based on the above technical solutions, preferably, expanding the range of the most unfavorable beam segment and establishing a local model of the most unfavorable beam segment of the bridge specifically includes:

[0021] Identify the unfavorable region near the most unfavorable beam segment;

[0022] Expand the range of the most unfavorable beam segment based on the unfavorable region near the most unfavorable beam segment to obtain the unfavorable beam segment, and build the geometric model of the unfavorable beam segment in Revit software;

[0023] The geometric model of the unfavorable beam segment is imported into Hypermesh software, a finite element mesh is generated, and the solid model of the unfavorable beam segment is obtained.

[0024] The solid model of the unfavorable beam segment is imported into the ABAQUS finite element calculation software as a component to obtain the local model of the unfavorable beam segment.

[0025] Based on the above technical solutions, preferably, the step of performing crack analysis on the local model of the most unfavorable beam segment based on extended finite element theory, calculating the local stress of the bridge, and analyzing the crack generation and propagation specifically includes:

[0026] Based on the extended finite element theory, precast cracks are embedded at appropriate locations in the local model of the unfavorable beam segment. The maximum principal stress traction cracking criterion for C55 concrete is set, and the fracture energy of C55 concrete is input into the model.

[0027] Extract the stress boundary of the most unfavorable beam segment under the most unfavorable working condition, apply the extracted stress boundary to the local model of the unfavorable beam segment, and at the same time consider the load on the local beam segment itself to simulate and analyze the stress situation of the local beam segment under the most unfavorable working condition.

[0028] PHILSM contour plots of the unfavorable beam segment at different stages were obtained to observe the cracking situation of the beam segment.

[0029] Based on the above technical solutions, the preferred bridge is the Yunnan Zhuang Grand Bridge, and the most unfavorable beam segments are the upper chord S4 beam segment and the mid-span No. 33 beam segment.

[0030] In a second aspect, this invention discloses a bridge cracking analysis system based on the extended finite element theory, the system comprising:

[0031] Full Bridge Model Creation Module: Used to create a finite element model of the entire bridge.

[0032] The module for determining the most unfavorable beam segment is used to consider the stress conditions of bridge structures under different temperature changes, different combinations of coefficients, and different service years, and to determine the most unfavorable working conditions; and to determine the most unfavorable beam segment under the most unfavorable working conditions.

[0033] Local model building module: used to expand the scope of the most unfavorable beam segment and build a local model of the most unfavorable beam segment of the bridge;

[0034] Beam segment cracking analysis module: Based on the extended finite element theory, cracking analysis is performed on the local model of the most unfavorable beam segment, and the local stress of the bridge and the initiation and propagation of cracks are calculated.

[0035] The present invention has the following advantages over the prior art:

[0036] 1) This invention considers the possible cracking of bridges under different temperature effects, prestress loss, and shrinkage and creep effects, and makes reasonable adjustments and improvements to the parameters of the full bridge model after considering the influence of the above factors. It comprehensively considers the role of multiple factors in the generation and propagation of bridge cracks, improves the accuracy of analysis on the generation and propagation of bridge cracks, and can be used to simulate the location and propagation direction of bridge cracks.

[0037] 2) This invention analyzes the most unfavorable conditions for bridge cracking based on the optimal combination of the overall temperature effect on the cracking trend of bridges, the friction coefficient μ of pipe walls and the influence coefficient k of pipe deviation on friction, and the stress changes of various parts of the bridge structure under different operating years. It also identifies the most unfavorable beam segment under the most unfavorable conditions and establishes a local model of the unfavorable beam segment. Based on the extended finite element theory, it performs bridge cracking analysis on the local model. It utilizes the characteristics of the extended finite element theory, which allows for discontinuities in elements and simulates the initiation and propagation of cracks in various directions without the need for re-meshing, to quickly obtain the cracking situation of the beam segment in the model, reducing the amount of calculation and shortening the research cycle. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the finite element model of the entire bridge in an embodiment of the present invention;

[0040] Figure 2 The diagrams shown are the first principal stress diagrams of the main beam under gradient heating in this embodiment of the invention, wherein (a) is the first principal stress diagram of the bottom plate of the main beam under gradient heating, (b) is the first principal stress diagram of the web plate of the main beam under gradient heating, and (c) is the first principal stress diagram of the top plate of the main beam under gradient heating.

[0041] Figure 3 The diagrams shown are the first principal stress diagrams of the main beam under gradient cooling in this embodiment of the invention, where (d) is the first principal stress diagram of the bottom plate of the main beam under gradient cooling, (e) is the first principal stress diagram of the web plate of the main beam under gradient cooling, and (f) is the first principal stress diagram of the top plate of the main beam under gradient cooling.

[0042] Figure 4 This invention relates to the changes in the first principal stress at three different locations of the main beam—the top plate, the bottom plate, and the web plate—under different degrees of overall temperature action in this embodiment of the invention. Here, (g) represents the maximum change in the first principal stress under different overall cooling effects, and (h) represents the maximum change in the first principal stress under different overall heating effects.

[0043] Figure 5 The first principal stress diagram of the main beam when the coefficient combination is five in the embodiment of the present invention is shown, wherein (l) is the first principal stress diagram of the bottom plate of the main beam when the coefficient combination is five, (m) is the first principal stress diagram of the web plate of the main beam when the coefficient combination is five, and (n) is the first principal stress diagram of the top plate of the main beam when the coefficient combination is five.

[0044] Figure 6 This is a schematic diagram of the first principal stress of the top plate of the upper chord S4 beam segment and the bottom plate of the mid-span closure segment under different coefficient combinations in an embodiment of the present invention, wherein (p) is the first principal stress diagram of the upper chord S4 beam segment under different coefficient combinations, and (q) is the first principal stress diagram of the bottom plate of the mid-span closure segment under different coefficient combinations.

[0045] Figure 7 These are the first principal stress diagrams of the S4 beam segment and the span closure segment under different operating years in the embodiments of the present invention, where (r) is the first principal stress diagram of the upper chord S4 beam segment under different operating years, and (s) is the first principal stress diagram of the bottom plate of the mid-span closure segment under different operating years.

[0046] Figure 8 This is a partial model of the upper chord S4 beam segment in an embodiment of the present invention;

[0047] Figure 9 This is a partial model of beam segment 33 at mid-span in an embodiment of the present invention;

[0048] Figure 10This is the first principal stress diagram of the bottom plate of beam segment 33 in the mid-span of this embodiment of the invention. Detailed Implementation

[0049] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0050] This invention proposes a method for analyzing bridge cracking based on extended finite element theory, the method comprising:

[0051] S1. Create a finite element model of the entire bridge.

[0052] Specifically, this embodiment of the invention relies on the original design of the Yunnan Zhuang Grand Bridge, an engineering example. A finite element model of the entire bridge is created in MIDAS software, and the load combination under the normal serviceability limit state of the bridge is determined according to the "Design Specification for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" JTG3362-2018. The finite element model of the bridge is as follows: Figure 1 As shown.

[0053] S2. Considering the stress conditions of the bridge structure under different temperature changes, different coefficient combinations, and different service years, determine the most unfavorable beam segment.

[0054] Step S2 specifically includes the following sub-steps:

[0055] S21. In the original design of the bridge, the changes in the first principal stress of the top plate, web and bottom plate of the main beam under different temperature changes should be considered.

[0056] This invention considers the changes in the first principal stress at three different locations—the top plate, bottom plate, and web plate of the main beam—under gradient heating, gradient cooling, and different degrees of overall temperature change, respectively, to determine the influence of different degrees of overall temperature on the cracking trend of the bridge.

[0057] like Figure 2 The diagrams shown depict the first principal stresses of the main beam under gradient heating, where (a) represents the first principal stress of the bottom plate of the main beam under gradient heating, (b) represents the first principal stress of the web of the main beam under gradient heating, and (c) represents the first principal stress of the top plate of the main beam under gradient heating. Figure 2 It is known that the first principal stress generated in the bottom plate of the main beam under the gradient heating effect is relatively large, which may lead to cracking of the bottom plate of the main beam.

[0058] Figure 3The diagram shows the first principal stress diagram of the main beam under gradient cooling, where (d) is the first principal stress diagram of the bottom plate of the main beam under gradient cooling, (e) is the first principal stress diagram of the web plate of the main beam under gradient cooling, and (f) is the first principal stress diagram of the top plate of the main beam under gradient cooling. Analysis Figure 3 It can be seen that the gradient cooling effect has a significant impact on the first principal stress of the main beam top plate, resulting in a more obvious cracking tendency of the main beam. Therefore, the gradient temperature effect has a significant impact on the stress of the bridge structure, and its impact on the cracking of the bridge structure also needs to be taken seriously.

[0059] like Figure 4 The figure shows the changes in the first principal stress at three different locations on the top plate, bottom plate, and web of the main beam under different degrees of overall temperature action. Among them, (g) represents the maximum change in the first principal stress under different overall cooling effects, and (h) represents the maximum change in the first principal stress under different overall heating effects.

[0060] Depend on Figure 4 It can be seen that as the overall temperature rises and falls, the changes in the primary principal stress at the top, bottom, and web plates of the main girder basically follow the same pattern. For every 2°C decrease in the absolute value of the overall temperature drop, the maximum primary principal stress at each location of the main girder increases by approximately 0.02 MPa; for every 2°C increase in the overall temperature rise, the maximum primary principal stress at the top and web plates of the main girder increases by approximately 0.02 MPa, and specifically, the maximum primary principal stress at the bottom plate increases by about 0.08 MPa. Analysis of the changes in the primary principal stress at the top, web, and bottom plates of the main girder under different overall temperature values ​​shows that the overall temperature setting may lead to larger primary principal stresses in the bridge structure, thus creating a tendency for cracking.

[0061] S22. Analyze the stress conditions of the bridge structure under different combinations of pipe wall friction coefficient μ and pipe deviation coefficient k.

[0062] A review of numerous domestic literature and reports on the measurement and calculation of prestressed tendon duct friction loss reveals that domestic considerations for prestressed tendon friction loss are relatively conservative. Therefore, this invention determines the optimal combination of the pipe wall friction coefficient μ and the influence coefficient k of pipe deviation on friction under different combinations of coefficients to assess the stress conditions of bridge structures and to identify areas with a tendency to crack.

[0063] Based on this, this paper explores the stress conditions of bridge structures under the following different combinations of pipe wall friction coefficient μ and pipe deviation coefficient k, namely:

[0064] In this embodiment, the values ​​of the pipe wall friction coefficient μ and the influence coefficient k of pipe deviation on friction both show an increasing trend in the different coefficient combinations. The five coefficient combinations are as follows:

[0065] (1) Coefficient combination one: μ = 0.25, k = 0.0015

[0066] (2) Coefficient combination two: μ = 0.35, k = 0.0040

[0067] (3) Coefficient combination three: μ = 0.50, k = 0.0070

[0068] (4) Coefficient combination four: μ = 0.80, k = 0.0085

[0069] (5) Coefficient combination five: μ = 0.90, k = 0.0095

[0070] The first principal stress diagrams of the main beam were tested under five different coefficient combinations, and the magnitudes of the first principal stresses were compared to obtain the coefficient combinations corresponding to the first principal stresses. The comparison shows that when μ and k are both in coefficient combination five, the first principal stress is relatively large. Figure 5 The diagram shows the first principal stress diagram of the main beam when the coefficient combination is five. Among them, (l) is the first principal stress diagram of the bottom plate of the main beam when the coefficient combination is five, (m) is the first principal stress diagram of the web plate of the main beam when the coefficient combination is five, and (n) is the first principal stress diagram of the top plate of the main beam when the coefficient combination is five. The two piers in (l), (m), and (n) are pier No. 13 and pier No. 14, respectively.

[0071] analyze Figure 5 It can be seen that when μ and k are taken as coefficient combination five, the first principal stress generated by the bottom plate of the closure section in (l) is relatively large, reaching 2.27 MPa, which is close to the tensile strength of C55 concrete of 2.74 MPa, and there is a tendency to crack; while the first principal stress generated by the web of the main beam in (m) is relatively small, with a maximum value of only 1.05 MPa, and there is no obvious tendency to crack; but the first principal stress generated by the top plate of the main beam in (n) is very large. The top plates of the S1-S5 beam segment and the S1'-S5' beam segment near piers 13 and 14 all have a first principal stress greater than 3.0 MPa. The most unfavorable beam segment is the S4 beam segment near pier 14, with a first principal stress of about 4.37 MPa at the top, which is much greater than the standard value of the axial tensile strength of C55 grade concrete of 2.74 MPa, and has a very obvious tendency to crack.

[0072] Considering the different values ​​of the pipe wall friction coefficient μ and the influence coefficient k of pipe deviation on friction, the prestress loss of the structure is relatively large, and the first principal stress generated at different locations of the structure is relatively large, especially at the top plate of the upper chord S4 beam segment and the bottom plate of the mid-span closure segment, where there is a significant tendency for cracking. Further analysis of the first principal stress of the top plate of the upper chord S4 beam segment and the bottom plate of the mid-span closure segment yields the following results: Figure 6The diagram shows the first principal stress of the top slab of the upper chord S4 beam segment and the bottom slab of the mid-span closure segment under different coefficient combinations. (p) represents the first principal stress of the upper chord S4 beam segment under different coefficient combinations, and (q) represents the first principal stress of the bottom slab of the mid-span closure segment under different coefficient combinations. Figure 6 It can be seen that as the values ​​of μ and k increase, the first principal stress generated by the top plate of the upper chord S4 beam segment and the bottom plate of the mid-span closure segment also increases, thereby increasing the risk of beam cracking.

[0073] S23. Test the stress changes of various parts of the bridge structure under different years of operation.

[0074] The creep effect of concrete is a long-term process. Under prolonged loading, the increased stress on concrete structures can lead to the propagation of cracks and a decrease in deflection, jeopardizing the normal use of the bridge. Current research on this phenomenon is insufficient for many bridges. This example analyzes six operational stages of the bridge: newly completed, 4 years after completion, 8 years after completion, 12 years after completion, 16 years after completion, and 20 years after completion, to obtain the stress conditions of various structural components. Figure 7 The diagram shows the first principal stress diagrams of beam segment S4 and the mid-span closure segment under different service years, where (r) represents the first principal stress diagram of the upper chord S4 beam segment under different service years, and (s) represents the first principal stress diagram of the bottom slab of the mid-span closure segment under different service years. Figure 7 It can be seen that the first principal stress generated by the top plate of the S4 beam segment and the bottom plate of the mid-span closure segment will increase with the extension of the bridge's service life, increasing the tendency of the beam segment to crack, which undoubtedly increases the safety hazards for the normal use of the bridge.

[0075] S24. Calculate the bridge load conditions according to the specifications, obtain the most unfavorable conditions, and analyze the beam segments with cracking tendency under this most unfavorable conditions.

[0076] S25. Determine the most unfavorable beam segment for bridge cracking.

[0077] Steps S21 to S24 above analyzed the effects of temperature changes of different degrees, the different combinations of coefficients of pipe wall friction coefficient μ and pipe deviation on friction coefficient k, the stress changes of various parts of the bridge structure under different operating years, and the most unfavorable working conditions. Based on the above analysis results, the beam segments with cracking tendency can be identified, and the beam segments with cracking tendency are identified as the most unfavorable beam segments.

[0078] Based on the above analysis, the top slab of the upper chord S4 beam segment and the bottom slab of the mid-span 33 beam segment of the Yunnan Zhuang Grand Bridge have a very obvious cracking trend. Therefore, the most unfavorable beam segments of the Yunnan Zhuang Grand Bridge are the upper chord S4 beam segment and the mid-span 33 beam segment.

[0079] S3. Expand the scope of the most unfavorable beam segment and establish a local model of the most unfavorable beam segment of the bridge.

[0080] The stress boundary of the entire bridge is extracted based on Saint-Venant's principle, and the unfavorable region near the most unfavorable beam segment is determined based on the stress magnitude.

[0081] The unfavorable beam segment is determined by expanding its range based on the unfavorable region near it. A geometric model of this unfavorable segment is then created in Revit software. For the Yunnan Zhuang Grand Bridge, the most unfavorable beam segments are the upper chord S4 segment and the mid-span segment 33. Therefore, the geometric model is established covering upper chord segments S2 to S6 and mid-span segments 31 to 33. The geometric model of the unfavorable beam segment is then imported into Hypermesh software. Considering the large size of the model, and to balance calculation accuracy and efficiency, most of it is divided into hexahedral elements. This achieves the conversion from the bridge's geometric model to a solid model, resulting in the solid model of the unfavorable beam segment.

[0082] The solid model of the unfavorable beam segment is then imported into the ABAQUS finite element software as a component to obtain the local models of the upper chord S4 beam segment and the mid-span 33 beam segment, i.e., the local models of the unfavorable beam segment, as shown below. Figure 8 and Figure 9 The figures shown are local models of the upper chord S4 beam segment and the mid-span 33 beam segment, respectively.

[0083] The stress boundary conditions acting on the upper chord S4 beam segment and the mid-span 33 beam segment were extracted from the overall bridge model. To verify the correctness of the local model, the stress results of the local model were compared with the calculation results of the full-bridge MIDAS model. Figure 10 The diagram shown is the first principal stress diagram of the bottom slab of beam segment 33 at mid-span. Figure 10 It can be seen that the maximum value of the first principal stress at the bottom plate of the mid-span beam segment in the local model is 3.29 MPa, which is not much different from 2.82 MPa in the MIDAS software. The error is within an acceptable range, indicating that the established local model can accurately and effectively simulate the local area.

[0084] S5. Based on the extended finite element theory, cracking analysis was performed on the local model of the most unfavorable beam segment to calculate the local stress of the bridge and analyze the crack generation and propagation.

[0085] Based on the extended finite element method, precast cracks were embedded at appropriate locations in the local model of beam segment 33 at mid-span and beam segment S4 on the upper chord. The maximum principal stress traction cracking criterion for C55 concrete was set, and the fracture energy of C55 concrete was input into the model. This completed the relevant settings of the extended finite element method in the local model.

[0086] The stress boundary of the most unfavorable beam segment under the most unfavorable working condition is extracted. This extracted stress boundary is then applied to a local model of the unfavorable beam segment, while simultaneously considering the load on the local beam segment itself. The stress conditions of the local beam segment under the most unfavorable working condition are simulated and analyzed to perform bridge cracking simulation analysis. From the analysis results, PHILSM contour plots of the upper chord S4 beam segment and the mid-span 33 beam segment at different stages are retrieved to observe the cracking situation of the beam segments, thereby analyzing the crack initiation and propagation.

[0087] Corresponding to the above-described method embodiments, this invention also proposes a bridge cracking analysis system based on extended finite element theory, the system comprising:

[0088] Full Bridge Model Creation Module: Used to create a finite element model of the entire bridge.

[0089] The module for determining the most unfavorable beam segment is used to consider the stress conditions of bridge structures under different temperature changes, different combinations of coefficients, and different service years, and to determine the most unfavorable working conditions; and to determine the most unfavorable beam segment under the most unfavorable working conditions.

[0090] Local model building module: used to expand the scope of the most unfavorable beam segment and build a local model of the most unfavorable beam segment of the bridge;

[0091] Beam segment cracking analysis module: Based on the extended finite element theory, cracking analysis is performed on the local model of the most unfavorable beam segment, and the local stress of the bridge and the initiation and propagation of cracks are calculated.

[0092] The above system embodiments and method embodiments are one-to-one correspondences. For a brief description of the system embodiments, please refer to the method embodiments.

[0093] The present invention also discloses an electronic device, comprising: at least one processor, at least one memory, a communication interface, and a bus; wherein the processor, memory, and communication interface communicate with each other through the bus; the memory stores program instructions executable by the processor, and the processor calls the program instructions to implement the aforementioned method of the present invention.

[0094] The present invention also discloses a computer-readable storage medium that stores computer instructions, which cause the computer to implement all or part of the steps of the method described in the embodiments of the present invention. The storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0095] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, meaning they can be distributed across multiple network units. Those skilled in the art can select some or all of the modules to achieve the purpose of this embodiment without any inventive effort, based on actual needs.

[0096] 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 within the protection scope of the present invention.

Claims

1. A method for analyzing bridge cracking based on extended finite element theory, characterized in that, The method includes: Create a finite element model of the entire bridge; Considering the stress conditions of the bridge structure under different temperature changes, different coefficient combinations, and different service years, the most unfavorable beam segment is determined. Expand the scope of the most unfavorable beam segment and establish a local model of the most unfavorable beam segment of the bridge; Based on the extended finite element method, a cracking analysis was performed on the local model of the most unfavorable beam segment. The local stress of the bridge was calculated, and the crack generation and propagation were analyzed. The stress conditions of bridge structures under different temperature changes, different combinations of coefficients, and different service years specifically include: Considering the changes in the first principal stress at three different locations—the top plate, bottom plate, and web plate—of the main beam under different temperature changes, the influence of different degrees of temperature on the cracking trend of the bridge is determined. Test pipe wall friction coefficient μ The influence coefficient of pipe deviation on friction k The stress conditions of the bridge structure under different coefficient combinations were investigated, and the tube wall friction coefficient under conditions with a tendency to crack was determined. μ The influence coefficient of pipe deviation on friction k The optimal combination of coefficients; Test the stress changes of various structural components of the bridge under different years of operation; Based on the influence of different degrees of overall temperature on the cracking trend of bridges, and the coefficient of pipe wall friction μ The influence coefficient of pipe deviation on friction k By analyzing the optimal combination of coefficients and the stress changes of various structural parts of the bridge under different operating years, beam segments with a tendency to crack were identified, and these segments were designated as the most unfavorable beam segments.

2. The bridge cracking analysis method based on extended finite element theory according to claim 1, wherein considering the changes in the first principal stress at three different locations—the top plate, bottom plate, and web plate of the main beam—under different temperature changes, and determining the influence of different degrees of temperature on the bridge cracking trend specifically includes: The effects of gradient heating, gradient cooling, and different degrees of overall temperature change on the cracking trend of the bridge are determined by considering the changes in the first principal stress at three different locations of the main beam: the top plate, the bottom plate, and the web plate.

3. The bridge cracking analysis method based on extended finite element theory according to claim 2, wherein in the different coefficient combinations, the pipe wall friction coefficient... μ The influence coefficient of pipeline deviation on friction k The values ​​all show an increasing trend.

4. The bridge cracking analysis method based on extended finite element theory according to claim 1, wherein expanding the range of the most unfavorable beam segment and establishing a local model of the most unfavorable beam segment of the bridge specifically includes: Identify the unfavorable region near the most unfavorable beam segment; Expand the range of the most unfavorable beam segment based on the unfavorable region near the most unfavorable beam segment to obtain the unfavorable beam segment, and build the geometric model of the unfavorable beam segment in Revit software; The geometric model of the unfavorable beam segment is imported into Hypermesh software, a finite element mesh is generated, and the solid model of the unfavorable beam segment is obtained. The solid model of the unfavorable beam segment is imported into the ABAQUS finite element calculation software as a component to obtain the local model of the unfavorable beam segment.

5. The bridge cracking analysis method based on extended finite element theory according to claim 4, wherein the cracking analysis of the local model of the most unfavorable beam segment based on extended finite element theory, the calculation of the local stress of the bridge, and the analysis of crack generation and propagation specifically include: Based on the extended finite element theory, precast cracks are embedded at appropriate locations in the local model of the unfavorable beam segment. The maximum principal stress traction cracking criterion for C55 concrete is set, and the fracture energy of C55 concrete is input into the model. Extract the stress boundary of the most unfavorable beam segment under the most unfavorable working condition, apply the extracted stress boundary to the local model of the unfavorable beam segment, and at the same time consider the load on the local beam segment itself to simulate and analyze the stress situation of the local beam segment under the most unfavorable working condition. PHILSM contour plots of the unfavorable beam segment at different stages were obtained to observe the cracking situation of the beam segment.

6. The bridge cracking analysis method based on extended finite element theory according to claim 3, wherein the bridge is the Yunnan Zhuang Grand Bridge, and the most unfavorable beam segments are the upper chord S4 beam segment and the mid-span No. 33 beam segment.

7. A bridge crack analysis system based on extended finite element theory, used to implement the bridge crack analysis method based on extended finite element theory as described in any one of claims 1 to 6, characterized in that, The system includes: Full Bridge Model Creation Module: Used to create a finite element model of the entire bridge. The module for determining the most unfavorable beam segment is used to consider the stress conditions of bridge structures under different temperature changes, different combinations of coefficients, and different service years, and to determine the most unfavorable working conditions; and to determine the most unfavorable beam segment under the most unfavorable working conditions. Local model building module: used to expand the scope of the most unfavorable beam segment and build a local model of the most unfavorable beam segment of the bridge; Beam segment cracking analysis module: Based on the extended finite element theory, cracking analysis is performed on the local model of the most unfavorable beam segment, and the local stress of the bridge and the initiation and propagation of cracks are calculated.

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