Numerical simulation method of coupling effect of concrete multi-axial stress state and freeze-thaw cycles

Abstract

The present disclosure relates to the field of concrete mechanics, and particularly relates to a numerical simulation method for the coupling effect of the multi-axial stress state and freeze-thaw cycles of concrete. The numerical simulation method comprises: creating a simplified meso-concrete finite element model by using dimension reduction technology and meso-component reduction technology; setting parameters for the simplified meso-concrete finite element model according to coupling effect parameters (including freeze-thaw cycle parameters and multi-axial stress state parameters); and performing a finite element analysis of the coupling effect of concrete (including damage analysis of the coupling effect of concrete and analysis of the mechanical properties of concrete after damage of the coupling effect of concrete) on the simplified meso-concrete finite element model after parameter setting. This process realizes numerical simulation of the coupling effect of the multi-axial stress state and freeze-thaw cycles of concrete in a simple and efficient manner, makes the freeze-thaw cycle analysis of concrete more in line with actual stress conditions, improves the calculation accuracy and efficiency, and is suitable for engineering applications.

Description

Technical Field

[0001] This disclosure relates to the field of concrete mechanics, and in particular to a numerical simulation method for the multiaxial stress state of concrete and the coupling effect of freeze-thaw cycles. Background Technology

[0002] Throughout its service life in cold regions such as polar regions, oceans, and plateaus, concrete is subjected to a complex multiaxial stress state coupled with freeze-thaw cycles. As temperatures decrease, the pore water inside the concrete gradually freezes and expands, generating pore pressure that couples with the multiaxial stress state. Compared to stress-free coupling, the coupling of pore pressure and multiaxial stress leads to more complex freeze-thaw damage. Currently, most research on the freeze-thaw resistance of concrete does not consider the impact of this coupling, resulting in discrepancies with reality. The limited research addressing this coupling relies heavily on experimental methods, which are costly and time-consuming. There is an urgent need for an efficient research method that addresses the coupling effect of multiaxial stress state and freeze-thaw cycles in concrete to ensure its safe application in cold regions and promote development and construction in extreme environments such as polar regions, oceans, and plateaus. Summary of the Invention

[0003] In view of this, this disclosure proposes a numerical simulation technique for the coupling effect of multiaxial stress state and freeze-thaw cycle in concrete.

[0004] According to one aspect of this disclosure, a numerical simulation method for the multiaxial stress state and freeze-thaw cycle coupling effect of concrete is provided, comprising:

[0005] A simplified micro-concrete finite element model was created using dimensional simplification and meso-component simplification techniques.

[0006] Based on the coupling effect parameters, the parameters of the simplified micro-concrete finite element model are set, including freeze-thaw cycle parameters and multiaxial stress state parameters.

[0007] A finite element analysis of concrete coupling effect is performed on the simplified micro-concrete finite element model after parameter setting. The finite element analysis of concrete coupling effect includes damage analysis of concrete coupling effect and mechanical property analysis of concrete after damage due to concrete coupling effect.

[0008] In one possible implementation, the creation of a simplified mesoscopic concrete finite element model using dimensional simplification and mesoscopic component simplification techniques includes:

[0009] When the three-dimensional concrete model is cylindrical, the column symmetry technique is used to obtain a two-dimensional finite element model section that can reflect the three-dimensional performance.

[0010] Based on the cross section of the two-dimensional finite element model, an axisymmetric technique is used to obtain a two-dimensional symmetrical finite element model that can reflect three-dimensional performance.

[0011] In one possible implementation, the creation of a simplified mesoscopic concrete finite element model using dimensional simplification and mesoscopic component simplification techniques includes:

[0012] On the cross section of the two-dimensional finite element model, only concrete elements and pore elements randomly distributed on the concrete elements are set.

[0013] The pore unit and the concrete unit are constrained by an embedded method.

[0014] In one possible implementation, the freeze-thaw cycle parameters include freeze-thaw cycle temperature and number of freeze-thaw cycles; the parameter setting of the simplified mesoscopic concrete finite element model based on coupling effect parameters includes:

[0015] The temperature variation range of the pore unit and the concrete unit is determined based on the freeze-thaw cycle temperature.

[0016] The linear expansion coefficient of the pore unit is set according to the temperature change range and the number of freeze-thaw cycles;

[0017] The elastic modulus of the pore unit is set according to the temperature change range.

[0018] In one possible implementation, setting the parameters of the simplified mesoscopic concrete finite element model based on coupling effect parameters includes:

[0019] Based on the external multiaxial loads or multiaxial constraints applied to the three-dimensional concrete model, loads or constraints are set for the simplified mesoscopic concrete finite element model.

[0020] The coefficient of restitution for compressive stiffness of concrete is defined as 0.6.

[0021] In one possible implementation, the concrete coupling effect damage analysis includes:

[0022] The degree and location distribution of compressive damage in concrete under multiaxial stress state and freeze-thaw cycle coupling effect;

[0023] The degree and location distribution of tensile damage under multiaxial stress state and freeze-thaw cycle coupling effect in concrete.

[0024] In one possible implementation, the mechanical property analysis of the concrete after coupling effect damage includes:

[0025] By applying uniaxial or multiaxial loads to the finite element model of concrete under multiaxial stress state and damage caused by freeze-thaw cycle coupling effect, the uniaxial or multiaxial mechanical properties of concrete after damage caused by coupling effect are obtained.

[0026] Based on the uniaxial or multiaxial mechanical properties of the concrete, a calculation model for the multiaxial stress state and freeze-thaw cycle coupling effect is obtained.

[0027] According to another aspect of this disclosure, a numerical simulation apparatus for the multiaxial stress state of concrete and the coupling effect of freeze-thaw cycles is provided, comprising:

[0028] The model creation module is used to create simplified micro-concrete finite element models using dimensional simplification and meso-component simplification techniques.

[0029] The parameter setting module is used to set parameters for the simplified micro-concrete finite element model based on the coupling effect parameters, which include freeze-thaw cycle parameters and multiaxial stress state parameters.

[0030] The finite element analysis module is used to perform finite element analysis of concrete coupling effects on the simplified micro-concrete finite element model after parameter setting. The finite element analysis of concrete coupling effects includes damage analysis of concrete coupling effects and mechanical property analysis of concrete after damage due to concrete coupling effects.

[0031] In one possible implementation, the model creation module is used for:

[0032] When the three-dimensional concrete model is cylindrical, the column symmetry technique is used to obtain a two-dimensional finite element model section that can reflect the three-dimensional performance.

[0033] Based on the cross section of the two-dimensional finite element model, an axisymmetric technique is used to obtain a two-dimensional symmetrical finite element model that can reflect three-dimensional performance.

[0034] In one possible implementation, the model creation module is used for:

[0035] On the cross section of the two-dimensional finite element model, only concrete elements and pore elements randomly distributed on the concrete elements are set.

[0036] The pore unit and the concrete unit are constrained by an embedded method.

[0037] In one possible implementation, the freeze-thaw cycle parameters include the freeze-thaw cycle temperature and the number of freeze-thaw cycles; the parameter setting module is used for:

[0038] The temperature variation range of the pore unit and the concrete unit is determined based on the freeze-thaw cycle temperature.

[0039] The linear expansion coefficient of the pore unit is set according to the temperature change range and the number of freeze-thaw cycles;

[0040] The elastic modulus of the pore unit is set according to the temperature change range.

[0041] In one possible implementation, the parameter setting module is used for:

[0042] Based on the external multiaxial loads or multiaxial constraints applied to the three-dimensional concrete model, loads or constraints are set for the simplified mesoscopic concrete finite element model.

[0043] The coefficient of restitution for compressive stiffness of concrete is defined as 0.6.

[0044] In one possible implementation, the concrete coupling effect damage analysis includes:

[0045] The degree and location distribution of compressive damage in concrete under multiaxial stress state and freeze-thaw cycle coupling effect;

[0046] The degree and location distribution of tensile damage under multiaxial stress state and freeze-thaw cycle coupling effect in concrete.

[0047] In one possible implementation, the mechanical property analysis of the concrete after coupling effect damage includes:

[0048] By applying uniaxial or multiaxial loads to the finite element model of concrete under multiaxial stress state and damage caused by freeze-thaw cycle coupling effect, the uniaxial or multiaxial mechanical properties of concrete after damage caused by coupling effect are obtained.

[0049] Based on the uniaxial or multiaxial mechanical properties of the concrete, a calculation model for the multiaxial stress state and freeze-thaw cycle coupling effect is obtained.

[0050] According to another aspect of this disclosure, an electronic device is provided, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to implement the above-described method when executing instructions stored in the memory.

[0051] According to another aspect of this disclosure, a non-volatile computer-readable storage medium is provided that stores computer program instructions thereon, wherein the computer program instructions, when executed by a processor, implement the above-described method.

[0052] According to another aspect of this disclosure, a computer program product is provided, including computer-readable code, or a non-volatile computer-readable storage medium carrying computer-readable code, wherein when the computer-readable code is run in a processor of an electronic device, the processor in the electronic device performs the above-described method.

[0053] In this embodiment, a simplified micro-concrete finite element model was created, its parameters were set, and finally, a finite element analysis of concrete coupling effects was performed on the simplified micro-concrete finite element model. During model creation, dimensional simplification and micro-component simplification techniques were combined. While maintaining the three-dimensional coupling effect analysis function, the model's dimensional and component complexity was reduced, significantly lowering the difficulty of creating the micro-concrete finite element model and greatly improving the computational efficiency of numerical simulation while ensuring computational accuracy. The embedded constraints of pore elements and concrete elements avoid the repeated trial calculations and corrections of concrete material constitutive parameters required by traditional constraint replacement. Conventional material constitutive parameters can be directly applied, making them easier to determine and more reliable, and more suitable for engineering applications. During parameter setting, the established model was parameterized according to the coupling effect parameters to further realize the numerical simulation of the multiaxial stress state and freeze-thaw cycle coupling effect of concrete, making the concrete freeze-thaw cycle analysis more consistent with actual stress conditions and improving computational accuracy.

[0054] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure.

[0055] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0056] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this disclosure together with the specification and serve to explain the principles of this disclosure.

[0057] Figure 1 A flowchart is shown illustrating a numerical simulation method for the multiaxial stress state of concrete and the coupling effect of freeze-thaw cycles according to an embodiment of the present disclosure.

[0058] Figure 2 A schematic diagram is shown of a two-dimensional finite element model obtained by means of a symmetry technique according to an embodiment of the present disclosure.

[0059] Figure 3 A schematic diagram showing a reasonably simplified two-dimensional finite element model according to an embodiment of the present disclosure is shown.

[0060] Figure 4 The diagram shows the variation of relative compressive strength of a finite element model according to an embodiment of the present disclosure.

[0061] Figure 5 A schematic diagram showing the formula verification result according to an embodiment of the present disclosure is provided.

[0062] Figure 6A flowchart is shown illustrating a numerical simulation method for multiaxial stress state and freeze-thaw cycle coupling effect of concrete-filled steel tubular material according to an application example of this disclosure.

[0063] Figure 7 A finite element model of a concrete-filled steel tube member is shown as an application example according to this disclosure.

[0064] Figure 8 The diagram shows a damage distribution cloud obtained by analyzing a finite element model according to an application example of this disclosure.

[0065] Figure 9 A diagram showing test data verification of a concrete / concrete-steel tubular member according to an application example of this disclosure is displayed.

[0066] Figure 10 A block diagram of a numerical simulation apparatus for the multiaxial stress state of concrete and the coupling effect of freeze-thaw cycles according to an embodiment of the present disclosure is shown.

[0067] Figure 11 A block diagram of an electronic device according to an embodiment of the present disclosure is shown.

[0068] Figure 12 A block diagram of an electronic device according to an embodiment of the present disclosure is shown. Detailed Implementation

[0069] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0070] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0071] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0072] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0073] Concrete is the most widely used building material in my country's infrastructure construction, commonly applied to various structural forms such as reinforced concrete structures, steel-concrete composite structures, and steel-concrete composite structures. Concrete is a heterogeneous composite material composed of aggregates, interface transition zones, pores, and hardened cement paste. Aggregates refer to the granular materials that act as a skeleton or filler in concrete. Generally, concrete aggregates are classified according to particle size into coarse aggregates (greater than 4.75mm) and fine aggregates (less than 4.75mm). Coarse aggregates generally refer to pebbles and crushed stone, while fine aggregates generally refer to natural sand and manufactured sand.

[0074] Concrete is mostly exposed to the outdoors, and adverse factors such as wind, sun, environmental pollution, and weather changes can reduce its durability. Concrete used in cold regions such as polar regions, oceans, and high plateaus is particularly susceptible to freeze-thaw cycle damage, affecting the service life of concrete structures. Research on concrete freeze-thaw cycles has significant economic and social implications.

[0075] Concrete is subjected to complex multiaxial stress states for extended periods during its service life. As temperatures decrease, the pore water within the concrete gradually freezes and expands, generating pore pressure that couples with the multiaxial stress state. Compared to stress-free coupling, the coupling of pore pressure and multiaxial stress leads to more complex freeze-thaw damage in concrete. Currently, most research on the freeze-thaw resistance of concrete does not consider the impact of this coupling, resulting in discrepancies with reality. The limited research addressing this coupling primarily employs experimental methods, which are costly and time-consuming. Existing numerical simulation methods only address stress-free freeze-thaw cycles and utilize complex three-dimensional microscopic models, while traditional two-dimensional models cannot reflect the coupling effect between triaxial stress states and freeze-thaw cycles. There is an urgent need for an efficient research method that can address the coupling effect between the multiaxial stress state and freeze-thaw cycles in concrete to ensure the safe application of concrete in cold regions and promote the development and construction of extreme environments such as polar regions, oceans, and plateaus.

[0076] Figure 1The flowchart shows a numerical simulation method for the coupled effect of multi - axial stress state and freeze - thaw cycles of concrete according to an embodiment of the present disclosure. This method can be applied to a numerical simulation device for the coupled effect of multi - axial stress state and freeze - thaw cycles of concrete. The numerical simulation device for the coupled effect of multi - axial stress state and freeze - thaw cycles of concrete can be a terminal device, a server, or other processing devices, etc. Among them, the terminal device can be a user equipment (UE), a mobile device, a user terminal, a terminal, a cellular phone, a cordless phone, a personal digital assistant (PDA), a handheld device, a computing device, a vehicle - mounted device, a wearable device, etc.

[0077] In some possible implementation manners, the numerical simulation method for the coupled effect of multi - axial stress state and freeze - thaw cycles of concrete can be implemented by a processor calling computer - readable instructions stored in a memory.

[0078] As Figure 1 shown, the numerical simulation method for the coupled effect of multi - axial stress state and freeze - thaw cycles of concrete can include:

[0079] Step S11, creating a simplified meso - scale concrete finite - element model by using a dimensionality reduction technique and a meso - scale component reduction technique.

[0080] Among them, the dimensionality reduction technique is a technique that uses a finite - element model with reduced dimensions but capable of reflecting the characteristics of the original dimensions to analyze the characteristics of the original - dimension model. Specifically, a finite - element model with M dimensions but capable of reflecting the characteristics of N dimensions can be used to analyze the characteristics of the N - dimension model (M and N are positive integers, M < N). For the present disclosure, a two - dimensional concrete finite - element model with three - dimensional characteristics can be used to analyze the characteristics of a three - dimensional concrete model. Currently, for the analysis of the coupled effect of multi - axial stress state and freeze - thaw cycles of concrete, experimental research methods are mostly used, which are costly, time - consuming, and laborious, and it is difficult to explain the dynamic process of concrete freeze - thaw damage development from a microscopic perspective. A small number of existing numerical simulation methods use relatively complex three - dimensional meso - scale models, and the existing models only target freeze - thaw cycles without stress - state coupling, and do not involve the coupled effect of multi - axial stress state and freeze - thaw cycles; while traditional two - dimensional models cannot reflect the coupled effect of multi - axial stress state and freeze - thaw cycles. The present disclosure uses a dimensionality reduction technique to establish a concrete finite - element model, which can effectively reduce the complexity of the concrete finite - element model.

[0081] In one example, the creating a simplified meso - scale concrete finite - element model by using a dimensionality reduction technique and a meso - scale component reduction technique includes:

[0082] When the three-dimensional concrete model is cylindrical, the column symmetry technique is used to obtain a two-dimensional finite element model section that can reflect the three-dimensional performance.

[0083] Based on the cross section of the two-dimensional finite element model, an axisymmetric technique is used to obtain a two-dimensional symmetrical finite element model that can reflect three-dimensional performance.

[0084] The three-dimensional concrete model mentioned herein is an actual existing model used to experimentally verify the numerical simulation results of the finite element model disclosed in this invention. In one example, a real-world cylindrical three-dimensional concrete model can be obtained by superimposing a certain two-dimensional cross-section (i.e., a two-dimensional finite element model cross-section) based on column symmetry. Since the superimposed two-dimensional cross-sections are identical, the analysis of the mechanical properties of the three-dimensional concrete model can be obtained through the analysis of this two-dimensional cross-section. In one example, this superposition method can be stretching or rotating the two-dimensional cross-section. Furthermore, this two-dimensional cross-section can be further reduced using axisymmetry techniques to obtain a two-dimensional cross-section with the smallest area that reflects the three-dimensional properties (i.e., a two-dimensional symmetric finite element model). Due to the axisymmetric relationship, the analysis of the mechanical properties of the two-dimensional finite element model cross-section can also be obtained through the analysis of this two-dimensional symmetric finite element model with the smallest area. Therefore, a two-dimensional finite element model section that reflects the three-dimensional performance can be found in a real-world cylindrical three-dimensional concrete model. By applying axisymmetric techniques to this two-dimensional finite element model section, a two-dimensional symmetrical finite element model that reflects the three-dimensional performance can be established. Furthermore, finite element analysis of the three-dimensional concrete model can be achieved through finite element analysis of this two-dimensional symmetrical finite element model. Specifically, this disclosure does not impose specific limitations on the methods for determining the two-dimensional finite element model section and the two-dimensional symmetrical finite element model; these can be determined according to the specific actual situation. Further, this disclosure does not impose specific limitations on the shape of the three-dimensional concrete model; it can be selected according to the actual situation. Correspondingly, when the shape of the three-dimensional concrete model is other than cylindrical, the methods for obtaining the two-dimensional finite element model section and the two-dimensional symmetrical finite element model can be flexibly determined according to the actual situation.

[0085] Figure 2 This is a schematic diagram illustrating the two-dimensional finite element model obtained through dimensionality reduction techniques. (See diagram below.) Figure 2As shown, by symmetrically rotating a two-dimensional finite element model along its horizontal axis, a two-dimensional finite element model cross-section can be obtained. By performing a cylindrical symmetric rotation on this cross-section, a three-dimensional cylindrical concrete model can be obtained. During these axisymmetric and cylindrical symmetric operations, the multiaxial loads and stresses of the three-dimensional cylindrical concrete model can be transformed into axial, radial, and circumferential loads and stresses applied to the two-dimensional cross-section. Therefore, finite element analysis of the two-dimensional symmetrical finite element model obtained through the cross-section of the two-dimensional finite element model can reflect the performance of the three-dimensional concrete model.

[0086] This disclosure describes a two-dimensional finite element model obtained from a cylindrical three-dimensional concrete model using columnar symmetry techniques, and an axisymmetric finite element model that reflects the three-dimensional properties. This process achieves the establishment of a two-dimensional symmetric finite element model that maintains the ability to analyze coupling effects in three-dimensional concrete while reducing the complexity of finite element analysis. The modeling method is simple, reduces modeling difficulty, and improves the computational efficiency for subsequent coupling effect analysis.

[0087] Microstructural simplification techniques involve retaining only the components that determine the properties of the model being analyzed, while ignoring components that have little or no effect on these properties. Current research has found that the main factor in the freeze-thaw damage mechanism of concrete is the freezing expansion of pore water. In concrete, complex microstructural components such as coarse and fine aggregates have a relatively small impact on freeze-thaw damage, and their role in the aforementioned coupling effect can be ignored. However, in concrete structures, internal pores have a significant impact on the freeze-thaw resistance of concrete.

[0088] Traditional mesoscopic models of concrete members typically consist of various materials such as mortar, aggregates (coarse aggregates and sand), and interface transition zones (including the transition zone between mortar and aggregates). This results in complex finite element models of concrete members, poor computational convergence, and long computation times, further increasing the computational complexity of obtaining numerical simulation results of concrete members under freeze-thaw cycles using finite element models. In the process of establishing a mesoscopic concrete finite element model, only the pore elements that determine the aforementioned coupling effects and the concrete elements representing the concrete bulk can be retained. In one example, the dimensional simplification technique and the mesoscopic component simplification technique are used to create a simplified mesoscopic concrete finite element model, including:

[0089] On the cross section of the two-dimensional finite element model, only concrete elements and pore elements randomly distributed on the concrete elements are set.

[0090] The pore unit and the concrete unit are constrained by an embedded method.

[0091] Specifically, based on the freeze-thaw cycle damage mechanism, the traditional microscopic model of concrete can be reasonably simplified to establish a finite element model of concrete components with only pore elements and concrete elements. The finite element model can then be analyzed using finite element calculation software to obtain simulated values ​​of concrete under freeze-thaw cycles. Figure 3 This is a schematic diagram illustrating a reasonable simplification of a two-dimensional finite element model. (For example...) Figure 3 As shown, the finite element model before simplification includes random porosity, concrete, coarse aggregate, sand, interface transition zone, and hardened cement paste, while the simplified finite element model only includes random porosity and concrete. In this embodiment, complex modeling of micro-components such as coarse and fine aggregates is unnecessary; only random porosity, the main factor causing durability damage to concrete through freeze-thaw cycles, needs to be introduced to effectively reflect the influence of freeze-thaw cycles on concrete components. In this embodiment, by retaining only finite element elements and concrete elements representing the concrete bulk, the influence of the aforementioned coupling effect on concrete properties is addressed, which helps simplify the concrete finite element model and improve computational efficiency.

[0092] Specifically, the process of setting up pore elements and concrete elements on a two-dimensional symmetric finite element model can include calculating the number of pore elements and calculating the location of pore elements.

[0093] The number of pore elements refers to the number of pore elements in the two-dimensional symmetric finite element model used for finite element analysis. In one example, the overall volume and porosity of the three-dimensional concrete model can be obtained first to get the total volume of pore elements in the three-dimensional concrete model. Then, combined with the volume of individual pores, the number of pore elements in the three-dimensional concrete model can be obtained. Finally, based on the number of pore elements in the three-dimensional concrete model, the number of pore elements in the two-dimensional symmetric finite element model can be obtained. Specifically, the number of pore elements in the three-dimensional concrete model can be calculated using the following formula:

[0094] N = nV c / V p1 Formula (1)

[0095] Where N is the number of pore elements in the concrete member, n is the initial porosity of the concrete (excluding the influence of air-entraining agent), and V c V represents the volume of the concrete component. p1 The volume of a single pore.

[0096] right Figure 2 The two-dimensional symmetric finite element model in the image, after undergoing a rotation operation, only contains the upper half of the three-dimensional concrete model. Therefore... Figure 2 The number of pore elements in the two-dimensional symmetric finite element model should be half the number of pore elements in the three-dimensional concrete model with a cylindrical shape.

[0097] In reality, pores are randomly distributed in concrete; therefore, pore elements in the finite element model should be randomly distributed among concrete elements. In one example, the Monte Carlo method can be used to determine the specific location of each pore element, thereby randomly distributing the pore elements in the three-dimensional finite element model. This disclosure does not impose specific limitations on the method for obtaining the specific location of each pore element when randomly distributing pore elements in a concrete member; the method can be selected according to the actual situation.

[0098] In traditional finite element models of concrete components, pore elements and concrete elements are typically constrained by substitution. When importing the finite element model into finite element calculation software, the material properties of the model need to be set. The material properties of concrete are obtained experimentally. When measuring the material parameters of concrete experimentally, the concrete contains pores, so the measured parameters are for concrete containing pores. If the model uses pores to replace concrete, the pores and concrete will be distinguished in the model, and the concrete elements will become dense materials without pores. The material parameters of this dense material (without pores) will differ from the experimentally obtained material parameters (with pores), requiring complex and iterative calculations for correction; it cannot be used directly.

[0099] In one example, the pore elements and concrete elements are constrained by an embedded method. Compared with the traditional replacement method, it is not necessary to repeatedly calculate and correct the changes in the constitutive parameters of concrete materials caused by the replacement of concrete by pores. Conventional material constitutive parameters can be directly applied, which is easy to determine and more reliable, and more suitable for engineering applications.

[0100] In this embodiment, a micro-component simplification technique is adopted. In a two-dimensional symmetric finite element model, randomly distributed pore elements are embedded and constrained within concrete elements. This achieves the simplest model construction that conforms to the multiaxial stress state and freeze-thaw cycle coupling effect mechanism. It is convenient and efficient in terms of model establishment, parameter selection, and calculation efficiency, and is more suitable for engineering application.

[0101] Step S12: Based on the coupling effect parameters, set the parameters of the simplified micro-concrete finite element model. The coupling effect parameters include freeze-thaw cycle parameters and multiaxial stress state parameters.

[0102] The coupling effect parameters are those that influence the coupling effect between freeze-thaw cycles and multiaxial stress states. To analyze the coupling effect, in one example, the coupling effect parameters may include freeze-thaw cycle parameters and multiaxial stress state parameters. The freeze-thaw cycle parameters influence the effect of freeze-thaw cycles, and the multiaxial stress state parameters influence the effect of multiaxial stress states.

[0103] In practical engineering, concrete materials are generally under multiaxial complex stress states during freeze-thaw cycles. However, traditional studies on concrete freeze-thaw cycles typically do not consider the coupling effect between stress state and freeze-thaw cycle. A few studies have only considered the coupling effect of uniaxial force and freeze-thaw cycle through experiments, without considering the coupling effect of multiaxial force and freeze-thaw cycle. Such research results cannot accurately reflect the mechanical response of concrete under the coupling effect of multiaxial stress state and freeze-thaw cycle. The law of concrete freeze-thaw damage is fundamental to the development and application of concrete structures in cold regions. More realistic studies of concrete freeze-thaw cycle damage can lead to more accurate and rational structural design and analysis, possessing significant engineering, socio-economic, and practical implications. The prerequisite for realistic studies of concrete freeze-thaw cycle damage is considering the coupling effect of multiaxial stress state and freeze-thaw cycle.

[0104] In this disclosure, the parameters of a simplified microscopic concrete finite element model were set based on the coupling effect parameters. This process reflects the coupling between freeze-thaw cycles and multiaxial stress states, making the subsequent finite element analysis process consistent with the actual stress conditions of concrete and improving the calculation accuracy.

[0105] In one example, the freeze-thaw cycle parameters include the freeze-thaw cycle temperature and the number of freeze-thaw cycles; the parameter setting of the simplified mesoscopic concrete finite element model based on the coupling effect parameters includes:

[0106] The temperature variation range of the pore unit and the concrete unit is determined based on the freeze-thaw cycle temperature.

[0107] The linear expansion coefficient of the pore unit is set according to the temperature change range and the number of freeze-thaw cycles;

[0108] The elastic modulus of the pore unit is set according to the temperature change range.

[0109] The freeze-thaw cycle temperature is a preset temperature range for finite element analysis of the concrete coupling effect, and the temperature variation range is the temperature range within the freeze-thaw cycle temperature range where the coupling effect occurs. The preset freeze-thaw temperature range can be selected as needed. In one example, it can be selected as 8 to -15℃.

[0110] As mentioned earlier, pore elements can effectively reflect the influence of freeze-thaw cycles on concrete components. Specifically, the elastic modulus and linear expansion coefficient of the pore elements can reflect their impact on the concrete component during freeze-thaw cycles. Therefore, setting the parameters of the simplified mesoscopic concrete finite element model based on coupling effect parameters can include setting the elastic modulus and linear expansion coefficient of the pore elements according to freeze-thaw cycle parameters.

[0111] Since freeze-thaw damage to concrete primarily occurs during the freezing process, multiple freeze-thaw cycles can be simplified to a single freeze-thaw cycle. A summary of numerous experimental studies reveals a correlation between the number of freeze-thaw cycles and the linear expansion coefficient of the pore elements. Specifically, for ordinary concrete, the linear expansion coefficient of the pore elements corresponding to 50 freeze-thaw cycles is -0.00003 / ℃, and that for 100 freeze-thaw cycles is -0.00004 / ℃. The linear expansion coefficients of the pore elements at other freeze-thaw cycle numbers can be obtained using the linear interpolation method. In one example, based on the aforementioned relationship between the pore linear expansion coefficient and the number of freeze-thaw cycles, multiple freeze-thaw cycles can be simplified to a single freeze-thaw cycle according to a preset number of cycles. This solves the difficulty in computational convergence caused by a large number of cycles in traditional freeze-thaw cycle analysis, thereby significantly improving computational efficiency.

[0112] Based on the freezing and expansion mechanism of pore water, the pores in concrete only expand within the temperature range of 0 to -70℃, thus causing variations in the linear expansion coefficient of the pore element. Specifically, within the 0 to -70℃ range, the linear expansion coefficient of the pore is defined as negative, while in other temperature ranges, it is taken as the value of ice. Therefore, by determining the different linear expansion coefficients of the pore in different temperature ranges based on the freezing and expansion mechanism of pore water, and combining this with the freeze-thaw cycle temperature range, the amount of freezing expansion of the pore element can be obtained, thereby reflecting the degree of influence of freeze-thaw cycles.

[0113] In addition, the elastic modulus of the pore element can be obtained based on the temperature variation range. Specifically, it can be taken as ice below 0℃, and 0 in the other temperature ranges. The material parameters of the concrete element can be selected according to traditional recommendations, and will not be described in detail here.

[0114] In this disclosure, the linear expansion coefficient and elastic modulus of the pore element are set according to the freeze-thaw cycle temperature and the number of freeze-thaw cycles, so as to realize the influence of freeze-thaw cycle on concrete components in finite element analysis based on the set linear expansion coefficient and elastic modulus of the pore element.

[0115] In one example, setting the parameters of the simplified mesoscopic concrete finite element model based on coupling effect parameters includes:

[0116] Based on the external multiaxial loads or multiaxial constraints applied to the three-dimensional concrete model, loads or constraints are set for the simplified mesoscopic concrete finite element model.

[0117] The coefficient of restitution for compressive stiffness of concrete is defined as 0.6.

[0118] Specifically, the external multiaxial loads or multiaxial constraints applied to the three-dimensional concrete model can be directly converted into loads or constraints applied to the simplified micro-concrete finite element model through the finite element model. Then, loads or constraints are set on the simplified micro-concrete finite element model. Furthermore, finite element analysis can be performed on the simplified micro-concrete finite element model with applied loads or constraints. Based on the analysis results, the coupling effect of the applied external multiaxial loads or multiaxial constraints and the expansion of pore elements on the mechanical properties of the three-dimensional concrete model can be determined.

[0119] Currently, finite element analysis of concrete often employs the birth and death element method (i.e., deleting concrete elements after a certain level of damage) to account for the impact of concrete material damage. However, the traditional birth and death element method cannot account for the actual situation where cracked concrete can still withstand some pressure. In one example, in addition to defining the damage factor, a compressive stiffness recovery coefficient for concrete is also defined to account for the actual situation where cracked concrete can still withstand some pressure during the establishment of the finite element model, thereby improving the accuracy of the simulation method. Specifically, the stiffness recovery coefficient includes: tensile damage stiffness recovery coefficient and compressive damage stiffness recovery coefficient. In one example, based on numerous experimental and trial calculation results, a compressive stiffness recovery coefficient of 0.6 can be defined for concrete, achieving good numerical simulation accuracy.

[0120] S13, Perform finite element analysis of concrete coupling effect on the simplified micro-concrete finite element model after parameter setting. The finite element analysis of concrete coupling effect includes damage analysis of concrete coupling effect and mechanical property analysis after damage of concrete coupling effect.

[0121] The concrete damage caused by the concrete coupling effect can be tensile damage or compressive damage. Correspondingly, in one example, the concrete coupling effect damage analysis can include: the degree and location distribution of compressive damage under the coupling effect of multiaxial stress state and freeze-thaw cycle; and the degree and location distribution of tensile damage under the coupling effect of multiaxial stress state and freeze-thaw cycle. This disclosure, through the degree and location distribution of compressive / tensile damage under the coupling effect of multiaxial stress state and freeze-thaw cycle, can obtain the crack propagation and damage variation law under the coupled action of freeze-thaw cycle and multiaxial stress state.

[0122] After obtaining the concrete coupling effect damage analysis, based on the damaged model, further working conditions can be applied to obtain the material mechanical properties under the corresponding working conditions after the coupled damage. In one example, the analysis of the mechanical properties of the concrete after the coupled damage may include: applying uniaxial or multiaxial loads to the finite element model of the concrete after multiaxial stress state and freeze-thaw cycle coupled damage to obtain the uniaxial or multiaxial mechanical properties of the concrete after the coupled damage; and obtaining a calculation model of the multiaxial stress state and freeze-thaw cycle coupled effect based on the uniaxial or multiaxial mechanical properties of the concrete. This disclosure, based on the damaged model, can further apply working conditions to obtain the material mechanical properties under the corresponding working conditions after the coupled damage.

[0123] The coupling effect finite element analysis refers to performing finite element analysis on the simplified microscopic concrete finite element model after parameter setting. Specifically, the finite element calculation software can be Abaqus, ANSYS, etc. Besides using finite element calculation software to build the finite element model, the finite element model can also be constructed using modeling software such as AutoCAD, SolidWorks, and Pro / E, and then imported into the finite element calculation software for numerical simulation calculation. This disclosure does not impose specific limitations on the selection of modeling software and finite element calculation software; they can be selected according to the actual situation.

[0124] Figure 4 The graph shows the variation of relative compressive strength of concrete under the coupling effect of multiaxial stress and freeze-thaw cycle, obtained by this method. The axial load ratio is calculated as: axial compressive stress / uniaxial compressive strength of unfrozen concrete; the radial load ratio is calculated as: radial compressive stress / uniaxial compressive strength of unfrozen concrete; and the relative compressive strength is calculated as: uniaxial compressive strength of concrete after the coupling effect of multiaxial stress and freeze-thaw cycle / uniaxial compressive strength of unfrozen concrete. Furthermore, a calculation model for the multiaxial stress state and freeze-thaw cycle coupling effect can be obtained based on the obtained uniaxial or multiaxial mechanical properties of concrete. Specifically, a calculation model for the relative compressive strength of concrete after the coupling effect of multiaxial stress and freeze-thaw cycle can be obtained by observing the variation of relative compressive strength of concrete under the coupling effect of multiaxial stress and freeze-thaw cycle. In one example, this calculation model can be expressed by formula (2):

[0125]

[0126] Where α≥0.3 and β≥0.1, It is the relative compressive strength of concrete. α is the relative compressive strength of concrete without stress coupling, α is the axial load ratio, and β is the radial load ratio.

[0127] Figure 5 This is a schematic diagram illustrating the verification results of formula (2) above. Figure 5 It can be seen that the relative compressive strength obtained by formula (2) is in good agreement with the relative compressive strength obtained by experimental measurement. Therefore, it can be concluded that the numerical simulation method of concrete multiaxial stress state and freeze-thaw cycle coupling effect disclosed herein has high accuracy and accurately reflects the influence of complex multiaxial stress state and freeze-thaw cycle coupling effect on concrete model.

[0128] In this embodiment, a simplified micro-concrete finite element model was created, its parameters were set, and finally, a finite element analysis of concrete coupling effects was performed on the simplified micro-concrete finite element model. During the model creation process, dimensional simplification and micro-component simplification techniques were combined. While maintaining the three-dimensional coupling effect analysis function, the model's dimensionality, component complexity, and the difficulty of determining material parameters were reduced, thus significantly reducing the difficulty of creating the micro-concrete finite element model and greatly improving the computational efficiency of numerical simulation while ensuring computational accuracy. During parameter setting, the established model was parameterized according to the coupling effect parameters to further realize the numerical simulation of the coupling effect of multiaxial stress state and freeze-thaw cycle in concrete. This makes the concrete freeze-thaw cycle analysis more consistent with actual stress conditions and improves computational accuracy.

[0129] The above method can quantitatively analyze the mechanical properties of concrete under complex multiaxial stress states and freeze-thaw cycle coupling. It is also applicable to various confined concrete structures such as stirrup-confined concrete, steel tube concrete, and hollow sandwich steel tube concrete. The modeling is simple, the calculation efficiency is high, and it is convenient for engineering applications.

[0130] Application scenario examples

[0131] Confined concrete is the most widely used structural form of concrete. Specifically, confined concrete can include various composite structures such as stirrup-confined concrete, steel tube concrete, and hollow sandwich steel tube concrete. Under this structural form, the concrete material will be under a complex multiaxial stress state for a long time.

[0132] Figure 6 A flowchart illustrating an application example according to this disclosure is shown, such as Figure 6 As shown in the embodiments of this disclosure, a numerical simulation method for concrete under multiaxial stress and freeze-thaw cycle coupling is proposed. This numerical simulation method can realize the numerical simulation analysis of freeze-thaw cycle of steel-tube concrete. The numerical simulation process can be as follows:

[0133] like Figure 6 As shown, the numerical simulation method for freeze-thaw cycles of steel-concrete composite pipes can be roughly divided into three steps.

[0134] Step 1, Model Creation. This includes:

[0135] Using the large-scale general-purpose finite element software Abaqus, and based on dimensional simplification and mesoscopic component simplification techniques, a two-dimensional finite element model of concrete-filled steel tubular material that can reflect three-dimensional properties was established. Figure 7 As shown, this finite element model includes only concrete elements, pore elements, and steel pipe elements.

[0136] The number of pore elements is calculated using formula (1); the specific location of each pore on the concrete element is determined by using the Monte Carlo method and secondary development based on Python; and an embedded constraint method is used between the concrete element and the pore element.

[0137] Step two, parameter settings. This includes:

[0138] Define the material properties of pores, concrete, and steel pipes. Specifically, simplify multiple freeze-thaw cycles to a single freeze-thaw cycle, establish the relationship between the pore linear expansion coefficient and the number of freeze-thaw cycles based on experiments, and define it as a negative value in the range of 0 to -70℃, while taking the value of ice in other temperature ranges; the elastic modulus of the pore element is taken as the value of ice below 0℃, and 0 in other temperature ranges; the constitutive models and material parameters of concrete and steel pipes are selected according to traditional recommendations.

[0139] The concrete element adopts the concrete damage plasticity model, defining tensile damage, compressive damage, compressive stiffness recovery coefficient and tensile stiffness recovery coefficient, wherein the compressive stiffness recovery coefficient of concrete is 0.6.

[0140] Based on the freeze-thaw temperature range, a single temperature change is assigned to all concrete, steel pipe, and pore units.

[0141] Based on the analysis conditions, the normal and tangential contact conditions between the steel tube and the concrete section are defined by applying external axial loads to the steel-concrete composite tube. Specifically, loads are set on the finite element model of the steel-concrete composite tube from step one. Figure 7 This is a finite element model of a steel-concrete composite tube with added loads.

[0142] Step 3, Finite Element Analysis. This includes:

[0143] After performing finite element analysis on the model, the distribution of compressive and tensile damage is output, which can reveal the crack propagation and damage variation of concrete under multiaxial stress state and freeze-thaw cycle coupling. Figure 8 To obtain the damage distribution cloud map from the stress analysis of the finite element model, from Figure 8 It can obtain the crack distribution and damage degree of concrete materials after being subjected to multiaxial stress state and freeze-thaw cycle coupling.

[0144] Based on steel-concrete composite models damaged by freeze-thaw cycles to varying degrees, axial loading can be applied further to obtain the load-displacement curves and compressive strength variation patterns of the steel-concrete composite after freeze-thaw cycles.

[0145] Figure 9 This provides data verification results for the relative compressive strength of concrete members and concrete-tube steel members obtained through the scheme disclosed herein. Figure 9 As shown, the ratio of the simulated to the measured relative compressive strength of concrete members and the ratio of the simulated to the measured relative compressive strength of steel-concrete composite members are both close to 1, which indicates that the scheme disclosed herein better reproduces the analysis process of concrete / steel-concrete composite under multiaxial stress state and freeze-thaw cycle coupling.

[0146] In this embodiment, a simplified micro-concrete finite element model was created, its parameters were set, and finally, a finite element analysis of concrete coupling effects was performed on the simplified micro-concrete finite element model. During model creation, dimensional simplification and micro-component simplification techniques were combined. While maintaining the three-dimensional coupling effect analysis function, the model's dimensional and component complexity was reduced, significantly lowering the difficulty of creating the simplified micro-concrete finite element model and greatly improving the computational efficiency of numerical simulation while ensuring computational accuracy. The embedded constraints of pore elements and concrete elements avoid the repeated trial calculations and corrections of concrete material constitutive parameters required by traditional constraint replacement. Conventional material constitutive parameters can be directly applied, making them easier to determine and more reliable, and more suitable for engineering applications. During parameter setting, the established model was parameterized according to the coupling effect parameters to further realize the numerical simulation of the coupling effect of multiaxial stress state and freeze-thaw cycle in concrete. This makes the concrete freeze-thaw cycle analysis more consistent with actual stress conditions and improves computational accuracy.

[0147] It is understood that the various method embodiments mentioned above in this disclosure can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this disclosure will not elaborate further. Those skilled in the art will understand that in the above methods of specific implementation, the specific execution order of each step should be determined by its function and possible internal logic.

[0148] In addition, this disclosure also provides a numerical simulation device, electronic device, computer-readable storage medium, and program for multiaxial stress state and freeze-thaw cycle coupling effect. All of the above can be used to implement the numerical simulation of any of the concrete multiaxial stress state and freeze-thaw cycle coupling effects provided in this disclosure. The corresponding technical solutions and descriptions are described in the corresponding section of the method and will not be repeated here.

[0149] Figure 10A block diagram of a numerical simulation apparatus for the coupling effect of multiaxial stress state and freeze-thaw cycle in concrete according to an embodiment of the present disclosure is shown. This numerical simulation apparatus for the coupling effect of multiaxial stress state and freeze-thaw cycle in concrete can be a terminal device, a server, or other processing equipment. The terminal device can be a user equipment (UE), mobile device, user terminal, terminal, cellular phone, cordless phone, personal digital assistant (PDA), handheld device, computing device, vehicle-mounted device, wearable device, etc.

[0150] In some possible implementations, the numerical simulation device for the multiaxial stress state of concrete and the coupling effect of freeze-thaw cycles can be implemented by a processor calling computer-readable instructions stored in memory.

[0151] like Figure 10 As shown, the numerical simulation device 100 for the coupling effect of multiaxial stress state and freeze-thaw cycle in concrete may include:

[0152] Model creation module 101 is used to create a simplified micro-concrete finite element model by employing dimensional simplification technology and micro-component simplification technology.

[0153] The parameter setting module 102 is used to set parameters for the simplified micro-concrete finite element model according to the coupling effect parameters, wherein the coupling effect parameters include freeze-thaw cycle parameters and multiaxial stress state parameters.

[0154] The finite element analysis module 103 is used to perform finite element analysis of concrete coupling effect on the simplified micro-concrete finite element model after parameter setting. The finite element analysis of concrete coupling effect includes damage analysis of concrete coupling effect and mechanical property analysis after damage of concrete coupling effect.

[0155] In one possible implementation, the model creation module is used for:

[0156] When the three-dimensional concrete model is cylindrical, the column symmetry technique is used to obtain a two-dimensional finite element model section that can reflect the three-dimensional performance.

[0157] Based on the cross section of the two-dimensional finite element model, an axisymmetric technique is used to obtain a two-dimensional symmetrical finite element model that can reflect three-dimensional performance.

[0158] In one possible implementation, the model creation module is used for:

[0159] On the cross section of the two-dimensional finite element model, only concrete elements and pore elements randomly distributed on the concrete elements are set.

[0160] The pore unit and the concrete unit are constrained by an embedded method.

[0161] In one possible implementation, the freeze-thaw cycle parameters include the freeze-thaw cycle temperature and the number of freeze-thaw cycles; the parameter setting module is used for:

[0162] The temperature variation range of the pore unit and the concrete unit is determined based on the freeze-thaw cycle temperature.

[0163] The linear expansion coefficient of the pore unit is set according to the temperature change range and the number of freeze-thaw cycles;

[0164] The elastic modulus of the pore unit is set according to the temperature change range.

[0165] In one possible implementation, the parameter setting module is used for:

[0166] Based on the external multiaxial loads or multiaxial constraints applied to the three-dimensional concrete model, loads or constraints are set for the simplified mesoscopic concrete finite element model.

[0167] The coefficient of restitution for compressive stiffness of concrete is defined as 0.6.

[0168] In one possible implementation, the concrete coupling effect damage analysis includes:

[0169] The degree and location distribution of compressive damage in concrete under multiaxial stress state and freeze-thaw cycle coupling effect;

[0170] The degree and location distribution of tensile damage under multiaxial stress state and freeze-thaw cycle coupling effect in concrete.

[0171] In one possible implementation, the mechanical property analysis of the concrete after coupling effect damage includes:

[0172] A finite element model of concrete after multiaxial stress state and freeze-thaw cycle coupling damage is subjected to uniaxial or multiaxial loads to obtain the uniaxial or multiaxial mechanical properties of the concrete after coupling damage; based on the uniaxial or multiaxial mechanical properties of the concrete, a calculation model of multiaxial stress state and freeze-thaw cycle coupling effect is obtained.

[0173] This disclosure also proposes a computer-readable storage medium storing computer program instructions that, when executed by a processor, implement the above-described method. The computer-readable storage medium may be a non-volatile computer-readable storage medium.

[0174] This disclosure also proposes an electronic device, including: a processor; and a memory for storing processor-executable instructions; wherein the processor is configured to invoke the instructions stored in the memory to execute the above-described method.

[0175] This disclosure also provides a computer program product including computer-readable code, which, when run on a device, executes instructions for implementing numerical simulations of the multiaxial stress state and freeze-thaw cycle coupling effect of concrete as provided in any of the above embodiments.

[0176] This disclosure also provides another computer program product for storing computer-readable instructions that, when executed, cause the computer to perform the numerical simulation of the multiaxial stress state of concrete and the freeze-thaw cycle coupling effect provided in any of the above embodiments.

[0177] Electronic devices can be provided as terminals, servers, or other forms of devices.

[0178] Figure 11 This diagram illustrates a block diagram of an electronic device 800 according to an embodiment of the present disclosure. For example, the electronic device 800 may be a mobile phone, computer, digital broadcasting terminal, messaging device, game console, tablet device, medical device, fitness equipment, personal digital assistant, or other terminal.

[0179] Reference Figure 11 The electronic device 800 may include one or more of the following components: processing component 802, memory 804, power supply component 806, multimedia component 808, audio component 810, input / output interface 812, sensor component 814, and communication component 816.

[0180] Processing component 802 typically controls the overall operation of electronic device 800, such as operations associated with display, telephone calls, data communication, camera operation, and recording operations. Processing component 802 may include one or more processors 820 to execute instructions to complete all or part of the steps of the methods described above. Furthermore, processing component 802 may include one or more modules to facilitate interaction between processing component 802 and other components. For example, processing component 802 may include a multimedia module to facilitate interaction between multimedia component 808 and processing component 802.

[0181] Memory 804 is configured to store various types of data to support the operation of electronic device 800. Examples of this data include instructions for any application or method operating on electronic device 800, contact data, phonebook data, messages, pictures, videos, etc. Memory 804 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0182] Power supply component 806 provides power to various components of electronic device 800. Power supply component 806 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power to electronic device 800.

[0183] Multimedia component 808 includes a screen that provides an output interface between the electronic device 800 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touchscreen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensors may sense not only the boundaries of the touch or swipe action but also the duration and pressure associated with the touch or swipe operation. In some embodiments, multimedia component 808 includes a front-facing camera and / or a rear-facing camera. When the electronic device 800 is in an operating mode, such as a shooting mode or a video mode, the front-facing camera and / or the rear-facing camera may receive external multimedia data. Each front-facing camera and rear-facing camera may be a fixed optical lens system or have focal length and optical zoom capabilities.

[0184] Audio component 810 is configured to output and / or input audio signals. For example, audio component 810 includes a microphone (MIC) configured to receive external audio signals when electronic device 800 is in an operating mode, such as call mode, recording mode, and voice recognition mode. The received audio signals may be further stored in memory 804 or transmitted via communication component 816. In some embodiments, audio component 810 also includes a speaker for outputting audio signals.

[0185] Input / output interface 812 provides an interface between processing component 802 and peripheral interface modules, such as keyboards, click wheels, buttons, etc. These buttons may include, but are not limited to, home buttons, volume buttons, start buttons, and lock buttons.

[0186] Sensor assembly 814 includes one or more sensors for providing state assessments of various aspects of electronic device 800. For example, sensor assembly 814 can detect the on / off state of electronic device 800, the relative positioning of components such as the display and keypad of electronic device 800, changes in position of electronic device 800 or a component of electronic device 800, the presence or absence of user contact with electronic device 800, orientation or acceleration / deceleration of electronic device 800, and temperature changes of electronic device 800. Sensor assembly 814 may include a proximity sensor configured to detect the presence of nearby objects without any physical contact. Sensor assembly 814 may also include a light sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, sensor assembly 814 may also include an accelerometer, gyroscope, magnetometer, pressure sensor, or temperature sensor.

[0187] Communication component 816 is configured to facilitate wired or wireless communication between electronic device 800 and other devices. Electronic device 800 can access wireless networks based on communication standards, such as WiFi, 2G, or 3G, or combinations thereof. In one exemplary embodiment, communication component 816 receives broadcast signals or broadcast-related information from an external broadcast management system via a broadcast channel. In one exemplary embodiment, communication component 816 also includes a near-field communication (NFC) module to facilitate short-range communication. For example, the NFC module may be implemented based on radio frequency identification (RFID) technology, Infrared Data Association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0188] In an exemplary embodiment, the electronic device 800 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to perform the methods described above.

[0189] In an exemplary embodiment, a non-volatile computer-readable storage medium is also provided, such as a memory 804 including computer program instructions that can be executed by a processor 820 of an electronic device 800 to perform the above-described method.

[0190] Figure 12 A block diagram of an electronic device 1900 according to an embodiment of the present disclosure is shown. For example, the electronic device 1900 may be provided as a server. (Refer to...) Figure 12The electronic device 1900 includes a processing component 1922, which further includes one or more processors, and memory resources represented by memory 1932 for storing instructions, such as application programs, that can be executed by the processing component 1922. The application programs stored in memory 1932 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 1922 is configured to execute instructions to perform the methods described above.

[0191] Electronic device 1900 may also include a power supply component 1926 configured to perform power management of electronic device 1900, a wired or wireless network interface 1950 configured to connect electronic device 1900 to a network, and an input / output interface 1958. Electronic device 1900 can operate on an operating system, such as Windows Server, stored in memory 1932. TM Mac OS X TM Unix TM Linux TM FreeBSD TM Or similar.

[0192] In an exemplary embodiment, a non-volatile computer-readable storage medium is also provided, such as a memory 1932 including computer program instructions that can be executed by a processing component 1922 of an electronic device 1900 to perform the above-described method.

[0193] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0194] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0195] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0196] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, Python, Java, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing state information from the computer-readable program instructions. This electronic circuitry can execute the computer-readable program instructions to implement various aspects of this disclosure.

[0197] Various aspects of this disclosure are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-readable program instructions.

[0198] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processor of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner; thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing aspects of the functions / actions specified in one or more blocks of the flowchart and / or block diagram.

[0199] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.

[0200] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0201] The computer program product can be implemented specifically through hardware, software, or a combination thereof. In one alternative embodiment, the computer program product is specifically embodied in a computer storage medium; in another alternative embodiment, the computer program product is specifically embodied in a software product, such as a software development kit (SDK), etc.

[0202] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A numerical simulation method for the multiaxial stress state and freeze-thaw cycle coupling effect of concrete, characterized in that, include: A simplified micro-concrete finite element model was created using dimensional simplification and meso-component simplification techniques. Based on the coupling effect parameters, the parameters of the simplified micro-concrete finite element model are set, including freeze-thaw cycle parameters and multiaxial stress state parameters. A finite element analysis of concrete coupling effect is performed on the simplified micro-concrete finite element model after parameter setting. The finite element analysis of concrete coupling effect includes damage analysis of concrete coupling effect and mechanical property analysis after damage of concrete coupling effect. The method employs dimensional simplification and mesoscopic component simplification techniques to create a simplified mesoscopic concrete finite element model, including: When the three-dimensional concrete model is cylindrical, the column symmetry technique is used to obtain a two-dimensional finite element model section that can reflect the three-dimensional performance. Based on the cross section of the two-dimensional finite element model, an axisymmetric technique is used to obtain a two-dimensional symmetric finite element model that can reflect three-dimensional performance. The method employs dimensional simplification and mesoscopic component simplification techniques to create a simplified mesoscopic concrete finite element model, including: On the cross section of the two-dimensional finite element model, only concrete elements and pore elements randomly distributed on the concrete elements are set. The pore unit and the concrete unit are constrained by an embedded method.

2. The method according to claim 1, characterized in that, The freeze-thaw cycle parameters include the freeze-thaw cycle temperature and the number of freeze-thaw cycles; The parameter setting of the simplified mesoscopic concrete finite element model based on the coupling effect parameters includes: The temperature variation range of the pore unit and the concrete unit is determined based on the freeze-thaw cycle temperature. The linear expansion coefficient of the pore unit is set according to the temperature change range and the number of freeze-thaw cycles; The elastic modulus of the pore unit is set according to the temperature change range.

3. The method according to claim 1, characterized in that, The parameter setting of the simplified mesoscopic concrete finite element model based on the coupling effect parameters includes: Based on the external multiaxial loads or multiaxial constraints applied to the three-dimensional concrete model, loads or constraints are set for the simplified mesoscopic concrete finite element model. The coefficient of restitution for compressive stiffness of concrete is defined as 0.

6.

4. The method according to claim 1, characterized in that, The concrete coupling effect damage analysis includes: The degree and location distribution of compressive damage in concrete under multiaxial stress state and freeze-thaw cycle coupling effect; The degree and location distribution of tensile damage under multiaxial stress state and freeze-thaw cycle coupling effect in concrete.

5. The method according to claim 1, characterized in that, The mechanical property analysis of the concrete after coupling effect damage includes: By applying uniaxial or multiaxial loads to the finite element model of concrete under multiaxial stress state and damage caused by freeze-thaw cycle coupling effect, the uniaxial or multiaxial mechanical properties of concrete after damage caused by coupling effect are obtained. Based on the uniaxial or multiaxial mechanical properties of the concrete, a calculation model for the multiaxial stress state and freeze-thaw cycle coupling effect is obtained.

6. A numerical simulation device for the coupling effect of multiaxial stress state and freeze-thaw cycle in concrete, characterized in that, include: The model creation module is used to create simplified micro-concrete finite element models using dimensional simplification and meso-component simplification techniques. The parameter setting module is used to set parameters for the simplified micro-concrete finite element model based on the coupling effect parameters, which include freeze-thaw cycle parameters and multiaxial stress state parameters. The finite element analysis module is used to perform finite element analysis of concrete coupling effects on the simplified micro-concrete finite element model after parameter setting. The finite element analysis of concrete coupling effects includes damage analysis of concrete coupling effects and mechanical property analysis of concrete after damage due to concrete coupling effects. The model creation module is used for: When the three-dimensional concrete model is cylindrical, the column symmetry technique is used to obtain a two-dimensional finite element model section that can reflect the three-dimensional performance. Based on the cross section of the two-dimensional finite element model, an axisymmetric technique is used to obtain a two-dimensional symmetric finite element model that can reflect three-dimensional performance. The model creation module is used for: On the cross section of the two-dimensional finite element model, only concrete elements and pore elements randomly distributed on the concrete elements are set. The pore unit and the concrete unit are constrained by an embedded method.

7. An electronic device, characterized in that, include: processor; Memory used to store processor-executable instructions; The processor is configured to implement the method of any one of claims 1 to 5 when executing instructions stored in the memory.

8. A non-volatile computer-readable storage medium storing computer program instructions thereon, characterized in that, When the computer program instructions are executed by the processor, they implement the method described in any one of claims 1 to 5.

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