Method, system and equipment for predicting creep stress at joint of concrete structure and medium

Abstract

The invention relates to a method, a system and equipment for predicting creep stress at a joint of a concrete structure and a medium. The method comprises the following steps: testing a concrete structure material and a concrete structure joint filling material, and constructing a joint material performance database based on test data; constructing a multi-scale mechanical model comprising a macrostructure model and a microcosmic interface model based on the seam material performance database; constructing an interface constitutive relationship based on the seam material performance database and the multi-scale mechanical model; and predicting the creep stress at the joint of the concrete structure based on the material performance database at the joint, the multi-scale mechanical model and the interface constitutive relationship. The method can fully consider the sudden change of the performance of the material at the joint and the interface effect, provides reliable technical support for the safety evaluation and maintenance of the concrete structure, and is particularly suitable for engineering application of large-span and high-rise buildings and the like with higher requirements on the long-term performance of the structure.

Description

Technical Field

[0001] This application relates to the field of concrete creep stress prediction technology, and in particular to a method, system, equipment and medium for predicting creep stress at concrete structure joints. Background Technology

[0002] Predicting creep stress at joints is a critical technical challenge in concrete structural engineering. The creep characteristics of concrete lead to stress redistribution under long-term loads, particularly at joints where stress changes are more complex. Traditional prediction methods, primarily based on empirical formulas or simplified mechanical models, struggle to accurately reflect the complex stress state at joints, resulting in significant discrepancies between predicted and actual stress states. This complicates structural safety assessments and maintenance decisions. Summary of the Invention

[0003] Therefore, it is necessary to provide a method, system, equipment, and medium for predicting creep stress at joints in concrete structures to address the aforementioned technical problems.

[0004] In a first aspect, this application provides a method for predicting creep stress at concrete structure joints. The method includes: testing concrete structural materials and joint filler materials; constructing a joint material performance database based on the test data; constructing a multi-scale mechanical model including a macroscopic structural model and a microscopic interface model based on the joint material performance database; constructing an interface constitutive relation based on the joint material performance database and the multi-scale mechanical model; and predicting the creep stress at the concrete structure joint based on the joint material performance database, the multi-scale mechanical model, and the interface constitutive relation.

[0005] Optionally, the test data for the concrete structural material includes: the elastic modulus of the concrete structural material, the creep coefficient of the concrete structural material, and the shrinkage coefficient of the concrete structural material; the test data for the filler material at the concrete joint includes: the elastic modulus of the filler material, the creep coefficient of the filler material, the shrinkage coefficient of the filler material, the bond strength of the filler material, and the fracture toughness of the filler material.

[0006] Optionally, a multi-scale mechanical model including a macroscopic structural model and a microscopic interface model is constructed based on the material property database at the joint. This includes: constructing a macroscopic structural model; constructing a microscopic structural model; establishing a transition zone between the macroscopic structural model and the microscopic structural model based on the Arlequin coupling algorithm to obtain a coupled model between the macroscopic structural model and the microscopic structural model; establishing a material response surface surrogate model based on the coupled model to obtain a parameter transfer mechanism; setting a solution strategy based on the arc length control method; and outputting a multi-scale mechanical model including the macroscopic structural model, the microscopic structural model, the coupled model, the parameter transfer mechanism, and the solution strategy.

[0007] Optionally, constructing a macroscopic structural model includes: discretizing the concrete structure using 8-node hexahedral elements; retrieving the elastic modulus of the concrete structural material from the material property database at the joints, and using the Weibull distribution to describe the spatial distribution of the elastic modulus of the concrete structural material; and applying load boundary conditions to obtain the macroscopic structural model.

[0008] Optionally, a microstructure model is constructed, including: establishing a locally densified sub-model at the joint of the concrete structure; implanting zero-thickness interface elements at the contact surface of the filling material at the joint between the concrete structures; and initially calibrating the bilinear softening model parameters of the interface elements using the bond strength and fracture toughness from the material property database at the joint.

[0009] Optionally, constructing the interface constitutive relation based on the joint material property database and the multi-scale mechanical model includes: using an improved Park-Paulino bilinear constitutive model as the basic framework and introducing a creep effect correction term to obtain a one-dimensional multi-mechanism coupled constitutive framework; extending the one-dimensional multi-mechanism coupled constitutive framework into a three-dimensional multi-mechanism coupled constitutive framework; correcting the three-dimensional multi-mechanism coupled constitutive framework using a humidity diffusion equation to obtain a three-dimensional multi-mechanism coupled constitutive framework containing humidity coupling; and performing parameter inversion on the three-dimensional multi-mechanism coupled constitutive framework containing humidity coupling using an improved differential evolution algorithm to obtain the interface constitutive relation.

[0010] Optionally, predicting the creep stress at the joint of a concrete structure based on the joint material property database, the multi-scale mechanical model, and the interface constitutive relation includes: performing time discretization processing based on the joint material property database to obtain a time step sequence and basic parameters for strain decomposition at each step; obtaining the joint stress, slip, and strain energy density at the current step based on the time step sequence, the basic parameters for strain decomposition at each step, and the interface constitutive relation; performing multi-scale stress transfer based on the joint stress, the slip, and the strain energy density to obtain the stress tensor of the macroscopic structure; obtaining the joint micro-stress and macroscopic structural stress at the current time step based on the stress tensor of the macroscopic structure; and predicting the creep stress at the joint of the concrete structure based on the joint micro-stress and macroscopic structural stress at the current time step.

[0011] Secondly, this application also provides a system for predicting creep stress at concrete structure joints. The system includes: a joint material performance database construction module for testing concrete structural materials and joint filling materials, and constructing a joint material performance database based on the test data; a multi-scale mechanical model construction module for constructing a multi-scale mechanical model including a macroscopic structural model and a microscopic interface model based on the joint material performance database; an interface constitutive relation construction module for constructing an interface constitutive relation based on the joint material performance database and the multi-scale mechanical model; and a concrete structure joint creep stress prediction module for predicting creep stress at concrete structure joints based on the joint material performance database, the multi-scale mechanical model, and the interface constitutive relation.

[0012] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of any of the above-described methods for predicting creep stress at joints of concrete structures.

[0013] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the above-described methods for predicting creep stress at joints in concrete structures.

[0014] The aforementioned method, system, equipment, and medium for predicting creep stress at concrete structure joints involve testing concrete structural materials and joint filler materials, constructing a joint material performance database based on the test data, building a multi-scale mechanical model including macroscopic structural and microscopic interface models based on this database, establishing interface constitutive relations based on the database and the multi-scale mechanical model, and predicting creep stress at concrete structure joints based on these conditions. This approach fully considers abrupt changes in joint material properties and interface effects, providing reliable technical support for the safety assessment and maintenance of concrete structures, and is particularly suitable for engineering applications with high long-term structural performance requirements, such as large-span and high-rise buildings. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a method for predicting creep stress at concrete structure joints provided in one embodiment.

[0016] Figure 2 A structural block diagram of a concrete structure joint creep stress prediction system provided in another embodiment;

[0017] Figure 3 This is an internal structural diagram of a computer device provided in yet another embodiment. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] In one embodiment, such as Figure 1 As shown, this application provides a method for predicting creep stress at joints in concrete structures. The method for predicting creep stress at joints in concrete structures may include the following steps: S10~S40.

[0020] S10: Test concrete structural materials and concrete joint filling materials, and build a database of joint material performance based on the test data.

[0021] S20: Construct a multi-scale mechanical model, including a macroscopic structural model and a microscopic interface model, based on the material property database of the joint.

[0022] S30: Construct the interface constitutive relation based on the material property database of the joint and the multi-scale mechanical model.

[0023] S40: Based on the material property database of the joint, the multi-scale mechanical model, and the interface constitutive relation, predict the creep stress at the joint of the concrete structure.

[0024] The method for predicting creep stress at concrete joints in this application involves several steps: testing the concrete structural materials and the filling materials at the concrete joints; constructing a material performance database for the joints based on the test data; building a multi-scale mechanical model, including a macroscopic structural model and a microscopic interface model, based on the joint material performance database; constructing an interface constitutive relation based on the joint material performance database and the multi-scale mechanical model; and predicting the creep stress at the concrete joints based on the joint material performance database, the multi-scale mechanical model, and the interface constitutive relation. This method fully considers the abrupt changes in material properties and interface effects at the joints, providing reliable technical support for the safety assessment and maintenance of concrete structures. It is particularly suitable for engineering applications with high requirements for long-term structural performance, such as large-span and high-rise buildings.

[0025] In step S10, please refer to Figure 1 In step S10, the concrete structural materials and the filling materials at the joints of the concrete structure are tested, and a database of joint material performance is constructed based on the test data.

[0026] As an example, the test data for the concrete structural material includes: the elastic modulus of the concrete structural material, the creep coefficient of the concrete structural material, and the shrinkage coefficient of the concrete structural material; the test data for the filler material at the joint of the concrete structure includes: the elastic modulus of the filler material, the creep coefficient of the filler material, the shrinkage coefficient of the filler material, the bond strength of the filler material, and the fracture toughness of the filler material.

[0027] As an example, for concrete structures, it is necessary to determine the elastic modulus of concrete at 28 days of age (an index representing the ability of concrete to resist elastic deformation), the creep coefficient of concrete (describing the deformation characteristics of concrete under continuous load as time increases), and the shrinkage coefficient of concrete (reflecting the degree of volume shrinkage of concrete due to moisture evaporation).

[0028] As an example, for the filling materials at the joints of concrete structures (such as epoxy resin, polyurethane, or cement-based grout), it is also necessary to measure the elastic modulus, creep coefficient, and shrinkage coefficient of the filling material at 28 days of age, as well as the bond strength and fracture toughness of the filling material.

[0029] Specifically, the modulus of elasticity can be determined by compression tests, recording the initial linear slope of the stress-strain curve; the creep coefficient can be determined by sustained loading tests, recording the deformation of the specimen (concrete structure or infill material) under constant load over time; and the shrinkage coefficient can be determined by drying shrinkage tests, recording the length change of the specimen under standard conditions.

[0030] As an example, the material performance database for the joint can adopt a hierarchical structure design. The first layer contains basic material information (type, manufacturer, batch, etc.), the second layer contains basic mechanical parameters (elastic modulus and strength, etc.), the third layer contains time-related parameters (creep coefficient and shrinkage coefficient, etc.), and the fourth layer contains environmentally dependent parameters (temperature and humidity influence coefficients, etc.).

[0031] In step S20, please refer to Figure 1 In step S20, a multi-scale mechanical model including a macroscopic structural model and a microscopic interface model is constructed based on the material property database of the joint.

[0032] As an example, in step S20, constructing a multi-scale mechanical model including a macroscopic structural model and a microscopic interface model based on the material property database of the joint can include the following steps: S201~S206.

[0033] S201: Construct a macroscopic structural model.

[0034] S202: Construct a microstructure model.

[0035] S203: Establish the transition region between the macroscopic structural model and the microscopic structural model based on the Arlequin coupling algorithm to obtain the coupling model between the macroscopic structural model and the microscopic structural model.

[0036] S204: Establish a material response surface proxy model based on the coupling model to obtain the parameter transfer mechanism.

[0037] S205: Set the solution strategy based on the arc length control method.

[0038] S206: Output a multi-scale mechanical model that includes macroscopic structural models, microscopic structural models, coupling models, parameter transfer mechanisms, and solution strategies.

[0039] As an example, in step S201, constructing a macroscopic structural model may include the following steps: S2011~S2013.

[0040] S2011: A discrete concrete structure using 8-node hexahedral elements.

[0041] S2012: Retrieve the elastic modulus of the concrete structural material from the material property database at the joint, and use the Weibull distribution to describe the spatial distribution of the elastic modulus of the concrete structural material.

[0042] S2013: Apply load boundary conditions to obtain the macroscopic structural model.

[0043] Specifically, in step S201, the mesh size of the constructed macroscopic structure network is controlled to be 1 / 5 to 1 / 10 of the minimum feature size of the structure.

[0044] Specifically, in step S2012, considering spatial variability, the Weibull distribution is used to describe the spatial distribution of the elastic modulus of concrete structural materials. The corresponding formula can be as follows:

[0045]

[0046] Where E0 is the nominal elastic modulus; φ is a uniformly distributed random number in the range of [0,1]; and m is the shape parameter, which is 6 to 10 for concrete.

[0047] Specifically, in step S2013, the load boundary conditions can be applied according to the actual working conditions, and may include, but are not limited to, self-weight, live load, and prestress, etc.

[0048] As an example, in step S202, constructing a microstructure model may include the following steps: S2021~S2023.

[0049] S2021: Establish a locally encrypted sub-model at the joints of the concrete structure.

[0050] S2022: Zero-thickness interface elements are implanted at the contact surface of the filling material at the joint between concrete structures.

[0051] S2023: The bilinear softening model parameters of the interface unit are initially calibrated using the bond strength and fracture toughness from the material property database of the joint.

[0052] Specifically, in step S2021, the local densification sub-model can be established at the joint of the concrete structure within a range of 3 to 5 times the thickness, and can be refined using 2-node elements.

[0053] Specifically, in step S2022, seam behavior is simulated by implanting zero-thickness interface units.

[0054] Specifically, in step S2023, the formula for the bilinear softening model can be as follows:

[0055]

[0056] Where τ is the interfacial shear stress; δ is the interfacial slip; k0 is the initial interfacial stiffness; δ0 is the elastic limit slip; τ max τ represents the peak bond strength. r Residual bond strength; δ f This represents the limit slip.

[0057] As an example, in step S203, a transition zone can be set between the macroscopic structure model and the microscopic structure model. The width of the transition zone can be 2 to 3 times the size of the microscopic mesh (for example, if the size of the microscopic mesh is 20 nm, the width of the transition zone can be 40 to 60 nm) to achieve a gradual transition from the macroscopic coarse mesh to the microscopic fine mesh and avoid computational distortion caused by abrupt mesh changes.

[0058] As an example, in step S203, a mixing domain can be established in the transition region based on the Arlequin algorithm, and the corresponding formula is as follows:

[0059]

[0060]

[0061] in, The macroscopic energy weighting coefficient represents the proportion of energy contribution of the macroscopic structural model in the transition region; d is the micro-energy weighting coefficient, representing the proportion of energy contribution of the micro-structure model in the transition zone; d is the spatial distance variable, i.e., the distance from any point in the transition zone to the concrete structure joint; d0 is the distance from the center of the transition zone to the concrete structure joint; k is the weight change rate coefficient.

[0062] As an example, in step S204, a training material response surface surrogate model can be established based on a large amount of calculation results from the microscopic model. The formula for training the material response surface surrogate model can be as follows:

[0063]

[0064] in, ε is the microscopic response; t is the macroscopic strain; T is time; H is temperature; and n is the number of basis function terms. Let i be the weight coefficient of the i-th term; Let i be the strain influence function; Let i be the time influence function of the i-th term; Let i be the temperature influence function; Let be the humidity influence function for the i-th term.

[0065] As an example, in step S205, the improved Newton-Raphson iterative method can be used to solve the nonlinear equations, and the arc length control method can be introduced to handle the softening stage. The corresponding formula is as follows:

[0066]

[0067] in, This is the arc length step size factor; Preset arc length; For the position increment norm; This is the load-displacement weighting factor; For the force increment norm.

[0068] In step S30, please refer to Figure 1 In step S30, the interface constitutive relation is constructed based on the material property database of the joint and the multi-scale mechanical model.

[0069] As an example, in step S30, constructing the interface constitutive relationship based on the joint material property database and the multi-scale mechanical model may include the following steps: S301~S304.

[0070] S301: Based on the material property database of the joint and the multi-scale mechanical model, an improved Park-Paulino bilinear constitutive model is adopted as the basic framework, and a creep effect correction term is introduced to obtain a one-dimensional multi-mechanism coupled constitutive framework.

[0071] S302: Extend the one-dimensional multi-mechanism coupling constitutive framework into a three-dimensional multi-mechanism coupling constitutive framework.

[0072] S303: The three-dimensional multi-mechanism coupling constitutive framework is modified by the humidity diffusion equation to obtain a three-dimensional multi-mechanism coupling constitutive framework with humidity coupling.

[0073] S304: An improved differential evolution algorithm is used to perform parameter inversion on a three-dimensional multi-mechanism coupled constitutive framework containing humidity coupling in order to obtain the interface constitutive relation.

[0074] As an example, in step S301, the improved Park-Paulino bilinear constitutive model is used as the basic framework, and a creep effect correction term is introduced to obtain the formula corresponding to the one-dimensional multi-mechanism coupled constitutive framework, which can be:

[0075] .

[0076] Where τ is the total interfacial shear stress; τ mech For mechanical shear stress; τ creep δ is the creep shear stress; k0 is the interface slip; k is the initial interface stiffness;c τ is the stiffness creep attenuation coefficient; n is the stiffness attenuation time exponent; δ0 is the elastic limit slip; τ max β is the peak bond strength; β is the peak strength creep decay coefficient; m is the peak decay time exponent; τ r Residual bond strength; δ f γ is the limiting slip; p is the residual strength creep attenuation coefficient; t is the residual attenuation time exponent; and t is the service time.

[0077] As an example, the improved Park-Paulino bilinear constitutive model takes into account both instantaneous mechanical losses and long-term creep effects.

[0078] As an example, in step S302, a three-dimensional stress-displacement matrix can be established, and the corresponding formula is as follows:

[0079]

[0080] in, This represents the interface stress vector. The normal vector shear stress; The shear stress is tangential. The tangential shear stress is s. For damage correction stiffness matrix; k n k is the initial normal stiffness. t Let k be the initial stiffness along the tangential direction t; s Let D be the initial stiffness along the tangential direction s; t For tangential t-damage variables; D s For tangential s-damage variables; The relative displacement vector of the interface; This represents the relative displacement of the interface along the normal direction. This represents the relative displacement of the interface along the tangential direction t; The tangential s-interface relative displacement.

[0081] As an example, the formula for the damage variable can be as follows:

[0082]

[0083] Among them, D i Let G be the damage variable in direction i (which can be normal n, tangential t, or tangential s); fi Let G be the initial fracture energy in direction i; di Let G be the energy dissipated by damage in direction i. di The formula can be expressed as follows:

[0084] in, The direction i represents the relative displacement of the interface. Let i be the shear stress in the direction of y.

[0085] As an example, step S303 may include introducing a humidity diffusion equation to correct the three-dimensional multi-mechanism coupling constitutive framework, and the corresponding formula may be as follows:

[0086]

[0087] Where k is a material parameter; Let be the rate of change of material parameter k over time; t be time; D be the time factor. h The humidity diffusion coefficient; Let h be the Laplace operator for humidity; h is the current humidity. To balance the adjustment rate coefficient; h eq To balance humidity.

[0088] As an example, in step S303, humidity affects the three-dimensional multi-mechanism coupling constitutive framework through the following formula:

[0089]

[0090] Where, k wet Material parameters under humid conditions; k day Here are the material parameters in the dry state; h0 is the ambient relative humidity; η is the maximum attenuation coefficient. This is the temperature sensitivity index.

[0091] As an example, in step S304, the formula for parameter inversion of a three-dimensional multi-mechanism coupled constitutive framework containing humidity coupling using the improved differential evolution algorithm can be as follows:

[0092]

[0093] As an example, For new parameter combinations (new candidate solutions); The current optimal parameter combination (global optimal solution); F is the differential scaling factor; This is the first random candidate solution; This is the second random candidate solution; This is a local adjustment factor (i.e., adaptive weight); This is a locally optimal solution; This is a local worst-case solution. The formula innovatively incorporates an elite-oriented term. .

[0094] Specifically, local regulatory factors The formula can be expressed as follows:

[0095]

[0096] in, This represents the current iteration number; This represents the maximum number of iterations. Pi is the mathematical constant of a circle.

[0097] In step S40, please refer to Figure 1 In step S40, the creep stress at the joint of the concrete structure is predicted based on the material property database at the joint, the multi-scale mechanical model, and the interface constitutive relation.

[0098] As an example, in step S40, predicting the creep stress at the joint of a concrete structure based on the joint material property database, the multi-scale mechanical model, and the interface constitutive relation may include the following steps: S401~S405.

[0099] S401: Based on the material property database of the joint, perform time discretization processing to obtain the time step sequence and the basic parameters of strain decomposition for each step.

[0100] S402: Based on the time step sequence, the basic parameters of strain decomposition at each step, and the interface constitutive relation, obtain the joint stress, slip, and strain energy density of the current step.

[0101] S403: Multi-scale stress transfer is performed based on the joint stress, the slip amount, and the strain energy density to obtain the stress tensor of the macroscopic structure.

[0102] S404: Based on the stress tensor of the macrostructure, obtain the joint micro-stress and macro-structure stress at the current time step.

[0103] S405: Predict creep stress at concrete joints based on micro and macro structural stresses at the current time step.

[0104] As an example, in step S401, the long-term creep process can be discretized into N short-duration periods, and the corresponding formulas are as follows:

[0105]

[0106] in, Let k be the dynamic time step size. This is the maximum allowed time step. Used as the reference time step; t is the step size adjustment factor; k t represents the time corresponding to the k-th step. ref This is the reference time for the step size.

[0107] As an example, the strain increment decomposition is performed within each time step as follows:

[0108]

[0109] in, This represents the total strain increment; This represents the elastic strain increment; For creep strain increment; This represents the contraction strain increment.

[0110] Specifically, elastic strain increment It can be calculated using Hooke's Law.

[0111] Specifically, creep strain increment An improved B3 model can be used, and the corresponding formula is as follows:

[0112]

[0113] in, These are parameters representing the creep characteristics of the material. t represents the instantaneous applied stress; t represents the cumulative service time. This is the stress sensitivity index term; This is a short-term creep correction term; For time intervals.

[0114] Specifically, the contraction strain increment The ACI209 model can be used for correction, and the corresponding formula is as follows:

[0115]

[0116] in, t is the drying shrinkage limit strain; h is the cumulative drying time; 1.018 is the ambient relative temperature; and 1.018 is the temperature influence coefficient.

[0117] As an example, in step S402, the interface elements at the concrete structure joints are processed using a hybrid update algorithm, and the corresponding formula can be as follows:

[0118]

[0119] in, Let n be the interfacial stress at step n+1; E represents the interfacial stress at step n. c It is the interfacial elastic modulus; This represents the total strain increment; For creep strain increment; This is a stress relaxation term; The relaxation coefficient; For time step; This is a slip degradation term; This is the slip influence coefficient; This represents the absolute value of the slip increment.

[0120] As an example, for a three-dimensional state, the strain energy density can be obtained using the equivalent strain energy density criterion, and the corresponding formula is as follows:

[0121]

[0122] Among them, W eq W represents the strain energy density. n W represents the normal energy density. t W represents the tangential energy density at t. s α is the tangential s-energy density; α is the tangential weighting coefficient.

[0123] Specifically, when W eq ≥W cr When this happens, a state transition is triggered; among which, W cr It is the critical equivalent work.

[0124] As an example, in step S403, a higher-order homogenization method can be used to achieve the transfer of macroscopic stress and microscopic stress, and the corresponding formula is as follows:

[0125]

[0126] in, V represents the macroscopic stress; V represents the volume of the microstructure model. Microscopic stress; The symbol for Kronecker; For microscopic perturbation displacement field; For microscopic coordinates; The gradient represents the microscopic displacement perturbation.

[0127] As an example, in step S404, the Newton-Raphson iteration method can be used to introduce arc length control to improve convergence, reduce residual force, and approximate the equilibrium state. The specific formula is as follows:

[0128]

[0129] in, This represents the displacement increment at step k+1. This represents the displacement increment at step k. This is the tangent stiffness matrix at step k; I is the arc length parameter; I is the identity matrix; Let be the residual vector at step k.

[0130] Specifically, arc length parameter It can be automatically adjusted based on the current stiffness, and the corresponding formula is as follows:

[0131]

[0132] in, This refers to the initial arc length parameter; Let the initial residual norm be denoted as . Let be the residual norm at step k; This represents the displacement step size for the current iteration step. This is the initial displacement step size.

[0133] Specifically, when <10 -5 When N is reached, convergence is determined, and the micro-stress of the joint and the macro-stress of the structure at the current time step are output.

[0134] As an example, in step S405, steps S402 to S404 can be repeated to traverse all time steps, sort the joint micro-stress of all time steps by time, and connect them to form a curve, thus obtaining the predicted stress curve of creep stress at the joint of the concrete structure.

[0135] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0136] In one embodiment, such as Figure 2As shown, a system for predicting creep stress at concrete structure joints is provided. This system may include: a joint material property database construction module 10, a multi-scale mechanical model construction module 20, an interface constitutive relation construction module 30, and a concrete structure joint creep stress prediction module 40. The joint material property database construction module 10 is used to test concrete structural materials and concrete joint filling materials, and construct a joint material property database based on the test data. The multi-scale mechanical model construction module 20 is used to construct a multi-scale mechanical model, including a macroscopic structural model and a microscopic interface model, based on the joint material property database. The interface constitutive relation construction module 30 is used to construct an interface constitutive relation based on the joint material property database and the multi-scale mechanical model. The concrete structure joint creep stress prediction module 40 is used to predict the creep stress at concrete structure joints based on the joint material property database, the multi-scale mechanical model, and the interface constitutive relation.

[0137] Specific limitations regarding the creep stress prediction system for concrete structure joints can be found in the limitations of the creep stress prediction method for concrete structure joints mentioned above, and will not be repeated here. Each module in the aforementioned creep stress prediction system for concrete structure joints can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0138] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 3 As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and database. The internal memory provides the environment for the operation of the operating system and computer programs in the non-volatile storage media. The database stores flight attitude and positioning data of the eVTOL aircraft, ground station databases, real-time communication parameters, and other data. The network interface is used for communication with external terminals via a network connection. When executed by the processor, the computer program implements a method for predicting creep stress at joints in concrete structures.

[0139] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 3As shown, the computer device includes a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface is used to communicate with external terminals via a network connection. When executed by the processor, the computer program implements a method for predicting creep stress at joints in concrete structures. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device casing, or an external keyboard, touchpad, or mouse.

[0140] Those skilled in the art will understand that Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0141] In one embodiment, a computer device is provided, including a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement, for example... Figure 1 The steps of the method for predicting creep stress at concrete structure joints in the corresponding embodiments.

[0142] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program implementing, when executed by a processor, as shown in the figure. Figure 1 The steps of the method for predicting creep stress at concrete structure joints in the corresponding embodiments.

[0143] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0144] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0145] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for predicting creep stress at joints in concrete structures, characterized in that, include: Tests were conducted on concrete structural materials and filling materials at concrete joints, and a database of joint material performance was constructed based on the test data. A multi-scale mechanical model, including macroscopic structural models and microscopic interface models, is constructed based on the aforementioned joint material property database. The interface constitutive relation is constructed based on the material property database of the joint and the multi-scale mechanical model. The creep stress at the joint of concrete structure is predicted based on the material property database of the joint, the multi-scale mechanical model, and the interface constitutive relation.

2. The method according to claim 1, characterized in that, The test data for the concrete structural materials include: the elastic modulus of the concrete structural materials, the creep coefficient of the concrete structural materials, and the shrinkage coefficient of the concrete structural materials. Test data for infill materials at concrete joints include: elastic modulus, creep coefficient, shrinkage coefficient, bond strength, and fracture toughness of the infill material.

3. The method according to claim 1, characterized in that, Based on the aforementioned joint material property database, a multi-scale mechanical model is constructed, including macroscopic structural models and microscopic interface models, comprising: Construct a macroscopic structural model; Constructing a microstructure model; The transition region between the macroscopic structural model and the microscopic structural model is established based on the Arlequin coupling algorithm to obtain the coupling model between the macroscopic structural model and the microscopic structural model. A material response surface proxy model is established based on the aforementioned coupling model to obtain the parameter transfer mechanism; The solution strategy is set based on the arc length control method; The output includes a multi-scale mechanical model comprising macroscopic structural models, microscopic structural models, coupling models, parameter transfer mechanisms, and solution strategies.

4. The method according to claim 3, characterized in that, Constructing a macroscopic structural model, including: The structure is a discrete concrete structure using 8-node hexahedral elements. The elastic modulus of the concrete structure material is retrieved from the material property database at the joint, and the spatial distribution of the elastic modulus of the concrete structure material is described using the Weibull distribution. Apply load boundary conditions to obtain the macroscopic structural model.

5. The method according to claim 3, characterized in that, Constructing a microstructure model includes: Establish a locally encrypted sub-model at the joints of the concrete structure; Zero-thickness interface elements are implanted at the contact surface of the filling material at the joint between concrete structures. The bilinear softening model parameters of the interface unit were initially calibrated using the bond strength and fracture toughness from the material property database of the joint.

6. The method according to claim 1, characterized in that, Based on the material property database of the joint and the multi-scale mechanical model, the interface constitutive relation is constructed, including: Based on the material property database of the joint and the multi-scale mechanical model, the improved Park-Paulino bilinear constitutive model is used as the basic framework, and a creep effect correction term is introduced to obtain a one-dimensional multi-mechanism coupled constitutive framework. The one-dimensional multi-mechanism coupling constitutive framework is extended to a three-dimensional multi-mechanism coupling constitutive framework; The humidity diffusion equation is used to modify the three-dimensional multi-mechanism coupling constitutive framework to obtain a three-dimensional multi-mechanism coupling constitutive framework with humidity coupling. An improved differential evolution algorithm is used to perform parameter inversion on a three-dimensional multi-mechanism coupled constitutive framework containing humidity coupling in order to obtain the interface constitutive relation.

7. The method according to claim 1, characterized in that, Based on the material property database at the joint, the multi-scale mechanical model, and the interface constitutive relation, the creep stress at the joint of the concrete structure is predicted, including: Based on the material property database of the joint, time discretization is performed to obtain the time step sequence and the basic parameters of strain decomposition for each step; Based on the time step sequence, the basic parameters of strain decomposition at each step, and the interface constitutive relation, the joint stress, slip, and strain energy density of the current step are obtained. Multi-scale stress transfer is performed based on the joint stress, the slip, and the strain energy density to obtain the stress tensor of the macroscopic structure. The joint micro-stress and macro-structure stress at the current time step are obtained based on the stress tensor of the macro-structure. The creep stress at the joint of a concrete structure is predicted based on the micro-stress and macro-structural stress at the current time step.

8. A system for predicting creep stress at joints in concrete structures, characterized in that, The system for predicting creep stress at concrete structure joints includes: The module for building a database of material properties at joints is used to test concrete structural materials and filling materials at concrete structural joints, and to build a database of material properties at joints based on the test data. A multi-scale mechanical model construction module is used to construct a multi-scale mechanical model, including a macroscopic structural model and a microscopic interface model, based on the material property database of the joint. The interface constitutive relation construction module is used to construct the interface constitutive relation based on the material property database of the joint and the multi-scale mechanical model. A creep stress prediction module for concrete structure joints is used to predict the creep stress at concrete structure joints based on the joint material property database, the multi-scale mechanical model, and the interface constitutive relation.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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