Method for testing time-varying Poisson's ratio of concrete

Abstract

The invention discloses a concrete time-varying Poisson's ratio testing method. The method comprises the following steps: placing concrete in a preset concrete creep measuring device; after multi-axial pressure is applied to the concrete, creep data of the concrete in the pressed direction, stress data and strain data of the concrete in other directions and concrete test parameters are obtained; calculating a creep coefficient corresponding to the concrete based on the concrete test parameters; calculating the time-varying elastic modulus of the concrete in the multi-axis state based on the creep coefficient and the creep data; and calculating the time-varying Poisson's ratio corresponding to the concrete based on the time-varying elastic modulus, the creep data, the stress data and the strain data. According to the improved concrete creep measurement device and method, the Poisson's ratio of the concrete in the multi-axis stress state can be more accurately tested, the precision of the test result is improved, a research method about the change of the Poisson's ratio of the concrete along with time under the multi-axis stress is provided, and the application prospect is wide. Therefore, the safety and durability of the concrete structure are effectively guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of material testing, and in particular to a method for testing the time-varying Poisson's ratio of concrete. Background Art

[0002] In today's construction field, concrete is a widely used structural material, and the stability and reliability of its performance are crucial to structural safety. However, in practical applications, concrete structures are often subjected to various loads for a long time, including cyclic loads such as traffic loads and earthquake loads, which cause slow and continuous changes in the microstructure inside the concrete material. This change not only affects the mechanical properties of concrete, but also causes irreversible deformation of the material, namely creep. The existence of creep will have a profound impact on the stability and safety of the structure, especially during long-term service. In addition, Poisson's ratio, as an important parameter describing the relationship between the volume change and the lateral size change of a material under stress, is of great significance for accurately predicting and simulating the response of the structure. Traditionally, Poisson's ratio is considered to be a fixed constant, but under the influence of long-term continuous loading, especially when considering the creep effect, Poisson's ratio will change significantly over time. This phenomenon is called time-varying Poisson's ratio. The measurement and calculation of time-varying Poisson's ratio is crucial for evaluating the deformation behavior of concrete structures under long-term and cyclic loads.

[0003] Although the creep behavior of concrete has been studied to a certain extent in existing research and practice, the law of the change of concrete Poisson's ratio over time under multi-axial loading conditions is still a technical problem. This time-varying Poisson's ratio under multi-axial loading has a profound impact on structural design and performance evaluation, but there is currently a lack of effective testing methods to accurately evaluate the deformation behavior of structures under long-term and cyclic loads, which affects the safety and durability of structures.

[0004] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Summary of the invention

[0005] The embodiment of the present application provides a method for testing the time-varying Poisson's ratio of concrete, which can more accurately test the Poisson's ratio of concrete under a multi-axial stress state, thereby improving the accuracy of the test results.

[0006] In order to solve the above technical problems, the present application provides a method for testing the time-varying Poisson's ratio of concrete, comprising:

[0007] Place the concrete in a preset concrete creep measurement device;

[0008] After applying pressure to the concrete, creep data and concrete test parameters corresponding to the concrete in the creep axis direction are obtained, and stress data and strain data on the remaining axes except the creep axis are obtained;

[0009] Calculate the creep coefficient corresponding to the concrete based on the concrete test parameters;

[0010] Calculating the time-varying elastic modulus of the concrete under a multiaxial state based on the creep coefficient and the creep data;

[0011] The time-varying Poisson's ratio corresponding to the concrete is calculated based on the time-varying elastic modulus, the creep data, the stress data and the strain data.

[0012] Furthermore, in some embodiments of the present application, the preset concrete creep measurement device includes a cavity, at least one pressure creep measuring device, at least one pressure reaction device and a steel ring, wherein the pressure creep measuring device is movably connected to the top cover or the body, the pressure reaction device is fixed on the body, and the stiffness of the steel ring meets the preset stiffness and is used to perform multi-directional constraints on the concrete.

[0013] Further, in some embodiments of the present application, the step of obtaining creep data and concrete test parameters corresponding to the concrete in the creep axis direction, and obtaining stress data and strain data on the remaining axes except the creep axis, includes:

[0014] The electro-hydraulic servo actuator is used to drive the pressure block to apply multi-axis pressure to the concrete;

[0015] The creep data of the concrete is collected by a linear variable differential transformer, and the creep data includes stress data and strain data in each axial direction of the concrete.

[0016] Furthermore, in some embodiments of the present application, the electro-hydraulic servo actuator is fixed on the pressure block, one end of the electro-hydraulic servo actuator is connected to the pressure block, and is used to drive the pressure block away from or close to the concrete; the pressure block is arranged in the inner cavity of the concrete creep measuring device, and is used to apply pressure to the concrete; the linear variable differential transformer is fixed on the top cover or the body and connected to the pressure block, and the linear variable differential transformer is used to measure the displacement change between the pressure block and the concrete to collect the creep data of the concrete.

[0017] Further, in some embodiments of the present application, the step of calculating the creep coefficient corresponding to the concrete based on the concrete test parameters includes:

[0018] Determine the concrete axial compressive strength value, environmental relative humidity, component thickness and aging coefficient based on the concrete parameters;

[0019] The creep coefficient corresponding to the concrete is calculated using a preset creep coefficient calculation formula according to the concrete axial compressive strength value, the environmental relative humidity, the component thickness and the aging coefficient.

[0020] Further, in some embodiments of the present application, the calculating the time-varying elastic modulus of the concrete under a multiaxial state based on the creep coefficient and the creep data includes:

[0021] determining an initial elastic modulus of the concrete at an initial moment;

[0022] The effective modulus method adjusted with age is adopted to calculate the time-varying elastic modulus of the concrete in each axial direction based on the initial elastic modulus, the creep coefficient and the creep data.

[0023] Further, in some embodiments of the present application, the calculating the time-varying Poisson's ratio corresponding to the concrete based on the time-varying elastic modulus, the creep data, the stress data and the strain data includes:

[0024] Based on the creep data, determining stress data and strain data of the concrete in each axial direction;

[0025] The time-varying Poisson's ratio of the concrete in each axial direction is calculated based on the time-varying elastic modulus, the stress data and the strain data.

[0026] Furthermore, in some embodiments of the present application, it also includes:

[0027] Acquire the creep data and concrete test parameters for a preset period of time to construct a creep coefficient data set;

[0028] The creep coefficient variation curve corresponding to the concrete is drawn based on the creep coefficient data set by data processing software.

[0029] Furthermore, in some embodiments of the present application, it also includes:

[0030] Acquire the time-varying elastic modulus and its corresponding time point within a preset time period, and construct a time-varying elastic modulus data set;

[0031] Based on the time-varying elastic modulus data set, a time-varying elastic modulus change curve corresponding to the concrete is drawn by data processing software.

[0032] Furthermore, in some embodiments of the present application, it also includes:

[0033] Analyzing the time-varying elastic modulus variation curve to obtain an analysis result;

[0034] The deformation behavior of the concrete under long-term load is predicted based on the analysis results to obtain a deformation prediction result.

[0035] The present application also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program as described in the steps of the above method.

[0036] The present application also provides a readable storage medium, wherein the storage medium stores a computer program, and the computer program implements the method described above when the computer program is executed by a processor.

[0037] The present application provides a method for testing the time-varying Poisson's ratio of concrete, comprising: placing concrete in a preset concrete creep measurement device; after applying pressure to the concrete, obtaining creep data and concrete test parameters corresponding to the concrete in the direction of the creep axis, and obtaining stress data and strain data on the remaining axes except the creep axis; calculating the creep coefficient corresponding to the concrete based on the concrete test parameters; calculating the time-varying elastic modulus of the concrete under a multi-axial state based on the creep coefficient and the creep data; calculating the time-varying Poisson's ratio corresponding to the concrete based on the time-varying elastic modulus, creep data, stress data and strain data. The concrete time-varying Poisson's ratio test scheme provided by the present application can more accurately evaluate the time-varying Poisson's ratio of concrete under a multi-axial stress state, thereby improving the accuracy of evaluating the long-term performance of concrete, and by more accurately predicting and simulating the deformation behavior of the structure under long-term and periodic loads, it helps to improve the safety and durability of the structure, fills the research gap on the law of the change of the Poisson's ratio of concrete over time under multi-axial stress, and provides a new research perspective for the long-term behavior of concrete materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 It is an application environment diagram of the time-varying Poisson's ratio test method for concrete provided in an embodiment of the present application;

[0040] Figure 2 It is a flow chart of a method for testing the time-varying Poisson's ratio of concrete provided in an embodiment of the present application;

[0041] Figure 3 It is a structural schematic diagram of a concrete time-varying Poisson's ratio testing device provided in an embodiment of the present application;

[0042] Figure 4 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of systems and methods consistent with the examples detailed in the attached claims, or with some aspects of the present application.

[0044] It should be noted that, in this article, the terms "include", "comprises" or any other variants thereof are intended to cover descriptions such as non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element. In addition, components, features, and elements with the same name in different embodiments of the present application may have the same meaning or different meanings, and their specific meanings need to be determined by their explanation in the specific embodiment or further combined with the context of the specific embodiment.

[0045] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0046] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present application, and have no specific meanings. Therefore, "module", "component" or "unit" can be used in a mixed manner.

[0047] During the use of concrete structures, long-term stress and cyclic loads (such as traffic loads, earthquake loads, etc.) will cause changes in the internal microstructure of concrete materials, resulting in changes in its mechanical properties. Creep refers to the irreversible deformation of materials that gradually occurs over time under continuous loading or constant stress. This deformation is not limited to the elastic and plastic stages, but also involves the continuous deformation of materials under long-term stress, which has a profound impact on the stability and safety of the structure.

[0048] At the same time, the Poisson's ratio of concrete is an important parameter that describes the relationship between the volume change and the lateral size change of a material when it is subjected to stress. In general, the Poisson's ratio is considered to be a constant, but after a material is loaded for a long time, especially when the creep effect is taken into account, the Poisson's ratio will change significantly. This phenomenon is called the time-varying Poisson's ratio. Measuring the creep of concrete and calculating the time-varying Poisson's ratio are essential for evaluating the deformation behavior of structures under long-term and cyclic loads. These data can help engineers predict and simulate the response of structures more accurately, thereby improving the safety and durability of structures.

[0049] In order to solve the above technical problems, the embodiment of the present application provides a time-varying Poisson's ratio test method for concrete, which provides an effective test method to accurately evaluate the deformation behavior of the structure under long-term and cyclic loads, and helps to improve the safety and durability of the structure.

[0050] Figure 1 FIG. 1 is an application environment diagram of a method for testing the time-varying Poisson's ratio of concrete in an embodiment. Figure 1 , the concrete time-varying Poisson's ratio test method is applied to the concrete time-varying Poisson's ratio test system. The concrete time-varying Poisson's ratio test system includes a terminal 110 and a server 120. The terminal 110 and the server 120 are connected through a network, and the terminal 110 can be a desktop terminal or a mobile terminal, and the mobile terminal can be at least one of a mobile phone, a tablet computer, a laptop computer, etc. The server 120 can be implemented by an independent server or a server cluster composed of multiple servers. The terminal 110 is used to place the concrete in a preset concrete creep measurement device; after applying pressure to the concrete, the creep data and concrete test parameters corresponding to the concrete in the creep axis direction are obtained, and the stress data and strain data on the remaining axes except the creep axis are obtained; the creep coefficient corresponding to the concrete is calculated based on the concrete test parameters; based on the creep coefficient and the creep data, the time-varying elastic modulus of the concrete under the multi-axial state is calculated; based on the time-varying elastic modulus, the creep data, the stress data and the strain data, the time-varying Poisson's ratio corresponding to the concrete is calculated.

[0051] See also Figure 2 , Figure 2 1 is a flow chart of a method for testing the time-varying Poisson's ratio of concrete provided in an embodiment of the present application. This embodiment mainly uses the application of the method for testing the time-varying Poisson's ratio of concrete to a concrete creep measurement device as an example to illustrate. The method for testing the time-varying Poisson's ratio of concrete provided in an embodiment of the present application includes the following steps:

[0052] S1. Place the concrete in a preset concrete creep measurement device;

[0053] Specifically, for step S1, the concrete sample is placed in a special concrete creep measurement device, which includes a cavity for accommodating the concrete sample and allowing pressure to be applied to the sample from multiple directions.

[0054] S2. After applying pressure to the concrete, obtain the creep data and concrete test parameters corresponding to the creep axis direction of the concrete, and obtain the stress data and strain data on the remaining axes except the creep axis;

[0055] Specifically, for step S2, multi-axis pressure is applied to the concrete by an electro-hydraulic servo actuator. The electro-hydraulic servo actuator is fixed on a pressure block, which is located in a cavity and is used to apply pressure to the concrete. A linear variable differential transformer (LVDT) is used to collect stress data and strain data of the concrete in each axial direction. Stress data and strain data can be collected in real time through strain gauges, reflecting the creep behavior of concrete under multi-axis stress. This embodiment obtains the corresponding creep data in a uniaxial (creep axis) direction, and then adds stress-strain gauges on the collars of the other two axes (except the creep axis), thereby subsequently calculating the Poisson's ratio in the other two directions by obtaining the stress-strain of the other two axes.

[0056] S3. Calculate the creep coefficient of the concrete based on the concrete test parameters;

[0057] Specifically, for step S3, a specific formula is used to calculate the creep coefficient according to the axial compressive strength value of the concrete, the relative humidity of the environment, the thickness of the component and the aging coefficient. The creep coefficient is used to describe the deformation capacity of the concrete under continuous stress over time.

[0058] S4. Calculate the time-varying elastic modulus of concrete under multiaxial conditions based on the creep coefficient and creep data;

[0059] Specifically, for step S4, the elastic modulus of the concrete at the initial moment is determined, and then the effective modulus method adjusted with age is used to calculate the time-varying elastic modulus of the concrete in each axial direction by combining the initial elastic modulus, creep coefficient and creep data.

[0060] S5. Calculate the time-varying Poisson's ratio of concrete based on the time-varying elastic modulus, creep data, stress data and strain data;

[0061] Specifically, for step S5, based on the creep data, the stress data and strain data of the concrete in each axial direction are determined. The time-varying Poisson's ratio of the concrete in each axial direction is calculated by combining the time-varying elastic modulus, the stress data and the strain data.

[0062] It can be seen that the concrete time-varying Poisson's ratio test method provided in this embodiment can more accurately predict the deformation behavior of concrete under long-term and cyclic loads, thereby improving the safety and durability of structural design; it fills the research gap on the law of temporal variation of the Poisson's ratio of concrete under multi-axial stress, and provides a new perspective for the long-term performance evaluation of concrete materials; by accurately evaluating the time-varying Poisson's ratio of concrete, engineers can better predict and simulate the response of the structure, thereby improving the safety and durability of the structure.

[0063] Furthermore, in some embodiments, the preset concrete creep measurement device includes a cavity, at least one pressure creep measuring device, at least one pressure reaction device and a steel ring, wherein the pressure creep measuring device is movably connected to the top cover or the body, the pressure reaction device is fixed on the body, and the stiffness of the steel ring meets the preset stiffness and is used to perform multi-directional constraints on the concrete.

[0064] Specifically, Figure 3 As shown, the concrete creep measuring device provided in this embodiment includes a cavity for accommodating a concrete sample; at least one pressure creep measuring device for applying pressure and measuring the creep of concrete; at least one pressure reaction device for providing a reaction force to ensure the stability of the concrete sample during the stress process; and a steel ring, whose stiffness meets the preset requirements, for constraining the concrete sample in multiple directions to simulate the multi-axial stress state in actual use.

[0065] In a specific embodiment, a cavity is provided in the device, and a pressure creep measuring device and a pressure reaction force device are also provided in the cavity. One pressure creep measuring device is movably connected to the top cover, two pressure creep measuring devices are movably connected to the body, and the three pressure reaction force devices are all fixed on the body; the pressure creep measuring devices and the pressure reaction force devices are arranged in a one-to-one correspondence.

[0066] Furthermore, in some embodiments, an electro-hydraulic servo actuator is fixed on a pressure block, one end of the electro-hydraulic servo actuator is connected to the pressure block, and is used to drive the pressure block away from or close to the concrete; the pressure block is arranged in an inner cavity of the concrete creep measuring device, and is used to apply pressure to the concrete; a linear variable differential transformer is fixed on a top cover or a body and connected to the pressure block, and the linear variable differential transformer is used to measure the displacement change between the pressure block and the concrete to collect the creep data of the concrete.

[0067] Specifically, the pressure creep measuring device provided in this embodiment includes an electro-hydraulic servo actuator and a linear variable differential transformer (LVDT). The electro-hydraulic servo actuator is used to drive the pressure block to apply multi-axis pressure to the concrete; the linear variable differential transformer is used to collect creep data of the concrete under multi-axis stress, including stress data and strain data. The pressure block is located in the cavity of the device, connected to the electro-hydraulic servo actuator, and used to apply pressure to the concrete. The reaction plate is fixed to the body of the device, connected to the pressure reaction device, and used to maintain the stability of the position of the concrete sample.

[0068] In a specific embodiment, the pressure creep measuring device includes an electro-hydraulic servo actuator and a linear variable differential transformer, one end of the electro-hydraulic servo actuator is fixed on a pressure block, the pressure block is located in the cavity, the linear variable differential transformer is fixed on the top cover or the body, and the electro-hydraulic servo actuator drives the pressure block to move away from or close to the position where the concrete is located. The three pressure reaction devices all include a positioning rod fixed to the body, one end of the positioning rod is provided with a reaction plate, and the reaction plate is located in the cavity. Under this structure, after the concrete enters the cavity, it is first placed on the reaction plate connected to the bottom of the body, and then the electro-hydraulic servo actuator is started. The pressure block first cooperates with the reaction plate to fix the concrete and then applies pressure to the concrete 80. The linear variable differential transformer collects the creep data of the concrete under the multi-axis state in real time through the strain and stress sheets.

[0069] In summary, the concrete creep measuring device provided in this embodiment includes a body with a concrete inlet on the top and a cavity inside, a top cover detachably connected to the top of the body, and a plurality of creep measuring devices for measuring concrete creep are also provided in the cavity, each creep measuring device is movably connected to the top cover or the body, and each reaction force device is fixed on the body; at least one creep measuring device is also used to cooperate with the reaction force device to fix the position of the concrete to be measured; each creep measuring device is a pressure creep measuring device. When creep test is performed on concrete, only a pressure creep measuring device and a pressure reaction device are provided in the device. Concrete enters the cavity in the machine body from the concrete inlet. Since the reaction devices are all pressure reaction devices, the concrete can be placed on the reaction plate. After the concrete is placed, the top cover is fixed to the machine body. The electro-hydraulic servo actuator of the pressure creep measuring device is selected to start according to demand. The electro-hydraulic servo actuator drives the pressure block to move in the direction close to the concrete. Multiple pressure blocks apply pressure to the concrete from multiple directions. The reaction plate maintains the stability of the concrete position. The linear variable differential transformer fixed on the top cover or the machine body and in contact with the pressure block collects the pressure creep data of the concrete in real time through strain gauges until the pressure creep measurement is completed. A ring with greater rigidity is set in the other two axis directions to constrain the lateral deformation of the concrete, and stress and strain gauges are used to measure the strain and stress in the other two axis directions.

[0070] This embodiment uses a high-rigidity steel ring to constrain the concrete sample in multiple directions, which can more accurately simulate the multi-axial stress state in actual use, thereby improving the accuracy and reliability of the test results; using a combination of an electro-hydraulic servo actuator and a LVDT, pressure can be accurately applied and creep data of concrete, including stress and strain data, can be collected, providing rich information for subsequent analysis; the design of the device allows simulation of the multi-axial stress environment that concrete may encounter in actual structures, making the test results more valuable for practical applications; through the improved test method, engineers can obtain more accurate concrete time-varying Poisson's ratio data, thereby more scientifically considering the long-term performance of materials in structural design and improving the safety and durability of the structure.

[0071] Further, in some embodiments, the pressure creep measuring device includes an electro-hydraulic servo actuator and a linear variable differential transformer, and step S2 "obtaining creep data and concrete test parameters corresponding to the creep axis direction of concrete, and obtaining stress data and strain data on the remaining axes except the creep axis" may specifically include:

[0072] S21. Using an electro-hydraulic servo actuator to drive a pressure block to apply multi-axis pressure to the concrete;

[0073] S22. Collect the creep data of concrete through a linear variable differential transformer, where the creep data includes stress data and strain data in each axial direction of the concrete.

[0074] Specifically, for step S2, the pressure creep measuring device includes an electro-hydraulic servo actuator and a linear variable differential transformer. When the electro-hydraulic servo actuator is started, it drives the pressure block to apply pressure to the concrete. During this process, the position change of the pressure block is monitored and recorded in real time by the linear variable differential transformer. The data collected by the linear variable differential transformer include the displacement change of the pressure block. These changes directly reflect the deformation of the concrete sample after being subjected to force, that is, the creep behavior. The pressure data of the concrete under the multi-axis state applied by the device are recorded as s x ,s y ,s z Among them, s x ,s y ,s z are the stresses of concrete on the x, y and z axes respectively. The creep deformation data of concrete under multiaxial state collected are recorded as e x ,e y ,e z Among them, e x ,e y ,e z are the strains of concrete on the x, y and z axes respectively.

[0075] This embodiment can precisely control the pressure applied to concrete and accurately measure its deformation by using a combination of an electro-hydraulic servo actuator and a linear variable differential transformer, thereby improving the accuracy and reliability of the test results; the use of a linear variable differential transformer can collect the creep data of concrete under multi-axial stress in real time, including stress and strain data, providing rich information for subsequent analysis; and by simulating the multi-axial stress environment that concrete may encounter in actual structures, the test results have more practical application value.

[0076] Further, in some embodiments, step S3 “calculating the creep coefficient corresponding to the concrete based on the concrete test parameters” includes:

[0077] S31. Determine the concrete axial compressive strength value, environmental relative humidity, component thickness and aging coefficient based on concrete parameters;

[0078] S32. Use the preset creep coefficient calculation formula to calculate the creep coefficient of concrete according to the concrete axial compressive strength value, environmental relative humidity, component thickness and aging coefficient.

[0079] Specifically, for step S3, several key parameters of concrete are first determined, including axial compressive strength value, environmental relative humidity, component thickness and aging coefficient. Among them, the axial compressive strength value reflects the strength characteristics of concrete when subjected to axial compression; environmental relative humidity affects the material properties of concrete, especially in creep behavior; component thickness is a geometric parameter of the concrete sample, affecting its mechanical response; and the aging coefficient is a material constant used to describe the rate at which concrete ages over time.

[0080] Use the preset creep coefficient calculation formula and the above parameters to calculate the creep coefficient of concrete. The creep coefficient calculation formula is as follows:

[0081]

[0082] β H =1.5[1+(0.012R H ) 18 ]2h0+250≤1500;

[0083] Where: f cm is the axial compressive strength of concrete, R H is the relative humidity of the environment (%), and h0 is the thickness of the component.

[0084] The creep coefficient calculation formula involves a quantitative description of the deformation behavior of concrete materials under sustained stress, and the formula may combine material mechanics, concrete science and empirical data.

[0085] In actual operation, it is necessary to collect the specific values ​​of the above parameters, which can be done through experimental measurement, environmental monitoring and material testing. The collected data needs to be input into the creep coefficient calculation formula through appropriate data processing methods.

[0086] This embodiment comprehensively considers multiple key parameters of concrete, and the method can more accurately predict the creep behavior of concrete materials under long-term loads; an accurate creep coefficient is crucial to the reliability of structural design, especially when designing structures that need to consider long-term performance (such as dams, bridges, and high-rise buildings); understanding the creep coefficient of concrete can help material scientists and engineers optimize the mix ratio of concrete to obtain better long-term performance.

[0087] Further, in some embodiments, step S4 “calculating the time-varying elastic modulus of concrete under a multiaxial state based on the creep coefficient and creep data” may specifically include:

[0088] S41. Determine the initial elastic modulus of concrete at the initial time;

[0089] S42. The effective modulus method adjusted with age is used to calculate the time-varying elastic modulus of concrete in each axial direction based on the initial elastic modulus, creep coefficient and creep data.

[0090] Specifically, for step S4, before calculating the time-varying elastic modulus, it is first necessary to determine the elastic modulus of concrete at the initial moment. The initial elastic modulus is an index of the stiffness of concrete at the initial stage of loading and can be obtained through standard test methods. The effective modulus method adjusted with age is used to calculate the time-varying elastic modulus of concrete under multi-axial state. This method takes into account the creep effect of concrete and adjusts the initial elastic modulus to reflect the time-varying elastic properties of concrete under continuous loading. Combined with the creep coefficient and creep data (including stress data and strain data) of concrete, the time-varying elastic modulus of concrete in each axial direction is calculated. The creep coefficient is a comprehensive parameter that reflects the deformation capacity of concrete under continuous stress. Creep data provides stress and strain information of concrete in different directions and is the key input for calculating the time-varying elastic modulus.

[0091] Use a specific calculation formula, combined with the initial elastic modulus, creep coefficient and creep data, to calculate the time-varying elastic modulus of concrete in each axial direction. The calculation formula is as follows:

[0092]

[0093] Where: E x , E y , E zare the elastic modulus of concrete on the x, y and z axes respectively, E0 is the elastic modulus of concrete at the initial moment, φ is the creep coefficient of concrete, χ is the aging coefficient, and the European EC2 standard recommends a value of 0.55.

[0094] This embodiment comprehensively considers the initial elastic modulus, creep coefficient and creep data of concrete, and the method can more accurately predict the change of elastic modulus of concrete material under long-term load; accurate time-varying elastic modulus is crucial to the reliability of structural design, especially when designing structures that need to consider long-term performance (such as dams, bridges and high-rise buildings); understanding the time-varying elastic modulus of concrete can help material scientists and engineers optimize the mix ratio of concrete to obtain better long-term performance.

[0095] Further, in some embodiments, step S5 “calculating the time-varying Poisson's ratio corresponding to the concrete based on the time-varying elastic modulus, creep data, stress data and strain data” may specifically include:

[0096] S51. Based on the creep data, determine the stress data and strain data of the concrete in each axial direction;

[0097] S52. Based on the time-varying elastic modulus, stress data and strain data, calculate the time-varying Poisson's ratio of concrete in each axial direction.

[0098] Specifically, for step S5, determine the stress data and strain data

[0099] First, based on the creep data, determine the stress data of concrete in each axial direction (s x ,s y ,s z ) and strain data (e x ,e y ,e z ). These data are collected in real time by strain gauges installed on concrete samples, reflecting the deformation of concrete under multi-axial loads. Combined with the time-varying elastic modulus (E x , E y , E z ), stress data and strain data, calculate the time-varying Poisson's ratio of concrete in each axial direction (n x ,n y ,n z ). The time-varying Poisson's ratio refers to the change in the ratio of the lateral strain to the axial strain of concrete under continuous stress over time.

[0100] The time-varying Poisson's ratio of concrete in each axial direction is calculated using a specific calculation formula combined with the time-varying elastic modulus, stress data, and strain data. The calculation formula is as follows:

[0101]

[0102] Where: s x ,s y ,s z Stress data of concrete in each axial direction, e x ,e y ,e z is the strain data of concrete in each axial direction, E x , E y , E z is the time-varying elastic modulus of concrete in each axial direction, n x ,n y ,n z is the time-varying Poisson's ratio of concrete in each axial direction.

[0103] This embodiment comprehensively considers the time-varying elastic modulus, stress data and strain data of concrete, and the method can more accurately predict the change of Poisson's ratio of concrete materials under long-term loads; accurate time-varying Poisson's ratio is crucial to the reliability of structural design, especially when designing structures (such as dams, bridges and high-rise buildings) that need to consider material nonlinearity and long-term performance; understanding the time-varying Poisson's ratio of concrete can help material scientists and engineers optimize the mix ratio of concrete to obtain better long-term performance and durability.

[0104] Further, in some embodiments, the concrete time-varying Poisson's ratio testing method further includes:

[0105] S61. Obtain creep data and concrete test parameters for a preset period of time and construct a creep coefficient data set;

[0106] S62. Based on the creep coefficient data set, draw the creep coefficient variation curve corresponding to the concrete through data processing software.

[0107] Specifically, this embodiment also provides a method for calculating the creep coefficient change curve of concrete during the loading time, and the specific process is as follows: the creep data and related test parameters of concrete are continuously collected within a preset time period. The creep data includes stress and strain data of concrete in different axial directions, which reflect the deformation behavior of concrete under multi-axial stress state. The test parameters include environmental relative humidity, temperature, compressive strength of concrete, etc., which affect the creep behavior of concrete. Using the collected data, a creep coefficient data set is constructed. The creep coefficient data set contains creep coefficients at different time points, which are calculated by using specific calculation formulas, combined with the test parameters and creep data of concrete. Through data processing software, the creep coefficient change curve corresponding to the concrete is drawn based on the creep coefficient data set. These curves intuitively show the changing trend of the creep coefficient of concrete over time, and provide visual data for analyzing the long-term behavior of concrete.

[0108] This embodiment can more accurately predict the creep behavior of concrete materials under long-term loads by continuously collecting data and constructing a creep coefficient data set; an accurate creep coefficient variation curve is crucial to the reliability of structural design, especially when the design needs to consider the long-term performance of the material; understanding the variation trend of the creep coefficient of concrete over time can help engineers formulate more reasonable maintenance and repair plans to extend the service life of the structure; the creep coefficient data set and variation curve provide researchers with valuable data resources, which is helpful for in-depth research on the long-term behavior of concrete materials and promotes the research and development of new materials and new technologies.

[0109] Further, in some embodiments, the concrete time-varying Poisson's ratio testing method further includes:

[0110] S71. Obtaining the time-varying elastic modulus and its corresponding time point within a preset period of time, and constructing a time-varying elastic modulus data set;

[0111] S72. Based on the time-varying elastic modulus data set, draw a time-varying elastic modulus change curve corresponding to the concrete using data processing software.

[0112] Specifically, this embodiment also provides a method for calculating the time-varying elastic modulus change curve of concrete, and the specific process is as follows: continuously collect the time-varying elastic modulus data of concrete within a preset time period. The time-varying elastic modulus data reflects the change of the elastic modulus of concrete over time under continuous force. Using the collected time-varying elastic modulus data, a time-varying elastic modulus data set is constructed. This data set contains the time-varying elastic modulus values ​​at different time points, and these values ​​are obtained through a specific calculation method, combined with the creep data and test parameters of concrete. Through data processing software, the time-varying elastic modulus change curve corresponding to the concrete is drawn based on the time-varying elastic modulus data set. These curves intuitively show the changing trend of the time-varying elastic modulus of concrete over time, and provide visual data for analyzing the long-term behavior of concrete.

[0113] This embodiment can more accurately predict the change of elastic modulus of concrete materials under long-term loads by continuously collecting time-varying elastic modulus data and constructing a data set; an accurate time-varying elastic modulus change curve is crucial to the reliability of structural design, especially when designing structures that need to consider the long-term performance of materials; understanding the changing trend of the time-varying elastic modulus of concrete over time can help engineers formulate more reasonable maintenance and repair plans to extend the service life of the structure; the time-varying elastic modulus data set and change curve provide researchers with valuable data resources, which is helpful for in-depth research on the long-term behavior of concrete materials and promotes the research and development of new materials and new technologies.

[0114] Furthermore, in some embodiments, the concrete time-varying Poisson's ratio testing method further includes:

[0115] S81. Analyze the time-varying elastic modulus change curve to obtain analysis results;

[0116] S82. Based on the analysis results, the deformation behavior of concrete under long-term load is predicted to obtain deformation prediction results.

[0117] Specifically, this embodiment also provides a deformation prediction method, which uses a time-varying elastic modulus change curve drawn by data processing software to perform a detailed analysis. The analysis includes the identification of the trend, inflection point, change rate and other characteristics of the curve, as well as the relationship between these characteristics and the concrete material properties, environmental conditions and loading history. Based on the analysis results of the time-varying elastic modulus change curve, the deformation behavior of concrete under long-term load is predicted. By using mathematical models or machine learning methods, future behavior is estimated based on historical data and analysis results. Based on the prediction results, corresponding countermeasures are formulated, such as adjusting the structural design, formulating a maintenance plan or strengthening. These measures are intended to improve the safety and durability of the structure and reduce possible damage under long-term loads.

[0118] This embodiment can more accurately predict the deformation behavior of concrete materials under long-term loads by systematically analyzing the time-varying elastic modulus change curve; combined with the prediction results, designers can take into account the long-term behavior of the material in the design stage, thereby improving the foresight and adaptability of the structural design; accurate predictions can help engineers formulate more reasonable maintenance and overhaul plans to extend the service life of the structure and reduce maintenance costs; by predicting and responding to deformation behavior under long-term loads, the safety and durability of the structure can be significantly improved, and the risk of structural failure caused by material aging or fatigue can be reduced.

[0119] In summary, the concrete time-varying Poisson's ratio test method provided in this embodiment includes: placing concrete in a preset concrete creep measurement device; after applying pressure to the concrete, obtaining the creep data and concrete test parameters corresponding to the concrete in the creep axis direction, and obtaining the stress data and strain data on the remaining axes except the creep axis; calculating the creep coefficient corresponding to the concrete based on the concrete test parameters; calculating the time-varying elastic modulus of the concrete under a multi-axial state based on the creep coefficient and the creep data; and calculating the time-varying Poisson's ratio corresponding to the concrete based on the time-varying elastic modulus, the creep data, the stress data and the strain data. The concrete time-varying Poisson's ratio test scheme provided in this embodiment can more accurately evaluate the time-varying Poisson's ratio of concrete under a multi-axial stress state, thereby improving the accuracy of evaluating the long-term performance of concrete, and by more accurately predicting and simulating the deformation behavior of the structure under long-term and periodic loads, it helps to improve the safety and durability of the structure, fills the research gap on the law of the change of the Poisson's ratio of concrete over time under multi-axial stress, and provides a new research perspective for the long-term behavior of concrete materials.

[0120] It should be understood that although Figure 2 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 2 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed 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 part of the sub-steps or stages of other steps.

[0121] In addition, the present application also provides an electronic device, such as Figure 4 As shown, it shows a schematic diagram of the structure of the electronic device involved in the embodiment of the present application, specifically:

[0122] The electronic device may include components such as a processor 301 with one or more processing cores, a memory 302 with one or more computer-readable storage media, a power supply 303, and an input unit 304. Those skilled in the art will appreciate that Figure 4 The electronic device structure shown in the figure does not constitute a limitation on the electronic device, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0123] The processor 301 is the control center of the electronic device. It uses various interfaces and lines to connect various parts of the entire electronic device. By running or executing software programs and / or modules stored in the memory 302, and calling data stored in the memory 302, it executes various functions of the electronic device and processes data, thereby monitoring the electronic device as a whole. Optionally, the processor 301 may include one or more processing cores; preferably, the processor 301 may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface, and application programs, and the modem processor mainly processes wireless communications. It is understandable that the above-mentioned modem processor may not be integrated into the processor 301.

[0124] The memory 302 can be used to store software programs and modules. The processor 301 executes various functional applications and the concrete time-varying Poisson's ratio test method by running the software programs and modules stored in the memory 302. The memory 302 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the electronic device, etc. In addition, the memory 302 can include a high-speed random access memory, and can also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage devices. Accordingly, the memory 302 can also include a memory controller to provide the processor 301 with access to the memory 302.

[0125] The electronic device also includes a power supply 303 for supplying power to each component. Preferably, the power supply 303 can be logically connected to the processor 301 through a power management system, so that the power management system can manage charging, discharging, power consumption and other functions. The power supply 303 can also include one or more DC or AC power supplies, recharging systems, power failure detection circuits, power converters or inverters, power status indicators and other arbitrary components.

[0126] The electronic device may further include an input unit 304, which may be used to receive input digital or character information and generate keyboard, mouse, joystick, optical or trackball signal input related to user settings and function control.

[0127] Although not shown, the electronic device may further include a display unit, etc., which will not be described in detail herein. Specifically in this embodiment, the processor 301 in the electronic device will load the executable files corresponding to the processes of one or more application programs into the memory 302 according to the following instructions, and the processor 301 will run the application programs stored in the memory 302, thereby realizing various functions, as follows:

[0128] Place the concrete in a preset concrete creep measurement device; after applying pressure to the concrete, obtain the creep data and concrete test parameters corresponding to the concrete in the direction of the creep axis, and obtain the stress data and strain data on the remaining axes except the creep axis; calculate the creep coefficient corresponding to the concrete based on the concrete test parameters; calculate the time-varying elastic modulus of the concrete under the multi-axial state based on the creep coefficient and creep data; calculate the time-varying Poisson's ratio corresponding to the concrete based on the time-varying elastic modulus, creep data, stress data and strain data.

[0129] The specific implementation of the above operations can be found in the previous embodiments, which will not be described in detail here.

[0130] The embodiments of the present application can more accurately evaluate the time-varying Poisson's ratio of concrete under multi-axial stress, thereby improving the accuracy of evaluating the long-term performance of concrete. By more accurately predicting and simulating the deformation behavior of structures under long-term and cyclic loads, it helps to improve the safety and durability of structures, fills the research gap on the law of temporal variation of the Poisson's ratio of concrete under multi-axial stress, and provides a new research perspective for the long-term behavior of concrete materials.

[0131] A person of ordinary skill in the art will appreciate that all or part of the steps in the various methods of the above embodiments may be completed by instructions, or by controlling related hardware through instructions. The instructions may be stored in a computer-readable storage medium and loaded and executed by a processor.

[0132] To this end, an embodiment of the present application provides a storage medium in which a plurality of instructions are stored, and the instructions can be loaded by a processor to execute the steps in any concrete time-varying Poisson's ratio test provided in the embodiment of the present application. For example, the instructions can execute the following steps:

[0133] Place the concrete in a preset concrete creep measurement device; after applying pressure to the concrete, obtain the creep data and concrete test parameters corresponding to the concrete in the direction of the creep axis, and obtain the stress data and strain data on the remaining axes except the creep axis; calculate the creep coefficient corresponding to the concrete based on the concrete test parameters; calculate the time-varying elastic modulus of the concrete under the multi-axial state based on the creep coefficient and creep data; calculate the time-varying Poisson's ratio corresponding to the concrete based on the time-varying elastic modulus, creep data, stress data and strain data.

[0134] The specific implementation of the above operations can be found in the previous embodiments, which will not be described in detail here.

[0135] The storage medium may include: a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0136] Since the instructions stored in the storage medium can execute the steps in any one of the concrete time-varying Poisson's ratio test methods provided in the embodiments of the present application, the beneficial effects that can be achieved by any one of the concrete time-varying Poisson's ratio test methods provided in the embodiments of the present application can be achieved. For details, please refer to the previous embodiments and will not be repeated here.

[0137] The above is a detailed introduction to a method for testing the time-varying Poisson's ratio of concrete provided in an embodiment of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for testing time-varying Poisson's ratio of concrete, characterized in that: The steps include: Place the concrete in a preset concrete creep measurement device; After applying pressure to the concrete, creep data and concrete test parameters corresponding to the concrete in the creep axis direction are obtained, and stress data and strain data on the remaining axes except the creep axis are obtained; Calculate the creep coefficient corresponding to the concrete based on the concrete test parameters; Calculating the time-varying elastic modulus of the concrete under a multiaxial state based on the creep coefficient and the creep data; The time-varying Poisson's ratio corresponding to the concrete is calculated based on the time-varying elastic modulus, the creep data, the stress data and the strain data.

2. The method for testing the time-varying Poisson's ratio of concrete according to claim 1, characterized in that: The preset concrete creep measurement device includes a cavity, at least one pressure creep measuring device, at least one pressure reaction device and a steel ring, wherein the pressure creep measuring device is movably connected to the top cover or the body, the pressure reaction device is fixed on the body, and the stiffness of the steel ring meets the preset stiffness and is used to perform multi-directional constraints on the concrete.

3. The method for testing the time-varying Poisson's ratio of concrete according to claim 2, characterized in that: The step of obtaining creep data and concrete test parameters corresponding to the concrete in the creep axis direction, and obtaining stress data and strain data on the remaining axes except the creep axis, includes: The electro-hydraulic servo actuator is used to drive the pressure block to apply multi-axis pressure to the concrete; The creep data of the concrete is collected by a linear variable differential transformer, and the creep data includes stress data and strain data in each axial direction of the concrete.

4. The method for testing the time-varying Poisson's ratio of concrete according to claim 3, characterized in that: The electro-hydraulic servo actuator is fixed on the pressure block, and one end of the electro-hydraulic servo actuator is connected to the pressure block, so as to drive the pressure block to move away from or closer to the concrete; the pressure block is arranged in the inner cavity of the concrete creep measuring device, so as to apply pressure to the concrete; the linear variable differential transformer is fixed on the top cover or the body and connected to the pressure block, and the linear variable differential transformer is used to measure the displacement change between the pressure block and the concrete, so as to collect the creep data of the concrete.

5. The method for testing the time-varying Poisson's ratio of concrete according to claim 1, characterized in that: The calculating the creep coefficient corresponding to the concrete based on the concrete test parameters includes: Determine the concrete axial compressive strength value, environmental relative humidity, component thickness and aging coefficient based on the concrete parameters; The creep coefficient corresponding to the concrete is calculated using a preset creep coefficient calculation formula according to the concrete axial compressive strength value, the environmental relative humidity, the component thickness and the aging coefficient.

6. The method for testing the time-varying Poisson's ratio of concrete according to claim 1, characterized in that: The step of calculating the time-varying elastic modulus of the concrete under a multiaxial state based on the creep coefficient and the creep data comprises: determining an initial elastic modulus of the concrete at an initial moment; The effective modulus method adjusted with age is adopted to calculate the time-varying elastic modulus of the concrete in each axial direction based on the initial elastic modulus, the creep coefficient and the creep data.

7. The method for testing the time-varying Poisson's ratio of concrete according to claim 1, characterized in that: The calculating the time-varying Poisson's ratio corresponding to the concrete based on the time-varying elastic modulus, the creep data, the stress data and the strain data comprises: Based on the creep data, determining stress data and strain data of the concrete in each axial direction; The time-varying Poisson's ratio of the concrete in each axial direction is calculated based on the time-varying elastic modulus, the stress data and the strain data.

8. The method for testing the time-varying Poisson's ratio of concrete according to claim 1, characterized in that: Also includes: Acquire the creep data and concrete test parameters for a preset period of time to construct a creep coefficient data set; Based on the creep coefficient data set, a creep coefficient variation curve corresponding to the concrete is drawn by data processing software.

9. The method for testing the time-varying Poisson's ratio of concrete according to claim 1, characterized in that: Also includes: Acquire the time-varying elastic modulus and its corresponding time point within a preset time period, and construct a time-varying elastic modulus data set; Based on the time-varying elastic modulus data set, a time-varying elastic modulus change curve corresponding to the concrete is drawn by data processing software.

10. The method for testing the time-varying Poisson's ratio of concrete according to claim 9, characterized in that: Also includes: Analyzing the time-varying elastic modulus variation curve to obtain an analysis result; The deformation behavior of the concrete under long-term load is predicted based on the analysis results to obtain a deformation prediction result.

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