CN117669077A - Prediction method, prediction device, prediction equipment and prediction storage medium for stress relaxation rate of steel strand - Google Patents
Prediction method, prediction device, prediction equipment and prediction storage medium for stress relaxation rate of steel strand Download PDFInfo
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Abstract
The invention provides a method, a device, equipment and a storage medium for predicting stress relaxation rate of a steel strand. The method comprises the following steps: acquiring a plurality of stress relaxation rate data obtained by performing a stress relaxation test on the steel strand based on the reference length and the reference initial force; wherein the plurality of stress relaxation rate data comprises stress relaxation rates at a plurality of different moments; determining a reference stress relaxation model of the steel strand based on the plurality of stress relaxation rate data; determining a correction coefficient under the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force; and correcting the reference stress relaxation model based on the correction coefficient to obtain a target stress relaxation model of the steel strand so as to predict the stress relaxation rate of the steel strand under the target length and/or the target initial force. The invention can realize accurate prediction of the stress relaxation rate of the steel strand.
Description
Technical Field
The invention relates to the technical field of anchor cable prestress, in particular to a method, a device and equipment for predicting stress relaxation rate of a steel strand and a storage medium.
Background
The prestress anchor cable reinforcing technology has a plurality of advantages and is widely applied to the field of slope reinforcing engineering. The stress relaxation of the anchor cable steel strand is caused by the fact that plastic deformation is continuously increased and elastic deformation is correspondingly reduced under the condition that the anchoring force of the anchor cable is maintained unchanged at the temperature and under the condition that total strain is maintained, so that the stress is slowly reduced along with time. Therefore, the material belongs to the inherent property of the material, and the anchor cable prestress loss caused by the stress relaxation phenomenon of the steel strand is unavoidable.
At present, in order to master the influence rule of stress relaxation on the prestress loss of an anchor cable, a stress relaxation test is generally carried out on an anchor cable steel strand to be used in construction through an indoor test. In actual engineering, a steel strand with the length of 1-3 m is generally selected to carry out a stress relaxation test under the initial force of 60% -70% Fm, and the stress relaxation time course analysis and the prediction of the stress relaxation rate of 1000h are carried out according to the experimental result. However, even if the steel strands with the same parameters are not uniform in length and tension when the stress relaxation rate test is performed and when the steel strands are actually used, test data and actual data may not be uniform, so that the stress relaxation model is not accurate enough, and the stress relaxation rate of the steel strands is difficult to accurately predict.
Disclosure of Invention
The embodiment of the invention provides a method, a device, equipment and a storage medium for predicting the stress relaxation rate of a steel strand, which are used for solving the problem of accurately predicting the stress relaxation rate of the steel strand.
In a first aspect, an embodiment of the present invention provides a method for predicting a stress relaxation rate of a steel strand, including:
acquiring a plurality of stress relaxation rate data obtained by performing a stress relaxation test on the steel strand based on the reference length and the reference initial force; wherein the plurality of stress relaxation rate data comprises stress relaxation rates at a plurality of different moments;
determining a reference stress relaxation model of the steel strand based on the plurality of stress relaxation rate data;
determining a correction coefficient under the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force;
and correcting the reference stress relaxation model based on the correction coefficient to obtain a target stress relaxation model of the steel strand so as to predict the stress relaxation rate of the steel strand under the target length and/or the target initial force.
In one possible implementation, the reference stress relaxation model is:
R 1 (t)＝R(T)·10 k(t-T)
wherein R is 1 (T) represents the stress relaxation rate of the steel strand at the time T, the reference length and the reference initial force, T represents the slope conversion point, and k represents the slope of the straight line segment;
The target stress relaxation model is:
wherein R is 2 (t) represents the stress relaxation rate of the steel strand at time t, target length and/or target initial force, ψ R Represents the stress relaxation rate correction coefficient, ψ k Represents the slope correction coefficient, ψ T Representing the slope transition point correction coefficient.
In one possible implementation, determining a reference stress relaxation model of the steel strand based on the stress relaxation rate data includes:
determining a slope conversion point of a reference stress relaxation model of the steel strand based on slope changes of fitted curves of the plurality of stress relaxation rate data;
correcting the reference stress relaxation model based on the correction coefficient includes:
correcting the slope conversion point of the reference stress relaxation model based on the slope conversion point correction coefficient to obtain a correction moment point;
and taking the corrected moment point as a slope conversion point of the target stress relaxation model.
In one possible implementation, determining the slope transition point of the reference stress relaxation model based on the slope change of the fitted curve of the plurality of stress relaxation rate data comprises:
sequencing stress relaxation rates at a plurality of different moments according to the sequence of the moments;
for each moment, performing linear fitting on each stress relaxation rate before the moment to obtain a first fitting equation, performing linear fitting on each stress relaxation rate after the moment to obtain a second fitting equation, and calculating the ratio of the slopes of the first fitting equation and the second fitting equation to serve as the slope ratio corresponding to the moment;
And determining the moment with the minimum corresponding slope ratio as a slope conversion point of the reference stress relaxation model.
In one possible implementation, determining the slope conversion point correction factor at the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force comprises:
calculation formulaObtaining a slope conversion point correction coefficient under the target length and/or the target initial force;
wherein, psi is T Representing the slope transition point correction coefficient, ζ L Represents the ratio of the target length to the reference length, ζ F Representing the target initial force and the reference initial force.
In one possible implementation, determining the stress relaxation rate correction factor at the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force comprises:
calculation formulaObtaining a stress relaxation rate correction coefficient under a target length and/or a target initial force;
wherein, psi is R Representing the stress relaxation rate correction coefficient, ζ L Represents the ratio of the target length to the reference length, ζ F Representing the target initial force and the reference initial force.
In one possible implementation, determining the slope correction factor at the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force comprises:
Calculation formula psi k ＝1.5ξ F -0.5, obtaining a slope correction factor at a target length and/or a target initial force;
wherein, psi is k Representing the slope correction coefficient, ζ F Representing the target initial force and the reference initial force.
In a second aspect, an embodiment of the present invention provides a device for predicting a stress relaxation rate of a steel strand, including:
the acquisition module is used for acquiring a plurality of stress relaxation rate data obtained by performing a stress relaxation test on the steel strand based on the reference length and the reference initial force; wherein the plurality of stress relaxation rate data comprises stress relaxation rates at a plurality of different moments;
the reference model construction module is used for determining a reference stress relaxation model of the steel strand based on the stress relaxation rate data;
the correction coefficient determining module is used for determining a correction coefficient under the target length and/or the target initial force based on the ratio of the target length to the reference length, and/or the ratio of the target initial force to the reference initial force;
the model correction module is used for correcting the reference stress relaxation model based on the correction coefficient to obtain a target stress relaxation model of the steel strand so as to predict the stress relaxation rate of the steel strand under the target length and/or the target initial force.
In a third aspect, an embodiment of the present invention provides an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of the method according to the first aspect or any one of the possible implementations of the first aspect, when the computer program is executed by the processor.
In a fourth aspect, embodiments of the present invention provide a computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of the method as described above in the first aspect or any one of the possible implementations of the first aspect.
The embodiment of the invention provides a prediction method, a device, equipment and a storage medium for stress relaxation rate of a steel strand, wherein a correction coefficient is determined by utilizing the relation between the stress relaxation rate of the steel strand and the length and initial force applied to the steel strand, a stress relaxation model of the steel strand under a reference length and a reference initial force is corrected into a stress relaxation model of the steel strand under a target length and/or a target initial force, so that the accurate prediction for the stress relaxation rate of the steel strand is realized, and the stress relaxation models of the steel strand under different lengths and/or initial forces are not required to be respectively constructed through experiments.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flowchart of a method for predicting a stress relaxation rate of a steel strand according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a vertical electro-hydraulic servo universal tester provided by an embodiment of the present invention;
FIG. 3 is a schematic diagram of a horizontal electro-hydraulic servo universal tester provided by an embodiment of the invention;
FIG. 4 is a schematic diagram of a static stress-strain test analysis system according to an embodiment of the present invention;
FIG. 5 is a graph of load versus elongation for a tip of a steel strand test specimen provided in accordance with an embodiment of the present invention;
fig. 6 is a graph of steel strand spool force versus time for an initial force=0.4 Fm condition provided by an embodiment of the present invention;
fig. 7 is a graph of "axial force versus time" for a steel strand under an initial force=0.6fm condition provided by an embodiment of the present invention;
Fig. 8 is a graph of "axial force versus time" for a steel strand under an initial force=0.8fm condition provided by an embodiment of the present invention;
fig. 9 is a graph of "lgR-t" for a steel strand under an initial force=0.4fm condition provided by an embodiment of the present invention;
fig. 10 is a graph of "lgR-t" for a steel strand under an initial force=0.6fm condition provided by an embodiment of the present invention;
fig. 11 is a graph of "lgR-t" for a steel strand under an initial force=0.8fm condition provided by an embodiment of the present invention;
FIG. 12 is a schematic diagram of determining a slope transition point according to an embodiment of the present invention;
FIG. 13 is a schematic structural diagram of a device for predicting stress relaxation rate of steel strands according to an embodiment of the present invention;
fig. 14 is a schematic diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the following description will be made by way of specific embodiments with reference to the accompanying drawings.
The prestress anchor cable reinforcing technology has a plurality of advantages and is widely applied to the field of slope reinforcing engineering. The stress relaxation of the anchor cable steel strand is caused by the fact that plastic deformation is continuously increased and elastic deformation is correspondingly reduced under the condition that the anchoring force of the anchor cable is maintained unchanged at the temperature and under the condition that total strain is maintained, so that the stress is slowly reduced along with time. Therefore, the material belongs to the inherent property of the material, and the anchor cable prestress loss caused by the stress relaxation phenomenon of the steel strand is unavoidable. The anchor cable prestress loss comprises an instant loss and a time loss, and the scheme is used for analyzing the anchor cable prestress time loss. The time loss of the anchoring system mainly comprises the creep of the rock mass of the anchoring section, the damage creep of grouting materials, the creep of an external anchor pier and the stress relaxation of a steel strand. The stress relaxation of the anchor cable steel strand is caused by the fact that plastic deformation is continuously increased and elastic deformation is correspondingly reduced under the condition that the anchoring force of the anchor cable is kept unchanged at the temperature and under the condition that total strain is maintained, so that the stress is slowly reduced along with time. Therefore, the material belongs to the inherent property of the material, and the anchor cable prestress loss caused by the stress relaxation phenomenon of the steel strand is unavoidable.
In order to grasp the rule of influence of stress relaxation on the prestress loss of the anchor cable, the stress relaxation test is required to be carried out on the anchor cable steel strand to be used in construction in advance through an indoor test. The national standard GB T21839-2019 'method for testing steel for prestressed concrete' provides relevant regulations for the relaxation test of steel strands under the equal temperature condition, the test pattern is required to be kept for a certain length at a given temperature (usually 20 DEG), the change of force on the test pattern is started from the initial force, and the stress relaxation rates at different moments are calculated. The national standard describes the initial force of the relaxation test, namely the initial force is a certain percentage of the breaking force (Fm) of the steel strand, the recommended value is 70% Fm, and the length of the steel strand pattern is described, namely the required length is not less than 200m, preferably 1000mm or an integral multiple of the twisting distance of the steel strand. In actual engineering, a steel strand with the length of 1-3 m is generally selected to carry out a stress relaxation test under the initial force of 60% -70% Fm, and the stress relaxation time course analysis and the prediction of the stress relaxation rate of 1000h are carried out according to the experimental result.
In summary, the current specification does not provide rigid regulations on the initial force and the steel strand pattern length of the steel strand stress relaxation test, so that the system researches the stress relaxation rules of steel strands with different lengths under different initial force conditions, establishes an anchor cable steel strand stress relaxation time course model considering the steel strand length and the initial force to predict the steel strand stress relaxation rate under different lengths and the initial force conditions, and provides guidance for reasonable design and construction of the prestressed anchor cable.
Referring to fig. 1, a flowchart of an implementation of a method for predicting a stress relaxation rate of a steel strand according to an embodiment of the present invention is shown, and details are as follows:
step 101, obtaining a plurality of stress relaxation rate data obtained by performing a stress relaxation test on a steel strand based on a reference length and a reference initial force; wherein the plurality of stress relaxation rate data comprises stress relaxation rates at a plurality of different moments.
In this embodiment, an electrohydraulic servo universal tester may be specifically used to perform isothermal stress relaxation tests of three different initial force conditions (0.4 Fm, 0.6Fm, and 0.8 Fm) on four steel strand samples with different lengths (1 m, 3m, 5m, and 9 m), and for each test condition, the stress relaxation rate of the steel strand at each moment is recorded to form a plurality of stress relaxation rate data.
This test was performed using two types of equipment: (1) The vertical electrohydraulic servo universal tester shown in figure 2 can implement whole-course control and record stress relaxation data at the end of a 1-3 m long anchor cable; (2) The horizontal electrohydraulic servo universal tester shown in figure 3 can implement whole-course control and record stress relaxation data at the end of 5-9 m long anchor cable. In addition, the test is also provided with a static stress-strain test analysis system, as shown in fig. 4, which is used for assisting in measuring the change condition of the stress in the middle of the anchor cable. If the data of the testing machine are available, the data measured by the original system of the testing machine are preferentially adopted, and the data measured by the instrument play a role in monitoring whether the test is carried out smoothly.
The structure of the steel strand adopted in the test is 1 multiplied by 7, the nominal diameter is 15.20mm, and the nominal strength level is 1860MPa. The lengths of the selected steel strands are respectively 1m, 3m, 5m and 9m, and each length is respectively 3 steel strand samples, and the total number of the samples is 12. The factory breaking force of the batch of samples is 268-272 KN, and the average breaking force is 270KN. In order to check the breaking force of a test sample, 1 steel strand in the same batch is randomly selected from the samples used in the test, the steel strand samples are fixed on a tensile machine, the tensile force is applied until the steel strand breaks, and the tensile force value during breaking is recorded so as to design initial tensile force during the subsequent stress relaxation test. The "load-elongation" curve of the steel strand end is shown in fig. 5, and as can be seen from fig. 5, the breaking force is about 275KN, which is not much different from the factory data.
The test uses three different initial forces, namely 0.4Fm, 0.6Fm and 0.8Fm, and the corresponding initial forces are respectively 109.6kN, 162.8kN and 216.3kN. The four lengths of steel strands are respectively subjected to stress relaxation tests of the three initial forces. The steel strands with the lengths of 1m and 3m are tested on a vertical electrohydraulic servo universal tester, and the steel strands with the lengths of 5m and 9m are tested on the vertical electrohydraulic servo universal tester.
Before loading test, the sample and the strain gauge are required to be fixed, namely the steel strand sample is fixed on a testing machine, the steel strand sample is ensured to be correctly installed and aligned, a test clamp is used for clamping, so that the sample is ensured not to slide during loading and testing, and the strain gauge is adhered to the middle of the steel strand by using strong glue.
In the test process, prestressing force is applied at a uniform rate of 35kN/min according to a preset loading program, two ends of a sample are fixed after loading, and the force change condition of the steel strand shaft in the test period is recorded. Drawing an axial force-time curve of the steel strand according to the test data, and calculating the relaxation rate of each moment point to obtain a plurality of stress relaxation rate data of the steel strand under each test condition. The calculation formula of the relaxation rate is as follows:
wherein R (t) represents the relaxation rate at time t, F o The initial force is represented by F (t), and the internal force of the steel strand at time t is represented by F (t).
Step 102, determining a reference stress relaxation model of the steel strand based on the plurality of stress relaxation rate data.
In the present embodiment, based on a plurality of stress relaxation rate data, the stress relaxation law of the steel stranded wire at the reference length and the reference initial force can be summarized, thereby determining the reference stress relaxation model.
In the prior art, the reference stress relaxation model is used for predicting the stress relaxation rate of the same-model steel strand under any length and/or any initial force, but after the length and/or the initial force of the steel strand are changed, the stress relaxation rule is also changed, so that the predicted relaxation rate obtained based on the reference stress relaxation model is inaccurate.
Step 103, determining a correction coefficient under the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force.
In this embodiment, the stress relaxation characteristics of the steel strand are affected by the length and the initial force, so that when the length, the initial force, the length and the initial force are all changed, the ratio of the target value of the change amount to the reference value can be used to determine the correction coefficient, and the reference stress relaxation model is adjusted according to the specific change degree of the length and/or the initial force, so as to determine the stress relaxation characteristics of the steel strand under the target value of the change amount.
And 104, correcting the reference stress relaxation model based on the correction coefficient to obtain a target stress relaxation model of the steel strand so as to predict the stress relaxation rate of the steel strand under the target length and/or the target initial force.
In the embodiment of the invention, the correction coefficient is determined by utilizing the relation between the stress relaxation rate of the steel strand and the length and initial force applied to the steel strand, and the stress relaxation model of the steel strand under the reference length and the reference initial force is corrected to be the stress relaxation model of the steel strand under the target length and/or the target initial force, so that the accurate prediction of the stress relaxation rate of the steel strand is realized, and the stress relaxation models of the steel strand under different lengths and/or initial forces are not required to be respectively constructed through experiments.
In one possible implementation, the reference stress relaxation model is:
R 1 (t)＝R(T)·10 k(t-T)
wherein R is 1 (T) represents the stress relaxation rate of the steel strand at the time T, the reference length and the reference initial force, T represents the slope conversion point, and k represents the slope of the straight line segment;
the target stress relaxation model is:
wherein R is 2 (t) represents the stress relaxation rate of the steel strand at time t, target length and/or target initial force, ψ R Represents the stress relaxation rate correction coefficient, ψ k Represents the slope correction coefficient, ψ T Representing the slope transition point correction coefficient.
In this embodiment, FIGS. 6 to 8 show the values of 0.4F m 、0.6F m 、0.8F m The axial force-time curves of four steel strands with different lengths under three different initial forces are respectively 1m, 3m, 5m and 9m from top to bottom in the figure. As is clear from fig. 6 to 8, the internal force of the steel strand drops sharply in the first period of time and then gradually stabilizes at a certain point in time. From this, it is shown that the stress relaxation of the steel strand takes on the phenomena of fast and slow before slow, and shows a remarkable time-course effect. In addition, the longer the strand length, the greater the rate of the inner force sharply decreasing segment, the earlier the time to enter the slowly decaying segment, and at the same time, the smaller the inner force tending to stabilize the segment, under the same initial force. It can be seen that the more significant the stress relaxation phenomenon of the steel strand with increasing length, the more significant the length effect.
In order to further quantitatively analyze the stress relaxation law of the anchor cable, the relaxation rate of each curve is calculated according to the formula (1) in the data of fig. 6-8, and is plotted in a logarithmic coordinate system lgR-t to obtain the data of fig. 9-11, wherein the data are respectively 1m, 3m, 5m and 9m from bottom to top. As is clear from fig. 9 to 11, in the logarithmic coordinate system, lgR (t) develops linearly at a specific point in time after a curve of a certain period of time has elapsed, and therefore, it is appropriate to predict the long-term stress relaxation rate of the steel strand by using a linear segment equation in the logarithmic coordinate system.
Based on the characteristics of the curve, the long-term stress relaxation rate model of the steel strand can be expressed as follows:
lgR(t)＝lgR(T)+k(t-T) (2)
where R (T) represents the stress relaxation rate at time T, k represents the slope of the straight line segment, and T represents the time at which the curve segment is converted into the straight line segment.
Performing logarithmic transformation on the formula (2) to obtain an exponential form of the display expression of R (t):
R(t)＝R(T)·10 k(t-T) (3)
equation (3) is only a general expression of a long-term stress relaxation rate model of a steel strand, and can only predict the long-term stress relaxation rate of the steel strand according to stress relaxation test data under the conditions of a certain fixed length and a fixed initial force, but cannot predict the long-term stress relaxation rate under the conditions of other lengths and other initial forces. Therefore, it is necessary to further investigate the relationship between three parameters of T, R (T) and k, the length of the steel strand and the initial force, and to determine the target stress relaxation model by correcting the three parameters based on the correction coefficients, respectively.
In one possible implementation, determining a reference stress relaxation model of the steel strand based on the stress relaxation rate data includes:
determining a slope conversion point of a reference stress relaxation model of the steel strand based on slope changes of fitted curves of the plurality of stress relaxation rate data;
correcting the reference stress relaxation model based on the correction coefficient includes:
correcting the slope conversion point of the reference stress relaxation model based on the slope conversion point correction coefficient to obtain a correction moment point;
and taking the corrected moment point as a slope conversion point of the target stress relaxation model.
In this embodiment, to accurately establish a long-term stress relaxation time-course model of a steel strand, the following three key parameters need to be determined: (a) the time T at which the curve in the logarithmic coordinate system is converted into a straight line; (b) a relaxation rate R (T) from curve to straight line transition point; (c) slope k of straight line segment. The slope conversion point represents the conversion point of the curve segment and the straight line segment in the stress relaxation model, and after the slope conversion point of the reference stress relaxation model of the steel strand is determined based on the slope change of the fitting curve of the plurality of stress relaxation rate data, the slope conversion point of the reference stress relaxation model can be corrected to be used as the slope conversion point of the target stress relaxation model.
In one possible implementation, determining the slope transition point of the reference stress relaxation model based on the slope change of the fitted curve of the plurality of stress relaxation rate data comprises:
sequencing stress relaxation rates at a plurality of different moments according to the sequence of the moments;
for each moment, performing linear fitting on each stress relaxation rate before the moment to obtain a first fitting equation, performing linear fitting on each stress relaxation rate after the moment to obtain a second fitting equation, and calculating the ratio of the slopes of the first fitting equation and the second fitting equation to serve as the slope ratio corresponding to the moment;
and determining the moment with the minimum corresponding slope ratio as a slope conversion point of the reference stress relaxation model.
In this embodiment, a discrete point group slope variable point method is proposed to determine the above three parameters. As shown in fig. 12, there are n relaxation rate data points in the log coordinate system, let j=2, 3,..n-1, and the discrete individual relaxation rate data points are divided into two groups for each j: lgR (t) 1 ),lgR(t 2 ),...,lgR(t j-1 ) And lgR (t) j ),lgR(t j+1 ),...,lgR(t n ). Respectively performing linear fitting on the front data point and the rear data point by adopting a least square method to obtain the slopes of the front data fitting equation and the rear data fitting equation, and marking the slopes as F jf And F jb Slope ratio ψ j ＝F jb /F jf Taking psi j Minimum value corresponds toThe j-th time point of the curve is the time T for converting the curve into a straight line. At this time, the slope F of the linear fitting equation of the latter set of discrete data jb The slope k of the long-term stress relaxation time interval model is the intercept at the time t=t, i.e. lgR (T) of the curve to the straight line transition point.
Three key parameters of the stress relaxation rate model of each curve of fig. 9 to 12 can be obtained by using the method shown in fig. 12, and the results are shown in table 1. As can be seen from table 1, when the lengths of the strands are the same, T gradually decreases and R (T) gradually increases as the initial force increases; when the initial force is the same, T gradually decreases and R (T) gradually increases as the length increases. In addition, when the initial force is the same, k basically keeps unchanged and does not change along with the change of the length of the steel strand; as the strand length remains unchanged, k increases as the initial force increases.
TABLE 1
In one possible implementation, determining the slope conversion point correction factor at the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force comprises:
calculation formulaObtaining a slope conversion point correction coefficient under the target length and/or the target initial force;
Wherein, psi is T Representing the slope transition point correction coefficient, ζ L Represents the ratio of the target length to the reference length, ζ F Representing the target initial force and the reference initial force.
In this example, the length of the steel strand was 1.0m and the initial force was 0.6F m And the parameters T, R (T) and k obtained under the condition are used as references, and the parameters are multiplied by correction coefficients on the basis, so that the long-term stress relaxation equation parameters of the same type of steel stranded wire under the conditions of different lengths and different initial forces can be obtained. Therefore, each of Table 1The parameters are divided by the length of 1.0m and the initial force of 0.6F respectively m The corresponding T, R (T) and k (i.e., t=10.5, R (T) =0.0012, k=0.0008) resulted in the new data in table 2. In Table 2, xi L 、ξ F The ratio of the target length to the reference length, and the ratio of the target initial force to the reference initial force are respectively expressed.
TABLE 2
The calculation formula for the slope conversion point correction coefficient can be obtained by fitting the polynary nonlinear data according to the data in table 2 as follows:
when the length of the steel strand is unchanged, the calculation formula of the slope conversion point correction coefficient can be written as follows:
when the initial force of the steel strand is unchanged, the calculation formula of the slope conversion point correction coefficient can be written as follows:
in one possible implementation, determining the stress relaxation rate correction factor at the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force comprises:
Calculation formulaObtaining a stress relaxation rate correction coefficient under a target length and/or a target initial force;
wherein, psi is R Representing the stress relaxation rate correction coefficient, ζ L Represents the ratio of the target length to the reference length, ζ F Representing the target initial force and the reference initial force.
In this embodiment, the calculation formula for obtaining the stress relaxation rate correction coefficient is as follows, by performing the multi-element nonlinear data fitting according to the data in table 2:
when the length of the steel strand is unchanged, the calculation formula of the stress relaxation rate correction coefficient can be written as:
when the initial force of the steel strand is unchanged, the calculation formula of the stress relaxation rate correction coefficient can be written as:
in one possible implementation, determining the slope correction factor at the target length and/or the target initial force based on the ratio of the target length to the reference length and/or the ratio of the target initial force to the reference initial force comprises:
calculation formula psi k ＝1.5ξ F -0.5, obtaining a slope correction factor at a target length and/or a target initial force;
wherein, psi is k Representing the slope correction coefficient, ζ F Representing the target initial force and the reference initial force.
In this embodiment, the calculation formula for obtaining the slope correction coefficient is as follows:
ψ k ＝1.5ξ F -0.5
Substituting each correction coefficient into the formula (3) to obtain a general expression of the long-term stress relaxation model of the steel strand:
from the above, it is known that the long-term stress relaxation time course model of a steel strand is mainly controlled by three key parameters, namely T, R (T) and k. T decreases with increasing length of the steel strand and also decreases with increasing initial force; r (T) increases with the length of the steel strand and decreases with the initial force; k is not affected by the length of the steel strand and only increases with the initial force.
It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present invention.
The following are device embodiments of the invention, for details not described in detail therein, reference may be made to the corresponding method embodiments described above.
Fig. 13 is a schematic structural diagram of a device for predicting stress relaxation rate of a steel strand according to an embodiment of the present invention, and for convenience of explanation, only the portions relevant to the embodiment of the present invention are shown, and the details are as follows:
as shown in fig. 13, the apparatus 2 for predicting a stress relaxation rate of a steel strand includes:
An acquisition module 21 for acquiring a plurality of stress relaxation rate data obtained by performing a stress relaxation test on the steel strand based on the reference length and the reference initial force; wherein the plurality of stress relaxation rate data comprises stress relaxation rates at a plurality of different moments;
a reference model construction module 22 for determining a reference stress relaxation model of the steel strand based on the plurality of stress relaxation rate data;
a correction factor determining module 23, configured to determine a correction factor under the target length and/or the target initial force based on a ratio of the target length to the reference length, and/or a ratio of the target initial force to the reference initial force;
the model correction module 24 is configured to correct the reference stress relaxation model based on the correction coefficient, so as to obtain a target stress relaxation model of the steel strand, so as to predict a stress relaxation rate of the steel strand under a target length and/or a target initial force.
In one possible implementation, the reference stress relaxation model is:
R 1 (t)＝R(T)·10 k(t-T)
wherein R is 1 (T) represents the stress relaxation rate of the steel strand at the time T, the reference length and the reference initial force, T represents the slope conversion point, and k represents the slope of the straight line segment;
The target stress relaxation model is:
wherein R is 2 (t) represents the stress relaxation rate of the steel strand at time t, target length and/or target initial force, ψ R Represents the stress relaxation rate correction coefficient, ψ k Represents the slope correction coefficient, ψ T Representing the slope transition point correction coefficient.
In one possible implementation, the reference model building module 22 is specifically configured to:
determining a slope conversion point of a reference stress relaxation model of the steel strand based on slope changes of fitted curves of the plurality of stress relaxation rate data;
correcting the reference stress relaxation model based on the correction coefficient includes:
correcting the slope conversion point of the reference stress relaxation model based on the slope conversion point correction coefficient to obtain a correction moment point;
and taking the corrected moment point as a slope conversion point of the target stress relaxation model.
In one possible implementation, the reference model building module 22 is specifically configured to:
sequencing stress relaxation rates at a plurality of different moments according to the sequence of the moments;
for each moment, performing linear fitting on each stress relaxation rate before the moment to obtain a first fitting equation, performing linear fitting on each stress relaxation rate after the moment to obtain a second fitting equation, and calculating the ratio of the slopes of the first fitting equation and the second fitting equation to serve as the slope ratio corresponding to the moment;
And determining the moment with the minimum corresponding slope ratio as a slope conversion point of the reference stress relaxation model.
In one possible implementation, the correction factor determining module 23 is specifically configured to:
calculation formulaObtaining a slope conversion point correction coefficient under the target length and/or the target initial force;
wherein, psi is T Representing the slope transition point correction coefficient, ζ L Represents the ratio of the target length to the reference length, ζ F Representing the target initial force and the reference initial force.
In one possible implementation, the correction factor determining module 23 is specifically configured to:
calculation formulaObtaining a stress relaxation rate correction coefficient under a target length and/or a target initial force;
wherein, psi is R Representing the stress relaxation rate correction coefficient, ζ L Represents the ratio of the target length to the reference length, ζ F Representing the target initial force and the reference initial force.
In one possible implementation, the correction factor determining module 23 is specifically configured to:
calculation formula psi k ＝1.5ξ F -0.5Obtaining a slope correction coefficient under the target length and/or the target initial force;
wherein, psi is k Representing the slope correction coefficient, ζ F Representing the target initial force and the reference initial force.
According to the embodiment of the invention, the correction coefficient is determined by utilizing the relation between the stress relaxation rate of the steel strand and the length and initial force applied to the steel strand, and the stress relaxation model of the steel strand under the reference length and the reference initial force is corrected to be the stress relaxation model of the steel strand under the target length and/or the target initial force, so that the accurate prediction of the stress relaxation rate of the steel strand is realized, and the stress relaxation models of the steel strand under different lengths and/or initial forces are not required to be respectively constructed through experiments.
Fig. 14 is a schematic diagram of an electronic device according to an embodiment of the present invention. As shown in fig. 14, the electronic apparatus 5 of this embodiment includes: a processor 50, a memory 51 and a computer program 52 stored in said memory 51 and executable on said processor 50. The processor 50, when executing the computer program 52, performs the steps of the above-described embodiments of the method for predicting the stress relaxation rate of each steel strand, such as steps 101 to 104 shown in fig. 1. Alternatively, the processor 50 may perform the functions of the modules/units of the apparatus embodiments described above, such as the functions of the modules shown in fig. 13, when executing the computer program 52.
By way of example, the computer program 52 may be partitioned into one or more modules/units that are stored in the memory 51 and executed by the processor 50 to complete the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing the specified functions, which instruction segments are used to describe the execution of the computer program 52 in the electronic device 5. For example, the computer program 52 may be partitioned into the modules shown in fig. 13.
The electronic device 5 may be a computing device such as a desktop computer, a notebook computer, a palm computer, a cloud server, etc. The electronic device 5 may include, but is not limited to, a processor 50, a memory 51. It will be appreciated by those skilled in the art that fig. 14 is merely an example of the electronic device 5 and is not meant to be limiting as the electronic device 5 may include more or fewer components than shown, or may combine certain components, or different components, e.g., the electronic device may further include an input-output device, a network access device, a bus, etc.
The processor 50 may be a central processing unit (Central Processing Unit, CPU), other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field-programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 51 may be an internal storage unit of the electronic device 5, such as a hard disk or a memory of the electronic device 5. The memory 51 may be an external storage device of the electronic device 5, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card) or the like, which are provided on the electronic device 5. Further, the memory 51 may also include both an internal storage unit and an external storage device of the electronic device 5. The memory 51 is used for storing the computer program and other programs and data required by the electronic device. The memory 51 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/electronic device and method may be implemented in other manners. For example, the apparatus/electronic device embodiments described above are merely illustrative, e.g., the division of the modules or units is merely a logical function division, and there may be additional divisions in actual implementation, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated modules/units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present invention may implement all or part of the flow of the method of the above embodiment, or may be implemented by instructing the relevant hardware by a computer program, where the computer program may be stored in a computer readable storage medium, and the computer program may implement the steps of the method embodiment for predicting the stress relaxation rate of each steel strand when executed by a processor. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth. It should be noted that the computer readable medium may include content that is subject to appropriate increases and decreases as required by jurisdictions in which such content is subject to legislation and patent practice, such as in certain jurisdictions in which such content is not included as electrical carrier signals and telecommunication signals.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (10)
1. The method for predicting the stress relaxation rate of the steel strand is characterized by comprising the following steps of:
acquiring a plurality of stress relaxation rate data obtained by performing a stress relaxation test on the steel strand based on the reference length and the reference initial force; wherein the plurality of stress relaxation rate data comprises stress relaxation rates at a plurality of different moments;
determining a reference stress relaxation model of the steel strand based on the plurality of stress relaxation rate data;
determining a correction factor at a target length and/or a target initial force based on a ratio of the target length to the reference length and/or a ratio of a target initial force to the reference initial force;
And correcting the reference stress relaxation model based on the correction coefficient to obtain a target stress relaxation model of the steel strand so as to predict the stress relaxation rate of the steel strand under the target length and/or the target initial force.
2. The method for predicting the stress relaxation rate of a steel strand according to claim 1, wherein the reference stress relaxation model is:
R 1 (t)＝R(T)·10 k(t-T)
wherein R is 1 (T) represents the stress relaxation rate of the steel strand at the time T, the reference length and the reference initial force, T represents a slope conversion point, and k represents the slope of a straight line segment;
the target stress relaxation model is:
wherein R is 2 (t) represents the stress relaxation rate, ψ, of the steel strand at time t, the target length and/or the target initial force R Represents the stress relaxation rate correction coefficient, ψ k Represents the slope correction coefficient, ψ T Representing the slope transition point correction coefficient.
3. The method of predicting a stress relaxation rate of a steel strand according to claim 2, wherein the determining a reference stress relaxation model of the steel strand based on the stress relaxation rate data comprises:
determining a slope transition point of a reference stress relaxation model of the steel strand based on a slope change of a fitted curve of the plurality of stress relaxation rate data;
The modifying the reference stress relaxation model based on the correction factors includes:
correcting the slope conversion point of the reference stress relaxation model based on the slope conversion point correction coefficient to obtain a correction moment point;
and taking the corrected moment point as a slope conversion point of the target stress relaxation model.
4. A method of predicting a stress relaxation rate of a steel strand according to claim 3, wherein determining a slope transition point of the reference stress relaxation model based on a slope change of a fitted curve of the plurality of stress relaxation rate data comprises:
sequencing the stress relaxation rates at different moments according to the sequence of the moments;
for each moment, performing linear fitting on each stress relaxation rate before the moment to obtain a first fitting equation, performing linear fitting on each stress relaxation rate after the moment to obtain a second fitting equation, and calculating the ratio of the slopes of the first fitting equation and the second fitting equation to be used as the slope ratio corresponding to the moment;
and determining the moment with the minimum corresponding slope ratio as the slope conversion point of the reference stress relaxation model.
5. The method of predicting a stress relaxation rate of a steel strand according to claim 2, wherein determining a slope conversion point correction coefficient at a target length and/or a target initial force based on a ratio of the target length to the reference length and/or a ratio of the target initial force to the reference initial force comprises:
calculation formulaObtaining a slope conversion point correction coefficient under the target length and/or the target initial force;
wherein, psi is T Representing the slope transition point correction coefficient, ζ L Represents the ratio of the target length to the reference length, ζ F Representing the target initial force and the reference initial force.
6. The method of predicting a stress relaxation rate of a steel strand according to claim 2, wherein determining a stress relaxation rate correction factor at a target length and/or at the target initial force based on a ratio of the target length to the reference length and/or a ratio of a target initial force to the reference initial force comprises:
calculation formulaObtaining a stress relaxation rate correction coefficient under the target length and/or the target initial force;
wherein, psi is R Representing the stress relaxation rate correction coefficient, ζ L Represents the ratio of the target length to the reference length, ζ F Representing the target initial force and the reference initial force.
7. The method of predicting a stress relaxation rate of a steel strand according to claim 2, wherein determining a slope correction factor at a target length and/or at the target initial force based on a ratio of the target length to the reference length and/or a ratio of a target initial force to the reference initial force comprises:
calculation formula psi k ＝1.5ξ F -0.5, deriving a slope correction factor at said target length and/or said target initial force;
wherein, psi is k Representing the slope correction coefficient, ζ F Representing the target initial force and the reference initial force.
8. The predicting device for the stress relaxation rate of the steel strand is characterized by comprising:
the acquisition module is used for acquiring a plurality of stress relaxation rate data obtained by performing a stress relaxation test on the steel strand based on the reference length and the reference initial force; wherein the plurality of stress relaxation rate data comprises stress relaxation rates at a plurality of different moments;
a reference model building module for determining a reference stress relaxation model of the steel strand based on the plurality of stress relaxation rate data;
the correction coefficient determining module is used for determining a correction coefficient under the target length and/or the target initial force based on the ratio of the target length to the reference length, and/or the ratio of the target initial force to the reference initial force;
And the model correction module is used for correcting the reference stress relaxation model based on the correction coefficient to obtain a target stress relaxation model of the steel strand so as to predict the stress relaxation rate of the steel strand under the target length and/or the target initial force.
9. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of the preceding claims 1 to 7 when the computer program is executed.
10. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the method according to any of the preceding claims 1 to 7.
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