Full-life-cycle stress monitoring method for concrete elasticity modulus age relevance

Abstract

The invention discloses a full-life-cycle stress monitoring method for concrete elasticity modulus age relevance. The method comprises the following steps: providing a plurality of monitoring modules; when concrete is poured, the multiple monitoring modules are built in a concrete bin; a concrete equivalent age fitting model is established, and based on the concrete equivalent age fitting model, elastic moduli Es of different ages of the whole life cycle of the concrete are obtained; establishing a correlation formula of the elastic modulus Es of the concrete at different ages in the whole life cycle and the first comprehensive elastic modulus E1 and the second comprehensive elastic modulus E2, and obtaining coefficients a and b corresponding to the different ages in the whole life cycle of the concrete; and calculating the concrete stress delta c of the age based on the coefficients a and b corresponding to different ages, the first stress value delta 1 and the second stress value delta 2. According to the invention, real stress monitoring of the concrete in the whole life period from pouring to complete hardening can be realized.

Description

Technical Field

[0001] The present invention relates to the field of concrete stress monitoring, and in particular to a full life cycle stress monitoring method taking into account the age correlation of concrete elastic modulus. Background Art

[0002] During the process from pouring to hardening, concrete undergoes complex chemical reactions, and its form changes from liquid to solid and further hardens. The most prominent manifestation of the continuous development of age is the increase in elastic modulus and strength. According to the stress monitoring principle and load sharing principle, the deformation law of concrete during hardening can be well monitored and recorded according to strain. However, due to the continuous change of elastic modulus, stress monitoring is greatly affected, that is, the elastic modulus of concrete at an early age is too small, while the elastic modulus of concrete at an early and late stage is too large. At present, it is impossible to achieve stress monitoring of the same measurement point throughout its life cycle.

[0003] Although based on the above problems, some studies have proposed high-rigidity stress monitoring devices that can minimize the errors caused by changes in the elastic modulus, the result is that the numerical stress monitoring results of concrete at an early age are almost "0", and it is impossible to achieve numerical stress monitoring of the entire process from liquid to solid concrete. Summary of the invention

[0004] The purpose of the present invention is to provide a full life cycle stress monitoring method taking into account the age correlation of the elastic modulus of concrete, aiming to solve the stress monitoring problem of concrete from pouring to complete hardening throughout its life cycle.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A full life cycle stress monitoring method for concrete elastic modulus age correlation, the method comprising:

[0007] A plurality of monitoring modules are provided; wherein the monitoring modules include a first isolation tube and a second isolation tube, the first isolation tube and the second isolation tube are connected in parallel; a first tension and pressure sensor is provided in the first isolation tube along its axial direction, and a second tension and pressure sensor is provided in the second isolation tube along its axial direction; the first tension and pressure stress sensor has a first comprehensive elastic modulus E1, and the second tension and pressure stress sensor has a second comprehensive elastic modulus E2;

[0008] When pouring concrete, the plurality of monitoring modules are built in the concrete bin at the same time;

[0009] Establish a concrete equivalent age fitting model and obtain the elastic modulus E of concrete at different ages throughout its life cycle based on the concrete equivalent age fitting model. s ;

[0010] The correlation formula between the elastic modulus Es of concrete at different ages throughout its life cycle and the first comprehensive elastic modulus E1 and the second comprehensive elastic modulus E2 is established as follows:

[0011]

[0012] Based on the correlation formula, coefficients a and b corresponding to different ages of the entire life cycle of concrete are obtained;

[0013] Take out one of the monitoring modules at different ages during the whole life of concrete, and read the first stress value δ1 of the first tension and pressure sensor and the second stress value δ2 of the second tension and pressure sensor of the corresponding monitoring module;

[0014] Based on the coefficients a and b corresponding to the age and the first stress value δ1 and the second stress value δ2, according to the formula δ c =aδ1+bδ2, calculate the concrete stress δ at this age c .

[0015] Preferably, the first comprehensive elastic modulus E1 is much smaller than the second comprehensive elastic modulus E2.

[0016] Preferably, the first comprehensive elastic modulus E1 is less than 500 MPa, and the first comprehensive elastic modulus E1 is greater than 30 GPa.

[0017] Preferably, the method further comprises:

[0018] The concrete stress δ is calculated by the following method: c To make corrections:

[0019]

[0020] Among them, E c (τ) is the theoretical elastic modulus of concrete, m is the length ratio of the first tension and pressure sensor to the first isolation tube, and is the corrected concrete stress.

[0021] Preferably, the E s As shown below:

[0022]

[0023] Among them, τ is the age of concrete, E0 is the initial elastic modulus of concrete, E c is the final elastic modulus of concrete, and α and β are the preset coefficients of variation of concrete elastic modulus.

[0024] Preferably, the concrete equivalent age fitting model is:

[0025]

[0026] Where, τ is the age of concrete, E / R = 4000~5000K; T R is the preset reference temperature; T(τ) is the temperature of the concrete at time τ.

[0027] The advantages of the present invention are:

[0028] The whole life stress monitoring method of concrete elastic modulus age correlation provided by the present invention can realize the real stress monitoring of concrete in all stages from minimum hardening stiffness to maximum hardening completion stiffness. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the main steps of a full life cycle stress monitoring method of concrete elastic modulus age correlation according to the present invention;

[0030] Figure 2 It is a structural schematic diagram of a first isolation cylinder and a first tension and pressure sensor of the present invention;

[0031] Figure 3 It is a structural schematic diagram of a hoop lock of the present invention;

[0032] Figure 4 It is a schematic diagram of a state in which a plurality of monitoring modules are dispersedly cast in a concrete bin according to the present invention;

[0033] Figure 5 The present invention is a schematic diagram of a stress monitoring curve of concrete during its entire life cycle according to an embodiment. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0035] See attached Figure 1 , which are the main steps of a full life cycle stress monitoring method for the correlation between the elastic modulus of concrete and the age. The present embodiment provides a full life cycle stress monitoring method for the correlation between the elastic modulus of concrete and the age, including:

[0036] Step S1: provide multiple monitoring modules.

[0037] Specifically, the monitoring module 4 includes a first isolation tube 1 and a second isolation tube, which are connected in parallel through a clamp 2; a first tension and pressure sensor 3 is arranged in the first isolation tube 1 along its axial direction, and a second tension and pressure sensor is arranged in the second isolation tube along its axial direction. Figure 2 and Figure 3 , is a schematic diagram of the structure of the first isolation tube 1 and the first tension and pressure sensor 3, Figure 3Schematic diagram of the structure of the hoop lock. That is, select a certain length of isolation tube and a tension pressure sensor, clamp the tension pressure sensor in the isolation tube, and make the force measuring direction of the tension pressure sensor coaxial with the isolation tube. Connecting the first isolation tube 1 and the second isolation tube in parallel through the hoop lock 3 can ensure that the two tension pressure sensors detect the stress value of the same area.

[0038] The first tensile and compressive stress sensor has a first comprehensive elastic modulus E1, and the second tensile and compressive stress sensor has a second comprehensive elastic modulus E2. It should be noted that the comprehensive elastic modulus of the tensile and compressive stress sensor is an inherent property, and this parameter can be measured in the laboratory. For example, the tensile and compressive stress sensor uses a spoke sensor, and the force-bearing accessory of the spoke sensor is a sensitive beam. The comprehensive elastic modulus of the sensitive beam is measured to obtain the comprehensive elastic modulus of the tensile and compressive stress sensor.

[0039] This embodiment uses a sensor with two different comprehensive elastic moduli, wherein the first comprehensive elastic modulus E1 is much smaller than the second comprehensive elastic modulus E2. Preferably, the first comprehensive elastic modulus E1 is less than 500 MPa, and the first comprehensive elastic modulus E2 is greater than 30 GPa. In this way, the stress of the concrete over its entire life cycle can be calculated based on the principle of load sharing using the two comprehensive elastic moduli.

[0040] Step S2: When pouring concrete, multiple monitoring modules are built in the concrete bin.

[0041] See attached Figure 4 After the monitoring modules 4 are prepared, multiple monitoring modules 4 are dispersedly poured in the concrete bin during the pouring stage. It should be noted that during the burying process, large aggregates in the isolation cylinder need to be manually removed to prevent the large aggregates from filling the isolation cylinder.

[0042] Step S3: Establish a concrete equivalent age fitting model and obtain the elastic modulus E of concrete at different ages throughout its life cycle based on the concrete equivalent age fitting model. s .

[0043] Specifically, the concrete equivalent age fitting formula proposed by Academician Zhu Bofang (such as formula (1)) is used as the concrete equivalent age fitting model:

[0044]

[0045] Where, τ is the age of concrete, E / R = 4000~5000K; T R is the preset reference temperature; T(τ) is the temperature of the concrete at time τ.

[0046] Elastic modulus E of concrete at different ages throughout its life cycle s , as shown in formula (2):

[0047]

[0048] Among them, τ is the age of concrete, E0 is the initial elastic modulus of concrete, E c is the final elastic modulus of concrete, α and β are the preset coefficients of variation of concrete elastic modulus, and α and β are both constants.

[0049] Step S4: Establish the elastic modulus E of concrete at different ages throughout its life cycle according to formula (3): s The correlation formula with the first comprehensive elastic modulus E1 and the second comprehensive elastic modulus E2 is shown in formula (3).

[0050]

[0051] Step S5: Obtain coefficients a and b corresponding to different ages of the entire life cycle of concrete based on the correlation formula. That is, through formula (3), the coefficients a and b values ​​corresponding to different stages in the entire life cycle of concrete can be calculated.

[0052] Step S6: taking out a monitoring module at different ages during the whole life cycle of concrete, and reading the first stress value δ1 of the first tension and pressure sensor and the second stress value δ2 of the second tension and pressure sensor of the corresponding monitoring module.

[0053] Step S7: Based on the coefficients a and b corresponding to the age and the first stress value δ1 and the second stress value δ2, according to formula (4): δ c =aδ1+bδ2, calculate the concrete stress δ at this age c .

[0054] In addition, this embodiment can also calculate the concrete stress δ by the method shown in the following formula (5): c To make corrections:

[0055]

[0056] Among them, E c (τ) is the theoretical elastic modulus of concrete, m is the length ratio of the first tension and pressure sensor to the first isolation tube, δ′ c is the corrected concrete stress.

[0057] In addition, the embodiment of the present invention can also perform simulation inversion according to the different working conditions set by the above-mentioned field experiment, compare and analyze the corresponding stress calculation results, and perform repeated corrections according to formula (4) and formula (5) to clarify the respective monitoring stress value verification analysis models under temperature load conditions, autogenous shrinkage conditions, and external load conditions. The comprehensive verification formula is:

[0058]

[0059] Where: A c is the concrete stress area, A s is the stress area of ​​the tensile and compressive stress sensor, l s is the length of the isolation tube, l c is the axial length of the tensile and compressive stress sensor, and C is the creep coefficient of concrete.

[0060] See attached Figure 5 The concrete stress monitoring change curve and simulation analysis curve are monitored by the above method. The whole life stress monitoring method of concrete elastic modulus age correlation provided by the present invention can realize the real stress monitoring of concrete in all stages from the minimum hardening stiffness to the maximum hardening completion stiffness.

[0061] The above are preferred embodiments of the present invention and the technical principles used therein. For those skilled in the art, any obvious changes such as equivalent transformations, simple replacements, etc. based on the technical solution of the present invention, without departing from the spirit and scope of the present invention, are within the scope of protection of the present invention.

Claims

1. A full life cycle stress monitoring method for the correlation between concrete elastic modulus and age, characterized in that: The method comprises: A plurality of monitoring modules are provided; wherein the monitoring modules include a first isolation tube and a second isolation tube, the first isolation tube and the second isolation tube are connected in parallel; a first tension and pressure sensor is provided in the first isolation tube along its axial direction, and a second tension and pressure sensor is provided in the second isolation tube along its axial direction; the first tension and pressure stress sensor has a first comprehensive elastic modulus E1, and the second tension and pressure stress sensor has a second comprehensive elastic modulus E2; When pouring concrete, the plurality of monitoring modules are built in the concrete bin at the same time; Establish a concrete equivalent age fitting model and obtain the elastic modulus E of concrete at different ages throughout its life cycle based on the concrete equivalent age fitting model. s ; The correlation formula between the elastic modulus Es of concrete at different ages throughout its life cycle and the first comprehensive elastic modulus E1 and the second comprehensive elastic modulus E2 is established as follows: Based on the correlation formula, coefficients a and b corresponding to different ages of the entire life cycle of concrete are obtained; Take out one of the monitoring modules at different ages during the whole life of concrete, and read the first stress value δ1 of the first tension and pressure sensor and the second stress value δ2 of the second tension and pressure sensor of the corresponding monitoring module; Based on the coefficients a and b corresponding to the age and the first stress value δ1 and the second stress value δ2, according to the formula δ c =aδ1+bδ2, calculate the concrete stress δ at this age c .

2. The method for monitoring stress of concrete elastic modulus age correlation throughout its life cycle according to claim 1, characterized in that: The first comprehensive elastic modulus E1 is much smaller than the second comprehensive elastic modulus E2.

3. The method for monitoring stress of concrete elastic modulus age correlation throughout its life cycle as claimed in claim 2, characterized in that: The first comprehensive elastic modulus E1 is less than 500 MPa, and the first comprehensive elastic modulus E1 is greater than 30 GPa.

4. The method for monitoring stress of concrete elastic modulus age correlation throughout its life cycle according to claim 1, characterized in that: The method further comprises: The concrete stress δ is calculated by the following method: c To make corrections: Among them, E c (τ) is the theoretical elastic modulus of concrete, m is the length ratio of the first tension and pressure sensor to the first isolation tube, δ c ' is the corrected concrete stress.

5. The method for monitoring stress of concrete elastic modulus age correlation throughout its life cycle as claimed in claim 4, characterized in that: The E s As shown below: Among them, τ is the age of concrete, E0 is the initial elastic modulus of concrete, Ec is the final elastic modulus of concrete, and α and β are the preset coefficients of variation of concrete elastic modulus.

6. The method for monitoring stress of concrete elastic modulus age correlation throughout its life cycle as claimed in claim 5, characterized in that: The concrete equivalent age fitting model is: Where, τ is the age of concrete, E / R = 4000~5000K; T R is the preset reference temperature; T(τ) is the temperature of the concrete at time τ.

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