A numerical simulation method and system for the mechanical properties of grouting sleeve under repeated tensile and compressive stresses

Abstract

This invention discloses a numerical simulation method and system for the mechanical properties of grouting sleeves under repeated tension and compression, belonging to the field of data processing. The numerical simulation method includes the following steps: obtaining the basic parameters of the grouting sleeve connectors; solving for the reference mechanical parameters of the grouting sleeve based on the basic parameters; calculating the secant stiffness and stiffness degradation under repeated loading, and solving for the failure load, slip load, and equivalent mechanical parameters of the grouting material; calculating the axial and circumferential strain and stress of the reinforcing steel and the sleeve, as well as the reduced load under the interaction of multiple factors; determining the axial ultimate bearing capacity of the grouting sleeve and the corresponding main failure modes; plotting the force-displacement curve, hysteresis curve, and load-strain curve; performing compliance checks on the three curves, and outputting the structural safety factor and damage risk warning. The numerical simulation method of this invention improves the accuracy of numerical simulation under repeated tension and compression conditions and its universal adaptability across multiple material systems.

Description

Technical Field

[0001] This invention relates to the field of data processing, and in particular to a numerical simulation method and system for the mechanical properties of grouting sleeves under repeated tensile and compressive stress. Background Technology

[0002] Grouting sleeve connection is one of the most widely used steel reinforcement connection methods in prefabricated concrete structures. It achieves force transfer through the synergistic effect between the sleeve, grout, and steel reinforcement. Engineering practice shows that under the influence of seismic action, dynamic loads, and long-term cyclic loads, grouting sleeves often undergo repeated tension and compression processes, and their load-bearing capacity, ductility, and stiffness degradation characteristics are significantly affected.

[0003] The connection performance of grouting sleeves is not only related to the strength of the reinforcing steel and the sleeve structure, but also affected by factors such as the type of grout, interfacial bonding performance, degree of grouting defects, eccentricity of stress, and cyclic loading regime. When these parameters change, the failure mode and ultimate bearing capacity of the grouting sleeve often show significant differences.

[0004] Currently, engineering design and scientific research analysis still mainly rely on empirical formulas, standard lookup tables, and manual calculations to evaluate relevant indicators. While these methods can meet the needs of some simple working conditions, they suffer from problems such as cumbersome calculation processes, low efficiency, and susceptibility to human error. At the same time, most existing analysis tools focus on calculating single indicators and lack integrated functions such as parameter input, performance calculation, curve generation, standard verification, and result export.

[0005] Furthermore, most existing programs fail to adequately consider the performance differences between various grouting material systems, especially when applying materials such as ordinary grouting materials, ultra-high performance concrete, and fiber-reinforced concrete, making unified modeling and comparative analysis difficult. Therefore, developing a numerical analysis system that can accommodate multiple grouting materials, simulate the entire cyclic tensile and compressive process, and automatically identify failure modes has significant engineering application value and promotional implications. Summary of the Invention

[0006] This invention provides a numerical simulation method and system for the mechanical properties of grouting sleeves under repeated tensile and compressive stress. The method can calculate and analyze the stress behavior of grouting sleeves under cyclic loading based on actual engineering input conditions, and automatically output key performance indicators.

[0007] A first aspect of the present invention provides a numerical simulation method for the mechanical properties of a grouting sleeve under repeated tensile and compressive stress. The numerical simulation method includes the following steps:

[0008] S1. Obtain the basic parameters of the grouting sleeve connector according to the preset test and structural design requirements;

[0009] S2. Solve for the reference mechanical parameters of the grouting sleeve under uniaxial tension based on the basic parameters;

[0010] S3. Calculate the secant stiffness K of the grouting sleeve joint under repeated loading. c The study also addresses stiffness degradation and solves for mechanical parameters such as failure load, slip load, and grouting material of key components during cyclic loading.

[0011] S4. Based on the actual stress conditions of the grouting sleeve, calculate the axial and circumferential strains, stresses, and reduced loads under the interaction of multiple factors of the reinforcing steel and the sleeve.

[0012] S5. Summarize all types of ultimate loads and determine the axial ultimate bearing capacity of the grouting sleeve and the corresponding main failure modes;

[0013] S6. Plot the force-displacement curve, hysteresis curve, and load-strain curve; compare the three curves with the preset "Technical Specification for Mechanical Connection of Reinforcing Steel" for compliance check, output the structural safety factor and damage risk warning, and give the optimal grouting material selection suggestion based on the comparison of multiple material libraries, and finally generate a standardized numerical simulation calculation report.

[0014] Based on the aforementioned numerical simulation method for the mechanical properties of grouting sleeves under repeated tensile and compressive stresses, the basic parameters in S1 include: steel reinforcement grade, steel reinforcement diameter d, and sleeve outer diameter D. out Sleeve inner diameter D in Bonding length L s Anchorage length L e Grouting material type, grouting material compressive strength f cg , grouting material elastic modulus E g , Bond strength between steel reinforcement and grout grout-sleeve bond strength , Eccentricity of force e, Grouting defect rate ξ, Shear key height h, Number of shear keys n k The number of load cycles n and the type of test load;

[0015] The test loading types include high-stress repeated tension-compression test, large deformation repeated tension-compression test, and general repeated tension-compression test;

[0016] The grouting material types include ordinary grouting material, ultra-high performance concrete and fiber concrete. The system automatically matches and calls its exclusive constitutive relationship and interface mechanical parameters according to the selected grouting material type.

[0017] Furthermore, in step S2, the reference mechanical parameters include: the ductility ratio μ of the grouting sleeve and the ultimate tensile strength f of the grouting sleeve. u Ultimate tensile load P of steel reinforcement u Pull-out load P at the rebar-grout interface rgGrouting material-sleeve interface pull-out load P gs , Reinforcing steel yield load P y and sleeve yield load P sleeve The specific calculation methods for each reference mechanical parameter are as follows:

[0018] The calculation method for the ductility ratio μ of the grouting sleeve is as follows:

[0019] ;

[0020] In the formula, d is the diameter of the steel bar, in mm;

[0021] ultimate tensile strength f of grouting sleeve u The calculation method is as follows:

[0022] ;

[0023] In the formula, f is the ultimate tensile strength of the grouting sleeve. u The unit is MPa; f u0 η represents the reference tensile strength of the reinforcing steel, in MPa. d α is the influence coefficient of grouting defect length. d L is the grouting defect location coefficient; e The anchorage length is in mm; L d The length of the grouting defect is in mm.

[0024] Ultimate tensile load P of steel reinforcement u The calculation method is as follows:

[0025] ;

[0026] In the formula, A s This refers to the cross-sectional area of ​​the reinforcing bars, in mm². 2 Ultimate tensile load P of steel reinforcement u The unit is kN; d is the diameter of the steel bar, in mm;

[0027] Pull-out load P at the rebar-grout interface rg The calculation method is as follows:

[0028] ;

[0029] In the formula, P is the pull-out load at the steel bar-grout interface. rg The unit is kN; η r The interface reinforcement coefficient generated by the rib constraint of the steel reinforcement; The bond strength between the steel reinforcement and the grout is expressed in MPa.

[0030] Grouting material-sleeve interface pull-out load P gs The calculation method is as follows:

[0031] ;

[0032] In the formula, P is the pull-out load at the grout-sleeve interface. gs The unit is kN; η s D is the interfacial reinforcement coefficient resulting from the shear key on the inner wall of the sleeve and the surface roughness; in The inner diameter of the sleeve is in mm; The bonding strength between the grout and the sleeve is expressed in MPa.

[0033] Reinforcement yield load P y The calculation method is as follows:

[0034] ;

[0035] In the formula, the yield load of the steel reinforcement is P y The unit is kN; f y This refers to the yield strength of the steel reinforcement, expressed in MPa.

[0036] Sleeve yield load P sleeve The calculation method is as follows:

[0037] ;

[0038] In the formula, A st The cross-sectional area of ​​the sleeve is in mm². 2 Sleeve yield load P sleeve The unit is kN; f ys D represents the sleeve yield strength, in MPa. out The outer diameter of the sleeve is in mm.

[0039] Furthermore, in step S3, the mechanical parameters of key component failure load, slip load, and grouting material include: shear key shear failure load P. kv Shear key bearing ultimate load P kc Sleeve slip load P slip Equivalent stiffness K of grouting material g Effective bonding length L with grout eff ;

[0040] Secant stiffness K c The calculation method is as follows:

[0041] ;

[0042] In the formula, the secant stiffness K c The unit is kN / mm; h is the shear key height, in mm;

[0043] Shear failure load P of shear keykv The calculation method is as follows:

[0044] ;

[0045] In the formula, the shear failure load P of the shear key is... kv The unit is kN; A k This represents the total cross-sectional area of ​​the shear key, in mm². 2 ;D in f is the inner diameter of the sleeve, in mm; cg The compressive strength of the grout is expressed in MPa.

[0046] ultimate shear key bearing capacity P kc The calculation method is as follows:

[0047] ;

[0048] In the formula, P is the ultimate load of the shear key under bearing pressure. kc The unit is kN;

[0049] Equivalent stiffness K of grouting material g The calculation method is as follows:

[0050] ;

[0051] In the formula, K represents the equivalent stiffness of the grouting material. g The unit is kN / mm; A g The effective annular cross-sectional area of ​​the grouting material is expressed in mm². 2 E g This refers to the elastic modulus of the grout, expressed in MPa.

[0052] Effective bond length L of grout eff The calculation method is as follows:

[0053] ;

[0054] In the formula, L is the effective bonding length of the grout. eff The unit is mm;

[0055] Sleeve slip load P slip The calculation method is as follows:

[0056] ;

[0057] In the formula, the sleeve sliding load P slip The unit is kN; The allowable limit slip is expressed in mm.

[0058] Furthermore, in step S4, the circumferential strain, stress, and reduced load include: longitudinal strain ε of the reinforcing steel.l axial stress σ of steel bars s Circumferential strain ε of the sleeve h Circumferential equivalent stress σ of the sleeve t Eccentricity reduction load P ecc and grouting defect reduction load P def ;

[0059] Axial stress σ of steel bars s The calculation method is as follows:

[0060] ;

[0061] In the formula, the axial stress σ of the steel bar s The unit is MPa;

[0062] Circumferential equivalent stress σ of sleeve t The calculation method is as follows:

[0063] ;

[0064] In the formula, the circumferential equivalent stress σ of the sleeve t The unit is MPa;

[0065] Calculate the longitudinal strain ε of the steel reinforcement according to the test loading type. l :

[0066] ;

[0067] In the formula, ε l0 σ represents the initial longitudinal strain of the reinforcing bar. s denoted as axial stress of the reinforcing bar, in MPa; k1 and k2 are strain correction factors, respectively.

[0068] The circumferential strain ε of the sleeve is calculated according to the test loading type and zone. h :

[0069] ;

[0070] In the formula, ε h0 K represents the initial circumferential strain of the sleeve; k3 and k4 are strain correction coefficients, respectively.

[0071] Eccentricity reduction load P ecc and grouting defect reduction load P def The calculation method is as follows:

[0072] ;

[0073] In the formula, the eccentricity reduces the load P. ecc The unit is kN; grouting defect reduction load P def The unit is kN; Pbase P is the ultimate tensile load of the steel reinforcement. u Pull-out load P at the rebar-grout interface rg Grouting material-sleeve interface pull-out load P gs Sleeve yield load P sleeve Shear failure load P of shear key kv Shear key bearing ultimate load P kc Sleeve slip load P slip The minimum value in; pull-out load P at the rebar-grout interface rg Pull-out load P at the grout-sleeve interface gs Not participating in P base The value is set so that the reduction only applies to the uncorrected load, avoiding repeated reductions.

[0074] Furthermore, in step S5, the ultimate load includes: the ultimate tensile load P of the reinforcing steel. u Pull-out load P at the rebar-grout interface rg Grouting material-sleeve interface pull-out load P gs , Reinforcing steel yield load P y Sleeve yield load P sleeve Shear failure load P of shear key kv Shear key bearing ultimate load P kc Sleeve slip load P slip Eccentricity reduction load P ecc and grouting defect reduction load P def ;

[0075] When determining the axial ultimate bearing capacity, the steel reinforcement yield load P is removed. y The minimum value of the external ultimate load is taken as the axial ultimate bearing capacity of the grouting sleeve.

[0076] Furthermore, the hysteresis curve generation method in step S6 is as follows: cyclic calculation is performed according to the graded loading system of the high stress repeated tension and compression test and the large deformation repeated tension and compression test in the specification. At the same time, the stiffness degradation, curve pinching effect and interface slip effect in the cyclic process are considered, and the displacement and load correspondence is fitted one cycle at a time. The greater the stiffness of the grouting material, the weaker the pinching effect of the hysteresis curve, and the slower the stiffness degradation rate of the grouting sleeve connector.

[0077] A second aspect of the present invention provides a numerical simulation system for the repeated tensile and compressive mechanical properties of a grouting sleeve, used for performing the numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve according to the first aspect of the present invention. The numerical simulation system includes:

[0078] Parameter input module;

[0079] Multi-type grouting material parameter library module; The multi-type grouting material parameter library module has built-in standard values ​​for compressive strength, elastic modulus and interfacial bond strength of three types of materials: ordinary grouting materials, ultra-high performance concrete and fiber concrete;

[0080] Core calculation module; The core calculation module executes the numerical simulation method of the mechanical properties of the grouting sleeve under repeated tension and compression according to the first aspect of the present invention, and completes the calculation of mechanical properties by substituting different grouting material parameters.

[0081] Curve generation module; The curve generation module generates force-displacement curves, hysteresis curves, load-longitudinal strain curves, and load-circumferential strain curves based on the calculation results;

[0082] The results display module; and the report export module;

[0083] Furthermore, the numerical simulation system automatically matches the corresponding grouting material parameters, completes the comparison of the mechanical properties of the grouting sleeve under different working conditions, and provides suggestions for the selection of grouting material and optimization schemes for the sleeve structure.

[0084] Compared with the prior art, the present invention has the following beneficial effects:

[0085] The numerical simulation method of this invention does not rely on a specific single component or single material constitutive model, and realizes refined and systematic prediction of mechanical properties. It can effectively avoid the simulation distortion problem caused by neglecting the interaction of cyclic loading or material degradation in traditional simulations, and improve the accuracy of numerical simulation under repeated tension and compression conditions and the universal adaptability across multiple material systems. Attached Figure Description

[0086] Figure 1 A flowchart of the numerical simulation method for the mechanical properties of grouting sleeve under repeated tensile and compressive stress;

[0087] Figure 2 A schematic diagram showing the structural parameters of the sleeve and reinforcing bars in the grouting sleeve;

[0088] Figure 3 The force-displacement curve of the grouting sleeve;

[0089] Figure 4 The hysteresis curve of the grouting sleeve under repeated tension and compression. Detailed Implementation

[0090] To make the technical problem to be solved, the technical solution and advantages of the present invention clearer, the following description will be provided in conjunction with the accompanying drawings. Figures 1 to 4 The technical solution of the present invention will be clearly and completely described in conjunction with specific embodiments.

[0091] The flowchart of the numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve of the present invention is as follows: Figure 1As shown, numerical simulation methods can be used to simulate and calculate multiple types of grouting materials. These multiple types of grouting materials refer to three categories commonly used in engineering: ordinary grouting materials, ultra-high performance concrete (UHPC), and fiber-reinforced concrete. UHPC is a type of ultra-high performance concrete grouting material, while fiber-reinforced concrete is a type of grouting material incorporating fibers to improve toughness and crack resistance.

[0092] The grouting sleeve of this invention refers to an axially loaded connection unit formed by reinforcing bars, a sleeve, grouting material inside the sleeve, and shear keys on the inner wall of the sleeve. The shear keys are rib-shaped or key-shaped structures on the inner wall of the sleeve used for interlocking and force transmission with the grouting material. The structural parameters of the shear keys are: shear key height h and the number of shear keys n. k Grouting defect rate This is the proportion of areas with insufficient grout, voids, or loose compaction that are converted into the effective grouting area. Eccentricity of force. It is a dimensionless index representing the degree of deviation between the axis of the reinforcing bar and the axis of the sleeve. Secant stiffness It is the ratio of the peak load of a certain cycle of repeated tension and compression to the corresponding displacement; the interface pull-out load is the critical load that can be transmitted before the relative pull-out of the steel bar-grout interface or the grout-sleeve interface occurs. Effective bond length. It is the actual anchorage length obtained by back-calculation based on the interface force transmission capacity.

[0093] The numerical simulation system for the repeated tensile and compressive mechanical properties of grouting sleeves of this invention can be written in Python. The system includes a parameter input module, a multi-type grouting material parameter library module, a core calculation module, a curve generation module, a result display module, and a report export module. The parameter input module is used to input parameters such as rebar grade, diameter, sleeve size, grouting material type, grouting defect rate, stress eccentricity, shear key parameters, number of cycles, test type, and environmental data such as temperature, humidity, and curing days. It supports direct input of numbers and drop-down selection. The environmental data is used for working condition recording and report output and does not participate in the calculation of the core mechanical formulas of this invention. The multi-type grouting material parameter library module stores standard mechanical parameters for ordinary grouting materials, UHPC, and fiber-reinforced concrete, including compressive strength, elastic modulus, rebar-grouting material bond strength, and grouting material-sleeve bond strength. These parameters are automatically retrieved after material selection, or can be modified according to actual conditions. The core calculation module includes the Grout Sleeve Calculator program, which contains all the calculation formulas of this invention and can automatically calculate the ductility ratio μ and the ultimate tensile strength f of the grouting sleeve. u Ultimate tensile load P of steel reinforcement u Secant stiffness K cThe calculations include shear key bearing capacity, equivalent stress stiffness of grout, effective bond length, bearing capacity and strain of grout sleeve connectors. The curve generation module uses Matplotlib to plot force-displacement curves, repeated tension-compression hysteresis curves, load-longitudinal strain curves, and load-circumferential strain curves based on the calculation results, taking into account stiffness degradation, pinching effect, and interface slip. The results display module shows the calculated indicators, comparison results with the "Technical Specification for Mechanical Connections of Reinforcing Steel Bars," failure modes, risk warnings, and optimization suggestions. The report export module can export the calculation results as a TXT text file or an Excel spreadsheet.

[0094] The numerical simulation method of this invention does not rely on a specific single component or single material constitutive model, and realizes refined and systematic prediction of mechanical properties. It can effectively avoid the simulation distortion problem caused by neglecting the interaction of cyclic loading or material degradation in traditional simulations, and improve the accuracy of numerical simulation under repeated tension and compression conditions and the universal adaptability across multiple material systems.

[0095] The following provides a specific embodiment to illustrate the numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve of the present invention.

[0096] Figure 2 This is a schematic diagram showing the structural parameters of the sleeve and reinforcing steel in a grouting sleeve. HRB400 grade reinforcing steel, commonly used in engineering, is selected, with a steel diameter d = 20 mm and a sleeve inner diameter D. in =40mm, sleeve outer diameter D out =50mm, anchorage length L e =160mm, bonding length L s =300mm; Number of shear keys n k =8 shear keys, shear key height h=3.0mm; grouting defect rate ξ=0, force eccentricity e=0, number of cyclic loading n=20, the test conditions adopt the high stress repeated tension and compression test specified in the "Technical Specification for Mechanical Connection of Reinforcing Steel", ambient temperature 20℃, humidity 60%, curing days 28d. Ordinary grouting material is used for calculation.

[0097] Enter the above parameters sequentially: reinforcing steel, sleeve, defect, cyclic load, and environmental parameters. Select "ordinary grout" as the grout type, and the system will automatically call the built-in parameter library to match the corresponding mechanical parameters.

[0098] Ordinary grouting material: grouting material compressive strength f cg =86.8MPa, elastic modulus E of grouting material g =30000MPa, bond strength between steel reinforcement and grout =2.504MPa, grout-sleeve bond strength =1.073MPa; Steel reinforcement material parameters (HRB400): Yield strength f y =400

[0099] MPa, ultimate strength f u0 =540MPa, elastic modulus E s =2.0×10 5 MPa; Sleeve material parameters (Q355): Yield strength f ys =355MPa.

[0100] The calculated ductility ratio μ of the grouting sleeve is 16.2, which is higher than the commonly used ductility ratio μ requirement of 5 in the standard, indicating that the grouting sleeve connector has good ductility when there are no defects; the ultimate tensile strength f of the grouting sleeve... u It is 540 MPa. Secant stiffness K c The effective bonding length L of the grout is 28.08 kN / mm. eff It is 154.0 mm, which is less than the anchorage length L. e This meets the anchorage length requirements.

[0101] All load parameters were calculated using the mechanical parameter calculation method, as shown in Table 1:

[0102] Table 1 Load parameters and corresponding results

[0103]

[0104] In the above results, the yield load of the reinforcing steel is... If the load is less than the ultimate critical load, it indicates that the specimen first undergoes steel yielding and enters the hardening stage; the minimum value of the ultimate critical load is... =169.6kN, therefore the axial ultimate bearing capacity P of the grouting sleeve connector is... ult The load is 169.6 kN. The primary failure mode is determined to be the ultimate tensile strength of the reinforcing steel, and the secondary control factor is the ultimate shear key bearing capacity. =170.2kN. The main failure mode is controlled by the ultimate tensile strength of the steel reinforcement, and the yield control state is that the steel reinforcement yields first.

[0105] Based on the above calculation results, the system automatically generates force-displacement curves, hysteresis curves, and load-strain curves, and verifies the indicators against the "Technical Specification for Mechanical Connection of Reinforcing Steel Bars": safety factor. / =169.6 / 125.7=1.35 (>1.2), ductility ratio 16.2 (>5), anchorage length ratio =160 / 20=8, and =154.0mm≤ =160mm. Finally, export a standardized report containing all calculated data and curves.

[0106] In the force-displacement curve, the linear elastic relationship is used to fit the load and displacement variation law in the elastic stage; in the plastic stage, an exponential decay model is introduced to consider the decay effects of ductility ratio, grouting defects and eccentricity, and differentiated degradation coefficients are set for the high-stress repeated tension-compression test and the large-deformation repeated tension-compression test respectively. The higher the strength of the grouting material, the gentler the descent of the curve, and the higher the ultimate bearing capacity. Figure 3 The force-displacement curve of the grouting sleeve shows that the load increases rapidly with displacement in the initial stage, then enters the yielding and strengthening stage, and decreases after reaching the ultimate bearing capacity. Point A in the figure is the loading start point, point B is the end point, and point C is the maximum value point, used to characterize the ultimate bearing state; point D is the slip inflection point, used to reflect the state where slip at the grouting interface of the sleeve begins to develop significantly; point E is the yield point, used to characterize the characteristic position of the specimen transitioning from the elastic stage to the plastic stage.

[0107] In the hysteresis curve, the cyclic iterative calculation was performed strictly according to the graded loading system of the high-stress repeated tension-compression test and the large deformation repeated tension-compression test in the "Technical Specification for Mechanical Connection of Reinforcing Steel". The calculation process simultaneously incorporated cyclic stiffness degradation, curve pinching effect and interface slip effect. The higher the elastic modulus of the grout, the weaker the pinching effect of the hysteresis curve, the smoother the stiffness degradation rate and the stronger the energy dissipation capacity. Figure 4 The figure shows the hysteresis curves for the first stage under repeated tensile and compressive stress. This figure indicates that the specimen develops a stable hysteretic response during cyclic loading, and the curve envelope reflects the load-bearing and deformation capacity of the nodes under repeated tensile and compressive stress. Point A in the figure is the starting point of the hysteresis curve; point B is the maximum value of the positive loading, used to characterize the first stage of the positive peak load-bearing state; point C is the minimum value of the negative loading, used to characterize the first stage of the reverse peak load-bearing state.

[0108] Based on the calculation formulas for longitudinal strain of steel bars and circumferential strain of sleeves in this invention, the corresponding longitudinal strain and circumferential strain are solved iteratively step by step according to the load step, and the load-strain correlation curve is automatically fitted, which can intuitively reflect the whole process of stress deformation development of grouting sleeve under repeated tension and compression.

[0109] Failure Mode Determination: The system uniformly solves for the critical loads of rebar yielding, ultimate tensile strength, pull-out, grout-sleeve interface, sleeve slippage, sleeve yielding, shear key shearing, shear key bearing, eccentric uneven stress, and grout defect bond failure. The rebar yielding critical load is output separately as the yield control state and is not included in the minimum ultimate failure load. Other ultimate critical loads are sorted by value from smallest to largest, and the failure mode corresponding to the minimum value is taken as the primary failure mode, with the second smallest value as the secondary failure mode. Simultaneously, the system can automatically determine the probability of interface pull-out and shear key failure based on the differences in the mechanical parameters of the three types of grout, providing a quantitative basis for material selection and sleeve structural design in grouting sleeve engineering.

[0110] After the system completes the calculations, all results can be exported as TXT text or XLSX spreadsheets. The exported content includes basic parameters, core mechanical indicators, failure mode determination results, standard verification conclusions, and curve coordinate data. All calculation conditions are automatically saved to a local history file, which can be retrieved at any time, and parameters can be modified and recalculated, facilitating multi-condition comparative analysis.

[0111] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A numerical simulation method for the mechanical properties of a grouting sleeve under repeated tensile and compressive stresses, characterized in that, Includes the following steps: S1. Obtain the basic parameters of the grouting sleeve connector according to the preset test and structural design requirements; S2. Solve for the reference mechanical parameters of the grouting sleeve under uniaxial tension based on the basic parameters; S3、Calculate the secant stiffness K of the grouting sleeve joint under repeated load c With stiffness degradation, and solve the key component failure load, slip load and grouting equivalent mechanical parameters in the process of cyclic loading; S4. Based on the actual stress conditions of the grouting sleeve, calculate the axial and circumferential strains, stresses, and reduced loads under the interaction of multiple factors of the reinforcing steel and the sleeve. S5. Summarize all types of ultimate loads and determine the axial ultimate bearing capacity of the grouting sleeve and the corresponding main failure modes; S6. Plot the force-displacement curve, hysteresis curve, and load-strain curve; compare the three curves with the preset "Technical Specification for Mechanical Connection of Reinforcing Steel" for compliance check, output the structural safety factor and damage risk warning, and give the optimal grouting material selection suggestion based on the comparison of multiple material libraries, and finally generate a standardized numerical simulation calculation report.

2. The numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve according to claim 1, characterized in that, The basic parameters in S1 include: steel grade, steel diameter d, and sleeve outer diameter D. out Sleeve inner diameter D in Bonding length L s Anchorage length L e Grouting material type, grouting material compressive strength f cg , grouting material elastic modulus E g , Bond strength between steel reinforcement and grout grout-sleeve bond strength , Eccentricity of force e, Grouting defect rate ξ, Shear key height h, Number of shear keys n k The number of load cycles n and the type of test load; The test loading types include high-stress repeated tension-compression test, large deformation repeated tension-compression test, and general repeated tension-compression test; The grouting material types include ordinary grouting material, ultra-high performance concrete and fiber concrete. The system automatically matches and calls its exclusive constitutive relationship and interface mechanical parameters according to the selected grouting material type.

3. The numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve according to claim 2, characterized in that, In step S2, the reference mechanical parameters include: ductility ratio of grouting sleeve μ, ultimate tensile strength of grouting sleeve f u , ultimate tensile load of steel bar P u , pull-out load of steel bar-grouting material interface P rg , pull-out load of grouting material-sleeve interface P gs , yield load of steel bar P y and yield load of sleeve P sleeve ; the calculation method of each reference mechanical parameter is specifically as follows: The calculation method for the ductility ratio μ of the grouting sleeve is as follows: ； In the formula, d is the diameter of the steel bar, in mm; ultimate tensile strength f of grouting sleeve u The calculation method is as follows: ； In the formula, f is the ultimate tensile strength of the grouting sleeve. u The unit is MPa; f u0 η represents the reference tensile strength of the reinforcing steel, in MPa. d α is the influence coefficient of grouting defect length. d L is the grouting defect location coefficient; e The anchorage length is in mm; L d The length of the grouting defect is in mm. Ultimate tensile load P of steel reinforcement u The calculation method is as follows: ； In the formula, A s This refers to the cross-sectional area of ​​the reinforcing bars, in mm². 2 Ultimate tensile load P of steel reinforcement u The unit is kN; d is the diameter of the steel bar, in mm; Pull-out load P at the rebar-grout interface rg The calculation method is as follows: ； In the formula, P is the pull-out load at the steel bar-grout interface. rg The unit is kN; η r The interface reinforcement coefficient generated by the rib constraint of the steel reinforcement; The bond strength between the steel reinforcement and the grout is expressed in MPa. Grouting material-sleeve interface pull-out load P gs The calculation method is as follows: ； In the formula, P is the pull-out load at the grout-sleeve interface. gs The unit is kN; η s D is the interfacial reinforcement coefficient resulting from the shear key on the inner wall of the sleeve and the surface roughness; in The inner diameter of the sleeve is in mm; The bonding strength between the grout and the sleeve is expressed in MPa. Reinforcement yield load P y The calculation method is as follows: ； In the formula, the yield load of the steel reinforcement is P y The unit is kN; f y This refers to the yield strength of the steel reinforcement, expressed in MPa. Sleeve yield load P sleeve The calculation method is as follows: ； In the formula, A st The cross-sectional area of ​​the sleeve is in mm². 2 Sleeve yield load P sleeve The unit is kN; f ys D represents the sleeve yield strength, in MPa. out The outer diameter of the sleeve is in mm.

4. The numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve according to claim 3, characterized in that, In step S3, the mechanical parameters of key component failure load, slip load, and grouting material include: shear key shear failure load P. kv Shear key bearing ultimate load P kc Sleeve slip load P slip Equivalent stiffness K of grouting material g Effective bonding length L with grout eff ; Secant stiffness K c The calculation method is as follows: ； In the formula, the secant stiffness K c The unit is kN / mm; h is the shear key height, in mm; Shear failure load P of shear key kv The calculation method is as follows: ； In the formula, the shear failure load P of the shear key is... kv The unit is kN; A k This represents the total cross-sectional area of ​​the shear key, in mm². 2 ;D in f is the inner diameter of the sleeve, in mm; cg The compressive strength of the grout is expressed in MPa. ultimate shear key bearing capacity P kc The calculation method is as follows: ； In the formula, P is the ultimate load of the shear key under bearing pressure. kc The unit is kN; Equivalent stiffness K of grouting material g The calculation method is as follows: ； In the formula, K represents the equivalent stiffness of the grouting material. g The unit is kN / mm; A g The effective annular cross-sectional area of ​​the grouting material is expressed in mm². 2 E g This refers to the elastic modulus of the grout, expressed in MPa. Effective bond length L of grout eff The calculation method is as follows: ； In the formula, L is the effective bonding length of the grout. eff The unit is mm; Sleeve slip load P slip The calculation method is as follows: ； In the formula, the sleeve sliding load P slip The unit is kN; The allowable limit slip is expressed in mm.

5. The numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve according to claim 4, characterized in that, In step S4, the circumferential strain, stress, and reduced load include: longitudinal strain ε of the reinforcing steel. l axial stress σ of steel bars s Circumferential strain ε of the sleeve h Circumferential equivalent stress σ of the sleeve t Eccentricity reduction load P ecc and grouting defect reduction load P def ; Axial stress σ of steel bars s The calculation method is as follows: ； In the formula, the axial stress σ of the steel bar s The unit is MPa; Circumferential equivalent stress σ of sleeve t The calculation method is as follows: ； In the formula, the circumferential equivalent stress σ of the sleeve t The unit is MPa; Calculate the longitudinal strain ε of the steel reinforcement according to the test loading type. l : ； In the formula, ε l0 σ represents the initial longitudinal strain of the reinforcing bar. s denoted as axial stress of the reinforcing bar, in MPa; k1 and k2 are strain correction factors, respectively. The circumferential strain ε of the sleeve is calculated according to the test loading type and zone. h : ； In the formula, ε h0 K represents the initial circumferential strain of the sleeve; k3 and k4 are strain correction coefficients, respectively. Eccentricity reduction load P ecc and grouting defect reduction load P def The calculation method is as follows: ； In the formula, the eccentricity reduces the load P. ecc The unit is kN; grouting defect reduction load P def The unit is kN; P base P is the ultimate tensile load of the steel reinforcement. u Pull-out load P at the rebar-grout interface rg Grouting material-sleeve interface pull-out load P gs Sleeve yield load P sleeve Shear failure load P of shear key kv Shear key bearing ultimate load P kc Sleeve slip load P slip The minimum value in; pull-out load P at the rebar-grout interface rg Pull-out load P at the grout-sleeve interface gs Not participating in P base The value is set so that the reduction only applies to the uncorrected load, avoiding repeated reductions.

6. The numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve according to claim 5, characterized in that, In step S5, the ultimate loads include: the ultimate tensile load P of the reinforcing steel. u Pull-out load P at the rebar-grout interface rg Grouting material-sleeve interface pull-out load P gs , Reinforcing steel yield load P y Sleeve yield load P sleeve Shear failure load P of shear key kv Shear key bearing ultimate load P kc Sleeve slip load P slip Eccentricity reduction load P ecc and grouting defect reduction load P def ; When determining the axial ultimate bearing capacity, the steel reinforcement yield load P is removed. y The minimum value of the external ultimate load is taken as the axial ultimate bearing capacity of the grouting sleeve.

7. The numerical simulation method for the repeated tensile and compressive mechanical properties of the grouting sleeve according to claim 6, characterized in that, The hysteresis curve generation method in step S6 is as follows: cyclic calculation is performed according to the graded loading system of the high stress repeated tension and compression test and the large deformation repeated tension and compression test in the specification. At the same time, the stiffness degradation, curve pinching effect and interface slip effect in the cycle process are considered, and the displacement and load correspondence is fitted one cycle at a time. The greater the stiffness of the grouting material, the weaker the pinching effect of the hysteresis curve, and the slower the stiffness degradation rate of the grouting sleeve connector.

8. A numerical simulation system for the mechanical properties of a grouting sleeve under repeated tensile and compressive stresses, characterized in that, Numerical simulation systems include: Parameter input module; Multi-type grouting material parameter library module; The multi-type grouting material parameter library module has built-in standard values ​​for compressive strength, elastic modulus and interfacial bond strength of three types of materials: ordinary grouting materials, ultra-high performance concrete and fiber concrete; Core calculation module; The core calculation module executes the numerical simulation method of repeated tensile and compressive mechanical properties of the grouting sleeve as described in any one of claims 1 to 7, and substitutes different grouting material parameters to complete the mechanical index calculation; Curve generation module; The curve generation module generates force-displacement curves, hysteresis curves, load-longitudinal strain curves, and load-circumferential strain curves based on the calculation results; The results display module and the report export module.

9. The numerical simulation system for the repeated tensile and compressive mechanical properties of the grouting sleeve according to claim 8, characterized in that, The numerical simulation system automatically matches the corresponding grouting material parameters, completes the comparison of the mechanical properties of the grouting sleeve under different working conditions, and provides suggestions for the selection of grouting material and optimization schemes for the sleeve structure.

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