Self-resetting filler wall frame four-broken-line load-displacement curve prediction model construction method

Abstract

The invention provides a self-resetting filler wall frame four-broken-line load-displacement curve prediction model construction method. According to the method, the nonlinear response of the structure is decomposed into four linear stages with obvious physical significance, namely an elastic stage, an elastic-plastic stage, a plastic stage and a recovery stage. The model is based on a mechanical model and a deformation coordination relation of structural key components (prestressed steel bars, energy consumption angle steel and reinforced concrete), and analytical calculation is carried out by establishing a force balance equation of nodes. The provided four-broken-line analytical model can quickly predict the complete nonlinear response of the self-resetting framework without complex iterative calculation or large-scale finite element analysis, the original analysis process of several hours is shortened to the minute level, and the scheme comparison, selection and optimization efficiency in the design stage is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of seismic design and analysis technology for structural engineering, and in particular to a method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame. Background Technology

[0002] Self-setting structures, as a cutting-edge direction in modern earthquake engineering, can reduce deformation participation through components such as prestressed steel bars and dissipate energy through energy-dissipating devices at nodes. After an earthquake, only the energy-dissipating components need to be replaced, demonstrating significant advantages in repairability, functional recovery speed, and life-cycle cost. They have become an important development direction for high-performance earthquake-resistant structures. Current research on self-setting structures mainly focuses on experimental research and numerical simulation. Numerous quasi-static tests and shaking table tests have revealed the typical "flag-shaped" hysteresis curve characteristics of self-setting structures: a distinct yield point, a stiffening segment, a bearing capacity plateau, and good unloading stiffness. In numerical simulation, finite element analysis is widely used to simulate the complex nonlinear behavior of self-setting structures. However, while refined finite element models offer high accuracy, they are complex to model and computationally time-consuming, making them difficult to directly apply to preliminary engineering design and rapid evaluation.

[0003] In engineering practice, simplified restoring force models are of irreplaceable importance for structural seismic design, elastoplastic analysis, and performance evaluation. For traditional reinforced concrete frame structures, bilinear models, trilinear models, and others have been widely used and incorporated into design codes of various countries. These simplified models describe the nonlinear mechanical behavior of the structure through a few key parameters (such as initial stiffness, yield capacity, peak capacity, and degraded stiffness), providing engineers with efficient analysis tools.

[0004] However, the mechanical behavior of self-setting infill wall structures differs fundamentally from that of traditional structures: 1) They exhibit a distinct opening-closing mechanism: under load, the restoring force provided by the prestressing tendons causes the beam-column contact surface to repeatedly open and close; 2) They exhibit significant stiffness variation characteristics: as the degree of node opening changes, the structural stiffness shows obvious stage-wise changes; 3) Energy dissipation and the restoring mechanism are coupled: the mechanical behavior of replaceable energy dissipation components is coupled with and influences the prestressing restoring mechanism; 4) The presence of infill walls further affects the seismic performance of self-setting structures, and the interaction between the walls and the frame affects the feature points of the simplified model. These unique characteristics make it impossible for traditional bi-linear or tri-linear models to accurately describe the actual mechanical behavior of self-setting structures.

[0005] In performance-based seismic design, it is necessary to predict the structural response under earthquakes of varying intensities. A simplified analytical model that accurately reflects the complete stress process of a self-setting frame is therefore crucial. Such a model should be able to describe the complete process of the structure from the elastic stage to initial node opening, from the yielding of energy-dissipating elements to full development, and from load-bearing capacity strengthening to the ultimate limit state. It should also consider stiffness recovery and residual deformation control characteristics during unloading.

[0006] Therefore, developing a four-segment load-displacement curve prediction model for self-resetting frames with clear physical meaning, simple parameter determination, and good prediction accuracy is of great theoretical and engineering value for promoting the engineering application of self-resetting structures, simplifying the design process, and realizing performance-based seismic design. Summary of the Invention

[0007] The purpose of this invention is to address the problems in existing technologies by proposing a method for constructing a four-segment load-displacement curve prediction model for self-resetting infill wall frames. This model is applicable to self-resetting concrete frame structures with prestressed reset mechanisms and replaceable energy-dissipating components. The model is primarily used to predict and evaluate the nonlinear mechanical behavior of self-resetting frames under horizontal loads during the structural design phase, providing a key analytical tool for performance-based seismic design.

[0008] This invention is achieved through the following technical solution: This invention proposes a method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame, the method comprising: Finite element model construction and stage division: Based on the seismic test results of self-resetting structures, a finite element model of a self-resetting infill wall frame is established. In the recovery stage, only the prestress in the prestressed steel bars is applied. The four stages of the self-resetting infill wall frame are determined using the finite element model results: elastic stage, elastoplastic stage, plastic stage and recovery stage. Mechanical analysis of key points in four stages of bare frame: For self-resetting bare frame, the forces at each turning point are not assumed, but obtained by solving the micromechanical equations of the nodes; taking the core area of ​​the node opening as the isolation body, the tensile force of the prestressed steel bars, the tensile and compressive forces of the energy dissipating angle steel, the resultant force of the concrete compression zone of the beam and column, and the stress of the steel bars are considered; among them, since the elongation of the prestressed steel bars is unknown, it is necessary to establish deformation compatibility equations and use iterative methods to determine the final prestress; Simplification and linear superposition of infill walls: For self-resetting infill wall frames, the complex role of infill walls is simplified using the equivalent diagonal compression bar theory; based on the crack propagation mode observed in the experiment, the infill wall is simplified into one or more compression bars hinged to the frame; the geometric and material properties of the diagonal compression bars are analyzed, and their lateral stiffness and bearing capacity provided to the frame are calculated; the overall response of the self-resetting infill wall frame is obtained by linearly superimposing the contributions of the bare frame's four-segment model with those of the infill walls. Validation of simplified model results: After obtaining the simplified load-displacement curves of the self-resetting bare frame and the infill wall frame, the key parameters of the finite element model established above were changed. The simplified load-displacement curves were calculated using the changed parameters and compared with the finite element model to verify the accuracy of the simplified model.

[0009] Furthermore, in the process of finite element model construction and stage division, ABAQUS is used to establish the finite element model, and prestress is applied by the cooling method;

[0010] In the formula: To lower the temperature; Prestress in prestressed steel bars; λ The coefficient of thermal expansion of prestressed steel bars is... E p This is the elastic modulus of prestressed steel bars.

[0011] Further, the elastic stage: at this stage, all components are in an elastic state, and the bearing capacity is determined by the initial stiffness and the displacement in the elastic stage. At the end of this stage, the pressure on the beam-column contact surface is zero, and the joint is about to unfold. The elastoplastic stage: as the horizontal displacement increases, the angle steel gradually yields, and the concrete begins to spall. When the angle steel reaches the yield point, it is considered that the structure has reached the end of the elastoplastic stage, and the resistance of the self-resetting structure reaches its peak value. The plastic stage: after the bearing capacity reaches its peak value, it decreases. The end of the plastic stage is when the bearing capacity reaches 75% of the peak value. The recovery stage: when the external load is unloaded, the components recover to their residual displacement with the prestress. This corresponds to the end of the recovery stage.

[0012] Furthermore, in the four-stage key point mechanical analysis of the bare frame, the relationship between the bending capacity of the self-centering bare frame and the bearing capacity of the two columns is determined by the following formula:

[0013] In the formula: F lc , F rc The shear force of the columns on the left and right sides; α i This is the bearing capacity coefficient.

[0014] Furthermore, the bearing capacity at the end of the elastic stage is determined by establishing a force balance equation when the joint is about to open; the bearing capacity at the end of the elastic-plastic stage corresponds to the obvious yielding of the energy-dissipating angle steel; the bearing capacity at the end of the plastic stage is taken as 75% of the peak bearing capacity, at which point the height of the concrete compression zone can be calculated; the bearing capacity at the end of the recovery stage is 0, confirming the recovery displacement through prestressing.

[0015] Furthermore, in the simplification and linear superposition process of the infill wall, cracks first develop near the two sides of the column in the experiment, and then the cracks develop towards the center; at the end of the elastic stage of the frame, the infill wall develops cracks near the two sides of the column, and at the end of the elastoplastic stage, the wall develops cracks towards the center; the compression members formed by the infill wall are determined by these two development paths, thereby determining the contribution of the infill wall to the bearing capacity, divided into the end of the elastic stage and the end of the elastoplastic stage. The displacements at the elastic and elastoplastic stages are the same as those of the bare frame. The bearing capacities of the two stages are superimposed to determine the bearing capacity of the self-resetting infill wall structure; the bearing capacity of the plastic stage is taken as half of the peak bearing capacity of the infill wall; the calculation method of the recovery stage is consistent with that of the bare frame, and the stiffness adopts the overall stiffness with the infill wall, thus determining the four-segment simplified model of the self-resetting infill wall structure.

[0016] Furthermore, in the process of verifying the simplified model results, core design variables that have a significant impact on the mechanical properties of the self-resetting frame were selected, including: the magnitude of prestress, the vertical axial compression ratio, and the strength of the infill wall.

[0017] Furthermore, perform parametric finite element analysis: for each set of changed parameter combinations, run the corresponding refined finite element model, perform a complete quasi-static loading analysis, and directly extract its load-displacement skeleton curve as the "real" response. Simultaneous calculation using a simplified model: Input the same parameter changes into the four-segment simplified model, and quickly calculate the simplified load-displacement curves under the corresponding parameters based on its inherent mechanical analytical formulas; Comparison and error analysis: The curves predicted by the simplified model are compared and analyzed with the finite element results in multiple dimensions.

[0018] The present invention also proposes an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame.

[0019] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of the method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame.

[0020] The beneficial effects of this invention are: 1) Significantly improve design and analysis efficiency: The proposed four-segment analytical model can quickly predict the complete nonlinear response of the self-resetting frame without complex iterative calculations or large-scale finite element analysis, reducing the analysis process from several hours to minutes, and greatly improving the efficiency of scheme comparison and optimization in the design stage.

[0021] 2) Achieve accurate prediction of mechanical properties: The model is based on clear physical and mechanical mechanisms and can accurately predict the bearing capacity, stiffness and residual deformation of the structure under various key states (such as node opening, angle steel yielding and peak load). The prediction results are in good agreement with refined finite element analysis and experimental data, providing a reliable tool for performance-based seismic design.

[0022] 3) The realism of finite element simulation: The recovery section adopts the method of recovery based solely on prestress, which is closer to the actual situation of structural deformation and has good engineering practical value. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the finite element simulation process of the self-resetting frame of the present invention.

[0025] Figure 2 This is a stress analysis diagram of the self-resetting infill wall frame of the present invention.

[0026] Figure 3 This is a comparison chart of the finite element simulation and experimental results of the self-resetting infill wall frame of the present invention.

[0027] Figure 4 This is a force analysis diagram of the elastic stage column of the present invention.

[0028] Figure 5 This is a stress analysis diagram of the column in the elastoplastic stage of the present invention.

[0029] Figure 6 This is a stress analysis diagram of the column during the plasticity and recovery stages of the present invention.

[0030] Figure 7 This is a schematic diagram illustrating the calculation process of parameters for the development mode of cracks in infilled walls in this invention.

[0031] Figure 8 This is a schematic diagram comparing the results of the four-segmented line analytical model and the finite element method in this invention.

[0032] The markings and parameters in the diagram are as follows: 1-Prestressed steel reinforcement, 2-Beam prestressed steel reinforcement, 3-Column prestressed steel reinforcement, 4-Column steel reinforcement. M - Column base bending moment T i0 - Initial prestressing F p-Actuator pressure h- Column cross-section height, K fm , K fs - The bending and shear stiffness of the frame, I f -Moment of inertia of the frame, E f , G w - Elastic modulus and shear modulus of concrete L i - Distance from the top of the foundation to the bottom of the beam h b - Beam section height, A w - Cross-sectional area of ​​the frame, M p - The flexural strength provided by prestressed steel bars M s - The bending load-bearing capacity provided by angle steel T ptc,i -No. i The tensile force of the prestressed steel bars, c ep - Height of the compression zone of concrete at the end of the elastoplastic stage - Tensile force on the reinforcing steel bars at the column base t a -Thickness of the vertical limb of the angle steel k pt -Stiffness of prestressed steel reinforcement in column-concrete sections - Elongation of prestressed steel bars C c - Concrete pressure at column base T cs -Reinforcing steel stress, f y - Yield strength of steel reinforcement A cs - Cross-sectional area of ​​reinforcing steel bars β 1-Ratio of the height to the depth of the neutral axis of the equivalent stress rectangular concrete block. f c - Concrete compressive strength b- Concrete width, -Deformation of tensile angle steel t a - Angle steel thickness, F p1 - The load-bearing capacity of the frame at the end of the plastic phase. T ptc,pi , T ptc,rsi-Prestressing of prestressed steel bars at the end of the plastic stage and the end of the recovery stage. F ep,b - The infill wall forms a compression bar on both sides of the column. α - The angle between the compression members on both sides of the column and the vertical direction, a ep - Width of the compression members near the sides of the column t inf - Block thickness f m - Compressive strength of the blocks, λ ep - Determine the equivalent width coefficient of the compression members on both sides of the column. L c - The distance between the foundation and the centerline of the beam r ep,i - Length of the compression members on both sides of the column E i - The elastic modulus of the infill wall, E f - The elastic modulus of the concrete frame, I b -Moment of inertia of the column section, L i - One span of infill wall length K infm , K infs - Bending and shear stiffness of infill walls I inf -Moment of inertia of the infill wall E inf , G inf - Elastic modulus and shear modulus of the infill wall A inf - Cross-sectional area of ​​the infill wall The shear slip weakening coefficient of the infill wall's shear bearing capacity can be taken as 0.5. F p,b - Diagonal compression bar pressure β - The angle between the diagonal compression bar and the vertical direction a p - Diagonal compression bar width λ p - Determine the equivalent width factor for the diagonal compression bar. r p,i - Diagonal compression bar length. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The self-resetting infill wall frame four-segment load-displacement prediction model proposed in this invention works by decomposing the nonlinear response of the structure into four linear stages with distinct physical meanings: elastic, elastoplastic, plastic, and recovery stages. Based on the mechanical model and deformation compatibility relationships of key structural components (prestressed steel bars, energy-dissipating angle steel, and reinforced concrete), the model performs analytical calculations by establishing force balance equations for the nodes.

[0035] Specifically, in combination Figures 1-8 This invention proposes a method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame, the method comprising: Finite element model construction and stage division: Based on the seismic test results of self-resetting structures, a finite element model of a self-resetting infill wall frame is established. In the recovery stage, only the prestress in the prestressed steel bars is applied. The four stages of the self-resetting infill wall frame are determined using the finite element model results: elastic stage, elastoplastic stage, plastic stage and recovery stage. In the process of finite element model construction and stage division, ABAQUS is used to build the finite element model, and the simulation steps are as follows: Figure 1 As shown, prestress is applied by cooling method;

[0036] In the formula: To lower the temperature; Prestress in prestressed steel bars; λ The coefficient of thermal expansion for prestressed steel bars can be taken as 1.2 × 10⁻⁶. -5 , E p This is the elastic modulus of prestressed steel bars.

[0037] After loading, a new stage is added: structural recovery using prestress. Materials and test dimensions are consistent, and a refined finite element modeling method is employed. Concrete, embedded steel components, angle steel, and blocks are modeled using solid elements (C3D8R), while reinforcing bars and prestressed steel bars are modeled using truss elements. After applying prestress, vertical loads, and horizontal loads, the frame skeleton curve is obtained. Based on the obtained skeleton curve, it can be divided into four stages: Elastic stage: At this stage, all components are elastic, and the bearing capacity is determined by the initial stiffness and displacement during the elastic stage. At the end of this stage, the pressure at the beam-column contact surface is zero, and the joints are about to unfold. Elastic-plastic stage: As the horizontal displacement increases, the angle steel gradually yields, and the concrete begins to spall. When the angle steel reaches the yield point, the structure is considered to have reached the end of the elastic-plastic stage, at which point the resistance of the self-resetting structure reaches its peak. Plastic stage: The bearing capacity decreases after reaching its peak value, and the end of the plastic stage is reached when the bearing capacity reaches 75% of its peak value. Recovery stage: After unloading the external load, the components recover to their residual displacement with the prestress, corresponding to the end of the recovery stage.

[0038] Mechanical analysis of key points in four stages of bare frame: For self-resetting bare frame, the forces at each turning point are not assumed, but obtained by solving the micromechanical equations of the nodes; taking the core area of ​​the node opening as the isolation body, the tensile force of the prestressed steel bars, the tensile and compressive forces of the energy dissipating angle steel, the resultant force of the concrete compression zone of the beam and column, and the stress of the steel bars are considered; among them, since the elongation of the prestressed steel bars is unknown, it is necessary to establish deformation compatibility equations and use iterative methods to determine the final prestress; This invention analyzes the mechanical model of a self-resetting infill wall frame and proposes a method for determining the four-stage characteristic points of a self-resetting bare frame. The mechanical model of the self-resetting infill wall frame is as follows: Figure 2 As shown. In the four-stage key point mechanical analysis of the bare frame, the relationship between the bending capacity of the self-centering bare frame and the bearing capacity of the two columns is determined by the following formula:

[0039] In the formula: F lc , F rc The shear force of the columns on the left and right sides; α i The bearing capacity coefficient can be taken as 0.7.

[0040] The bearing capacity at the end of the elastic stage is determined by establishing the force equilibrium equations when the joint is about to open. At this point, the structure is in a linear elastic state, the prestressed steel bars maintain their initial prestress, and the angle steel has not yet played its role. The flexural bearing capacity of the joint at this time consists of two parts: the prestress in the prestressed steel bars and the vertical compressive force. This allows us to determine the bearing capacity at the end of the elastic stage. After determining the stiffness of the elastic stage, the corresponding displacement can be determined.

[0041] The bearing capacity at the end of the elastoplastic stage corresponds to the significant yielding of the energy-dissipating angle steel; the joint is fully open, but since the joint displacement and the elongation of the prestressed steel are unknown at this point, it is necessary to assume that the prestress is equal to the initial prestress. The joint rotation and the elongation of the prestressed steel are calculated using the deformation compatibility relationship, and then the prestress is updated and substituted into the force equilibrium equation for verification. By iteratively adjusting the displacement until the equilibrium equation is satisfied, the convergent solution can simultaneously determine the corresponding displacement and the elongation of the prestressed steel, thereby determining the bearing capacity.

[0042] The bearing capacity at the end of the plastic stage is taken as 75% of the peak bearing capacity, at which point the height of the concrete compression zone can be calculated.

[0043] At the end of the recovery stage, the bearing capacity is 0, confirming the recovery displacement through prestress. The recovered displacement can be obtained from the mean value of the prestress and the residual stiffness. Since the residual deformation is uncertain, the prestress needs to be solved using an iterative method. Assuming the prestress is the same as at the end of the plastic stage, the corresponding displacement is obtained, and then the prestress at this point is calculated using the deformation compatibility relationship. The displacement is iteratively adjusted until the equilibrium equation is satisfied, thus determining the prestress and the corresponding residual deformation at this point.

[0044] Simplification and linear superposition of infill walls: For self-resetting infill wall frames, the complex role of infill walls is simplified using the equivalent diagonal compression bar theory; based on the crack propagation mode observed in the experiment, the infill wall is simplified into one or more compression bars hinged to the frame; the geometric and material properties of the diagonal compression bars are analyzed, and their lateral stiffness and bearing capacity provided to the frame are calculated; the overall response of the self-resetting infill wall frame is obtained by linearly superimposing the contributions of the bare frame's four-segment model with those of the infill walls. In the simplification and linear superposition process of the infill wall, this invention determines the equivalent diagonal strut model of the infill wall based on experimental phenomena and calculates its contribution to the bearing capacity of the self-resetting frame. In the experiment, cracks first develop near the two sides of the column, and then the cracks develop towards the center; at the end of the elastic stage of the frame, the infill wall develops cracks near the two sides of the column, and at the end of the elastoplastic stage, the wall develops cracks towards the center; the struts formed by the infill wall are determined by these two development paths, thereby determining the contribution of the infill wall to the bearing capacity, divided into the end of the elastic stage and the end of the elastoplastic stage. The displacements at the elastic and elastoplastic stages are the same as those of the bare frame. The bearing capacities of the two stages are superimposed to determine the bearing capacity of the self-resetting infill wall structure; the bearing capacity of the plastic stage is taken as half of the peak bearing capacity of the infill wall; the calculation method of the recovery stage is consistent with that of the bare frame, and the stiffness adopts the overall stiffness of the infill wall, thus determining the four-segment simplified model of the self-resetting infill wall structure.

[0045] Validation of simplified model results: After obtaining the simplified load-displacement curves of the self-resetting bare frame and the infill wall frame, the key parameters (such as prestress, axial force, infill wall strength, etc.) of the finite element model established above were changed. The simplified load-displacement curves were calculated using the changed parameters and compared with the finite element model to verify the accuracy of the simplified model.

[0046] After obtaining the simplified load-displacement curves of the self-resetting bare frame and infill wall frame predicted based on the four-segment line model, the model needs to be systematically parametrically verified to confirm its accuracy within the range of design parameter variations. Therefore, this invention uses the established refined finite element model as a benchmark to carry out the following verification work: Define the range of variation for key parameters: Select core design variables that have a significant impact on the mechanical properties of the self-resetting frame, including: 1) the magnitude of prestress, which is adjusted by a certain proportion (e.g., ±20%) based on the initial design value; 2) the vertical axial compression ratio, which covers the range from low axial compression (e.g., 0.2) to the higher axial compression allowed by the code (e.g., 0.8); 3) the strength of the infill wall (e.g., the compressive strength of masonry), which is set according to the grade of commonly used materials (e.g., M5 to M15).

[0047] Perform parametric finite element analysis: For each set of changed parameter combinations, run the corresponding refined finite element model, perform a complete quasi-static loading analysis, and directly extract its load-displacement skeleton curve as the "real" response. Simultaneous calculation using a simplified model: Input the same parameter changes into the four-segment simplified model, and quickly calculate the simplified load-displacement curves under the corresponding parameters based on its inherent mechanical analytical formulas (such as nodal equilibrium iteration, equivalent diagonal compression bar calculation, etc.). Comparison and error analysis: The curves predicted by the simplified model are compared and analyzed with the finite element results in multiple dimensions, focusing on: the accuracy of bearing capacity and displacement prediction at the inflection points of each characteristic stage; the degree of shape fit of the overall skeleton curve; and the accuracy of prediction of unloading stiffness and residual deformation.

[0048] This invention proposes a method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame. Its core innovations are: 1) A four-stage analytical model driven by physical mechanisms: The complex nonlinear response of the self-resetting frame is clearly divided into four physical stages: elastic, elastoplastic, plastic, and recovery. By establishing the mechanical equilibrium equations and deformation compatibility equations for the nodal isolation bodies, an iterative algorithm is used to directly and analytically solve the forces and displacements at the inflection points of each stage, giving the model a clear mechanical meaning; 2) A simplified method for the infill wall: The infill wall is simplified as an equivalent diagonal compression member, and its hinged mechanical model with the frame is derived. The analytical results of the bare frame are linearly superimposed with the response of the diagonal compression member of the infill wall; 3) A finite element modeling method with a recovery stage: A finite element model based on prestress recovery is established, and the accuracy of the four-segment analytical model is verified by changing the parameters.

[0049] Example The implementation of the present invention will be described in detail below with reference to a specific embodiment. This embodiment is used to fabricate a full-scale frame specimen with a single-story, single-span structure, self-resetting nodes, and masonry infill walls for model verification.

[0050] This invention proposes a method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame, which specifically includes the following steps: Step 1: Establishment of finite element model and comparison and verification of experimental results; This embodiment employs refined finite element modeling using ABAQUS. The concrete constitutive model uses a plastic damage CDP model, while the steel constitutive model uses a bilinear model. Contact between blocks is represented by cohesive behavior, and contact between steel reinforcement and concrete uses an embedded contact mode. The friction coefficient between high-strength bolts and concrete is set to 0.7, and the overall friction coefficient for the entire component is set to 0.3. The simulation process first applies prestress using a cooling method, followed by sequential application of vertical axial force and horizontal force. After loading, the displacement is restored using prestress. Comparison of the results with experimental results shows that the bearing capacity error is less than 10%, and the development of plastic deformation is consistent with the experiment, indicating that the finite element modeling method is accurate. Figure 3 As shown.

[0051] Step 2: Determination of the four-segment analytical model of the self-resetting bare frame; In this embodiment, the finite element model of the self-resetting bare frame and the skeleton curve are used to determine its four-segment line analytical model parameters using the method of this invention. First, the relevant geometric parameters are input: concrete column size 300mm × 300mm, strength grade C40, and prestressed steel reinforcement. f ptk 1560MPa, angle steel strength 235MPa, cross section 1800mm² 2The axial compression ratio is 0.2, and the shear and flexural stiffness of the concrete are both based on the values ​​given in the specifications.

[0052] At the end of the elastic phase, adopt Figure 4 The formulas derived from the stress analysis determine the bearing capacity and displacement of the corresponding bare frame. First, the bending stiffness is determined, thereby determining the bearing capacity. Then, the overall stiffness of the frame at this point is used to determine the displacement corresponding to the end of the elastic stage.

[0053]

[0054]

[0055]

[0056]

[0057]

[0058] At the end of the elastic-plastic stage, the flexural bearing capacity is adopted. Figure 5 Formula (1) derived from the stress analysis is determined

[0059] The elongation of the prestressed steel bars is unknown. This is related to the joint opening angle, and determining the joint opening angle allows us to determine the corresponding displacement. Using... Figure 5 Formulas (2)-(7) are used to iteratively solve for the elongation and corresponding displacement of prestressed steel bars.

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066] At the end of the plasticity and recovery phase, using Figure 6 The formula is derived from the stress analysis. At the end of the plastic stage, the bearing capacity decreases significantly; the bearing capacity can be taken as 75% of the peak bearing capacity. The corresponding displacement can be solved using the residual stiffness, such as... Figure 6 Formula (1) is used to determine this.

[0067]

[0068] At the end of the recovery phase, the bearing capacity is 0, and the displacement is determined through an iterative method using... Figure 6 Formulas (2)-(5) in the formula are used to determine the formula.

[0069]

[0070]

[0071]

[0072]

[0073] Step 3: Determine the analytical model of the four-segment line of the self-resetting infill wall frame; In this embodiment, the contribution of the infill wall is considered after calculating the load-bearing capacity of the bare frame. Based on experimental phenomena, the crack development patterns of the infill wall are divided into those near the columns and those diagonally. The relevant parameters of the struts near the columns are determined by... Figure 7 Formulas (1)-(4) in the formulas determine the following:

[0074]

[0075]

[0076]

[0077] The struts formed diagonally are made of Figure 7 Formulas (8)-(11) in the formula are used to determine the formula.

[0078]

[0079]

[0080]

[0081]

[0082] The load-bearing capacity of the infill wall and the bare frame is superimposed, and in the elastic stage, it is... Figure 7 Formulas (5)-(7) in the formula determine the stiffness of the infilled wall at this time, and thus determine the corresponding displacement.

[0083]

[0084]

[0085]

[0086] The displacement corresponding to the elastoplastic stage is from Figure 7Formula (12) in the middle is determined.

[0087]

[0088] At the end of the plastic stage, the load-bearing capacity of the infill wall is taken as 50% of the peak value, and the displacement is consistent with that of the bare frame. The calculation process for the recovery stage is the same as that for the bare frame, except that the overall stiffness is determined using the stiffness of the infill wall at this point. Using the above method, the load-displacement four-segment analytical model of the self-resetting infill wall frame can be obtained.

[0089] Step 4: Cutting special blocks and constructing infill walls; The accuracy of the invention was verified by comparing the analytical model with the simulation results of ABAQUS. The curves formed by the four-segment line analytical model and the skeleton curves of the frame were plotted on the same coordinate axis to verify the accuracy of the fit. Particular attention was paid to the fitting accuracy between the key points of the four-segment line and the skeleton curves. Parameters such as beam and column prestress, block strength, and axial compression ratio were changed, and these parameters were recalculated using the analytical model. Specific parameters are as follows: Figure 8 The table below shows a comparison between analytical and simulation results. Figure 8 As shown in the curve graph, it can be determined that the analytical model fits the data well.

[0090] The present invention also proposes an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame.

[0091] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of the method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame.

[0092] The memory in this application embodiment can be volatile memory or non-volatile memory, or it can include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory used in the methods described in this invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0093] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0094] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly implemented by a hardware processor, or by a combination of hardware and software modules in the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0095] It should be noted that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuitry in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied as execution by a hardware decoding processor, or as a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0096] The above provides a detailed description of the method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame proposed in this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for constructing a four-segment load-displacement curve prediction model for a self-resetting infill wall frame, characterized in that, The method includes: Finite element model construction and stage division: Based on the seismic test results of self-resetting structures, a finite element model of a self-resetting infill wall frame is established. In the recovery stage, only the prestress in the prestressed steel bars is applied. The four stages of the self-resetting infill wall frame are determined using the finite element model results: elastic stage, elastoplastic stage, plastic stage and recovery stage. Mechanical analysis of key points in four stages of bare frame: For self-resetting bare frame, the forces at each turning point are not assumed, but obtained by solving the micromechanical equations of the nodes; taking the core area of ​​the node opening as the isolation body, the tensile force of the prestressed steel bars, the tensile and compressive forces of the energy dissipating angle steel, the resultant force of the concrete compression zone of the beam and column, and the stress of the steel bars are considered; among them, since the elongation of the prestressed steel bars is unknown, it is necessary to establish deformation compatibility equations and use iterative methods to determine the final prestress; Simplification and linear superposition of infill walls: For self-resetting infill wall frames, the complex role of infill walls is simplified using the equivalent diagonal compression bar theory; based on the crack propagation mode observed in the experiment, the infill wall is simplified into one or more compression bars hinged to the frame; the geometric and material properties of the diagonal compression bars are analyzed, and their lateral stiffness and bearing capacity provided to the frame are calculated; the overall response of the self-resetting infill wall frame is obtained by linearly superimposing the contributions of the bare frame's four-segment model with those of the infill walls. Validation of simplified model results: After obtaining the simplified load-displacement curves of the self-resetting bare frame and the infill wall frame, the key parameters of the finite element model established above were changed. The simplified load-displacement curves were calculated using the changed parameters and compared with the finite element model to verify the accuracy of the simplified model.

2. The method according to claim 1, characterized in that, In the process of finite element model construction and stage division, ABAQUS is used to establish the finite element model and prestress is applied by the cooling method. In the formula: To lower the temperature; Prestress in prestressed steel bars; λ The coefficient of thermal expansion of prestressed steel bars. E p This is the elastic modulus of prestressed steel bars.

3. The method according to claim 1, characterized in that, Elastic stage: At this stage, all components are in an elastic state. The bearing capacity is determined by the initial stiffness and the displacement during the elastic stage. At the end of this stage, the pressure at the beam-column contact surface is zero, and the joint is about to unfold. Elastic-plastic stage: As the horizontal displacement increases, the angle steel gradually yields, and the concrete begins to spall. When the angle steel reaches the yield point, the structure is considered to have reached the end of the elastic-plastic stage, and the resistance of the self-resetting structure reaches its peak value. Plastic stage: The bearing capacity decreases after reaching its peak value. The end of the plastic stage is when the bearing capacity reaches 75% of its peak value. Recovery stage: The external load is unloaded, and the components recover to their residual displacement with the prestress. This corresponds to the end of the recovery stage.

4. The method according to claim 1, characterized in that, In the four-stage key point mechanical analysis of the bare frame, the relationship between the bending capacity of the self-centering bare frame and the bearing capacity of the two columns is determined by the following formula: In the formula: F lc , F rc The shear force of the columns on the left and right sides; α i This is the bearing capacity coefficient.

5. The method according to claim 1, characterized in that, The bearing capacity at the end of the elastic stage is determined by establishing a force balance equation when the joint is about to open; the bearing capacity at the end of the elastic-plastic stage corresponds to the obvious yielding of the energy-dissipating angle steel; the bearing capacity at the end of the plastic stage is taken as 75% of the peak bearing capacity, at which point the height of the concrete compression zone can be calculated; the bearing capacity at the end of the recovery stage is 0, confirming the recovery displacement through prestressing.

6. The method according to claim 1, characterized in that, In the simplification and linear superposition process of the infill wall, cracks first develop near the sides of the column in the experiment, and then the cracks develop towards the center. At the end of the elastic stage of the frame, the infill wall develops cracks near the sides of the column, and at the end of the elastoplastic stage, the wall develops cracks towards the center. The compression members formed by the infill wall are determined by these two development paths, thereby determining the contribution of the infill wall to the bearing capacity. It is divided into the end of the elastic stage and the end of the elastoplastic stage. The displacements at the elastic and elastoplastic stages are the same as those of the bare frame. The bearing capacities of the two stages are superimposed to determine the bearing capacity of the self-resetting infill wall structure. The bearing capacity of the plastic stage is taken as half of the peak bearing capacity of the infill wall. The calculation method of the recovery stage is the same as that of the bare frame, and the stiffness adopts the overall stiffness of the infill wall, thus determining the four-segment simplified model of the self-resetting infill wall structure.

7. The method according to claim 1, characterized in that, In the process of verifying the simplified model results, the core design variables that have a significant impact on the mechanical properties of the self-resetting frame were selected, including: the magnitude of prestress, the vertical axial compression ratio, and the strength of the infill wall.

8. The method according to claim 7, characterized in that, Perform parametric finite element analysis: For each set of changed parameter combinations, run the corresponding refined finite element model, perform a complete quasi-static loading analysis, and directly extract its load-displacement skeleton curve as the "real" response. Simultaneous calculation using a simplified model: Input the same parameter changes into the four-segment simplified model, and quickly calculate the simplified load-displacement curves under the corresponding parameters based on its inherent mechanical analytical formulas; Comparison and error analysis: The curves predicted by the simplified model are compared and analyzed with the finite element results in multiple dimensions.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-8.

10. A computer-readable storage medium for storing computer instructions, characterized in that, When the computer instructions are executed by the processor, they implement the steps of the method according to any one of claims 1-8.

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