Slab-shell type pipeline supporting piece safety checking and evaluating method for nuclear power field

Abstract

The invention discloses a safety checking and evaluating method for a plate-shell type pipeline supporting piece in the nuclear power field. The method establishes a computer model of the support; related loads and constraints are applied according to the computer model of the supporting piece and working conditions for subsequent simulation and evaluation; simulation processing is conducted on the computer model of the supporting piece, then working condition combination analysis is conducted according to simulation results, and stress results of the shell unit are obtained through extraction according to different conditions; and according to the extracted stress result of the shell unit, supporting piece structure checking is carried out on different supporting piece objects. The method is an automatic checking solution for the nuclear-grade plate shell type supporting piece, a checking solution for the nuclear-grade supporting piece is provided, a corresponding checking algorithm is provided according to the solution, the checking comprehensiveness and accuracy are improved, and the design efficiency of the nuclear-grade supporting piece is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear power and construction engineering simulation design, and in particular relates to a structural safety verification and assessment method for plate and shell type pipeline supports used in the nuclear power field. Background Art

[0002] Support structures are widely used in industrial engineering projects in my country. As a crucial support structure for pipeline components, they are an integral part of pipeline engineering design. The design quality of support structures directly impacts the proper operation of suspended pipelines, so their stability must be ensured in practical applications. Prior to installation, the safety of support structure design must be fully considered.

[0003] At present, there are two main methods for safety assessment of support structures: the first is a stress assessment method based on traditional material mechanics combined with empirical calculations. This method has two main problems: first, for complex support structures, the stress calculation results may be seriously distorted, causing the assessment results to deviate from the actual situation; second, this method cannot obtain the stress distribution at every point in the structure, making it difficult to accurately guide the optimal design of the support structure, thereby greatly extending the iterative design cycle. The second method is a stress assessment method based on numerical simulation, which can effectively avoid the two disadvantages of the first method. With the continuous development of computer technology, the safety assessment of support structures has gradually shifted from the traditional material mechanics combined with empirical calculations to numerical simulation methods.

[0004] However, both methods are limited to basic mechanical calculations of supports, and do not provide comprehensive evaluation solutions based on the calculation results in combination with relevant standards. Summary of the Invention

[0005] In order to solve the problems existing in the background technology, the present invention proposes a safety verification and assessment method for plate and shell type pipeline supports used in the nuclear power field.

[0006] To address these issues, the present invention proposes a numerical verification method that integrates nuclear power industry standards. This method simulates the structural mechanical behavior of support components, from local to global perspectives. The calculated results are then combined with the structural assessment specifications for plate-shell support components to perform structural verification and achieve structural safety assessments for support components. Programming based on the numerical verification method presented in this patent can automate support component safety assessments in the nuclear power industry.

[0007] The support is a plate-shell pipe support used in the nuclear power field to support objects, such as scaffolding and brackets. The present invention mainly verifies the mechanical parameters of the support, evaluates the simulation algorithm results, and evaluates the mechanical structural safety of the support.

[0008] The method and technical solution adopted by the present invention are specifically:

[0009] The specific support structure safety verification and assessment method includes the following steps:

[0010] Step 1: Create a computer model of the support;

[0011] Step 2: Apply relevant loads and constraints according to the working conditions based on the computer mesh model of the support for subsequent simulation and evaluation;

[0012] Step 3: Simulate the computer model of the support component and then perform a combined load analysis based on the simulation results (i.e., the stress conditions of the support component when it is subjected to both static and seismic loads). Extract the stress component results of the shell element for each condition.

[0013] Step 4: Perform support structure verification for different support objects based on the shell element stress results extracted in step 3.

[0014] The step 1 is specifically as follows:

[0015] Based on the support component's design drawings or external modeling files, a 3D model of the support component is created in the computer. This model can be a vector model or a mesh model. Specifically, the main beam, baseplate, connectors, and reinforcements are modeled. The main body and other components, such as the connectors and baseplate, are modeled using plate and shell elements.

[0016] In addition, in a computer, the support structure is divided into a grid according to the established three-dimensional model to form a grid model, which is a triangular facet or a quadrilateral facet model for subsequent finite element structural mechanics simulation and dynamics simulation.

[0017] The step 2 specifically involves applying two types of loads, including static loads and dynamic loads, to the grid model of the support member simultaneously in a computer.

[0018] The static load includes:

[0019] Concentrated force load: acts on any local position of the main beam of the support, used to simulate the load on the support when it carries objects such as pipes;

[0020] Distributed force load: acts on the overall structure of the support, used to simulate the load of the support under the natural environment in windy and snowy weather;

[0021] Acceleration (usually gravity): acts on the three-dimensional model of the support to simulate the load on the support caused by the earth's gravity;

[0022] Thermal load: acts on the three-dimensional model of the support to simulate the load caused by thermal expansion of the support when working in a high-temperature environment;

[0023] The dynamic load includes a seismic response spectrum, which acts on the three-dimensional model of the support member to simulate the load caused by the support member in an earthquake environment.

[0024] In a specific implementation, constraints may be imposed on the substrate of the support member (the substrate is a structure connecting the main structure of the support member with the ground, usually a plate-shaped metal structure), that is, the substrate is fixed on the ground.

[0025] The three-dimensional model of the support member in the computer is divided into different parts of shell elements, beam elements, and three-dimensional elements. Different element types are usually determined and distinguished by setting different element type contents in the calculation file for each element type, which is a conventional technology.

[0026] In step 2, after the loads and constraints are introduced, the structural displacement under a certain load can be uniquely determined.

[0027] The step 3 is specifically as follows:

[0028] After the finite element simulation is completed, different simulation results are extracted for different scenarios and support objects, and the following extraction processes are performed:

[0029] S3A. If only static analysis or response spectrum analysis exists in the combined load case analysis type, the stress components of the shell elements in each geometric element are directly extracted and processed as follows:

[0030] For the primary support, select the position of the shell element in the support and perform the following judgment and extraction processing:

[0031] Extract local membrane stress, bending stress, expansion stress in secondary stress, and stress components of three primary principal stresses at the geometric discontinuity position of the shell element;

[0032] For the geometrically continuous positions of the shell elements, the stress components of the overall membrane stress are extracted;

[0033] For the secondary supports, the stress components of the overall membrane stress and bending stress close to the geometric discontinuity are directly extracted, and the stress components of the overall membrane stress and bending stress far away from the geometric discontinuity but with greater stress are extracted;

[0034] The position close to the geometric discontinuity refers to a position whose distance from the center of the geometric discontinuity is less than or equal to a preset distance threshold; the position far from the geometric discontinuity but subjected to greater force refers to a position whose distance from the center of the geometric discontinuity is greater than a preset distance threshold and whose force is greater than or equal to a preset mechanical threshold.

[0035] The primary support member refers to a support member used to support the primary equipment. The primary equipment generally refers to a component whose failure may cause leakage of radioactive materials in the reactor.

[0036] The secondary supports are used to support secondary equipment. Secondary equipment generally refers to equipment that supports other equipment in nuclear power plants that are not primary equipment. Failure of such equipment will not cause leakage of radioactive materials.

[0037] S3B. If both static analysis and response spectrum analysis are performed in the combined load case analysis, the absolute values of the stress component results of the static analysis and response spectrum analysis on each shell element are linearly superimposed and then extracted in the same manner as in S3A above.

[0038] The present invention only extracts and evaluates stress for shell elements, and avoids the stress maximum value being the stress concentration point.

[0039] The support analysis should include five types of working conditions: design working conditions, normal working conditions, disturbance working conditions, emergency working conditions, and accident working conditions.

[0040] In step 4, the verification requirements under five working conditions, namely design working condition, normal working condition, disturbance working condition, emergency working condition and accident working condition, are followed, and the evaluation of primary support components and secondary support components are differentiated:

[0041] (1) For primary support members:

[0042] 1) Design condition, the load consists of the maximum static load that the support can cause during normal operation, and the relevant load is applied to the model. Then, perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following:

[0043] 1A. Overall primary film stress strength limit:

[0044] Overall primary film stress intensity P m The stress tensor is obtained by linearly averaging the primary stress components generated by the design load in the thickness direction of the shell element's region of interest, and then performing TRESCA yield calculation on the stress tensor. The linear averaging is to divide the shell element's region of interest in the thickness direction into multiple layers, and the stress components of the multiple layers are sequentially increased or decreased along the force direction to form a linear relationship, thereby obtaining the stress tensor of each layer.

[0045] Set the overall primary film stress intensity P m The maximum allowable value is the basic allowable stress intensity value S at the design temperature. m :

[0046] P m ≤1.0S m

[0047] Among them, 1.0 is the limit value coefficient;

[0048] 1B. Overall primary film bending stress strength limit:

[0049] Overall primary film stress intensity P m The primary stress tensor is obtained by linearizing and averaging the primary stress components generated by the design load in the thickness direction of the shell element in the area of interest, and then performing TRESCA yield calculation on the primary stress tensor.

[0050] Bending stress intensity P b The bending stress tensor is obtained by linearizing and averaging the bending stress components generated by the design load in the thickness direction of the shell element in the area of interest, and then performing TRESCA yield calculation on the bending stress tensor;

[0051] The linearized averaging is to divide the region of interest of the shell element into multiple layers in the thickness direction, and the stress components of the multiple layers are sequentially increased or decreased along the force direction so as to form a linear relationship, thereby obtaining the stress tensor of each layer;

[0052] Set the overall primary membrane stress intensity plus bending stress intensity P m +P b The maximum allowable value is the basic allowable stress intensity value S at the design temperature. m 1.5 times:

[0053] P m +P b ≤1.5S m

[0054] Among them, 1.5 is the limit value coefficient;

[0055] 2) Normal working condition: The load consists of the static load that the support may be subjected to during normal operation. The relevant loads are applied to the model, and then steps 2 and 3 are performed to obtain the stress component results of the shell element. Then the following settings are made:

[0056] The stress component results obtained under the current conditions are judged according to the same formula in the design working condition processing. In addition, the overall primary membrane stress, bending stress, and secondary stress P e The total value of the total value is the maximum allowable value of the basic allowable stress intensity value S m 3 times:

[0057] P m +P b +P e ≤3.0S m

[0058] Among them, 3.0 is the limit value coefficient;

[0059] 3) Disturbance condition: The load consists of the static and dynamic loads that the support may be subjected to during normal operation. Perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following:

[0060] The stress component results obtained under the current conditions are judged according to the same formula used in the design and normal working conditions, and are required to meet the special stress limit at the same time. When the special stress limit conflicts with the design and normal working conditions, the special stress limit shall prevail.

[0061] 4) Emergency conditions: The load consists of the static and dynamic loads that the support receives in an emergency (such as a sudden fire or earthquake). Perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following:

[0062] The stress component results obtained under the current conditions are judged according to the same formula used in the design, normal and emergency conditions, except that the limit value coefficients are all set to 1.2 (the special stress limit coefficient remains unchanged);

[0063] 5) Accident conditions: The load consists of the static and dynamic loads on the support components when an accident occurs (such as a pipeline leak or a building collapse caused by an earthquake). Perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following:

[0064] Overall primary film stress intensity P m Satisfies the following formula:

[0065] P m ≤Min{S y , 0.7S u}

[0066] Local primary film stress intensity P L The limit satisfies the following formula:

[0067] P L ≤1.5Min{S y , 0.7S u}

[0068] The total or local primary membrane stress intensity plus bending stress intensity limit satisfies the following formula:

[0069] P m +P b ≤1.5Min{S y , 0.7S u}

[0070] P L+P b ≤1.5Min{S y , 0.7S u}

[0071] Among them, S y Indicates yield strength, S u Indicates tensile strength;

[0072] 6) Special stress limit: the algebraic sum of the three primary principal stresses shall not exceed the basic allowable stress intensity value S at the design temperature. m 4 times:

[0073] σ1+σ2+σ3≤4.0S m

[0074] Among them, σ1, σ2, and σ3 represent the three primary principal stresses respectively;

[0075] (2) For secondary supports:

[0076] The verification of secondary support parts is basically the same as that of primary support parts. In accident conditions, the judgment and evaluation of local primary membrane stress strength limit and special stress limit are not performed.

[0077] The stress of the present invention is divided into primary stress and secondary stress. Primary stress refers to stress that is only affected by external forces, and secondary stress refers to stress that is affected by temperature and external forces.

[0078] Membrane stress refers to the stress that is uniformly distributed through the thickness of the section in the shell element.

[0079] The beneficial effects and advantages of the present invention are:

[0080] The present invention is an automated verification solution for nuclear-grade plate and shell supports, enabling practitioners to design related structures more efficiently. It provides a verification solution for nuclear-grade supports and a corresponding verification algorithm based on the solution.

[0081] The present invention meets the verification requirements of overall stress and local stress, and increases the comprehensiveness and accuracy of the verification.

[0082] The verification method provided by the present invention can solve the current situation in the industry where there is a lack of a unified verification process.

[0083] The present invention provides a complete verification process, and practitioners can quickly perform verification according to the process to improve the design efficiency of nuclear-grade supports.

[0084] The present invention provides a set of automated calibration processes, which can avoid inaccurate calibration due to lack of experience of operators and improve the calibration reliability of nuclear-grade support components. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 This is a flow chart of the support structure safety assessment method based on mechanical numerical simulation;

[0086] Figure 2 It is a structural diagram of the bracket in a specific embodiment. DETAILED DESCRIPTION

[0087] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0088] In order to explain the present invention more clearly, a specific embodiment is provided below to illustrate the specific implementation method of the present invention.

[0089] like Figure 1 As shown, the specific embodiment of the support structure safety verification and evaluation of the present invention is as follows:

[0090] Step 1: Create a computer model of the support;

[0091] Based on the support component's design drawings or external modeling files, a 3D model of the support component is created in the computer. This model can be either a vector model or a mesh model. Specifically, the main beam, baseplate, connectors, and reinforcements are modeled. The main body and other components, such as connectors and baseplates, are modeled using plate and shell elements.

[0092] In addition, in the computer, the support structure is divided into a grid according to the established three-dimensional model to form a grid model, which is a model of triangular facets or quadrilateral facets for subsequent finite element structural mechanics simulation and dynamics simulation.

[0093] In the specific implementation, according to the design drawings of the pipe support of a nuclear power plant, a three-dimensional geometric model of the support is established. Based on these models, mesh division is performed, and finally a mesh model for calculation is obtained (see Figure 2 ).

[0094] In step 1, the main support model is built based on the design drawings. The shell elements in the model take into account the effects of transverse shear deformation based on Kirchhoff's thin plate theory. Kirchhoff's thin plate is a model for small deflection bending of isotropic thin plates.

[0095] Step 2: Apply relevant loads and constraints according to the working conditions based on the computer mesh model of the support for subsequent simulation and evaluation.

[0096] Specifically, in the computer, two types of loads are applied simultaneously to the mesh model of the support, including static loads and dynamic loads. The loads on the support structure are as follows (Table 5-8):

[0097] Table 5: Acceleration loads

[0098]

[0099] Table 6: SL-1 / Story Response Spectrum in the X-Direction (20.0% Damping Ratio)

[0100]

[0101]

[0102] Table 7: SL-1 / Story Response Spectrum in the Y-Direction (20.0% Damping Ratio)

[0103]

[0104] Table 8: SL-1 / Story Response Spectrum in the Z-Direction (20.0% Damping Ratio)

[0105]

[0106] Step 3: After applying the loads in step 2 (load data in Table 5-8) to the support simultaneously, simulate the computer model of the support. Then, perform a combined working condition analysis based on the simulation results (i.e., the stress conditions of the support when it is subjected to static loads and seismic loads at the same time), and extract the stress component results of the shell unit for different conditions.

[0107] After the finite element simulation is completed, different simulation results are extracted for different scenarios and support objects. After the combined working condition analysis is completed, the following extraction processing is performed:

[0108] S3A. If only static analysis or response spectrum analysis exists in the combined load case analysis type, the stress components of the shell elements in each geometric element are directly extracted and processed as follows:

[0109] For the primary support, select the position of the shell element in the support and perform the following judgment and extraction processing:

[0110] For the geometric discontinuity of the shell element, such as the geometric discontinuity around the hole on the shell element, extract its local membrane stress (P L ), bending stress (P b ) and the expansion stress in the secondary stress (P e ), the sum of the stress components of the three primary principal stresses (σ1+σ2+σ3);

[0111] For the geometrically continuous position of the shell element, for example, the geometrically continuous position is the selected position where there is no sudden change in geometry or geometric discontinuity (such as a hole), then the overall membrane stress (P m) stress components rather than local membrane stresses;

[0112] The stress classification of the primary support members of the plate and shell structure is shown in the following table:

[0113] Table 1: Classification of stress of primary support

[0114]

[0115] For secondary supports, the local membrane stress (P L ) and bending stress (P b ) and extract the stress components of the overall membrane stress and bending stress at locations far away from geometric discontinuities but with greater stress;

[0116] A position close to a geometric discontinuity refers to a position whose distance from the center of the geometric discontinuity is less than or equal to a preset distance threshold; a position far from a geometric discontinuity but subjected to greater force refers to a position whose distance from the center of the geometric discontinuity is greater than a preset distance threshold and whose force is greater than or equal to a preset mechanical threshold.

[0117] The stress classification of the secondary support members of the plate and shell structure is shown in the following table:

[0118] Table 2: Classification of stress of secondary supports

[0119]

[0120] The primary support member refers to a support member used to support the primary equipment. The primary equipment generally refers to a component whose failure may cause leakage of radioactive materials in the reactor.

[0121] The secondary supports are used to support secondary equipment. Secondary equipment generally refers to equipment that supports other equipment in nuclear power plants that are not primary equipment. Failure of such equipment will not cause leakage of radioactive materials.

[0122] S3B. If both static analysis and response spectrum analysis are performed in the combined load case analysis, the absolute values of the stress component results from the static analysis and response spectrum analysis on each shell element are linearly superimposed and then extracted in the same manner as in S3A above.

[0123] The present invention only extracts and evaluates stress for shell elements, and avoids the stress maximum value being the stress concentration point.

[0124] In step 3, after completing the support component combination analysis, data extraction is performed.

[0125] The main structure of the support adopts shell elements to extract the overall or local membrane stress (P m / P L ), bending stress strength (Pb ), and according to different working conditions, it is also necessary to extract the secondary stress (P e ).

[0126] Step 4: Perform support structure verification for different support objects based on the shell element stress results extracted in Step 3. Support analysis should include five types of conditions: design conditions, normal conditions, disturbance conditions, emergency conditions, and accident conditions.

[0127] In step 4, the verification requirements under five working conditions, namely design working condition, normal working condition, disturbance working condition, emergency working condition and accident working condition, are followed, and the evaluation of primary and secondary supporting parts is distinguished:

[0128] (1) For primary support members:

[0129] 1) Design condition, where the load consists of the maximum static load (excluding thermal load) that the support can cause during normal operation. Apply the relevant loads to the model, then perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following:

[0130] 1A. Overall primary film stress strength limit:

[0131] Overall primary membrane stress P m The stress tensor is obtained by linearizing and averaging the primary stress components generated by the design load in the thickness direction of the shell element's area of interest, and then performing TRESCA yield calculation on the stress tensor. The linearized averaging is to divide the shell element's area of interest in the thickness direction into multiple layers, and the stress components of the multiple layers are sequentially increased or decreased along the force direction to form a linear relationship, thereby obtaining the stress tensor of each layer.

[0132] Set the overall primary membrane stress P m The maximum allowable value is the basic allowable stress intensity value S m :

[0133] P m ≤1.0S m

[0134] Among them, 1.0 is the limit value coefficient;

[0135] 1B. Primary film bending stress strength limit:

[0136] Overall primary membrane stress P m The primary stress tensor is obtained by linearizing and averaging the primary stress components generated by the design load in the thickness direction of the shell element in the area of interest, and then performing TRESCA yield calculation on the primary stress tensor.

[0137] Bending stress P bThe bending stress tensor is obtained by linearizing and averaging the bending stress components generated by the design load in the thickness direction of the shell element in the area of interest, and then performing TRESCA yield calculation on the bending stress tensor;

[0138] The linearized averaging method is to divide the region of interest of the shell element into multiple layers in the thickness direction. The stress components of the multiple layers are processed in sequence along the force direction to increase or decrease in a linear relationship, thereby obtaining the stress tensor of each layer.

[0139] Set the overall primary membrane stress plus bending stress P m +P b The maximum allowable value is the basic allowable stress intensity value S at the design temperature. m 1.5 times (S m is the basic allowable stress intensity value):

[0140] P m +P b ≤1.5S m

[0141] Among them, 1.5 is the limit value coefficient;

[0142] 2) Normal working condition, the load consists of the static load that the support may be subjected to during normal operation, and the relevant load is applied to the model. Then, steps 2 and 3 are performed to obtain the stress component results of the shell element, and then the following settings are made:

[0143] The stress component results obtained under the current conditions are judged according to the same formula as in the design condition processing. In addition, the overall primary membrane stress, bending stress, secondary stress (P e The maximum allowable value of the total value is the basic allowable stress intensity value S m 3 times:

[0144] P m +P b +P e ≤3.0S m

[0145] Among them, 3.0 is the limit value coefficient;

[0146] 3) For the disturbance condition, the load is obtained by performing steps 2 and 3 under the static and dynamic loads that the support may be subjected to during normal operation to obtain the stress component results of the shell element, and then the following settings are made:

[0147] The stress component results obtained under the current conditions are judged according to the same formulas in the design and normal working conditions, and are required to meet the special stress limit at the same time. When the special stress limit conflicts with the design and normal working conditions, the special stress limit shall prevail.

[0148] 4) Emergency conditions: The load is the static load and dynamic load that the support receives in an emergency (such as a sudden fire, sudden earthquake, etc.). Steps 2 and 3 are performed to obtain the stress component results of the shell element, and then the following settings are made:

[0149] The stress component results obtained under the current conditions are judged according to the same formula as in the design working condition, normal working condition, and disturbance working condition, but the limit value coefficient is set to 1.2 times the original value (the special stress limit coefficient remains unchanged);

[0150] 5) Accident conditions: The load is the static and dynamic loads that the support is subjected to when an accident occurs (such as a pipeline leak, a building collapse caused by an earthquake, etc.). Steps 2 and 3 are performed to obtain the stress component results of the shell element, and then the following settings are made:

[0151] Overall primary film stress intensity P m Satisfies the following formula:

[0152] P m ≤Min{S y , 0.7S u}

[0153] Local primary film stress intensity P L The limit satisfies the following formula:

[0154] P L ≤1.5Min{S y , 0.7S u}

[0155] The total or local primary membrane stress intensity plus bending stress intensity limit satisfies the following formula:

[0156] P m +P b ≤1.5Min{S y , 0.7S u}

[0157] P L +P b ≤1.5Min{S y , 0.7S u}

[0158] 6) Special stress limit: the algebraic sum of the three primary principal stresses shall not exceed the membrane stress limit S at the design temperature. m 4 times:

[0159] σ1+σ2+σ3≤4.0S m

[0160] Among them, S y Indicates yield strength, Su Indicates tensile strength.

[0161] For the primary support assessment, the stress assessment method is shown in the following table:

[0162] Table 3: Primary support stress assessment

[0163]

[0164] (2) For secondary supports:

[0165] The verification of secondary supports is basically the same as that of primary supports, but there is no need to consider local membrane stress and special stress limits, that is, local primary membrane stress strength limits are not carried out in accident conditions, and judgment and evaluation of special stress limits are not performed.

[0166] That is, the accident conditions are only:

[0167] Overall primary film stress intensity P m Satisfies the following formula:

[0168] P m ≤Min{S y , 0.7S u}

[0169] The overall or local primary film bending stress strength limit satisfies the following formula:

[0170] P m +P b ≤1.5Min{S y , 0.7S u}

[0171] For secondary support assessment, the stress assessment method is shown in the following table:

[0172] Table 4: Secondary support stress assessment

[0173]

[0174] The bracket of the final embodiment is a secondary device. The shell model adopts the evaluation method of Table 2 and Table 4. In order to avoid stress concentration caused by analysis, the calibration position can be selected according to experience. The following Table 9 shows the calibration results of the shell structure based on RCC-M. The calculated stress values are P m and P m +P b :

[0175] Table 9 Stress evaluation results

[0176]

[0177] From this implementation, it can be seen that the calculated stress values of this support under the five working conditions are all less than the stress limit. It can be considered that this support meets the verification requirements.

[0178] The above specific embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

[0179] The above description is only a preferred embodiment of the present invention. Therefore, any equivalent changes or modifications made according to the structure, characteristics and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. A safety verification and assessment method for shell and plate piping supports used in the nuclear power industry, characterized by: The method comprises the following steps: Step 1: Create a computer model of the support; Step 2: Apply relevant loads and constraints according to the working conditions based on the computer model of the support for subsequent simulation and evaluation; Step 3: Simulate the computer model of the support, then perform a combined working condition analysis based on the simulation results, and extract the stress component results of the shell element for different situations; Step 4: Perform support structure verification for different support objects based on the shell element stress results extracted in step 3.

2. A safety verification and assessment method for shell and plate type piping supports used in the nuclear power field according to claim 1, characterized in that: The step 1 specifically includes: establishing a three-dimensional model for the support member in a computer, and dividing the established three-dimensional model into a grid model in the computer.

3. The safety verification and assessment method for shell and plate type pipeline supports used in the nuclear power field according to claim 1, characterized in that: The step 2 specifically involves simultaneously applying two types of loads to the grid model of the support, including static loads and dynamic loads.

4. A safety verification and assessment method for shell and plate type piping supports used in the nuclear power field according to claim 3, characterized in that: The static load includes: Concentrated force load: acts on any local position of the main beam of the support, used to simulate the load on the support when it carries objects such as pipes; Distributed force load: acts on the overall structure of the support, used to simulate the load of the support under the natural environment in windy and snowy weather; Acceleration: Acting on the three-dimensional model of the support, used to simulate the load on the support caused by the earth's gravity; Thermal load: acts on the three-dimensional model of the support to simulate the load caused by thermal expansion of the support when working in a high-temperature environment; The dynamic load includes a seismic response spectrum, which acts on the three-dimensional model of the support member to simulate the load caused by the support member in an earthquake environment.

5. The safety verification and assessment method for shell and plate type piping supports used in the nuclear power field according to claim 1, characterized in that: The three-dimensional model of the support member in the computer is divided into shell units, beam units and three-dimensional units.

6. The safety verification and assessment method for shell and plate type piping supports used in the nuclear power field according to claim 1, characterized in that: The step 3 is specifically as follows: After the finite element simulation is completed, different simulation results are extracted for different scenarios and support objects, and the following extraction processes are performed: S3A. If only static analysis or response spectrum analysis exists in the combined load case analysis type, the stress components of the shell elements in each geometric element are directly extracted and processed as follows: For the primary support, select the position of the shell element in the support and perform the following judgment and extraction processing: Extract local membrane stress, bending stress, expansion stress in secondary stress, and stress components of three primary principal stresses at the geometric discontinuity position of the shell element; For the geometrically continuous positions of the shell elements, the stress components of the overall membrane stress are extracted; For the secondary supports, the stress components of the overall membrane stress and bending stress close to the geometric discontinuity are directly extracted, and the stress components of the overall membrane stress and bending stress far away from the geometric discontinuity but with greater stress are extracted; S3B. If both static analysis and response spectrum analysis are performed in the combined load case analysis, the absolute values of the stress component results of the static analysis and response spectrum analysis on each shell element are linearly superimposed and then extracted in the same manner as in S3A above.

7. The safety verification and assessment method for shell and plate type piping supports used in the nuclear power field according to claim 1, characterized in that: In step 4, the verification requirements under five working conditions, namely design working condition, normal working condition, disturbance working condition, emergency working condition and accident working condition, are followed, and the evaluation of primary support components and secondary support components are differentiated: (1) For primary support members: 1) Design condition, the load consists of the maximum static load that the support can cause during normal operation, and the load is applied to the model. Then, perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following: 1A. Overall primary film stress strength limit: Overall primary film stress intensity P m The stress tensor is obtained by linearly averaging the primary stress components generated by the design load in the thickness direction of the shell element's region of interest, and then performing TRESCA yield calculation on the stress tensor. The linear averaging is to divide the shell element's region of interest in the thickness direction into multiple layers, and the stress components of the multiple layers are sequentially increased or decreased along the force direction to form a linear relationship, thereby obtaining the stress tensor of each layer. Set the overall primary film stress intensity P m The maximum allowable value is the basic allowable stress intensity value S at the design temperature. m : P m ≤1.0S m Among them, 1.0 is the limit value coefficient; 1B. Overall primary film bending stress strength limit: Overall primary film stress intensity P m The primary stress tensor is obtained by linearizing and averaging the primary stress components generated by the design load in the thickness direction of the shell element in the area of interest, and then performing TRESCA yield calculation on the primary stress tensor. Bending stress intensity P b The bending stress tensor is obtained by linearizing and averaging the bending stress components generated by the design load in the thickness direction of the shell element in the area of interest, and then performing TRESCA yield calculation on the bending stress tensor; The linearized averaging is to divide the region of interest of the shell element into multiple layers in the thickness direction, and the stress components of the multiple layers are sequentially increased or decreased along the force direction so as to form a linear relationship, thereby obtaining the stress tensor of each layer; Set the overall primary membrane stress intensity plus bending stress intensity P m +P b The maximum allowable value is the basic allowable stress intensity value S at the design temperature. m 1.5 times: P m +P b ≤1.5S m Among them, 1.5 is the limit value coefficient; 2) Normal working condition: The load consists of the static load that the support may be subjected to during normal operation. The load is applied to the model, and then steps 2 and 3 are performed to obtain the stress component results of the shell element. Then the following settings are made: The stress component results obtained under the current conditions are judged according to the same formula in the design working condition processing. In addition, the overall primary membrane stress, bending stress, and secondary stress P e The total value of the total value is the maximum allowable value of the basic allowable stress intensity value S m 3 times: P m +P b +P e ≤3.0S m Among them, 3.0 is the limit value coefficient; 3) Disturbance condition: The load consists of the static and dynamic loads that the support may be subjected to during normal operation. Perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following: The stress component results obtained under the current conditions are judged according to the same formula used in the design and normal working conditions, and are required to meet the special stress limit at the same time. When the special stress limit conflicts with the design and normal working conditions, the special stress limit shall prevail. 4) Emergency conditions: The load consists of the static and dynamic loads on the support in an emergency. Perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following: The stress component results obtained under the current conditions are judged according to the same formula used in the design working condition, normal working condition and emergency working condition processing, but the limit value coefficients except for the special stress limit coefficient are all set to 1.2 times; 5) Accident condition: The load consists of the static and dynamic loads on the support when an accident occurs. Perform steps 2 and 3 to obtain the stress component results of the shell element, and then set the following: Overall primary film stress intensity P m Satisfies the following formula: P m ≤Min{S y ,0.7S u } Local primary film stress intensity P L The limit satisfies the following formula: P L ≤1.5Min{S y ,0.7S u } The total or local primary membrane stress intensity plus bending stress intensity limit satisfies the following formula: P m +P b ≤1.5Min{S y ,0.7S u } P L +P b ≤1.5Min{S y ,0.7S u } Among them, S y Indicates yield strength, S u Indicates tensile strength; 6) Special stress limit: the algebraic sum of the three primary principal stresses shall not exceed the basic allowable stress intensity value S at the design temperature. m 4 times: σ1+σ2+σ3≤4.0S m Among them, σ1, σ2, and σ3 represent the three primary principal stresses respectively; (2) For secondary supports: The verification of secondary support parts is basically the same as that of primary support parts. In accident conditions, the judgment and evaluation of local primary membrane stress strength limit and special stress limit are not performed.

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