Method and device for calculating ultimate bearing capacity of unbonded prestressed containment

Abstract

The invention discloses a calculation method, an evaluation method and a device for ultimate bearing capacity of an unbonded prestressed containment vessel. The calculation method comprises the following steps: S1, acquiring first ultimate bearing capacity of a bonded prestressed containment vessel; s2, judging whether a first stress variable of a prestressed steel beam in the bonded prestressed containment vessel is the same as a second stress variable of a prestressed steel beam in the unbonded prestressed containment vessel or not under the condition that the bonded prestressed containment vessel applies a preset load corresponding to the first ultimate bearing capacity; if yes, compensating the first prestress of the prestressed steel beam in the bonded prestressed containment vessel to obtain a corrected second prestress of the prestressed steel beam in the unbonded prestressed containment vessel so as to calculate the ultimate bearing capacity of the unbonded prestressed containment vessel. According to the method, the ultimate bearing capacity of the unbonded prestressed containment can be calculated more accurately. Therefore, the subsequent containment can be evaluated more accurately to ensure the safe operation of the nuclear power station.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear power technology, and in particular relates to a calculation method, an evaluation method and a device for the ultimate bearing capacity of an unbonded prestressed containment. Background Art

[0002] The prestressed containment shell includes concrete and prestressed steel strands. Among them, the prestressed steel strands can be used to provide prestress to resist accident pressure, without considering their bearing capacity contribution. Concrete can be used to bear the loads generated by the prestressed steel strands and the stress changes under the load combination. The prestressed system composed of concrete and prestressed steel strands can make the prestressed containment shell have better crack resistance and durability while bearing loads.

[0003] Prestressed containment can be divided into bonded prestressed system and unbonded prestressed system according to the type of prestressed system. Because in bonded prestressed system, after the duct is grouted, the prestressed steel strands and the containment become a deformed and coordinated whole, and cannot be repaired after being damaged. In order to make the prestressed system of the containment repairable (re-tensioning or replacing) after being damaged, an unbonded prestressed system with a relatively low friction coefficient is used, which can reduce the amount of prestressed materials and save construction time.

[0004] By simulating the prestress of the prestressed steel strands in the unbonded prestressed containment, the ultimate bearing capacity of the unbonded prestressed containment is calculated. The calculated ultimate bearing capacity of the unbonded prestressed containment can be used to evaluate the unbonded prestressed containment to ensure the safe operation of the nuclear power plant.

[0005] However, in the prior art, the prestress of the prestressed steel bundles in the unbonded prestressed containment is replaced by the prestress of the prestressed steel bundles in the bonded prestressed containment, which results in a low accuracy of the prestress of the prestressed steel bundles in the simulated unbonded prestressed containment, reduces the accuracy of the calculation of the ultimate bearing capacity of the unbonded prestressed containment, and affects the evaluation effect of the unbonded prestressed containment. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a calculation method, an evaluation method and a device for the ultimate bearing capacity of an unbonded prestressed containment shell in view of the above-mentioned deficiencies in the prior art. By using the calculation method, the prestress of the prestressed steel strands in the unbonded prestressed containment shell can be accurately simulated, thereby effectively improving the accuracy of the calculation of the ultimate bearing capacity of the unbonded prestressed containment shell and improving the accuracy of the evaluation of the unbonded prestressed containment shell.

[0007] In a first aspect, the present invention provides a method for calculating the ultimate bearing capacity of an unbonded prestressed containment shell, comprising:

[0008] S1. Obtaining the first ultimate bearing capacity of the bonded prestressed containment;

[0009] S2. Determine whether the first stress variable of the prestressed steel strand in the bonded prestressed containment shell and the second stress variable of the prestressed steel strand in the unbonded prestressed containment shell are equal when a preset load corresponding to the first ultimate bearing capacity is applied to the bonded prestressed containment shell.

[0010] same:

[0011] If the two are not the same, the first prestress of the prestressed steel strands in the bonded prestressed containment is compensated to obtain the corrected second prestress of the prestressed steel strands in the unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment.

[0012] In some embodiments, step S2 further includes:

[0013] If the two are the same, the first ultimate bearing capacity of the bonded prestressed containment shell is directly determined as the ultimate bearing capacity of the unbonded prestressed containment shell.

[0014] In some embodiments, the containment vessel comprises a steel lining, steel reinforcement,

[0015] In step S1, obtaining the first ultimate bearing capacity of the bonded prestressed containment is to determine the first ultimate bearing capacity of the bonded prestressed containment according to the failure criterion, which specifically includes:

[0016] S11. Gradually apply a preset load to the bonded prestressed containment;

[0017] S12. When the maximum plastic strain of the steel lining reaches a first preset threshold value, the preset load applied to the bonded prestressed containment shell at this time is determined as the first ultimate bearing capacity.

[0018] In some embodiments, the determining whether a first stress variable of a prestressed steel bundle in the bonded prestressed containment shell is the same as a second stress variable of a prestressed steel bundle in the unbonded prestressed containment shell when a preset load corresponding to a first ultimate bearing capacity is applied to the bonded prestressed containment shell specifically includes:

[0019] S21. Determine whether the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is equal;

[0020] S22. If they are equal, then determine that the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is the same as the second stress variable of each finite element unit of the prestressed steel strand in the unbonded prestressed containment;

[0021] S23. If they are not equal, it is determined that the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is different from the second stress variable of each finite element unit of the prestressed steel strand in the unbonded prestressed containment.

[0022] In some embodiments, compensating the first prestress of the prestressed steel strands in the bonded prestressed containment to obtain a modified second prestress of the prestressed steel strands in the unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment specifically includes:

[0023] S24. The deformation of each steel strand in the unbonded prestressed steel strand is set to be uniform, so as to compensate for the first prestress of the bonded prestressed steel strand and obtain the second prestress of the unbonded prestressed steel strand;

[0024] S25. Calculate the ultimate bearing capacity of the unbonded prestressed containment shell based on the second prestress of the unbonded prestressed steel tendons.

[0025] In some embodiments, step S24 specifically includes:

[0026] S241. Obtaining a first total deformation of the prestressed steel strands in the bonded prestressed containment;

[0027] S242. Determine a second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment according to the first total deformation;

[0028] S243. Determine the compensation stress of each finite element unit according to the second average stress variable of each steel strand and the stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment;

[0029] S244. Determine the second prestress of the prestressed steel strands in the unbonded prestressed containment shell based on the compensating stress of each finite element unit and the first prestress of the bonded prestressed steel strands.

[0030] In some embodiments, step S241 specifically includes:

[0031] According to the following formula (1), the first total deformation ΔL of the prestressed steel tendons in the bonded prestressed containment is calculated:

[0032]

[0033] Wherein, ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa); s is the distance between the finite element unit and the starting point of the steel strand (m); Δσ 有粘结is the stress variable of the finite element unit of the prestressed steel strand in the bonded prestressed containment under the preset load (MPa);

[0034] Step S242 specifically includes:

[0035] According to the following formula (2), the second average stress variable Δσ of each steel strand in the prestressed steel strand in the unbonded prestressed containment is calculated: PE :

[0036] Δσ PE =ΔL / L×E s (2)

[0037] Among them, Δσ PE is the second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment (MPa), ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa);

[0038] Step S243 specifically includes:

[0039] The compensation stress of each finite element is calculated according to the following formula (3):

[0040] σ 补偿 =Δσ PE -Δσ 有粘结 (3)

[0041] Among them, σ 补偿 is the compensation stress (MPa) of each finite element.

[0042] In some embodiments, before step S1, the method further includes:

[0043] A finite element model of a bonded prestressed containment shell is established; the finite element model includes concrete, steel lining, steel bars and prestressed steel strands.

[0044] In a second aspect, the present invention further provides a safety assessment method for a nuclear power plant, comprising:

[0045] Determine the ultimate bearing capacity of the unbonded prestressed containment according to the calculation method of the ultimate bearing capacity of the unbonded prestressed containment as described in any one of the above items;

[0046] According to the ultimate bearing capacity of the unbonded prestressed containment, the safety of the nuclear power plant is evaluated to ensure the safe operation of the nuclear power plant.

[0047] In a third aspect, the present invention further provides a device for calculating the ultimate bearing capacity of an unbonded prestressed containment shell, the device comprising:

[0048] An acquisition module, configured to acquire a first ultimate bearing capacity of a bonded prestressed containment shell;

[0049] The processing module is connected to the acquisition module and is configured to determine whether a first stress variable of a prestressed steel bundle in the bonded prestressed containment is the same as a second stress variable of a prestressed steel bundle in the unbonded prestressed containment when a preset load corresponding to a first ultimate bearing capacity is applied to the bonded prestressed containment:

[0050] If the two are not the same, the first prestress of the prestressed steel strands in the bonded prestressed containment is compensated to obtain the corrected second prestress of the prestressed steel strands in the unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment.

[0051] In some embodiments, the processing module 12 further includes:

[0052] an obtaining unit, connected to the first processing unit, for setting the deformation of each steel strand in the unbonded prestressed steel strand to be uniform, so as to compensate the first prestress of the bonded prestressed steel strand and obtain the second prestress of the unbonded prestressed steel strand;

[0053] The calculation unit is connected with the obtaining unit and is used for calculating the ultimate bearing capacity of the unbonded prestressed containment shell according to the second prestress of the unbonded prestressed steel tendons.

[0054] In some embodiments, obtaining the unit comprises:

[0055] A first acquisition subunit is used to obtain a first total deformation of the prestressed steel strands in the bonded prestressed containment shell;

[0056] A first determining subunit, connected to the first acquiring subunit, is used to determine a second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment shell according to the first total deformation;

[0057] A second determining subunit, connected to the first determining subunit, is used to determine the compensation stress of each finite element unit according to the second average stress variable of each steel strand and the stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment;

[0058] The third determining subunit is connected to the second determining subunit and is used to determine the second prestress of the prestressed steel strands in the unbonded prestressed containment shell according to the compensation stress of each finite element unit and the first prestress of the bonded prestressed steel strands.

[0059] In some embodiments, the first acquisition subunit is further used to calculate the first total deformation ΔL of the prestressed steel strands in the bonded prestressed containment shell according to the following formula (1):

[0060]

[0061] Wherein, ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa); s is the distance between the finite element unit and the starting point of the steel strand (m); Δσ 有粘结 is the stress variable of the finite element unit of the prestressed steel strand in the bonded prestressed containment under the preset load (MPa);

[0062] The first determination subunit is also used to calculate the second average stress variable Δσ of each steel strand in the prestressed steel strand in the unbonded prestressed containment according to the following formula (2): PE :

[0063] Δσ PE =ΔL / L×E s (2)

[0064] Among them, Δσ PE is the second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment (MPa), ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa);

[0065] The second determination subunit is also used to calculate the compensation stress of each finite element unit according to the following formula (3):

[0066] σ 补偿 =Δσ PE -Δσ 有粘结 (3)

[0067] Among them, σ 补偿 is the compensation stress (MPa) of each finite element.

[0068] The method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell of the present invention obtains the first ultimate bearing capacity of the bonded prestressed containment shell, determines whether the first stress variable of the prestressed steel bundle in the bonded prestressed containment shell is the same as the second stress variable of the prestressed steel bundle in the unbonded prestressed containment shell, and corrects the second prestress of the prestressed steel bundle in the unbonded prestressed containment shell. Because the second prestress of the prestressed steel bundle in the unbonded prestressed containment shell compensates for the uncoordinated deformation of the unbonded prestressed steel bundle and concrete, the prestress of the prestressed steel bundle in the unbonded prestressed containment shell can be accurately simulated, effectively improving the accuracy of the calculation of the ultimate bearing capacity of the unbonded prestressed containment shell, and improving the evaluation effect of the unbonded prestressed containment shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 A flow chart of a method for calculating the ultimate bearing capacity of an unbonded prestressed containment shell provided in an embodiment of the present invention;

[0070] Figure 2 A flowchart of an application example of a method for calculating the ultimate bearing capacity of an unbonded prestressed containment shell provided in an embodiment of the present invention;

[0071] Figure 3 A schematic structural diagram of a concrete non-bonded prestressed containment shell provided by an embodiment of the present invention;

[0072] Figure 4 A schematic structural diagram of a steel lining of an unbonded prestressed containment shell provided in an embodiment of the present invention;

[0073] Figure 5 A schematic diagram of the structure of a steel bar of an unbonded prestressed containment shell provided by an embodiment of the present invention;

[0074] Figure 6 A schematic structural diagram of a prestressed steel bundle of an unbonded prestressed containment shell provided in an embodiment of the present invention;

[0075] Figure 7 A structural diagram of a device for calculating the ultimate bearing capacity of an unbonded prestressed containment vessel provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0076] In order to make those skilled in the art better understand the technical scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only intended to explain the application, rather than to limit the application. For those skilled in the art, the application can be implemented when some details in these specific details are not needed. The following description of the embodiments is only for providing a better understanding of the application by illustrating the examples of the application.

[0077] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0078] In the related art, the simulation of unbonded prestressed steel strands cannot be realized in ANSYS software. The calculation of the ultimate bearing capacity of the unbonded prestressed containment is approximately replaced by the ultimate bearing capacity of the bonded prestressed containment. However, in the process of calculating the ultimate bearing capacity of the unbonded prestressed containment, the prestress of the prestressed steel strands in the bonded prestressed containment is used to replace the prestress of the prestressed steel strands in the unbonded prestressed containment, because for the bonded prestressed containment, its prestressed steel strands and concrete deform in coordination; while for the unbonded prestressed containment, the prestressed steel strands are constrained in the direction perpendicular to the length of the prestressed steel strands after the concrete is poured, but they can slide along the length direction, which is not coordinated with the deformation of the concrete. Therefore, the prestress of the prestressed steel strands in the bonded prestressed containment is used to replace the prestress of the prestressed steel strands in the unbonded prestressed containment, resulting in a low accuracy of the prestress of the prestressed steel strands in the simulated unbonded prestressed containment.

[0079] In addition, due to the complex structure of the unbonded prestressed containment, the many types of prestressed steel strands, and the continuous adjustment of their directions when bypassing the penetration parts, the length directions of most of the prestressed steel strands do not always coincide with a certain coordinate direction of the overall Cartesian coordinate system. The finite element analysis software in the prior art is mostly based on the overall Cartesian coordinate system for modeling and calculation, which makes it impossible to directly simulate the unbonded prestressed steel strands with complex spatial distribution.

[0080] The inventors have found that the first ultimate bearing capacity is obtained by first conducting an analysis based on the bonded prestressed containment, and then setting the stress variables of each finite element unit of the prestressed steel bundle in the unbonded prestressed containment to be the same, and correcting the prestress of the prestressed steel bundle in the bonded prestressed containment to obtain the prestress of the prestressed steel bundle in the unbonded prestressed containment. In this way, the prestress of the prestressed steel bundle in the unbonded prestressed containment can be accurately simulated, making the ultimate bearing capacity calculation of the unbonded prestressed containment more accurate.

[0081] Based on this, in order to solve the problems of the prior art, the present invention proposes a method and device for calculating the ultimate bearing capacity of an unbonded prestressed containment, which can accurately simulate the prestress of the prestressed steel strands in the unbonded prestressed containment, effectively improve the accuracy of the calculation of the ultimate bearing capacity of the unbonded prestressed containment, and improve the evaluation effect of the unbonded prestressed containment.

[0082] Embodiment 1:

[0083] like Figure 1 As shown, this embodiment provides a method for calculating the ultimate bearing capacity of an unbonded prestressed containment, which is mainly used in the design of a containment of a nuclear power system, and includes steps S1 to S2:

[0084] Step S1. Obtaining the first ultimate bearing capacity of the bonded prestressed containment shell.

[0085] Here, the bonded prestressed containment refers to a containment in which the prestressed steel strands and concrete deform in coordination. The first ultimate bearing capacity represents the maximum load that the bonded prestressed containment can withstand before reaching its failure state. It can be understood that once the external load of the bonded prestressed containment exceeds the first ultimate bearing capacity, the bonded prestressed containment will be irreversibly damaged or lose its function.

[0086] In some embodiments, the first ultimate bearing capacity is related to the internal pressure of the containment vessel. For example, for an internal pressure of typically 0.3 MPa to 0.5 MPa, the ultimate bearing capacity may be as high as 1.5 times or more of the design value.

[0087] During implementation, the first ultimate bearing capacity of the bonded prestressed containment can be obtained by finite element analysis. For example, a three-dimensional model of the containment is established using finite element software (such as ANSYS, ABAQUS, etc.) to perform nonlinear analysis. Nonlinear analysis includes analyzing the nonlinear behavior (such as plastic deformation) and geometric nonlinearity (such as large deformation) of the containment material.

[0088] Step S2. Determine whether the first stress variable of the prestressed steel strand in the bonded prestressed containment is the same as the second stress variable of the prestressed steel strand in the unbonded prestressed containment when a preset load corresponding to the first ultimate bearing capacity is applied to the bonded prestressed containment:

[0089] If the two are not the same, the first prestress of the prestressed steel strands in the bonded prestressed containment is compensated to obtain the corrected second prestress of the prestressed steel strands in the unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment.

[0090] Here, the first stress variable of the prestressed steel bundle in the bonded prestressed containment refers to the stress variable of the finite element unit of the prestressed steel bundle in the bonded prestressed containment. That is, when the first ultimate bearing capacity is applied to the bonded prestressed containment, the stress variable of the finite element unit of the prestressed steel bundle in the bonded prestressed containment at that moment is extracted. It can be understood that the preset load size in this embodiment is the same as the size of the first ultimate bearing capacity. In this way, by applying a preset load to the bonded prestressed containment, the calculation conditions required for the unbonded prestressed containment during calculation and analysis can be simulated.

[0091] The unbonded prestressed containment can be a PE (Polyethylene) unbonded prestressed containment. Among them, the prestressed steel bundle contains multiple steel strands, each of which is wrapped with a layer of PE sheath on the outside and filled with anti-corrosion lubricating grease inside. Its friction coefficient is relatively low, which can provide higher effective prestress. It can be used in the prestressed system of the nuclear power plant containment to reduce the amount of prestressed materials and save construction time. It should be noted that unbonded prestressed steel bundles can also be designed in other ways, and this application does not limit this.

[0092] The second stress variable of the prestressed steel tendons in the unbonded prestressed containment refers to the stress variable of the finite element unit of the prestressed steel tendons in the unbonded prestressed containment.

[0093] If the two are different, it means that the finite element model of the bonded prestressed containment cannot be directly used to characterize the finite element model of the unbonded prestressed containment, and the first prestress of the prestressed steel strands in the bonded prestressed containment needs to be compensated.

[0094] During implementation, the first prestress can be compensated according to the fact that the stress variables of each finite element unit of the prestressed steel bundle in the unbonded prestressed containment are the same, so as to obtain the second prestress. That is, the stress variables of each finite element unit of the prestressed steel bundle in the bonded prestressed containment are adjusted so that the stress variables of each finite element unit of the prestressed steel bundle in the bonded prestressed containment are equal and equal to the stress variables of each finite element unit of the prestressed steel bundle in the unbonded prestressed containment.

[0095] It should be noted that the first prestress is compensated by compensating stress so that the stress variables of each finite element unit of the prestressed steel bundle in the unbonded prestressed containment are the same. The corresponding compensating stress in the finite element model of the bonded prestressed containment can be a positive compensating stress (such as a "positive value" is a positive compensating stress) or a negative compensating stress (such as a "negative value" is a negative compensating stress).

[0096] It can be understood that by obtaining the second prestress of the prestressed steel strands in the modified unbonded prestressed containment, the ultimate bearing capacity of the unbonded prestressed containment is calculated in the finite element model of the bonded prestressed containment, and a more accurate ultimate bearing capacity of the unbonded prestressed containment is calculated.

[0097] The method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell of the present invention obtains the first ultimate bearing capacity of the bonded prestressed containment shell, determines whether the first stress variable of the prestressed steel bundle in the bonded prestressed containment shell is the same as the second stress variable of the prestressed steel bundle in the unbonded prestressed containment shell, and corrects the second prestress of the prestressed steel bundle in the unbonded prestressed containment shell. Because the second prestress of the prestressed steel bundle in the unbonded prestressed containment shell compensates for the uncoordinated deformation of the unbonded prestressed steel bundle and concrete, the prestress of the prestressed steel bundle in the unbonded prestressed containment shell can be accurately simulated, effectively improving the accuracy of the calculation of the ultimate bearing capacity of the unbonded prestressed containment shell, and improving the evaluation effect of the unbonded prestressed containment shell.

[0098] In some embodiments, step S2 further includes:

[0099] If the two are the same, the first ultimate bearing capacity of the bonded prestressed containment shell is directly determined as the ultimate bearing capacity of the unbonded prestressed containment shell.

[0100] Here, the two are the same, which means that the finite element model of the bonded prestressed containment can be directly used to characterize the finite element model of the unbonded prestressed containment to carry out the calculation of the ultimate bearing capacity of the unbonded prestressed containment.

[0101] During implementation, if the first stress variable of the prestressed steel strands in the bonded prestressed containment is the same as the second stress variable of the prestressed steel strands in the unbonded prestressed containment, the finite element model of the bonded prestressed containment is directly used to calculate the ultimate bearing capacity of the unbonded prestressed containment.

[0102] In this embodiment, by determining the first ultimate bearing capacity as the ultimate bearing capacity of the unbonded prestressed containment when the first stress variable of the prestressed steel bundle in the bonded prestressed containment is the same as the second stress variable of the prestressed steel bundle in the unbonded prestressed containment, the calculation process of the ultimate bearing capacity of the unbonded prestressed containment is simplified and the calculation efficiency of the ultimate bearing capacity of the unbonded prestressed containment is improved.

[0103] In some embodiments, the containment vessel comprises a steel lining, steel reinforcement,

[0104] In step S1, the first ultimate bearing capacity of the bonded prestressed containment is obtained by determining the first ultimate bearing capacity of the bonded prestressed containment according to the failure criterion, which specifically includes steps S11 to S12:

[0105] Step S11. gradually applying a preset load to the bonded prestressed containment shell;

[0106] Step S12: When the maximum plastic strain of the steel lining reaches a first preset threshold, the preset load applied by the bonded prestressed containment shell at this time is determined as the first ultimate bearing capacity.

[0107] Here, the failure criterion is a standard used to judge whether the structure of the containment reaches its limit state under a specific load, so as to evaluate the safety and reliability of the containment structure.

[0108] like Figure 4 For the steel lining of the containment, such as Figure 4 As shown, the first preset threshold is the maximum plastic strain limit of the steel liner, which characterizes the boundary of the loss of the sealing function of the steel liner. The first preset threshold can be determined empirically or obtained experimentally. The range of the first preset threshold can be 0.15%-0.45%. For example, the first preset threshold is 0.3%, that is, when the maximum plastic strain of the steel liner exceeds the interval of 0.3%, it is considered that the sealing function of the containment is lost.

[0109] In some other embodiments, when the maximum plastic strain of the steel bar reaches the second preset threshold, the preset load applied by the bonded prestressed containment shell at this time is determined as the first ultimate bearing capacity. Figure 5 For the steel bars of the containment, such as Figure 5 As shown, the second preset threshold is the strain limit of the steel bar, which can be the overall average tensile strain of the annular prestressed steel bar and / or the overall free field strain of other materials (such as steel lining and ordinary steel bar). The second preset threshold can be determined empirically or obtained experimentally. For example, the second preset threshold is the overall average tensile strain of the annular prestressed steel bar, which ranges from 0.6% to 1%, for example, 0.8%. The second preset threshold is the overall free field strain of other materials (such as steel lining and ordinary steel bar), which ranges from 0.2% to 0.6%, for example, 0.4%.

[0110] In this embodiment, by gradually applying the preset load and determining the first ultimate bearing capacity, a basis is provided for calculating the ultimate bearing capacity of the unbonded prestressed containment shell at the moment corresponding to the subsequent first ultimate bearing capacity.

[0111] In some embodiments, the determining whether the first stress variable of the prestressed steel bundle in the bonded prestressed containment shell is the same as the second stress variable of the prestressed steel bundle in the unbonded prestressed containment shell when a preset load corresponding to the first ultimate bearing capacity is applied to the bonded prestressed containment shell specifically includes steps S21 to S23:

[0112] Step S21. Determine whether the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is equal;

[0113] Step S22. If they are equal, determining that the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is the same as the second stress variable of each finite element unit of the prestressed steel strand in the unbonded prestressed containment;

[0114] Step S23. If they are not equal, determine that the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is different from the second stress variable of each finite element unit of the prestressed steel strand in the unbonded prestressed containment.

[0115] Here, the first stress variable of each finite element unit in any one of the steel strands of the prestressed steel bundle in the bonded prestressed containment can be obtained, and according to the first stress variable of each finite element unit of the steel strand, it is determined whether the first stress variable of each finite element unit of the prestressed steel bundle in the bonded prestressed containment is equal. For example, it is determined whether the first stress variables of all the finite element units of any one of the steel strands in the prestressed steel bundle are equal. If they are equal, it is determined that the first stress variables of each finite element unit of the prestressed steel bundle in the bonded prestressed containment are equal; if they are not equal, it is determined that the first stress variables of each finite element unit of the prestressed steel bundle in the bonded prestressed containment are not equal. In this way, the efficiency of determining whether the first stress variables of each finite element unit of the prestressed steel bundle in the bonded prestressed containment are equal can be improved.

[0116] In some other embodiments, the first stress variable of each finite element unit in each steel strand in the prestressed steel bundle may also be judged to determine whether the first stress variable of each finite element of the prestressed steel bundle in the bonded prestressed containment is equal.

[0117] It can be understood that if the first stress variables of each finite element unit of the prestressed steel bundle in the bonded prestressed containment are equal, it means that the established finite element model of the bonded prestressed containment is close to the finite element model of the unbonded prestressed containment, that is, in the finite element model of the bonded prestressed containment, the deformation of the prestressed steel bundle in concrete and the deformation of the prestressed steel bundle in concrete in the unbonded prestressed containment can be used to calculate the ultimate bearing capacity of the unbonded prestressed containment.

[0118] In this embodiment, by judging whether the first stress variable of each finite element unit of the prestressed steel bundle in the bonded prestressed containment is equal, it can be determined whether the first stress variable of each finite element unit of the prestressed steel bundle in the bonded prestressed containment is the same as the second stress variable of each finite element unit of the prestressed steel bundle in the unbonded prestressed containment, thereby improving the calculation efficiency of the ultimate bearing capacity of the unbonded prestressed containment.

[0119] In some embodiments, the first prestress of the prestressed steel strand in the bonded prestressed containment is compensated to obtain the second prestress of the prestressed steel strand in the unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment, specifically including steps S24 to S25:

[0120] Step S24. The deformation of each steel strand in the unbonded prestressed steel strand is set to be uniform, so as to compensate for the first prestress of the bonded prestressed steel strand and obtain the second prestress of the unbonded prestressed steel strand.

[0121] Here, the deformation of each steel strand in the unbonded prestressed steel strand is set to be uniform, that is, under the action of a preset load of the first ultimate bearing capacity, the prestressed steel strand in the unbonded prestressed containment can slide freely in the concrete along the length direction to redistribute stress, and the stress variables of the same steel strand at different positions (different finite element units) are the same.

[0122] In some embodiments, step S24 specifically includes:

[0123] Step S241. Obtaining a first total deformation of the prestressed steel strands in the bonded prestressed containment;

[0124] Step S242. Determine a second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment vessel according to the first total deformation;

[0125] Step S243. Determine the compensation stress of each finite element unit according to the second average stress variable of each steel strand and the stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment;

[0126] Step S244. Determine the second prestress of the prestressed steel strands in the unbonded prestressed containment shell based on the compensation stress of each finite element unit and the first prestress of the bonded prestressed steel strands.

[0127] In this embodiment, by obtaining the first total deformation of the prestressed steel strand and determining the second average stress variable, a more accurate second prestress of the prestressed steel strand in the unbonded prestressed containment can be determined, thereby determining a more accurate ultimate bearing capacity of the unbonded prestressed containment.

[0128] Step S25. Calculate the ultimate bearing capacity of the unbonded prestressed containment shell according to the second prestress of the unbonded prestressed steel strands.

[0129] In this embodiment, by obtaining the second prestress of the unbonded prestressed steel strands, because the second prestress compensates for the uncoordinated deformation of the unbonded prestressed steel strands and concrete, the prestress of the prestressed steel strands in the unbonded prestressed containment can be accurately simulated, thereby effectively improving the accuracy of the calculation of the ultimate bearing capacity of the unbonded prestressed containment and improving the evaluation effect of the unbonded prestressed containment.

[0130] In some embodiments, step S241 specifically includes:

[0131] According to the following formula (1), the first total deformation ΔL of the prestressed steel tendons in the bonded prestressed containment is calculated:

[0132]

[0133] Wherein, ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa); s is the distance between the finite element unit and the starting point of the steel strand (m); Δσ 有粘结 is the stress variable of the finite element unit of the prestressed steel strand in the bonded prestressed containment under the preset load (MPa);

[0134] Step S242 specifically includes:

[0135] According to the following formula (2), the second average stress variable Δσ of each steel strand in the prestressed steel strand in the unbonded prestressed containment is calculated: PE :

[0136] Δσ PE =ΔL / L×E s (2)

[0137] Among them, Δσ PE is the second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment (MPa), ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa);

[0138] Step S243 specifically includes:

[0139] The compensation stress of each finite element is calculated according to the following formula (3):

[0140] σ 补偿 =Δσ PE -Δσ 有粘结 (3)

[0141] Among them, σ 补偿 is the compensation stress (MPa) of each finite element.

[0142] Here, the calculated compensation stress σ for each finite element is 补偿 It has a direction, which can be positive or negative. It can be understood that a "positive value" is a positive compensating stress, and a "negative value" is a negative compensating stress.

[0143] In this embodiment, the first total deformation, the second average stress variable, and the compensating stress of each finite element unit are calculated respectively through the calculation formulas of the first total deformation, the second average stress variable, and the compensating stress of each finite element unit, which can compensate for the uncoordinated deformation of the unbonded prestressed steel strands and concrete, and provide a basis for accurately simulating the prestress of the prestressed steel strands in the unbonded prestressed containment.

[0144] In some embodiments, before step S1, the method further includes:

[0145] A finite element model of a bonded prestressed containment shell is established; the finite element model includes concrete, steel lining, steel bars and prestressed steel strands.

[0146] Here, a finite element model of the bonded prestressed containment can be established in the finite element software according to the construction drawings. Figures 3 to 6 As shown, the finite element model includes the concrete, steel lining, reinforcement and prestressed steel tendons of the containment.

[0147] Embodiment 2:

[0148] The specific implementation process of the method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell in this embodiment is explained below in conjunction with specific application examples.

[0149] At present, the prestressing system of prestressed reinforced concrete containment designed in China is a post-tensioned bonded prestressing system, and only the monitoring steel bundle uses an unbonded oil-filled or wax-filled steel bundle. With the development of nuclear power, in order to balance safety and economy, single-layer containment has gradually become the development trend of nuclear power plant containment. Prestressed concrete containment has added the function of resisting external disasters and commercial large aircraft collisions. In order to achieve the above functions, the prestressing system of the containment is required to be repairable after damage. In view of the increase in the design life of nuclear power plants and the need for later life extension, the prestressing system needs to be re-tensioned or replaced. After the duct of the bonded prestressing system is grouted, the prestressed steel bundle and the containment become a deformed and coordinated whole, which cannot be repaired after damage. The unbonded prestressing system has become the preferred target. The friction coefficient of PE (Polyethylene) unbonded prestressing is relatively low, which can provide higher effective prestressing. It can reduce the amount of prestressing materials and save construction time when applied to the prestressing system of the nuclear power plant containment.

[0150] Domestic calculations of the ultimate bearing capacity of in-service containment structures are mostly based on bonded prestressing. For unbonded prestressed systems, after the prestressing construction is completed, the prestressed steel strands are constrained in the direction perpendicular to the length of the steel strands, but can slide along the length direction. Due to the complexity of the containment structure, the variety of prestressed steel strands, and the constant adjustment of the direction when bypassing the penetration, which results in the length direction of most prestressed steel strands not always coinciding with a certain coordinate direction of the overall Cartesian coordinate system. At present, the mainstream finite element analysis software at home and abroad is mostly based on the overall Cartesian coordinate system for modeling and calculation, which makes it impossible to directly simulate the complex spatial distribution of unbonded prestressed steel strands. In response to the above problems, the present invention proposes a method for determining the ultimate bearing capacity of the unbonded prestressed containment of a nuclear power plant PE.

[0151] The present invention proposes a method for determining the ultimate bearing capacity of the PE unbonded prestressed containment of a nuclear power plant, which can more accurately evaluate the ultimate bearing capacity of the containment. Figure 2 As shown, the technical solution of the present invention includes steps 1 to 5:

[0152] Step 1: Establish a finite element model of the containment with bonded prestress and conduct analysis to obtain the ultimate bearing capacity.

[0153] (1) Establish a finite element model of the containment, such as Figures 3 to 6 As shown,

[0154] 1) According to the construction drawings, a finite element model of the containment is established in the finite element software, including four parts: concrete, steel lining, steel bars and prestressed steel strands. Large openings need to be considered in the model.

[0155] 2) Nonlinear material parameters are used for various materials in the model.

[0156] (2) Calculate the ultimate bearing capacity based on bonded prestress

[0157] 1) According to the actual situation of the ultimate bearing capacity analysis of the containment, determine the working conditions required for calculation.

[0158] 2) When performing model calculation and analysis, the above-mentioned calculation conditions must be fully and reasonably considered.

[0159] 3) According to the determined failure criterion, the ultimate bearing capacity moment of the containment is determined and the stress of the prestressed steel strands at that moment is extracted.

[0160] Step 2. Determine whether the result is reasonable based on the steel tendon stress increment. If it is unreasonable, process the steel tendon stress at the ultimate bearing capacity moment to obtain the compensating stress load;

[0161] Step 3. Superimpose the initial prestress before pressurization and the compensating stress load as the corrected initial prestress.

[0162] 1) Considering that the friction coefficient of PE unbonded prestressed steel strand is very small, it is believed that after the containment is loaded, the steel strand can slide freely along the length direction to redistribute stress, and the stress variables at different positions of the same steel strand are the same.

[0163] 2) Based on the calculation results of the ultimate bearing capacity of the bonded prestressed containment, the post-processing method is used to calculate the deformation of all units of each steel strand according to the stress variable. The total deformation is obtained by summing the unit deformation for each steel strand, as shown in formula (1).

[0164] 2) Calculate the average stress variable of each steel strand after stress redistribution based on the total deformation, length and elastic modulus of each steel strand, see formula (2).

[0165] 3) Subtract the initial calculated stress variable of each unit of each steel strand from the average stress variable after stress redistribution of each steel strand to obtain the compensation stress of each unit of the steel strand, as shown in the following formula.

[0166]

[0167] Δσ PE =ΔL / L×E s (2)

[0168] σ 补偿 =Δσ PE -Δσ 有粘结 (3)

[0169] in:

[0170] Δσ PE—Actual stress change of PE unbonded prestressed steel strand at the ultimate bearing capacity (MPa);

[0171] ΔL—total deformation of a single steel strand after analysis of bonded prestressed steel strand (m);

[0172] L—total length of a single strand before loading (m);

[0173] E s —Elastic modulus of steel strand (MPa);

[0174] s—the distance between the unit and the starting point of the steel bundle (m);

[0175] Δσ 有粘结 —Calculated stress variable (MPa) of each element of the tendon after analysis of bonded prestressed steel strands;

[0176] σ 补偿 —Compensation stress load required for the steel strand to transform from bonded to PE unbonded (MPa).

[0177] Step 4. Re-conduct the ultimate bearing capacity analysis according to the revised initial prestress;

[0178] Specifically, the initial prestress before pressurization is superimposed on the calculated compensation stress as the revised initial prestress, and the ultimate bearing capacity calculation is carried out again according to the revised initial prestress.

[0179] Step 5. Iterate steps (2) to (4) as needed to obtain suitable results.

[0180] In this embodiment, by obtaining the ultimate bearing capacity, calculating the compensating stress load, and determining the corrected initial prestress, a more accurate ultimate bearing capacity of the unbonded prestressed concrete containment can be obtained compared with the calculation results of the ultimate bearing capacity of the existing bonded prestressed concrete containment.

[0181] Embodiment 3:

[0182] The present invention also provides a safety assessment method for a nuclear power plant, comprising:

[0183] Determine the ultimate bearing capacity of the unbonded prestressed containment shell according to the calculation method of the ultimate bearing capacity of the unbonded prestressed containment shell described in Example 1 or Example 2;

[0184] According to the ultimate bearing capacity of the unbonded prestressed containment, the safety of the nuclear power plant is evaluated to ensure the safe operation of the nuclear power plant.

[0185] In this embodiment, by determining the ultimate bearing capacity of the unbonded prestressed containment and conducting a safety assessment of the nuclear power plant, a more accurate ultimate bearing capacity of the unbonded prestressed containment is determined, thereby improving the assessment effect of the unbonded prestressed containment.

[0186] Embodiment 4:

[0187] like Figure 7 As shown, the present invention also provides a device for calculating the ultimate bearing capacity of an unbonded prestressed containment shell, the device 100 comprising:

[0188] An acquisition module 11, which is configured to acquire a first ultimate bearing capacity of a bonded prestressed containment shell;

[0189] The processing module 12 is connected to the acquisition module 11 and is configured to determine whether a first stress variable of the prestressed steel bundle in the bonded prestressed containment is the same as a second stress variable of the prestressed steel bundle in the unbonded prestressed containment when a preset load corresponding to the first ultimate bearing capacity is applied to the bonded prestressed containment:

[0190] If the two are not the same, the first prestress of the prestressed steel strands in the bonded prestressed containment is compensated to obtain the corrected second prestress of the prestressed steel strands in the unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment.

[0191] In some embodiments, the processing module 12 is also used to directly determine the first ultimate bearing capacity of the bonded prestressed containment as the ultimate bearing capacity of the unbonded prestressed containment when the first stress variable of the prestressed steel bundle in the bonded prestressed containment is the same as the second stress variable of the prestressed steel bundle in the unbonded prestressed containment.

[0192] In some embodiments, the containment vessel comprises a steel lining, steel reinforcement,

[0193] The first ultimate bearing capacity of the bonded prestressed containment is obtained by determining the first ultimate bearing capacity of the bonded prestressed containment according to the failure criterion. The obtaining module 11 includes:

[0194] A loading unit for gradually applying a preset load to the bonded prestressed containment;

[0195] The determination unit is connected to the loading unit and is used to determine the preset load applied by the bonded prestressed containment shell as the first ultimate bearing capacity when the maximum plastic strain of the steel lining reaches a first preset threshold.

[0196] In some embodiments, the processing module 12 includes:

[0197] A judgment unit, used to judge whether the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is equal;

[0198] a first processing unit connected to the judging unit, for determining that a first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is the same as a second stress variable of each finite element unit of the prestressed steel strand in the unbonded prestressed containment if a judgment result of the judging unit is equal;

[0199] The second processing unit is connected to the judgment unit and is used to determine that the first stress variable of each finite element unit of the prestressed steel bundle in the bonded prestressed containment is different from the second stress variable of each finite element unit of the prestressed steel bundle in the unbonded prestressed containment if the judgment result of the judgment unit is unequal.

[0200] In some embodiments, the processing module 12 further includes:

[0201] an obtaining unit, connected to the first processing unit, for setting the deformation of each steel strand in the unbonded prestressed steel strand to be uniform, so as to compensate the first prestress of the bonded prestressed steel strand and obtain the second prestress of the unbonded prestressed steel strand;

[0202] The calculation unit is connected with the obtaining unit and is used for calculating the ultimate bearing capacity of the unbonded prestressed containment shell according to the second prestress of the unbonded prestressed steel tendons.

[0203] In some embodiments, obtaining the unit comprises:

[0204] A first acquisition subunit is used to obtain a first total deformation of the prestressed steel strands in the bonded prestressed containment shell;

[0205] A first determining subunit, connected to the first acquiring subunit, is used to determine a second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment shell according to the first total deformation;

[0206] A second determining subunit, connected to the first determining subunit, is used to determine the compensation stress of each finite element unit according to the second average stress variable of each steel strand and the stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment;

[0207] The third determining subunit is connected to the second determining subunit and is used to determine the second prestress of the prestressed steel strands in the unbonded prestressed containment shell according to the compensation stress of each finite element unit and the first prestress of the bonded prestressed steel strands.

[0208] In some embodiments, the first acquisition subunit is further used to calculate the first total deformation ΔL of the prestressed steel strands in the bonded prestressed containment shell according to the following formula (1):

[0209]

[0210] Wherein, ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa); s is the distance between the finite element unit and the starting point of the steel strand (m); Δσ 有粘结 is the stress variable of the finite element unit of the prestressed steel strand in the bonded prestressed containment under the preset load (MPa);

[0211] The first determination subunit is also used to calculate the second average stress variable Δσ of each steel strand in the prestressed steel strand in the unbonded prestressed containment according to the following formula (2): PE :

[0212] Δσ PE =ΔL / L×E s (2)

[0213] Among them, Δσ PE is the second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment (MPa), ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa);

[0214] The second determination subunit is also used to calculate the compensation stress of each finite element unit according to the following formula (3):

[0215] σ 补偿 =Δσ PE -Δσ 有粘结 (3)

[0216] Among them, σ 补偿 is the compensation stress (MPa) of each finite element.

[0217] In some embodiments, the apparatus further comprises:

[0218] The establishment module is connected to the acquisition module and is configured to establish a finite element model of a bonded prestressed containment shell; the finite element model includes concrete, steel lining, steel bars and prestressed steel strands.

[0219] It should be noted that this embodiment is a corresponding device of the method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell in the above-mentioned embodiment 1. The method in embodiment 1 can be implemented by adopting this device. The specific implementation method can refer to the description in the method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell, and this embodiment will not be repeated here.

[0220] It should be clear that the present application is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present application is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present application.

[0221] The functional blocks shown in the above block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present application are programs or code segments that are used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segment can be downloaded via a computer network such as the Internet, an intranet, etc.

[0222] The above are only specific implementation methods of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

Claims

1. A method for calculating the ultimate bearing capacity of an unbonded prestressed containment, characterized in that: include: S1. Obtaining the first ultimate bearing capacity of the bonded prestressed containment; S2. Determine whether the first stress variable of the prestressed steel strand in the bonded prestressed containment is the same as the second stress variable of the prestressed steel strand in the unbonded prestressed containment when a preset load corresponding to the first ultimate bearing capacity is applied to the bonded prestressed containment: If the two are not the same, the first prestress of the prestressed steel strands in the bonded prestressed containment is compensated to obtain the corrected second prestress of the prestressed steel strands in the unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment.

2. The method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell according to claim 1, characterized in that: Step S2 also includes: If the two are the same, the first ultimate bearing capacity of the bonded prestressed containment shell is directly determined as the ultimate bearing capacity of the unbonded prestressed containment shell.

3. The method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell according to claim 1, characterized in that: The containment shell includes a steel lining and steel bars. In step S1, obtaining the first ultimate bearing capacity of the bonded prestressed containment is to determine the first ultimate bearing capacity of the bonded prestressed containment according to the failure criterion, which specifically includes: S11. Gradually apply a preset load to the bonded prestressed containment; S12. When the maximum plastic strain of the steel lining reaches a first preset threshold value, the preset load applied to the bonded prestressed containment shell at this time is determined as the first ultimate bearing capacity.

4. The method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell according to claim 1, characterized in that: The step of judging whether a first stress variable of a prestressed steel strand in the bonded prestressed containment shell is the same as a second stress variable of a prestressed steel strand in the unbonded prestressed containment shell when a preset load corresponding to a first ultimate bearing capacity is applied to the bonded prestressed containment shell specifically includes: S21. Determine whether the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is equal; S22. If they are equal, then determine that the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is the same as the second stress variable of each finite element unit of the prestressed steel strand in the unbonded prestressed containment; S23. If they are not equal, it is determined that the first stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment is different from the second stress variable of each finite element unit of the prestressed steel strand in the unbonded prestressed containment.

5. The method for calculating the ultimate bearing capacity of unbonded prestressed containment according to claim 1, characterized in that: The first prestress of the prestressed steel strands in the bonded prestressed containment is compensated to obtain the second prestress of the prestressed steel strands in the modified unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment, specifically including: S24. The deformation of each steel strand in the unbonded prestressed steel strand is set to be uniform, so as to compensate for the first prestress of the bonded prestressed steel strand and obtain the second prestress of the unbonded prestressed steel strand; S25. Calculate the ultimate bearing capacity of the unbonded prestressed containment shell based on the second prestress of the unbonded prestressed steel tendons.

6. The method for calculating the ultimate bearing capacity of unbonded prestressed containment according to claim 5, characterized in that: Step S24 specifically includes: S241. Obtaining a first total deformation of the prestressed steel strands in the bonded prestressed containment; S242. Determine a second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment according to the first total deformation; S243. Determine the compensation stress of each finite element unit according to the second average stress variable of each steel strand and the stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment; S244. Determine the second prestress of the prestressed steel strands in the unbonded prestressed containment shell based on the compensating stress of each finite element unit and the first prestress of the bonded prestressed steel strands.

7. The method for calculating the ultimate bearing capacity of the unbonded prestressed containment shell according to claim 6, characterized in that: Step S241 specifically includes: According to the following formula (1), the first total deformation ΔL of the prestressed steel tendons in the bonded prestressed containment is calculated: Wherein, ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa); s is the distance between the finite element unit and the starting point of the steel strand (m); Δσ 有粘结 is the finite element stress variable of the prestressed steel strand in the bonded prestressed containment under the preset load (MPa); Step S242 specifically includes: According to the following formula (2), the second average stress variable Δσ of each steel strand in the prestressed steel strand in the unbonded prestressed containment is calculated: PE : Board PE =ΔL / L×E s (2) Among them, Δσ PE is the second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment (MPa), ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa); Step S243 specifically includes: The compensation stress of each finite element is calculated according to the following formula (3): s 补偿 =Ds PE -Board 有粘结 (3) Among them, σ 补偿 is the compensation stress (MPa) of each finite element.

8. The method for calculating the ultimate bearing capacity of unbonded prestressed containment according to any one of claims 1 to 7, characterized in that: Before step S1, the method further includes: A finite element model of a bonded prestressed containment shell is established; the finite element model includes concrete, steel lining, steel bars and prestressed steel strands.

9. A safety assessment method for a nuclear power plant, characterized in that: include: The ultimate bearing capacity of the unbonded prestressed containment shell is determined according to the calculation method of the ultimate bearing capacity of the unbonded prestressed containment shell according to any one of claims 1 to 8; According to the ultimate bearing capacity of the unbonded prestressed containment, the safety of the nuclear power plant is evaluated to ensure the safe operation of the nuclear power plant.

10. A device for calculating the ultimate bearing capacity of an unbonded prestressed containment, characterized in that: The device comprises: An acquisition module, configured to acquire a first ultimate bearing capacity of a bonded prestressed containment shell; The processing module is connected to the acquisition module and is configured to determine whether a first stress variable of a prestressed steel bundle in the bonded prestressed containment is the same as a second stress variable of a prestressed steel bundle in the unbonded prestressed containment when a preset load corresponding to a first ultimate bearing capacity is applied to the bonded prestressed containment: If the two are not the same, the first prestress of the prestressed steel strands in the bonded prestressed containment is compensated to obtain the corrected second prestress of the prestressed steel strands in the unbonded prestressed containment to calculate the ultimate bearing capacity of the unbonded prestressed containment.

11. The device for calculating the ultimate bearing capacity of unbonded prestressed containment according to claim 10, characterized in that: The processing module also includes: an obtaining unit, connected to the first processing unit, for setting the deformation of each steel strand in the unbonded prestressed steel strand to be uniform, so as to compensate the first prestress of the bonded prestressed steel strand and obtain the second prestress of the unbonded prestressed steel strand; The calculation unit is connected with the obtaining unit and is used for calculating the ultimate bearing capacity of the unbonded prestressed containment shell according to the second prestress of the unbonded prestressed steel tendons.

12. The device for calculating the ultimate bearing capacity of unbonded prestressed containment according to claim 11, characterized in that: The obtaining unit comprises: A first acquisition subunit is used to obtain a first total deformation of the prestressed steel strands in the bonded prestressed containment shell; A first determining subunit, connected to the first acquiring subunit, is used to determine a second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment shell according to the first total deformation; A second determining subunit, connected to the first determining subunit, is used to determine the compensation stress of each finite element unit according to the second average stress variable of each steel strand and the stress variable of each finite element unit of the prestressed steel strand in the bonded prestressed containment; The third determining subunit is connected to the second determining subunit and is used to determine the second prestress of the prestressed steel strands in the unbonded prestressed containment shell according to the compensation stress of each finite element unit and the first prestress of the bonded prestressed steel strands.

13. The device for calculating the ultimate bearing capacity of unbonded prestressed containment according to claim 12, characterized in that: The first acquisition subunit is further used to calculate the first total deformation ΔL of the prestressed steel strands in the bonded prestressed containment shell according to the following formula (1): Wherein, ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa); s is the distance between the finite element unit and the starting point of the steel strand (m); Δσ 有粘结 is the finite element stress variable of the prestressed steel strand in the bonded prestressed containment under the preset load (MPa); The first determination subunit is also used to calculate the second average stress variable Δσ of each steel strand in the prestressed steel strand in the unbonded prestressed containment according to the following formula (2): PE : Board PE =ΔL / L×E s (2) Among them, Δσ PE is the second average stress variable of each steel strand in the prestressed steel bundle in the unbonded prestressed containment (MPa), ΔL is the first total deformation (m); L is the total length of a single steel strand before applying the preset load (m); E s is the elastic modulus of the steel strand (MPa); The second determination subunit is also used to calculate the compensation stress of each finite element unit according to the following formula (3): s 补偿 =Ds PE -Board 有粘结 (3) Among them, σ 补偿 is the compensation stress (MPa) of each finite element.

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