A method for checking the structural strength of an upper module of a cylindrical FPSO based on SACS

Abstract

The application discloses a kind of based on SACS's cylinder type FPSO upper module structural strength checking method, it is related to marine petroleum engineering technical field. Including cylinder type FPSO upper module, wave break wall and ship body main deck, wherein, cylinder type FPSO upper module includes cylinder type FPSO module two-deck, cylinder type FPSO module process deck and cylinder type FPSO module leg column, including the following steps, step one: according to SACS software model element numbering rule and model simulation method, in combination with the number of cylinder type FPSO upper module, cylinder type FPSO upper module naming.The application can directly count into each module between upper portion and with wave break wall the mutual influence due to process deck is integral deck, make the calculation simulation of upper module more in line with actual situation, and the calculation result is more accurate.Avoid the difficulty that other modules cannot be considered to the coupling influence of the module when calculating the in-place strength of the sub-module.

Description

Technical Field

[0001] The invention relates to the technical field of offshore oil engineering, in particular to a SACS-based method for checking the structural strength of a cylindrical FPSO upper module. Background Art

[0002] FPSO is the abbreviation of floating production storage and offloading platform. It is a comprehensive offshore oil production base that integrates multiple functions such as personnel accommodation, production, oil storage, and external transportation. It is usually a ship-shaped. Most of them are single-point mooring and have the function of a weather vane. Under the action of wind and waves, the hull will rotate around the single point and always keep facing the waves. Its ship-shaped FPSO upper module (1) is a space frame structure mainly composed of pipes, beams, and plate components, such as Figure 1 As shown, the ship-type FPSO module second deck (11) and the ship-type FPSO module process deck (12) between each ship-type FPSO upper module (1) are not connected to each other and are independent of each other. The ship-type FPSO upper module (1) is designed and constructed in a modular manner and is integrated and installed on the main deck (4) of the hull through a gantry crane or a floating crane. Some of the ship-type FPSO module legs (13) between the ship-type FPSO upper module (1) and the hull are designed to be sliding connections to reduce the impact of the total longitudinal deformation of the hull on the module structure. Because each module is independent of each other, the module deck has no lateral support, and the lateral load is mainly borne by the ship-type FPSO module legs (13), so the ship-type FPSO module legs (13) are installed with a ship-type FPSO module diagonal brace (14) structure.

[0003] The cylindrical FPSO is a new type of floating production storage and offloading device with a cylindrical hull and a multi-point mooring method. It has obvious economic advantages in deep-water development, especially in the development of isolated oil fields and small remote oil fields. Unlike the upper modules of the ship-type FPSO, the upper modules of the cylindrical FPSO are connected to the cylindrical FPSO module second deck (21) and the cylindrical FPSO module process deck (22) as an integral deck. The process deck is connected to the main deck (4) of the hull through the under-deck columns and the hull wave walls (3) around the deck to form an integral platform structure. See attached. Figure 2 .

[0004] Because the topside modules are independent of each other, the in-situ working condition verification of the FPSO topside module structure is generally based on the symmetry of the port and starboard sides of the hull. The two modules, symmetrically distributed on either side of the hull's main axis, are generally modeled together. The hull motion and deformation data are then applied as loads for simulation calculations. However, for cylindrical FPSOs, since the process deck is an integral deck, the forces between the modules affect each other. If the block modeling and calculation method for the FPSO topside module is used, the coupling effects of the modules at the process deck connection cannot be accurately simulated.

[0005] In view of the structural characteristics of the cylindrical FPSO upper module, the present invention proposes an in-situ structural strength analysis method that models the module blocks, then integrates them into an overall model for analysis and verification, and optionally further splits the model for detailed calculation according to needs. Summary of the Invention

[0006] The object of the present invention is to provide a method for checking the structural strength of a cylindrical FPSO upper module based on SACS, so as to solve the problems raised in the above background technology.

[0007] To achieve the above-mentioned object, the present invention provides the following technical solution: a SACS-based method for verifying the structural strength of a cylindrical FPSO upper module, comprising a cylindrical FPSO upper module, a wave barrier, and a main deck of the hull, wherein the cylindrical FPSO upper module comprises a cylindrical FPSO module second deck, a cylindrical FPSO module process deck, and cylindrical FPSO module legs, comprising the following steps:

[0008] Step 1: Based on the SACS software model element numbering rules and model simulation methods, combined with the number of cylindrical FPSO upper modules, the naming of cylindrical FPSO upper modules, the number of layers of cylindrical FPSO module second deck and cylindrical FPSO module process deck, and the names and load conditions of cylindrical FPSO module second deck and cylindrical FPSO module process deck, follow the unified rules to formulate module modeling;

[0009] Step 2: According to the unified rules established in step 1, three-dimensional structural models of each upper module and hull wave wall of the cylindrical FPSO are established respectively, and various professional weights are loaded to generate SACS model files corresponding to each upper module and each block model of the hull wave wall of the cylindrical FPSO;

[0010] Step 3: Import the block model files of each upper module created in Step 2 into the same module model, complete the connection of bulk connecting structural members between each module and between each cylindrical FPSO upper module and the wave wall, combine the weight of each discipline such as mechanical, piping, and electrical in each module into the overall weight of the discipline on the cylindrical FPSO platform, form an overall model, and generate a SACS model file for the overall model;

[0011] Step 4: Using the integrated overall model from step 3, calculate the gravity load, wind load, and inertia load caused by the overall motion of the platform. Superimpose these loads to obtain the overall force of the overall model and generate a SACS combined solution file.

[0012] Step 5: Solve the overall model structural stress under the most unfavorable load obtained in step 4 and check the structural strength of the upper module. At the same time, generate detailed results of member stress and node deformation.

[0013] Step 6: Analyze the module. Apply the module boundary member force or node displacement extracted in step 5 at the module boundary, and superimpose it with the module's gravity, wind load, and motion load to obtain the overall force of the module. Perform detailed stress calculation and verification of the module.

[0014] Furthermore, in the step 1, the unified rules for block modeling are formulated under the SACS software model element numbering rules, using continuous digital numbering in segments and multi-digit character numbering to assign meanings to segments, so as to distinguish model elements by module, deck layer, profession, or working condition. The model element distinguishing numbers include node numbers, plate numbers, wind area numbers, basic weights / loads, and combined weights / loads, and model elements that need to remain consistent across all modules are uniformly numbered.

[0015] Furthermore, in step 2, the establishment of block models of each cylindrical FPSO upper module and hull wave wall can be carried out simultaneously by multiple people, each person is responsible for one or more modules, and reasonable arrangements are made according to the project plan and professional manpower conditions. Each block model generates its own SACS model file, and all block models use the same coordinate direction and coordinate origin definition.

[0016] Furthermore, in step 3, the module models are integrated into the overall analysis model, including two parts: finite element model integration and professional weight combination. The finite element model integration is based on one of the three-dimensional structural models of the cylindrical FPSO upper module and the wave-breaking wall of the hull, and the other upper module models are imported to complete the connection between the cylindrical FPSO upper modules and between the cylindrical FPSO upper modules and the wave-breaking wall.

[0017] The combination of the weight of each profession, according to the module combination of its professional weight, forms the total weight of each module, according to the profession combination of its module weight, forms the total weight of each profession, and finally combines to obtain the overall weight of all upper modules.

[0018] Furthermore, in step 4, the wind load of each module does not take into account the wind speed reduction caused by the shading of the upstream module in the wind direction;

[0019] To calculate the inertial force load caused by motion, a six-degree-of-freedom combination of translational acceleration and rotational acceleration at the corresponding reference point is used to take into account the influence of the acceleration difference of the module at different platform positions. The superposition of wind load, weight load and inertial force load must be in the same direction to obtain the most unfavorable force condition of the module.

[0020] Furthermore, while calculating the structural stress, a detailed result report of the internal forces and node deformations of the cylindrical FPSO upper module boundary and the junction between the cylindrical FPSO upper module and the cylindrical FPSO upper module is calculated and output.

[0021] Furthermore, step six is ​​an optional step. Block modeling and integrated overall model analysis and verification can complete all in-situ calculation and analysis. According to project requirements, the overall model can be further split into multiple single module models to perform more detailed calculation and evaluation for each module.

[0022] Step six is ​​to extract the rod force or node deformation at the module boundary through step five as the boundary constraint of the sub-module model to perform detailed calculation and analysis of the single module model.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This SACS-based method for verifying the structural strength of cylindrical FPSO topside modules directly accounts for the interactions between modules and between the topside modules and the wave wall due to the integral nature of the process deck. This makes topside module simulations more realistic and accurate. It also avoids the problem of failing to account for the coupling effects of other modules on the module's process deck boundary when calculating in-situ strength for each module. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the upper module structure of the ship-type FPSO of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the upper module of the cylindrical FPSO of the present invention;

[0027] Figure 3 Schematic diagram of a typical block SACS model of a cylindrical FPSO upper module of the present invention;

[0028] Figure 4 This is a schematic diagram of the cylindrical FPSO wave-breaking wall model of the present invention;

[0029] Figure 5 This is a schematic diagram of the overall model of the present invention integrating all upper modules and the wave-breaking wall model;

[0030] Figure 6 This is a schematic diagram of the present invention further splitting the single module model;

[0031] Figure 7 It is a schematic diagram of the process of the present invention;

[0032] Figure 8 This is a schematic diagram of the plate numbering in step 1 of the present invention;

[0033] Figure 9 This is a schematic diagram of basic weight / load naming in step 1 of the present invention;

[0034] Figure 10 This is a schematic diagram of naming the combined weight / load in step 1 of the present invention;

[0035] Figure 11 Schematic diagram of the cross-sectional numbering of the round tube and the cross-sectional numbering of the welded I-beam in step 1 of the present invention;

[0036] Figure 12 This is a schematic diagram of the numbering of the cross-section groups in step 1 of the present invention.

[0037] In the figure: 1. Ship-type FPSO upper module; 11. Ship-type FPSO module second deck; 12. Ship-type FPSO module process deck; 13. Ship-type FPSO module leg column; 14. Ship-type FPSO module diagonal brace; 2. Cylindrical FPSO upper module; 21. Cylindrical FPSO module second deck; 22. Cylindrical FPSO module process deck; 23. Cylindrical FPSO module leg column; 3. Wave wall; 4. Ship's main deck. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] It should be noted that, in the description of the present invention, the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0040] Furthermore, it should be understood that for the sake of ease of description, the sizes of the various components shown in the drawings are not drawn according to actual proportions. For example, the thickness or width of certain layers may be exaggerated relative to other layers.

[0041] It should be noted that like numbers and letters represent similar items in the following figures, so once an item is defined or described in one figure, it will not need to be further discussed and described in detail in the description of the subsequent figures.

[0042] like Figure 3-Figure 6As shown, the present invention provides a technical solution: a SACS-based method for checking the structural strength of a cylindrical FPSO upper module, comprising a cylindrical FPSO upper module 2, a wave-breaking wall 3, and a hull main deck 4. The cylindrical FPSO upper module 2 comprises a cylindrical FPSO module second deck 21, a cylindrical FPSO module process deck 22, and a cylindrical FPSO module leg column 23. The method comprises the following steps:

[0043] Step 1: According to the SACS software model element numbering rules and model simulation method, combined with the number of cylindrical FPSO upper modules 2, the naming of cylindrical FPSO upper modules 2, the number of layers of cylindrical FPSO module second deck 21 and cylindrical FPSO module process deck 22, and the names and load conditions of cylindrical FPSO module second deck 21 and cylindrical FPSO module process deck 22, modular modeling is formulated in accordance with unified rules. The formulated unified rules for modular modeling are to use continuous digital numbers in segments and assign meanings to multi-digit character numbers in segments under the SACS software model element numbering rules, so as to distinguish model elements that need to be distinguished by module, deck layer, professional distinction, or working condition. The model element distinguishing number includes node number, plate number, wind area number, basic weight / load and combined weight / load, and the model elements that need to be consistent across all modules are uniformly numbered.

[0044] The specific method is:

[0045] (1) Model elements (node ​​numbers, plate numbers, wind area numbers, basic weights / loads, and combined weights / loads) that need to be distinguished by module, deck level, discipline, or operating condition shall be numbered by using consecutive numbers in sections and assigning meaning to multi-digit numbers in sections.

[0046] ① For node numbering, the four-digit number "0001" can be used. This number can be assigned to different upper modules and hull wave wall models in segments, allowing each model to have a dedicated node number segment. For example, the thousand node numbers 0001 to 1000 can be assigned to module one, and the number segment 1001 to 2999 can be assigned to module two. The size of the segment range should be determined based on the estimated scale of each module.

[0047] ② Plate numbers can be composed of a first letter followed by three consecutive digits, "P001." The first letter represents a module, and the three consecutive digits identify the different deck levels by block, such as P for Module 1 and Q for Module 2. The three digits following the letter are assigned to different deck levels by section, such as 001-200 for the second deck, and 201-500 for the process deck. Thus, deck plates numbered P001-P200 represent the second deck of Module 1, those numbered P001-P200 represent the second deck of Module 1, and those numbered Q201-Q500 represent the process deck of Module 2. The size of the section range should be determined based on the estimated size of each module. Large modules can be assigned two letters as the first letter of the number, such as plate numbers beginning with Q and R both represent Module 2.

[0048] ③ Basic weights / loads can be named using a four-character string. The first two characters indicate the module to which the weight belongs, the third character indicates the discipline to which the weight belongs, and the fourth character indicates the working condition to which the weight belongs. For example, the dry weight of mechanical equipment on a PR-I module can be named P1MD, where P1 represents the PR-I module, M represents the mechanical discipline, and D represents the dry weight of the equipment.

[0049] ④. Combined weights / loads can be named using a four-character string. The first three characters indicate the module to which the weight belongs, and the fourth character indicates the operating condition to which the weight belongs. For example, the non-structural dry weight loads of the PR-I module can be combined and named PR1D, where D stands for dry weight and PR1 stands for process module one. The combined operating loads of all modules are defined as DWTO, and the combined extreme loads of all modules are defined as DWTE, where the letter O represents the operating condition, the letter E represents the extreme condition, and DWT represents all upper modules.

[0050] (2) Unify the numbering of model elements (member sections, member groups) that need to remain consistent across all modules, for example:

[0051] ①. All members of the same size are assigned the same cross-section (SECT) across all model files. Circular tube cross-section numbers are uniformly assigned using a six- or seven-digit string consisting of the outer diameter, "X," and the wall thickness. For example, a Φ914X38 tube (914 diameter, 38 wall thickness) is assigned the cross-section number 914X38. Welded I-beam cross-sections are uniformly assigned using a seven-digit string consisting of "H," the beam height, and the beam width. For example, the cross-section number H120400 represents all I-beams with a height of 1200 and a flange width of 400. For rolled I-beams, sections from the SACS model library can be selected directly, eliminating the need for additional definition.

[0052] ②. Across all model files, members with the same cross-section are collectively defined as a cross-section group. For round tubes, the cross-section group is uniformly designated as "T" followed by two digits, and for I-beams, "H" or "P" followed by two digits. The two-digit number is a sequential number determined by the number of round tubes and I-beams used in the model, or a two-digit combination that represents a specific diameter-wall-thickness combination or beam height-width combination. For example, all 914x38 tubes are grouped as T93, and all H120 / 400 I-beams are grouped as H12.

[0053] ③ All decks of the same thickness are defined as a unified PLATE GROUP, such as 8mm decks are uniformly defined as PL8.

[0054] (3) Unify the modeling scope, simulation method, and main technical requirements of each upper module, for example:

[0055] ① All primary and secondary structures, including columns, braces, deck beams, decks, and other structural components that contribute to the overall stiffness of the module are modeled. Tertiary structures or auxiliary structures can be applied to the structural model through load types;

[0056] ② Joints should be uniformly constructed at the theoretical deck elevation shown in the drawings. Joint eccentricities and offsets of structural members should be appropriately simulated in the model to examine local bending moments and shear effects. For example, the braces of the tubular joints should be offset to the chord surface according to their actual dimensions.

[0057] Mechanical, electrical and other professional weights are uniformly simulated using WEIGHT SKID, and live loads (LIVE LOAD) are uniformly loaded using AREA LOAD.

[0058] Step 2: Follow the unified rules established in step 1, such as Figure 3 and Figure 4 As shown, three-dimensional structural models of each upper module 2 and hull wave-breaking wall 3 of the cylindrical FPSO are respectively established, and various professional weights are loaded to generate SACS model files corresponding to each block model of each upper module 2 and hull wave-breaking wall 3 of the cylindrical FPSO. Specifically, the establishment of the block models of each cylindrical FPSO upper module 2 and hull wave-breaking wall 3 can be carried out by multiple people at the same time, and each person is responsible for one or more modules. The reasonable arrangement is made according to the project plan and professional manpower situation. Each block model generates its own SACS model file, and all block models use the same coordinate direction and coordinate origin definition.

[0059] The specific method is:

[0060] (1) Depending on the project plan and professional manpower situation, modeling work can be carried out by multiple people at the same time, with each person responsible for one or more modules;

[0061] (2) All block models use the same coordinate direction and coordinate origin. The positive direction of the X axis is the bow direction, the positive direction of the Y axis points to the port side, and the positive direction of the Z axis is vertically upward. The origin of the X and Y axes is located at the center of the circular hull, and the origin of the Z axis is located on the keel surface of the hull.

[0062] (3) Figure 3 The figure shows the schematic diagram of the PR-I module model. A three-dimensional bar analysis and calculation model of the wave-breaking wall structure is established separately as the boundary condition model, as shown in Figure 4 Each block model generates its own SACS model file (SACINP file).

[0063] Step 3: If Figure 5 As shown, the block model files of each upper module established in step 2 are imported into the same module model, and the connection of the bulk connecting structural members between each module and between each cylindrical FPSO upper module and the wave-breaking wall is completed. The weight of each discipline such as machinery, piping, and electrical in each module is combined into the overall weight of the discipline on the cylindrical FPSO platform to form an overall model, and a SACS model file of the overall model is generated. The overall analysis model of each module model is integrated, including two parts: finite element model integration and combination of each discipline weight. Among them, the integration of the finite element model is based on one of the three-dimensional structural models of each cylindrical FPSO upper module 2 and the wave-breaking wall 3 of the hull, and the other upper module models are imported to complete the connection between each cylindrical FPSO upper module 2 and between the cylindrical FPSO upper module 2 and the wave-breaking wall 3; the combination of each discipline weight is to combine the weight of each discipline according to the module to form the total weight of each module, and to combine the weight of each discipline according to the discipline to form the total weight of each discipline, and finally to obtain the overall weight of all upper modules;

[0064] The specific method is:

[0065] (1) Finite element model integration

[0066] ① Use the IMPORT function of the PRECEDE function module of the SACS software to import the SACS model files of other upper modules based on the hull wave wall model;

[0067] ② Through the user interface of the PRECEDE function module of the SACS software, the modeling of bulk connection components that were not simulated in the block models between the upper modules and between the upper modules and the wave-breaking wall was manually completed. The program automatically merged the nodes or rods that were modeled in all modules at the same position.

[0068] (2) Weight combinations for each profession

[0069] ① Through the user interface of the PRECEDE function module of SACS software or the text content copy and edit operation of the model file, the professional weight of each module is combined according to the module to form the total weight of each module;

[0070] ② Through the user interface of the PRECEDE function module of SACS software or the text content copying and editing of the model file, the weight of each major in each module is combined according to the major to form the total weight of each major;

[0071] ③. Based on the professional combination or module combination, the total weight of the upper modules of the entire platform is obtained.

[0072] Step 4: Using the integrated overall model from step 3, calculate the gravity load, wind load, and inertia load caused by the overall movement of the platform. Superimpose the various loads to obtain the overall force of the overall model and generate a SACS combined solution file (COMBINED SOLUTION FILE). The wind load of each module does not consider the wind speed reduction caused by the shading of the upstream module in the wind direction; calculate the inertia load caused by movement, using a six-degree-of-freedom combination of translational acceleration and rotational acceleration at the corresponding reference point to take into account the influence of the acceleration difference of the module at different positions on the platform. The superposition of wind load, weight load, and inertia load must be in the same direction to obtain the most unfavorable force condition of the module.

[0073] The specific method is:

[0074] (1) Gravity load solution: DEAD is used to solve the deadweight of the structure. The vertical acceleration ACCL function is combined with the INCWGT command in step S3 to solve the gravity load of each module, the overall weight load of each module, and the overall weight load of all modules.

[0075] (2) Combine the loads of the same discipline in each module into the overall load of the discipline on the platform. At the same time, the gravity output of the single discipline of the single module is still retained;

[0076] (3) Wind load calculation considers eight wind directions, with wind direction intervals of 45 degrees. For a certain wind direction, the wind area on the windward side of each module is fully included in the wind load calculation, that is, the wind load of each module does not take into account the wind speed reduction caused by the shading of the upstream module in the wind direction;

[0077] (4) The inertial force load caused by motion is calculated using a combination of the translational acceleration and rotational acceleration at the corresponding reference point to account for the influence of the module's acceleration differences at different platform positions. The translational acceleration at the module's center of gravity does not need to be converted. Considering the phase difference between the accelerations of different degrees of freedom, there are 64 possible combinations of positive and negative six-degree-of-freedom accelerations for a specific wave direction.

[0078] (5) Using the load superposition function (COMBINE SOLUTION FILE) of the SACS software, the solution file generated by the wind load calculation is used as the main file, the weight load solution file is used as the second input file, and the inertia force load solution file is used as the third input file to generate the upper module overall load combination solution file.

[0079] (6) When superimposing, the gravity load, wind load and inertia load of the module equipment and facilities should be combined according to the most unfavorable conditions to ensure that the most unfavorable stress conditions of the module are covered.

[0080] Step 5: Solve the structural stress of the overall model under the most unfavorable load obtained in step 4 and check the structural strength of the upper module, and generate detailed results of the member stress and node deformation. Specifically, the load superposition function of the SACS software in step 4 is used to calculate the structural stress while calculating and outputting a detailed result report of the internal force and node deformation of the member at the boundary of the cylindrical FPSO upper module 2 and the junction between the cylindrical FPSO upper module 2 and the cylindrical FPSO upper module 2.

[0081] (1) Use CODE CHECK of the POST PROCESSING module of SACS software to check the strength of the rod;

[0082] (2) Use TUBULAR CONNECTION CHECK in the POST PROCESSING module of SACS software to check the punching shear strength of tubular joints;

[0083] (3) For the above verification, the input file COMMON SOLUTION FILE must use the COMBINED SOLUTION FILE generated in step S4;

[0084] (4) Select to output detailed result reports of the upper module boundary and the internal forces (MEMBER FORCE) and node deformations (JOINT DEFLECTION) at the module-to-module interface.

[0085] 6. Step 6: Analyze the module, such as Figure 6As shown, the module boundary member force or node displacement extracted from step five is applied at the module boundary, and superimposed with the module's gravity, wind load and motion load to obtain the overall force of the module, and the detailed stress calculation and verification of the module are performed. Specifically, this step is an optional step. Block modeling and integrated overall model analysis and verification can complete all in-situ calculation and analysis. According to project requirements, the overall model can be split into multiple single module models again to perform more detailed calculation and evaluation for each module. In addition, step six is ​​to extract the member force or node deformation at the module boundary in step five as the boundary constraint of the sub-module model to perform detailed calculation and analysis of the single module model.

[0086] (1) Analytical model;

[0087] (2) Extract the gravity and wind area of ​​other modules in the single module model working condition combination;

[0088] (3) Applying the extracted boundary node deformation;

[0089] (4) Combine the loads;

[0090] (5) Perform module verification.

[0091] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for checking the structural strength of a cylindrical FPSO upper module based on SACS, comprising a cylindrical FPSO upper module (2), a wave-breaking wall (3) and a hull main deck (4), wherein: The cylindrical FPSO upper module (2) comprises a cylindrical FPSO module second deck (21), a cylindrical FPSO module process deck (22) and a cylindrical FPSO module leg column (23), and is characterized in that it comprises the following steps: Step 1: According to the SACS software model element numbering rules and model simulation method, combined with the number of cylindrical FPSO upper modules (2), the naming of cylindrical FPSO upper modules (2), the number of layers of cylindrical FPSO module second deck (21) and cylindrical FPSO module process deck (22), and the names and load conditions of cylindrical FPSO module second deck (21) and cylindrical FPSO module process deck (22), follow the unified rules to formulate module modeling; Step 2: According to the unified rules established in step 1, three-dimensional structural models of each upper module (2) and hull wave-breaking wall (3) of the cylindrical FPSO are established respectively, and each professional weight is loaded to generate SACS model files corresponding to each block model of each upper module (2) and hull wave-breaking wall (3) of the cylindrical FPSO; Step 3: Import the block model files of each upper module established in step 2 into the same module model, complete the connection of the bulk connecting structural rods between each module and between each cylindrical FPSO upper module (2) and the wave-breaking wall (3), combine the weight of each discipline of machinery, piping, and electricity in each module into the overall weight of the discipline on the cylindrical FPSO platform, form an overall model, and generate a SACS model file of the overall model; Step 4: Using the integrated overall model from step 3, calculate the gravity load, wind load, and inertia load caused by the overall motion of the platform. Superimpose these loads to obtain the overall force of the overall model and generate a SACS combined solution file. Step 5: Solve the overall model structural stress under the most unfavorable load obtained in step 4 and check the structural strength of the upper module. At the same time, generate detailed results of member stress and node deformation. Step 6: Analyze the module. Apply the module boundary member force or node displacement extracted in step 5 at the module boundary, and superimpose it with the module's gravity, wind load, and motion load to obtain the overall force of the module. Perform detailed stress calculation and verification of the module.

2. The method for checking the structural strength of a cylindrical FPSO topside module based on SACS according to claim 1, characterized in that: In the step 1, the unified rule for block modeling is formulated under the SACS software model element numbering rules, using continuous digital numbering in sections and multi-digit character numbering to assign meanings to segments, to distinguish model elements that need to be distinguished by module, deck layer, profession, or working condition. The model element distinguishing numbering includes node number, plate number, wind area number, basic weight / load, and combined weight / load, and model elements that need to remain consistent across all modules are uniformly numbered.

3. The method for verifying the structural strength of a cylindrical FPSO topside module based on SACS according to claim 1, characterized in that: In the second step, the block models of each cylindrical FPSO upper module (2) and the hull wave-breaking wall (3) can be established by multiple people at the same time, with each person responsible for one or more modules. The work is reasonably arranged according to the project plan and professional manpower conditions. Each block model generates its own SACS model file, and all block models use the same coordinate direction and coordinate origin definition.

4. The method for verifying the structural strength of a cylindrical FPSO topside module based on SACS according to claim 1, characterized in that: In the step 3, the module models are integrated into an overall analysis model, including two parts: finite element model integration and professional weight combination. The finite element model integration is based on one of the three-dimensional structural models of the cylindrical FPSO upper module (2) and the wave-breaking wall (3) of the hull, and the other upper module models are imported to complete the connection between the cylindrical FPSO upper modules (2) and between the cylindrical FPSO upper modules (2) and the wave-breaking wall (3); The combination of the weight of each profession, according to the module combination of its professional weight, forms the total weight of each module, according to the profession combination of its module weight, forms the total weight of each profession, and finally combines to obtain the overall weight of all upper modules.

5. The method for verifying the structural strength of a cylindrical FPSO topside module based on SACS according to claim 1, characterized in that: In step 4, the wind load of each module does not take into account the wind speed reduction caused by the shading of the upstream module in the wind direction; To calculate the inertial force load caused by motion, a six-degree-of-freedom combination of translational acceleration and rotational acceleration at the corresponding reference point is used to take into account the influence of the acceleration difference of the module at different platform positions. The superposition of wind load, weight load and inertial force load must be in the same direction to obtain the most unfavorable force condition of the module.

6. The method for verifying the structural strength of a cylindrical FPSO topside module based on SACS according to claim 1, characterized in that: In the step 5, the load superposition function of the SACS software used in the step 4 is used to calculate the structural stress, and at the same time, a detailed result report of the internal force and node deformation of the rods at the boundary of the cylindrical FPSO upper module (2) and the intersection position between the cylindrical FPSO upper module (2) and the cylindrical FPSO upper module (2) is calculated and output.

7. The method for verifying the structural strength of a cylindrical FPSO topside module based on SACS according to claim 1, characterized in that: Step 6 is an optional step. Block modeling and integrated overall model analysis and verification can complete all in-situ calculation and analysis. According to project requirements, the overall model can be split into multiple single module models to perform more detailed calculation and evaluation for each module. Step 6 is to extract the rod force or node deformation at the module boundary through step 5 as the boundary constraint of the sub-module model to perform detailed calculation and analysis of the single module model.

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