Superstructure hull structure simplified coupling beam method for large ships

Abstract

The application relates to a large ship superstructure hull structure simplified coupling beam method, which regards the whole hull as two beams with elastic supports, i.e. a superstructure beam and a main hull beam, and sets a transition layer between the main hull and the superstructure; by establishing control equations of the coupling beam structure, the bending moment and curvature relationship between the superstructure and the main hull, the shear coupling relationship and the relationship between the coupling stiffness and the limit shear displacement are obtained, so that the interaction between the large superstructure and the main hull is effectively characterized. The application can effectively characterize the interaction between the large superstructure and the main hull made of the same or different materials, and provides a beneficial reference for the limit strength research, design optimization and the like of the ship with the large superstructure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ship structure, in particular to a large ship superstructure hull structure simplified coupling beam method. BACKGROUND

[0002] For large passenger ships, luxury cruise ships and other ships, the superstructure participates in the overall longitudinal bending to a large extent, and the interaction between the main hull and the superstructure is very complex, which is one of the long-term concerns of the shipbuilding industry. Obviously, it is too conservative not to take into account the superstructure in the overall strength design, especially for ships with large superstructures, the superstructure participates in the overall longitudinal bending to a large extent, and its influence cannot be ignored. It is of great significance to explore the interaction between large superstructure and main hull and the coupling relationship in each direction to improve the mechanical properties, structural safety and other aspects of large passenger ships and luxury cruise ships.

[0003] In the existing research methods, the finite element method can effectively simulate the mechanical response of the hull structure, but the calculation precision, time and other aspects are limited by the model simplification degree, structure size and computer hardware configuration. The theoretical method has good timeliness, but the analytical expressions of horizontal shear force and vertical tension and compression force in the double beam theory are cosine trigonometric functions, which have certain differences with the actual stress distribution, and the end point effect of the superstructure is not considered. The coupling beam theory is difficult to solve and requires the length and material of the superstructure and the main hull to be equal. SUMMARY

[0004] In order to solve the above problems, the present application provides a large ship superstructure hull structure simplified coupling beam method.

[0005] The specific scheme is as follows:

[0006] A large ship superstructure hull structure simplified coupling beam method, the entire hull is regarded as two beams with elastic support, i.e. the superstructure beam and the main hull beam, and the region between the main hull and the superstructure is set as a transition layer.

[0007] The bending moment equations of the superstructure beam and the main hull beam are set as:

[0008]

[0009] Wherein, E H , E S represent the elastic modulus of the main hull and the superstructure respectively; I H , I S represent the moment of inertia of the main hull and the superstructure respectively; v H , v S represent the deflection of the main hull and the superstructure respectively; double prime represents the second derivative; p H , p Srespectively represent the vertical forces on the main hull and superstructure; p represents the vertical coupling force, and p = k(v H -v S ), k represents the vertical stiffness coefficient of the superstructure deck; e H , e S respectively represent the vertical distances between the neutral axis of the main hull and superstructure and the interface of the transition deck; q(x) represents the horizontal shear stress intensity at the interface of the main hull and superstructure, and x represents the coordinate value in the axial direction of the hull;

[0010] The control equations of the main hull and superstructure are set as follows:

[0011] E H I H v” = M H + M Q

[0012] E S I S v” = M S + M Q

[0013] M H represents the bending moment caused by the combined action of the self-gravity G H , the water pressure F W , and the vertical coupling force F V between the main hull and superstructure; M Q represents the bending moment caused by the longitudinal coupling force N H,S between the main hull and superstructure; M S represents the bending moment caused by the self-gravity G H and the vertical coupling force F V ; M Q represents the bending moment caused by the longitudinal coupling force N H,S ;

[0014] The longitudinal shear force between the i-th span structure of the main hull and superstructure and the transition deck is set to be the same, and the curvature of the deflection curve of the beam in the i-th span of the main hull and superstructure is set to be the same, so the bending moment and curvature relationship between the superstructure and the main hull is:

[0015]

[0016] wherein M H,i = k i M V,i and M S,i = (1-k i )M V,i , M V,i represents the vertical bending moment of the i-th span hull beam caused by the load; M H,i represents the vertical bending moment of the i-th span of the main hull; MS,i k represents the vertical bending moment of the superstructure within the i-th span; i This indicates the weight of the main hull in bearing the vertical bending moment; φ H,i φ S,i Let e ​​represent the curvature of the main hull and the i-th span of the superstructure at their respective neutral axes; H,i e S,i N represents the vertical distance from the neutral axis of the main hull and the i-th span of the superstructure to the interface of the transfer layer; i I represents the longitudinal shear force across the i-th transition layer; H,i I S,i Let represent the moments of inertia of the main hull and the superstructure within the i-th span, respectively;

[0017] The formula for calculating the longitudinal displacement difference is set as follows:

[0018]

[0019] Where, △δ i Δδ represents the longitudinal displacement difference at the interface between the end faces of the i-th and (i+1)-th spans of the main hull and superstructure at the transfer layer; j This represents the longitudinal displacement difference at the transfer layer interface between the end faces of the j-th and (j+1)-th spans of the main hull and superstructure; i and j both represent the span numbers; n indicates that there are n spans in the half-ship; L represents the longitudinal length of a span; i represents the span number; e i This represents the vertical distance between the neutral axis of the i-th span of the main hull and the superstructure; e j A represents the vertical distance between the neutral axis of the j-th span of the main hull and the superstructure; H,j A S,j δ represents the cross-sectional area of ​​the j-th span of the main hull and the superstructure, respectively; H,i δ S,i T represents the longitudinal displacement of the end faces of the main hull and superstructure at the interface of the transfer layer between the i-th and i+1-th spans, respectively; j This represents the longitudinal shear stiffness across the j-th transition layer.

[0020] Furthermore, the formula for calculating the longitudinal shear stiffness of the i-th span of the transfer layer is:

[0021]

[0022] Wherein, S1, S2, and S3 represent the total number of longitudinal bulkheads, transverse bulkheads, and pillars within a span of the transfer layer, respectively; s1, s2, and s3 represent the serial numbers of the longitudinal bulkheads, transverse bulkheads, and pillars within a span of the transfer layer, respectively; T Ps1 T represents the longitudinal shear stiffness of the s1th longitudinal bulkhead within the span of the transfer layer; qs2T s2 represents the longitudinal shear stiffness of the transverse bulkhead of the s2th transverse in the conversion layer; bs3 T s3 represents the longitudinal shear stiffness of the s3th column in the conversion layer.

[0023] Further, the longitudinal shear stiffness T of the longitudinal bulkhead is calculated by the following formula: P

[0024]

[0025] Wherein, t represents the thickness of the longitudinal bulkhead; H represents the height of the longitudinal bulkhead; G represents the shear modulus; L represents the length of the longitudinal bulkhead. P n

[0026] Further, the calculation formula of the longitudinal shear stiffness of the column and the transverse bulkhead is the same, that is:

[0027]

[0028] Wherein, T represents the longitudinal shear stiffness of the column or the transverse bulkhead; A represents the cross-sectional area of the column or the transverse bulkhead; I represents the cross-sectional moment of inertia of the column or the transverse bulkhead; H represents the height of the column or the transverse bulkhead; v represents the Poisson's ratio. b b b b

[0029] Further, the limit shear displacement of each span is set as the minimum value of the limit shear displacement of all longitudinal bulkheads, transverse bulkheads and columns in the span.

[0030] Further, the superstructure beam and the main hull beam are independent beams with the same length of the simplified main hull and superstructure and symmetrical along the midship section.

[0031] The application adopts the above technical scheme, on the basis of the double-beam theory and the coupled-beam theory, by researching the coupling relationship in all directions among the superstructure, the conversion layer and the main hull, a simplified coupled-beam method suitable for the ship hull structure with large superstructure is proposed, which can effectively represent the interaction of the large superstructure and the main hull made of the same or different materials, and provides a beneficial reference for the limit strength research and design optimization of the ship with large superstructure. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Fig. 1 shows a typical transverse section of the ship hull beam with large superstructure in the embodiment of the application.

[0033] Figure 2 Fig. 2 shows the deformation of each span of the ship hull beam in the embodiment of the application in the hog state.

[0034] Figure 3 ​​​​​​​The ship beam 1 / 4 finite element model in this embodiment is shown.

[0035] Figure 4 The coupling beam method and finite element results comparison chart in this embodiment are shown.

[0036] Figure 5 The longitudinal displacement difference and coupling stiffness relationship diagram in this embodiment is shown.

[0037] Figure 6 The bending moment distribution coefficient diagram in this embodiment is shown.

[0038] Figure 7 The coupling shear and stiffness relationship diagram in this embodiment is shown. DETAILED DESCRIPTION

[0039] To further illustrate the embodiments, the present application provides accompanying drawings. These drawings are part of the disclosure of the present application, which mainly serve to illustrate the embodiments, and can be explained in conjunction with the related description of the specification to understand the operating principle of the embodiments. With reference to these contents, those skilled in the art should understand other possible implementations and advantages of the present application.

[0040] The present application will be further illustrated in conjunction with the accompanying drawings and specific embodiments.

[0041] Embodiment one:

[0042] The embodiment of the present application provides a simplified coupling beam method for superstructure hull structure of large ships. The following will be introduced from four aspects of control equation, bending moment and curvature relationship, longitudinal shear coupling relationship and arbitrary span shear stiffness and ultimate shear displacement relationship.

[0043] (1) Control equation

[0044] When studying the superstructure strength problem, the separation body method can be adopted, that is, the entire ship body is separated into three parts of the main ship body, the superstructure deck and the superstructure side wall, and the elastic mechanics plane problem method is used for solving, but the method is complicated in calculation and not strong in practicability. The coupling beam method regards the entire ship body as two beams with elastic support each other, that is, the superstructure beam and the main ship body beam. The bending moment equations of the two beams can be listed as follows:

[0045]

[0046] In the formula, E H , E S respectively represent the elastic modulus of the main ship body and the superstructure; I H , I S respectively represent the moment of inertia of the main ship body and the superstructure; v H , v Sv H , and v S represent the deflections of the main hull and superstructure, respectively; p H , and p S represent the vertical forces on the main hull and superstructure, respectively; p represents the vertical coupling force, and p = k(v H -v S ), k represents the superstructure deck vertical stiffness coefficient; e H , and e S represent the vertical distances from the neutral axis of the main hull and superstructure to the interface of the transition layer, respectively; q(x) represents the horizontal shear stress intensity at the interface of the main hull and superstructure, and x represents the coordinate value in the axial direction of the hull. For a long-hull ship type such as a luxury cruise ship, the rigidity coefficient k of the elastic foundation can be taken as k ≈ ∞, so the deflections of the superstructure and the main hull are equal, i.e., v H ≈ v W = v.

[0047] The bending moment causing the bending deformation of the main hull is divided into two parts, one is the bending moment M V caused by the combined action of the self-gravity G H , the water pressure F H,S , and the vertical coupling force F Q between the main hull and the superstructure; the other is the bending moment M H caused by the longitudinal coupling force N V between the main hull and the superstructure. The bending moment causing the bending deformation of the superstructure is also divided into two parts, one is the bending moment M S caused by the self-gravity G H,S and the vertical coupling force F Q ; the other is the bending moment M H caused by the longitudinal coupling force N H . Then the governing equations of the main hull and the superstructure, i.e., the bending moment balance equations, can be expressed as:

[0048] E H I Q v” = M S + M S (3)

[0049] E S I Q v” = M i + M i (4)

[0050] Considering the structural characteristics of a ship with a large superstructure, a repetitive multi-span structure based on a typical transverse section as shown in FIG. 1 is taken as an example. There is a clear recess area between the main hull and the superstructure, which is called the transition layer. The deformation of each span of the hull girder in the hogging state in the region from the ship's middle to the stern is shown in FIG. 2. Figure 1

[0051] (2) Relationship between bending moment and curvature

[0052] Longitudinal shear force of the i-th span of the transition deck i Balance, we get

[0053] N i = N H,i = N S,i (5)

[0054] In the formula, N H,i and N S,i respectively represent the longitudinal shear force between the main hull and the superstructure of the i-th span structure and the transition deck.

[0055] From the same deflection curve of the main hull and the superstructure in the i-th span beam, we have:

[0056] φ i = φ H,i = φ S,i = v" (6)

[0057] In the formula, φ i represents the curvature of the deflection curve of the i-th span beam, φ H,i and φ S,i respectively represent the curvatures of the main hull and the superstructure of the i-th span structure at their respective neutral axes.

[0058] The vertical bending moment of the i-th span hull beam caused by its own gravity and water pressure and other loads is M V,i Since the superstructure participates in the overall longitudinal bending, the vertical bending moment is borne by the main hull and the superstructure together, so the vertical bending moment of the i-th span of the main hull and the superstructure is M H,i and M S,i respectively represent:

[0059] M H,i = k i M V,i (7)

[0060] M S,i = (1-k i )M V,i (8)

[0061] In the formula, k i represents the weight of the main hull participating in bearing the vertical bending moment.

[0062] The deflection curve curvatures of the main hull and the superstructure in the i-th span beam can be respectively represented as

[0063]

[0064]

[0065] where e H,i , e S,i respectively represent the vertical distance between the neutral axis of the main hull and the ith bay structure of the superstructure to the interface of the transition deck.

[0066] According to the equilibrium condition of formula (5), formula (9) and (10) can be obtained as follows:

[0067]

[0068] It can be seen that k i , Φ i are functions of unknown shear force N i .

[0069] (3) Longitudinal shear coupling relationship

[0070] Taking the main hull and the ith bay structure of the superstructure, the longitudinal linear strain of the main hull and the superstructure at the interface with the transition deck is defined as ε H,i and ε S,i , which can be expressed as follows:

[0071]

[0072] where A H,i , A S,i respectively represent the cross-sectional area of the main hull and the ith bay structure of the superstructure.

[0073] Based on the above, the longitudinal displacement δ H,i and δ S,i of the end face of the main hull and the superstructure at the interface of the transition deck between the ith bay and the ith+1 bay structure can be calculated:

[0074]

[0075] where L represents the longitudinal length of a bay.

[0076] Let △δ i represent the difference between the longitudinal displacement of the end face of the main hull and the superstructure at the interface of the transition deck between the ith bay and the ith+1 bay structure, then:

[0077] △δ i = δ H,i - δ S,i (17)

[0078] By rearranging formula (13) to formula (17), we can obtain:

[0079]

[0080] where e idenotes the vertical distance between the main hull and the superstructure in the ith span, i.e. e i = e H,i + e S,i To further simplify the above equation, define a quantity D i related to the tensile and compressive stiffness of the main hull and superstructure, i.e.

[0081]

[0082] Assume that the half ship has n spans, and the longitudinal shear stiffness of the conversion layer in the ith span is T i , then N i can be expressed as

[0083]

[0084] Bring equation (19) and equation (20) into equation (18) to get

[0085]

[0086] Through the above equation, an n-order linear equation group about △δ i can be established, so as to obtain the longitudinal displacement difference of any span of the ship beam. When the parameters T, e, D, E H , E S , I H , I S of each span are constant values, the relationship between △δ i and the vertical bending moment can be expressed in the following form:

[0087]

[0088] In the formula, α and β are coefficients, which satisfy the following relationships respectively:

[0089]

[0090] And define the stiffness matrix [K] as:

[0091]

[0092] (4) Relationship between shear stiffness of any span and ultimate shear displacement

[0093] The support members of the conversion layer are mainly longitudinal and transverse bulkheads and columns, which mainly provide vertical and longitudinal coupling forces in the overall longitudinal bending of the ship beam. In section (3), it is assumed that the vertical stiffness of the support member is large enough, and this section only considers the shear stiffness and shear coupling force of the support member.

[0094] For a longitudinal bulkhead in a span, its longitudinal shear stiffness T P is expressed as follows:

[0095]

[0096] where t represents the longitudinal bulkhead thickness; H P represents the longitudinal bulkhead height; G represents the shear modulus; L n represents the longitudinal bulkhead length.

[0097] For a column in a span, its shear stiffness T b is:

[0098]

[0099] where A b represents the cross-sectional area of the column or the transverse bulkhead; I b represents the cross-sectional moment of inertia of the column or the transverse bulkhead; H b represents the height of the column or the transverse bulkhead; v represents the Poisson's ratio.

[0100] When the bulkhead is a transverse bulkhead, it can be treated as a column under longitudinal shear. Then the total shear stiffness of the transfer story in the ith span is:

[0101]

[0102] where S1, S2, S3 represent the total number of longitudinal bulkheads, transverse bulkheads, and columns in a span of the transfer story, respectively; s1, s2, s3 represent the serial number of the longitudinal bulkheads, transverse bulkheads, and columns in a span of the transfer story, respectively; T Ps1 represents the longitudinal shear stiffness of the s1th longitudinal bulkhead in a span of the transfer story; T qs2 represents the longitudinal shear stiffness of the s2th transverse bulkhead in a span of the transfer story; T bs3 represents the longitudinal shear stiffness of the s3th column in a span of the transfer story.

[0103] The ultimate shear displacements of the supporting members in a span are compared, and the minimum value is taken as the ultimate shear displacement δ u of the span, then:

[0104] δ u = min{δ p1 ,…,δ pm ,δ q1 ,…,δ qn ,δ b1 ,…,δ pz} (29)

[0105] where δ P1 represents the ultimate shear displacement of the first longitudinal bulkhead in a span of the transfer story; δ q1 represents the ultimate shear displacement of the first transverse bulkhead in a span of the transfer story; δ b1This represents the ultimate shear displacement of the first column within one span of the transfer layer; the other symbols follow the same pattern.

[0106] Simulation Experiment

[0107] To improve computational efficiency, this embodiment simplifies the main hull and superstructure into independent beams of equal length and symmetrical along the mid-section. Based on the finite element calculation platform and relevant data from existing literature, a... Figure 3 The diagram shows a quarter-scale model of the ship's hull beam. The input coordinate system for the calculation model is a Cartesian coordinate system, with the origin located at the intersection of the midship section and the baseline. The x-axis is along the ship's longitudinal direction, pointing positively from the origin towards the bow; the y-axis is along the ship's beam direction, pointing positively from the midship section towards the port side; and the z-axis is along the ship's vertical direction, pointing positively upwards from the hull baseline. Figure 3 As shown, the model constructed in this embodiment is divided into 15 spans along the ship's length, each span having equal length and consistent geometry. The main hull of the model is made of steel, and the superstructure is made of aluminum alloy. The total number of nodes is 739,572, and the total number of elements is 750,051. Among them, the beam elements are B31, with a quantity of 2,348; and the shell elements are S4R, with a quantity of 747,703.

[0108] Assuming the hull structure does not buckle under the mid-arch bending condition, the specific constraints are as follows: symmetric constraint at x=0; separate coupling points are designed on the end face of each span of the superstructure and main hull to apply bending moments; coupling elements are set between the superstructure and the main hull, with 21 elements per span.

[0109] Results Comparison

[0110] The longitudinal displacement difference of each span is calculated using the coupled beam method in this embodiment, and compared with the finite element calculation results. For example... Figure 4 As shown, the curve trends of the coupled beam method and the finite element results are quite consistent, and the data of each span have good agreement. The relative error of the longitudinal displacement difference of each span is less than 11%, which proves the accuracy and effectiveness of the coupled beam method.

[0111] Based on the coupled beam method, a passenger ship model with an aluminum alloy superstructure and a steel main hull was designed using typical cross-sections provided in existing literature to analyze the coupling effect between the superstructure and the main hull made of different materials. The ship is 180 meters long, 18.9 meters wide, 9.6 meters deep, and has a superstructure height of 12 meters. A quarter-scale model of the ship was used for the calculation, divided into 15 spans along the ship's length, each span being of equal length and having a consistent geometric configuration. It was assumed that the hull structure would not buckle under mid-arch bending.

[0112] The longitudinal displacement difference between the superstructure and the main hull was calculated using formula (21), and the result is as follows: Figure 5 As shown, the longitudinal displacement difference exhibits a relatively consistent trend with the coupling stiffness across different regions of the hull. To ensure...Figure 5 The content is clear, the horizontal coordinate is the logarithm of the coupling stiffness T. When the coupling stiffness is small, the displacement difference is almost constant; with lnT = 13 as the boundary (the dotted line in the figure), the longitudinal displacement difference decreases with the increase of the coupling stiffness, and the closer to the ship end, the more obvious the decreasing trend; when lnT increases to 20, the change of the longitudinal displacement difference with the coupling stiffness weakens and tends to be constant. This shows that the greater the stiffness of the superstructure coupled with the main ship in the fixed position, the smaller the longitudinal displacement difference; within the entire ship length, if the coupling stiffness is constant, the closer to the ship center, the smaller the longitudinal displacement difference, and vice versa.

[0113] The coupling beam method of the embodiment can effectively obtain the bending moment distribution coefficient of any span of the ship body, as shown in the following table: Figure 6 i The k Figure 6 in the table represents the proportional coefficient of the bending moment borne by the main ship under the hogging condition. For a certain fixed load condition, the total bending moment borne by the main ship and the superstructure in a certain span is a constant value, and the proportional coefficient corresponding to the main ship is large, so the bending moment borne by the superstructure is small. i

[0114] The coupling shear force N is calculated, and the results are shown in the following table: Figure 7 The trend of the coupling shear force curve with the change of the stiffness is relatively consistent for different regions of the ship body. When the coupling stiffness is small, the coupling shear force increases rapidly with the increase of the stiffness, and the closer to the ship center, the more intense the change trend; then the increasing trend of the coupling shear force slows down, and when the coupling stiffness T reaches 1.32x10 9 N / m, the coupling shear forces at different positions tend to be constant. As can be seen from the table, within the entire ship length, if the stiffness is the same, the closer to the ship center, the greater the coupling shear force, and vice versa. Figure 7

[0115] ​​​The embodiment of the application obtains a simplified coupling beam method by studying the coupling relationship among the superstructure, the transition layer and the main hull of a ship, and the method is suitable for luxury cruise ships, large passenger ships and other ships with large superstructures. The method clearly defines the control equation of the coupling beam structure and the role of the transition layer between the superstructure and the main hull, and can effectively obtain the bending moment-curvature relationship, the longitudinal shear coupling relationship and the relationship between the arbitrary span coupling stiffness and the ultimate shear displacement between the superstructure and the main hull, thereby effectively representing the interaction relationship between the large superstructure and the main hull. Through comparison and analysis of examples with the finite element method, the accuracy and effectiveness of the coupling beam method are verified. In addition, it is found by applying the coupling beam method that the degree of participation in the overall longitudinal bending of the end of the aluminum alloy superstructure is smaller than that of the middle part, and the closer to the end, the smaller the degree of participation, which makes up for the deficiency of the double beam theory that does not consider the end effect, and improves the limitation of the previous coupling beam theory that requires the main hull and the superstructure to be made of the same material. The coupling beam method provides a useful reference for the ultimate strength research and design optimization of ships with large superstructures.

[0116] Although the present application has been shown and described with respect to the preferred embodiments, it should be understood by the skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the application as defined in the appended claims.

Claims

1. A simplified coupled beam method for superstructure hull structures of large ships, characterized in that: The whole ship is regarded as two beams with elastic support, i.e. superstructure beam and main hull beam, and the region between the main hull and superstructure is set as the transition layer; The bending moment equations of the superstructure beam and main hull beam are set as: where E H , E S represent the elastic modulus of the main hull and superstructure, respectively; I H , I S represent the moment of inertia of the main hull and superstructure, respectively; v H , v S represent the deflection of the main hull and superstructure, respectively; the double prime represents the second derivative; p H , p S represent the vertical force on the main hull and superstructure, respectively; p represents the vertical coupling force, and p = k(v H -v S ), k represents the vertical stiffness coefficient of the superstructure deck; e H , e S represent the vertical distance between the neutral axis of the main hull and superstructure, respectively, and the interface of the conversion layer; q(x) represents the horizontal shear stress intensity at the interface of the main hull and superstructure, and x represents the coordinate value in the axial direction of the hull. The control equations of the main hull and superstructure are set as: E H I H v”=M H +M Q E S I S v”=M S +M Q M H denotes the bending moment caused by the self weight G H , the water pressure F W , and the vertical coupling force F V between the main hull and the superstructure; M Q denotes the bending moment caused by the longitudinal coupling force N H,S between the main hull and the superstructure; M S denotes the bending moment caused by the self weight G H and the vertical coupling force F V ; M Q denotes the bending moment caused by the longitudinal coupling force N H,S ; The longitudinal shear forces between the i-th span structure of the main hull and superstructure and the transition layer are set to be the same, and the curvatures of the deflection lines of the beams in the i-th span of the main hull and superstructure are set to be the same, so the bending moment and curvature relationship between the superstructure and main hull is: wherein M H,i = k i M V,i and M S,i = (1 - k i )M V,i , M V,i represents the vertical bending moment of the ith span girder caused by the load; M H,i represents the vertical bending moment of the main hull in the ith span; M S,i represents the vertical bending moment of the superstructure in the ith span; k i represents the weight of the main hull participating in bearing the vertical bending moment; e H,i , e S,i respectively represent the vertical distance between the neutral axis of the main hull, the superstructure in the ith span structure respectively and the interface with the transition layer; N i represents the longitudinal shear force of the transition layer in the ith span; I H,i , I S,i respectively represent the moment of inertia of the main hull, the superstructure in the ith span; The calculation formula of the longitudinal displacement difference is set as: wherein, Δδ i represents the longitudinal displacement difference of the end face between the ith and (i+1)th span structures of the main hull and superstructure at the transition deck interface; Δδ j represents the longitudinal displacement difference of the end face between the jth and (j+1)th span structures of the main hull and superstructure at the transition deck interface; i, j represent the serial number of the span; n represents the number of spans shared by the half ship; L represents the longitudinal length of a span; i represents the serial number of the span; e i represents the vertical distance between the center of gravity and the shaft in the ith span structure of the main hull and superstructure; e j represents the vertical distance between the center of gravity and the shaft in the jth span structure of the main hull and superstructure; A H,j , A S,j respectively represent the cross-sectional area of the main hull and the jth span structure of the superstructure; T j represents the longitudinal shear stiffness of the jth span transition deck.

2. Simplified coupled beam method for superstructure hull structures of large ships according to claim 1, characterized in that: The calculation formula of the longitudinal shear stiffness of the transition layer of the i-th span is: Wherein, S1, S2, S3 represent the total number of longitudinal bulkheads, transverse bulkheads and columns in the conversion layer one span respectively; s1, s2, s3 represent the serial number of longitudinal bulkheads, transverse bulkheads and columns in the conversion layer one span respectively; T Ps1 represents the longitudinal shear stiffness of the s1th longitudinal bulkhead in the conversion layer one span; T qs2 represents the longitudinal shear stiffness of the s2th transverse bulkhead in the conversion layer one span; T bs3 represents the longitudinal shear stiffness of the s3th column in the conversion layer one span.

3. Simplified coupled beam method for superstructure hull structures of large ships according to claim 2, characterized in that: The longitudinal shear stiffness T of the longitudinal bulkhead P The formula for calculating T is: where t represents the longitudinal bulkhead thickness; H P represents the longitudinal bulkhead height; G represents the shear modulus; L n represents the length of the longitudinal bulkhead.

4. Simplified coupled beam method for superstructure hull structures of large ships according to claim 2, characterized in that: The calculation formula of the longitudinal shear stiffness of the vertical bulkhead and transverse bulkhead is the same, i.e. where T b represents the longitudinal shear stiffness of the column or transverse bulkhead; A b represents the cross-sectional area of the column or transverse bulkhead; I b represents the cross-sectional moment of inertia of the column or transverse bulkhead; H b represents the height of the column or transverse bulkhead; v represents the Poisson's ratio.

5. The simplified coupled beam method for superstructure hull structures of large ships according to claim 1, characterized in that: The limit shear displacement of each span is set as the minimum value of the limit shear displacements of all longitudinal bulkheads, transverse bulkheads and vertical bulkheads in the span.

6. A simplified coupled beam method for superstructure hull structures of large ships according to claim 1, characterized in that: The superstructure beam and main hull beam are independent beams with equal length and symmetry along the midship section after simplification of the main hull and superstructure.

Images