Method for determining welding amount of half-ship floating pier falling ship body

Abstract

The invention discloses a method for determining the welding amount of a half-ship floating pier falling ship body, which comprises the following steps of: (1) determining a half-ship welding operation area in a dock according to a half-ship structure and a section division form, including a plate folding seam area, an aggregate welding area and an abrupt change position where a cabin tail section cannot be completely folded; (2) evaluating the total longitudinal strength of the half ship body according to the plate closure seam area determined in the step (1); (3) evaluating the local strength of the half ship body according to the abrupt change position, which is determined in the step (1) and cannot be completely closed, of the cabin tail section; (4) when the total longitudinal strength and the local strength in the steps (2) and (3) meet the design requirements, the longitudinal aggregate welding amount is determined through the step (5); and (5) the required plate thickness of the plane bulkhead plate of the ship is calculated, the actual plate thickness of the plane bulkhead plate of the ship is compared with the required plate thickness, and the longitudinal aggregate welding amount of the aggregate welding area is determined. According to the method, the minimum welding construction workload before the half ship in the dock enters the water can be determined, and the carrying construction efficiency in the half dock is improved.

Description

Technical Field

[0001] The invention relates to the technical field of shipbuilding, and in particular to a method for determining the welding amount of a half-ship floating landing hull. Background Art

[0002] In order to make rational use of the dock and improve construction efficiency, the whole ship and half ship are generally built in series in the same dock. In this way, when the whole ship is undocking, the half ship floats and moves to the position of the whole ship to land, and then the bow half ship is assembled, and the construction of the half ship starts at the back of the dock, and so on. However, when the whole ship and the half ship are constructed in parallel, the whole ship and the half ship are required to be launched after welding, which brings great difficulties to the allocation of manpower and material resources and planning management during the entire dock period. In the construction of ships in the dock, the whole ship's undocking node is often restricted by the half ship. In the traditional construction method, the half ship can only meet the launching conditions after all the segmented structures are installed and welded. Correspondingly, it leads to the problems of extended docking period and increased shipbuilding costs, and it is also impossible to determine whether the welding quality of the half ship meets the launching conditions. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a method for determining the welding amount of a half-ship floating and landing hull, evaluates the overall longitudinal strength and local strength of the half-ship, and reduces the amount of welding construction work before the half-ship is launched in the dock while fully ensuring that the strength of the half-ship meets the safety of the half-ship floating and landing operation, thereby creating conditions for the on-time delivery of the ship.

[0004] The present invention specifically adopts the following technical solutions:

[0005] A method for determining the welding amount of a half-ship floating landing hull comprises the following steps:

[0006] (1) Determine the half-ship welding operation area in the dock according to the half-ship structure and the segmentation form, and determine the half-ship floating draft requirements and cabin loading conditions; the half-ship welding operation area in the dock includes the plate closing seam area, the frame welding area, and the sudden change position where the rear section of the engine room cannot be completely closed;

[0007] (2) Based on the plate closure seam area determined in step (1), the overall longitudinal strength of the half-hull is evaluated on the basis that all welding of the plate closure seam area is completed;

[0008] (3) Based on the sudden change position where the tail section of the engine room cannot be completely closed determined in step (1), the local strength of the half-ship hull is evaluated;

[0009] (4) When the total longitudinal strength of the half-ship hull and the local strength of the half-ship hull in steps (2) and (3) both meet the design requirements, the longitudinal frame welding amount of the frame welding area is determined through step (5); if steps (2) and (3) cannot meet the design requirements, it is considered that the current construction state is not suitable for half-ship floating operation, and the loading compartment design plan or the half-ship closure state needs to be adjusted until the total longitudinal strength of the half-ship hull and the local strength of the half-ship hull in steps (2) and (3) both meet the design requirements, and then step (5) is executed;

[0010] (5) Calculate the required plate thickness of the ship's plane bulkhead plate, compare the actual plate thickness of the ship's plane bulkhead plate with the required plate thickness, and determine the longitudinal frame welding amount in the frame welding area.

[0011] In the above technical solution, adjusting the half-ship closed state refers to adding a half-ship ring segment in the cargo hold or removing part of the ring segment at the rear of the engine room.

[0012] Furthermore, the plate closing seam area in step (1) includes the closing welds between the platforms of the cabin section, the closing annular seams between the cabin and the cargo hold ring section, the closing annular seams between the cargo hold ring sections, the closing welds between the side sections and the middle deck sections, the transverse bulkhead sections and the double bottom sections, and the closing welds between the side decks and the side bilge sections.

[0013] Furthermore, the step (2) is specifically as follows:

[0014] (21) Determine the longitudinal strength assessment cross-sections for different areas of the half ship;

[0015] (22) Calculate the maximum actual longitudinal bending moment that the cross-sections in different regions of the half-ship can withstand, i.e., the actual longitudinal bending moment of the half-ship; and calculate the theoretical longitudinal bending moment that the cross-sections in different regions of the half-ship can withstand under the floating and landing conditions, i.e., the designed longitudinal bending moment of the half-ship;

[0016] (23) Calculate the maximum shear force that the cross-sections of different regions of the half-ship can actually withstand, i.e., the actual shear force of the half-ship; and calculate the theoretical shear force that the cross-sections of different regions of the half-ship can withstand under the floating and landing conditions, i.e., the design shear force of the half-ship;

[0017] (24) The calculated maximum longitudinal bending moment and shear force that the cross-sections in different areas of the half-ship can actually withstand are compared with the theoretical longitudinal bending moment and shear force that the cross-sections in different areas of the half-ship can withstand under floating and landing conditions to determine whether the actual longitudinal strength of the half-ship meets the requirements.

[0018] Furthermore, the calculation formula for the actual maximum tolerable total longitudinal bending moment of the cross-section of different regions of the half ship in step (22) is:

[0019] M=σ×Z X

[0020] Where, σ is the minimum allowable stress of the hull girder; Z X It is the smaller of the section modulus at the bottom and the section modulus at the deck.

[0021] Furthermore, in the step (22), the total longitudinal bending moment theoretically borne by the cross sections of different regions of the half-ship under the floating and landing conditions includes the hydrostatic bending moment of the half-ship and the wave bending moment of the half-ship. The hydrostatic bending moment of the half-ship and the wave bending moment of the half-ship of different cross sections are added together to obtain the total longitudinal bending moment theoretically borne by the cross sections of different regions of the half-ship under the floating and landing conditions.

[0022] The half-ship still water bending moment should be calculated according to the bending theory of straight beams;

[0023] The calculation formula for the wave bending moment at any longitudinal position of the half ship is:

[0024] Middle arch state:

[0025] M ωv-h =0.19f nl-vh f m f p C W L 2 BC B

[0026] Sagging state:

[0027] M ωυ-s =-0.19f nl-vs f m f p C W L 2 BC B

[0028] Among them, M ωυ-h is the wave bending moment in the mid-hogging state, M ων-s is the wave bending moment in the sagging state; f nl-vh f is the coefficient for considering the nonlinear effect of the centering camber; nl-vs f is the coefficient for considering the nonlinear effect on the sag; m is the distribution coefficient of vertical wave bending moment along the ship length; f p =f ps , f ps is the strength assessment coefficient corresponding to the applicable design load setting; C W is the wave coefficient; L is the length of the ship; B is the width of the ship; C B is the square coefficient.

[0029] Furthermore, in the step (23), the theoretical shear force borne by the cross-sections of different regions of the half-ship under the floating and landing conditions includes the hydrostatic shear force of the half-ship and the vertical wave shear force, and the hydrostatic shear force and the vertical wave shear force of the half-ship of different cross-sections are added together to obtain the theoretical shear force borne by the cross-sections of different regions of the half-ship under the floating and landing conditions;

[0030] The shear force in still water of half a ship should be calculated according to the bending theory of straight beams;

[0031] The calculation formula of vertical wave shear force at any longitudinal position of half ship is:

[0032] Positive wave shear:

[0033] Q ωυ-pos =0.52f q-pos f p C W LBC B

[0034] Negative wave shear:

[0035] Q ωυ-neg =-0.52f q-neg f p C W LBC B

[0036] Among them, f q-pos is the distribution coefficient of positive wave shear along the ship length; f q-neg is the distribution coefficient of negative wave shear along the ship length; f p =f os , f ps is the strength assessment coefficient corresponding to the applicable design load setting; C W is the wave coefficient; L is the length of the ship; B is the width of the ship; C B is the square coefficient.

[0037] Furthermore, the step (3) is specifically to use the finite element method to perform a local strength assessment on the mutation position where the tail section of the nacelle cannot be completely closed, including the steps of:

[0038] (31) According to the half-ship structure, a half-ship floating finite element model is established. The hull shell, cabin boundary, platform, longitudinal girder, main supporting member, hatch coaming web and hatch coaming panel are simulated with plate elements, and other frame materials are simulated with beam elements, and the grid is set;

[0039] (32) Setting the local strength verification load of the half-ship, including applying the half-ship gravity load, applying the seawater pressure on the outer plate area, and applying the ballast water gravity load on the cabin bottom plate in the stowage compartment;

[0040] (33) Setting the boundary conditions for the local strength verification of the half-ship, i.e., using the inertia release method, with the center of the outer bottom half-ship close to the midship position as the constraint point;

[0041] (34) The stress calculation results of plate units and beam units are analyzed by finite element simulation and compared with the allowable stress of the half-ship structure to determine whether the mutation position where the tail section of the engine room cannot be completely closed meets the requirements.

[0042] Furthermore, the step (5) is specifically as follows:

[0043] (51) Calculate the required plate thickness t of the ship's plane bulkhead plate to ensure that the actual plate thickness T of the ship's plane bulkhead plate satisfies T ≥ [t, 5.5] min. The calculation formula for the required plate thickness t of the ship's plane bulkhead plate is:

[0044]

[0045] Where, s is the spacing of stiffeners; h is half ship draft or ballast tank pressure head height, and 1 meter water pressure head is added to the design value as a safety margin. When the calculation target is the plate in contact with seawater, the h value is the draft; when the calculation target is the plate in contact with ballast water, the h value is the ballast tank pressure head height. ρ is the liquid density, t / m3, and the value should be not less than 1.025 during calculation; k is the material coefficient;

[0046] (52) According to the relationship between the required plate thickness of the ship's plane bulkhead plate and the required longitudinal frame welding amount, the required longitudinal frame welding amount corresponding to the required plate thickness of the ship's plane bulkhead plate closest to the actual plate thickness of the ship's plane bulkhead plate is selected as the longitudinal frame welding amount in the half-ship frame welding area.

[0047] The present invention has the following beneficial effects:

[0048] The present invention provides a method for determining the welding amount of a half-ship floating and landing hull, evaluates the total longitudinal strength and local strength of the half-ship, and on the premise of fully ensuring that the strength of the half-ship meets the safety of the half-ship floating and landing operation, reduces the welding construction workload before the half-ship is launched in the dock, improves the loading construction efficiency in the half-ship dock, provides a theoretical basis for the reasonable allocation of shipbuilding construction personnel, and creates conditions for the timely delivery of the ship; and the method of the present invention adopts a cross-section simplification method when evaluating the total longitudinal strength of the half-ship, which method can not only accurately perform strength calculations, but also improves calculation efficiency. In addition, the present invention also combines the finite element method to analyze and determine the local strength of the half-ship when performing strength evaluation, so as to ensure that the hull will not be deformed during the half-ship floating and landing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a flow chart of the present invention;

[0050] Figure 2 It is a schematic diagram of the half-ship structure of the present invention;

[0051] Figure 3 Calculate the model for the FR51 profile;

[0052] Figure 4 Simulated cloud map for local strength verification of half ship. DETAILED DESCRIPTION

[0053] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and specific examples.

[0054] Reference Figure 1 and Figure 2 This embodiment takes a 210,000-ton bulk carrier as an example. Its half-ship structure is a ring section from part of the engine room area to the cargo hold area. When the half-ship is floating, the average draft is about 3.24 meters, and the height of the cargo hold bottom plate from the load water in the cargo hold is about 2.80 meters. The welding amount of the half-ship floating pier hull is evaluated and determined, including the following steps:

[0055] (1) The half-ship welding operation area in the dock is determined according to the half-ship structure and the segmentation form, and the half-ship floating draft requirements and cabin loading conditions are determined; the half-ship welding operation area in the dock includes the plate closing seam area, the frame welding area, and the mutation position where the rear section of the engine room cannot be completely closed.

[0056] In this step, the half-ship structure includes the engine room area, the cargo hold area and the tail area, and the plate closing seam area includes the closing welds between the platforms of the engine room section, the closing ring seams between the engine room and the cargo hold ring section, the closing ring seams between the cargo hold ring sections, the closing welds between the side sections and the middle deck sections, the transverse bulkhead sections and the double bottom sections, and the closing welds between the side deck and the side bilge sections.

[0057] (2) Based on the plate closure seam area determined in step (1), the overall longitudinal strength of the half-hull is evaluated on the basis that all welding of the plate closure seam area is completed. Specifically:

[0058] (21) Determine the longitudinal strength assessment cross-sections for different areas of the half ship;

[0059] (22) Calculate the maximum actual longitudinal bending moment that the cross-sections in different regions of the half-ship can withstand, i.e., the actual longitudinal bending moment of the half-ship; and calculate the theoretical longitudinal bending moment that the cross-sections in different regions of the half-ship can withstand under the floating and landing conditions, i.e., the designed longitudinal bending moment of the half-ship;

[0060] (23) Calculate the maximum shear force that the cross-sections of different regions of the half-ship can actually withstand, i.e., the actual shear force of the half-ship; and calculate the theoretical shear force that the cross-sections of different regions of the half-ship can withstand under the floating and landing conditions, i.e., the design shear force of the half-ship;

[0061] (24) The calculated maximum longitudinal bending moment and shear force that the cross-sections in different areas of the half-ship can actually withstand are compared with the theoretical longitudinal bending moment and shear force that the cross-sections in different areas of the half-ship can withstand under floating and landing conditions to determine whether the actual longitudinal strength of the half-ship meets the requirements.

[0062] In this step, in the specific calculation process, due to the large number of closing seams, a typical cross section can be selected for evaluation according to the characteristics of the half-ship. Specifically, in the engine room area, when the engine room area of ​​the half-ship is complete, the middle cross section can be selected for calculation and evaluation; if part of the hull structure in the engine room area does not participate in the construction of the half-ship, a cross section close to the cargo hold area should be added on the basis of the above section for calculation and evaluation; in the cargo hold area, the cross section at the maximum position of the still water bending moment within the construction range of the half-ship is selected for calculation and evaluation; in the stern area, since the hull structure in the stern area is mostly located above the floating waterline of the half-ship, a cross section close to the engine room area (such as the rear wall area of ​​the engine room) can be selected for calculation and evaluation. In this embodiment, the FR51, FR45, FR30, and FR14 sections are selected for calculation.

[0063] Among them, the actual maximum tolerable total longitudinal bending moment of the cross-section in different areas of the half ship is calculated as follows:

[0064] According to the cross-sectional structure of different areas of the ship, the calculation model of different cross-sections is established using the calculation software specified by the classification society. The section modulus of each section is calculated by the established calculation model, and the smaller value of the section modulus at the bottom of the ship and the section modulus at the deck is selected during the calculation process to calculate the maximum total longitudinal bending moment that the cross-section of different areas of the half ship can withstand. According to the formula M = σ × Z X , the actual maximum tolerable total longitudinal bending moment of the cargo hold cross section is calculated. Taking the FR51 section as an example, Figure 3 The figure shows the cross-section calculation model of FR51. Through calculation, the cross-section modulus at the deck of FR51 is 3.662m. 3 The section modulus at the bottom of the ship is 5.315m 3 According to CCS Classification Society's "Rules for Classification of Seagoing Steel Ships", the minimum allowable bending stress of the hull beam is 105 / KN / mm 2 The minimum allowable bending stress at this section is 105 / k=105 / 0.72=145.8N / mm 2 Therefore, the maximum total longitudinal bending moment that the FR51 section can withstand is Mtotal51=3.662x145.8x1000=533919.6KN·m. The actual maximum total longitudinal bending moment that the FR51, FR45, FR30, and FR14 sections can withstand is shown in Table 1 below.

[0065] Table 1

[0066]

[0067]

[0068] The theoretical total longitudinal bending moment of the cross sections in different regions of the half-ship under the floating and pier-dropping condition is the designed total longitudinal bending moment. The theoretical total longitudinal bending moment includes the hydrostatic bending moment of the half-ship and the wave bending moment of the half-ship. The hydrostatic bending moment and the wave bending moment of the half-ship of different cross sections are added together to obtain the theoretical total longitudinal bending moment of the cross sections in different regions of the half-ship under the floating and pier-dropping condition. The calculation is as follows:

[0069] The half-ship hydrostatic bending moment is calculated by simulating the straight beam bending theory using the napa software. The calculation results of the FR51, FR45, FR30, and FR14 sections are shown in Table 2 below.

[0070] Table 2

[0071]

[0072] The calculation formula for the wave bending moment at any longitudinal position of the half ship is:

[0073] Middle arch state:

[0074] M ωυ-h =0.19f nl-vh f m f p C W L 2 BC B

[0075] Sagging state:

[0076] M ωυ-s =-0.19f nl-vs f m f p C W L 2 BC B

[0077] The wave bending moments at the longitudinal positions of the half-ship FR51, FR45, FR30, and FR14 sections calculated according to the above formula are shown in Table 3 below.

[0078] Table 3

[0079]

[0080] Thus, the theoretical total longitudinal bending moment, i.e., the design bending moment, of the half-ship FR51, FR45, FR30, and FR14 cross sections under the floating landing condition is obtained, as shown in Table 4 below.

[0081] Table 4

[0082]

[0083] The calculation process of the actual maximum tolerable shear force of the cross-section in different areas of the half ship is as follows:

[0084] For the ribs with complete ring segments, the longitudinally arranged components should ensure structural continuity, that is, to ensure the continuity of shear force in the transverse section. The shear components (inner longitudinal wall plates, longitudinal girders and outer plates) in the ring segments are welded completely. It is determined that the shear capacity of the half-ship floating state in the complete ring segment is basically consistent with the shear capacity of the whole ship, and the shear strength in the complete area of ​​the ring segment meets the requirements; for the ribs with incomplete ring segments, the shear capacity of the corresponding section is obtained by simulation calculation software specified by the classification society. The calculation model of shear capacity and Figure 3 The calculation model of the FR51 cross section shown in the figure is the same, and the section modulus and shear capacity can be calculated. The shear capacity of FR51 is calculated to be 75189KN. The actual maximum tolerable shear force of the FR51, FR45, FR30, and FR14 cross sections is shown in Table 5.

[0085] Table 5

[0086]

[0087] The theoretical shear force of the cross-sections in different areas of the half-ship under the floating and pier conditions is the design shear force. The theoretical shear force includes the hydrostatic shear force of the half-ship and the vertical wave shear force. The hydrostatic shear force and the vertical wave shear force of the half-ship in different cross-sections are added together to obtain the theoretical shear force of the cross-sections in different areas of the half-ship under the floating and pier conditions. The calculation process is as follows:

[0088] The hydrostatic shear force of the half-ship is calculated by simulating the bending theory of straight beams using the napa software. The hydrostatic shear force calculation results of the FR51, FR45, FR30, and FR14 sections are shown in Table 6 below.

[0089] Table 6

[0090]

[0091]

[0092] The calculation formula of vertical wave shear force at any longitudinal position of half ship is:

[0093] Q ωv-pos =0.52f q-pos f p C W LBC B

[0094] Q ωυ-neg =-0.52f q-neg f p C w LBCB

[0095] The vertical wave shear forces of the half-ship sections FR51, FR45, FR30, and FR14 calculated according to the above formula are shown in Table 7 below.

[0096] Table 7

[0097]

[0098] Thus, the theoretical shear force of the cross-section in different areas of the half ship under the floating pier condition, that is, the design shear force, is obtained, as shown in Table 8 below. It should be noted that in the calculation process, Q ωv-pos , Q ωv-neg The maximum absolute value of is calculated by superimposing it with the hydrostatic shear force.

[0099] Table 8

[0100]

[0101] The actual maximum longitudinal bending moment and shear force that the cross-sections in different areas of the half-ship calculated above can withstand are compared with the theoretical longitudinal bending moment and shear force that the cross-sections in different areas of the half-ship can withstand under the floating pier condition to determine whether the actual longitudinal strength of the half-ship meets the requirements. The verification results are shown in Tables 9 and 10 below, respectively, and the longitudinal strength meets the requirements.

[0102] Table 9 Summary of calculation results of total longitudinal bending moment

[0103]

[0104]

[0105] Table 10 Summary of shear force calculation results

[0106]

[0107] (3) Based on the mutation position where the tail section of the engine room cannot be completely closed determined in step (1), the local strength of the half-ship hull is evaluated.

[0108] This step specifically uses the finite element method to perform a local strength assessment on the mutation position where the tail section of the cabin cannot be completely closed, including the following steps:

[0109] (31) According to the half-ship structure, a half-ship floating finite element model is established. The hull shell, cabin boundary, platform, longitudinal girder, main supporting member, hatch coaming web and hatch coaming panel are simulated with plate elements, and other frame materials are simulated with beam elements, and the grid is set;

[0110] (32) Setting the local strength verification load of the half-ship, including applying the half-ship gravity load, applying the seawater pressure on the outer plate area, and applying the ballast water gravity load on the cabin bottom plate in the stowage compartment;

[0111] (33) Setting the boundary conditions for the local strength verification of the half-ship, i.e., using the inertia release method, with the center of the outer bottom half-ship close to the midship position as the constraint point;

[0112] (34) The stress calculation results of plate units and beam units are analyzed by finite element simulation and compared with the allowable stress of the half-ship structure to determine whether the mutation position where the tail section of the engine room cannot be completely closed meets the requirements.

[0113] In this embodiment, the local strength of the incomplete area of ​​the half ship ring section is specifically checked. The local strength check result is determined by the stress calculation results of the plate unit and the rod unit through finite element analysis and the allowable stress of the hull structure. The local strength check result of the half ship of a 210,000-ton bulk carrier is as follows: Figure 4 As shown, (a) and (b) are the stress calculation results of plate element and rod element respectively.

[0114] The stress calculation results of plate unit and rod unit by finite element analysis are compared with the allowable stress of hull structure, as shown in Table 11 below, which meets the requirements.

[0115] Table 11

[0116]

[0117] (4) The total longitudinal strength of the half-hull and the local strength of the half-hull in the above steps (2) and (3) meet the design requirements, and the longitudinal frame welding amount in the frame welding area is determined through step (5).

[0118] (5) Calculate the required plate thickness of the ship's plane bulkhead plate, and compare the actual plate thickness of the ship's plane bulkhead plate with the required plate thickness to determine the longitudinal frame welding amount in the frame welding area. This step is specifically as follows:

[0119] (51) Calculate the required plate thickness t of the ship's plane bulkhead plate to ensure that the actual plate thickness T of the ship's plane bulkhead plate satisfies T ≥ [t, 5.5] min. The calculation formula for the required plate thickness t of the ship's plane bulkhead plate is:

[0120]

[0121] Where, s is the spacing of stiffeners; h is half ship draft or ballast tank pressure head height, and 1 meter water pressure head is added to the design value as a safety margin. When the calculation target is the plate in contact with seawater, the h value is the draft; when the calculation target is the plate in contact with ballast water, the h value is the ballast tank pressure head height. ρ is the liquid density, t / m3, and the value should be not less than 1.025 during calculation; k is the material coefficient;

[0122] (52) According to the relationship between the required plate thickness of the ship's plane bulkhead plate in different areas and the required welding amount of longitudinal frame, the required plate thickness of the ship's plane bulkhead plate that is closest to the actual plate thickness of the ship's plane bulkhead plate is selected as the longitudinal frame welding amount in the half-ship frame welding area. The relationship between the required plate thickness of the outer bottom plate and the required welding amount of the longitudinal frame is shown in Table 12. Specifically, for the 210,000-ton bulk carrier of this embodiment, it is determined that the outer bottom plate area below 1m above the half-ship floating design draft is welded one frame at a time.

[0123] Table 12

[0124]

[0125] It should be noted that Table 12 is the conclusion drawn through statistical comparison, and the design verification is carried out with reference to the requirements of classification society rules for watertight bulkheads. The unwelded frames are regarded as failures. By comparing the required thickness of the outer plate with the actual outer plate thickness under the conditions of seawater pressure load in the floating state and different numbers of failed frames, the number of failed frames that can meet the local strength requirements is determined, and the minimum number of welds required for the frames is obtained.

[0126] Based on the above-mentioned frame welding, the frame strength of the outer bottom plate area is verified as shown in Table 13 below.

[0127] Table 13

[0128]

[0129] The calculation results in Table 13 show that the local strength of the aggregate meets the requirements under the above minimum number of aggregate welding.

[0130] Similarly, for other areas, the amount of frame welding in other areas is determined according to the relationship between the required plate thickness of different areas and the required longitudinal frame welding amount, so as to obtain the minimum frame welding amount of all half-ship frame welding areas. The frame welding amount determined in this embodiment is:

[0131] (1) The main plate welding at the ring segment annular seam is complete (including the double bottom longitudinal girder);

[0132] (2) In the outer bottom area below 1m above the half-ship floating design draft, one longitudinal frame is welded every other frame;

[0133] (3) In the ballast cargo hold bottom plate area, one longitudinal rib is welded every two ribs;

[0134] (4) In the sloping plating area of ​​the ballast cargo hold, one longitudinal rib is welded every two ribs;

[0135] (5) For the side plate frame below 1m above the half-floating design draft, one longitudinal frame is welded every two;

[0136] (6) Considering that the deck end is far away from the neutral axis of the transverse section and contributes greatly to the section modulus, it is recommended that the deck longitudinals, side shell longitudinals and top tank sloping plating longitudinals within 3m below the deck be welded every other longitudinal.

[0137] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for determining the welding amount of a half-ship floating landing hull, characterized in that: Includes steps: (1) Determine the half-ship welding operation area in the dock according to the half-ship structure and the segmentation form, and determine the half-ship floating draft requirements and cabin loading conditions; the half-ship welding operation area in the dock includes the plate closing seam area, the frame welding area, and the sudden change position where the rear section of the engine room cannot be completely closed; (2) Based on the plate closure seam area determined in step (1), the overall longitudinal strength of the half-hull is evaluated on the basis that all welding of the plate closure seam area is completed; (3) Based on the sudden change position where the tail section of the engine room cannot be completely closed determined in step (1), the local strength of the half-ship hull is evaluated; (4) When the total longitudinal strength of the half-ship hull and the local strength of the half-ship hull in steps (2) and (3) both meet the design requirements, the longitudinal frame welding amount of the frame welding area is determined through step (5). If steps (2) and (3) cannot meet the design requirements, it is considered that the current construction state is not suitable for half-ship floating operation, and the loading compartment design plan or the half-ship closure state needs to be adjusted. When the total longitudinal strength of the half-ship hull and the local strength of the half-ship hull in steps (2) and (3) both meet the design requirements, step (5) is executed; (5) Calculate the required plate thickness of the ship's plane bulkhead plate, compare the actual plate thickness of the ship's plane bulkhead plate with the required plate thickness, and determine the longitudinal frame welding amount in the frame welding area.

2. The method for determining the welding amount of a half-ship floating landing hull according to claim 1 is characterized in that: The plate closing seam area in step (1) includes the closing seams between the platforms of the cabin main section, the closing seams between the cabin and the cargo hold ring section, the closing seams between the cargo hold ring sections, the closing seams between the side sections and the middle deck sections, the transverse bulkhead sections and the double bottom sections, and the closing seams between the side decks and the side bilge sections.

3. The method for determining the welding amount of a half-ship floating landing hull according to claim 1 is characterized in that: The step (2) is specifically: (21) Determine the longitudinal strength assessment cross-sections for different areas of the half ship; (22) Calculate the actual maximum longitudinal bending moment that the cross-section of different regions of the half-ship can withstand, that is, the actual longitudinal bending moment of the half-ship; And calculate the theoretical total longitudinal bending moment of the cross sections in different areas of the half-ship under the floating landing condition, that is, the designed total longitudinal bending moment of the half-ship; (23) Calculate the maximum shear force that the cross-sections of different regions of the half-ship can actually withstand, i.e., the actual shear force of the half-ship; and calculate the theoretical shear force that the cross-sections of different regions of the half-ship can withstand under the floating and landing conditions, i.e., the design shear force of the half-ship; (24) The calculated maximum longitudinal bending moment and shear force that the cross-sections in different areas of the half-ship can actually withstand are compared with the theoretical longitudinal bending moment and shear force that the cross-sections in different areas of the half-ship can withstand under floating and landing conditions to determine whether the actual longitudinal strength of the half-ship meets the requirements.

4. The method for determining the welding amount of a half-ship floating landing hull according to claim 1 is characterized in that: The calculation formula for the actual maximum tolerable total longitudinal bending moment of the cross-sections of different regions of the half ship in step (22) is: M=σ×Z X Where, σ is the minimum allowable stress of the hull girder; Z X It is the smaller of the section modulus at the bottom and the section modulus at the deck.

5. The method for determining the welding amount of a half-ship floating landing hull according to claim 1 is characterized in that: In the step (22), the total longitudinal bending moment theoretically borne by the cross sections of different regions of the half-ship under the floating and landing conditions includes the hydrostatic bending moment of the half-ship and the wave bending moment of the half-ship. The hydrostatic bending moment of the half-ship and the wave bending moment of the half-ship of different cross sections are added together to obtain the total longitudinal bending moment theoretically borne by the cross sections of different regions of the half-ship under the floating and landing conditions. The half-ship still water bending moment should be calculated according to the bending theory of straight beams; The calculation formula for the wave bending moment at any longitudinal position of the half ship is: Middle arch state: M ωv-h =0.19f nl-vh f m f p C W L 2 BC B Sagging state: M ων-s =-0.19f nl-vs f m f p C W L 2 BC B Among them, M ων-h is the wave bending moment in the mid-hogging state, M ωv-s is the wave bending moment in the sagging state; f nl-vh f is the coefficient for considering the nonlinear effect of the centering arch; nl-vs f is the coefficient for considering the nonlinear effect on the sag; m is the distribution coefficient of vertical wave bending moment along the ship length; f p =f ps , f ps is the strength assessment coefficient corresponding to the applicable design load setting; C W is the wave coefficient; L is the length of the ship; B is the width of the ship; C B is the square coefficient.

6. The method for determining the welding amount of a half-ship floating pier according to claim 1 is characterized in that: In the step (23), the theoretical shear force borne by the cross sections of different regions of the half-ship under the floating and landing conditions includes the hydrostatic shear force of the half-ship and the vertical wave shear force. The hydrostatic shear force and the vertical wave shear force of the half-ship of different cross sections are added together to obtain the theoretical shear force borne by the cross sections of different regions of the half-ship under the floating and landing conditions. The shear force in still water of half a ship should be calculated according to the bending theory of straight beams; The calculation formula of vertical wave shear force at any longitudinal position of half ship is: Positive wave shear: Q ωυ-pos =0.52f q-pos f p C W LBC B Negative wave shear: Q ωυ-neg =-0.52f q-neg f p C W LBC B Among them, f q-pos is the distribution coefficient of positive wave shear along the ship length; f q-neg is the distribution coefficient of negative wave shear along the ship length; f p =f ps , f ps is the strength assessment coefficient corresponding to the applicable design load setting; C W is the wave coefficient; L is the length of the ship; B is the width of the ship; C B is the square coefficient.

7. The method for determining the welding amount of a half-ship floating pier according to claim 1 is characterized in that: The step (3) is specifically to use the finite element method to perform a local strength assessment on the mutation position where the tail section of the cabin cannot be completely closed, including the steps of: (31) According to the half-ship structure, a half-ship floating finite element model is established. The hull shell, cabin boundary, platform, longitudinal girder, main supporting member, hatch coaming web and hatch coaming panel are simulated with plate elements, and other frame materials are simulated with beam elements, and the grid is set; (32) Setting the local strength verification load of the half-ship, including applying the half-ship gravity load, applying the seawater pressure on the outer plate area, and applying the ballast water gravity load on the cabin bottom plate in the stowage compartment; (33) Setting the boundary conditions for the local strength verification of the half-ship, i.e., using the inertia release method, with the center of the outer bottom half-ship close to the midship position as the constraint point; (34) The stress calculation results of plate units and beam units are analyzed by finite element simulation and compared with the allowable stress of the half-ship structure to determine whether the mutation position where the tail section of the engine room cannot be completely closed meets the requirements.

8. The method for determining the welding amount of a half-ship floating pier according to claim 1 is characterized in that: The step (5) is specifically as follows: (51) Calculate the required plate thickness t of the ship's plane bulkhead plate to ensure that the actual plate thickness T of the ship's plane bulkhead plate satisfies T ≥ [t, 5.5] min. The calculation formula for the required plate thickness t of the ship's plane bulkhead plate is: Where, s is the spacing of stiffeners; h is half ship draft or ballast tank pressure head height, and 1 meter water pressure head is added to the design value as a safety margin. When the calculation target is the plate in contact with seawater, the h value is the draft; when the calculation target is the plate in contact with ballast water, the h value is the ballast tank pressure head height. ρ is the liquid density, t / m3, and the value should be not less than 1.025 during calculation; k is the material coefficient; (52) According to the relationship between the required plate thickness of the ship's plane bulkhead plate and the required longitudinal frame welding amount, the required longitudinal frame welding amount corresponding to the required plate thickness of the ship's plane bulkhead plate that is closest to the actual plate thickness of the ship's plane bulkhead plate is selected as the longitudinal frame welding amount in the half-ship frame welding area.

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