Direct prediction method for wave loads on crane vessels

Abstract

The present invention discloses a method for directly predicting wave loads for a crane vessel, which includes the following steps: establishing a hydrodynamic grid model, establishing a mass model with the weight distribution of the entire ship, and obtaining the velocity potential under regular waves through analytical calculation; using a mass decomposition method to obtain the virtual mass moment of inertia of the heavy object on the crane; rewriting the mass matrix equation; obtaining the inertial internal load by calculating the hydrodynamic force, and calculating the wave bending moment and wave shear force of the front section of the mass section as well as the frequency response function of the ship's motion and load; obtaining a response spectrum by setting short-term sea conditions and wave spectra, and using a spectral analysis method to perform a short-term prediction of the response spectrum; and then obtaining a long-term load extreme value prediction for the hull structure based on the probability distribution of each short-term sea condition within a long life cycle. The present invention successfully obtains the correct wave load for the crane vessel; and can also solve the problem of predicting wave loads for heavy objects that are not within the length of the ship.

Description

Technical Field

[0001] The present invention relates to the technical field of ships, and in particular to a method for directly predicting wave loads on crane ships. Background Art

[0002] With the continuous development of offshore oil and gas development and coastal and port engineering, the application of large crane vessels is gaining increasing attention. Crane vessels are engineering vessels primarily responsible for lifting offshore structures and are used for the installation and removal of large structures at sea. During the lifting process, the effects of cargo and wave loads must be considered. Due to the layout and function of crane vessels, their structural stress state differs significantly from that of conventional ships. Therefore, it is no longer reasonable to use classification society's standard load formulas to calculate and verify the structural strength of such vessels. Therefore, hydrodynamic methods must be used to predict the motion response and structural loads of such vessels, thereby conducting accurate structural strength analysis of crane vessels.

[0003] Existing, general methods for direct wave load prediction are based on three-dimensional potential flow theory and employ a three-dimensional panel-based hydrodynamic analysis method. The purpose of hydrodynamic analysis is to study the forces and motions of a ship in waves and evaluate its dynamic performance in waves. This analysis can reveal the pressure distribution on the wetted surface of the hull, the ship's motion in waves, and the wave loads at any cross-section.

[0004] Several issues in current hydrodynamic analysis:

[0005] 1. When a floating crane lifts a heavy object, the boom and the object extend beyond the hull. However, the mass matrix used in general hydrodynamic methods to calculate and predict the wave load on the hull is limited to the length of the hull itself, and no mass outside the hull is considered.

[0006] 2. The crane arm and load outside the hull length have a large mass and cannot be ignored. If they are ignored, the overall mass matrix will be incorrect, the solution of the ship motion will be wrong, and the subsequent wave load solution step will be meaningless.

[0007] 3. If the overall mass matrix includes heavy objects outside the hull, the hull motion and the seawater dynamic pressure on the hull's wet surface can be correctly solved; however, general hydrodynamic methods cannot take the segmented mass outside the ship's length, and a large part of the inertial load is lost. When calculating wave bending moment and shear force, the external seawater load and inertial force are ultimately unbalanced, resulting in the stern bending moment prediction result being significantly unable to return to zero at the bow (stern), and the result is obviously wrong.

[0008] 4. The frequency response function (RAO) results of ship motion and load are incorrect, which also leads to errors in subsequent long-term and short-term forecast results. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art and provide a method for directly predicting wave loads on crane vessels.

[0010] The present invention solves the above technical problems through the following technical solutions:

[0011] A method for directly predicting wave loads on a crane vessel comprises the following steps:

[0012] Step 1: Establish a hydrodynamic grid model and a mass model with the weight distribution of the entire ship. Through analytical calculation, obtain the velocity potential under regular waves.

[0013] Step 2, using the mass decomposition method to obtain the virtual mass moment of inertia of the heavy object hoisted outside the range of the ship length;

[0014] Step 3: Rewrite the mass matrix equation. First, remove the weight distribution outside the ship length range and add the virtual weight calculated by the decomposition mass method. The mass matrix of a section within the ship length range can be written as:

[0015]

[0016] Among them, M' ref is the total weight from the stern to the section. If this section passes through the virtual mass point, the virtual mass is included;

[0017]

[0018] Ma is the mass distribution point of the entire ship within the length of the ship, M i is a virtual mass point;

[0019] X ref =X pou -X G ,

[0020] Among them, X pou is the X coordinate of the mass at a certain point on the section (including the virtual mass point), X G is the X coordinate of the center of gravity of the entire ship;

[0021] Y ref =Y pou -Y G ,

[0022] Among them, Y pou is the Y coordinate of a point on the section (including virtual mass points), G is the Y coordinate of the center of gravity of the entire ship;

[0023] Z ref =Z pou -Z G ,

[0024] Among them, Z pou is the Z coordinate of a point on the section (including virtual mass points), Z G is the Z coordinate of the center of gravity of the entire ship;

[0025] Among them, I' 45 , I' 56 , I' 46 Small, can be ignored as 0;

[0026]

[0027]

[0028]

[0029] Step 4: Based on the rewritten mass matrix equation, the inertial internal load is obtained by calculating the hydrodynamic force, and the wave bending moment and wave shear force of the front section of the mass section as well as the frequency response function of the ship motion and load are calculated;

[0030] Step 5: Based on the obtained frequency response function of ship motion and load, wave bending moment and wave shear force, the response spectrum is obtained by setting the short-term sea conditions and wave spectrum, and the response spectrum is predicted in the short term using the spectrum analysis method; then, based on the probability distribution of each short-term sea condition in the long life cycle, the long-term load extreme value prediction of the hull structure is obtained.

[0031] In step 1, the calculation formula of the regular wave is:

[0032] ζ=ζ a cos(kx-ωt);

[0033] Where: ζ is the wavefront rise; a is the amplitude; k is the wave number; ω is the circular frequency.

[0034] In step 1, the velocity potential of the regular wave is:

[0035]

[0036] Where: g is the acceleration due to gravity and z is the vertical position.

[0037] In step 2, the mass decomposition method is specifically as follows: decompose the heavy object outside the range of the ship length into several sub-masses so that they are within the range of the ship length, the mass point is located at the base of the lifting system, and the virtual mass moment of inertia of the heavy object is obtained by the static balance method.

[0038] The calculation formula of the static balance method is:

[0039] Mg=m1g+m2g+m3g;

[0040] MgR=m1gr1+m2gr2+m3gr3;

[0041] Where: M is the mass of the weight, R' is the distance from the center of gravity of the weight to the center of gravity axis of the whole ship, R is the lever arm from the center of gravity of the weight to the center of gravity of the whole ship, m1 is the partial mass at base 1, r1 is the lever arm from base 1 to the center of gravity of the whole ship, m2 is the partial mass at base 2, r2 is the lever arm from base 2 to the center of gravity of the whole ship, m3 is the partial mass at base 3, r3 is the lever arm from base 3 to the center of gravity of the whole ship.

[0042] The mass moment of inertia of the hoisted object about the ship's centroidal axis is:

[0043] MR ’2 =MR 2 α 2

[0044] MR ’2 =(m1r1+m2r2+m3r3)α 2 R;

[0045] Wherein, α=R′ / R.

[0046] If there are n bases on the hull, then:

[0047]

[0048]

[0049]

[0050] In step 4, the hydrodynamic calculation uses the ship motion equation, which is:

[0051]

[0052] in:

[0053] M jk is the generalized mass matrix term, which is the mass matrix obtained in step 2;

[0054] A jk ,B jk ,C jk are the additional mass coefficient, damping coefficient, and restoring coefficient of the jth degree of freedom caused by the motion of the kth degree of freedom, collectively referred to as the hydrodynamic coefficient;

[0055] F j is the wave force on the hull in the direction of the jth degree of freedom;

[0056] η k , are the displacement, velocity and acceleration of the kth degree of freedom motion respectively.

[0057] In step 4, the method for calculating the frequency response function of the ship motion and load is as follows: within the complete frequency range of the wave encounter frequency, take 20 to 30 frequencies, select several wave directions within the entire wave direction range, and perform regular wave motion response calculation for each wave direction and frequency combination to obtain the frequency response function of the ship motion and load.

[0058] In step 4, the wave bending moment and wave shear force of the front section of the mass section can be calculated by the inertial force and fluid dynamics acting on the hull.

[0059] In step 5, the response spectrum S R (ω) and wave spectrum S ζ The relationship between (ω) is:

[0060] S R (ω)=RAO(ω) 2 ·S ζ (ω).

[0061] The beneficial effects of the present invention are as follows: the method of the present invention establishes a mass model with the weight distribution of the entire ship by establishing a hydrodynamic grid model, and obtains the velocity potential under regular waves through three-dimensional diffraction and radiation analysis calculations; and obtains the wave bending moment and shear force by solving the motion equation and the dynamic balance equation. The important innovation of the method of the present invention is that it adopts a mass decomposition method, rewrites the mass matrix equation, and solves the dynamic balance calculation. The method of the present invention simulates the weight of the hoisted object by decomposing it into virtual mass, distributing it within the length of the ship, and simulating the distributed full-ship mass matrix along the length of the ship, thereby achieving a realistic mass distribution effect along the length of the ship, and ensuring the balance between the external load of seawater dynamic pressure and the internal load of inertia force when calculating wave bending moment and shear force. The method of the present invention adopts a mass decomposition matrix method to decompose the outboard weight so that it is within the length of the ship, rewrites the segmented mass matrix along the length of the ship of the general hydrodynamic method, unifies the total mass matrix and the segmented mass matrix, overcomes the limitation that the general hydrodynamic program cannot be applied to the wave load prediction of the crane vessel, and has great application and promotion value. The method of the present invention solves the problem that existing hydrodynamic methods cannot obtain the correct wave load under the lifting condition of the crane ship; the correct wave load of the crane ship is successfully obtained; the present invention can also solve the problem of wave load prediction when heavy objects are not within the length of the ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a schematic diagram of a crane vessel lifting heavy objects according to a preferred embodiment of the present invention.

[0063] Figure 2 This is a mass decomposition diagram of a crane vessel lifting a heavy object according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0064] A preferred embodiment is given below and the present invention is described more clearly and completely in conjunction with the accompanying drawings.

[0065] A method for directly predicting wave loads on a crane vessel includes the following steps.

[0066] Step 1: Establish a hydrodynamic grid model and a mass model with the weight distribution of the entire ship. Through analytical calculation, the velocity potential is obtained under regular waves.

[0067] In step 1, the calculation formula of the regular wave is:

[0068] ζ=ζ a cos(kx-ωt);

[0069] Where: ζ is the wavefront rise; a is the amplitude; k is the wave number; ω is the circular frequency.

[0070] In step 1, the velocity potential of the regular wave is:

[0071]

[0072] Where: g is the acceleration due to gravity and z is the vertical position.

[0073] Step 2: Use the mass decomposition method to obtain the virtual mass moment of inertia of the heavy object hoisted outside the length of the ship.

[0074] In step 2, the mass decomposition method is specifically as follows: decompose the heavy object outside the range of the ship length into several sub-masses so that they are within the range of the ship length, the mass point is located at the base of the lifting system, and the virtual mass moment of inertia of the heavy object is obtained by the static balance method.

[0075] like Figure 1 As shown, in a crane ship, a lifting system 20 is connected to the hull 10. The lifting system 20 itself cannot rotate, and the lifting system 20 lifts a heavy object 30 over the side of the ship. The lifting system 20 and the hull 10 have three connection bases, namely a first base 21, a second base 22 and a third base 23.

[0076] Since the weight and mass moment of inertia of the heavy object 30 outside the ship length need to be taken into account, the heavy object must first be decomposed into several sub-masses so that they are within the ship length, with the mass points located at the base of the heavy crane. Figure 1 , the mass M of the weight 30 is decomposed into a partial mass m1 at the first base 21 , a partial mass m2 at the second base 22 , and a partial mass m3 at the third base 23 .

[0077] It should be noted that Figure 1In the figure, the partial mass m1 at the first base 21, the partial mass m2 at the second base 22, and the partial mass m3 at the third base 23 do not exist in the real object. There is only the weight 30 in the real object. In order to show the theoretical decomposition of the weight 30 into the first base 21, the second base 22, and the third base 23, Figure 1 The weight 30 and the divided masses m1, m2, and m3 are displayed simultaneously.

[0078] The solution to the problem of decomposing the mass into several components so that it is within the range of the ship's length should meet the following conditions: the height of the decomposed mass point is consistent with the height of the center of gravity of the entire ship; the buoyancy of the hull remains unchanged, that is, the results of calculating the buoyancy of the hull using the decomposed mass and calculating the buoyancy of the hull using the hanging weight are consistent.

[0079] Figure 1 The mass decomposition diagram of the structure shown is as follows: Figure 2 shown.

[0080] like Figure 2 As shown, because the floating state has not changed and the external load of seawater has not changed, the decomposed mass replaces the mass of the heavy object, which will inevitably produce a balanced force system.

[0081] The calculation formula of the static balance method is:

[0082] Mg=m1g+m2g+m3g;

[0083] MgR=m1gr1+m2gr2+m3gr3;

[0084] Where: M is the mass of the weight, R' is the distance from the center of gravity of the weight to the center of gravity axis of the whole ship, R is the lever arm from the center of gravity of the weight to the center of gravity of the whole ship, m1 is the partial mass at the first base, r1 is the lever arm from the first base to the center of gravity of the whole ship, m2 is the partial mass at the second base, r2 is the lever arm from the second base to the center of gravity of the whole ship, m3 is the partial mass at the third base, and r3 is the lever arm from the third base to the center of gravity of the whole ship.

[0085] The above can be simplified to:

[0086] M=m1+m2+m3;

[0087] MR=m1r1+m2r2+m3r3;

[0088] The additional condition for solving m1, m2, and m3 is that the buoyancy of the hull remains unchanged, which can be obtained using the hydrostatic curve method and will not be repeated here.

[0089] The mass moment of inertia of the hoisted object about the ship's centroidal axis is:

[0090] MR ’2 =MR 2 α 2 ;

[0091] MR ’2 =(m1r1+m2r2+m3r3)α 2 R;

[0092] Wherein, α=R′ / R.

[0093] If there are n bases on the hull, then:

[0094]

[0095]

[0096]

[0097] Step 3: Rewrite the mass matrix equation. First, remove the weight distribution outside the ship length range and add the virtual weight calculated by the decomposition mass method. The mass matrix of a section within the ship length range can be written as:

[0098]

[0099] Among them, M' ref is the total weight from the stern to the section. If this section passes through the virtual mass point, the virtual mass is included;

[0100]

[0101] Ma is the mass distribution point of the entire ship within the length of the ship, M i is a virtual mass point.

[0102] X ref =X pou -X G ,

[0103] Among them, X pou is the X coordinate of the mass at a certain point on the section (including the virtual mass point), X G is the X coordinate of the center of gravity of the entire ship;

[0104] Y ref =Y pou -Y G ,

[0105] Among them, Y pou is the Y coordinate of a point on the section (including virtual mass points), G is the Y coordinate of the center of gravity of the entire ship;

[0106] Z ref =Z pou -Z G ,

[0107] Among them, Zpou is the Z coordinate of a point on the section (including virtual mass points), Z G is the Z coordinate of the center of gravity of the entire ship;

[0108] Among them, I' 45 , I' 56 , I' 46 Small, can be ignored as 0;

[0109] The mass inertia moment I' generated by the actual lifting weight on the center of gravity of the entire ship 55 , should be:

[0110] MR ’2 =(m1r1+m2r2+m3r3)α 2 R.

[0111] Through mass decomposition, the decomposed mass moment of inertia generated by general hydrodynamic software is:

[0112] m1r1 2 +m2r2 2 +m3r3 2 .

[0113] Therefore, if the mass decomposition method is applied in general hydrodynamic software, the mass matrix generated is inconsistent with the mass moment of inertia generated by the actual weight, which is wrong and must be modified. 44 , I' 55 , I' 66 For example, the vertical wave bending moment that we are most concerned about needs to be modified I' 55 , directly in the section passing through the virtual mass point, modify the increase in its mass moment of inertia, integrate from the stern to the bow, and at the bow section position of the final integration, keep the total mass moment of inertia generated by the ship's outboard weight equal to the mass moment of inertia generated by the virtual decomposition mass, I' 44 , I' 66 The modification method is similar.

[0114]

[0115]

[0116]

[0117] Step 4: Based on the rewritten mass matrix equation, the inertial internal load is obtained by calculating the hydrodynamic force, and the wave bending moment and wave shear force of the front section of the mass section as well as the frequency response function of the ship motion and load are calculated.

[0118] In step 4, the hydrodynamic calculation uses the ship motion equation, which is:

[0119]

[0120] in:

[0121] M jk is the generalized mass matrix term, which is the mass matrix obtained in step 2;

[0122] A jk ,B jk ,C jk are the additional mass coefficient, damping coefficient, and restoring coefficient of the jth degree of freedom caused by the motion of the kth degree of freedom, collectively referred to as the hydrodynamic coefficient;

[0123] F j is the wave force on the hull in the direction of the jth degree of freedom;

[0124] η k , are the displacement, velocity and acceleration of the kth degree of freedom motion respectively.

[0125] In step 4, the method for calculating the frequency response function of the ship motion and load is as follows: within the complete frequency range of the wave encounter frequency, take 20 to 30 frequencies, select several wave directions within the entire wave direction range, and perform regular wave motion response calculation for each wave direction and frequency combination to obtain the frequency response function of the ship motion and load.

[0126] In step 4, the wave bending moment and wave shear force of the front section of the mass section can be calculated by the inertial force and fluid dynamics acting on the hull.

[0127] Step 5: Based on the obtained frequency response function of ship motion and load, wave bending moment and wave shear force, the response spectrum is obtained by setting the short-term sea conditions and wave spectrum, and the response spectrum is predicted in the short term using the spectrum analysis method; then, based on the probability distribution of each short-term sea condition in the long life cycle, the long-term load extreme value prediction of the hull structure is obtained.

[0128] In step 5, the response spectrum S R (ω) and wave spectrum S ζ The relationship between (ω) is:

[0129] S R (ω)=RAO(ω) 2 ·S ζ (ω).

[0130] The method of the present invention establishes a hydrodynamic grid model and a mass model with the weight distribution of the entire ship. Through three-dimensional diffraction and radiation analysis and calculation, the velocity potential is obtained under regular waves. The wave bending moment and shear force are obtained by solving the equation of motion and the dynamic equilibrium equation.

[0131] The important innovation of the method of the present invention is that it adopts a mass decomposition method, rewrites the mass matrix equation, and solves the dynamic balance calculation.

[0132] The method of the present invention simulates the weight of the lifted object by decomposing the mass into virtual mass, distributes it within the length of the ship, and simulates the mass matrix of the entire ship along the length of the ship after distribution, thereby achieving a realistic mass distribution effect along the length of the ship. In addition, when calculating the wave bending moment and shear force, the balance between the external load of the seawater dynamic pressure and the internal load of the inertia force is ensured.

[0133] The method of the present invention adopts the method of decomposing the mass matrix. By using this method, the outboard weight is decomposed so that it is within the range of the ship length, the segmented mass matrix along the ship length of the general hydrodynamic method is rewritten, the total mass matrix and the segmented mass matrix are unified, and the limitation that the general hydrodynamic program cannot be applied to the wave load prediction of the crane vessel is overcome. It has great application and promotion value!

[0134] The method of the present invention solves the problem that existing hydrodynamic methods cannot obtain the correct wave load under the lifting condition of the crane ship; the correct wave load of the crane ship is successfully obtained; the present invention can also solve the problem of wave load prediction when heavy objects are not within the length of the ship.

[0135] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A method for direct prediction of wave loads on crane vessels, characterized in that: It includes the following steps: Step 1: Establish a hydrodynamic grid model and a mass model with the weight distribution of the entire ship. Through analytical calculation, obtain the velocity potential under regular waves. Step 2, using the mass decomposition method to obtain the virtual mass moment of inertia of the heavy object hoisted outside the range of the ship length; Step 3: Rewrite the mass matrix equation. First, remove the weight distribution outside the ship length range and add the virtual weight calculated by the decomposition mass method. The mass matrix of a section within the ship length range can be written as: Among them, M' ref is the total weight from the stern to the section. If this section passes through the virtual mass point, the virtual mass is included; Ma i is the mass distribution point of the entire ship within the length of the ship, M i is a virtual mass point; X ref =X pou -X G , Among them, X pou is the X coordinate of the mass at a certain point on the section, X G is the X coordinate of the center of gravity of the entire ship; AND ref =And pou -AND G , Among them, Y pou is the Y coordinate of the mass of a point on the section, G is the Y coordinate of the center of gravity of the entire ship; WITH ref =Z pou -WITH G , Among them, Z pou is the mass Z coordinate of a point on the section, Z G is the Z coordinate of the center of gravity of the entire ship; Among them, I' 45 , I' 56 , I' 46 If it is smaller, it is considered as 0; Step 4: Based on the rewritten mass matrix equation, the inertial internal load is obtained by calculating the hydrodynamic force, and the wave bending moment and wave shear force of the front section of the mass section as well as the frequency response function of the ship motion and load are calculated; Step 5: Based on the obtained frequency response function of ship motion and load, wave bending moment and wave shear force, the response spectrum is obtained by setting the short-term sea conditions and wave spectrum, and the response spectrum is predicted in the short term using the spectrum analysis method; then, based on the probability distribution of each short-term sea condition in the long life cycle, the long-term load extreme value prediction of the hull structure is obtained.

2. The method for direct prediction of wave loads on a crane vessel according to claim 1, wherein: In step 1, the calculation formula of the regular wave is: g=g a cos(kx-ωt); Where: ζ is the wavefront rise; a is the amplitude; k is the wave number; ω is the circular frequency.

3. The method for direct prediction of wave loads on a crane vessel according to claim 2, wherein: In step 1, the velocity potential of the regular wave is: Where: g is the acceleration due to gravity and z is the vertical position.

4. The method for direct prediction of wave loads for a crane vessel according to claim 1, characterized in that: In step 2, the mass decomposition method is specifically as follows: decompose the heavy object outside the range of the ship length into several sub-masses so that they are within the range of the ship length, the mass point is located at the base of the lifting system, and the virtual mass moment of inertia of the heavy object is obtained by the static balance method.

5. The method for direct prediction of wave loads on a crane vessel according to claim 4, characterized in that: The calculation formula of the static balance method is: Mg=m1g+m2g+m3g; MgR=m1gr1+m2gr2+m3gr3; Where: M is the mass of the weight, R is the lever arm from the center of gravity of the weight to the center of gravity of the entire ship, m1 is the partial mass at base 1, r1 is the lever arm from base 1 to the center of gravity of the entire ship, m2 is the partial mass at base 2, r2 is the lever arm from base 2 to the center of gravity of the entire ship, m3 is the partial mass at base 3, r3 is the lever arm from base 3 to the center of gravity of the entire ship.

6. The method for direct prediction of wave loads for a crane vessel according to claim 5, characterized in that: The mass moment of inertia of the hoisted object about the ship's centroidal axis is: MR’ 2 =MR 2 α 2 ; MR’ 2 =(m1r1+m2r2+m3r3)α 2 R; Wherein, α=R' / R; R' is the distance from the center of gravity of the weight to the center of gravity axis of the entire ship.

7. The method for direct prediction of wave loads on a crane vessel according to claim 6, characterized in that: If there are n bases on the hull, then:

8. The method for direct prediction of wave loads for a crane vessel according to claim 1, characterized in that: In step 4, the hydrodynamic calculation uses the ship motion equation, which is: in: M jk is the generalized mass matrix term, which is the mass matrix obtained in step 2; A jk ,B jk ,C jk are the additional mass coefficient, damping coefficient, and restoring coefficient of the jth degree of freedom caused by the motion of the kth degree of freedom, collectively referred to as the hydrodynamic coefficient; F j is the wave force on the hull in the direction of the jth degree of freedom; η k , are the displacement, velocity and acceleration of the kth degree of freedom motion respectively.

9. The method for direct prediction of wave loads for a crane vessel according to claim 8, characterized in that: In step 4, the method for calculating the frequency response function of the ship motion and load is as follows: within the complete frequency range of the wave encounter frequency, take 20 to 30 frequencies, select several wave directions within the entire wave direction range, and for each wave direction and frequency combination, perform regular wave motion response calculation to obtain the frequency response function of the ship motion and load.

10. The method for direct prediction of wave loads on a crane vessel according to claim 9, characterized in that: In step 4, the wave bending moment and wave shear force of the front section of the mass section are calculated by the inertial force and fluid dynamics acting on the hull.

11. The method for direct prediction of wave loads on a crane vessel according to claim 1, wherein: In step 5, the response spectrum S R (ω) and wave spectrum S ζ The relationship between (ω) is: S R (ω)=RAO(ω) 2 ·S ζ (oh)。

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