CN103076394A - Safety evaluation method for ocean platform based on integration of vibration identification frequencies and vibration mode - Google Patents

Abstract

The invention discloses a safety evaluation method for an ocean platform based on integration of vibration identification frequencies and a vibration mode. The method comprises: step one, establishing a finite element model with an undamaged structure to serve as a reference finite element model; performing vibration tests to the undamaged structure, and identifying modal frequencies omega di (i=1,..., m) of front m stages and a vibration mode of the undamaged structure to serve as actual measured modal parameters; and evaluating a whole safety state of a service damaged platform structure. According to the method, safety evaluation of a platform structure can be performed directly on the basis of diagnosis vibration test data identification structure parameter definition and safety evaluation parameters, the problem that structural damage diagnosis and safety evaluation of actual engineering structures are difficult in a structural damage diagnosis method based on vibration detection combination is solved; defects that environmental excitation, noise effects and complete measurement effects are large of conventional methods in actual engineering application are overcome; and the method has the advantages that the computational efficiency is high, the applicability is high, the physical significance is explicit, and the like.

Description

Method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape

Technical field

The present invention relates to the method for offshore platform structure man-rate, relate in particular to a kind of method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape.Belong to the Offshore Engineering field.

Background technology

Offshore platform structure is the great basic facility of offshore petroleum resources exploitation, simultaneously, also is the base of offshore production operation and life.The offshore platform structure long service in abominable marine environment, fatigue load long terms such as wind-engaging, wave and stream simultaneously, the drag decay is very obvious.Damage not only can cause great economic loss and casualties in case have an accident, and also may cause the impact of serious environmental pollution and society and politics.Therefore, offshore platform structure is monitored, detected and evaluate its security, guarantee that the security of its operation is very necessary.

In order to grasp the safety case of offshore platform structure, at first must carry out Non-Destructive Testing to it.

The method of existing Non-Destructive Testing mainly comprises: range estimation, Ultrasonic Detection, magnetic, acoustic emission (FMD) etc., and these detect the method that all belongs to the structure partial damage check; Be characterized in to detect local damage and also require special testing apparatus and professional and technical personnel.Therefore, these methods are not too convenient to the detection of ocean platform, and testing cost is expensive.

Deficiency for existing structure lossless detection method existence, recent development based on the portable lossless detection method of vibration-testing, this method is simple, cost is lower, simultaneously can computation structure Integral modes parameter, that is: frequency and the vibration shape according to the acceleration information of vibration-testing.But, also need pass through the parameter recognition technology based on the man-rate of this detection method, and position and the degree of the damage of integrated structure damage diagnosis method recognition structure, carry out the finite element model correction, and on this basis, carry out again the structural safety evaluation.And mainly contain based on the Structural Damage Identification of finite element model: based on the Structural Damage Identification of residual force vector, feature to Sensitivity Method, stress energy method etc., wherein, Structural Damage Identification based on the residual force vector is to go out to send to damage identification from the residual force equation, when obtaining the residual force vector, need the complete vibration shape, then must carry out model polycondensation or mode shape expansion for measuring incomplete situation.Feature is the structural vibration equation have been made the linear process of first approximation to Sensitivity Method (frequency or the vibration shape) in essence, by one order (feature is to the derivative to the structural unit parameter) equation solution degree of injury.Stress energy method is that the quadratic form of the vibration shape and structural unit stiffness matrix is defined as the unit strain energy, the variation maximum of its strain energy of unit of damage occurs, accordingly, just damage position can be judged, degree of injury can be found the solution by the sensitivity of analyzing strain energy again.A common feature of above-mentioned these methods is to use the complete vibration shape and complete measurement, otherwise, need carry out model polycondensation or mode shape expansion.Because the error that model polycondensation or mode shape expansion bring, so, the precision of Damage Assessment Method reduced.

At present, owing to being subjected to the artificial excitation to implement relatively the restriction that the large and complete measurement measuring point of difficulty, neighbourhood noise is arranged the factor affecting such as difficulty relatively, carrying out the diagnosis of structural damage based on the vibration detection data and in Practical Project, use also very difficult.

Summary of the invention

Fundamental purpose of the present invention is to overcome the above-mentioned shortcoming that prior art exists, and provide a kind of method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape, it can directly based on diagnosing the definition of vibration detection data identification structural parameters and man-rate parameter to carry out the man-rate of platform structure, solve based on the diagnosing structural damage that is difficult in the vibration detection integrated structure damage diagnosis method carry out and engineering structure man-rate hard problem; Having overcome routine is subjected to environmental excitation, noise effect, complete measurement to affect large deficiency in practical engineering application based on vibration detection damage Safety Assessment Methods; Simultaneously, need to detect the situation of maintenance for the at present a large amount of ocean platforms of China, have broad application prospects and practical value.

The objective of the invention is to be realized by following technical scheme:

A kind of method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape is characterized in that: adopt following steps:

The first step: set up the not finite element model of damaged structure, as benchmark finite element structure model;

Second step: damaged structure is carried out vibration-testing, the front m rank model frequency ω of identification of damage structure _Di(i=1 ..., m) and the vibration shape

, as the actual measurement modal parameter;

The 3rd step: the general safety state to the damage platform structure of being on active service is evaluated.

In the described first step, benchmark finite element structure model represents with K and M, that is: the not stiffness matrix of damaged structure and the not mass matrix of damaged structure, and its list of feature values is shown

$K{\mathrm{\Φ}}_i={\mathrm{\ω}}_i^{2}M{\mathrm{\Φ}}_i$

Wherein, ω _iAnd Φ _iBe respectively i order frequency and the vibration shape of benchmark finite element structure model.

In the described second step, the m rank model frequency of identification of damage structure Concrete steps are as follows:

(1), utilize the structural dynamic response data behind the sensor measurement damage of structural object, and data are stored in the storer;

(2), from storer, read the acceleration information of storage, utilize Modal Parameters Identification to identify its limited lower mode frequency as the damaged structure model frequency

In described the 3rd step, the concrete steps of the general safety state evaluation of the damage platform structure of being on active service are:

⑴ adopt the method for compute mode degree of confidence matrix to choose the n first order mode as suitable modal parameter;

⑵ with the damaged structure Index Definition be: the damage platform structure n first order mode broad sense of being on active service rigidity and the rate of change that does not damage platform structure n first order mode broad sense rigidity that is to say:

$D=1-\frac{K_{\mathrm{dn}}}{K_{\mathrm{fn}}}---\left(1\right)$

Wherein: K _DnBe damaged structure n first order mode broad sense rigidity, K _FnFor not damaging platform structure n first order mode broad sense rigidity;

According to the structural natural frequencies Computing Principle, can get K through arrangement _DnAnd K _FnBe respectively:

$K_{\mathrm{dn}}={\mathrm{\ω}}_{\mathrm{dn}}^2{M}_{\mathrm{dn}}---\left(2a\right)$

$K_{\mathrm{fn}}={\mathrm{\ω}}_{\mathrm{fn}}^2{M}_{\mathrm{fn}}---\left(2b\right)$

ω in the formula _DnAnd ω _FnRespectively damage platform structure and the n stage structure natural frequency of not damaging platform structure; M _DnAnd M _FnBe respectively damaged structure and structure generalized mass corresponding to damaged structure n first order mode not, can calculate according to following formula respectively:

In the formula:

With

Be respectively the damage platform structure and do not damage the mass matrix of platform structure, can carry out mass matrix according to the limited element calculation model that equipment, structural change (mass change) data in design, manufacturing and installation (DFI) data of structure and the platform military service process are set up platform structure and extract acquisition; When use procedure does not have equipment, structural change (mass change), then With

Equate;

With Be respectively the n first order mode that damages platform structure and do not damage platform structure; Can be respectively to the damage platform structure with do not damage platform structure and carry out vibration-testing, and carry out the recognition of vibration acquisition according to the vibration-testing data.

Described platform structure man-rate characteristic parameter selection principle is:

⑴ when platform structure is intact when not damaging, the K of platform structure _D1And K _F1Equate, the platform and integrally damage index equals zero;

⑵ when platform structure damages when serious, the K of platform structure _D1Then less, the platform and integrally damage index is then larger;

⑶ platform structure integrated carrying ability and structural entity rigidity are closely related, when platform structure is local when damage occurring, and platform structure stiffness degradation that then should the part, thus the integral rigidity of platform structure reduces, and therefore, structural-load-carrying capacity also reduces;

⑷ according to the whole damage index computing formula of platform structure, structural entity stiffness variation as can be known, and then the whole damage index of platform structure also changes thereupon;

By above-mentioned platform structure damage index computation process as can be known, platform structure the first rank natural frequency that relates to and the vibration shape can obtain by its test data identification by arrange acceleration transducer at platform;

By above-mentioned platform structure damage index computation process as can be known, all intermediate parameters that relate to can be by calculate obtaining.

Beneficial effect of the present invention: the present invention is owing to adopting technique scheme, it can directly based on diagnosing the definition of vibration detection data identification structural parameters and man-rate parameter to carry out the man-rate of platform structure, solve based on being difficult to carry out diagnosing structural damage and engineering structure man-rate hard problem in the vibration detection integrated structure damage diagnosis method; Having overcome routine is subjected to environmental excitation, noise effect, complete measurement to affect large deficiency in practical engineering application based on vibration detection damage Safety Assessment Methods; Have the characteristics such as counting yield is high, applicability strong, explicit physical meaning; And principle is simple, calculating is quick, practicality is good; Simultaneously, need to detect the situation of maintenance for the at present a large amount of ocean platforms of China, have broad application prospects and practical value, particularly cooperate the portable vibration rapid detection system to promote.

Description of drawings:

Fig. 1 is structural representation of the present invention.

Fig. 2 is platform structure elevation drawing of the present invention.

Fig. 3 is platform structure finite element model of the present invention.

Fig. 4 is the last first order mode that benchmark model of the present invention calculates.

Fig. 5 is the front second_mode that benchmark model of the present invention calculates.

Fig. 6 is first three first order mode that benchmark model of the present invention calculates.

Fig. 7 is the front quadravalence vibration shape that benchmark model of the present invention calculates.

Fig. 8 is the first five first order mode that benchmark model of the present invention calculates.

Fig. 9 is vibration monitoring of engineering structure sensor arrangenent diagram of the present invention.

Figure 10 is the last first order mode of on-the-spot test identification of the present invention.

Figure 11 is the front second_mode of on-the-spot test identification of the present invention.

Figure 12 is first three first order mode of on-the-spot test identification of the present invention.

Figure 13 is the front quadravalence vibration shape of on-the-spot test identification of the present invention.

Figure 14 is the first five first order mode of on-the-spot test identification of the present invention.

Embodiment

Such as Fig. 1, shown in Figure 2, the present invention adopts following steps:

The first step: set up the not finite element model of damaged structure, as benchmark finite element structure model;

Second step: damaged structure is carried out vibration-testing, the front m rank model frequency ω of identification of damage structure _Di(i=1 ..., m) and the vibration shape , as the actual measurement modal parameter;

The 3rd step: the general safety state to the damage platform structure of being on active service is evaluated.

In the above-mentioned first step, benchmark finite element structure model represents with K and M, that is: the not stiffness matrix of damaged structure and the not mass matrix of damaged structure, and its list of feature values is shown

$K{\mathrm{\Φ}}_i={\mathrm{\ω}}_i^{2}M{\mathrm{\Φ}}_i$

Wherein, ω _iAnd Φ _iBe respectively i order frequency and the vibration shape of benchmark finite element structure model.

In the above-mentioned second step, the m rank model frequency of identification of damage structure

Concrete steps are as follows:

(1), utilize the structural dynamic response data behind the sensor measurement damage of structural object, and data are stored in the storer;

(2), from storer, read the acceleration information of storage, utilize Modal Parameters Identification to identify its limited lower mode frequency as the damaged structure model frequency

With Mode Shape φ _Di

One, the specific algorithm in above-mentioned the 3rd step is derived as follows:

In order to guarantee that assessment parameters can well be applied to engineering structure, in conjunction with the platform structure mechanical characteristics with based on the actual demand of vibration detection platform structure man-rate, the damage platform structure man-rate characteristic parameter selection principle of determining to be on active service is as follows:

1) definition of characteristic parameter has clear and definite physical significance;

2) variation of the variation of characteristic parameter energy reaction structure load-bearing capacity or the variation of the rigidity of structure;

3) the related intermediate parameters of calculation of characteristic parameters can both be calculated by the vibration detection data and obtain;

4) calculating of characteristic parameter is through having actual operability, and succinct as far as possible.

Follow mentioned above principle, the concrete steps of the general safety state evaluation of the damage platform structure of being on active service are:

1. at first, adopt the method for compute mode degree of confidence matrix to choose the n first order mode as suitable modal parameter;

2. with the damaged structure Index Definition be: the whole damage index of definition platform structure is platform structure man-rate characteristic parameter.The whole damage index of platform structure is defined as: the damage platform structure n first order mode broad sense of being on active service rigidity and the rate of change that does not damage platform structure first vibration mode broad sense rigidity that is to say:

$D=1-\frac{K_{\mathrm{dn}}}{K_{\mathrm{fn}}}---\left(1\right)$

Wherein: K _DnBe damaged structure n first order mode broad sense rigidity, K _FnFor not damaging platform structure n first order mode broad sense rigidity;

According to the structural natural frequencies Computing Principle, can get K through arrangement _DnAnd K _FnBe respectively:

$K_{\mathrm{dn}}={\mathrm{\ω}}_{\mathrm{dn}}^2{M}_{\mathrm{dn}}---\left(2a\right)$

$K_{\mathrm{fn}}={\mathrm{\ω}}_{\mathrm{fn}}^2{M}_{\mathrm{fn}}---\left(2b\right)$

ω in the formula _DnAnd ω _FnRespectively damage platform structure and the n stage structure natural frequency of not damaging platform structure; M _DnAnd M _FnBe respectively damaged structure and structure generalized mass corresponding to damaged structure n first order mode not, can calculate according to following formula respectively:

In the formula: With

Be respectively the damage platform structure and do not damage the mass matrix of platform structure, can carry out mass matrix according to the limited element calculation model that equipment, structural change (mass change) data in design, manufacturing and installation (DFI) data of structure and the platform military service process are set up platform structure and extract acquisition; When use procedure does not have equipment, structural change (mass change), then

With

Equate.

With

Be respectively the n first order mode of damage platform structure and intact platform structure; Can be respectively to the damage platform structure with do not damage platform structure and carry out vibration-testing, and carry out the recognition of vibration acquisition according to the vibration-testing data.

By definition and the computation process thereof of above-mentioned platform structure damage index, it meets platform structure man-rate characteristic parameter selection principle as can be known: at first, when platform structure is intact when not damaging, the K of platform structure _D1And K _F1Equate, the platform and integrally damage index equals zero; When platform structure damages when serious the K of platform structure _D1Then less, the platform and integrally damage index is then larger; Secondly, platform structure integrated carrying ability and structural entity rigidity are closely related, when platform structure is local when damage occurring, and platform structure stiffness degradation that then should the part, thereby, the integral rigidity reduction of platform structure, therefore, structural-load-carrying capacity also reduces; Simultaneously, according to the whole damage index computing formula of platform structure, structural entity stiffness variation as can be known, then the whole damage index of platform structure also changes thereupon.Next, by above-mentioned platform structure damage index computation process as can be known, platform structure the first rank natural frequency that relates to and the vibration shape can obtain by its test data identification by arrange acceleration transducer at platform.At last, by above-mentioned platform structure damage index computation process as can be known, all intermediate parameters that relate to all can obtain by calculating, and computation process is simple.

In order to carry out the structural safety evaluation according to damage index, with reference to building structure to the damaged structure safe class criteria for classifying, to damage the ocean platform integral structural safety and be classified as level Four, that is: A level, B level, C level, D level, grade scales at different levels and processing requirements are as follows:

The A level: the platform structure general safety meets safety standard to the requirement of A level, and structure is substantially intact, and damage even there is damage not affect total bearing capacity, may not have individual components to take measures yet;

The B level: the platform structure overall security is a little less than the requirement of safety standard to the A level, and structure has slight damage, but these damage not appreciable impact total bearing capacity, may have the only a few member to take measures;

The C level: the platform structure overall security fails safety standards to the requirement of A level, and structure has moderate lesion, and the appreciable impact total bearing capacity should be taken measures, and may have the minority member to take immediate steps;

The D level: the platform structure overall security utmost point fails safety standards to the requirement of A level, and structure has major injury, has a strong impact on total bearing capacity, must take immediate steps.

With reference to building structure seismic Damage the experimental results, determined offshore platform structure system safety classification standard, the result lists table 1 in.

Table 1 is based on the structural system safety classification standard of platform and integrally damage index

The A level	The B level	The C level	The D level
				D s＞0.05	0.15＞D s≥0.05	0.3＞D s≥0.15	D s≥3.0

Two, set up the jacket platform structural finite element model

As shown in Figures 2 and 3, this example is numbered the JZ20-2MUQ platform as example take oil field, the Bohai Sea, and this platform bottom is four leg's jackets, superstructure: be provided with deck of cellar, deck of sub-cellar, main deck, deckhead.The top layer deck is provided with the three layers of house in a building, and the house top is helideck.Utilize FEM software (Ansys) to set up benchmark finite element structure model, and according to newly-built structure real measured data correction benchmark finite element structure model as the benchmark finite element structure model of damaged structure not.According to the benchmark finite element structure model of model extraction structure with

With

Expression, that is: the stiffness matrix of damaged structure not

The mass matrix of damaged structure not

, and i order frequency and the vibration shape ω of calculating benchmark finite element structure model _FiAnd φ _Fi, the first five order frequency is listed table 2 and table 3 in, front 5 first order modes such as Fig. 4-and shown in Figure 8.

The first five rank model frequency that table 2 baseline finite element model calculates

The mode order	1	2	3	4	5
						Frequency (Hz)	0.9003	0.9936	1.064	1.615	1.651

The first five first order mode mode of table 3 benchmark finite element structure model extraction

This platform does not have new platform friction information state, but, this platform has carried out respectively on-the-spot test at 1994 and 2011, the result of twice test identification lists table 4 in, and the structure frequency difference of twice measurement identification is very little as can be known according to the result in the table 4, can think structure in-service because maintenance and inspection work is done and obtained bit architecture and damage do not occur, therefore, can be used for the model correction with the result that measured in 1994 as initial intact structure actual frequency, set up baseline finite element model.

First three order frequency frequency (Hz) of table 4 structure

Three, actual catheter body panel vibration monitoring of engineering structure and Modal Parameter Identification

The vibration-testing measuring point is arranged near near the aisle, jacket platform band hurdle four and the deck of cellar four main key pile nodes, amounts to 8 point positions, and 8 sensors are installed altogether, and the sensor arrangement as shown in Figure 9.This on-the-spot vibration-testing collects altogether mass data and is used for the structural modal computational analysis, and the first five rank model frequency of identification is listed table 5 in, the first five first order mode of identification such as Figure 10-and shown in Figure 14, and list table 6 in.Therefrom can find out, the 1st first order mode is the y direction, and existence is reversed; The 2nd first order mode is the x direction, has twisted coupling; The 3rd first order mode is torsion mode; The 4th first order mode is the x direction, the complete mode of second order; The 5th first order mode is the y direction, the complete mode of second order.

The first five rank model frequency (Hz) of each segment data identification of table 5

Mode	The 1st segment data	The 2nd segment data	The 3rd segment data	The 4th segment data	Average
						1	0.8994	0.889	0.8949	0.907	0.8976
2	1.0444	1.035	1.0279	1.058	1.0413
						3	1.1368	1.145	1.1898	1.181	1.1631
4	2.9520	2.932	2.9779	2.931	2.9482
						5	3.0579	3.043	3.0641	3.068	3.0582

The first five first order mode mode of table 6 identification

Four, jacket platform structural entity man-rate

In order directly to use frequency and the vibration shape of measuring point metrical information identification in 2012, carry out corresponding degree of freedom vibration shape extraction based on the test measuring point to revising finite element model, the result lists table 3 in.Extract vibration shape compute mode degree of confidence matrix (listing table 7 in) can to get the second-order recognition result be the most believable vibration shape according to measuring the identification vibration shape and finite element model, therefore, adopt structure second frequency and second vibration mode to come the whole damage index of computation structure.Because measuring is not complete measurement, therefore, carry out the polycondensation of corresponding degree of freedom based on measuring point information to revising finite element model, that is to say: polycondensation is the structure of 24 degree of freedom of 8 nodes, obtain 24 and take advantage of the mass matrix on 24 rank, therefore during this period not significantly change of architecture quality, adopts the whole damage index of identical mass matrix computation structure.The whole damage index of definition according to the present invention, in conjunction with the result of calculation of relevant parameter, the whole damage index that can calculate this structure is 0.033.According to the structural system safety classification standard based on the platform and integrally damage index, structure platform structural entity security compliance safety standard is to the requirement of A level as can be known, structure is substantially intact, and not damage is even may there be individual components to exist damage also not affect total bearing capacity.Do not find damage according to Local Quantitative testing result discovery structure, the result is basically identical with man-rate.

Table 7 modal assurance criterion matrix

The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, every foundation technical spirit of the present invention all still belongs in the scope of technical solution of the present invention any simple modification, equivalent variations and modification that above embodiment does.

Claims (5)

1. method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape is characterized in that: adopt following steps:

The first step: set up the not finite element model of damaged structure, as benchmark finite element structure model;

Second step: damaged structure is carried out vibration-testing, the front m rank model frequency ω of identification of damage structure _Di(i=1 ..., m) and the vibration shape

, as the actual measurement modal parameter;

The 3rd step: the general safety state to the damage platform structure of being on active service is evaluated.

2. the method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape according to claim 1, it is characterized in that: in the described first step, benchmark finite element structure model represents with K and M, that is: the not stiffness matrix of damaged structure and the not mass matrix of damaged structure, its list of feature values is shown

$K{\mathrm{\Φ}}_i={\mathrm{\ω}}_i^{2}M{\mathrm{\Φ}}_i$

Wherein, ω _iAnd Φ _iBe respectively i order frequency and the vibration shape of benchmark finite element structure model.

3. the method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape according to claim 1 is characterized in that: in the described second step, and the m rank model frequency of identification of damage structure

Concrete steps are as follows:

(1), utilize the structural dynamic response data behind the sensor measurement damage of structural object, and data are stored in the storer;

(2), from storer, read the acceleration information of storage, utilize Modal Parameters Identification to identify its limited lower mode frequency as the damaged structure model frequency

4. the method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape according to claim 1, it is characterized in that: in described the 3rd step, the concrete steps of the general safety state evaluation of the damage platform structure of being on active service are:

⑴ adopt the method for compute mode degree of confidence matrix to choose the n first order mode as suitable modal parameter;

⑵ with the damaged structure Index Definition be: the damage platform structure n first order mode broad sense of being on active service rigidity and the rate of change that does not damage platform structure n first order mode broad sense rigidity that is to say:

$D=1-\frac{K_{\mathrm{dn}}}{K_{\mathrm{fn}}}---\left(1\right)$

Wherein: K _DnBe damaged structure n first order mode broad sense rigidity, K _FnFor not damaging platform structure n first order mode broad sense rigidity;

According to the structural natural frequencies Computing Principle, can get K through arrangement _DnAnd K _FnBe respectively:

$K_{\mathrm{dn}}={\mathrm{\ω}}_{\mathrm{dn}}^2{M}_{\mathrm{dn}}---\left(2a\right)$

$K_{\mathrm{fn}}={\mathrm{\ω}}_{\mathrm{fn}}^2{M}_{\mathrm{fn}}---\left(2b\right)$

ω in the formula _DnAnd ω _FnRespectively damage platform structure and the n stage structure natural frequency of not damaging platform structure; M _DnAnd M _FnBe respectively damaged structure and structure generalized mass corresponding to damaged structure n first order mode not, can calculate according to following formula respectively:

In the formula:

With

Be respectively the damage platform structure and do not damage the mass matrix of platform structure, can carry out mass matrix according to the limited element calculation model that equipment, structural change (mass change) data in design, manufacturing and installation (DFI) data of structure and the platform military service process are set up platform structure and extract acquisition; When use procedure does not have equipment, structural change (mass change), then

With

Equate;

With Be respectively the n first order mode that damages platform structure and do not damage platform structure; Can be respectively to the damage platform structure with do not damage platform structure and carry out vibration-testing, and carry out the recognition of vibration acquisition according to the vibration-testing data.

5. the method based on the comprehensive ocean platform man-rate of Vibration identification frequency and the vibration shape according to claim 4, it is characterized in that: described platform structure man-rate characteristic parameter selection principle is:

⑴ when platform structure is intact when not damaging, the K of platform structure _D1And K _F1Equate, the platform and integrally damage index equals zero;

⑵ when platform structure damages when serious, the K of platform structure _D1Then less, the platform and integrally damage index is then larger;

⑶ platform structure integrated carrying ability and structural entity rigidity are closely related, when platform structure is local when damage occurring, and platform structure stiffness degradation that then should the part, thus the integral rigidity of platform structure reduces, and therefore, structural-load-carrying capacity also reduces;

⑷ according to the whole damage index computing formula of platform structure, structural entity stiffness variation as can be known, and then the whole damage index of platform structure also changes thereupon;

By above-mentioned platform structure damage index computation process as can be known, platform structure the first rank natural frequency that relates to and the vibration shape can obtain by its test data identification by arrange acceleration transducer at platform;

By above-mentioned platform structure damage index computation process as can be known, all intermediate parameters that relate to can be by calculate obtaining.

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