CN106896156A - By cross uniform load face curvature difference girder construction damnification recognition method - Google Patents

Abstract

The invention discloses a kind of girder construction damnification recognition method of face curvature of uniform load by cross difference, step is as follows：Frequency and the vibration shape before and after being damaged by girder construction calculate flexibility matrix；It is each to girder construction to be multiplied load is poor with the flexibility matrix before and after structural damage across applying uniform load by cross, obtain displacement difference；Damage criterion takes the absolute value sum of each across uniform load effect bottom offset difference curvature；It is assumed that moment of flexure is constant under girder construction damages front and rear load action；Moment of flexure change and displacement curvature estimation Joint Damage degree before and after being damaged according to girder construction, and then computing unit degree of injury；If girder construction is redundant structure, after the unit degree of injury and FEM model of previous step calculating obtain damaging front and rear moment of flexure change, repeats a previous step and obtain final unit degree of injury.The present invention effectively increases the ability of flexibility of curvature index damage reason location, and can exactly carry out damage extent identification, can preferably be applied to the Non-Destructive Testing of girder construction.

Description

By cross uniform load face curvature difference girder construction damnification recognition method

Technical field

The invention belongs to structural health monitoring technology field, be related to girder construction Dynamic Non-Destruction Measurement, and in particular to it is a kind of by The girder construction damnification recognition method of across uniform load face curvature difference.

Background technology

Damage Assessment Method is the important component of bridge health monitoring system, the damage based on structural dynamic response Hinder the focus that recognition methods is Recent study.Structural damage will cause the decline of the rigidity of structure, and then cause structural modal (to shake Dynamic frequency and the vibration shape) change, it is to study relatively early that damage check is carried out using frequency and the vibration shape, using more method.So And frequency and the vibration shape be not also to the sensitiveness of structural damage it is very high, it is many more sensitive based on the vibration shape or frequency and the vibration shape Index is proposed and for damage check, such as more change ratio of application, Modal Flexibility difference by researcher.Due to Modal Flexibility Sensitivity to damaging is far above frequency and the vibration shape, and relatively accurately can be built from several low-frequency vibration mode of structure It is vertical, therefore the method based on Modal Flexibility turns into a class important method in Damage Assessment Method.

The flexibility damage criterion of early stage, such as Modal Flexibility are poor, Modal Flexibility rate of change, point out to damage in the way of maximum Hinder position, the desired value of non-damage position is also larger, for panels with multiple site damage, recognition effect is undesirable, and many scholars are to base afterwards Studied in the index of flexibility of curvature, index, non-destructive tests are constructed after seeking curvature by some way to flexibility matrix Effect is improved.Tang little Bing etc. has carried out cantilever beam and simply supported girder bridge using the curvature of the maximum column element of Structure Flexibility Matrix Non-destructive tests numerical analysis.Cao Shuidong etc. is using the poor main diagonal element of the flexibility matrix before and after structural damage, computation structure Flexibility of curvature, and take with calculated by the use of the main diagonal element of flexibility matrix before structural damage obtained by flexibility of curvature ratio as Signatures for damage detection.Cao Hui etc. first sought the curvature matrix of Modal Flexibility before and after damaging before modulus state Flexibility Difference, used flexibility Curvature difference rectangular array vector maximization establishes modal flexibility curvature index.Yao Jingchuan etc. proposes On Modal Flexibility Curvature rate of change Structural Damage Identification.Li Yongmei etc. is proposed using the flexibility matrix before and after structural damage, successively to flexibility matrix difference Row, column carries out difference twice, tries to achieve curvature of the flexibility difference matrix matrix, and using its row maximum or diagonal element as detection structural damage Refer to calibration method.Xu's allusion quotation etc. proposes a kind of first calculating respectively and damages front and rear flexibility of curvature matrix maximum, then the damage for making the difference Distinguishing indexes.Zhang and Aktan proposes index of the uniform load face curvature difference as damage check, and the index will first be damaged respectively Each row of flexibility matrix before and after wound is added together, then seeks the curvature difference of the two column vectors, obtains the desired value of each node, thing Reason clear, but can not well be used for continuous beam damage check.

The content of the invention

The present invention can not preferably be used for the damage reason location of multispan girder construction for existing On Modal Flexibility Curvature damage criterion, And the problem of damage extent identification can not be carried out, there is provided a kind of girder construction non-destructive tests side of the face curvature of uniform load by cross difference Method.

The girder construction damnification recognition method of the difference of uniform load face curvature by cross of the invention, comprises the following steps：

(1) obtain the modal parameter before and after girder construction is damaged respectively by test, flexibility is calculated by frequency and the vibration shape respectively Matrix；

(2) it is each to girder construction across uniform load is applied by cross, uniform load and girder construction are damaged into front and rear flexibility matrix Difference is multiplied, and obtains corresponding displacement difference；

(3) the i-th across uniform load P is taken_iDisplacement difference curvature under effect is load P_iDamage criterion, final damage reason location Index takes the absolute value sum of the lower damage criterion of each across uniform load effect；

(4) assume that the Bending moment distribution that girder construction is damaged under front and rear uniform load effect does not change；

(5) moment of flexure change and displacement curvature estimation Joint Damage degree before and after being damaged according to girder construction, and then calculate To unit degree of injury；

(6) if girder construction is redundant structure, the unit degree of injury that step (5) is obtained is input to girder construction finite element In model, the Bending moment distribution situation of change under uniform load effect before and after girder construction is damaged is calculated, repeat step (5) is obtained Final unit degree of injury.

Specifically, step (1) center sill structure damage before and after modal parameters test, respectively across measure-point amount be no less than 8, and And point position arrangement is identical before and after damaging.

Specifically, the rank number of mode that test is obtained in step (1) is no less than 3 ranks.

Specifically, the method that modal parameters test use can survey excitation in step (1), directly measures and returns on mass matrix One vibration shape changed, or use only measures the method for output and the FEM model by girder construction sets up mass matrix, will shake After type is normalized to mass matrix, the Modal Flexibility matrix F represented using frequency and the vibration shape can be obtained：

Wherein, Φ=[φ₁,φ₂,L,φ_m] it is vibration shape matrix, m is nominal modes, φ_i=[φ_i1 φ_i2 L φ_in]^TFor I-th first order mode vector, n is measure-point amount,It is diagonal matrix, ω_iIt is the i-th rank circular frequency.

Specifically, the flexibility matrix difference before and after step (2) center sill structure is damaged is Δ：

Δ=F_u-F_d

Wherein, F_uAnd F_dFront and rear flexibility matrix is respectively damaged, subscript " u ", " d " represent non-faulted condition respectively in text And faulted condition；

By the equation of static equilibrium of structure：

W=[w (1) w (2) L w (n)]^T=FP

Wherein, w is motion vector, and w (x) is the element value of the xth position in w, and P is load column vector；

For N across (N >=1) girder construction, by across N number of uniform load vector is taken, to any uniform load P therein_i, its work Damaging front and rear displacement difference with lower beam structure is：

δw_i=w_ui-w_di=F_u·P_i-F_d·P_i=Δ P_i

Wherein, w_ui、w_diRespectively uniform load P_iEffect lower beam structure damages front and rear displacement.

Specifically, in step (3), the i-th across uniform load P_iCorresponding damage criterion is：

ULSC_i=δ w_i"=(Δ P_i)″

Wherein, subscript i is measuring point number, and δ l are the spacing and measuring point i to the average of measuring point i+1 spacing of measuring point i-1 to measuring point i Value；

Final damage criterion takes the absolute value sum of the lower damage criterion of each across uniform load effect：

Wherein, IULSC is final damage criterion, and N is girder construction across number.

Further, in step (3), uniform load P_iUsing unit force uniform load, i.e.,：

Wherein,For i-th is vectorial across the unit uniform load of loading, other are 0 vector.

Specifically, in step (5), Joint Damage degree is calculated using equation below：

Wherein：

Wherein, M_u(x)、M_dX () represents the moment of flexure that girder construction x position is damaged under front and rear uniform load effect, w respectively_ui″ (x)、w_di" (x) is respectively uniform load P_iEffect lower beam structure damage before and after x position displacement curvature, N for girder construction across Number.

Further, value of the Joint Damage degree being calculated in step (5) less than 0 is set to 0.

Further, unit degree of injury is calculated using equation below in step (5)：

Wherein, D_eX () is x position unit degree of injury, D_nX () is x position Joint Damage degree.

The present invention is loaded for multispan girder construction using uniform load by cross, is calculated each across uniform load effect Under damage criterion, final damage criterion takes the absolute value sum of each across uniform load loading damage criterion.The method effectively subtracts Lack multispan beam structural displacement diagram flex point number, because each across uniform load effect bottom offset knee of curve position is different, therefore energy The influence of displacement curve flex point is effectively shielded from, the deficiency of uniform load face curvature difference method is theoretically overcome, effectively Improve the ability of index damage reason location.And the unit degree of injury computational methods based on new method are proposed, can be accurate Degree of injury to girder construction is identified, for girder construction Non-Destructive Testing provides a kind of effective new method with assessment.

Brief description of the drawings

Fig. 1 is the FB(flow block) of the inventive method.

Fig. 2 is that invention unit is damaged and Joint Damage graph of a relation.

Fig. 3 is three-span continuous beam FEM model figure in the embodiment of the present invention.

Fig. 4 is the first across uniform load P in the embodiment of the present invention₁Figure.

Fig. 5 is the second across uniform load P in the embodiment of the present invention₂Figure.

Fig. 6 is the 3rd across uniform load P in the embodiment of the present invention₃Figure.

Fig. 7 is uniform load P by cross in the embodiment of the present invention_iDisplacement diagram.

Fig. 8 is uniform load P in the embodiment of the present invention₁Bending moment diagram.

Fig. 9 is uniform load P in the embodiment of the present invention₂Bending moment diagram.

Figure 10 is uniform load P in the embodiment of the present invention₃Bending moment diagram.

Figure 11 is operating mode 1IULSC index non-destructive tests result figures in the embodiment of the present invention.

Figure 12 is operating mode 2IULSC index non-destructive tests result figures in the embodiment of the present invention.

Figure 13 is operating mode 3IULSC index non-destructive tests result figures in the embodiment of the present invention.

Figure 14 is operating mode 3ULSC index non-destructive tests result figures in the embodiment of the present invention.

Figure 15 is operating mode 1IULSC index Joint Damage degree recognition result figures in the embodiment of the present invention.

Figure 16 is operating mode 2IULSC index Joint Damage degree recognition result figures in the embodiment of the present invention.

Figure 17 is operating mode 3IULSC index Joint Damage degree recognition result figures in the embodiment of the present invention.

Figure 18 is operating mode 3ULSC index Joint Damage degree recognition result figures in the embodiment of the present invention.

Figure 19 is operating mode 1IULSC index unit damage extent identification result figures in the embodiment of the present invention.

Figure 20 is operating mode 2IULSC index unit damage extent identification result figures in the embodiment of the present invention.

Figure 21 is operating mode 3IULSC index unit damage extent identification result figures in the embodiment of the present invention.

Figure 22 is that operating mode 1 damages front and rear moment of flexure variation diagram in the embodiment of the present invention.

Figure 23 is that operating mode 2 damages front and rear moment of flexure variation diagram in the embodiment of the present invention.

Figure 24 is that operating mode 3 damages front and rear moment of flexure variation diagram in the embodiment of the present invention.

Figure 25 is operating mode 1IULSC indexs consideration moment of flexure change unit damage extent identification result figure in the embodiment of the present invention.

Figure 26 is operating mode 2IULSC indexs consideration moment of flexure change unit damage extent identification result figure in the embodiment of the present invention.

Figure 27 is operating mode 3IULSC indexs consideration moment of flexure change unit damage extent identification result figure in the embodiment of the present invention.

Figure 28 is flexibility matrix error and rank number of mode graph of a relation in the embodiment of the present invention.

Specific embodiment

With reference to embodiment and accompanying drawing, the present invention is described in further detail.In the following description when referring to the accompanying drawings, Unless otherwise indicated, the same numbers of different accompanying drawings represent same or analogous key element.

It is the FB(flow block) of the girder construction damnification recognition method of the difference of uniform load face curvature by cross of the invention referring to Fig. 1, its Comprise the following steps that：

Step 1：Obtain the modal parameter before and after girder construction is damaged respectively by test, calculate soft respectively by frequency and the vibration shape Degree matrix.

Step 2：To girder construction respectively across uniform load is applied by cross, uniform load and girder construction are damaged into front and rear flexibility square Battle array difference is multiplied, and obtains corresponding displacement difference.

Step 3：Take the i-th across uniform load P_iDisplacement difference curvature under effect is load P_iDamage criterion, it is final to damage fixed Position index takes the absolute value sum of the lower damage criterion of each across uniform load effect.

Step 4：It is assumed that the Bending moment distribution that girder construction is damaged under front and rear uniform load effect does not change.

Step 5：Moment of flexure change and displacement curvature estimation Joint Damage degree before and after being damaged according to girder construction, and then calculate Obtain unit degree of injury；

Step 6：If girder construction is redundant structure, it is limited that the unit degree of injury that step 5 is obtained is input to girder construction In meta-model, the Bending moment distribution situation of change under uniform load effect before and after girder construction is damaged is calculated, repeat step 5 is obtained Final unit degree of injury.

Specifically, step 1 center sill structure damage before and after modal parameters test it is each across measure-point amount be no less than 8, and Point position arrangement is identical before and after damaging.

The rank number of mode that acquisition is tested in step 1 is no less than 3 ranks.

The method that modal parameters test use can survey excitation in step 1, directly measures and shake on mass matrix is normalized Type, or use only measures the method for output and the FEM model by girder construction sets up mass matrix, by the vibration shape to quality After matrix normalization, the Modal Flexibility matrix F represented using frequency and the vibration shape can be obtained：

Wherein, Φ=[φ₁,φ₂,L,φ_m] it is vibration shape matrix, m is nominal modes, φ_i=[φ_i1 φ_i2 L φ_in]^TFor I-th first order mode vector, n is measure-point amount,It is diagonal matrix, ω_iIt is the i-th rank circular frequency.

Specifically, the flexibility matrix difference before and after step 2 center sill structure is damaged is Δ：

Δ=F_u-F_d (2)

Wherein, F_uAnd F_dFront and rear flexibility matrix is respectively damaged, subscript " u ", " d " represent non-faulted condition respectively in text And faulted condition.

Element f in flexibility matrix F_ijRepresent in j measuring point function unit power, the deformation values of i measuring points, in the effect of j measuring points During unit force, the deformation values of other each measuring points are the jth row of flexibility matrix：

By the equation of static equilibrium of structure：

W=[w (1) w (2) L w (n)]^T=FP (5)

Wherein, w is motion vector, and w (x) is the element value of the xth position in w, and P is load column vector.

For N across (N >=1) girder construction, by across N number of uniform load vector is taken, to any uniform load P therein_i, its work Damaging front and rear displacement difference with lower beam structure is：

δw_i=w_ui-w_di=F_u·P_i-F_d·P_i=Δ P_i (6)

Wherein, w_ui、w_diRespectively uniform load P_iEffect lower beam structure damages front and rear displacement.

Specifically, across the uniform load P of step 3 i-th_iCorresponding damage criterion is：

ULSC_i=δ w_i"=(Δ P_i)″ (7)

Wherein, subscript i is measuring point number, and δ l are the spacing and measuring point i to the average of measuring point i+1 spacing of measuring point i-1 to measuring point i Value；

Final damage criterion takes the absolute value sum of the lower damage criterion of each across uniform load effect：

Wherein, IULSC is final damage criterion, and N is girder construction across number.

Uniform load P in step 3_iUsing unit force uniform load, i.e.,：

Wherein,For i-th is vectorial across the unit uniform load of loading, other are 0 vector.

Specifically, step 4 assumes that the moment of flexure of the front and rear each position of girder construction damage is identical, i.e.,

M_u(x)=M_d(x) (11)

Wherein, M_u(x)、M_dX () represents the moment of flexure that girder construction x position is damaged under front and rear uniform load effect respectively.

Specifically, step 5 by the mechanics of materials for by camber beam, being understood to meet before and after structural damage：

Wherein, EI (x) represents x position section rigidity, and ρ (x) represents x position sectional curvature radius.

It is assumed that the degree of injury of node is D_nX (), then have：

EI_d(x)=[1-D_n(x)]EI_u(x) (14)

Can be solved by formula (12)~(14) and obtain degree of injury：

Wherein：

Wherein w_ui″(x)、w_di" (x) is respectively uniform load P_iEffect lower beam structure damages the displacement curvature of front and rear x position, N is girder construction across number.

Damage moves forward and backward the relation of curvature：

The curvature being calculated by central difference method is nodal value, and reflection is Joint Damage degree, Joint Damage degree Relation with unit degree of injury is as shown in Figure 2, it is assumed that the degree of injury of temporary location is D_eThe damage of (x), both sides or so unit Hinder degree D_e(l)=D_eR ()=0, the then displacement curvature curve that actual cell damage causes such as " dotted line " in figure is shown, exist prominent Become, it is assumed that damage the moment magnification ratio for causing and cause to damage the nearby reduction of unit moment of flexure, i.e. M_d<M_u, therefore in 1,2 nodes (3,4 sections Point) between, the w ' being calculated by formula (18)_d′_eCompare w_u" small, unit is damaged between 2,3 nodes, causes displacement curvature to increase, 2nd, mutation is produced at 3 nodes, because numerical computations cannot consider the mutation, results of calculation is both integrated values, herein It is assumed that the average value of the two, i.e.,：

w″_de2l+w″_de2r=2w "_dn2 (19)

Wherein, w "_de2lRepresent No. 2 displacement curvature of the left unit of node of faulted condition, w "_de2rRepresent No. 2 nodes of faulted condition The displacement curvature of right unit, w "_dn2Represent No. 2 modal displacement curvature of faulted condition.

Formula (18) substitution above formula is obtained：

By D_el=0 substitution above formula abbreviation can obtain unit degree of injury and be with the relation of Joint Damage degree：

Wherein, D_eX () is x position unit degree of injury, D_nX () is x position Joint Damage degree.

The Joint Damage degree D that will be calculated by formula (15) in step 5_n(x)<0 value is set to 0.

Here is a concrete engineering example.It is a three-span continuous beam FEM model referring to Fig. 3, span setting is 10m+15m+10m, 1.0m divide a unit, altogether 35 units, 36 nodes, and (numeral in figure in upper row's circle is single Unit's numbering, lower row word is node serial number).Sectional dimension is b × h=300mm × 500mm, and elasticity modulus of materials is E=3.25 ×10⁴MPa, density is 2500kg/m³。

The reduction of the generation, material corrosion or elastic modelling quantity of the damage in engineering structure, such as crackle, can typically cause The rigidity of structure produces larger change, and the quality influence on structure is smaller.Therefore in FEM calculation, it is assumed that construction unit is damaged Wound only causes the decline of element stiffness, the change without causing element quality.The damage of unit by the reduction of elastic modelling quantity come Simulation, unless otherwise instructed, damage criterion erects curved modal calculation and obtains using first three rank in text.

Girder construction damage regime is as shown in table 1：

The damage regime of table 1

Specific implementation step is as follows：

Step 1：The modal parameter before and after three-span continuous beam is damaged is obtained respectively by FEM model simulation analysis, by preceding The vertical frequency of three ranks and the vibration shape calculate flexibility matrix F by formula (1) respectively_u、F_d。

Step 2：To three-span continuous beam respectively across uniform load is applied by cross, as shown in Fig. 4~Fig. 6, each uniform load effect Bottom offset curve as shown in fig. 7, displacement curve flex point correspondence moment of flexure be 0 position, as shown in Fig. 8~Figure 10, it is seen then that use When loading by cross, there was only two flex points, and the corner position difference under each load action under every kind of load situation, therefore use Uniform load loading, then carries out absolute value addition to its damage criterion by cross, will be prevented effectively from the influence of displacement curve flex point, The stationkeeping ability of damage criterion is improved, is multiplied each uniform load is poor with the flexibility matrix before and after structural damage, obtained accordingly Displacement difference, is calculated by formula (6).

Step 3：Take the i-th across uniform load P_iDisplacement difference curvature under effect is load P_iDamage criterion, based on formula (7) Calculate, final damage reason location index IULSC takes the absolute value sum of the lower damage criterion of each across uniform load effect, is calculated by formula (9). The index result of calculation of operating mode 1~3 is as shown in Figure 11~Figure 13, it is seen then that IULSC indexs are equal for single injury and poly-injury operating mode The correct identification of damage position of energy, as a comparison, the result of calculation of uniform load face curvature poor index ULSC is as shown in figure 14, only Damage position at span centre one can be recognized, wherein

Step 4：It is assumed that the Bending moment distribution that girder construction is damaged under front and rear uniform load effect does not change, i.e. M_u(x)=M_d (x)。

Step 5：According to formula (15) calculate node degree of injury D_n(x), by D_n(x)<0 value is set to 0, result of calculation difference As shown in Figure 15~Figure 18, it is seen then that the Joint Damage degree of IULSC indexs is respectively less than 1, and ULSC indexs node 14,23 is present Anomaly peak, it is impossible to correct recognition node degree of injury.Again by Joint Damage degree D_nX () substitutes into formula (21) and is calculated unit Degree of injury D_e, respectively as shown in Figure 19~Figure 21, it is seen then that do not consider the influence of moment of flexure change, the degree of injury of index identification It is general with the difference of actual damage degree within 0.05.

Step 6：The unit degree of injury D that step 5 is obtained_eIt is input in three-span continuous beam FEM model, calculates Bending moment distribution situation of change before and after being damaged to girder construction under uniform load effect, as shown in Figure 22~Figure 24, it is seen then that iteration one After secondary, moment of flexure changes close to theoretical value.Repeat step 5 obtains final unit degree of injury as shown in Figure 25~Figure 27, respectively The concrete numerical value of operating mode degree of injury is shown in Table 2, iteration once after, the desired value for only damaging unit is larger, and flash trimming unit 35 is damaged Degree error slightly increases outer, and other temporary location errors are obviously reduced, and damage extent identification result changes with by theoretical moment of flexure The result of calculating is approached, therefore moment of flexure changes before and after once considering structural damage with reference to FEM model iteration, you can more accurate Identify unit degree of injury.

The degree of injury result of calculation of table 2

Influence of the rank number of mode to damage criterion effect：

Above-mentioned analysis is using the result of three rank mode, in order to compare the pass of taken rank number of mode and flexibility matrix precision System, gives a definition following error criterion in Frobenius matrix norm meanings：

Wherein, F_tIt is flexibility matrix theoretical value, influences line to construct by each point in computation structure and obtain.

Obviously, the error criterion is the function of rank number of mode, to the three-span continuous beam in embodiment, rendering error index with The relation curve of taken rank number of mode is as shown in figure 28, it is seen then that preceding 3 rank mode lower curve declines quickly, and 3 rank time errors are 7.3%, curve is steady after 4 ranks, and error is reduced to 2.5%, and 7 ranks are reduced to 0.6%, illustrates that Modal Flexibility matrix is received under lower mode Hold back quickly, more accurate flexibility matrix can be constructed using 3 ranks and above mode, therefore can be damaged using first three rank mode Identification.

The foregoing is only one embodiment of the present of invention, all impartial changes done according to scope of the present invention patent with Modification, comes under covering scope of the invention.

Claims (10)

1. the girder construction damnification recognition method of a kind of face curvature of uniform load by cross difference, it is characterised in that comprise the following steps：

(1) obtain the modal parameter before and after girder construction is damaged respectively by test, flexibility matrix is calculated by frequency and the vibration shape respectively；

(2) it is each to girder construction across uniform load is applied by cross, uniform load is damaged into the front and rear poor phase of flexibility matrix with girder construction Multiply, obtain corresponding displacement difference；

(3) the i-th across uniform load P is taken_iDisplacement difference curvature under effect is load P_iDamage criterion, final damage reason location index Take the absolute value sum of the lower damage criterion of each across uniform load effect；

(4) assume that the Bending moment distribution that girder construction is damaged under front and rear uniform load effect does not change；

(5) moment of flexure change and displacement curvature estimation Joint Damage degree before and after being damaged according to girder construction, and then it is calculated list First degree of injury；

(6) if girder construction is redundant structure, the unit degree of injury that step (5) is obtained is input to girder construction FEM model In, the Bending moment distribution situation of change under uniform load effect before and after girder construction is damaged is calculated, repeat step (5) is obtained finally Unit degree of injury.

2. according to claim 1 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that：Step Suddenly (1) center sill structure damage before and after modal parameters test, respectively across measure-point amount be no less than 8, and damage before and after measuring point position Put arrangement identical.

3. according to claim 1 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that：Step Suddenly the rank number of mode that test is obtained in (1) is no less than 3 ranks.

4. according to claim 1 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that：Step Suddenly the method that modal parameters test use can survey excitation in (1), directly measures on the normalized vibration shape of mass matrix, or adopt Mass matrix is set up with the method for only measuring output and by the FEM model of girder construction, the vibration shape is normalized to mass matrix Afterwards, the Modal Flexibility matrix F represented using frequency and the vibration shape can be obtained：

$F={\mathrm{\&Phi;\&Omega;}}^{-1}{\mathrm{\&Phi;}}^T=\underset{i=1}{\overset{m}{\&Sigma;}}\frac{1}{{\mathrm{\&omega;}}_i^2}{\mathrm{\&phi;}}_i{\mathrm{\&phi;}}_i^T$

Wherein, Φ=[φ₁,φ₂,L,φ_m] it is vibration shape matrix, m is nominal modes, φ_i=[φ_i1 φ_i2 L φ_in]^TIt is i-th First order mode vector, n is measure-point amount,It is diagonal matrix, ω_iIt is the i-th rank circular frequency.

5. according to claim 4 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that：Step Suddenly the flexibility matrix difference before and after (2) center sill structure is damaged is Δ：

Δ=F_u-F_d

Wherein, F_uAnd F_dFront and rear flexibility matrix is respectively damaged, subscript " u ", " d " represent non-faulted condition and damage respectively in text Hinder state；

By the equation of static equilibrium of structure：

W=[w (1) w (2) L w (n)]^T=FP

Wherein, w is motion vector, and w (x) is the element value of the xth position in w, and P is load column vector；

For N across (N >=1) girder construction, by across N number of uniform load vector is taken, to any uniform load P therein_i, under its effect Girder construction damages front and rear displacement difference：

δw_i=w_ui-w_di=F_u·P_i-F_d·P_i=Δ P_i

Wherein, w_ui、w_diRespectively uniform load P_iEffect lower beam structure damages front and rear displacement.

6. according to claim 5 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that：Step Suddenly in (3), the i-th across uniform load P_iCorresponding damage criterion is：

ULSC_i=δ w "_i=(Δ P_i)″

${\mathrm{\&delta;w}}_i^{\&prime;\&prime;}=\frac{{\mathrm{\&delta;w}}_{i+1}-2{\mathrm{\&delta;w}}_i+{\mathrm{\&delta;w}}_{i-1}}{{\left(\mathrm{\&delta;}l\right)}^2}$

Wherein, subscript i is measuring point number, and δ l are the spacing of measuring point i-1 to measuring point i and the average value of measuring point i to measuring point i+1 spacing；

Final damage criterion takes the absolute value sum of the lower damage criterion of each across uniform load effect：

$IULSC=\underset{i=1}{\overset{N}{\&Sigma;}}\left|{\mathrm{ULSC}}_i\right|=\underset{i=1}{\overset{N}{\&Sigma;}}\left|{(\mathrm{\&Delta;}\&CenterDot;P_i)}^{\&prime;\&prime;}\right|$

Wherein, IULSC is final damage criterion, and N is girder construction across number.

7. according to claim 6 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that：Step Suddenly in (3), uniform load P_iUsing unit force uniform load, i.e.,：

$P_i={\left[\begin{array}{ccccccc}{p}_1^0& L& p_{i-1}^0& p_i^1& p_{i+1}^0& L& p_N^0\end{array}\right]}^T$

Wherein,For i-th is vectorial across the unit uniform load of loading, other are 0 vector.

8. according to claim 7 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that：Step Suddenly in (5), Joint Damage degree is calculated using equation below：

$D_n\left(x\right)=1-\frac{M_d\left(x\right)}{M_u\left(x\right)}\&CenterDot;\frac{w_u^{\&prime;\&prime;}\left(x\right)}{w_d^{\&prime;\&prime;}\left(x\right)}$

Wherein：

$w_u^{\&prime;\&prime;}\left(x\right)=\underset{i=1}{\overset{N}{\&Sigma;}}\left|{w_{ui}}^{\&prime;\&prime;}\left(x\right)\right|=\underset{i=1}{\overset{N}{\&Sigma;}}\left|{(F_u\&CenterDot;P_i)}^{\&prime;\&prime;}\left(x\right)\right|$

$w_d^{\&prime;\&prime;}\left(x\right)=\underset{i=1}{\overset{N}{\&Sigma;}}\left|{w_{di}}^{\&prime;\&prime;}\left(x\right)\right|=\underset{i=1}{\overset{N}{\&Sigma;}}\left|{(F_d\&CenterDot;P_i)}^{\&prime;\&prime;}\left(x\right)\right|$

Wherein, M_u(x)、M_dX () represents the moment of flexure that girder construction x position is damaged under front and rear uniform load effect, w respectively_ui″(x)、 w_di" (x) is respectively uniform load P_iEffect lower beam structure damages the displacement curvature of front and rear x position, and N is girder construction across number.

9. according to claim 8 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that：Step Suddenly value of the Joint Damage degree being calculated in (5) less than 0 is set to 0.

10. according to claim 9 by cross uniform load face curvature difference girder construction damnification recognition method, it is characterised in that： Unit degree of injury is calculated using equation below in step (5)：

$D_e\left(x\right)=\frac{2D_n\left(x\right)}{1+D_n\left(x\right)}$

Wherein, D_eX () is x position unit degree of injury, D_nX () is x position Joint Damage degree.