CN102043019A - Method for identifying damages of frame structure - Google Patents

Abstract

The invention discloses a method for identifying damages of a frame structure. The method comprises the following steps: firstly, testing an undamaged frame structure, and carrying out model modification on an initial discretization model of the frame structure so as to obtain an accurate finite element theoretical model, and calculating a structural modal parameter (omega A0, phi A0); then, testing the damaged frame structure, and carrying out model analysis on the damaged frame structure so as to obtain a modal parameter (omega t2, phi t2); and finally, establishing a direct analysis method damage identification equation, and solving an unit damage coefficient Di (i=1, 2,..., n) by using front n (n is less than or equal to N) order frequencies and vibration mode variation value delta omega r (r=1, 2,..., n) of the frame structure before and after damage so as to achieve the purpose of simultaneously identifying the number, position and size of the damages existing in the whole structure. The method is suitable for the damage identification of a construction frame structure, and has the advantages of less required detection data amount, high efficiency and higher precision.

Description

A kind of frame structure damage recognition methods

Technical field

The invention belongs to the building frame construction detection technique, be specifically related to a kind of damnification recognition method of building frame construction.

Background technology:

With regard to As-Is, in China's field of civil engineering,, caused great casualties and property loss because artificial or natural factors cause accident constantly to take place, this has caused extensive concern and the great attention of people to the Important Project security.With regard to historical situation, China has been used decades even gone up century-old historical building, wherein be no lack of a lot of near in addition surpass the building of design reference period, frequent natural calamity in recent years, also historical building has been caused damage in various degree, how about are their security and reliability so? this also more and more causes people's close attention.Therefore, the structural behaviour of existing building is monitored and diagnosed, find the damage of structure timely, the disaster that may occur is predicted, assess its security, become inevitable requirement.

Structural damage detection is an existing basic theory as a kind of troubleshooting issue, and the integrated technology of actual engineering background is arranged again.The detection method of structural damage from detecting the scope angle of being implemented, can be divided into local detection and whole detection.

The local damage detection is to use Dynamic Non-Destruction Measurement to concentrate the special key member of inside configuration is detected, and is applied in civil engineering work comparatively maturely at present.Existing main detection method has supercritical ultrasonics technology, acoustic-emission, infra-red method, shock wave method, radar method and microwave method etc.The local damage detection method also only limits on the structural elements level, is difficult to reflect integrally-built performance degradation comprehensively, can't realize on-line monitoring and damage.

The whole detection technology can be discontinuously or is measured the health status of structure continuously, also can instruct the damage check of Suspected Area, improves detection efficiency.Ultimate principle based on the vibration damage recognition technology is: the damage of structure will inevitably cause the variation of structural dynamic feature.Many scholars have proposed many methods in view of the above, and the application of achieving success in practice, but still limit to some extent on the degree of the quantity of recognition structure damage, position and size at the same time.

Document " the direct analytical method of Damage Assessment Method (Tongji University's journal, 2007,35 (6): 719～723) " has been introduced the analytical method this method of a kind of method of damaging identification-directly.Promptly from structural modal finite element formula, the function of frequency and the vibration shape being regarded as impairment parameter, obtain frequency, the vibration shape single order partial derivative through Taylor expansion to impairment parameter, construct then with the impairment parameter be the overdetermination line of unknown quantity for system of equations, find the solution and obtain whole impairment parameter values.Quantity, position and the degree of structural damage can be identified simultaneously, and the impairment parameter of any most amounts can be discerned.

The mode truncated error is big, the slow problem of iteration convergence but said method exists, thereby it is many to detect the desired data amount, and recognition efficiency and precision are lower.

Summary of the invention

Purpose of the present invention is exactly in order to overcome the deficiency of said method, a kind of frame structure damage recognition methods to be provided, and it is few that this method detects desired data amount, and the efficient height has higher precision.

Frame structure damage recognition methods provided by the invention, its step comprises:

(1) at the every layer of installation acceleration transducer that damages the front baffle structure, preceding 8 order frequencies and vibration shape data are extracted in the time-histories of test structure response under the incentive action outside, and framed structure discretize initial model is carried out the model correction, obtain accurate finite element theory model, computation structure modal parameter (ω _A0, Φ _A0);

(2) the every layer of installation acceleration transducer of structure after the damage tested, the time-histories of test structure response and carry out model analysis under the incentive action outside obtains modal parameter (ω _T2, Φ _T2);

(3) one order of trying to achieve natural frequency is:

$\frac{\&PartialD;{\mathrm{\&omega;}}_r}{\&PartialD;D_i}=\frac{1}{2{\mathrm{\&omega;}}_r}({{\mathrm{\&Phi;}}_r}^T\frac{\&PartialD;K_d}{\&PartialD;D_i}{\mathrm{\&Phi;}}_r-{{\mathrm{\&Phi;}}_r}^T{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HSA00000310938500011.png,HSA00000310938500032.png"\; state="\{\{state\}\}">r</figure-callout>}}^2\frac{\&PartialD;M}{\&PartialD;D_i}{\mathrm{\&Phi;}}_r)$

(4) the mode truncated error is improved in finding the solution the Mode Shape process adopted the algorithm after improving; The vibration shape to the single order partial derivative of Damage coefficient is:

$\frac{\&PartialD;{\mathrm{\&Phi;}}_r}{\&PartialD;D_i}=\underset{s=1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{\&alpha;}}_s{\mathrm{\&Phi;}}_s$ Wherein: ${\mathrm{\&alpha;}}_s=\left\{\begin{array}{cc}-\frac{1}{2}{\mathrm{\&Phi;}}_r^T\frac{\&PartialD;M}{\&PartialD;D_i}{\mathrm{\&Phi;}}_r& s=r\\ \underset{s=1}{\overset{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HSA00000310938500011.png,HSA00000310938500032.png"\; state="\{\{state\}\}">N</figure-callout>}}{\mathrm{\&Sigma;}}}\frac{2{\mathrm{\&omega;}}_s^2-{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HSA00000310938500011.png,HSA00000310938500032.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}{{\mathrm{\&omega;}}_s^2({\mathrm{\&omega;}}_s^2-{\mathrm{\&omega;}}_r^2)}{{\mathrm{\&Phi;}}_s}^T({\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HSA00000310938500011.png,HSA00000310938500032.png"\; state="\{\{state\}\}">r</figure-callout>}}^2\frac{\&PartialD;M}{\&PartialD;D_i}-\frac{\&PartialD;K_d}{\&PartialD;D_i}){\mathrm{\&Phi;}}_r& s\&NotEqual;r\end{array}\right.$

(5) set up direct analytical method damage identification equations [S] D}={ Δ f}, wherein: { Δ f} is frequency and vibration shape difference array, and { D} is the array that unit impairment parameter to be asked constitutes, and [S] is frequency and the vibration shape matrix to unit impairment parameter single order partial derivative formation;

(6) { D}={ Δ f} disposablely obtains whole impairment parameter values to find the solution overdetermined equation group [S].{ D} determines the degree of damage, by checking the numbering of damage member, obtains damage position to utilize parameter value; Like this, reach the purpose of quantity, position and the size of the damage of discerning the total existence simultaneously.

Frame structure damage recognition methods of the present invention is in order to improve accuracy of identification and engineering practicality, on the basis of document " the direct analytical method of Damage Assessment Method (Tongji University's journal; 2007; 35 (6): 719～723) ", mainly carried out the improvement of two aspects, aspect mode ending error, reduced and discerned required mode number; Reduce iterations aspect the equation iterative solution method, improving recognition efficiency and accuracy of identification.

Description of drawings:

Fig. 1 is five layer of two plane frame structure synoptic diagram of striding of example of the present invention;

Fig. 2 is 6 iteration recognition results that general mode truncated error method is selected preceding 23 rank mode;

Fig. 3 is 2 iteration recognition results that general mode truncated error method is selected preceding 16 rank mode;

Fig. 4 selects 14 iteration recognition results of preceding 16 rank mode for improving mode truncated error method;

Fig. 5 is 6 iteration recognition results selecting preceding 16 rank mode after the improvement equations system method;

Fig. 6 distributes for the value of approaching of each equations system method correspondence;

Fig. 7 is general direct analytical method recognition result;

Fig. 8 is improved direct analytical method recognition result;

Fig. 9 realizes synoptic diagram for frame structure damage method of identification computer program of the present invention;

Figure 10 is subroutine 1 process flow diagram;

Figure 11 is subroutine 2 process flow diagrams.

Embodiment:

The improvement of two aspects has mainly been carried out in frame structure damage recognition methods of the present invention, aspect the mode truncated error, has reduced and has discerned required mode number; Reduce iterations aspect the equation iterative solution method, improving recognition efficiency and accuracy of identification

1) to the improvement of mode truncated error

1. the vibration shape to the single order partial derivative of Damage coefficient is before improving

(h＝1，2，…，N)

Wherein,

2. the vibration shape to the single order partial derivative of Damage coefficient is after improving:

(h＝1，2，…，N)

Wherein,

2) to the improvement of equations system method

Constraint least square algorithm iteration characteristics and minimum least square method search rapidly optimizing function is combined, a kind of mixing iterative method has been proposed, specific practice is as follows: iteration is found the solution (because its solving precision height can reduce the scope of separating greatly) with Constraint least square algorithm for the first time; All the other iterative process adopt minimum least square method to find the solution (because its search capability is strong, can progressively converge to exact solution).This not only makes convergence of algorithm speed obviously increase, and accuracy of identification is also than higher.

Embodiment:

Fig. 1 is five layer of two plane frame structure synoptic diagram of striding of example of the present invention, and numeral is an element number in the circle, and all the other are node serial number.Five layer of two reinforced concrete plane frame structure of striding, each floor floor height is 4m, total height of structure 20m, frame column net spacing is 6m, the sectional dimension of Vierendeel girder is 0.3m * 0.5m, and the sectional dimension of center pillar is 0.5m * 0.5m, and the sectional dimension of side column is 0.5m * 0.6m.The density of institute's materials used is 2500kg/m ³, elastic modulus is 3 * 10 ¹⁰N/m ²The damage of structure shows as element stiffness and reduces, and quality remains unchanged.Fig. 9 realizes synoptic diagram for frame structure damage method of identification computer program of the present invention; Figure 10 is subroutine 1 process flow diagram; Figure 11 is subroutine 2 process flow diagrams.

1) separately to the improved front and back contrast of mode ending error

To adopt self-editing direct analytical method damage recognizer below, at five layer of two plane frame structure of striding of a Pin, damage is set to the right beam of one deck, and (unit number is 17, see Fig. 1), degree of injury is 30%, adopts the direct analytical method of improved and not improved mode truncated error respectively, and equations system method all adopts minimum least square method (being the generalized inverse method) to find the solution the damage fundamental equation, this damage is discerned the recognition effect before and after relatively improving.

The recognition methods of general mode truncated error needs iteration 6 times, and the minimum rank number of mode that needs is 23, and iterative process the results are shown in Figure 2.The recognition methods of the mode truncated error after the improvement, iteration 13 times, the minimum rank number of mode that needs is 16, iterative process the results are shown in Figure for 4 (horizontal ordinate is represented unit number, and ordinate is represented lesion size).In order to contrast recognition effect, select preceding 16 rank modal parameters with not improved method, found that: because the mode truncated error seriously causes producing complex mode, iteration can't go on, and iterative process the results are shown in Figure 3.

By Fig. 2, Fig. 3 and Fig. 4 as can be known: the mode truncated error can obtain correct recognition result before and after improving, and different is that improved method makes the mode number reduce by 7, and this uses engineering is very helpful.Speed of convergence after improving in addition descends to some extent, but this can improve its speed by improving equations system method.

2) separately to equations system method improved front and back contrast

On essence, directly the solution procedure of analytical method is a process that model progressively approaches, in order to describe the approximation ratio of its iteration, adopt the iteration mode and the 2-norm of the difference of damage mode to describe, be designated as A (, being referred to as the value of approaching), the value of the approaching A of j step iteration for ease of describing _jCalculating formula is

A _jNumerical value big more, illustrate that approximation ratio is poor more; Otherwise approximation ratio is good more.Should be increase in theory along with iterations, A _jIt is zero that value reduces until at last gradually.Calculate 13 iterative approach values of separate equation solution respectively, as shown in Figure 6.

By Fig. 5 and Fig. 6 as can be known: the speed of convergence of improving one's methods approximately is 2 times of conventional method, and iterations has reduced by 8, has reduced 9.72 seconds computing time.As can be seen: improved method combines the strong and high advantage of Constraint least square algorithm solving precision of search capability of conventional method fully.This example shows that improved equations system method is effectively, compares with general method, restrains sooner, and solving precision is also than higher.

3) adopt above-mentioned two kinds of improved front and back contrasts simultaneously

As can be seen from the above analysis, for single injury, improved method has good identification effect, and the situation of poly-injury once is discussed below.Damage is provided with sees Fig. 1, and the damage operating mode sees Table 1.Adopt respectively and general it damaged identification with improved method, identification the results are shown in Figure 7 and Fig. 8.

The supposition of table 1 damage operating mode

Annotate: G1, G2, G3 represent respectively to damage operating mode.

By Fig. 7 and Fig. 8 as can be known: the general direct analytical method before improving needs the mode number many, wherein can't discern damage with one deck beam, and the mode number that the back method of the present invention of improvement is not only discerned needs is fewer, and computing time and iterations are also fewer, also can identify the damage with one deck beam in addition, the improvement of two aspects of being undertaken by conventional method is effective as can be seen.

Claims (1)

1. frame structure damage recognition methods, its step comprises:

(1) at the every layer of installation acceleration transducer that damages the front baffle structure, preceding 8 order frequencies and vibration shape data are extracted in the time-histories of test structure response under the incentive action outside, and framed structure discretize initial model is carried out the model correction, obtain accurate finite element theory model, computation structure modal parameter (ω _A0, Φ _A0);

(2) the every layer of installation acceleration transducer of structure after the damage tested, the time-histories of test structure response and carry out model analysis under the incentive action outside obtains modal parameter (ω _T2, Φ _T2);

(3) one order of trying to achieve natural frequency is:

$\frac{\&PartialD;{\mathrm{\&omega;}}_r}{\&PartialD;D_i}=\frac{1}{2{\mathrm{\&omega;}}_r}({{\mathrm{\&Phi;}}_r}^T\frac{\&PartialD;K_d}{\&PartialD;D_i}{\mathrm{\&Phi;}}_r-{{\mathrm{\&Phi;}}_r}^T{\mathrm{\&omega;}}_r^2\frac{\&PartialD;M}{\&PartialD;D_i}{\mathrm{\&Phi;}}_r);$

(4) trying to achieve the vibration shape to the single order partial derivative of Damage coefficient is:

$\frac{\&PartialD;{\mathrm{\&Phi;}}_r}{\&PartialD;D_i}=\underset{s=1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{\&alpha;}}_s{\mathrm{\&Phi;}}_s$ Wherein: ${\mathrm{\&alpha;}}_s=\left\{\begin{array}{cc}-\frac{1}{2}{\mathrm{\&Phi;}}_r^T\frac{\&PartialD;M}{\&PartialD;D_i}{\mathrm{\&Phi;}}_r& s=r\\ \underset{s=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{2{\mathrm{\&omega;}}_s^2-{\mathrm{\&omega;}}_r^2}{{\mathrm{\&omega;}}_s^2({\mathrm{\&omega;}}_s^2-{\mathrm{\&omega;}}_r^2)}{{\mathrm{\&Phi;}}_s}^T({\mathrm{\&omega;}}_r^2\frac{\&PartialD;M}{\&PartialD;D_i}-\frac{\&PartialD;K_d}{\&PartialD;D_i}){\mathrm{\&Phi;}}_r& s\&NotEqual;r\end{array}\right.$

(5) set up direct analytical method damage identification equations [S] D}={ Δ f}, wherein: { Δ f} is frequency and vibration shape difference array, and { D} is the array that unit impairment parameter to be asked constitutes, and [S] is frequency and the vibration shape matrix to unit impairment parameter single order partial derivative formation;

(6) find the solution overdetermined equation group [S] { D}={ Δ f}, disposablely obtain whole impairment parameter values, { D} determines the degree of damage to utilize parameter value, by checking the numbering of damage member, obtain damage position, like this, reach the purpose of quantity, position and the size of the damage of discerning the total existence simultaneously.

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