CN105069190A - Tower material strength evaluation and calculation method for providing criterion for evaluation of tower structure - Google Patents

Abstract

The invention discloses a tower material strength evaluation and calculation method for providing a criterion for evaluation of a tower structure. The method comprises the following steps of applying a rough set theory to carry out reduction on an index set; adopting a method of combining subjective weight and objective weight to determine an evaluation index weight; and applying a fuzzy mathematical method to comprehensively evaluate and calculate the actual strength of a tower material according to the established evaluation grade set in order to solve a typical uncertain problem of unclear validity of a factor that affects the tower material strength in an evolutionary process. The method can provide an important science criterion for security evaluation of the tower structure.

Description

For iron tower structure assessment provides tower material strength assessment and the computing method of criterion

The application is application number: the divisional application of 201410423096.2, the applying date: 2014.8.26, title " a kind of transmission tower tower material strength assessment based on Rough Fuzzy Sets and computing method ".

Technical field

The present invention relates to the evaluation of transmission tower structural strength and calculate field, be specially adapted to the transmission tower safety appraisement of structure of long-time running under Complex Natural Environment.

Background technology

The essence of line construction safety is the evolutionary process of a uncertain state space, shape State evolution (transfer) process has randomness, the characteristic information wherein characterizing shaft tower tower material actual machine intensity has inexactness, the effect validity of influence factor is also unintelligible, definition and the extension of running status have ambiguity, the expertise of state-evaluation has incompleteness, so be a complicated uncertain problem to the evaluation of circuit tower material intensity with calculating.

Fuzzy overall evaluation is based on fuzzy mathematics, its basic thought utilizes fuzzy transfer principle, by degree of membership theory, qualitative evaluation is converted into quantitative evaluation, consider each correlative factor, comprehensive evaluation is carried out, successively upwards, until the highest destination layer from each factor of lowermost level level, thus relatively objective, correct, a realistic evaluation is made to the things or object being subject to many factors restriction, and then solve the practical problems with ambiguity.It has the advantages that result is clear, systematicness is strong, can solve fuzzy, to be difficult to quantification problem preferably, be applicable to the solution of multiple uncertain problems.

Fuzzy overall evaluation is applied on shaft tower tower material strength assessment also exists some shortcomings: first, the factor affecting tower material intensity is a lot, and traditional fuzzy overall evaluation needs to calculate whole evaluation index, so calculate more complicated, and may the serious distortion phenomenon that cause because each factor weight is little or multi-peak phenomenon; Secondly, for the determination that index weights is determined, because the judgment criteria etc. of each expert has difference, net result also can be variant, so subjective.The present invention is based on rough set theory and carry out yojan to index set, after yojan, binding hierarchy analytic approach and FUZZY SET APPROACH TO ENVIRONMENTAL carry out comprehensive evaluation, avoid some shortcomings that traditional fuzzy overall evaluation exists.Institute's extracting method effectively solves the transmission tower safety appraisement of structure problem of long-time running under Complex Natural Environment.

Summary of the invention

The object of the invention is to: propose a kind of transmission tower tower material strength assessment based on Rough Fuzzy Sets and computing method, can directly for the safety evaluation of assessment iron tower of power transmission line provides necessary criterion.

An actual strength appraisal procedure for long-time running transmission tower tower material, is characterized in that: comprise the steps:

Step 1: index set yojan;

Step 2: set of factors weight is determined;

Step 3: subordinate function is determined;

Step 4: actual strength is assessed.

Index set yojan in described step 1, mainly to the index set by meteorologic district condition, sub-strength damage, the stress of conductor and mechanical vibration three major types factors composition, three class influence factor set representations are U={U ₁, U ₂, U ₃.Wherein: U ₁={ u ₁₁, u ₁₂, u ₁₃, u ₁₄, u ₁₅, u ₁₁for wind speed (most strong wind), u ₁₂for atmospheric temperature (lowest temperature), u ₁₃for average temperature of the whole year, u ₁₄for ice covering thickness (the thickest icing), u ₁₅for number of days in thunderstorm day in year.U ₂={ u ₂₁, u ₂₂, u ₂₃, u ₂₄, u ₂₅, u ₂₆, u ₂₁for working time, u ₂₂for bending reparation number of times, u ₂₃for slight crack repairs number of times, u ₂₄for thunder and lightning or fault current damage number of times, u ₂₅to attach most importance to icing times of fatigue, u ₂₆for on average running stress/maximum operation stress.U ₃={ u ₃₁, u ₃₂, u ₃₃, u ₃₄, u ₃₁for wire division number, u ₃₂for wind direction and circuit angle, u ₃₃for ground surface degree of roughness, u ₃₄for steel corrosion amount.Use rough set to carry out index set yojan, Attribute Significance is defined as:

U/R＝{{1,7},{2,4},{3,6,8},{5}}

U/(R-{u ₁₁})＝{{1,3,5,7,8},{2,4}}

U/(R-{u ₁₂})＝{{1,2,4,5,7},{3,6,8}}

U/(R-{u ₁₃})＝{{1,7},{2,4},{3,6,8},{5}}

U/(R-{u ₁₄})＝{{1,5,7},{2,4},{3,6,8}}

U/(R-{u ₁₅})＝{{1,7},{2,4},{3,6,8},{5}}

U/(R-{u ₁₃,u ₁₅})＝{{1,7},{2,4},{3,6,8},{5}}

U/R≠U/(R-{u ₁₁})

U/R≠U/(R-{u ₁₂})

U/R≠U/(R-{u ₁₄})

U/R＝U/(R-{u ₁₃})＝U/(R-{u ₁₅})＝U/(R-{u ₁₃,u ₁₅})

Calculate through Attribute Significance yojan, u ₁₃, u ₁₅index is redundancy, and in like manner, carry out Attribute Significance yojan to sub-strength damage factor and the stress of conductor and mechanical vibration factor respectively, obtaining final evaluation index is: U={U ₁, U ₂, U ₃, wherein U ₁={ u ₁₁, u ₁₂, u ₁₄, U ₂={ u ₂₁, u ₂₂, u ₂₃, u ₂₄, u ₂₅, U ₃={ u ₃₁, u ₃₂, u ₃₃, u ₃₄;

The index weights of the set of factors in described step 2 is determined, adopt the method that subjective weight and objective weight combine, determine evaluation criterion weight, make strength assessment result more scientific in conjunction with subjectivity and objectivity impact, RS weight and the MAHP weight optimization combinational algorithm of the actual strength assessment of the shaft tower tower material that the present invention proposes are as follows:

w＝μw ₁+(1-μ)w ₂

Wherein, μ (0< μ <1) is weight factor, the significance level of RS weight and MAHP weight in reflected appraisal process.W is the weighted value under RS and MAHP combination, w ₁for the weighted value under RS, w ₂for the weighted value under MAHP.

1) rough set model is set up:

An infosystem S can be expressed as a four-tuple S={U _s, R _s, V _s, f _s.Wherein, U _suniverse (set that object is formed, U _s={ x ₁, x ₂..., x _m); R _sit is property set; V _sit is the set of property value; f _sfrom U _s× R _sto V _sinformation function.If community set u _s/ IND (B)={ x ₁x ₂x _m, then the quantity of information of B is defined as:

$I\left(B\right)=\underset{i=1}{\overset{m}{\&Sigma;}}\frac{\left|X_i\right|}{\left|U_1\right|}\&lsqb;1-\frac{\left|X_i\right|}{\left|U_1\right|}\&rsqb;=1-\frac{1}{{\left|U_1\right|}^2}\underset{i=1}{\overset{m}{\&Sigma;}}{\left|X_i\right|}^2$

Wherein, | X _i| represent equivalence class set X _iradix.

Removing { b in B _ithe size definition of caused afterwards quantity of information change is { b _iattribute Significance, { b _iimportance degree can be expressed as:

${\mathrm{SIG}}_{B-\left\{b_i\right\}}\left(b_i\right)=I\left(B\right)-I(B-\{b_i\left\}\right)$

Attribute { b _iweight definition be:

$w_{b_i}=\frac{{\mathrm{SIG}}_{B-\left\{b_i\right\}}\left(b_i\right)}{\underset{j=1}{\overset{m}{\&Sigma;}}{\mathrm{SGF}}_{B-\left\{b_j\right\}}\left(b_j\right)}=\frac{I\left(B\right)-I\left(B-\left\{b_i\right\}\right)}{mI\left(B\right)-\underset{j=1}{\overset{m}{\&Sigma;}}I\left(B-\left\{b_j\right\}\right)}$

2) MAHP weight is determined:

(1) hierarchical structure is set up by above formula;

(2) Judgement Matricies;

Judgment matrix P defining method: p _i, p _j(i, j=1,2 ..., n) represent same level evaluation index, two indices compared, p _ijrepresent p _ito p _jrelative importance numerical value;

(3) the eigenvalue of maximum λ of judgment matrix P is obtained _maxand characteristic of correspondence vector W, W normalization is the weight w of this level factor, calculates eigenvalue of maximum λ by judgment matrix P _max=3.0053 and individual features vector W=(0.4185,0.5500,0.7228), the weight that normalization obtains each factor is w=(0.2474,0.3252,0.4274);

(4) consistency desired result.The step of consistency desired result is as follows:

A) coincident indicator CI is calculated, $CI=\frac{{\mathrm{\&lambda;}}_{max}-n}{n-1}=\frac{3.0053-3}{3-1}=0.00265;$

B) foundation n=3 tables look-up and obtains Aver-age Random Consistency Index RI=0.58;

C) consistency ration is calculated (if during CR<0.10, think that the consistance of judgment matrix is acceptable, otherwise reply judgment matrix doing suitable correction):

(5) weight that above-mentioned steps obtains each first class index and two-level index is repeated.

Membership function in described step 3 can obtain the influence degree of certain factor to shaft tower tower material actual strength, and by probabilistic factor sharpening, the membership function of the actual strength assessment of the shaft tower tower material that the present invention proposes adopts Gauss model as follows:

$r_{ij}=\left\{\begin{array}{cc}1& x\&le;d_{i1},x\&GreaterEqual;d_{in}\\ \exp \left(-\frac{{\left(x-d_{i\left(j-1\right)}\right)}^2}{2{\left(d_{ij}-d_{i\left(j-1\right)}\right)}^2}\right)& d_{i\left(j-1\right)}<x<d_{ij}\\ \exp \left(-\frac{{\left(d_{ij}-x\right)}^2}{2{\left(d_{i\left(j+1\right)}-d_{ij}\right)}^2}\right)& d_{ij}<x<d_{i\left(j+1\right)}\\ 0& x\&le;d_{i\left(j-1\right)},x\&GreaterEqual;d_{i\left(j+1\right)}\end{array}\right.$

In formula: r _ijrepresent that i-th kind of factor is to the degree of membership of jth level opinion rating; x _irepresent i-th kind of actual occurrence value of factor; d _ijrepresent the standard value of i-th kind of factor in jth level evaluation criterion; I=1,2 ..., m; J=2,3 ..., n-1.

Actual strength assessment in described step 4, according to the opinion rating collection set up, uses the tower material actual strength value that fuzzy overall evaluation calculates, and the fuzzy synthetic appraisement method of the actual strength of the shaft tower tower material that the present invention proposes is as follows:

A) one-level fuzzy overall evaluation:

Factor U is obtained by membership function _ievaluation fuzzy relation R _i, r _{kj (i)}represent at factor U _imiddle secondary kth kind factor is to the degree of membership of jth level evaluation criterion, and carry out one-level fuzzy overall evaluation to each factor, evaluation result is designated as B _i, that is:

Wherein: b _i1=a _i1r _{11 (i)}+ a _i2r _{21 (i)}+ ... + a _imr _{m1 (i)}.

Again by B _inormalization obtains B' _i, note B' _i=[b' _i1b' _i2b' _in], wherein:

B) Secondary Fuzzy Comprehensive Evaluation:

On the basis of one-level fuzzy overall evaluation, by evaluation vector B' _isynthesize R, wherein R is that set of factors U is to evaluating the fuzzy relation matrix collecting Y, i.e. comprehensive evaluation transformation matrix.Carry out Secondary Fuzzy Comprehensive Evaluation, be designated as B, that is:

Wherein: b _i=A ₁r _1i+ A ₂r _2i+ ... + A _mr _mi.

Again B normalization is obtained final fuzzy evaluation vector B', B' and remember B'=[b' ₁b' ₂b' _n], wherein: $b_i^{\&prime;}=b_i/\underset{j=1}{\overset{n}{\&Sigma;}}{b}_j,(i=1,2,...,n).$

Technique effect of the present invention:

The application is compared to classic method, index is not only made to be simplified, and make the weight allocation of each factor comparatively reasonable, the discrimination of its evaluation result is obvious, result gears to actual circumstances more, its method adopting subjective weight and objective weight to combine, the reflected appraisal result making evaluation index more effective.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of the actual strength computing method of long-time running power transmission line column material.

Fig. 2 is actual strength result of calculation figure.

Fig. 3 is intensity evaluation result figure.

Embodiment

As shown in Figure 1, the method mainly comprises the steps: the actual strength computing method of a kind of long-time running power transmission line column material of the present invention

(1) basic index Establishing:

By in power supply enterprise's investigation, according to the evaluation index affecting the various factors of tower material intensity that person skilled provides, in conjunction with a large amount of real data, draw 110kV electric pressure line steel tower intensity evaluation basic index system.Basic index system is primarily of meteorologic district condition, sub-strength damage, the stress of conductor and mechanical vibration three major types factors composition.

Set of factors is: U={U ₁, U ₂, U ₃, wherein U ₁={ u ₁₁, u ₁₂, u ₁₃, u ₁₄, u ₁₅, U ₂={ u ₂₁, u ₂₂, u ₂₃, u ₂₄, u ₂₅, u ₂₆, U ₃={ u ₃₁, u ₃₂, u ₃₃, u ₃₄.

1) meteorologic district condition U ₁:

Wind speed (most strong wind) u ₁₁, atmospheric temperature (lowest temperature) u ₁₂, average temperature of the whole year u ₁₃, ice covering thickness (the thickest icing) u ₁₄, thunderstorm day in year number of days u ₁₅.

2) sub-strength damage U ₂:

Working time u ₂₁, bending reparation number of times u ₂₂, slight crack repairs number of times u ₂₃, thunder and lightning or fault current damage number of times u ₂₄, re-cover ice times of fatigue u ₂₅, on average run stress/maximum operation stress u ₂₆.

3) stress of conductor and mechanical vibration U ₃:

Wire division number u ₃₁, wind direction and circuit angle u ₃₂, ground surface degree of roughness u ₃₃, steel corrosion amount is u ₃₄.

Because the value of each factor is different, and comparatively complicated, in order to the convenience that further evaluation calculates, at this, data normalization is carried out to basic index.Five grades are divided into according to the influence degree difference of factor of evaluation to tower material intensity, be respectively I, II, III, IV, V, grade I represents very little on the impact of tower material actual strength, grade II represents less on the impact of tower material actual strength, grade III represents medium on the impact of tower material actual strength, grade IV represents comparatively large on the impact of tower material actual strength, and grade V represents very large on the impact of tower material actual strength.Set up meteorologic district for meteorologic district below and evaluate quantitative criteria.

Set up the evaluation criterion of meteorologic district condition by national typical meteorological condition area storehouse, show that quantitative criteria is evaluated in meteorologic district, in table 1.

Quantitative criteria is evaluated in table 1 meteorologic district

(2) rough set carries out attribute reduction:

The many factors of basic index system, may the problem of existing factor redundancy, on the basis of not effect appraise result, in order to not allow evaluation procedure complicated, will carry out yojan to basic index system.Test sample data are as shown in table 2, and for the ease of computational short cut, the desired value using II is as the threshold values of each initial evaluation index, the desired value meeting II is then 1, otherwise is 0, then carry out Data Discretization by table 2 and table 3 data, just initial evaluation indication information can be drawn, in table 3.

Table 2 test sample data

Table 3 sample data discretize

According to rough set theory, his-and-hers watches 4 carry out Attribute Significance yojan:

U/R＝{{1,7},{2,4},{3,6,8},{5}}

U/(R-{u ₁₁})＝{{1,3,5,7,8},{2,4}}

U/(R-{u ₁₂})＝{{1,2,4,5,7},{3,6,8}}

U/(R-{u ₁₃})＝{{1,7},{2,4},{3,6,8},{5}}

U/(R-{u ₁₄})＝{{1,5,7},{2,4},{3,6,8}}

U/(R-{u ₁₅})＝{{1,7},{2,4},{3,6,8},{5}}

U/(R-{u ₁₃,u ₁₅})＝{{1,7},{2,4},{3,6,8},{5}}

U/R≠U/(R-{u ₁₁})

U/R≠U/(R-{u ₁₂})

U/R≠U/(R-{u ₁₄})

U/R＝U/(R-{u ₁₃})＝U/(R-{u ₁₅})＝U/(R-{u ₁₃,u ₁₅})

Through Attribute Significance yojan, calculate known index u ₁₃, u ₁₅it is redundancy.In like manner, carry out Attribute Significance yojan to sub-strength damage factor and the stress of conductor and mechanical vibration factor respectively, obtaining final evaluation index is: U={U ₁, U ₂, U ₃, wherein U ₁={ u ₁₁, u ₁₂, u ₁₄, U ₂={ u ₂₁, u ₂₂, u ₂₃, u ₂₄, u ₂₅, U ₃={ u ₃₁, u ₃₂, u ₃₃, u ₃₄.

(3) weight is determined:

In fuzzy overall evaluation, the whether reasonable of weight has vital effect to evaluation result.At present, the method that weight is determined mainly contains can subjective weighting method and objective weighted model.The former rule of thumb carries out judgement primarily of expert and draws weight, so it is random to have stronger subjectivity, and objectivity is poor; The latter mainly determines weight according to the relation between raw data, does not rely on the subjective judgement of people, but the impact calculated by sample changed is larger.The advantage of comprehensive two kinds of methods herein, adopts Evaluation formula, and the mode that namely weight adopts rough set method and improved AHP method to combine is determined, makes evaluation result more close to actual.

1) rough set method:

An infosystem S can be expressed as a four-tuple S={U _s, R _s, V _s, f _s.Wherein, U _suniverse (set that object is formed, U _s={ x ₁, x ₂..., x _m); R _sit is property set; V _sit is the set of property value; f _sfrom U _s× R _sto V _sinformation function.If community set u _s/ IND (B)={ x ₁x ₂x _m, then the quantity of information of B is defined as:

$I\left(B\right)=\underset{i=1}{\overset{m}{\&Sigma;}}\frac{\left|X_i\right|}{\left|U_1\right|}\&lsqb;1-\frac{\left|X_i\right|}{\left|U_1\right|}\&rsqb;=1-\frac{1}{|U_1{|}^2}\underset{i=1}{\overset{m}{\&Sigma;}}|X_i{|}^2$

Wherein, | X _i| represent equivalence class set X _iradix.

Removing { b in B _ithe size definition of caused afterwards quantity of information change is { b _iattribute Significance, { b _iimportance degree can be expressed as:

${\mathrm{SIG}}_{B-\left\{b_i\right\}}\left(b_i\right)=I\left(B\right)-I(B-\{b_i\left\}\right)$

Attribute { b _iweight definition be:

$w_{b_i}=\frac{{\mathrm{SIG}}_{B-\left\{b_i\right\}}\left(b_i\right)}{\underset{j=1}{\overset{m}{\&Sigma;}}{\mathrm{SGF}}_{B-\left\{b_j\right\}}\left(b_j\right)}=\frac{I\left(B\right)-I(B-\{b_i\left\}\right)}{mI\left(B\right)-\underset{j=1}{\overset{m}{\&Sigma;}}I(B-\{b_j\left\}\right)}$

Attribute Significance yojan is carried out to index set above, then according to formula, just tried to achieve the weight of I and II index respectively, in table 5.

2) improved AHP method of the present invention:

1. set up hierarchical structure.Assessment indicator system and opinion rating are set up all.

2. Judgement Matricies.Judgement Matricies is the process quantized by the multilevel iudge of people, therefore affects very large by the subjective factor of people, and the determination of the judgment matrix basis that to be weight determine, so a very important step in Judgement Matricies formula analytical hierarchy process.Traditional analytical hierarchy process adopts 1-9 scale, because it exists limitation, result may be caused not conform to the actual conditions,

Therefore the present invention proposes improvement to analytical hierarchy process, propose new Scale Method, the subjectivity greatly reduced in traditional weights deterministic process is random.

Judgment matrix P defining method: p _i, p _j(i, j=1,2 ..., n) represent same level evaluation index, two indices compared, p _ijrepresent p _ito p _jrelative importance numerical value, p _ijvalue rule in table 4.

Table 4p _ijvalue rule

For the two-level index of meteorologic district, set up judgment matrix $P=\left[\begin{array}{ccc}\frac{10}{10}& \frac{9}{11}& \frac{7}{13}\\ \frac{11}{9}& \frac{10}{10}& \frac{9}{11}\\ \frac{13}{7}& \frac{11}{9}& \frac{10}{10}\end{array}\right].$

3. obtain the eigenvalue of maximum λ of judgment matrix P _maxand characteristic of correspondence vector W, W normalization is the weight w of this level factor, calculates eigenvalue of maximum λ by judgment matrix P _max=3.0053 and individual features vector W=(0.4185,0.5500,0.7228), the weight that normalization obtains each factor is w=(0.2474,0.3252,0.4274);

4. consistency desired result.The step of consistency desired result is as follows:

5. first calculate coincident indicator CI, $CI=\frac{{\mathrm{\&lambda;}}_{max}-n}{n-1}=\frac{3.0053-3}{3-1}=0.00265;$

A) then foundation n=3 tables look-up and obtains Aver-age Random Consistency Index RI=0.58;

B) finally consistency ration is calculated (if during CR<0.10, think that the consistance of judgment matrix is acceptable, otherwise reply judgment matrix doing suitable correction).

6. repeat the weight that above-mentioned steps obtains each first class index and two-level index, in table 5.

The general computing formula providing weight and weight optimization combination is as follows:

w＝μw ₁+(1-μ)w ₂

Wherein, μ (0< μ <1) is weight factor, the significance level of RS weight and MAHP weight in reflected appraisal process, and w is the weighted value under RS and MAHP combination, w ₁for the weighted value under RS, w ₂for the weighted value under MAHP.According to different regions different situations, can be determined voluntarily by estimator.Get 0.5 herein, each index weights is in table 5.

The weight of table 5 index

(4) determination opinion rating collection of the present invention:

Opinion rating collection uses Y={y usually ₁, y ₂..., y _nrepresent, wherein y _i(i=1,2 ..., n kind different brackets n) expressed possibility.N=5 herein, namely consider and be divided into (very well, well, medium, poor, very poor) 5 grades, every grade of respective value is { 95%, 85%, 75%, 65%, 55%}.

(5) subordinate function is determined:

In the evaluates calculation of tower material intensity, membership function is most important to evaluation result.The influence degree of certain factor to tower material intensity can be obtained, by probabilistic factor sharpening by subordinate function.By the analysis and research to tower material feature in operation, consider the relation between this kind of each standard value of factor in the actual occurrence value of certain factor and quantification of targets standard simultaneously, adopt the method for Gaussian function, take out the membership function model in general tower material intensity evaluation, membership function adopts Gauss model as follows:

$r_{ij}=\left\{\begin{array}{cc}1& x\&le;d_{i1},x\&GreaterEqual;d_{in}\\ \exp (-\frac{{(x-d_{i(j-1)})}^2}{2{(d_{ij}-d_{i(j-1)})}^2})& d_{i(j-1)}<x<d_{ij}\\ \exp (-\frac{{(d_{ij}-x)}^2}{2{(d_{i(j+1)}-d_{ij})}^2})& d_{ij}<x<d_{i(j+1)}\\ 0& x\&le;d_{i(j-1)},x\&GreaterEqual;d_{i(j+1)}\end{array}\right.$

In formula: r _ijrepresent that i-th kind of factor is to the degree of membership of jth level evaluation criterion;

X _irepresent i-th kind of actual occurrence value of factor;

D _ijrepresent the standard value of i-th kind of factor in jth level evaluation criterion;

Wherein i=1,2 ..., m; J=2,3 ..., n-1.

(6) fuzzy overall evaluation:

1) one-level fuzzy overall evaluation of the present invention:

Factor U is obtained by membership function _ievaluation fuzzy relation R _i, r _{kj (i)}represent at factor U _imiddle secondary kth kind factor is to the degree of membership of jth level evaluation criterion.Carry out one-level fuzzy overall evaluation to each factor, evaluation result is designated as B _i, that is:

Wherein b _i1=a _i1r _{11 (i)}+ a _i2r _{21 (i)}+ ... + a _imr _{m1 (i)}.

Again by B _inormalization obtains B' _i, note B' _i=[b' _i1b' _i2b' _in], wherein

2) Secondary Fuzzy Comprehensive Evaluation of the present invention:

On the basis of one-level fuzzy overall evaluation, by evaluation vector B' _isynthesize R, wherein R is that set of factors U is to evaluating the fuzzy relation matrix collecting Y, i.e. comprehensive evaluation transformation matrix.Carry out Secondary Fuzzy Comprehensive Evaluation, be designated as B, that is:

Wherein b _i=A ₁r _1i+ A ₂r _2i+ ... + A _mr _mi.

Again B normalization is obtained final fuzzy evaluation vector B', B' and remember B'=[b' ₁b' ₂b' _n], wherein $b_i^{\&prime;}=b_i/\underset{j=1}{\overset{n}{\&Sigma;}}{b}_j,(i=1,2,...,n).$

Adopt maximum membership grade principle to draw opinion rating, its corresponding value is α.Table look-up and draw the desirable pull-off force T of tower material _p, the comprehensive breaking strength usually getting tower material is 95% of desirable pull-off force, i.e. 95%T _p.Therefore the comprehensive breaking strength T' of tower material intensity _p=α 95%T _p.

Be T by calculating end points pulling force under complex working condition _t, by T _twith T' _pcompare, draw the net result of iron tower structure safety.If T _t> T' _p, then represent in the case can steel tower dangerous.

Embodiment:

For the strain resistant steel tower of certain Utilities Electric Co., transfer the detailed weather data of nearly 5 years, and the detailed service data that steel tower puts into operation, through native system again inverse modeling, system security level is Failure risk state.In addition, for some other major defect situation, be fractured into example with actual column material, components of system as directed (<10%) gives the Failure risk state of broken string, and system security level shows slightly conservative.The result of its circuit intensity and evaluation as Figure 2-3.

The above is only preferred embodiment of the present invention, is not restriction the present invention being made to any other form, and any amendment done according to technical spirit of the present invention or equivalent variations, still belong to the present invention's scope required for protection.

Claims (1)

1., for iron tower structure assessment provides tower material strength assessment and computing method for criterion, it is characterized in that: comprise the steps:

Step 1: index set yojan;

Step 2: set of factors weight is determined;

Step 3: subordinate function is determined;

Step 4: actual strength is assessed;

The concrete grammar of described step 2:

Adopt Evaluation formula, the mode that namely weight adopts rough set method and improved AHP method to combine is determined, makes evaluation result more close to actual;

1) rough set method:

An infosystem S can be expressed as a four-tuple S={U _s, R _s, V _s, f _s; Wherein, U _suniverse (set that object is formed, U _s={ x ₁, x ₂..., x _m); R _sit is property set; V _sit is the set of property value; f _sfrom U _s× R _sto V _sinformation function; If community set u _s/ IND (B)={ x ₁x ₂x _m, then the quantity of information of B is defined as:

$I\left(B\right)=\underset{i=1}{\overset{m}{\&Sigma;}}\frac{\left|X_i\right|}{\left|U_1\right|}\&lsqb;1-\frac{\left|X_i\right|}{\left|U_1\right|}\&rsqb;=1-\frac{1}{|U_1{|}^2}\underset{i=1}{\overset{m}{\&Sigma;}}|X_i{|}^2$

Wherein, | X _i| represent equivalence class set X _iradix;

Removing { b in B _ithe size definition of caused afterwards quantity of information change is { b _iattribute Significance, { b _iimportance degree can be expressed as:

${\mathrm{SIG}}_{B-\left\{b_i\right\}}\left(b_i\right)=I\left(B\right)-I(B-\{b_i\left\}\right)$

Attribute { b _iweight definition be:

$w_{b_i}=\frac{{\mathrm{SIG}}_{B-\left\{b_i\right\}}\left(b_i\right)}{\underset{j=1}{\overset{m}{\&Sigma;}}{\mathrm{SGF}}_{B-\left\{b_j\right\}}\left(b_j\right)}=\frac{I\left(B\right)-I\left(B-\left\{b_i\right\}\right)}{mI\left(B\right)-\underset{j=1}{\overset{m}{\&Sigma;}}I\left(B-\left\{b_j\right\}\right)}$

Attribute Significance yojan is carried out to index set above, then according to formula, just tried to achieve the weight of I and II index respectively;

2) improved AHP method of the present invention:

A. hierarchical structure is set up: assessment indicator system and opinion rating are set up all;

B. Judgement Matricies:

Judgment matrix P defining method: p _i, p _j(i, j=1,2 ..., n) represent same level evaluation index, two indices compared, p _ijrepresent p _ito p _jrelative importance numerical value, p _ijvalue rule:

For the two-level index of meteorologic district, set up judgment matrix $P=\left[\begin{array}{ccc}\frac{10}{10}& \frac{9}{11}& \frac{7}{13}\\ \frac{11}{9}& \frac{10}{10}& \frac{9}{11}\\ \frac{13}{7}& \frac{11}{9}& \frac{10}{10}\end{array}\right];$

C. the eigenvalue of maximum λ of judgment matrix P is obtained _maxand characteristic of correspondence vector W, W normalization is the weight w of this level factor, calculates eigenvalue of maximum λ by judgment matrix P _max=3.0053 and individual features vector W=(0.4185,0.5500,0.7228), the weight that normalization obtains each factor is w=(0.2474,0.3252,0.4274);

D. consistency desired result; The step of consistency desired result is as follows:

E. first coincident indicator CI is calculated, $CI=\frac{{\mathrm{\&lambda;}}_{max}-n}{n-1}=\frac{3.0053-3}{3-1}=0.00265;$

A) then foundation n=3 tables look-up and obtains Aver-age Random Consistency Index RI=0.58;

B) finally consistency ration is calculated if during CR<0.10, think that the consistance of judgment matrix is acceptable, otherwise reply judgment matrix does suitable correction;

F. the weight that above-mentioned steps obtains each first class index and two-level index is repeated;

The general computing formula providing weight and weight optimization combination is as follows:

w＝μw ₁+(1-μ)w ₂

Wherein, μ (0< μ <1) is weight factor, the significance level of RS weight and MAHP weight in reflected appraisal process, and w is the weighted value under RS and MAHP combination, w ₁for the weighted value under RS, w ₂for the weighted value under MAHP;

The weight of index