CN114218835A - Method for evaluating full-life anti-disaster performance of power transmission tower structure by considering wind-induced fatigue effect - Google Patents

Method for evaluating full-life anti-disaster performance of power transmission tower structure by considering wind-induced fatigue effect Download PDF

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CN114218835A
CN114218835A CN202111562201.7A CN202111562201A CN114218835A CN 114218835 A CN114218835 A CN 114218835A CN 202111562201 A CN202111562201 A CN 202111562201A CN 114218835 A CN114218835 A CN 114218835A
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潘海洋
李超
田利
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Dalian University of Technology
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Abstract

A power transmission tower structure full-life anti-multi-disaster performance evaluation method considering wind-induced fatigue effect is characterized by establishing a power transmission tower structure model, selecting and simulating seismic waves and coherent wind load time courses suitable for a structure; collecting actually measured wind speed and wind direction data of the structure, and calculating the occurrence probability and annual duration of different wind speeds and wind directions; simulating and generating wind load time courses of different wind speeds and wind directions according to the measured data, and loading the power transmission tower structure to obtain a structural stress response time course; counting stress circulation of the structural rod piece under the action of wind load, and calculating fatigue accumulated damage of the structural rod piece in unit time; updating material parameters of the structural rod pieces with different life cycles according to fatigue accumulated damage and a material fatigue performance time-varying model of the structural rod pieces, and establishing time-varying finite element models with different life stages considering wind-induced fatigue performance degradation; and evaluating the anti-disaster performance of the model in the whole life cycle, and verifying the influence of the wind-induced fatigue effect on the anti-disaster performance of the structure at different life stages.

Description

Method for evaluating full-life anti-disaster performance of power transmission tower structure by considering wind-induced fatigue effect
Technical Field
The invention belongs to the technical field of safety evaluation of power transmission tower structures in the civil engineering discipline, and particularly relates to a full-life anti-multiple-disaster performance evaluation method of a power transmission tower structure based on actual measurement data and with wind-induced fatigue effect taken into consideration.
Background
The power transmission tower structure is an important infrastructure of the country, takes charge of the task of power transmission and distribution, and greatly promotes the development of national economy. China is a country with frequent natural disasters such as earthquake and wind, so that the power transmission tower structure is inevitably attacked by various disasters such as earthquake and strong wind in the whole life cycle, and even is destructively damaged under the coupling action of the earthquake and the strong wind. The damage to the structure of the transmission tower not only affects the normal use of the structure, causing significant economic losses, but also severely affects the post-disaster rescue work and causes adverse social effects.
In a long service cycle of the power transmission tower structure, fatigue accumulation damage is easily caused by long-term wind load, so that the performance of a rod piece material is deteriorated, the integral performance of the structure is degraded, the disaster resistance of the structure is reduced, and serious potential safety hazards exist in the structure. Furthermore, as the intensity of disasters and the duration of wind-induced fatigue increase, the impact of wind-induced fatigue on the structure becomes more significant. Therefore, the wind-induced fatigue influence is considered in the structural full-life performance evaluation, and the method has great social significance and practical engineering significance.
At present, many scholars at home and abroad have studied on the performance evaluation of the transmission tower structure, but relatively few studies on the consideration of the wind-induced fatigue effect are carried out. In addition, in the existing structural wind-induced fatigue research, wind load lacks the support of measured data, and the influence of wind direction is rarely considered when the wind load is applied to the structure in the form of node force or a CFD (computational fluid dynamics) is utilized to simulate a flow field during the numerical calculation of structural response. Therefore, based on the analysis result of the actually measured wind speed and wind direction data, the fatigue damage of the structure is calculated by utilizing an S-N curve method, a rain flow counting method and a Palmgren-Mine linear criterion, and the anti-multiple-disaster performance of the structure at different service life stages is evaluated, so that the evaluation method of the full-service-life anti-multiple-disaster performance of the power transmission tower structure based on the actually measured data and considering the wind-induced fatigue effect is provided, and is of great importance to guarantee the safety and the functionality of the power transmission tower structure.
Disclosure of Invention
The invention aims to calculate the fatigue damage of a structure by utilizing the analysis result of actually measured wind speed and wind direction data and through an S-N curve method, a rain flow counting method and a Palmgren-Mine linear criterion, and provides a power transmission tower structure full-life anti-disaster performance evaluation method considering the wind-induced fatigue effect based on the actually measured data. The technical scheme is as follows: firstly, establishing a finite element analysis model of a power transmission tower structure, and selecting and simulating seismic waves and coherent wind load time courses suitable for a target structure; secondly, collecting actual measurement wind speed and direction data of a plurality of years in the area where the structure is located, calculating the probability of different wind speeds and directions and the annual duration time according to Gumbel, Frechet, Weibull and other probability distribution models, simulating and generating wind load time courses of different wind speeds and directions according to the analysis result of the actual measurement data, and loading the power transmission tower structure to obtain a corresponding structural stress response time course; secondly, counting stress cycles of the structural rod piece under the action of wind load by adopting a rain flow counting method, and calculating fatigue accumulated damage of the structural rod piece in unit time based on an S-N curve and a Palmgren-Mine linear criterion; then, according to fatigue accumulated damage of the structural rod piece and a material fatigue performance time-varying model, updating material parameters of the structural rod piece with different life cycles, and establishing time-varying finite element models with different life stages considering wind-induced fatigue performance degradation; and finally, carrying out the evaluation of the anti-disaster performance of the time-varying finite element models in different life stages in the whole life cycle, and verifying the influence of the wind-induced fatigue effect on the anti-disaster performance of the structure in different life stages.
A method for evaluating the full-life anti-disaster performance of a power transmission tower structure in consideration of wind-induced fatigue effect comprises the following steps:
the method comprises the following steps: establishing an initial finite element model and determining earthquake-strong wind input load
(1) Establishing a finite element analysis model of the power transmission tower structure according to an actual engineering drawing, and calculating modal information of the structure;
(2) selecting a certain number of natural seismic waves (generally 10-20 waves) according to the site information of the power transmission tower structure and the seismic fortification level; and simulating coherent wind load along the height direction of the structure by adopting a harmonic superposition method according to wind pressure data and site requirements of the area where the power transmission tower structure is located.
Step two: collecting and processing measured wind load data
(3) Collecting actual measurement wind load record data of the area for several years from a China meteorological office (CMA, http:// data, CMA. cn /) according to the geographical position of the power transmission tower structure, wherein the actual measurement wind load record data comprises the maximum wind speed and the corresponding wind direction;
(4) discretizing continuous wind direction data, and averagely dividing the continuous wind direction data into 16 wind direction angles theta between 0 DEG and 360 DEGK，θK(K-1) × 22.5 ° and θkIncreasing clockwise by a different thetaKThe values representing different wind directions, e.g. theta 10 ° denotes the north (N) wind direction, θ590 ° denotes the wind direction of the east (E), θ9180 ° denotes the south (S) wind direction, θ13270 ° denotes the true west (W) wind direction, θ15315 ° denotes north West (WN) wind direction;
(5) calculating the probability P (theta) of each wind direction occurring between statistical yearsK)，P(θK)＝nKN, where N represents the total number of wind load data collected during the statistical years, NKRepresenting the number of wind load data in the Kth wind direction;
(6) fitting the frequency distribution of the maximum wind speed in each wind direction by respectively adopting Gumbel, Frechet and Weibull probability distribution models, and determining a coefficient (R)2) Quantitatively comparing the fitting effect of each probability distribution model with a root mean square difference (RMSE), and selecting an optimized probability distribution model from the fitting effects;
(7) discretizing continuous wind speed data in each wind direction, dividing the whole wind speed range into M equidistant wind speed intervals, and selecting the median value of each interval as a representative wind speed
Figure BDA0003421001400000021
The value interval of the middle adjacent representative wind speed is Vmax/M, wherein VmaxRepresenting a maximum wind speed value over the entire wind speed range;
(8) according to the divided wind speed intervals and the fitted wind speed probability distribution, calculating the probability of each representative wind speed occurring in the corresponding wind direction
Figure BDA0003421001400000031
The expression is as follows:
Figure BDA0003421001400000032
in the formula (f)kIs the probability density function of the k wind download.
(9) Calculating the Kth wind direction theta within the statistical ageKThe ith one represents the wind speed ViProbability of occurrence
Figure BDA0003421001400000033
Step three: calculation of wind-induced fatigue damage
(10) And simulating different wind load time courses corresponding to the representative wind speed. Dividing the power transmission tower structure into r sections along the vertical direction and counting the height z of the central point of each section from the groundrAnd the central point of each section is the simulation point of the wind load. Calculating each representative wind speed in different wind directions
Figure BDA0003421001400000034
Average wind speed of lower simulation points
Figure BDA0003421001400000035
Figure BDA0003421001400000036
In the formula, eta is a surface roughness index, and the specific value can refer to building structure load specification; . Fast pulsating wind speed of each simulation point
Figure BDA0003421001400000037
The simulation is carried out by adopting a harmonic superposition method, and a Kaimal spectrum is adopted to represent a power normal density function of the fluctuating wind speed, wherein the expression is as follows:
Figure BDA0003421001400000038
in the formula (I), the compound is shown in the specification,
Figure BDA0003421001400000039
f is frequency, c is Monin coordinate, V*For the friction speed, k is von Karman constant. The cross-power spectrum between two points a and b in space can be represented as:
Figure BDA00034210014000000310
where coh (a, b; f) is a spatial coherence loss function, it can be calculated using the following empirical model:
Figure BDA00034210014000000311
where | a-b | represents the distance between points a and b in space,
Figure BDA00034210014000000312
the mean value of the average wind speed at two points a and b is shown, D is the attenuation coefficient, vappIs the apparent wave velocity. When a is<b, the spatial coherence function takes its complex conjugate. Calculating the wind loads at different heights of the structure as follows:
Figure BDA00034210014000000313
in the formula (I), the compound is shown in the specification,
Figure BDA00034210014000000314
denotes the structure at section r at thetaKFrontal area in the direction, CDIs the air resistance coefficient, rho is the air density;
(11) applying the simulated wind load time course to a finite element model of the power transmission tower structure according to the corresponding wind direction for power time course analysis, and extracting stress response time courses of all structural members of the structure;
(12) the stress response time course of the member can be decomposed into average wind
Figure BDA0003421001400000041
Induced mean stress
Figure BDA0003421001400000042
And by pulsating wind
Figure BDA0003421001400000043
Induced pulsating stress
Figure BDA0003421001400000044
Wherein the stress cycle caused by the pulsating wind is the root cause of fatigue damage. The average stress in the time-course distribution of the pulsating stress is counted by adopting a rain flow counting method
Figure BDA0003421001400000045
Number of stress cycles with stress amplitude Δ k
Figure BDA0003421001400000046
Obtaining the mean stress value of
Figure BDA0003421001400000047
Total number of fatigue failures caused by stress cycles with stress amplitude Δ k
Figure BDA0003421001400000048
Average wind speed ViThe wind direction being θKThe fatigue accumulated damage caused by the wind load with the duration t is as follows:
Figure BDA0003421001400000049
the fatigue accumulation damage caused by wind load in any time is as follows:
Figure BDA00034210014000000410
(13) considering all wind speed and wind direction distributions, the real fatigue damage of the structure at any time can be calculated according to the following formula:
Figure BDA00034210014000000411
step four: establishing a structural time-varying finite element model
(14) The reason that the structural performance is affected by fatigue during the service life is generally that the material performance of the rod member is affected by fatigue and is continuously degraded. Considering fatigue accumulation damage, the time-varying model of the material performance of the rod after degradation can be expressed as:
X(L)＝X×F[D(L)]
in the formula, X represents initial material properties such as elastic modulus, yield strength and the like of steel, and F is a degradation function.
(15) And replacing the initial material performance in the finite element model with a material performance time-varying model, and establishing the structural time-varying finite element model considering the wind-induced fatigue effect at different service life stages.
Step five: structural multi-disaster resistance performance assessment
(16) Performing a Pushover analysis on the structure to obtain a Pushover curve, and defining the damage state of the structure;
(17) randomly matching the earthquake motion selected in the step one and the simulated wind load by a Monte Carlo method to form N groups (usually more than 100) of earthquake-wind load pairs, and respectively carrying out power time-course analysis on different time-varying finite element models by adopting the generated load pairs to obtain corresponding structural response;
(18) calculating a multi-disaster vulnerability curved surface of a structure by adopting the following formula:
Figure BDA0003421001400000051
ln(SD)＝k1+k2ln IM1+k3ln IM2
Figure BDA0003421001400000052
in the formula, SDFor locations in the structural requirements, d is the threshold for the structural failure state, IM1And IM2Respectively representing seismic and wind load strength, DjFor the required value of the structure under the action of the jth 'earthquake-wind' load pair, k1，k2And k3Is a regression parameter;
Figure BDA0003421001400000053
and betaCRespectively, the logarithmic standard deviation of the structural requirements and capabilities.
(19) And substituting the calculated structural response into the formula to obtain the vulnerability curved surfaces of the structure at different service life stages considering the wind-induced fatigue effect, so that the full-service-life anti-disaster performance of the power transmission tower structure can be evaluated.
According to the whole process, the method for evaluating the full-life anti-multiple-disaster performance of the power transmission tower structure based on the measured data and considering the wind-induced fatigue effect can be obtained.
The invention has the beneficial effects that: the method overcomes the defect that the influence of wind-induced fatigue effect is neglected in the conventional evaluation process of the disaster resistance performance of the power transmission tower structure, and provides a corresponding calculation method for calculating the wind-induced fatigue cumulative damage by acquiring the actually measured wind speed and wind direction data of the area where the structure is located; calculating and realizing the influence of the wind-induced fatigue effect on the structural performance based on finite element analysis; the method for evaluating the performance of the structure under the coupling action of various disasters provides a technical scheme for evaluating the full-life anti-multiple-disaster performance of the power transmission tower structure considering the wind-induced fatigue effect.
Drawings
FIG. 1 is a basic flow diagram of the proposed method of the present invention;
fig. 2(a) is a model front view, fig. 2(b) is a model side view, and fig. 2(c) is a finite element diagram of a transmission tower structure according to an embodiment of the present invention;
fig. 3(a) and 3(b) are the measured maximum wind speed and the probability of each wind direction occurring in the Qingdao city for 50 years;
fig. 4 is an annual average fatigue damage value of the pole of the transmission tower according to the embodiment calculated based on measured data;
fig. 5 is a Pushover curve for defining different damage states of the transmission tower according to the embodiment;
fig. 6(a), fig. 6(b), fig. 6(c), fig. 6(d), fig. 6(e) and fig. 6(f) are respectively vulnerability curves of the transmission tower corresponding to a slight damage state at different life stages according to the embodiment;
fig. 7(a), fig. 7(b), fig. 7(c), fig. 7(d), fig. 7(e) and fig. 7(f) are the vulnerable curves of the transmission tower corresponding to the moderate damage state at different life stages according to the embodiment, respectively;
fig. 8(a), fig. 8(b), fig. 8(c), fig. 8(d), fig. 8(e) and fig. 8(f) are vulnerability curves of the transmission tower corresponding to a fully collapsed state at different life stages according to the embodiment, respectively.
Detailed Description
The specific implementation of the present invention is further described below with reference to the accompanying drawings and technical solutions, where a certain transmission tower structure in Qingdao city (as shown in fig. 2(a) and fig. 2 (b)) is selected as an example of the transmission tower structure of the present invention, and the transmission tower is a lattice steel pipe structure, and has a total height of 87.3m and a call height of 45 m; made of Q345 and Q420 steel pipes. The basic idea of the invention is shown in fig. 1, and a method for evaluating the full-life anti-disaster performance of a power transmission tower structure based on actual measurement data and considering a wind-induced fatigue effect is developed for the embodiment, and the specific implementation manner is as follows:
(1) and establishing a finite element model containing the structure of the embodiment, and calculating modal information. Selecting 20 natural earthquakes according to the seismic fortification intensity and the field category of the area where the power transmission tower is located; the seismic fortification intensity of the region is 8 degrees, and the seismic peak acceleration of the structural design is 0.2 g. According to the wind pressure data and the site requirements of the site where the power transmission tower is located, the coherent wind load in the height direction in the 50-year recurrence period is simulated, and the average wind speed is 30.89 m/s.
(2) CollectingWind load data of Qingdao city for 50 years (as shown in FIG. 3 (a)), and the probability P (theta) of each wind direction occurring between statistical years is calculatedK)，P(θK)＝nKand/N (as shown in FIG. 3 (b)). Fitting the frequency distribution of the maximum wind speed in each wind direction to obtain a corresponding wind load probability density function fk. The maximum value of the wind speed is 32m/s, therefore, the whole wind speed range is divided into 8 wind speed intervals with equal intervals, and 8 representative wind speeds are obtained
Figure BDA0003421001400000061
Calculating to obtain the Kth wind direction theta according to the probability of each wind direction and the corresponding wind load probability density functionKThe ith one represents the wind speed ViThe occurrence probability of (2):
Figure BDA0003421001400000062
and calculating the Kth wind direction theta within the statistical ageKThe ith one represents the wind speed ViProbability of occurrence:
Figure BDA0003421001400000063
(3) dividing the power transmission tower into 8 sections along the height direction and counting the height z of the central point of each section from the groundr. Calculating each representative wind speed in different wind directions
Figure BDA0003421001400000064
Average wind speed of lower simulation points
Figure BDA0003421001400000065
Figure BDA0003421001400000066
And a Kaimal spectrum is adopted to represent a power normal density function of the pulsating wind speed, and the expression is as follows:
Figure BDA0003421001400000067
the cross-power spectrum between two points a and b in space can be represented as:
Figure BDA0003421001400000071
wherein the spatial coherence loss function coh (a, b; f) can be expressed as:
Figure BDA0003421001400000072
calculating the wind loads at different heights of the structure as follows:
Figure BDA0003421001400000073
(4) and applying the simulated wind load time course to a finite element model of the power transmission tower for power time course analysis, and extracting stress response time courses of all structural members of the structure. Based on a rain flow counting method and an S-N curve, calculating the average wind speed as ViThe wind direction being θKFatigue accumulation damage caused by wind load with duration t:
Figure BDA0003421001400000074
the fatigue accumulation damage caused by wind load in any time is as follows:
Figure BDA0003421001400000075
and (3) calculating the average fatigue damage of the power transmission tower at any time by considering all wind speed and wind direction distributions:
Figure BDA0003421001400000076
taking T as 1 year, the annual average fatigue damage value of the transmission tower bar can be obtained (as shown in fig. 4).
(5) Considering fatigue accumulated damage, calculating the performance of the time-varying material of the rod piece by adopting a linear degradation model:
fy(T)(or fu(T))＝fy(or fu)·[1-D(T)]
ES(T)＝ES·[1-ζD(T)]
wherein f isy(T),fu(T)and ES(T) is the time-varying yield strength, ultimate strength, and elastic modulus, respectively. And replacing the initial material performance in the finite element model with a material performance time-varying model, and establishing the structural time-varying finite element model considering the wind-induced fatigue effect at different service life stages.
(6) Pushover analysis is carried out on the power transmission tower to obtain a Pushover curve (as shown in a figure (5)). Three damage states of the transmission tower are defined: mild injury, moderate injury, and complete collapse. And (3) defining a required value corresponding to the buckling point as a threshold value of a fully collapsed state by combining a Pushover curve, and selecting 50% and 75% of the threshold value of the fully collapsed state as threshold values of slight damage and moderate damage.
(7) And C, randomly matching the earthquake motion selected in the step one and the simulated wind load by a Monte Carlo method to form 120 groups of earthquake-wind load pairs, and performing dynamic time-course analysis on different time-varying finite element models by adopting the generated load pairs to obtain corresponding structural response. Respectively selecting the seismic oscillation peak acceleration PGA and the average wind speed at the elevation position of 10m above the ground
Figure BDA0003421001400000081
The method is used as an intensity index of earthquake and wind load, and the calculated structural response is fitted in a logarithmic space to obtain a multi-disaster demand model:
ln(SD)＝k1+k2ln IM1+k3ln IM2
according to the obtained multi-disaster demand model, calculating multi-disaster vulnerability curved surfaces of the power transmission tower at different service life stages:
Figure BDA0003421001400000082
fig. 6(a) - (f), fig. 7(a) - (f) and fig. 8(a) - (f) show the multi-disaster vulnerability surfaces of the transmission tower corresponding to the states of slight damage, moderate damage and complete collapse at different life stages, respectively. Under the combined action of 0.2g design earthquake and 30.98m/s wind load in 50-year recurrence period, the probability of slight damage of the transmission tower in 0 year and 50 years is 32.59 percent and 77.16 percent respectively; the probabilities of overtaking moderate lesions were 7.93% and 47.71%, respectively; the probability of exceeding complete collapse is 1.73% and 25.95%, respectively. Along with the increase of service time, the probability that the power transmission tower exceeds the same damage state under the given earthquake motion-wind load strength is continuously increased; the accumulation of fatigue damage is constantly degrading the performance of the transmission tower.
As can be seen from the comparative analysis, the method provided by the invention can calculate the fatigue damage of the power transmission tower structure at different service time according to the actually measured wind data, and can also evaluate the anti-disaster performance of the power transmission tower structure at different service life stages. The invention can provide an important technical means for the safety design of the power transmission tower structure.

Claims (1)

1. A method for evaluating the full-life anti-disaster performance of a power transmission tower structure in consideration of wind-induced fatigue effect is characterized by comprising the following steps:
the method comprises the following steps: establishing an initial finite element model and determining earthquake-strong wind input load
(1) Establishing a finite element analysis model of the power transmission tower structure according to an actual engineering drawing, and calculating modal information of the power transmission tower structure;
(2) selecting 10-20 natural seismic waves according to the site information of the power transmission tower structure and the seismic fortification level; simulating coherent wind load along the height direction of the power transmission tower structure by adopting a harmonic superposition method according to wind pressure data and site requirements of the area where the power transmission tower structure is located;
step two: collecting and processing measured wind load data
(3) Collecting actually measured wind load record data of the area according to the geographical position of the power transmission tower structure, wherein the actually measured wind load record data comprise the maximum wind speed and the corresponding wind direction;
(4) discretizing continuous wind direction data, and averagely dividing the continuous wind direction data into 16 wind direction angles theta between 0 DEG and 360 DEGK，θK(K-1) × 22.5 ° and θkIncreasing clockwise by a different thetaKValues represent different wind directions; theta10 ° represents the north wind direction, θ590 ° indicates the wind direction in the east, θ9180 deg. for positive south wind direction, theta13270 ° denotes true west wind direction, θ15315 ° represents the northwest wind direction;
(5) calculating the probability P (theta) of each wind direction occurring between statistical yearsK)，P(θK)＝nKN, where N represents the total number of wind load data collected during the statistical years, NKRepresenting the number of wind load data in the Kth wind direction;
(6) fitting the frequency distribution of the maximum wind speed in each wind direction by using Gumbel, Frechet and Weibull probability distribution models respectively, quantitatively comparing the fitting effect of each probability distribution model according to a decision coefficient and a root-mean-square difference, and selecting an optimized probability distribution model from the fitting effects;
(7) discretizing continuous wind speed data in each wind direction, dividing the whole wind speed range into M equidistant wind speed intervals, and selecting the median value of each interval as a representative wind speed
Figure FDA0003421001390000014
The value interval of the middle adjacent representative wind speed is Vmax/M, wherein VmaxRepresenting a maximum wind speed value over the entire wind speed range;
(8) according to the divided wind speed intervals and the fitted wind speed probability distribution, calculating the probability of each representative wind speed occurring in the corresponding wind direction
Figure FDA0003421001390000011
The expression is as follows:
Figure FDA0003421001390000012
in the formula (f)kIs the probability density function of the kth downwind load;
(9) calculating the Kth wind direction theta within the statistical ageKThe ith one represents the wind speed ViProbability of occurrence:
Figure FDA0003421001390000013
step three: calculation of wind-induced fatigue damage
(10) Simulating wind load time courses corresponding to different representative wind speeds; dividing the power transmission tower structure into r sections along the vertical direction and counting the height z of the central point of each section from the groundrThe central point of each section is the simulation point of the wind load; calculating each representative wind speed in different wind directions
Figure FDA0003421001390000021
Average wind speed of lower simulation points
Figure FDA0003421001390000022
Figure FDA0003421001390000023
In the formula, eta is a surface roughness index, and the value is referred to building structure load specification; fast pulsating wind speed of each simulation point
Figure FDA0003421001390000024
The simulation is carried out by adopting a harmonic superposition method, and a Kaimal spectrum is adopted to represent a power normal density function of the fluctuating wind speed, wherein the expression is as follows:
Figure FDA0003421001390000025
in the formula (I), the compound is shown in the specification,
Figure FDA0003421001390000026
f is frequency, c is Monin coordinate, V*K is von Karman constant as friction speed; the cross-power spectrum between two points a and b in space is represented as:
Figure FDA0003421001390000027
in the formula, coh (a, b; f) is a spatial coherence loss function and is calculated by adopting the following empirical model:
Figure FDA0003421001390000028
where | a-b | represents the distance between points a and b in space,
Figure FDA0003421001390000029
the mean value of the average wind speed at two points a and b is shown, D is the attenuation coefficient, vappThe apparent wave velocity; when a is less than b, the space coherent function takes the conjugate complex number of the space coherent function; calculating the wind loads at different heights of the structure as follows:
Figure FDA00034210013900000210
in the formula (I), the compound is shown in the specification,
Figure FDA00034210013900000211
representing the section r of the power transmission tower structure at thetaKFrontal area in the direction, CDIs the air resistance coefficient, rho is the air density;
(11) applying the simulated wind load time course to a finite element model of the power transmission tower structure according to the corresponding wind direction for power time course analysis, and extracting stress response time courses of all structural members of the structure;
(12) the stress response time course of the member is decomposed into average wind
Figure FDA00034210013900000212
Induced mean stress
Figure FDA00034210013900000213
And by pulsating wind
Figure FDA00034210013900000214
Induced pulsating stress
Figure FDA00034210013900000215
Wherein the stress cycle caused by pulsating wind is the root cause of fatigue damage; the average stress in the time-course distribution of the pulsating stress is counted by adopting a rain flow counting method
Figure FDA00034210013900000216
Number of stress cycles with stress amplitude Δ k
Figure FDA00034210013900000217
Obtaining the mean stress value of
Figure FDA00034210013900000218
Total number of fatigue failures caused by stress cycles with stress amplitude Δ k
Figure FDA00034210013900000219
Average wind speed ViThe wind direction being θKThe fatigue accumulated damage caused by the wind load with the duration t is as follows:
Figure FDA0003421001390000031
the fatigue accumulation damage caused by wind load in any time is as follows:
Figure FDA0003421001390000032
(13) considering all wind speed and wind direction distributions, the real fatigue damage of the structure at any time can be calculated according to the following formula:
Figure FDA0003421001390000033
step four: establishing a structural time-varying finite element model
(14) Considering fatigue accumulation damage, the time-varying model of the material performance of the rod after degradation is expressed as follows:
X(L)＝X×F[D(L)]
wherein X represents the initial material property and F is a degradation function;
(15) establishing a structural time-varying finite element model considering wind-induced fatigue effect at different life stages by replacing the initial material performance in the finite element model with a material performance time-varying model;
step five: structural multi-disaster resistance performance assessment
(16) Performing a Pushover analysis on the structure to obtain a Pushover curve, and defining the damage state of the structure;
(17) randomly matching the earthquake motion selected in the step one and the simulated wind load by a Monte Carlo method to form N groups of earthquake-wind load pairs, and respectively carrying out power time-course analysis on different time-varying finite element models by adopting the generated load pairs to obtain corresponding structural response;
(18) calculating a multi-disaster vulnerability curved surface of a structure by adopting the following formula:
Figure FDA0003421001390000034
ln(SD)＝k1+k2ln IM1+k3ln IM2
Figure FDA0003421001390000035
in the formula, SDFor locations in the structural requirements, d is the threshold for the structural failure state, IM1And IM2Respectively representing seismic and wind load strength, DjFor the required value of the structure under the action of the jth 'earthquake-wind' load pair, k1，k2And k3Is a regression parameter;
Figure FDA0003421001390000036
and betaCRespectively representing the logarithmic standard deviation of the structural requirements and capabilities;
(19) substituting the calculated structural response into the formula to obtain vulnerability curved surfaces of the structure at different service life stages considering the wind-induced fatigue effect, thereby carrying out the evaluation of the full-service-life anti-disaster performance of the power transmission tower structure;
according to the whole process, the method for evaluating the full-life anti-multiple-disaster performance of the power transmission tower structure based on the measured data and considering the wind-induced fatigue effect can be obtained.
CN202111562201.7A 2021-12-20 2021-12-20 Method for evaluating full-life anti-disaster performance of power transmission tower structure by considering wind-induced fatigue effect Pending CN114218835A (en)

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