基于輸電塔風(fēng)毀模式的結(jié)構(gòu)優(yōu)化設(shè)計(jì)研究
本文選題:輸電塔 + 優(yōu)化設(shè)計(jì) ; 參考:《武漢大學(xué)》2014年博士論文
【摘要】:對(duì)大量輸電塔在強(qiáng)風(fēng)作用下的倒塔事故進(jìn)行統(tǒng)計(jì)分析可知,目前多種類型輸電塔的結(jié)構(gòu)設(shè)計(jì)從抗風(fēng)性能的角度來看不盡合理。輸電塔結(jié)構(gòu)在強(qiáng)風(fēng)作用下存在典型的易損構(gòu)件、薄弱部位和風(fēng)毀模式。因此,如何在盡可能少地增加結(jié)構(gòu)材料的基礎(chǔ)上大大提高塔結(jié)構(gòu)的抗風(fēng)性能就成為極有研究?jī)r(jià)值的課題,也就是說,輸電塔抗風(fēng)優(yōu)化設(shè)計(jì)研究是具有重要的工程意義、長(zhǎng)遠(yuǎn)的社會(huì)效應(yīng)和廣闊的應(yīng)用前景的研究課題。 風(fēng)致響應(yīng)的計(jì)算是輸電塔優(yōu)化設(shè)計(jì)的前提。目前,輸電塔線體系風(fēng)荷載理論模型尚未建立,風(fēng)洞試驗(yàn)也僅能得到代表性測(cè)點(diǎn)的風(fēng)致響應(yīng),風(fēng)荷載反演中又存在風(fēng)荷載形式假定與實(shí)際不符的問題。目前,輸電塔的優(yōu)化大多數(shù)是基于構(gòu)件層次的,從整體角度優(yōu)化時(shí)又未能考慮工程中的不確定性。 針對(duì)目前輸電塔抗風(fēng)優(yōu)化設(shè)計(jì)中存在的不足,在前人基礎(chǔ)上,本文在等效風(fēng)荷載計(jì)算和風(fēng)毀模式分析的基礎(chǔ)上同時(shí)考慮工程中多因素的不確定性對(duì)輸電塔的優(yōu)化設(shè)計(jì)進(jìn)行研究。具體地說,本文的研究工作主要包括以下幾個(gè)方面: (1)從風(fēng)洞試驗(yàn)的測(cè)點(diǎn)位移響應(yīng)擬合得到各個(gè)構(gòu)件的風(fēng)致響應(yīng)。首先,由單塔的風(fēng)洞試驗(yàn)得到的測(cè)點(diǎn)位移響應(yīng)平均值擬合得到輸電塔體型系數(shù),由塔線體系的風(fēng)洞試驗(yàn)得到的測(cè)點(diǎn)位移響應(yīng)平均值與對(duì)應(yīng)風(fēng)速下單塔風(fēng)洞試驗(yàn)測(cè)點(diǎn)的位移響應(yīng)平均值的差得到線的體型系數(shù)。然后,由塔線體系風(fēng)洞試驗(yàn)得到的順風(fēng)向測(cè)點(diǎn)位移響應(yīng)時(shí)程得到各順風(fēng)向測(cè)點(diǎn)位移響應(yīng)的方差、協(xié)方差,擬合順風(fēng)向以塔為主的第一模態(tài)的廣義位移方差,由塔線體系風(fēng)洞試驗(yàn)得到的橫風(fēng)向測(cè)點(diǎn)位移響應(yīng)時(shí)程得到各橫風(fēng)向測(cè)點(diǎn)位移響應(yīng)的方差、協(xié)方差,擬合橫風(fēng)向以塔為主的第一模態(tài)的廣義位移方差。最后,把平均風(fēng)荷載加到有限元模型上得到各個(gè)構(gòu)件的平均響應(yīng),把順風(fēng)向第一模態(tài)對(duì)應(yīng)的響應(yīng)與橫風(fēng)向第一模態(tài)對(duì)應(yīng)的響應(yīng)進(jìn)行組合得到構(gòu)件響應(yīng)的均方根,把平均響應(yīng)疊加峰值倍均方根即得到各個(gè)構(gòu)件的風(fēng)致響應(yīng)。 (2)進(jìn)行了輸電塔在強(qiáng)風(fēng)作用下的失效模式及對(duì)策研究。首先,按上述方法得到風(fēng)致響應(yīng),與自重響應(yīng)一起考慮進(jìn)行輸電塔失效模式識(shí)別,得到主要失效模式及其極限風(fēng)速,計(jì)算結(jié)果與實(shí)際倒塔案例相比較。然后,發(fā)展了兩種提高輸電塔抗風(fēng)承載力的對(duì)策。第一種對(duì)策是對(duì)輸電塔風(fēng)致破壞的薄弱部位進(jìn)行加固,提高其抗風(fēng)承載力,文中輸電塔進(jìn)行了3次加固。第二種對(duì)策是通過優(yōu)化關(guān)鍵桿件的設(shè)計(jì)參數(shù)來提高其抗風(fēng)承載力。通過編制程序,.實(shí)現(xiàn)了某輸電塔若干風(fēng)速的自動(dòng)優(yōu)化。 (3)提出了基于極限承載力的輸電塔優(yōu)化設(shè)計(jì)方法。首先,按近似概率極限狀態(tài)設(shè)計(jì)法的基本思想,利用分項(xiàng)系數(shù)對(duì)風(fēng)致響應(yīng)和自重響應(yīng)進(jìn)行組合,進(jìn)行輸電塔失效模式識(shí)別,得到主要失效模式及其關(guān)鍵桿件。然后,找出那些承載力不足的失效模式及其對(duì)應(yīng)的關(guān)鍵桿件。最后,對(duì)這些關(guān)鍵桿件進(jìn)行優(yōu)化。編制程序?qū)崿F(xiàn)了某輸電塔不同風(fēng)速下的自動(dòng)優(yōu)化。近似概率極限狀態(tài)設(shè)計(jì)法是目前工程界較為流行的近似處理工程可靠度的方法,為包括我國(guó)在內(nèi)的多國(guó)規(guī)范所用,為工程技術(shù)人員所熟知。該優(yōu)化方法繞過了繁瑣的可靠度計(jì)算而能滿足可靠度的要求。 (4)提出一種計(jì)算量相對(duì)較少可應(yīng)用于工程實(shí)際的基于體系可靠度優(yōu)化設(shè)計(jì)法。首先,求出各個(gè)失效模式可靠指標(biāo),對(duì)不滿足要求的失效模式通過加強(qiáng)關(guān)鍵桿件的方法來提高可靠指標(biāo)直到滿足為止。然后,綜合各個(gè)失效模式,得到體系可靠指標(biāo)。最后,若體系可靠指標(biāo)不滿足要求,通過提高最小可靠指標(biāo)的那種失效模式可靠指標(biāo)的方法來提高體系可靠指標(biāo)直到滿足為止。編制程序?qū)崿F(xiàn)了某輸電塔若干風(fēng)速下的自動(dòng)優(yōu)化。相對(duì)傳統(tǒng)的可靠度優(yōu)化,該方法計(jì)算量少,可用于實(shí)際復(fù)雜結(jié)構(gòu)的基于體系可靠度的優(yōu)化設(shè)計(jì)。與本文前一種優(yōu)化方法比較,優(yōu)化更加經(jīng)濟(jì)合理。
[Abstract]:According to the statistical analysis of a large number of transmission towers under the action of strong wind, it is found that the structure design of various types of transmission towers is not reasonable from the angle of wind resistance. There are typical vulnerable components, weak parts and wind destruction modes of the transmission tower structure under strong wind. Therefore, how to increase the structure material as little as possible On the basis of it, it is of great value to improve the wind resistance of the tower structure. That is to say, the wind resistance optimization design of the transmission tower is of great engineering significance, the long-term social effect and the broad application prospect.
The calculation of wind induced response is the prerequisite for the optimization design of transmission tower. At present, the wind load theory model of the transmission tower line system has not been established, and the wind tunnel test can only get the wind response of the representative test points. The wind load inversion is also a problem that the wind load is assumed to be incompatible with the actual situation. Second, from the overall point of view, the uncertainty in engineering is not considered.
In view of the shortcomings of wind resistance optimization design of transmission tower, on the basis of predecessors, this paper studies the optimization design of transmission towers on the basis of the calculation of the equivalent wind load and the analysis of the wind destruction mode, and on the basis of the analysis of the multiple factors in the project.
(1) the wind response of each component is obtained by fitting the displacement response of the test point of the wind tunnel test. First, the average value of the displacement response of the measuring point obtained by the wind tunnel test of the single tower is fitted to get the shape coefficient of the transmission tower. The displacement response average of the test point obtained from the wind tunnel test of the tower line system and the displacement of the single tower wind tunnel test under the corresponding wind speed are obtained. In response to the difference of the average value, the shape coefficient of the line is obtained. Then, the variance of the displacement response of the CIS wind direction measured by the wind tunnel test from the tower line system wind tunnel test is obtained. The covariance is fitted to the generalized displacement variance of the first mode of the CIS wind direction to the tower, and the horizontal displacement of the cross wind direction obtained by the tower line system wind tunnel test is obtained. In the response time, the variance of the displacement response of each crosswind to the measurement point is obtained, and the covariance is used to fit the generalized displacement variance of the first mode of the first mode dominated by the tower. Finally, the average wind load is added to the finite element model to get the average response of each component, and the response of the corresponding wind to the first mode corresponds to the response of the transverse wind to the first mode. The root mean square of the response of the component is obtained, and the wind-induced response of each component is obtained by adding the peak value of the mean square root of the mean response.
(2) the failure modes and Countermeasures of the transmission tower under strong wind are carried out. First, the wind induced response is obtained by the above method, and the failure mode identification of the transmission tower is considered together with the self weight response, the main failure mode and its ultimate wind speed are obtained. The calculation results are compared with the actual inverted tower cases. Then, two kinds of transmission towers are developed to improve the transmission tower resistance. The first countermeasure is to reinforce the weak parts of the wind induced failure of the transmission tower and improve its wind resistance. The transmission tower has been strengthened 3 times in this paper. The second countermeasures are to improve the wind resistance by optimizing the design parameters of the key rod. Optimization.
(3) the optimal design method of transmission tower based on ultimate bearing capacity is proposed. Firstly, according to the basic idea of the approximate probability limit state design method, the failure mode of transmission tower is identified and the main failure modes and the key members are obtained by combining the fractional coefficient to the combination of the wind response and the self weight response. Then, the lack of the bearing capacity is found out. The failure mode and its corresponding key rod. Finally, the key members are optimized. The programming is made to realize the automatic optimization of a transmission tower under different wind speeds. The approximate probability limit state design method is a popular method to approximate the engineering reliability in engineering circles at present, which is used for many countries including our country. It is well known that the optimization method can bypass the tedious reliability calculation and meet the reliability requirements.
(4) a system reliability optimization design method, which can be applied to engineering practice, is proposed. First, the reliability index of each failure mode is obtained, and the failure mode which is not satisfied is improved by the method of strengthening the key rod to improve the reliability index until it is satisfied. Then, the system can be synthesized and the system can be synthesized. In the end, if the reliability index of the system is not satisfied, the reliability index of the failure mode is improved by improving the reliability index of the failure mode of the minimum reliability index until it is satisfied. The programming has realized the automatic optimization of a certain transmission tower under several wind speeds. The optimal design based on system reliability for practical complex structures is more economical and reasonable compared with the previous optimization method.
【學(xué)位授予單位】:武漢大學(xué)
【學(xué)位級(jí)別】:博士
【學(xué)位授予年份】:2014
【分類號(hào)】:TU347;TM753
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