基于输电塔风毁模式的结构优化设计研究

发布时间：2018-06-29 19:13

本文选题：输电塔 + 优化设计　；参考：《武汉大学》2014年博士论文

【摘要】：对大量输电塔在强风作用下的倒塔事故进行统计分析可知,目前多种类型输电塔的结构设计从抗风性能的角度来看不尽合理。输电塔结构在强风作用下存在典型的易损构件、薄弱部位和风毁模式。因此,如何在尽可能少地增加结构材料的基础上大大提高塔结构的抗风性能就成为极有研究价值的课题,也就是说,输电塔抗风优化设计研究是具有重要的工程意义、长远的社会效应和广阔的应用前景的研究课题。风致响应的计算是输电塔优化设计的前提。目前,输电塔线体系风荷载理论模型尚未建立,风洞试验也仅能得到代表性测点的风致响应,风荷载反演中又存在风荷载形式假定与实际不符的问题。目前,输电塔的优化大多数是基于构件层次的,从整体角度优化时又未能考虑工程中的不确定性。针对目前输电塔抗风优化设计中存在的不足,在前人基础上,本文在等效风荷载计算和风毁模式分析的基础上同时考虑工程中多因素的不确定性对输电塔的优化设计进行研究。具体地说,本文的研究工作主要包括以下几个方面： (1)从风洞试验的测点位移响应拟合得到各个构件的风致响应。首先,由单塔的风洞试验得到的测点位移响应平均值拟合得到输电塔体型系数,由塔线体系的风洞试验得到的测点位移响应平均值与对应风速下单塔风洞试验测点的位移响应平均值的差得到线的体型系数。然后,由塔线体系风洞试验得到的顺风向测点位移响应时程得到各顺风向测点位移响应的方差、协方差,拟合顺风向以塔为主的第一模态的广义位移方差,由塔线体系风洞试验得到的横风向测点位移响应时程得到各横风向测点位移响应的方差、协方差,拟合横风向以塔为主的第一模态的广义位移方差。最后,把平均风荷载加到有限元模型上得到各个构件的平均响应,把顺风向第一模态对应的响应与横风向第一模态对应的响应进行组合得到构件响应的均方根,把平均响应叠加峰值倍均方根即得到各个构件的风致响应。 (2)进行了输电塔在强风作用下的失效模式及对策研究。首先,按上述方法得到风致响应,与自重响应一起考虑进行输电塔失效模式识别,得到主要失效模式及其极限风速,计算结果与实际倒塔案例相比较。然后,发展了两种提高输电塔抗风承载力的对策。第一种对策是对输电塔风致破坏的薄弱部位进行加固,提高其抗风承载力,文中输电塔进行了3次加固。第二种对策是通过优化关键杆件的设计参数来提高其抗风承载力。通过编制程序,.实现了某输电塔若干风速的自动优化。 (3)提出了基于极限承载力的输电塔优化设计方法。首先,按近似概率极限状态设计法的基本思想,利用分项系数对风致响应和自重响应进行组合,进行输电塔失效模式识别,得到主要失效模式及其关键杆件。然后,找出那些承载力不足的失效模式及其对应的关键杆件。最后,对这些关键杆件进行优化。编制程序实现了某输电塔不同风速下的自动优化。近似概率极限状态设计法是目前工程界较为流行的近似处理工程可靠度的方法,为包括我国在内的多国规范所用,为工程技术人员所熟知。该优化方法绕过了繁琐的可靠度计算而能满足可靠度的要求。 (4)提出一种计算量相对较少可应用于工程实际的基于体系可靠度优化设计法。首先,求出各个失效模式可靠指标,对不满足要求的失效模式通过加强关键杆件的方法来提高可靠指标直到满足为止。然后,综合各个失效模式,得到体系可靠指标。最后,若体系可靠指标不满足要求,通过提高最小可靠指标的那种失效模式可靠指标的方法来提高体系可靠指标直到满足为止。编制程序实现了某输电塔若干风速下的自动优化。相对传统的可靠度优化,该方法计算量少,可用于实际复杂结构的基于体系可靠度的优化设计。与本文前一种优化方法比较,优化更加经济合理。
[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.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU347;TM753

【参考文献】