直击雷条件下桁架桥梁防雷系统模型的建立及相关效应研究

发布时间：2018-03-09 05:28

本文选题：直击雷　切入点：桁架桥梁　出处：《河北工业大学》2015年博士论文　论文类型：学位论文

【摘要】：随着我国国民经济的快速增长,桥梁技术作为交通建设中必不可少部分也得到迅速发展。由于大跨度桥梁多位于水陆交界处,地势空旷,是雷暴极易发生的区域,因此,对桥梁雷电瞬态电磁现象及相关效应进行准确的分析是桥梁防雷设计中不可缺少的环节。本文结合国家重点基础研究发展计划(973计划)前期研究专项的要求,开展了对桁架桥梁在遭遇直击雷时雷电防护系统中瞬态电磁现象的深入研究,并对直击雷条件下桁架桥梁的电磁效应、电动力和热效应进行了定量评估。主要的研究内容如下:1、提出了基于耦合传输线网络模型的桁架桥防雷系统的建模方法,在频域内采用迭代的方法对桁架桥耦合传输线网络方程进行求解,得到了分支导体中电流分布;经过与试验结果和其它方法计算结果的对比表明:本方法不仅在计算精度上达到了工程要求,而且在求解速度和运算量两个方面明显优于其它方法。本方法为快速计算桁架桥内部雷电瞬态磁场分布奠定了基础。2、根据得到的桁架桥金属构架上的瞬态电流分布,考虑不同分段上的电流对空间作用点的时延,得到空间的动态磁失量位函数分布,进而提出了利用差分法计算桁架桥内部空间磁场分布的方法,该方法适合大尺寸桁架桥梁电磁瞬态现象的快速分析计算。3、在试验验证方面,制作了用于瞬态磁场测量的磁场探测线圈,并对测量线圈进行了标定。针对远端测量点上磁场较弱、受干扰严重的情况,采用小波降噪手段还原真实信号,解决了测量中的实际困难。理论与试验相结合,讨论了雷击点位置对磁场分布的影响,雷击点在顶边中点时构架上的电流分布远比雷击顶面角点位置时均匀,因而此种情况下内部磁场分布也更加均匀。4、将电动力和热效应试验应用于桁架桥缩比模型中,直观的评估了雷电电动力和热效应对桁架桥缩比模型的损伤程度;电动力造成的机械性损伤并不严重;雷电的热损伤主要表现为接闪点处的雷电电弧烧蚀作用,而雷电流造成的阻性温升并不会对桁架桥自身造成危害。
[Abstract]:With the rapid growth of our national economy, bridge technology, as an essential part of traffic construction, has been developed rapidly. Accurate analysis of lightning transient electromagnetic phenomena and related effects is an indispensable link in bridge lightning protection design. In this paper, the transient electromagnetic phenomena in the lightning protection system of truss bridges under direct lightning strike are deeply studied, and the electromagnetic effects of truss bridges under direct lightning strike are also studied. The main research contents are as follows: 1. A modeling method for lightning protection system of truss bridge based on coupled transmission line network model is proposed. The coupled transmission line network equation of truss bridge is solved by iterative method in frequency domain, and the current distribution in branch conductor is obtained. The comparison with the experimental results and other calculation results shows that this method not only meets the engineering requirements in terms of calculation accuracy, This method lays a foundation for fast calculation of lightning transient magnetic field distribution in truss bridge, according to the transient current distribution on metal frame of truss bridge. Considering the time delay of the current acting on the space in different sections, the spatial distribution of the dynamic magnetic loss potential function is obtained, and the method of calculating the spatial magnetic field distribution of the truss bridge by using the difference method is proposed. This method is suitable for the fast analysis and calculation of electromagnetic transient phenomena of large-sized truss bridges. In the aspect of test and verification, a magnetic field detecting coil for transient magnetic field measurement is made. The measurement coil is calibrated. In view of the weak magnetic field and serious interference on the remote measurement point, the real signal is restored by wavelet denoising method, which solves the practical difficulties in the measurement. The effect of lightning point position on magnetic field distribution is discussed. The distribution of current on the frame is much more uniform than that at the corner point of the top surface when the lightning strike point is at the middle point of the top edge. Therefore, the distribution of magnetic field is more uniform in this case. The electric force and thermal effect test is applied to the shrinkage ratio model of truss bridge, and the damage degree of lightning electric force and thermal effect to the shrinkage ratio model of truss bridge is evaluated intuitively. The mechanical damage caused by electric force is not serious, the thermal damage of lightning is mainly caused by the ablation of lightning arc at the flash point, and the resistance temperature rise caused by lightning current will not cause harm to the truss bridge itself.
【学位授予单位】：河北工业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U447;TM862

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