本文選題：直擊雷　切入點：桁架橋梁　出處：《河北工業(yè)大學(xué)》2015年博士論文　論文類型：學(xué)位論文

【摘要】：隨著我國國民經(jīng)濟(jì)的快速增長,橋梁技術(shù)作為交通建設(shè)中必不可少部分也得到迅速發(fā)展。由于大跨度橋梁多位于水陸交界處,地勢空曠,是雷暴極易發(fā)生的區(qū)域,因此,對橋梁雷電瞬態(tài)電磁現(xiàn)象及相關(guān)效應(yīng)進(jìn)行準(zhǔn)確的分析是橋梁防雷設(shè)計中不可缺少的環(huán)節(jié)。本文結(jié)合國家重點基礎(chǔ)研究發(fā)展計劃(973計劃)前期研究專項的要求,開展了對桁架橋梁在遭遇直擊雷時雷電防護(hù)系統(tǒng)中瞬態(tài)電磁現(xiàn)象的深入研究,并對直擊雷條件下桁架橋梁的電磁效應(yīng)、電動力和熱效應(yīng)進(jìn)行了定量評估。主要的研究內(nèi)容如下:1、提出了基于耦合傳輸線網(wǎng)絡(luò)模型的桁架橋防雷系統(tǒng)的建模方法,在頻域內(nèi)采用迭代的方法對桁架橋耦合傳輸線網(wǎng)絡(luò)方程進(jìn)行求解,得到了分支導(dǎo)體中電流分布;經(jīng)過與試驗結(jié)果和其它方法計算結(jié)果的對比表明:本方法不僅在計算精度上達(dá)到了工程要求,而且在求解速度和運(yùn)算量兩個方面明顯優(yōu)于其它方法。本方法為快速計算桁架橋內(nèi)部雷電瞬態(tài)磁場分布奠定了基礎(chǔ)。2、根據(jù)得到的桁架橋金屬構(gòu)架上的瞬態(tài)電流分布,考慮不同分段上的電流對空間作用點的時延,得到空間的動態(tài)磁失量位函數(shù)分布,進(jìn)而提出了利用差分法計算桁架橋內(nèi)部空間磁場分布的方法,該方法適合大尺寸桁架橋梁電磁瞬態(tài)現(xiàn)象的快速分析計算。3、在試驗驗證方面,制作了用于瞬態(tài)磁場測量的磁場探測線圈,并對測量線圈進(jìn)行了標(biāo)定。針對遠(yuǎn)端測量點上磁場較弱、受干擾嚴(yán)重的情況,采用小波降噪手段還原真實信號,解決了測量中的實際困難。理論與試驗相結(jié)合,討論了雷擊點位置對磁場分布的影響,雷擊點在頂邊中點時構(gòu)架上的電流分布遠(yuǎn)比雷擊頂面角點位置時均勻,因而此種情況下內(nèi)部磁場分布也更加均勻。4、將電動力和熱效應(yīng)試驗應(yīng)用于桁架橋縮比模型中,直觀的評估了雷電電動力和熱效應(yīng)對桁架橋縮比模型的損傷程度;電動力造成的機(jī)械性損傷并不嚴(yán)重;雷電的熱損傷主要表現(xiàn)為接閃點處的雷電電弧燒蝕作用,而雷電流造成的阻性溫升并不會對桁架橋自身造成危害。
[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.
【學(xué)位授予單位】：河北工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：U447;TM862

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