高层建筑结构雷电冲击模型建立及其求解方法研究

发布时间：2018-10-15 09:13

【摘要】：随着城市用地的减少和城市人口的不断增加,高层建筑不断涌现,然而高层建筑更容易成为雷击目标。因此为全面了解雷击后高层建筑物内的电磁暂态现象,本文建立了考虑高耸物体顶部和底部反射系数的雷电冲击电流数学模型,提出了基于有限元方法的求取建筑物钢筋结构体电流分布及建筑物内部空间位置的磁场分布的三维电磁耦合模型,提出了基于有限元的三维电-热耦合模型,并将建筑物模型简化为单根圆柱导体来分析其温度分布,对一个五层建筑物缩比模型的电流分布、磁场分布、温度分布及电动力效应进行了试验研究。首先,研究了雷电回击的传输线模型表示的雷击高耸物体后的暂态行为,提出了集总电压源模型、分布电流源模型和诺顿等效电路模型表示的雷电通道及高耸物体中的雷电流的数学公式。仿真分析了用集总电压源模型和分布电流源模型表示的雷击平坦地面和雷击高耸物体的电流波形、高耸物体顶部和底部反射系数对电流波形的影响及高耸物体对首次和后续回击电流的影响。其次,研究了雷击下高层建筑物的电流和磁场分布,建立了参数化的高层建筑物雷电冲击仿真模型,并用一个典型建筑物模型作为算例,对不同计算方法得出的结果进行了比较。提出同轴对称多回路导体测试结构,试验研究了五层建筑物缩比模型钢筋结构体电流分布,并测量了建筑物模型顶层、第四层和底层各六个空间位置点的磁感应强度,将试验研究结果与提出的电磁耦合模型仿真结果比较,发现两者电流分布吻合较好,而磁感应强度略有差别,但两者分布趋势相同。最后,研究了高层建筑物的热效应和电动力效应,试验研究了五层建筑物缩比模型遭受相同幅值不同电荷量长冲击电流后的温度分布,试验结果与提出的基于有限元的电-热耦合模型仿真结果吻合,并仿真分析了长冲击电流幅值和转移电荷量与温升的关系,为解决此类问题提供了试验及理论依据。同时,试验研究了五层建筑物缩比模型受不同幅值的冲击电流作用下的破坏程度,结果表明冲击电流幅值虽大,但因其持续时间短不会对建筑物钢筋结构体造成破坏。
[Abstract]:With the decrease of urban land and the increasing of urban population, high-rise buildings are emerging constantly, however, high-rise buildings are more likely to be the target of lightning strike. In order to fully understand the electromagnetic transient phenomena in high-rise buildings after lightning strike, a mathematical model of lightning impulse current considering the reflection coefficients of the top and bottom of towering objects is established in this paper. A three-dimensional electromagnetic coupling model based on finite element method is proposed to calculate the current distribution of the reinforcement structure and the magnetic field distribution in the space of the building, and a three-dimensional electric-thermal coupling model based on the finite element method is proposed. The structure model is simplified as a single cylindrical conductor to analyze its temperature distribution. The current distribution, magnetic field distribution, temperature distribution and electrodynamic effect of a five-story building shrinkage model are studied experimentally. Firstly, the transient behavior of a towering object after lightning strike is studied by the transmission line model of lightning return stroke, and a lumped voltage source model is proposed. The mathematical formula of lightning current in lightning channel and towering object expressed by distributed current source model and Norton equivalent circuit model. The current waveforms of lightning strike flat ground and lightning towering objects expressed by lumped voltage source model and distributed current source model are simulated and analyzed. The effect of reflection coefficient at the top and bottom of the towering object on the current waveform and the effect of the towering object on the first and subsequent backstroke current. Secondly, the distribution of current and magnetic field of high-rise buildings under lightning strike is studied, and a parameterized simulation model of lightning shock of high-rise buildings is established, and a typical building model is used as an example. The results obtained by different calculation methods are compared. A coaxial symmetric multi-loop conductor test structure is proposed. The current distribution of the reinforcement structure of the five-story building shrinkage model is experimentally studied. The magnetic induction intensity of the top layer, the fourth floor and the bottom layer of the building is measured. By comparing the experimental results with the simulation results of the proposed electromagnetic coupling model, it is found that the current distribution of the two models is in good agreement with that of the electromagnetic coupling model, while the magnetic induction intensity is slightly different, but the distribution trend of the two is the same. Finally, the thermal and electrodynamic effects of high-rise buildings are studied, and the temperature distribution of the five-story building model subjected to shock current with the same amplitude and different charge is experimentally studied. The experimental results are in good agreement with the simulation results of the electro-thermal coupling model based on finite element method, and the relationship between the amplitude of long impulse current and the amount of transfer charge and temperature rise is simulated and analyzed, which provides the experimental and theoretical basis for solving this kind of problem. At the same time, the damage degree of the five-story building shrinkage model under the action of shock current with different amplitude is studied. The results show that although the amplitude of impact current is large, the short duration of the shock current will not cause damage to the reinforced structure of the building.
【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】：TU976.55

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