钢管混凝土柱冲击动力响应的等效单自由度方法研究

发布时间：2018-10-04 19:10

【摘要】：钢管混凝土结构凭借承载力高、抗震性能优越、施工简便等诸多优点在工程项目中得到广泛应用。作为承重构件的钢管混凝土柱如果遭受到横向冲击等偶然荷载作用,将会造成重大的人员伤亡和财产损失。本文先采用LS-DYNA有限元软件对轴压作用下的钢管混凝土柱的抗冲击性能展开研究,然后基于等效单自由度方法,计算钢管混凝土柱的冲击动力响应。研究内容如下:1.根据试验结果,验证了 LS-DYNA软件计算的可靠性。然后建立了两种不同钢管壁厚的构件有限元模型。计算结果发现,当冲击高度较小时,在一定的轴压比范围内,适当施加轴力能够提高钢管混凝土构件的抗冲击性能;当冲击高度较大时,即使在较小的轴压比范围内,轴力的存在也会急剧削弱钢管混凝土构件的抗冲击性能。2.从仿真结果可以看出,轴压作用下的钢管混凝土柱的冲击力时程曲线一般分为具有平台段和没有平台段两种形式,为了便于等效单自由度方法的计算,按照冲量相等的原则将实际复杂的冲击力时程曲线简化为矩形脉冲和三角形脉冲形式,在一定情况下得到的位移误差较小。3.推导了轴压作用下钢管混凝土柱受跨中冲击等效单自由度体系的运动微分方程,并给出了矩形脉冲和三角形脉冲荷载的位移响应通解。采用等效单自由度方法计算了各种仿真工况的位移响应,对比位移最大值发现,当冲击速度较小时,一般可以将冲击力时程简化成矩形脉冲荷载,此时得到的最大位移值与LS-DYNA的仿真结果误差较小;当冲击速度较大时,一般需要将冲击力时程简化成三角形脉冲荷载,此时计算结果的误差比矩形脉冲相对较大;在小轴压范围内,轴压比增大时,误差会减小;增加钢管厚度,结构产生的位移减小,误差也减小。
[Abstract]:Concrete filled steel tube (CFST) structure is widely used in engineering projects by virtue of its high bearing capacity, superior seismic performance and easy construction. Concrete-filled steel tubular columns as load-bearing members will cause heavy casualties and property losses if they are subjected to accidental loads such as lateral impact. In this paper, the impact resistance of concrete-filled steel tubular columns under axial compression is studied by using LS-DYNA finite element software, and then the impact dynamic response of concrete filled steel tubular columns is calculated based on the equivalent single-degree-of-freedom method. The research is as follows: 1. According to the experimental results, the reliability of LS-DYNA software calculation is verified. Then two kinds of finite element models of steel tube with different wall thickness are established. The results show that when the impact height is small and the axial compression ratio is within a certain range, the proper application of axial force can improve the impact resistance of concrete-filled steel tubular members, and when the impact height is large, even in a small axial compression ratio range, The impact resistance of concrete filled steel tubular (CFST) members will be greatly weakened by the existence of axial force. From the simulation results, it can be seen that the impact time history curve of concrete-filled steel tubular columns under axial compression is generally divided into two forms: the stage section and the non-platform section. In order to facilitate the calculation of the equivalent single-degree of freedom method, According to the principle of equal impulse, the actual complex time history curve of impact force is simplified into rectangular pulse and triangular pulse, and the displacement error is smaller. 3. The differential equations of motion of concrete-filled steel tubular columns under axial compression are derived and the displacement responses of rectangular and triangular impulsive loads are given. The displacement response of various simulation conditions is calculated by using the method of equivalent single degree of freedom. By comparing the maximum displacement with the maximum displacement, it is found that when the impact velocity is small, the time history of impact force can be simplified into rectangular pulse load. When the impact velocity is large, the time history of impact force should be simplified as triangular pulse load, and the error of the calculated result is larger than that of rectangular pulse. In the small axial compression range, when the axial compression ratio increases, the error will decrease, and the displacement and error of the structure will decrease with the increase of the steel tube thickness.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU398.9

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