考虑荷载分布模式的弯剪型结构最优刚度分布解析研究

ANALYTICAL STUDY ON OPTIMAL STIFFNESS DISTRIBUTION OF BEND-SHEAR STRUCTURES CONSIDERING LOAD DISTRIBUTION

  • 摘要: 如果结构在外部激励下产生均匀损伤或均匀变形,则可避免出现薄弱层且可提高承载能力和安全性,以此为目标进行结构优化具有重要意义。将弯剪型结构简化为连续变截面悬臂杆,假定结构截面函数具有自然指数型和幂函数型等形式,将地震和风荷载等外部激励等效为均布、倒三角和惯性相关等三种荷载分布模式。根据均匀变形准则将结构绝对位移曲线关于高度的二次导数为零作为优化目标,建立结构连续化位移方程并进行优化求解,获得了考虑荷载分布形式的弯剪型结构最优刚度和截面分布解析解。理论和数值分析结果表明:截面按幂函数变化的结构能够实现均匀损伤,不同荷载分布模式下的最优刚度或截面分布有所不同。有限元静动力分析结果进一步验证了解析解的准确性和实用性。

     

    Abstract: For structures subjected to external excitation, the weak layers can be avoided and the bearing capacity and safety can be improved if all the damage degrees or the relative displacements of each story are the same, i.e., the uniform damage or uniform deformation occurs. It is significant to carry out structural optimization with uniform damage as the optimization objective. The bend-shear structure is simplified as a continuous variable cross-section cantilever. The assumed cross section functions include the forms of a natural exponential function and a power function. The external excitation such as earthquake effects and wind loads are idealized to three load modes, that is, the uniform distribution, the inverted triangle distribution and the inertia correlation distribution. According to the uniform deformation criterion, to make the second derivative of the absolute displacement curve of the structure equals zero is taken as the optimization target. The continuous displacement equation is established and the optimization results are discussed. The analytical solution of the optimal stiffness and the cross section distribution of the bend-shear structure is obtained. According to the theoretical and numerical results, the uniform damage can be realized if the cross section function is taken as power function, and the optimal distributions of stiffness and cross sections are different for different load distribution modes. The accuracy and the practicability of the analytical solution is verified by static-dynamic analysis based on the finite element method.

     

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