基于三维力学分析模型与灵敏度方法的古建筑木结构模型修正

MODIFICATION OF ANCIENT WOODEN STRUCTURE MODEL UPON THREE-DIMENSIONAL MECHANICAL ANALYSIS MODEL AND SENSITIVITY METHOD

  • 摘要: 古建筑木结构材料离散性强、连接构造复杂,同时存在多种类型的损伤,因此很难建立与实际结构吻合度高的分析模型。为解决上述问题,提出了一种基于三维力学分析模型与灵敏度方法的古建筑木结构模型修正方法。构建了由梁、柱单元和能够反映柱脚、榫卯等关键节点构造特征的半刚度节点单元组合而成的混合单元模型,进而建立了古建筑木结构三维力学分析模型,由实体有限元模型的验证结果可知,提出的分析模型可有效反映理想无损结构的受力变形特征;根据古建筑木结构长期监测数据表明的应变-温度的强相关关系,提出了基于温度-应变监测数据的混合单元刚度参数修正方法,以三维力学分析模型作为初始模型,利用高斯牛顿迭代法求解灵敏度方程得到刚度参数修正值,得到可反映实际损伤结构的古建筑木结构修正模型;基于数值模拟验证了所提方法的有效性。结果表明:当噪声水平为5%时,修正模型刚度参数与实际刚度参数的相对误差仅为3.36%,具有较好的噪声鲁棒性。

     

    Abstract: For an ancient wooden structure, it is difficult to establish an analysis model which have a high degree of agreement with the actual structure because of the discrete nature of materials, of complex connection structures, and of the presence of multiple types of damage. To solve above problems, proposed is a modification method for establishing an ancient building wood structural model upon the three-dimensional mechanical analysis and sensitivity methodology. Constructed is a hybrid element model consisting of beam and column elements and semi-rigid nodal elements reflecting the structural characteristics of key joints, and then established is a three-dimensional mechanical analysis model for the ancient wooden structure. The validation results of the fine numerical model of full entity element show that the analysis model proposed can effectively reflect the force-deformation characteristics of the ideal non-damaged structure. A hybrid element stiffness modification method based on the temperature-strain monitor data is proposed, according to the strong correlation of strain-temperature indicated by the long-term monitor data of the ancient wooden structure. The method takes the three-dimensional mechanical analysis model as the initial model, and the Gauss-Newton iterative method is used to solve the sensitivity equation to obtain the correction value of the stiffness parameter, and then the modified model of ancient building wood structure that can reflect the actual damaged structure is obtained. The effectiveness of the method proposed is verified with numerical simulations. The results show that when the noise level is 5%, the relative error between the modified model stiffness and the actual stiffness is only 3.36%, indicating the method has good noise robustness.

     

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