圆形福建土楼模态分析

Modal Analysis of Circular Fujian Tulou

为了研究福建土楼的动力特性,运用有限元数值模拟方法,将土楼简化为外部夯土结构、夯土-木构混合结构两种模型,并对模型进行模态分析;研究夯土弹性模量、夯土密度、夯土墙高度、土楼结构平均半径及夯土墙平均厚度等5个因素对土楼外部夯土结构自振频率的影响.结果表明:夯土结构自振频率随着夯土弹性模量、夯土墙平均厚度的增加而增加,随着夯土密度、夯土墙高度、土楼结构平均半径的增加而减小;夯土结构自振频率与夯土弹性模量的平方根近似成正比,与夯土密度的平方根及夯土墙高度近似成反比;不同阶自振频率曲线发生重合现象,说明圆形土楼夯土结构可能存在密频现象,也说明材料特性变化对不同阶自振频率的影响基本一致;土楼结构平均半径和夯土的弹性模量的参数敏感性最大,夯土密度的参数敏感性较小.

Tulou was simplified into two models including external rammed earth structure and rammed earth-timber mixed structure,the finite element simulation method was used to analyze the dynamic modal characteristics of Fujian Tulou models.The influence on natural frequency of external rammed earth structure was studied by 5 factors including the elastic modulus,density of rammed earth,the height,the average radius of structure of Tulou,and the average thickness of the rammed earth wall.The results show that the natural frequency of the structure increases with the increase of the elastic modulus of rammed earth and the thickness of the rammed earth wall,decreases with the increase of the density of rammed earth,height of Tulou,and average radius of structure of Tulou.The natural frequency of rammed earth is approximately proportional to the square root of the elastic modulus of rammed earth,and is inversely proportional to the square root of the density of rammed earth and the height of Tulou.The natural frequency curves of different orders coincide,indicating that there may be dense frequency phenomena in the rammed earth structure of circular Tulou,and the influence of the change of material properties on natural frequencies of different orders was similar.The parameters of the average radius and elastic modulus of rammed earth are the most sensitive,the parameter of rammed earth density is little sensitive.