直杆叠积螺旋空间结构的找形分析方法

Form-finding analysis method for spiral spatial structures with stacked members

为了提高原竹结构承载力与安装便利性,提出仅需通过绑扎连接且空间形态丰富的直杆叠积螺旋空间结构.新型结构的杆件数量和每根杆件叠积点的竖向坐标取决于各杆件的几何尺寸与下部杆件的空间位置,据此提出几何建模编程方法:用空间解析几何方法建立方程组,用迭代法求解超越方程,用多项式回归法拟合各杆件坐标;并提出简捷有效的逆向安装方法,以避免竹子直径和安装误差对结构形状的不利影响.工程实践证明了新型结构的找形分析方法的正确性和逆向安装方法的可行性.受力分析算例结果表明,开口形新型结构斜向杆的最大应力受弯矩控制,环向杆上的轴力显著大于斜向杆.

A spiral spatial structure,featuring in stacked members,various structural styles and binding joints,was proposed to improve the bearing capacity and installation convenience of bamboo structures.Usually,the total number and spatial location of members for the new-type structure depend on both the geometrical dimensions of members and the location of members which has been stacked.According to this,a form-finding method for the structure was proposed,which established equations with spatial geometric modeling,solved transcendental equation by iterative method,and fitted coordinate curves with polynomials.Through a simple and effective reverse installation method,adverse effect caused by bamboo diameter and installation errors was avoided.Engineering practice shows that the form-finding analysis is correct and the reverse installation method is feasible.The analysis results indicate that the maximum stress of the diagonal members in the structure is caused by bending moment,and the axial force on the circle members is greater than that of the diagonal members.