为进一步探索空腹索桁张力结构初始预应力分布、静力性能及误差敏感性,在理论分析的基础上,设计加工了一直径5m的结构模型.提出了该模型支承平台、可调索杆、连接节点等加工制作方案及基于最小二乘法的各测点内力-应变关系拟合方法,考察了张拉各构件到设计长度时的体系初始预应力分布,模型在满跨、半跨和1/4跨等多种荷载工况下的静力响应及通过调整杆件长度模拟杆长误差以考察长度的误差敏感性.研究表明,当所有构件都张拉到设计长度时,空腹索桁张力结构初始预应力分布将达到设计值;结构在不对称荷载作用下易发生平面外失稳,平面外刚度较差,而在整体均布荷载作用下表现出良好的承载性能;环索长度误差敏感性最明显,脊索、斜索次之,桅杆最弱.初内力分布、多种荷载工况下的静力响应及误差敏感性分析理论值与实测值基本吻合,表明了理论分析的正确性和模型设计的有效性.
In order to investigate pre-stress distribution, static behaviour and error sensitivity based on theoretical analysis, a cable-strut tensile structure model with a diameter of 5.0 meter was fabricated. New schemes for the boundary compression ring, the cables and struts with adjustable lengths and the connection nodes were designed. The least square method which fit the relationship between the element internal force and strain was proposed. Initial pre-stress distribution and static responses of the model under three different loading conditions, such as full-span loading, half-span loading and 1/4-span loading conditions, were investigated. Finally the element length error sensitivity was simulated by adjusting the element lengths. The experimental results indicated that the cable-strut tensile structure achieved the designed initial pre-stress distribution while all the elements were tensioned to the designed lengths. The whole system performed good bearing capacity under uniform loadings while its stability and out-of-plane stiffness were weak when subjecting to unsymmetrical loadings. Error sensitivity of the hoop cable was the most sensitive. And it turned lower in the case of ridge cables and diagonal cables, while the struts were of the lowest error sensitivity. The experimental results also showed that the initial pre-stress distribution, static responses and the error sensitivity performed almost consistently with the theoretical results, which proves validity and accuracy of the theoretical analysis and the model design.