中文摘要：

以某实际张弦立体桁架结构为基础,通过在结构中布置不同数量的连系桁架形成4个计算模型.计算这4个模型在不同矢高、垂距、桁架高度、拉索截面及其预应力情况下的失稳模式,结果显示所有情况下结构失稳时立体桁架均发生明显的扭转变形.利用理论分析方法及有限元法研究立体桁架的抗扭刚度及其对结构稳定性的影响,发现张弦立体桁架结构的稳定承载力会随着立体桁架扭转刚度的增加而增加.当立体桁架上弦仅有横向支撑时,结构的扭转刚度主要取决于横撑的弯曲刚度,此时须保证横撑与主管刚性连接,否则立体桁架在扭矩作用下可能形成局部瞬变体系而丧失抗扭转能力.在横撑基础上附加斜向支撑是解决瞬变问题的有效方法,研究表明斜撑可以极大地提高结构的抗扭刚度,进而提升张弦立体桁架结构的整体稳定承载力.

英文摘要：

Based on a practical engineering,four structural models which have different numbers of subsidiary trusses are captured.Failure models of the structures,under different vector high,truss height,prestressed,cable-vertical distance and sectional area,are analyzed,which indicates that the spatial truss must suffer torsional deformation while the structure is losing stability.Relationship between torsion stiffness and stability of the spatial truss string structure is researched by both theoretical method and finite element method,the result is that stability capacity of the structure can be advanced through the enhancement of its torsion stiffness.If there is only lateral brace in structure,the torsion stiffness largely depends on the bending stiffness of the lateral brace,which must be connected with the chord members rigidly,otherwise the structure may lose the resistance to torque for that it may become a transient system under torsional loading.Disposal of additional diagonal brace between the chord members is an effective method to solve the problem,research results show that the diagonal brace can greatly enhance torsion stiffness and stability capacity of the structure.