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张弦梁结构作为一种自平衡体系,在大跨度屋盖结构中得到日益广泛的应用。设计状态下张弦梁上弦构件受到檩条、支撑等屋面结构的约束,其平面外稳定问题并不显著。但在施工过程中对平面张弦梁进行预张拉时,一般要设置临时面外支撑,因此需对张弦梁张拉过程中的平面外稳定性问题予以研究。采用几何非线性有限元方法,对张弦梁张拉过程的平面外稳定问题进行弹性屈曲分析,研究了张弦梁主要几何参数对失稳临界索力的影响,提出了确保张拉过程平面外稳定的措施。此外,针对张弦梁单步张拉和分级张拉2种常见施工方法,通过算例比较了两种方法的优缺点。
As a self-balancing system, the beam string structure has been widely used in long-span roof structures. Under the design state, the chord member of the chord beam is restrained by the roof structure such as purlins and supports, and the out-of-plane stability problem is not significant. However, in the process of pre-tensioning the plane beam, prestressing is usually required. Therefore, it is necessary to study the out-of-plane stability during the tensioning of the beam. The nonlinear buckling analysis on the out-of-plane stability of the tensioned beam during tensioning process was conducted by using the geometric nonlinear finite element method. The influence of the main geometric parameters of the beam on the critical instability was studied. The measures to ensure the out-of-plane stability of the tensioning process were proposed. In addition, two common construction methods for single-tensioned and tensioned tensioned stringers are compared, and the advantages and disadvantages of the two methods are compared by examples.