月牙形索桁罩棚结构的静力性能模型试验

Model experiment on the static behaviors of a crescent-shaped cable-truss canopy structure

以浙江省乐清市体育场工程为背景,对一种新型的月牙形索桁结构进行1∶15缩尺模型的静力性能试验研究.分析试验模型和实际结构物理参数的相似比例关系,数值验证缩尺后试验模型内力和位移相似比的符合性.介绍模型试验主要节点构造做法、索力和变形的测量方法、张拉和加载方法.采用控制上下径向索索力的方法对结构张拉成形,并考察月牙形索桁结构的初始态预张力分布特点.进行自重、恒载、半跨活载及全跨活载4种工况下的加载试验,并测量径向索和环索内力以及环索节点位移.试验结果表明,控制上下径向索索力的张拉方法能够有效建立结构的设计预张力,环索实测内力偏差与理论值相比可控制在3.3%以内.在4种加载工况下,月牙形索桁结构试验模型的内力和变形值与设计值符合良好,说明在设计预张力下实际结构具有可靠的刚度和承载力.

A 1/15 scale model was employed to investigate the static behaviors of a novel crescent-shaped cable-truss tensile system used as a canopy structure in Yueqing stadium, Zhejiang Province. The similarity ratios of some physical parameters between experiment model and practical structure were analyzed. The coincidence of similarity ratios is numerically verified by checking the internal forces and displacements of the scaled model. Some typical joint details of the experiment model, measurement methods of cable tension and nodal displacement, as well as cable prestretching and load applying methods were introduced. The properties of pretension distribution in initial configuration were investigated for the model structure after erection by stretching the upper and lower radial cables and also controlling their tension forces. Loading tests were further carried out for four load cases, including self-weight, dead load, half-span live load and whole-span live load. The corresponding internal forces of radial cables and ring cables, joint displacements of ring cables were measured. The testing results reveal that the structural design pretension can be established effectively by the method of controlling the tension forces of the upper and lower radial cables. The relative deviation of measured tension forces of ring cables can be controlledwithin 3.3 ~ compared with the theoretical values. The responses of internal force and displacement of this crescent-shaped cable-truss structural model under four load cases also have well coincidence with the design values, and reflect the reliability of practical structure in stiffness and load-bearing capacity under the design pretension.