Study on Structural Design of Grid Shell Composed of Thin Round Timber and Tension Member

在本研究中，由薄圆木和张拉杆组成的预制木桁架系统应用于网格壳和张拉整体结构。重点研究了该系统的性能，获得了由该系统组成的网格壳的基本结构设计数据。首先，对球面单层三向网格穹顶进行了加载试验。其次，对双向网格中张力构件对角线的单层双向网格穹顶进行了处理，重点考虑了张力构件的影响和构件长度的精度。验证了拉杆构件初始轴向力对穹顶屈曲行为的影响。实验和分析结果表明了该系统对单层穹顶结构的适用性。然后，通过网格构件轴向刚度比与受拉构件轴向刚度比的关系，定量评价了构件轴向力与规定值的比值；并将该系统应用于由张拉整体结构体系组成的网壳结构。采用带加劲杆构件的4杆张拉整体模型作为结构单元。梁状结构、拱状结构、圆柱状结构均由该结构单元构成。通过装配试验对构件长度、初始形式、自平衡力和施工过程进行了检验。这些结构的结构性能也通过加载试验进行了检验。装配试验结果表明，该装置具有较高的装配效率、初始形状和自平衡应力精度。加载试验表明，该系统在考虑部分构件松动的情况下具有稳定的荷载变形行为，对张拉整体结构具有一定的适用性。

In this study, the prefabricated wooden truss system composed of the thin round timber and tension rods was applied to grid shells and tensegrity structures. We focus the performance of the system and obtain the basic structural design data for grid shells composed of this system.Firstly, a single layer three way grid dome with spherical surface was treated by loading experiments. Next, a single layer two way grid dome with diagonals of tension members in two way grid was treated focusing on both effect of tension members and accuracy of member length. The effect of the initial axial forces of tension rod member on the buckling behaviour of the dome was confirmed. The applicability of this system to the single layer dome was shown by the experimental and analytical results. Then, the ratio of introducing axial force to the specified value in constituent member was evaluated quantitatively by the relation between the axial rigidity ratio of a grid member and that of tension member.Furthermore, this system is applied to the grid shells composed of tensegrity structural system. The 4 strut model tensegrity with stiffening rod member is used as a structural unit. The beamlike structure, arch-like structure, and cylindrical structures are made of this structural unit. The member length, the initial form, self equilibrium forces and the construction process are examined by the assembly experiment. The structural behaviour of these structures is also examined by the loading experiment. The efficiency of construction process, the high accuracy of initial form and self equilibrium stress were shown by the assembly experiments. The load deformation behavior was stable with respect to slacking of some members and the applicability of this system to tensegrity structures was shown by the loading experiment.