目的:常规索穹顶结构具有受预应力影响较大、不易于铺设刚性屋面等缺陷,且施工过程中存在变形较大及拉索松垂等问题,施工模拟难度较大。本文探讨一种新型索穹顶结构的构件性能和受力特点,研究结构施工过程分析的可行性及最优布置形式。创新点:1.提出一种易于铺设刚性屋面的新型拉梁式索穹顶结构;2.提出一种累积牵引提升施工技术;3.通过非线性动力有限元找形分析方法(NDFEM)实现施工模拟过程。方法:1.通过试验分析,证明NDFEM法可以实现拉梁式索穹项的施工过程模拟(图1t-13和表4);2.通过理论推导,对比两铰拉梁、三铰拉梁以及悬索单元在跨中集中荷载和均布荷载作用下的变形和受力特点(公式9-17);3.通过数值模拟分析,运用累积牵引提升施工方法(图4)在施工过程分析中对机构铰的布置形式进行可行性研究,并提出最优分布模式。结论:1.不同于常规索穹顶结构只受拉力的脊索,拉梁可以同时承受拉力与弯矩,并且弯曲应力较小,不易失稳;2.整体牵引提升可以很好地完成拉梁式索穹项结构的施工成型过程:在此过程中应设置合理的机构铰将拉梁网格转化为机构:3.NDFEM找形分析方法能够有效跟踪分析施工全过程,分析精度较高;4.仅在中拉梁或内拉梁上布置机构铰可以在保证结构性能的同时最大限度地减少后期施工的工作量,为最优铰节点分布模式。
A cable dome is a form of cable-strut tensegrity structure, which is popular for long span membrane roof structures. However, there is an opportunity for its major development for a wider range of applications if rigid roof cable dome structures can be achieved. In this paper, we propose the tensile beam-cable dome (TBCD), a new type of space structure based on the features of the cable dome. By changing the ridge cables to hinged tensile beams, a structure can easily be covered with a rigid roof. We introduce its configuration and mechanical characteristics, and put forward four categories of this structure with hinges set at different locations on the tensile beams. In addition to achieving the aims of tow-lifting and tensioning construction, the integral tow-lifting method is presented for TBCD, and the nonlinear dynamic finite element method (NDFEM) of form-finding analysis is introduced for the overall construction analysis. For integral tow-lifting construction, the mechanism hinges should be set at the middle of the tensile beams to make the tensile beam grid into a mechanism system. Through construction analysis of seven mechanism hinge distribution modes, the modes with mechanism hinges set only on the middle or inner tensile beams were optimal.