基于初始基准态的FAST反射面索网结构性能优化分析研究  

Performance optimization analysis of FAST reflector supported cable-net based on initial baseline state

作　　者：罗斌[1,2] 郭正兴[1,2] 王凯[3] 肖全东[1,2] 

机构地区：[1]东南大学混凝土及预应力混凝土结构教育部重点实验室,江苏南京210096 [2]东南大学国家预应力工程技术研究中心,江苏南京210096 [3]东南大学建筑设计研究院有限公司,江苏南京210018

出　　处：《土木工程学报》2015年第12期12-22,共11页China Civil Engineering Journal

基　　金：国家科技支撑计划课题<建筑结构绿色建造专项技术研究>(2012BAJ03B06)

摘　　要：500m口径射电望远镜FAST反射面索网结构,由短程线型面索网和下拉索构成,采用高强度预应力钢绞线束索,主动变位工作是其最大特点。索网优化设计采用容许应力法,基于索网为形控结构,提出标准球面基准态优化分析方法:根据主动变位工作基本要求和主动变位引起的面索应变变化幅值一定,首先确定下拉索初张力值和面索初应力上、下限值,通过找力分析确定面索初张力后,以初应力接近上限为原则确定面索截面规格。分析若干关键因素对索网结构性能的影响,结果表明:为避免工作态出现过低下拉索力,在面索弹性模量和容许应力一定的条件下,只能通过维持面索初应力水平,增大面索截面积来提高下拉索和面索初张力;周圈钢桁架宜采用滑动支座和较低刚度,并可采取周圈钢桁架沿径向预偏安装、边缘下拉索张拉固定后不参与主动变位的措施;钢索安全系数从2.5调低至2.0,可提高容许应力和面索初应力上限、减少材料和改善内力状况。另外,通过对比碳纤维索和钢索的力学特性,高强、低弹模、轻质量、抗疲劳的碳纤维索适合FAST索网结构。FAST （Five-hundred-meter-Aperture Spherical Telescope） reflector supported cable-net structure consists of geodesic surface cable-nets and adjust cables, which are high-strength prestress strand. Active deflection is the most prominent feature of the cable-net structure. As the cable-net structure is shape controlled, the standard spherical baseline state optimization analysis method is proposed with the use of allowable stress method. At first, the initial tension value of adjust cables and stress limit of surface cables are determined by the basic requirements of active deflection work and certain amplitude strain change. Through force-finding analysis, the initial tension value of surface cables are found, surface cable sectional specifications are determined with the principle that initial stress is close to the upper limit. Effect analysis of several key factors on performance of the cable-net structure are conducted. To avoid low tension value of adjust cables at work state, the initial tension value of cables can only be increased by maintaining surface cable stress level and increasing the surface cable sectional specification under certain elastic modulus and allowable stress. Sliding bearing and low stiffness will be appropriate for circumferential steel truss, which may be partially installed along the radial direction. And also, the edge adjust cable will not be involved in active deflection after tension. The allowable stress and initial stress upper limit will be improved since cable safety coefficient reduced from 2.5 to 2.0, which can also reduce material amount and improve the internal force. In addition, through the comparison of mechanical properties of carbon fiber cable and steel cable, carbon fiber cable with high strength, low elastic modulus, light weight and fatigue resistance is suitable for FAST cable-net structure.

关 键 词：FAST 索网 初始基准态 结构性能 优化分析 

分 类 号：TU311[建筑科学—结构工程]