索桁架固定千斤顶斜向牵引整体提升的无支架施工技术及全过程分析

索桁架固定千斤顶斜向牵引整体提升的无支架施工方法，利用固定在上弦锚固节点处的提升千斤顶，通过斜向牵引上弦索来整体提升在地面低空组装的索杆系，最后通过张拉下弦索使结构成型。该方法高空作业少，节省搭设支架的费用和工期，实现工装轻型化，提高施工效率。乐清体育场挑篷为月牙形非封闭索桁架结构，采用该方法施工，并采用基于非线性动力有限元的索杆系静力平衡态找形分析方法，进行结构自质量初始态、提升牵引和张拉全过程分析及扰动稳定分析。研究结果表明：结构自质量对弦索索力影响较大，可增大上弦索力和减小下弦索力，但对环索索力影响小；在提升牵引阶段位形变化大，上弦索和环索构成主承力构件，下弦索处于松垂悬挂状态；在下弦索张拉阶段，弦索和环索的索力逐渐增加，结构刚化成型；最外侧上、下弦钢拉杆在施工过程中内力变化剧烈，应验算其承载力；上、下弦交叉的索桁架，压杆容易出现平面外过大位移甚至翻转，此在牵引提升起始时最为不利，可在压杆顶部设置稳定工装索，保证位形几何稳定。

Research on non-bracket inclinded tow-lifting construction technology with fixed jacks and complete process analysis of cable-truss

For cable-truss structure, a new construction method involving non-bracket tow-lifting with fixed jacks is presented. Using this method, cables and struts are first assembled at low altitude. Then, upper-chord cables and other cable-struts are towed by tool cables and jacks, which are connected with upper-chord anchor joints through pylons, until the upper-chord cables are connected with outer compressive ring. Finally, the lower-chord cables are simultaneously tensioned to form. This method has a few operations at high altitude, saves cost and time of installing brackets, makes tensioning equipment lighter and improves the construction efficiency. This method has been applied to crescent unclosed cable-truss structure of Yueqing stadium, and initial state with self-weight, lift-towing and tension process, as well as disturbance stability were analyzed with method of static equilibrium form-finding analysis based on nonlinear dynamic FEM. The results indicate that tensioning of radial cables is affected remarkably by self-weight, which causes increase of upper radial cables tension and decrease of lower radial cables tension. Self-weight has little effect on ring cables. At the stage of tow-lifting, the configurations are changed significantly. The upper radial cables and ring cables mainly support the cable-truss. The lower radial cables are overhanging. At the stage of tensioning lower radial cables, the radial cable force is increased gradually, and at last, the entire structure is rigidized and formed. During construction process, the force of the outermost upper and lower radial steel bars changes acutely, so bearing capacity should be checked. Overlarge displacement and even overturn appear on struts easily, which are located at the crossed place of the upper and lower radial cables. For the stability of configurations, tooling cables may be installed on the top of struts.