超大跨度机库大门桁架方案优化研究

Study on optimized scheme of the gate truss of long-span hangar

在有限元分析模型得到充分验证的基础上,对北京A380机库大门桁架进行了降高度分析。分析结果表明:大跨度维修机库大门桁架受力最大、最不利杆件集中分布在桁架跨中负弯矩区,此处的设计是机库大门桁架设计的关键;综合采用预应力钢结构和钢与混凝土组合结构技术可以有效地降低A380机库大门桁架高度,但桁架高度降到8m以下时,自重和用钢量将会比原设计方案增加较多,且施工比较困难;A380机库大门桁架高度不小于8m时,降低跨中立柱高度有助于改善大门桁架受力,使跨中支座处下弦杆中混凝土灌注量小,自重轻,弦杆截面过渡平缓。提出了超大跨度机库屋盖大门桁架优化设计方案。

After the finite element analysis model has been validated, the analysis on lowering the gate truss height of A380 hangar in Beijing is carried out. The analysis results show that the most unfavorable members of the long-span hangar gate truss distribute concentratively in the mid-span negative moment region of the truss, where is the key part of the design of the hangar gate truss; the gate truss height of A380 hangar can be lowered effectively by using the prestressed steel structure technology and the steel- concrete composite structure technology synthetically, but when the truss height is below 8m, the deadweight and steel consumption will be more than that of the original design scheme, and the construction is difficult; when the gate truss height of A380 hangar is above 8m, lowering the mid-span column helps to improve the internal force distribution of the gate truss, which causes the concrete in the bottom chord of the gate truss at the mid-span support decreasing, the deadweight of the gate truss lightening and the chord section changing gently. The optimized design scheme of long-span hangars is proposed.