常州市体育馆椭圆抛物面弦支穹顶稳定性研究

常州市体育馆椭圆抛物面钢屋盖采用由Levy索杆系和单层网壳构成的弦支穹顶结构,与已研究的常规弦支穹顶相比,其具有体量大,矢跨比高和外形为椭圆抛物面的特点。将弦支穹顶与单层网壳进行稳定性对比研究,包括构件屈曲、线性屈曲和几何非线性屈曲等,分析了高矢跨比弦支穹顶中索杆系的作用以及对结构设计起控制作用的破坏形式。研究结果表明,索杆系增加了弦支穹顶的整体性,降低了其对初始几何缺陷的敏感性,但对结构刚度、基本自振周期和模态、构件屈曲荷载、线性屈曲荷载、无初始缺陷的非线性屈曲荷载、屈曲模态等影响不大。高矢跨比弦支穹顶仍对初始缺陷较为敏感,稳定性仍是结构设计控制因素之一。此外,由于椭圆抛物面外形,活荷载布置形式对结构屈曲模态影响较大,且满跨活荷载并不一定是最不利的活荷载布置形式。

Stability research on elliptic paraboloid suspen-dome of Changzhou Municipal Gymnasium

The steel roof of the Changzhou Municipal Gymnasium is a suspen-dome structure,which consists of levy cable-strut system and single-layer reticulated shell.Compared with conventional suspend-domes,this suspend-dome with an elliptic paraboloid has a greater span(120m) and a rise-span ratio(1/3.7).Through member buckling analysis,linear and geometric nonlinear buckling analysis,comparative studies on stability of suspend-dome and single-layer shell were conducted to understand the influence of cable-strut system on the stability of the suspend-dome of high rise-span ratio,which was the key failure mode.Cable-strut system enhances the structural integrity,decreases the sensitivity to initial geometric defect,but influences little on structural stiffness,fundamental natural period and mode,member buckling load,linear buckling load,geometric nonlinear buckling load without initial geometric defect and buckling modes.The suspen-dome of high rise-span ratio is still sensitive to initial geometric defect and the stability is still one of design control factors.Because the use of the elliptic paraboloid surface,the distribution patterns of live load influences greatly on buckling modes of the structure,and the uniform live load with full span is not always the most dangerous.