上海世博会中国馆结构弹塑性时程分析

上海世博会中国馆东方之冠建筑造型和结构体系独特,结构为复杂大跨大悬挑钢-混凝土混合结构,主体结构为四个混凝土筒体,上部楼屋面采用混凝土梁板体系、型钢梁-混凝土板梁板体系和钢桁架梁-混凝土板梁板体系。由于上部结构悬挑较大,结构1阶振型为扭转振型,不满足现行建筑抗震设计规范的要求。采用NosaCAD2005有限元程序建立整体结构分析模型,压弯构件采用纤维截面模型,墙体采用非线性平板壳单元,以反映构件非线性复杂受力情况。通过7度多遇和7度罕遇烈度下的弹塑性时程分析,研究了该结构的变形、内力、破坏情况的发展历程。计算结果表明,小震情况下,结构构件未出现损坏;大震情况下,结构最大层间位移角满足1/100的限值要求,筒体构件损坏顺序和分布较为合理,能在一定程度上耗散地震输入能量。出现塑性铰的杆件未超过极限承载能力,结构可以满足"小震不坏"、"大震不倒"的抗震设防要求。最后根据构件的受力或损坏情况,给出了设计改进建议。

Elasto-plastic time history analysis of the structure of China Pavilion at the 2010 World EXPO

The peculiar building style and special structural system of China Pavilion at EXPO 2010 Shanghai China is a long span and large cantilevered steel-concrete hybrid structure.The main structure is composed of four concrete tubes.The concrete beam and slab,steel beam and concrete slab,and steel truss and concrete slab floor system,are adopted for upper part floors and roof.Due to large cantilevered upper part,the first free vibration mode is torsion mode,which does not meet the requirement of design code.Using NosaCAD2005,the structural analysis model is established.In order to simulate the nonlinear behavior of members under the complex load condition,the fiber section model is chosen for compression-flexure frame members and nonlinear flat shell element is chosen for tube wall.The elasto-plastic time history analysis is carried out to study the seismic behavior of the structure under the frequent and rare intensity of 7 degree-earthquake.Based on the analysis,the deformations,internal forces and damage patterns of the structure are investigated.Under the frequent earthquakes,there is no damaged element.Under the rare earthquakes the maximum inter story drifts are less than the seismic design requirement of Chinese code.The order and distribution of damages on components of the tubes are reasonable,which can dissipate some dynamic energy.Yielding hinges occur on some elements,however,which do not reach the ultimate load carrying capacity of structural components.The structure can meet the code requirements of no damage under frequent earthquake and without collapse under rare earthquake.Finally,according to internal forces and load-carrying capacity or damage state of element,suggestion for improving the seismic design is given.