世博文化中心主体结构设计与分析

Design and analysis of main structure of the World Expo Cultural Center

上海世博文化中心碟形主体结构由36榀悬臂长度不等的桁架和内框架结构组成。结构受力以静荷载为主。有效控制桁架端部的变形及减小桁架和内框架的受力是该结构设计的重点。设计时分析了结构的受力特点并针对关键构件进行了加强,首先在内框架顶部设置两道矩形钢管主环梁;其次将六层楼板加厚为200mm,并在楼板应力大的桁架第一节间位置铺设钢板。上述措施如同在36榀内框架顶部加了一道"紧箍",显著减小了桁架端部变形及主要构件的受力。动力分析表明:该结构的振动特性不同于普通的高层建筑,扭转成为第1振型,但结构具有相当大的侧向刚度,且抗侧力构件分布均匀,并采用钢框架结构,在水平地震作用下不致出现脆性破坏。为研究楼板刚度对结构的影响,建立了考虑楼板刚度、不考虑楼板刚度及单榀框架等3个计算模型,分析了主要杆件在这3个计算模型下受力的差异,结果表明,楼板刚度对主要杆件的受力有显著影响,但对不同的杆件受力影响有所不同,设计时须取3个计算模型下的包络结果进行设计。

The main structure of the World Expo Cultural Center consists of 36 cantilever trusses of varying span and inner frames.Static load is the primary load case of such a structure.Effective control of the deformation of the end of truss and reduction of the force of the truss and inner frame are the focus during the structural design.The load bearing feature of the structure was analyzed and the key components was strengthened correspondingly.Firstly,two circumferential frame beams on the top of the column were designed with steel rectangular tube;secondly,slab of the sixth floor was thickened to 200mm and steel plate was welded between the first panel of the cantilever truss.These measures put a ＇tight restriction＇ on the top of 36 cantilever trusses and significantly reduced the deformation of the end of truss and the force of main members.Dynamic analysis shows that the vibration characteristics of the structure are different from normal tall buildings.As for this structure,torsion is the first modal shape,but lateral stiffness of the structure is very strong,lateral force resisting components are evenly distributed and the frame is made of steel so that brittle failure is not easy to occur when the structure suffering horizontal earthquake.In order to study the influence of floor stiffness,three models of calculating real floor stiffness,without floor stiffness and only single frame were respectively analyzed and the differences of the force of main components were studied in details.The results indicate that floor stiffness has a significant influence on the force of main members but the influence is different.So that the envelope results of the above three models are all considered during the design course.