广州秀场屋盖钢结构分析与设计

Structural Analysis and Design of Guangzhou Show Theatre Roof

广州秀场位于广州市花都区,为特定主题演出秀场,总建筑面积为5.02万m^(2)。内部主体结构采用框架-核心筒结构;钢屋盖为自由曲面的单层网格结构,其投影直径约为105 m,竖向高度约为29.1 m。为适应幕墙需求钢屋盖结构划分成边长为3 m左右的四边形和三角形网格;全部网格数为4000个左右。由于屋盖杆件和节点数量多,若全部杆件作为主受力构件,会使得结构传力路径复杂、施工难度增加。为确定更优的结构方案,对比分析了非主次网格和主次网格两种方案;为更高效地布置混凝土楼板和钢屋面的连接节点,对不同边界情况进行了对比分析;为确定钢屋盖与下部混凝土支承结构受力的相互作用影响大小,对合体模型和独立模型进行了对比计算分析;并进一步对整体结构进行了动力分析和静力分析,确保结构的振型、周期以及变形均在合理范围。采用屈曲分析计算杆件的临界荷载并反算其计算长度,从而较精确地对其强度进行验算。结果表明:1)因主次网格方案有受力性能好、材料用量少和施工难度较小等优点,故确定采用主次网格方案。2)主网格、次网格和屋面支撑杆件的最大应力比分别为0.78、0.85和0.72。3)采用ANSYS对结构进行了考虑材料和几何双非线性的整体稳定分析,根据荷载位移曲线可知:荷载加至荷载标准值1.8倍以前,结构基本处于线弹性状态;结构的极限荷载约为荷载标准值的4.6倍,满足JGJ 7—2010《空间网格结构技术规程》中的极限承载力系数K>2的要求。最后针对计算采用的边界假定,对主要连接节点进行了专门设计,保证节点构造满足边界假定要求。4)确定仅F1、F3和F5层混凝土楼板与钢屋盖进行铰接连接。5)合体模型和独立模型在静力荷载作用下的变形和动力特性均存在一定差异,故计算钢屋盖时需采用合体模型进行计算。

Guangzhou Show Theatre is located in Huadu District of Guangzhou, which is a specific theme Theatre with a total building area of about 50 200 m^(2). The main structure adopted the frame core tube structure system, and the steel roof adopted single layer grid structure of free surface, with diameter of 105 m and height of 29.1 m. In order to meet the needs of the curtain, the steel roof structure was meshed into approximately 4 000 grids of triangle and quadrilateral with 3 m length of side. It will make the load-transfered path unclear and increase construction difficulty when all numbers were designed to main forced components. The primary-secondary and the primary grid scheme were analyzed comparatively in order to select the better structure scheme. Comparative analysis of different boundaries models were carried out in order to confirm the most efficient boundary conditions. The whole model and independent model were analyzed comparatively in order to defining the scale of influence between the steel roof and the concrete structure. The static analysis and dynamic analysis was carried out in order to ensure mode, period of vibration and deformation was in a reasonable range. Buckling analysis was used to calculate the critical force and back calculate the calculation length of the element, so as to accurately check the strength of the element. The following conclusions can be drawn from the result of analysis. 1) The primary-secondary grid structure scheme was adopted by comparative analysis, which not only had better mechanical performance, but also could reduce material consumption and construction difficulty. 2) The checking calculation results showed that maximum stress ratio of main member, secondary member and roof bracing member was respectively 0.78,0.85 and 0.72. 3) The overall stability of the structure was analyzed considering material nonlinearity and geometrical nonlinearity by ANSYS.The load-displacement curve showed that the structure was elastic under 1.8 times nominal load and the ultimate load was 4.6 time as the nominal load. Connections were specifically design in order to mechanical property of connections meet the calculation assumptions. 4) Hinged connection joint was set up between the roof members and the first, third and fifth concrete floor. 5) The structure static response analysis and dynamic response existed difference among the whole model and independent model, so the whole model was adopted to calculate the steel roof structure.