天津光年城-城市展馆单侧大悬挑圆环结构设计

Design of unilateral large cantilever ring structure for city pavilion of Tianjin Lightyear City

天津光年城-城市展馆项目三层展廊为直径50m的圆环,竖向构件均偏置在北侧,圆环整体悬挑长度达38.3m;考虑三层展廊外侧通透的建筑效果,外侧立面无法布置结构构件,主受力构件仅能布置在圆环内侧。该圆环结构存在结构单侧悬挑长度大、竖向支承少、悬挑构件抗扭刚度小、二次悬挑等特点。针对上述结构特点,采取以下设计措施:1)综合考虑结构体系安全性及经济性,悬挑圆环采用空间钢桁架,展廊人行区域为钢桁架上二次悬挑钢梁;2)三层展廊整体荷载通过偏置的楼电梯核心筒传至基础底板,楼电梯核心筒为钢板组合剪力墙结构;3)合理布置基础,减少桩基受拉;4)明确关键构件,提出有针对性的结构抗震性能目标和抗震措施;5)采用多种有限元软件分析对比,保证整体和节点计算结果的可靠性;6)以竖向振动峰值加速度作为大悬挑结构的舒适度控制指标,并设置TMD以满足舒适度要求。分析结果表明,结构满足规范及抗震性能目标要求。

The third floor gallery of city pavilion of Tianjin Lightyear City is a ring with the diameter of 50m,and the vertical member is only on the north side.The overall cantilever length of the ring is 38.3m.Considering the transparent architectural effect of the three-story gallery,the structural members can not be arranged on the outer facade,and the main force bearing members can only be arranged on the inner side of the ring.The ring structure has the characteristics of large single cantilever length,less vertical support,small torsional stiffness of cantilever members,secondary cantilever and so on.In view of the above structural characteristics,the following design measures were taken:1)Considering the safety and economy of the structure system,the space steel truss was used for the cantilever ring,and the secondary cantilever steel beam was used for the pedestrian area of the gallery;2)The whole load of the three-story gallery was transferred to the foundation through the offset core tubes,which is the steel plate composite shear wall structure;3)The foundation was arranged reasonably to reduce the tension of pile foundation;4)The key members were defined,and the targeted seismic performance objectives and measures were proposed;5)A variety of finite element software was used to analyze and compare to ensure the reliability of the overall and node calculation results;6)The vertical vibration members peak acceleration was taken as the comfort control index of large cantilever structure,and TMD was set to meet the comfort requirements.The results show that the structure meets the requirements of the code and seismic performance objective.