某带大悬挑的办公塔楼结构设计

Structural design of an office tower with large cantilever

某办公塔楼采用钢筋混凝土核心筒-大悬挑结构体系,塔楼3层的外围框架柱缺失,导致4~13层核心筒外侧均为悬挑结构,最大悬挑尺寸为19.2m。采用钢筋混凝土核心筒作为竖向抗侧力体系,在4层和9层设置悬臂桁架与环带桁架组成的悬挑转换体系,将上部楼层荷载传递给核心筒。对结构进行了抗震性能化设计,对核心筒关键部位采取了设置钢板、型钢柱、型钢梁等加强措施,大震动力弹塑性时程分析结果表明核心筒具有优良的抗震性能。对悬挑转换体系进行了专项分析,具体包括:核心筒环通钢梁的设计;楼板刚度对悬臂桁架、环带桁架受力和变形的影响规律;对悬挑转换部位楼板进行应力分析,并采取后浇带和铺设钢板的措施;大悬挑关键节点分析等。结果表明,悬挑转换体系具有较高的安全储备。并针对悬挑转换结构的特点,给出了可行的施工方案。

The reinforced concrete core tube-large cantilever structure system was adopted in an office tower, the external frame columns at the 3 rd floor were absent, resulting the 4 th to 13 th floors outside the core tube are cantilevered structure, and the maximum cantilever size was 19.2 m.The reinforced concrete core tube was adopted as the vertical lateral force resistance system, and cantilever truss and belt truss was set at the 4 th and 9 th floor, composed of cantilevered transfer system,transfering the load from the upper floor to the core tube. Performance-based seismic analysis of the structure was studied. Steel plates, steel columns, steel beams and other strengthening measures were adopted at the key parts of the core tube. The results of the dynamic elastic-plastic time-history analysis of the rare earthquake show that core tube has excellent seismic performance. Special analysis was conducted on the cantilevered transfer system, including the design of inner belt steel beam of core tube, the influencing rules of slab stiffness on the stress and deformation of the cantilever truss and belt truss, the stress analysis on key slabs in cantilever part, measures of post cast strip and laying steel plate were taken, key node analysis for large cantilever truss, et al. The above analysis results show that the cantilevered transfer system has a high safety storage to achieve its desired seismic performance goals. According to the characteristics of cantilever conversion structure, the feasible construction scheme is given.