上海中心大厦伸臂桁架与巨柱和核心筒连接的静力性能试验研究

超高层框架-核心筒结构体系中，伸臂桁架连接着外围巨柱框架与内部核心筒，需传递巨大内力，其连接构造、传力机制等非常复杂。以上海中心大厦工程为背景，选取钢骨混凝土巨柱-伸臂桁架-环带桁架连接区域和伸臂桁架-核心筒连接区域进行了单调静力加载试验，并进行了有限元分析和简化模型计算分析。结果表明：伸臂桁架能够有效连接相邻构件并可靠传力，其破坏模式表现为伸臂桁架斜腹杆的受压屈曲以及上、下弦杆的弯曲变形，具有较好的延性；伸臂桁架与巨柱和核心筒连接的节点板虽然部分区域进入塑性，但塑性变形不明显，表明连接区域的承载力远高于杆件的承载力；有限元分析及简化模型分析结果与试验结果吻合良好；简化模型反映了伸臂桁架的非线性受力机理，可对其失效荷载进行准确预测，并可根据结构性能设计要求进行伸臂桁架分析和构件截面选择。

Monotonic static tests on outrigger truss and its connection with mega column and core tube of the Shanghai Tower

Outrigger truss which connects external columns and the core tube in super high-rise frame-core tube structures plays a key role in transferring huge loads, and its construction details as well as load-carrying mechanism are also complex. To support the performance-based design of the Shanghai Tower, the highest building under construction in China, static tests and numerical simulation were conducted on two typical specimens: SRC mega column-outrigger truss-belt truss composite joints and outrigger truss-core tube composite joints. The results indicate that outrigger truss can effectively connect the core tube and the mega columns and transmit loads; the failure mode exhibit the buckling of the web member and the bending-hinge development at the upper and lower chords in the outrigger truss, implying excellent ductility of the specimen. Meanwhile, the gusset plates connecting the outrigger truss and the core develop only small plastic strain, indicating its bearing capacity is much higher than the members connected. FEM model and simplified mechanical model were both generated and analyzed with the results showing good agreements with those of tests. The simplified model reveals the mechanism of non-linear behavior of the outrigger truss, and predicts its ultimate capacity and stiffness with good accuracy. The model is proved to be capable of providing a sufficient tool for conceptual design of structures with outrigger truss.