（上海建筑设计研究院有限公司， 上海 200041）
［摘要］上海南汇区机关办公中心工程中的巨型空腹桁架结构采用了基于性能的抗震设计，三水准设防的设计为结构抗震性能提供了可靠的保障，即小震和中震下结构保持弹性，大震下主要构件保持弹性。巨型空腹桁架T形抗弯内加劲节点的有限元分析和试验研究表明：内加劲方式可以显著减少节点区的高应力区、保持节点区的弹性性能，同时可达到强节点、弱构件的要求。试验显示该类型节点的破坏模式为腹杆根部受拉翼缘与弦杆连接焊缝开裂、节点域剪切变形和腹杆受压翼缘局部屈曲，节点极限承载力是无加劲节点的2.69倍、设计承载力的3.5倍和腹杆全塑性弯矩的1.44倍，节点具有足够的安全度。工程的研究方法、结论和加劲板的构造建议，为加劲节点的应用提供了参考价值。
［关键词］巨型空腹桁架；基于性能的抗震设计；内加劲节点；节点试验
Vierendeel megatrusses design on earthquake-resistance and inner-stiffened joints
Cao Guofeng, Gu Sichun, Zhang Zhe, Yao Nianliang(Shanghai Institute of Architectural Design & Research Co., Ltd., Shanghai 200041, China)
Abstract:The theory of performance-based seismic design was applied to the vierendeel megatrusses of Shanghai′s Nanhui Administration Center. Three-stage seismic fortification design ensures the safety and seismic performance of the megatrusses. Structural members and joints keep elastic state under multi-encountered and fortification intensity earthquakes, important members and joints hold elasticity under severe earthquakes. The FEA and test study of T-shaped inner-stiffened RHS joints show that the inner-stiffeners can remarkably reduce stress concentration in joint region and hold elastic state, and it satisfies the need for strong joint and weak member. The tests show that the failure modes of this kind of joints include weld split at the foot of the tensioned flange of brace, shear deformation of joint area and local buckling at the compressed flange of brace. Ultimate strength of the joints on the tests is 2.69 times that of unstiffened joints, 3.5 times design strength and 1.44 times plastic bending moment of the brace. This mode of stiffened joints ensures adequate safety. The research methods, conclusions and construction details are developed for the stiffened joints.
Keywords:vierendeel megatrusses;  performance-based seismic design; inner-stiffened RHS joints; joint test
作者简介：曹国峰，副主任工程师，Email:caogf@siadr.com.cn。
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