Structural design and research of the towers of Shanghai Lujiazui X2 area

The south and north towers of Shanghai Lujiazui X2 area are 250m and 260m high separately,with mega-frame core-tube as the main structural system.In this paper,the structural system is introduced from several aspects: the importance of the core,the settlement of outrigger truss and the layout of beam-slab system.Considering the conditions of outrigger truss,the shear and moment distribution between the core-tube and frame under earthquake are compared,and it is indicated that if structural stiffness is reasontable,the outrigger truss can balance the load on the core-tube and frame,without excessively abrupt change in structure stiffness.Nonlinear static pushover analysis shows the development of the plastic-hinges,which indicates that the anti-seismic defense lines can work in cooperation effectively.The result of shaking table test shows that the structure meets current code requirements(seismic intensity of 7 degree).Some local damages appear under seismic intensity of 8 degree,to which some suggestions are given.The research demonstrates that the two towers have reasonable structural system and good seismic behaviors.