wall tube causes hysteretic energy dissipation by the friction joints slipping a结构华布置图 )连接节点构 Fig5 Friction joints in RC tube in tube structure This kind of structure system can improve the seismic performance in two aspects.Firstly,the deformation modes of frame tube and wall tube are different under lateral loads.The deformation of frame tube is bending type and that of the wall tube is shearing type.The friction joints will do work caused by the different deformation of these two parts.Secondly,under severe earthquake,especially when the seismic predominant period is closed to the natural period of structure,resonance 时 4.2 Energy dissipation structure system with high-level transfer floor With the rapid development of high rise buildings in recent years,in order to meet the functional requirements,the lower part of many high rise buildings is always frame structure so that it can provide large pace for commercial purpose,and the upper part is often used as residence or hotels which need relatively small space Complex structural forms of high rise structure with high-level transfer floor are transfer floor.The internal force and deformation of components on different sides of the transfer floor can also change suddenly which is dangerous in severe earthquakes. To solve these problems.experts propose to apply energy dissipation devices in the structures with high-level transfer floor.In this new structure system,damping devices like dampers or braces are installed in the lower part to the high-level transfer floor and replace some of the shear walls (fig 6).These devices can act as subsidiary components nder normal circumstances.Under severe earthquake,they will provide hrd change hemrmeto Energy dissipation devices can also be installed in the transfer floor thus won't the functional requirements of architecture6 wall tube causes hysteretic energy dissipation by the friction joints slipping [8]. Fig.5 Friction joints in RC tube in tube structure This kind of structure system can improve the seismic performance in two aspects. Firstly, the deformation modes of frame tube and wall tube are different under lateral loads. The deformation of frame tube is bending type and that of the wall tube is shearing type. The friction joints will do work caused by the different deformation of these two parts. Secondly, under severe earthquake, especially when the seismic predominant period is closed to the natural period of structure, resonance can be easy to happen in the structure. The friction joints can help to change the overall stiffness of structure and the natural period, which can avoid the resonance [9]. 4.2 Energy dissipation structure system with high-level transfer floor With the rapid development of high rise buildings in recent years，in order to meet the functional requirements，the lower part of many high rise buildings is always frame structure so that it can provide large space for commercial purpose，and the upper part is often used as residence or hotels which need relatively small space. Complex structural forms of high rise structure with high-level transfer floor are proposed and widely used in China. But a significant problem is that the vertical stiffness is not continuous that may causes damage concentrated in the parts near the transfer floor. The internal force and deformation of components on different sides of the transfer floor can also change suddenly which is dangerous in severe earthquakes. To solve these problems, experts propose to apply energy dissipation devices in the structures with high-level transfer floor. In this new structure system, damping devices like dampers or braces are installed in the lower part to the high-level transfer floor and replace some of the shear walls (Fig.6). These devices can act as subsidiary components under normal circumstances. Under severe earthquake, they will provide additional stiffness and damp to the structure and change the dynamic response to reduce damage to the main structure [10]. Energy dissipation devices can also be installed in the transfer floor thus won’t influence the functional requirements of architecture