Anti-seismic Analysis Of Storey-adding Structure With Eccentric Buckling-restrained Brace

The buckling-restrained brace can make up the deficiency of the traditional steel support, and can be maintained under the action of earthquake, which can keep the "yield but not buckling", provide to the main structure of the larger stiffness, and the plastic deformation of the core material can be dissipated. The shear plastic deformation of the beam section under the influence of large earthquakes can produce good deformation capacity and energy dissipation capacity. In this paper, the assumption that the two are combined to form a eccentric buckling-restrained brace, the buckling restrained brace and an energy dissipation beam segment can be dissipated under the action of large earthquakes.Through the comparative analysis of the storey-adding structure without brace,the ordinary eccentric steel brace storey-adding structure,the center buckling-restrained brace storey-adding structure and the eccentric buckling-restrained brace storey-adding structure on the multi and rare earthquake,we can see:under the action of the multi earthquake, the whole system is in the elastic deformation stage,the buckling-restrained brace and the energy dissipation section have not yet produced plastic deformation, which can not be dissipated.The buckling restrained brace and the eccentric support energy dissipation beam segment into plastic deformation stage under the rare earthquake,the two joint energy dissipation to protect the main structure is not damaged.The combined effect of the two is obviously superior to the single shock absorption effect.Especially in the connection of old and new structures,seismic response parameter of the eccentric buckling-restrained brace storey-adding structure change more slowly,have no larger stress concentration phenomenon and the whiplash effect,control the generation of the weak layer effectively.The arrangement quantity of the eccentric buckling-restrained brace in the plane is not the more the better.In fact, when the eccentric buckling-restrained brace to reach a certain number,the seismic performance of the storey-adding structure has no obvious improvement or the improvement rate is very small with the increase in number.After analysis,the eccentric buckling-restrained brace can be arranged every two times column space or three times column space,the effect of such arrangement is same as shock absorption effect of filling in each axis.This arrangement not only saves space, but also reduce the cost of investment, to achieve the effect of kill two birds with one stone.The eccentric buckling-restrained brace should be arranged uniformly on the facade,as far as possible don’t put all the buckling restrained brace up to a certain number of layers,it is easy to form the phenomenon of stress concentration and increasing the whipping effect.The best layout of the facade should be staggered layout this can not only ensure that the upper and lower stiffness uniform, control the generation of the weak layer, but also to achieve a good energy dissipation effect.Direct layer system’s rigid joints is more conducive to energy dissipation effect of the eccentric buckling-restrained brace,is more conducive to the seismic performance.So it is suggested to use rigid joints.