The Design And Calculation Of Eccentrically Braced Frames

There are two systems of conventional tall steel buildings: moment-resisting frames and concentrically braced frames.Moment-resisting frames have good inelastic behavior and are easy in interior planning thanks to being without obstacle between columns. Being with great flexibility, however, it is not economical to meet the inter story drift limit when the building is high.Concentrically braced frames can provide high elastic stiffness and are widely used. But the buckling of the brace can make the capacity drop.Eccentrically braced frames have the advantages of both moment-resisting frames and concentrically braced frames. This system can provide high elastic stiffness and large inelastic energy dissipation capacity in resisting lateral loads caused by seismic activity. They can reduce material consumption, and keep good ductility at extreme overloads. In high seismic regions, eccentrically braced frames are quite popular, they have good ductility and can sustain to severe cyclic loads, and they are used widely in seismic design. "Code for seismic design of building" stipulate, eccentrically braced frames are used in seismic regions No. 8 or above, but they have not yet used up to present time for buildings designed by domestic designers. In this paper, the practical calculations of eccentrically braced frames are discussed with reference to the US examples and codes on basis of the specifications of China. The calculations place emphasis on the internal force of elements, the design of links, the design of beams out side the links, the design of braces, the design of columns and so on, and the example is added. They provide the theoretical bases and practical way for project design, and are helpful to the comprehension of the design procedures for the designers and popularization of this system.