Seismic Performance Analysis of High-Strength Steel Frames with Y-Shaped Eccentrically Braces

In the high-strength steel frame with Y-shaped eccentrically braces, the energy-consuming beam, which called links, are arranged vertically, and the frame beams are two independent members, so the cross-sectional design is more flexible, and the plastic deformation has less impact on the frame beams and floor slabs, which is easy to repair after the earthquake. The energy-consuming beam sections were designed as ordinary steel with a yield point below 345 MPa to ensure good ductility and energy consumption of the overall structure, while the non-energy-consuming members such as frame beams and columns were designed as high-strength steels, such as Q460 or Q690, to reduce the cross-sectional size of the members ensuring the elastic stress state of the non-energy-consuming members. The length of the links and the number of storeys (height of the structure) were the main factors affecting the performance of the structure. Three sets of prototype structures of high-strength steel frames with Y-shaped eccentric braces with 8, 12 and 16 storeys were designed by the performance-based design method, with each set of link length varying from 700 mm, 900 mm and 1 100 mm, for a total of nine models. The effects of the length of the links and the number of storeys on the failure mode, stiffness, distribution of storey drift and link rotation were investigated by Pushover analysis and dynamic elastoplastic analysis. The results showed that the longer the links, the weaker the lateral stiffness of the structures; the storey drift and the link rotation showed similar distribution patterns for all structures.