Research on Influence Coefficient and Displacement Amplification Factor of High-Strength Steel Composite Y-Type Eccentrically Braced Structures

The high-strength steel composite Y-type eccentrically braced structure is a new type structure. Ordinary steel (f_y≤345 MPa) is utilized in links to ensure the structure has good plastic deformation capacity under strong earthquake, and high-strength steel (f_y≥460 MPa) is used in frame beams and columns to reduce the cross-sectional size while ensuring the elastic stress state of non-energy consuming components. The new structure has good ductility and energy-dissipating capacity. The structural influence coefficient R is a crucial part of the performance-based seismic design method. If a reasonable value of R is used, the seismic design of structure will be safer, more reasonable, and more economical. It is obviously not reasonable to hide the concept of the structural influence coefficient and adopt a fixed value for all structural systems in the 2016 edition of China’s Code for Seismic Design of Buildings (GB 50011—2010). The research can not only improve the structural performance design method, but also provide a reference for the future design of the structure. The static elastic-plastic analysis (Pushover analysis) and incremental dynamic analysis (IDA analysis) were carried out on 12 finite element models of high-strength steel composite Y-type eccentrically braced frames, and the data obtained by IDA analysis were fitted to reach the IDA performance curve of the structure. The R, C_d, R_μ and R_Ω of each prototype structure were calculated by the capability spectrum method, the effects of the number of structural story N and the length of link e on performance coefficients were analyzed. Comparing the results of Pushover analysis and IDA analysis, the proposed values of each performance coefficient were proposed to provide a reference for the performance design of the new structural systems in the future.