Review of seismic performance and design methods for steel concentrically braced frames

Abstract:

This paper presents a state-of-the-art review on recent researches of seismic performance of steel concentrically braced frames and the seismic design methods in codes of practice of China and other countries, aiming at facilitating a safer and more cost-effective design and application of steel concentrically braced frames with single lateral resistant system. Limitations in current Chinese codes are discussed. It is pointed out that the low cycle fatigue performance of braces and their connections is not fully considered for steel concentrically braced frames, and there is no difference between the seismic design methods for structures with high ductility and low ductility. The contributions of semi-rigid connection of beam-column joints, vertical continuity of columns, and semi-rigid connection of column base bolts on the reserved capacities of steel concentrically braced frames with low ductility are neglected. To address these problems, following suggestions have been put forward. It is necessary to further investigate the low cycle fatigue life of braces and their connections and establish the seismic design principle to better match the low cycle fatigue life of braces and their connections. The capacity curve and low cycle fatigue damage of steel concentrically braced frames with high ductility should be analyzed to understand the laws of reduction level of seismic force and the demand of low cycle fatigue cumulative hysteresis energy. By combining force-based and energy-based design, a more reasonable seismic calculation method can be proposed. Structural reserved capacities for seismic resistance should be quantified to construct seismic design methods for steel concentrically braced frames with low ductility, so as to extend its application.