Research on Seismic Performance of Damaged Steel Columns

Abstract

Due to its advantages such as light weight, high strength, good seismic performance, and uniform material properties, steel structures have been widely used in various engineering structures. However, steel structures may suffer damage or even failure during service due to fire, corrosion, earthquakes, ice-snow disasters, wind disasters, or other abnormal service loads. In the 1994 Northridge earthquake in the United States and the 1995 Kobe earthquake in Japan, some steel frame structures still exhibited damage and failure of varying degrees, which prompted people to reconsider the seismic performance of steel structures. Damage can lead to the degradation of the mechanical properties of steel structures. Whether these damaged steel structures can meet normal stress requirements? Is reinforcement necessary? Or should they be demolished and rebuilt? These issues affect the rational disposal decisions for damaged steel structures and are related to people's property safety, which have always been the focus and difficulty in disaster prevention and mitigation work. A large number of studies have shown that damage will cause significant degradation of mechanical properties such as strength, stiffness, and energy dissipation capacity of components and structures, seriously affecting the bearing capacity, stiffness, stability, and seismic performance of steel structures. As the main load-bearing component, the steel column transfers the dead load (self-weight) of the superstructure, live load (service load), and additional loads (such as equipment loads) to the foundation in the form of axial force, bending moment, and shear force, forming a complete load transfer path. In seismic design, steel columns are often designed as ductile energy-dissipating components, which absorb seismic energy through local plastic deformation (such as flange buckling and web shear yielding) to avoid brittle failure of the structure. Through the synergistic effect of the column's own flexural stiffness and the frame joints, they resist the shear force and bending moment generated by horizontal wind loads and seismic actions, maintaining the overall stability of the structure. Under seismic action, once a steel column is damaged, its mechanical properties will degrade, and even cause floor collapse, seriously threatening building safety.