Low-Cycle Fatigue Test of Circular Concrete Filled Tubular Columns

During earthquake, the inelastic action in the plastic hinge regions of structures and bridges results in significant reversed deformation and failure of the critical components because of cumulative damage. To simulate seismic behavior of structure members and develop a simplicity damage criterion for circular concrete filled steel tubular (CFT) columns subjected to a series of earthquake excitations, an experimental study was undertaken to investigate the cumulative damage and relationship between low cycle fatigue life and displacement amplitude. Two types of large scale circular CFT columns with different kinds of seam weld and inner concrete compressive strength including nine specimens were tested under quasi static loading with constant and variable cyclic amplitudes. The test data were evaluated with the fatigue model relating deformation and fatigue life. Fatigue life expressions for application in damage-based seismic design are developed.