Damage Assessment for Performance-Based Design of Rectangular Concrete-Filled Steel Tubes

This paper summarizes research in which the damage evolution of rectangular concrete-filled steel tube (RCFT) members, connections, and frames, was documented using results from experimental tests from around the world. Two types of damage indices were then defined and used for each type of RCFT component to quantify damage. Based on the quantified values of damage, each local damage level identified for the RCFT members was mapped onto appropriate performance levels including Immediate Occupancy, Life Safety, Near Collapse, and Collapse Prevention, to identify how this information may be used in the context of a performance-based design methodology. The experimental data recorded in the database was also used in developing an analysis model to simulate RCFT beam-columns for use in assessing seismic demand and capacity in RCFT structures. A mixed fiber-based finite element formulation was developed allowing geometrically and materially nonlinear analysis RCFTs and good correlation with the experiments was attained.