Abstract: To investigate the difference of the mechanical behavior and damage evolution of concrete filled square and circular steel tubular columns(CFSST、CFCST) after high temperature and water spray cooling, 14 concrete filled square steel tubular columns and 14 concrete filled circular steel tubular columns were designed with different parameters as sectional form, high temperature, concrete strength, and cooling methods. The specimens after water spray cooling were tested under uniaxial compression, and the mechanical properties including peak stress, initial rigidity, ductility coefficient and energy dissipation coefficient of CFSST and CFCST were compared and analyzed. Determine the degree of damage of the specimen, compare the relationship between damage and temperature, and the evolution of residual bearing capacity with damage. The results indicated that: The peak stress, ductility, and energy dissipation of CFCST specimens are greater. As the temperature increases, the bearing capacity of CFCST specimens decreases more slowly, but the ductility and the energy dissipation capacity of CFSST specimens increases faster. Relative to CFCST specimens, the cooling method had more significantly influence on the ductility and energy consumption capacity of CFSST specimens. As the temperature increases, the damage of CFSST specimens increases faster, and the residual bearing capacity of CFSST specimens decreases linearly as the increase of the damage.

Key words: high temperature, spray cooling, cross-section form, axial compression properties, damage analysis