SEISMIC BEHAVIOR OF SQUARE HIGH-STRENGTH CONCRETE COLUMNS

Results of a study investigating flexural capacity and ductility of square high-strength concrete columns are presented. As part of the investigation, nine 2/3 scale test columns were subjected to constant axial load and cyclic lateral loads. It is concluded that high-strength concrete columns subjected to axial load levels below 20 percent of their axial load capacity and designed based on the seismic provisions of ACI 318-89 have sufficient ductility. However, the ACI 318-89 code provision overestimates flexural capacity of high-strength concrete columns subjected to both axial and bending moment, even columns with confining steel, as required by seismic provisions of the code. Modifications to be incorporated into ACI 318 to calculate conservatively the flexural capacity of high-strength concrete columns are suggested