Abstract
This paper presents a ratio of strength deterioration of R/C columns using high strength concrete up to 160MPa and high strength steel due to cyclic loading of the same drift angle. The ratio of strength deterioration was defined as second cycle strength over first cycle strength. The ratio was decreased as a displacement increased from maximun strength point to limit displacement point and a large correlation was found between the ratios at these two points and the limit displacement of R/C columns. Based on 36 test data, the estimate equations for the ratio at an optional displacement was proposed. The equations showed good agreement with the test data.
