EXPERIMENTAL STUDY ON CONFINEMENT EFFECTS OF RECTANGULAR TIES IN REINFORCED CONCRETE COLUMNS

To examine the confinement effects of rectangular ties in reinforced concrete columns, 18 short tied columns are tested. The variables are the tie spacing, the amount and the yield strength of lateral steel, the tie configuration, and the amount and the distribution of longitudinal steel. Based on the test results, the stress-strain curves of confined core concrete are obtained and the results are compared with some models proposed by other researchers. It is concluded that these models have the limit of application to the test results. A new model is then proposed. The relationships between the test results and the calculated results are satisfactory. In this paper the effects of the strain rates and the ratio of area of the core bounded by the perimeter tie to the gross area on confinements, are also discussed through the comparison with other researchers' test data.