Failure and strength of high-strength concrete columns subjected to eccentric loads

xThe objective of this paper is to verify the basic design rules of high-st rength concrete columns. A total of 32 column specimens were tested to inve stigate structural behavior and strength of eccentrically, loaded reinforce d concrete tied columns. Main variables included in this test program were concrete compressive strength, steel amount, eccentricity: and slenderness ratio The concrete compressive strength varied from 34.9 to 93.2 MPa, and t he longitudinal steel ratios were between 1.13 and 5.51%. Test results of c olumn sectional strength are compared with the results of analyses by ACI r ectangular stress block, trapezoidal stress block, and modified rectangular stress block. Axial force-moment-curvature analysis is also performed for predicting axial load-moment strength and compared with thp test results. T he ACI rectangular stress block provides overestimated column strengths for the lightly reinforced high-strength column specimens. The calculated stre ngths by moment-curvature analyses are highly affected by k(3) values of th e concrete stress-strain curve. Observed failure mode, concrete ultimate st rain, and stress block parameters are discussed.