Stability of Slender Reinforced Concrete Columns Subjected to Biaxially Eccentric Loads

Abstract

The elastic-plastic behavior of pin-ended reinforced concrete slender columns subjected to biaxially eccentric loads is investigated experimentally and theoretically. The ultimate loads, longitudinal and transverse deformations and the behavior up to failure of the columns are examined in detail. A total of 36 column specimens with rectangular cross sections including square sections were tested. The ratios of column length to minimum depth ranged from 6 to 26. Loads were applied monotonically at each column end with equal eccentricities at various angles from an axis of symmetry. The ultimate load carrying capacity of a slender column is reduced by additional eccentricity due to lateral deflection even in a column having a length to depth ratio of 15. The numerical analysis to solve the load-deformation response of the column predicts the test behavior very well. In the case of square columns, there is not much difference in the ultimate loads of the columns in spite of variation of the angle of eccentricity of the applied load. However, the remarkable effects of biaxial bending on the elastic-plastic behavior occurs with the rectangular columns. When the rectangular columns are subjected to biaxially eccentric load to cause bending about the near-strong axis, the ultimate loads and the deformation behavior are significantly affected by the bending about the weak axis of the section.