Abstract
The load-deformation responses of the slender reinforced concrete columns under biaxially eccentric loads are solved by the numerical method of a second-order analysis, taking into account the effects of deflections and changes in stiffness of the columns on moments and forces. The column length is divided into several segments of the same length. For the equilibrium differential equation, the application of the numerical integration process of the Runge-Kutta-Gill method and the Newton-Raphson iteration technique yields the deflections corresponding to the given load, step by step. The test results given in the previously reported paper, Part 1, are compared with the numerical solutions of the analysis. The following conclusions can be drawn for the ultimate load and the deformation behavior of the slender reinforced concrete columns with square cross section. (1) The ultimate load carrying capacity of a slender column is reduced by the additional eccentricity due to lateral deflections, even in a column having a length to depth ratio of 15. (2) The numerical analysis to solve the load-deformation response of the column predicts very well the test behavior. (3) In the case of square long columns with evenly distributed reinforcement, it is remarkable that there is not much difference on ultimate loads of the columns in spite of variation of the angles of loading point. (4) The direction of deflection of the column under biaxially eccentric loads corresponds closely to the plane including the loading points and the centroids of the end section, before reaching the maximum load. However, after the attainment of the maximum load, the column has a tendency to deflect away from that plane.
