Behavior of R/C columns under nonproportional variations in axial and lateral loads

The study on the behavior of reinforced concrete columns subjected to the motion of earthquake suggests that the structure may experience nonproportional variations in axial and lateral forces. In order to assess the capacity of a reinforced concrete structure under nonproportional loadings, an analytical model is developed using the fiber modeling technique. The method is based on detailed analytical description of the geometry and material properties used in evaluating the behavior of the critical regions rather than a simplified and predefined set of hysteresis rules. The present study has two principal components of investigation. First, the analyses are done at the section level, to determine the influence of nonproportional axial and lateral loadings on the moment-curvature relationship for various loading level, P-M interaction diagram, degree of confinement of concrete, amount of reinforcing steel etc. Second, analyses on the response of R/C columns in terms of load-displacement hysteresis loops and curvature distribution along the height of the column subjected to nonproportinal variation in axial and lateral loads. Furthermore, the effect of degree of concrete confinement on the response of the R/C columns are also investigated. Finally, the model results are compared with experimental and other analytical models