Short reinforced concrete column capacity under biaxial bending and axial load

The paper describes the development of a simple theoretical approach in estimating the capacity of short reinforced concrete (RC) columns under biaxial bending and axial load. The developed approach considers the nonlinear stress-strain relations of concrete and reinforcing steel and does not make the assumption about the limiting strain of extreme compression fiber of concrete. The solution is obtained using a nonlinearly constrained optimization algorithm. The approach was used to estimate the theoretical capacities of many tested RC columns found in the literature. A probabilistic analysis of the modeling errors was carried out using the ratios of the test-to-predicted results. The probabilistic analysis was extended to include two simplified theoretical methods: the reciprocal load method given by Bresler and the failure surface method given by Hsu.Key words: biaxial bending, modeling error, optimization, probability distribution.