analysis of rc beam-columns subjected to monotonic and cyclic oblique shear and axial loading

A novel algorithm is proposed to analyze the reinforced concrete (rc) beam-columns (b-cs), having rectangular or non-rectangular sections, subjected to monotonic or cyclic oblique shear and axial loading. b-cs are discretized into the macro-elements (mes) in the form of discrete finite-element (member) models, and their critical sections are discretized into fiber elements. a novel numerical convergence search method is proposed as the root-finding technique to reach the equilibrium state in each section. a three-loop iteration process is adapted employing three main characteristic strain variables, equilibrium functions, and reasonably acceptable tolerances. based on the proposed algorithm, a computer program has been developed to simulate the non-linear behavior of b-cs. a good agreement has been observed between the results obtained by applying the proposed algorithm and the experimental test results carried out by other researchers. the difference between the results of the ultimate strengths obtained using the proposed algorithm and the experimental tests on the b-cs subjected to the oblique shear force and axial load is less than 5%. the results indicate that the ultimate strain of concrete at the most compressed corner of the critical section of b-c ranges from 0.0024 to 0.0038 under maximum to zero axial loads, respectively, and the application of 0.003 value given by aci code for the ultimate strain of concrete can lead to unconventional non-conservative approximate results when b-c is subjected to an axial force larger than 70% of its axial load capacity.