The energy method previously developed to analyze the incremental collapse of steel structures is extended in this investigation to the incremental collapse analysis of reinforced concrete framed structures. To use this method of analysis, first, the flexural rigidity and the plastic bending moment capacity for reinforced concrete beam cross-sections as well as for reinforced concrete column cross-sections subjected to varying axial loads, are defined. The maximum available plastic hinge rotation capacity of each cross-section is also computed.; As examples of the use of the methods developed herein, the collapse load of various reinforced concrete framed structures is computed together with the corresponding complete incremental collapse envelope. It is demonstrated that this envelope has three distinct regions: an inner region in which all of the load ranges will lead to an elastic response of the structure, a middle region in which all load ranges will lead to shake down of the structure, and an outer region in which all load ranges will lead to the incremental collapse of the structure.; It is shown that the presence of even a small constant vertical load on the structure will alter the shape of the incremental collapse envelope. This distortion of the envelope becomes larger as the magnitude of the vertical constant load becomes larger.; A computer program has been developed herein to use the energy method together with the finite element method of analysis. It may be used to compute the plastic collapse load as well as various points on the incremental collapse envelope of reinforced concrete framed structures.
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