NON-LINEAR BEHAVIOUR OF REINFORCED CONCRETE FRAMES.

This paper describes a computationally stable and efficient method of analyzing the behavior of a concrete framed structure at all stages of loading, including the load-ascending, overload stage and the post-ultimate, softening stage. Non-linear, inelastic material behavior is taken into account, as well as geometric non-linearities. The method is stable, even in the unloading range of behavior, because it simulates a deformation-controlled test, whereby the structure is subjected to controlled, progressively increasing deformation, rather than to increasing load. Any unwanted features can be stripped from the method to allow double prime rigorous double prime analysis to be carried out in accordance with the new SAA Concrete Structures Standard. Comparisons of simulated structural behavior up to collapse with actual laboratory test results have been used to check the accuracy of the method. The approach has been used to study the collapse behavior of a three-storey, two-bay multi-storey building frame.