Beam theory – a proposed alternative basis for RC design

It has recently been shown that the ever-increasing complexity and inability of methods used for the design of reinforced concrete (RC) structures to consistently safeguard against brittle types of failure is the outcome of the conflict between the assumptions of the underlying theory and the fundamental concrete material characteristics. This paper demonstrates that these drawbacks can be eliminated through a coherent alternative theory developed on the basis of simplified beam theory modified to account for true concrete behaviour. Through the use of experimental information obtained from the literature, the proposed theory shows that, in contrast with widely held views, a structural member's load-carrying capacity depends solely on the strength of the compressive zone, which was found to be significantly larger than what it is widely considered to be. Moreover, load transfer is accomplished by the bending action of the concrete cantilevers formed between consecutive inclined or flexural cracks in the tensile zone. The above findings essentially underline the development of an alternative design method – the compressive force path method – and this is an indication of the suitability of the proposed theory to open up new possibilities for improving RC design.