Reappraisal of methods for calculating flexural capacity of reinforced concrete members

A comparison of the predicted and experimentally-established behaviour of over 150 reinforced concrete beam specimens (selected from 465 test results considered) revealed that around 20% of the specimens exhibited shear failure rather than the expected flexural failure. The work presented in this paper investigated the possibility that the causes of shear failure reflected shortcomings of the code methods adopted for calculating flexural capacity. It was found that the predicted values of flexural capacity tended to underestimate their experimentally-established counterparts by up to 17% on average. It was shown that by accounting for the triaxial stress conditions invariably developing in the compressive zone through a simple modification of code-proposed stress blocks, the correlation between predicted and experimental values was similar to the best possible one resulting from the development and use of an artificial neural network model.