A study of dowel action in reinforced concrete beams

Abstract

This paper reopens the question concerning the contribution of dowel action to the shear capacity of reinforced concrete beams. First, a literature survey on the subject reveals that, despite the implicit belief in much of the current design thinking that dowel action can play a significant role in the mechanism through which shear is carried in a beam, opinion on the matter is divided and often contradictory. Secondly, a programme of beam tests in which the total amount of main steel remains constant but the number of bars (and hence their diameter) is varied is reported, the results showing that the bar diameter has no effect on the load-carrying capacity of the members, suggesting, therefore, that dowel action is unlikely to be a significant factor in the internal load-transfer mechanism leading to final collapse. Faunally, these experimental findings are confirmed by an established finite-element package which faithfully reproduced the experimental results, on the basis that the numerical model makes no allowances for the so-called dowel-action effect.