Effectiveness Factor for Shear in Concrete Beams

Abstract

A study to determine the parameters affecting web crushing failures in thin‐webbed concrete beams is summarized. Such failures are characterized by the crushing of the concrete. The average compressive stress in the web at crushing is usually lower than the concrete cylinder strength, and is defined as a function of that strength, using an effectiveness factor that has not so far been satisfactorily quantified. By means of an extensive statistical study of published test data, the primary variables affecting effectiveness factor are isolated and used to develop a model, which is proposed for evaluation of the effectiveness factor. The most significant variables are shown to be the web width/depth ratio and the shear span/depth ratio. This finding confirms some empirical results from past studies, but does not support the common practice of defining web effectiveness factor in terms of concrete cylinder strength as the only variable.