A simplified approach for assessing the load-carrying capacity of reinforced concrete beams under concentrated load applied at high rates

The present article proposes a simplified method for evaluating the load-carrying capacity of reinforced concrete beams when subjected to concentrated impact loading at their mid-span. The method links the enhancement of load-carrying capacity with the shortening of the portion (termed herein effective length) of the beam which has been found both experimentally and numerically to resist the action of the applied load under increasing loading rates. The proposed method is validated through a comparative study of its predictions with published experimental data, as well as numerical results obtained by means of three dimensional dynamic nonlinear finite-element analyses. The proposed method is not intended to explain the rate effect; it merely uses the apparent link between “the effective length” and the imposed rate of loading as the means for the development of a simplified approach suitable for use in practical structural design.