Influence of high loading rates on behavior of reinforced concrete beams with different aspect ratios – A numerical study

• Influence of loading rate on RC beams is numerically investigated.
• Loading rate has significant influence on load-carrying capacity and failure mode.
• For beams with high aspect ratios, failure changes from flexure to shear.
• The location of first crack gets closer to loading point with high loading rate.
• Failure mode of beams with short aspect ratio is almost unaffected by loading rate.

The failure mode of the reinforced concrete (RC) beams having varying aspect ratios (ratio of shear span to depth) is known to vary from predominantly shear to predominantly flexure with the increase in aspect ratio. It is further known that there is a significant influence of loading rate on the resistance and the failure mode of the beams, namely the failure mode of a beam failing by flexure under static loads changes to shear failure when subjected to high loading rate. In this work, numerical investigations are carried out on cantilever RC beams having different aspect ratios under high loading rates. First, the failure modes of the beams are obtained under static loading and the same is compared with the well-accepted results in literature. The numerical modeling technique already proven by the authors on various problems is then utilized to predict the failure modes of the beams when they are subjected to higher loading rates. It has been shown that the influence of loading rate is much more prominent on beams with larger aspect ratios compared to the beams with smaller aspect ratios. The failure mode of beams with large aspect ratios tends to change from flexure to shear with increasing loading rate. For beams with small aspect ratios, the failure mode is relatively unaffected by the loading rate. The increase in resistance due to loading rate for beams with different aspect ratios is also evaluated and reported.