Behavior of RC Beams Subjected to High Rates of Concentrated Loading

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

“…Based on the above observations, it seems that, when subjected to high rates of concentrated loading at its mid-span, only a portion of length L eff -extending between the two discontinuity points -of the RC beam practically reacts to the imposed load, while the rest suffers insignificant, if any, cracking. As the rate of applied loading increases, L eff decreases, and hence the discontinuity points gradually come closer to the mid-span [7,8].…”

“…It is usually achieved, either experimentally [1][2][3][4][5], through the use of sophisticated testing equipment, or numerically, by employing specialised nonlinear finite-element dynamic analysis (NLFEDA) software [2][3][4][5][6][7][8]. Experimental investigations are expensive and not always capable of yielding measurements sufficiently accurate to provide a realistic description of the structural response as the duration of testing is extremely short (usually of the order of a few milliseconds (ms)), the loads generated are considerably greater by comparison with those imposed in the case of static testing and often result in explosive types of failure.…”

“…Moreover, the increase in load-carrying capacity has been found to relate with the length of the portion of the beam along which the stress waves travel up to the moment when the beam attains its load-carrying capacity [7,8]. Hence, the increase in load-carrying capacity that characterises an RC beam when the loading rate exceeds a certain threshold cannot be attributed to strain and/or stress rate effects.…”

Mathematical micromodeling of infilled frames: State of the art

“…In case studies concerned with the behavior of concrete cylindrical specimens under high loading rates, the adoption of dense FE meshes results in FE's with dimensions as small as 2-3 mm [180,118,52]. However, it should be pointed out thatespecially when modeling the behavior of brittle materials -dense FE meshes do not provide the most accurate results.…”

Editorial

“…Illuminating 'shear demand' and 'bending moment demand' plots are provided in the paper, which graphically illustrate the fact that it takes a finite time for the effects of an applied force to spread outwards from the point of impact to the supports. The authors appear to attribute this latter finding to Cotsovos et al (2008), although researchers investigating the performance of steel beams were certainly aware of this phenomenon as early as the 1950s (Parkes, 1955;Symonds, 1967). Perhaps this is another example of subject-specific 'silos' delaying wider dissemination?…”