Impact Behavior of SBR-latex Modified Fiber Reinforced Concrete Beams

The present approach is aimed to study the impact and post-impact residual strength of SBR (Styrene Butadiene Rubber) latex modified steel fiber reinforced high strength concrete beam under repeated low-energy horizontal impact loading through experimental programs. After imparting various impact energy levels it is aimed to asses the residual strength of beams. Residual strength is the remaining life depends on parameters governing the structural response. The residual strength of structural member after receiving the impact loading is of main concern, because the remaining service period of structure mainly depends on its residual strength to withstand the loads coming on it. To obtain load-time variation under low-energy repeated impact loading frequencies, stiffness degradation and energy-time history are studied. Subsequently experimental studies are extended to obtain load-deflection variation of test specimen under four point static loading. Both impact and static loads are related by a new parameter called Dynamic Response Index (DRI). Eight different concrete beams of mix M60, M60+ Steel Fiber, M60+SBR, M60+SBR+Steel Fiber with dimensions of 150x230x3300mm were tested under two different drop heights/energy levels. The experimental results indicate that, DRI which is the indirect measure of stiffness and strength of the test specimens reduces with increase in the impact loading. The mathematical model hence could be used for predicting the stiffness degradation of beam under repeated impact loads and extrapolate the residual life of the beam. Further, the peak impact load and frequencies decrease as number of impact blows increase.