Impact Response of RC Beams Through Contacting and Non-contacting Sensors

This paper presents the performance of reinforced concrete beams which were tested under an instrumented drop-weight impact testing facility. The reinforced concrete beams of size 2.5 × 0.25 × 0.15 m were made with M40 grade concrete. The beams were having two different quantities of reinforcement, i.e., 2.74 and 4.12%. A rigid steel mass of 200 kg was dropped on the beams from 1 to 1.5 m heights. The deflection, strain in steel reinforcement, reaction force, etc., were measured using various contacting and non-contacting sensors during the impact event. For the measurement of deflection, the linear variable differential transformers (LVDTs) and laser displacement sensors (LDS) were used as contacting and non-contacting sensors, respectively. The response obtained using these two sensors was also compared and discussed. From the experimental investigation, it was observed that the behaviour of these two sensors was completely different under impact loading though both were linear positioning sensors. It was observed that the accurate measurement of deflection was impossible in the case of LVDTs and the results were also less promising compared to LDS. The deflection measured by LVDT was about 5–7 times the deflection measured by LDS. Thus, the non-contacting sensor was noticed to have performed better under impact loading compared to contacting sensor LVDT. The peak impact force increased by 45.5% with the increase in the drop height. The cracks in the RC beams initiated from their soffit under impact loading; however, the failure mode was noticed differently. Beam A1 witnessed flexural deformation while beam A3 had shown splitting damage.